2024-03-29T00:21:12Zhttps://vtechworks.lib.vt.edu/server/oai/requestoai:vtechworks.lib.vt.edu:10919/1172222024-03-12T15:59:32Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
A data-driven approach to understand factors contributing to exoskeleton use-intention in construction
Kim, Sunwook
Moore, Albert
Ojelade, Aanuoluwapo
Gutierrez, Nancy
Harris-Adamson, Carisa
Barr, Alan
Srinivasan, Divya
Nussbaum, Maury A.
Exoskeletons
Construction
Work-related musculoskeletal disorders (WMSDs) remain an important heath concern for construction workers. Occupational exoskeletons (EXOs) are a new ergonomic intervention to control WMSD risk, yet their adoption has been low in construction. We explored contributing factors to EXO use-intention, by building a decision tree to predict the intention to try an exoskeleton using responses to an online survey. Variable selection and hyperparameter tuning were used respectively to reduce the number of potential predictors, and for a better prediction performance. Performance was assessed using four common metrics. The importance of variables in the final tree was calculated to understand which variable had a greater influence. The final tree had moderate prediction performance. Important variables identified were associated with opinions on EXO use, demographics, job demands, and perceived potential risks. The key influential variables were EXOs becoming standard equipment and fatigue reduction with EXO use. Practical implications of the findings are discussed.
2023-12-19T14:20:47Z
2023-12-19T14:20:47Z
2023-10-25
Article - Refereed
2169-5067
https://hdl.handle.net/10919/117222
https://doi.org/10.1177/21695067231192932
Kim, Sun Wook [0000-0003-3624-1781]
Nussbaum, Maury [0000-0002-1887-8431]
Ojelade, Aanuoluwapo [0000-0001-9715-3254]
1071-1813
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
SAGE
oai:vtechworks.lib.vt.edu:10919/1160782023-08-23T07:12:48Zcom_10919_24216com_10919_5539com_10919_24217col_10919_24286col_10919_24292
Transient use of hemolymph for hydraulic wing expansion in cicadas
Salcedo, Mary K.
Ellis, Tyler E.
Saenz, Angela S.
Lu, Joyce
Worrell, Terrell
Madigan, Michael L.
Socha, John J.
imaginal ecdysis
schistocerca-gregaria
periodical cicadas
circulatory organs
desert locust
physiology
eclosion
Insect wings must be flexible, light, and strong to allow dynamic behaviors such as flying, mating, and feeding. When winged insects eclose into adults, their wings unfold, actuated hydraulically by hemolymph. Flowing hemolymph in the wing is necessary for functioning and healthy wings, both as the wing forms and as an adult. Because this process recruits the circulatory system, we asked, how much hemolymph is pumped into wings, and what happens to the hemolymph afterwards? Using Brood X cicadas (Magicicada septendecim), we collected 200 cicada nymphs, observing wing transformation over 2 h. Using dissection, weighing, and imaging of wings at set time intervals, we found that within 40 min after emergence, wing pads morphed into adult wings and total wing mass increased to similar to 16% of body mass. Thus, a significant amount of hemolymph is diverted from body to wings to effectuate expansion. After full expansion, in the similar to 80 min after, the mass of the wings decreased precipitously. In fact, the final adult wing is lighter than the initial folded wing pad, a surprising result. These results demonstrate that cicadas not only pump hemolymph into the wings, they then pump it out, producing a strong yet lightweight wing.
2023-08-22T13:59:00Z
2023-08-22T13:59:00Z
2023-04
Article - Refereed
2045-2322
6298
http://hdl.handle.net/10919/116078
https://doi.org/10.1038/s41598-023-32533-4
13
1
37072416
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Nature Portfolio
oai:vtechworks.lib.vt.edu:10919/1033952021-05-21T07:11:35Zcom_10919_78629com_10919_78628com_10919_24217com_10919_5539col_10919_78630col_10919_24292
A robust pooled testing approach to expand COVID-19 screening capacity
Bish, Douglas R.
Bish, Ebru K.
El-Hajj, Hussein
Aprahamian, Hrayer
Industrial and Systems Engineering
Limited testing capacity for COVID-19 has hampered the pandemic response. Pooling is a testing method wherein samples from specimens (e.g., swabs) from multiple subjects are combined into a pool and screened with a single test. If the pool tests positive, then new samples from the collected specimens are individually tested, while if the pool tests negative, the subjects are classified as negative for the disease. Pooling can substantially expand COVID-19 testing capacity and throughput, without requiring additional resources. We develop a mathematical model to determine the best pool size for different risk groups, based on each group's estimated COVID-19 prevalence. Our approach takes into consideration the sensitivity and specificity of the test, and a dynamic and uncertain prevalence, and provides a robust pool size for each group. For practical relevance, we also develop a companion COVID-19 pooling design tool (through a spread sheet). To demonstrate the potential value of pooling, we study COVID-19 screening using testing data from Iceland for the period, February-28-2020 to June-14-2020, for subjects stratified into high- and low-risk groups. We implement the robust pooling strategy within a sequential framework, which updates pool sizes each week, for each risk group, based on prior week's testing data. Robust pooling reduces the number of tests, over individual testing, by 88.5% to 90.2%, and 54.2% to 61.9%, respectively, for the low-risk and high-risk groups (based on test sensitivity values in the range [0.71, 0.98] as reported in the literature). This results in much shorter times, on average, to get the test results compared to individual testing (due to the higher testing throughput), and also allows for expanded screening to cover more individuals. Thus, robust pooling can potentially be a valuable strategy for COVID-19 screening.
2021-05-20T12:08:16Z
2021-05-20T12:08:16Z
2021-02-08
Article - Refereed
1932-6203
e0246285
http://hdl.handle.net/10919/103395
https://doi.org/10.1371/journal.pone.0246285
16
2
33556129
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1163892023-10-03T15:06:58Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Novel In-Vehicle Gesture Interactions: Design and Evaluation of Auditory Displays and Menu Generation Interfaces
Tabbarah, Moustafa
Cao, Yusheng
Abu Shamat, Ahmad
Fang, Ziming
Li, Lingyu
Jeon, Myounghoon
Using in-vehicle infotainment systems degrades driving performance and increases crash risk. To address this, we developed air gesture interfaces using various auditory displays. Thirty-two participants drove a simulator with air-gesture menu navigation tasks. A 4x2 mixed-model design was used to explore the effects of auditory displays as a within-subjects variable (earcons, auditory icons, spearcons, and no-sound) and menu-generation interfaces as a between-subjects variable (fixed and adaptive) on driving performance, secondary task performance, eye glance, and user experience. The adaptive condition centered the menu around the user’s hand position at the moment of activation, whereas the fixed condition located the menu always at the same position. Results demonstrated that spearcons provided the least visual distraction, least workload, best system usability and was favored by participants; and that fixed menu generation outperformed adaptive menu generation in driving safety and secondary task performance. Findings will inform design guidelines for in-vehicle air-gesture interaction systems.
2023-10-02T14:51:09Z
2023-10-02T14:51:09Z
2023-09-18
2023-10-01T07:51:20Z
Article - Refereed
http://hdl.handle.net/10919/116389
https://doi.org/10.1145/3580585.3607164
en
http://creativecommons.org/licenses/by-nc/4.0/
The author(s)
Creative Commons Attribution-NonCommercial 4.0 International
ACM
oai:vtechworks.lib.vt.edu:10919/819542023-07-12T17:57:36Zcom_10919_24217com_10919_5539com_10919_79468com_10919_78628col_10919_24292col_10919_79480
Effects of Government Spending on Research Workforce Development: Evidence from Biomedical Postdoctoral Researchers
Hur, Hyungjo
Ghaffarzadegan, Navid
Hawley, Joshua D.
Industrial and Systems Engineering
We examine effects of government spending on postdoctoral researchers’ (postdocs) productivity in biomedical sciences, the largest population of postdocs in the US. We analyze changes in the productivity of postdocs before and after the US government’s 1997 decision to increase NIH funding. In the first round of analysis, we find that more government spending has resulted in longer postdoc careers. We see no significant changes in researchers’ productivity in terms of publication and conference presentations. However, when the population is segmented by citizenship, we find that the effects are heterogeneous; US citizens stay longer in postdoc positions with no change in publications and, in contrast, international permanent residents (green card holders) produce more conference papers and publications without significant changes in postdoc duration. Possible explanations and policy implications of the analysis are discussed.
2018-01-29T15:30:07Z
2018-01-29T15:30:07Z
2015-05-01
Article - Refereed
http://hdl.handle.net/10919/81954
https://doi.org/10.1371/journal.pone.0124928
10
5
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
PLOS
oai:vtechworks.lib.vt.edu:10919/943492020-10-08T18:34:40Zcom_10919_24217com_10919_5539col_10919_24292
Dell's SupportAssist customer adoption model: enhancing the next generation of data-intensive support services
Ghaffarzadegan, Navid
Rad, Armin A.
Xu, Ran
Middlebrooks, Sam E.
Mostafavi, Sarah
Shepherd, Michael
Chambers, Landon
Boyum, Todd
Industrial and Systems Engineering
We developed a decision support system to model, analyze, and improve market adoption of Dell's SupportAssist program. SupportAssist is a proactive and preventive support service capability that can monitor system operations data from all connected Dell devices around the world and predict impending failures in those devices. Performance of such data-intensive services is highly interconnected with market adoption: service performance depends on the richness of the customer database, which is influenced by customer adoption that in turn depends on customer satisfaction and service performancea reinforcing feedback loop. We developed the SupportAssist adoption model (SAAM). SAAM utilizes various data sources and modeling techniques, particularly system dynamics, to analyze market response under different strategies. Dell anticipates improving market adoption of SupportAssist and revenue from support services, as results of using this analytical tool. Copyright (c) 2018 The Authors System Dynamics Review published by John Wiley & Sons Ltd on behalf of System Dynamics Society
2019-10-04T14:40:50Z
2019-10-04T14:40:50Z
2017-12
Article - Refereed
0883-7066
http://hdl.handle.net/10919/94349
https://doi.org/10.1002/sdr.1587
33
3-4
1099-1727
en
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
oai:vtechworks.lib.vt.edu:10919/1179212024-03-14T14:31:38Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_23274col_10919_70873col_10919_24292col_10919_23275
Improving Assessment in Kidney Transplantation by Multitask General Path Model
Lan, Qing
Chen, Xiaoyu
Li, Murong
Robertson, John
Lei, Yong
Jin, Ran
Kidney transplantation helps end-stage patients regain health and quality-of-life. The decisions for matching donor kidneys and recipients affect success of transplantation. However, current kidney matching decision procedures do not consider viability loss during preservation. The objective here is to forecast heterogeneous kidney viability, based on historical datasets to support kidney matching decision-making. Six recently procured porcine kidneys were used to conduct viability assessment experiments to validate the proposed multitask general path model. The model forecasts kidney viability by transferring knowledge from learning the commonality of all kidneys and the heterogeneity of each kidney. The proposed model provides exactly accurate kidney viability forecasting results compared to the state-of-the-art models including a multitask learning model, a general path model, and a general linear model. The proposed model provides satisfactory kidney viability forecasting accuracy because it quantifies the degradation information from trajectory of a viability loss path. It transfers knowledge of common effects from all kidneys and identifies individual effects of each kidney. This method can be readily extended to other decision-making scenarios in kidney transplantation to improve overall assessment performance. For example, analytical generalizations gained by modeling have been validated based on needle biopsy data targeting the improvement of tissue extraction accuracy. The proposed model applied in multiple kidney assessment processes in transplantation can potentially reduce the kidney discard rate by providing effective kidney matching decisions. Thus, the increased kidney utilization rate will benefit more patients and prolong their lives.
2024-02-12T14:31:46Z
2024-02-12T14:31:46Z
2023
Article - Refereed
https://hdl.handle.net/10919/117921
Jin, Ran [0000-0003-3847-4538]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1136772023-02-07T08:13:37Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Failure-Averse Active Learning for Physics-Constrained Systems
Lee, Cheolhei
Wang, Xing
Wu, Jianguo
Yue, Xiaowei
Active learning is a subfield of machine learning that is devised for the design and modeling of systems with highly expensive sampling costs. Industrial and engineering systems are generally subject to physics constraints that may induce fatal failures when they are violated, while such constraints are frequently underestimated in active learning. In this paper, we develop a novel active learning method that avoids failures considering implicit physics constraints that govern the system. The proposed approach is driven by two tasks: safe variance reduction explores the safe region to reduce the variance of the target model, and safe region expansion aims to extend the explorable region. The integrated acquisition function is devised to conflate two tasks and judiciously optimize them. The proposed method is applied to the composite fuselage assembly process with consideration of material failure using the Tsai-Wu criterion, and it is able to achieve zero failure without the knowledge of explicit failure regions. <italic>Note to Practitioners</italic>—This paper is motivated by engineering systems with implicit physics constraints related to system failures. Implicit physics constraints refer to failure processes in which explicit analytic forms do not exist, so demanding numerical simulations or real experiments are required to check one’s safety. The main objective of this paper is to develop an active learning strategy that safely learns the target process in the system by minimizing failures without preliminary reliability analysis. The proposed method mainly targets real systems whose failure conditions are not thoroughly investigated or uncertain. We applied the proposed method to the predictive modeling of composite fuselage deformation in the aircraft manufacturing process, and it achieved zero failure in sampling by considering the composite failure criterion.
2023-02-06T13:46:32Z
2023-02-06T13:46:32Z
2022-10
2023-02-05T03:36:47Z
Article - Refereed
1545-5955
http://hdl.handle.net/10919/113677
https://doi.org/10.1109/TASE.2022.3213827
99
Yue, Xiaowei [0000-0001-6019-0940]
1558-3783
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
IEEE
oai:vtechworks.lib.vt.edu:10919/1178372024-02-05T13:10:44Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
What Do You Want for In-Vehicle Agents? One Fits All vs. Multiple Specialized Agents
Park, Se Hyeon
Lee, Seul Chan
Wang, Manhua
Hock, Philipp
Baumann, Martin
Jeon, Myounghoon
Intelligent agents
In-vehicle driving agents
It is expected that in-vehicle intelligent agents (IVIAs) become an important user interface in automated driving, and much research on how to design IVIAs considering user needs and scenarios has been conducted. The question arising here is whether people want to have one almighty agent connecting to all user's data sources and dealing with all situations, including driving contexts. Another plausible form is multiple specialized agents that play the role only in each task context. As a first step in answering the question, we developed two plausible scenarios of interacting with IVIAs and presented the video. In both scenarios, a user of IVIAs experiences embarrassing situations because of the connectivity of IVIAs. We expect that this effort can be a starting point to understand users' needs and requirements to develop and design IVIAs in terms of connectivity.
2024-02-02T18:28:31Z
2024-02-02T18:28:31Z
2022-09-17
Conference proceeding
9781450394284
https://hdl.handle.net/10919/117837
https://doi.org/10.1145/3544999.3550153
Jeon, Myounghoon [0000-0003-2908-671X]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/1073332022-01-04T15:08:01Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Flipping the Way We Teach Writing: A Perspective on Student Perceptions of a Hybrid Undergraduate Technical Writing Course in Agriculture
Carper, Kathleen
Anderson, James
As directives from university and college administrators to shift to alternative forms of instructional delivery to traditional lecture increase, especially in light of current concerns with COVID-19, the readiness of faculty to offer quality instruction may be put into question. This study looked at student perceptions about hybrid learning for students enrolled in a technical writing course to glean insights on how this alternative instructional approach impacts student engagement and thus the ability to accomplish the learning objectives for a technical writing course that was revised from a standard flipped class to a hybrid class. Guided by a systems thinking framework, students enrolled in this technical writing course completed an anonymous, qualitative survey with open-ended, free response questions regarding their perceptions about the connections between the online and in-person components of the course and how various factors within the class, as a system, impacted their learning experience. Four themes were identified: students appreciate autonomy, students appreciate structure, students need access to the instructor, and students value meaningful interactions. Discussion includes considerations for instructors looking to incorporate alternative instructional strategies, like a hybrid learning modality, in their agriculture courses.
2022-01-03T23:13:30Z
2022-01-03T23:13:30Z
2021-10
2022-01-03T23:13:28Z
Article - Refereed
http://hdl.handle.net/10919/107333
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1116942022-09-03T07:12:50Zcom_10919_24217com_10919_5539col_10919_24292
Automatic Recognition and Analysis of Balance Activity in Community-Dwelling Older Adults: Algorithm Validation
Hsu, Yu-Cheng
Wang, Hailiang
Zhao, Yang
Chen, Frank
Tsui, Kwok-Leung
fall risk
balance
activity recognition
automatic framework
community-dwelling elderly
Background: Clinical mobility and balance assessments identify older adults who have a high risk of falls in clinics. In the past two decades, sensors have been a popular supplement to mobility and balance assessment to provide quantitative information and a cost-effective solution in the community environment. Nonetheless, the current sensor-based balance assessment relies on manual observation or motion-specific features to identify motions of research interest. Objective: The objective of this study was to develop an automatic motion data analytics framework using signal data collected from an inertial sensor for balance activity analysis in community-dwelling older adults. Methods: In total, 59 community-dwelling older adults (19 males and 40 females; mean age = 81.86 years, SD 6.95 years) were recruited in this study. Data were collected using a body-worn inertial measurement unit (including an accelerometer and a gyroscope) at the L4 vertebra of each individual. After data preprocessing and motion detection via a convolutional long short-term memory (LSTM) neural network, a one-class support vector machine (SVM), linear discriminant analysis (LDA), and k-nearest neighborhood (k-NN) were adopted to classify high-risk individuals. Results: The framework developed in this study yielded mean accuracies of 87%, 86%, and 89% in detecting sit-to-stand, turning 360 degrees, and stand-to-sit motions, respectively. The balance assessment classification showed accuracies of 90%, 92%, and 86% in classifying abnormal sit-to-stand, turning 360 degrees, and stand-to-sit motions, respectively, using Tinetti Performance Oriented Mobility Assessment-Balance (POMA-B) criteria by the one-class SVM and k-NN. Conclusions: The sensor-based approach presented in this study provided a time-effective manner with less human efforts to identify and preprocess the inertial signal and thus enabled an efficient balance assessment tool for medical professionals. In the long run, the approach may offer a flexible solution to relieve the community's burden of continuous health monitoring.
2022-09-02T13:58:10Z
2022-09-02T13:58:10Z
2021-12-20
Article - Refereed
e30135
http://hdl.handle.net/10919/111694
https://doi.org/10.2196/30135
23
12
34932008
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
JMIR Publications
oai:vtechworks.lib.vt.edu:10919/1126342022-11-16T08:12:55Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Task demand and load carriage experience affect gait variability among military cadets
Ulman, Sophia
Srinivasan, Divya
Nussbaum, Maury A.
Clinical Research
Rehabilitation
Load carriage is an inevitable daily task for soldiers. The purposes of this study were to explore the extent to which gait variability (GV) is affected by load carriage and experience among military cadets, and whether experience-related differences in GV are dependent on task demand. Two groups of cadets (30 experienced, 30 less experienced) completed a load carriage task in each of three load conditions (no load, 16 kg, 32 kg). Three categories of GV measures were obtained: spatiotemporal variability, joint kinematic variability, and Lyapunov exponents. Compared to traditional mean gait measures, GV measures were more discriminative of experience: although both groups showed similar mean gait measures, the experienced participants had reduced variability in spatiotemporal measures (p ≤ 0.008) and joint kinematics (p ≤ 0.004), as well as lower levels of long-term local dynamic stability at the ankle (p = 0.040). In both groups, heavier loads were also caused increased GV (p ≤ 0.018) and enhanced short-term local dynamic stability at the knee (p = 0.014). These results emphasize the importance of GV measures, which may provide a more complete description of adaptability, stability, and control; highlight alternate movement strategies during more difficult load carriage; and capture experience-related differences in load carriage strategies.
2022-11-15T13:57:54Z
2022-11-15T13:57:54Z
2022-11
2022-11-15T13:53:35Z
Article - Refereed
2045-2322
PMC9626617
10.1038/s41598-022-22881-y (PII)
http://hdl.handle.net/10919/112634
https://doi.org/10.1038/s41598-022-22881-y
12
1
Nussbaum, Maury [0000-0002-1887-8431]
36319838
2045-2322
en
https://www.ncbi.nlm.nih.gov/pubmed/36319838
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Springer Nature
oai:vtechworks.lib.vt.edu:10919/1175982024-03-14T15:31:45Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Technological and Social Distractions at Unsignalized and Signalized Campus Crosswalks: A Multi-Stage Naturalistic Observation Study
Dam, Abhraneil
Oberoi, Pooja
Pierson, Jake
Jeon, Myounghoon
Patrick, Rafael
Campus crosswalk
Naturalistic observations
Personal listening device
Vulnerable road users
Technological distractions
Social distractions
Gestures
The student population between 18 to 25 years of age remains the largest user group
for earphones or personal listening devices (PLDs). PLDs can be quite distracting,
especially when its users are performing focused tasks such as street crossings. On
large rural university campuses, students often must cross multiple unsignalized
crosswalks to get to their destination. To evaluate the dangers of PLD use and
pedestrian behavior while navigating crosswalks, we systematically observed multiple
crosswalks of a sprawling rural university campus in south-west Virginia, USA. The
study was conducted following a three-stage protocol consisting of 9 hours of on-site
video recorded observations, a survey of 135 pedestrians, and finally, 2 focus groups
with 8 pedestrians in total. This three-stage approach provides a comprehensive
understanding of pedestrian behavior and the university-campus culture. Results from
this study show the extent of distracted behaviors, safety measures adopted by
pedestrians, and identify future research directions involving safety countermeasures
for distracted pedestrians.
2024-01-23T14:35:34Z
2024-01-23T14:35:34Z
2023-08
Article
1369-8478
https://hdl.handle.net/10919/117598
https://doi.org/10.1016/j.trf.2023.07.003
97
Patrick, Rafael [0000-0002-7503-2184]
Jeon, Myounghoon [0000-0003-2908-671X]
1873-5517
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Elsevier
oai:vtechworks.lib.vt.edu:10919/985142023-11-29T16:17:29Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_5524col_10919_70873col_10919_24292col_10919_89575
Effects of Intersection Lighting Design on Nighttime Visual Performance of Drivers
Bhagavathula, Rajaram
Gibbons, Ronald B.
Nussbaum, Maury A.
Industrial and Systems Engineering
Virginia Tech Transportation Institute
Physical Sciences
Construction & Building Technology
Optics
Intersection lighting design
intersection lighting design standards
isolated intersections
night driving
rural intersections
safety
visual performance
SMALL TARGET VISIBILITY
CONTRAST SENSITIVITY
PEDESTRIAN VISIBILITY
ILLUMINANCE
SAFETY
Building & Construction
Nighttime crashes at intersections present a major traffic safety issue in the United States. Existing approaches to intersection lighting design do not account for a driver’s visual performance or the potential interactive effects of vehicle headlamps and roadway lighting. For effective design lighting at intersections, empirical research is required to evaluate the effects of lighting configuration (part of the intersection illuminated) and lighting levels on nighttime driver visual performance. The current study had two goals: First, to quantify visual performance in three lighting configurations (illuminating the intersection box, approach, or both) and second, to determine what lighting levels within each lighting configuration support the best visual performance. The study involved a target detection task completed at night on a realistic roadway intersection. Illuminating the intersection box led to superior visual performance, as indicated by longer target detection distances, fewer missed targets, and more targets identified within a safe stopping distance. For this lighting configuration, visual performance plateaued between 7 and 10 lx of mean intersection illuminance. These results have important implications for the design of intersection lighting at isolated/rural intersections, specifically that illuminating the intersection box is an effective strategy to increase nighttime visual performance for a wider range of driver ages and could also be an energy-efficient solution.
2020-05-21T16:44:22Z
2020-05-21T16:44:22Z
2018-01-01
2020-05-21T16:44:18Z
Article - Refereed
1550-2724
http://hdl.handle.net/10919/98514
https://doi.org/10.1080/15502724.2017.1321485
14
1
Nussbaum, Maury [0000-0002-1887-8431]
Bhagavathula, Rajaram [0000-0002-1119-8169]
Gibbons, Ronald [0000-0002-4457-2444]
1550-2716
en
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000428302200004&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Taylor & Francis
oai:vtechworks.lib.vt.edu:10919/1027542021-06-21T19:04:58Zcom_10919_78629com_10919_78628com_10919_8195com_10919_25799com_10919_24217com_10919_5539com_10919_84995com_10919_5553col_10919_78791col_10919_18629col_10919_24292col_10919_84996
Therapeutic effects of peripherally administrated neural crest stem cells on pain and spinal cord changes after sciatic nerve transection
Zhang, Yang
Xu, Xiang
Tong, Yuxin
Zhou, Xijie
Du, Jian
Choi, In Y.
Yue, Shouwei
Lee, Gabsang
Johnson, Blake N.
Jia, Xiaofeng
Industrial and Systems Engineering
School of Neuroscience
Background
Severe peripheral nerve injury significantly affects patients’ quality of life and induces neuropathic pain. Neural crest stem cells (NCSCs) exhibit several attractive characteristics for cell-based therapies following peripheral nerve injury. Here, we investigate the therapeutic effect of NCSC therapy and associated changes in the spinal cord in a sciatic nerve transection (SNT) model.
Methods
Complex sciatic nerve gap injuries in rats were repaired with cell-free and cell-laden nerve scaffolds for 12 weeks (scaffold and NCSC groups, respectively). Catwalk gait analysis was used to assess the motor function recovery. The mechanical withdrawal threshold and thermal withdrawal latency were used to assess the development of neuropathic pain. Activation of glial cells was examined by immunofluorescence analyses. Spinal levels of extracellular signal-regulated kinase (ERK), NF-κB P65, brain-derived neurotrophic factor (BDNF), growth-associated protein (GAP)-43, calcitonin gene-related peptide (CGRP), and inflammation factors were calculated by western blot analysis.
Results
Catwalk gait analysis showed that animals in the NCSC group exhibited a higher stand index and Max intensity At (%) relative to those that received the cell-free scaffold (scaffold group) (p < 0.05). The mechanical and thermal allodynia in the medial-plantar surface of the ipsilateral hind paw were significantly relieved in the NCSC group. Sunitinib (SNT)-induced upregulation of glial fibrillary acidic protein (GFAP) (astrocyte) and ionized calcium-binding adaptor molecule 1 (Iba-1) (microglia) in the ipsilateral L4–5 dorsal and ventral horn relative to the contralateral side. Immunofluorescence analyses revealed decreased astrocyte and microglia activation. Activation of ERK and NF-κB signals and expression of transient receptor potential vanilloid 1 (TRPV1) expression were downregulated.
Conclusion
NCSC-laden nerve scaffolds mitigated SNT-induced neuropathic pain and improved motor function recovery after sciatic nerve repair. NCSCs also protected the spinal cord from SNT-induced glial activation and central sensitization.
2021-03-22T11:57:55Z
2021-03-22T11:57:55Z
2021-03-15
2021-03-21T04:25:04Z
Article - Refereed
Stem Cell Research & Therapy. 2021 Mar 15;12(1):180
http://hdl.handle.net/10919/102754
https://doi.org/10.1186/s13287-021-02200-4
en
http://creativecommons.org/licenses/by/4.0/
The Author(s)
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/258342023-07-12T17:57:36Zcom_10919_24217com_10919_5539col_10919_24292
Enhancing Lagrangian dual optimization for linear programs by obviating nondifferentiability
Sherali, Hanif D.
Lim, C.
Industrial and Systems Engineering
Nondifferentiable optimization
Lagrangian relaxation
Lagrangian dual
Perturbation technique
Barrier-lagrangian reformulation
Variable target value
Primal solutions
Subgradient
Minimization
Convergence
Relaxations
Algorithms
We consider non differentiable optimization problems that arise when solving Lagrangian duals of large-scale linear programs. Different from traditional subgradient-based approaches, we design two new methods that attempt to circumvent or obviate the nondifferentiability of the objective function, so that standard differentiable optimization techniques could be used. These methods, called the perturbation technique and the barrier-Lagrangian reformulation, are implemented as initialization procedures to provide a warm start to a theoretically convergent nondifferentiable optimization algorithm. Our computational study reveals that this two-phase strategy produces much better solutions with less computation in comparison with both the stand-alone nondifferentiable optimization procedure employed, and the popular Held-Wolfe-Crowder subgradient heuristic. Furthermore, the best version of this composite algorithm is shown to consume only about 3.19% of the CPU time required by the commercial linear programming solver CPLEX 8.1 (using the dual simplex option) to produce the same quality solutions. We also demonstrate that this initialization technique greatly facilitates quick convergence in the primal space when used as a warm start for ergodic-type primal recovery schemes.
2014-03-05T14:00:24Z
2014-03-05T14:00:24Z
2007
2014-02-05
Article - Refereed
Sherali, Hanif D.; Lim, Churlzu. Enhancing Lagrangian dual optimization for linear programs by obviating nondifferentiability. INFORMS Journal on Computing 2007 19:1, 3-13. doi: 10.1287/ijoc.1050.0158
1091-9856
http://hdl.handle.net/10919/25834
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.1050.0158
https://doi.org/10.1287/ijoc.1050.0158
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/1137932024-03-12T15:59:32Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Effects of Back-support Exoskeletons on Task Performance and Usability During Simulated Construction-relevant Tasks
Ojelade, Aanuoluwapo
Morris, Wallace
Kim, Sunwook
Harris-Adamson, Carisa
Barr, Alan
Nussbaum, Maury A.
2023-02-10T15:33:31Z
2023-02-10T15:33:31Z
2022-10-11
2023-02-10T14:41:56Z
Conference proceeding
1541-9312
http://hdl.handle.net/10919/113793
https://doi.org/10.1177/1071181322661126
1
66
Nussbaum, Maury [0000-0002-1887-8431]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
SAGE
oai:vtechworks.lib.vt.edu:10919/998242022-02-25T03:17:17Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
A Clustering Refinement Approach for Revealing Urban Spatial Structure from Smart Card Data
Tang, Liyang
Zhao, Yang
Tsui, Kwok-Leung
He, Yuxin
Pan, Liwei
Industrial and Systems Engineering
clustering
cluster ensemble
smart card data
AFC data
passenger flow
urban spatial structure
Facilitated by rapid development of the data-intensive techniques together with communication and sensing technology, we can take advantage of smart card data collected through Automatic Fare Collection (AFC) systems to establish connections between public transit and urban spatial structure. In this paper, with a case study on Shenzhen metro system in China, we investigate the agglomeration pattern of passenger flow among subway stations. Specifically, leveraging inbound and outbound passenger flows at subway stations, we propose a clustering refinement approach based on cluster member stability among multiple clusterings produced by isomorphic or heterogeneous clusterers. Furthermore, we validate and elaborate five clusters of subway stations in terms of regional functionality and urban planning by comparing station clusters with reference to government planning policies and regulations of Shenzhen city. Additionally, outlier stations with ambiguous functionalities are detected using proposed clustering refinement framework.
2020-08-21T15:05:34Z
2020-08-21T15:05:34Z
2020-08-13
2020-08-21T13:50:34Z
Article - Refereed
Tang, L.; Zhao, Y.; Tsui, K.L.; He, Y.; Pan, L. A Clustering Refinement Approach for Revealing Urban Spatial Structure from Smart Card Data. Appl. Sci. 2020, 10, 5606.
http://hdl.handle.net/10919/99824
https://doi.org/10.3390/app10165606
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/258252023-07-12T17:57:36Zcom_10919_24217com_10919_5539col_10919_24292
C-NORTA: A Rejection Procedure for Sampling from the Tail of Bivariate NORTA Distributions
Ghosh, Samik
Pasupathy, R.
Industrial and Systems Engineering
Statistics
Simulation
Random variable generation
Multivariate
Distribution
Correlation
Value-at-risk
Marginals
We propose C-NORTA, an exact algorithm to generate random variates from the tail of a bivariate NORTA random vector. (A NORTA random vector is specified by a pair of marginals and a rank or product-moment correlation, and it is sampled using the popular NORmal-To-Anything procedure.) We first demonstrate that a rejection-based adaptation of NORTA on such constrained random vector generation problems may often be fundamentally intractable. We then develop the C-NORTA algorithm, relying on strategic conditioning of the NORTA vector, followed by efficient approximation and acceptance/rejection steps. We show that, in a certain precise asymptotic sense, the sampling efficiency of C-NORTA is exponentially larger than what is achievable through a naive application of NORTA. Furthermore, for at least a certain class of problems, we show that the acceptance probability within C-NORTA decays only linearly with respect to a defined rarity parameter. The corresponding decay rate achievable through a naive adaptation of NORTA is exponential. We provide directives for efficient implementation.
2014-03-05T14:00:22Z
2014-03-05T14:00:22Z
2012
2014-02-05
Article - Refereed
Soumyadip Ghosh and Raghu Pasupathy. C-NORTA: A Rejection Procedure for Sampling from the Tail of Bivariate NORTA Distributions. INFORMS Journal on Computing 2012 24:2, 295-310. doi: 10.1287/ijoc.1100.0447
1091-9856
http://hdl.handle.net/10919/25825
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.1100.0447
https://doi.org/10.1287/ijoc.1100.0447
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/258312023-07-12T17:57:36Zcom_10919_24217com_10919_5539col_10919_24292
The Nested Event Tree Model with Application to Combating Terrorism
Lunday, B. J.
Sherali, Hanif D.
Glickman, T. S.
Industrial and Systems Engineering
Combating terrorism
Outer approximation
Branch and bound
Global
Optimization
Factorable programs
Mixed-integer models
Computer programming
Global optimization
Resources
Allocation
Risks
In this paper, we model and solve the strategic problem of minimizing the expected loss inflicted by a hostile terrorist organization. An appropriate allocation of certain capability-related, intent-related, vulnerability-related, and consequence-related resources is used to reduce the probabilities of success in the respective attack-related actions and to ameliorate losses in case of a successful attack. We adopt a nested event tree optimization framework and formulate the problem as a specially structured nonconvex factorable program. We develop two branch-and-bound schemes based, respectively, on utilizing a convex nonlinear relaxation and a linear outer approximation, both of which are proven to converge to a global optimal solution. We also design an alternative direct mixed-integer programming model representation for this case, and we investigate a fundamental special-case variant for this scheme that provides a relaxation and affords an optimality gap measure. Several range reduction, partitioning, and branching strategies are proposed, and extensive computational results are presented to study the efficacy of different compositions of these algorithmic ingredients, including comparisons with the commercial software BARON. A sensitivity analysis is also conducted to explore the effect of certain key model parameters.
2014-03-05T14:00:23Z
2014-03-05T14:00:23Z
2010
2014-02-05
Article - Refereed
Lunday, Brian J.; Sherali, Hanif D.; Glickman, Theodore S. The Nested Event Tree Model with Application to Combating Terrorism. INFORMS Journal on Computing 2010 22:4, 620-634. doi: 10.1287/ijoc.1100.0377
1091-9856
http://hdl.handle.net/10919/25831
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.1100.0377
https://doi.org/10.1287/ijoc.1100.0377
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/1049132023-11-29T19:07:35Zcom_10919_5540com_10919_24217com_10919_5539col_10919_71752col_10919_24292
Machine Learning-Enabled 30-Day Readmission Model for Stroke Patients
Darabi, Negar
Hosseinichimeh, Niyousha
Noto, Anthony
Zand, Ramin
Abedi, Vida
ischemic stroke
30-day readmissions
Machine learning
statistical analysis
patient readmission
Background and Purpose: Hospital readmissions impose a substantial burden on the healthcare system. Reducing readmissions after stroke could lead to improved quality of care especially since stroke is associated with a high rate of readmission. The goal of this study is to enhance our understanding of the predictors of 30-day readmission after ischemic stroke and develop models to identify high-risk individuals for targeted interventions.
Methods: We used patient-level data from electronic health records (EHR), five machine learning algorithms (random forest, gradient boosting machine, extreme gradient boosting–XGBoost, support vector machine, and logistic regression-LR), data-driven feature selection strategy, and adaptive sampling to develop 15 models of 30-day readmission after ischemic stroke. We further identified important clinical variables.
Results: We included 3,184 patients with ischemic stroke (mean age: 71 ± 13.90 years, men: 51.06%). Among the 61 clinical variables included in the model, the National Institutes of Health Stroke Scale score above 24, insert indwelling urinary catheter, hypercoagulable state, and percutaneous gastrostomy had the highest importance score. The Model’s AUC (area under the curve) for predicting 30-day readmission was 0.74 (95%CI: 0.64–0.78) with PPV of 0.43 when the XGBoost algorithm was used with ROSE-sampling. The balance between specificity and sensitivity improved through the sampling strategy. The best sensitivity was achieved with LR when optimized with feature selection and ROSE-sampling (AUC: 0.64, sensitivity: 0.53, specificity: 0.69).
Conclusions: Machine learning-based models can be designed to predict 30-day readmission after stroke using structured data from EHR. Among the algorithms analyzed, XGBoost with ROSE-sampling had the best performance in terms of AUC while LR with ROSE-sampling and feature selection had the best sensitivity. Clinical variables highly associated with 30-day readmission could be targeted for personalized interventions. Depending on healthcare systems’ resources and criteria, models with optimized performance metrics can be implemented to improve outcomes.
2021-09-02T17:44:46Z
2021-09-02T17:44:46Z
2021-03-31
Article - Refereed
Darabi N, Hosseinichimeh N, Noto A, Zand R and Abedi V (2021) Machine Learning-Enabled 30-Day Readmission Model for Stroke Patients. Front. Neurol. 12:638267. doi: 10.3389/fneur.2021.638267
http://hdl.handle.net/10919/104913
https://doi.org/10.3389/fneur.2021.638267
12
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Frontiers
oai:vtechworks.lib.vt.edu:10919/1098152022-05-06T07:11:46Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Effects of back-support exoskeleton use on lower limb joint kinematics and kinetics during level walking
Park, Jang-Ho
Lee, Youngjae
Madinei, Saman
Kim, Sun Wook
Nussbaum, Maury A.
Srinivasan, Divya
Assistive device
Gait biomechanics
Hip extension torque
Joint power
We assessed the effects of using a passive back-support exoskeleton (BSE) on lower limb joint kinematics and kinetics during level walking. Twenty young, healthy participants completed level walking trials while wearing a BSE (backX<sup>TM</sup>) with three different levels of hip-extension support torque (i.e., no torque, low, and high) and in a control condition (no-BSE). When hip extension torques were required for gait-initial 0-10% and final 75-100% of the gait cycle-the BSE with high supportive torque provided ~ 10 Nm of external hip extension torque at each hip, resulting in beneficial changes in participants' gait patterns. Specifically, there was a ~ 10% reduction in muscle-generated hip extension torque and ~ 15-20% reduction in extensor power. During the stance-swing transition, however, BSE use produced undesirable changes in lower limb kinematics (e.g., 5-20% increase in ankle joint velocity) and kinetics (e.g., ~ 10% increase in hip flexor, knee extensor, and ankle plantarflexor powers). These latter changes likely stemmed from the need to increase mechanical energy for propelling the leg into the swing phase. BSE use may thus increase the metabolic cost of walking. Whether such use also leads to muscle fatigue and/or postural instability in long-distance walking needs to be confirmed in future work.
2022-05-05T17:55:39Z
2022-05-05T17:55:39Z
2022-04-27
2022-05-05T16:22:01Z
Article - Refereed
0090-6964
10.1007/s10439-022-02973-6 (PII)
http://hdl.handle.net/10919/109815
https://doi.org/10.1007/s10439-022-02973-6
Kim, Sun Wook [0000-0003-3624-1781]
Nussbaum, Maury [0000-0002-1887-8431]
35478066
1573-9686
en
https://www.ncbi.nlm.nih.gov/pubmed/35478066
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Springer
oai:vtechworks.lib.vt.edu:10919/496562023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Applying variance reduction ideas in queuing simulations
Ross, S. M.
Lin, K. Y.
Industrial and Systems Engineering
Generalized concomitant variables
Monte-carlo
Engineering, industrial
Operations research & management science
Statistics & probability
Variance reduction techniques are often underused in simulation studies. In this article, we indicate how certain ones can be efficiently employed when analyzing queuing models. The first technique considered is that of dynamic stratified sampling; the second is the utilization of multiple control variates; the third concerns the replacement of random variables by their conditional expectations when trying to estimate the expected value of a sum of random variables.
2014-07-21T15:49:44Z
2014-07-21T15:49:44Z
2001
2014-07-15
Article - Refereed
Sheldon M. Ross and Kyle Y. Lin (2001). APPLYING VARIANCE REDUCTION IDEAS IN QUEUING SIMULATIONS. Probability in the Engineering and Informational Sciences, 15, pp 481-494. http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=92867&fulltextType=RA&fileId=S0269964801154045
0269-9648
http://hdl.handle.net/10919/49656
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=92867&fulltextType=RA&fileId=S0269964801154045
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Cambridge University Press
oai:vtechworks.lib.vt.edu:10919/998732023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Smart Exercise Application to Improve Leg Function and Short-Term Memory Through Gamelike Lunge Exercises: Development and Evaluation
Noh, Byungjoo
Vasey, Eric
Phillips, Kevin
Jeon, Myounghoon
Yoon, Tejin
Industrial and Systems Engineering
auditory feedback
smart phone
home-based exercise
inertial measurement unit
The purpose of this study was to evaluate the functionality, accuracy, and usability of a novel smart exercise application (SEA). The functionality such as counting lunges, providing task-related auditory feedback, and testing short-term memory was examined while thirteen young adults (six men, age 25.4 ± 8.3 years) performed the lunge exercise with the SEA. The accuracy of logged motion data including angles and accelerations were also tested. Another twenty-five participants (11 men, age 23.2 ± 5.7 years) evaluated the usability of the SEA interest, motivation, convenience, and strength/cognitive benefit via a questionnaire. The SEA assessed the lunge motion correctly, provided auditory feedback, and tested users’ short-term memory as required. High correlations (r = 0.90 to 0.99) with low RMSE (4.85˚ for direction angle, 0.13 to 0.22 m/s² for acceleration) were observed between the sensor output and the reference output. Bland-Altman plot also showed a low discrepancy between each of the two measures. Most participants positively answered all questions about interest (60%), motivation (40%), convenience (80%), strength benefits (92%), and cognitive benefits (88%) of the SEA. The SEA demonstrated accurate kinematic assessment of accelerations and directions, assessed the lunge motion correctly, and created the appropriate auditory feedback on the shortterm memory task. The high rate of positive responses suggested the potential of the application in future use.
2020-08-31T14:21:03Z
2020-08-31T14:21:03Z
2019
Article - Refereed
http://hdl.handle.net/10919/99873
https://doi.org/10.26582/k.51.1.10
51
en
http://creativecommons.org/licenses/by-nc/4.0/
Creative Commons Attribution-NonCommercial 4.0 International
Faculty of Kinesiology, University of Zagreb
oai:vtechworks.lib.vt.edu:10919/1163932023-10-03T13:19:09Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Improving Safety At Highway-Rail Grade Crossings Using In-Vehicle Auditory Alerts
Nadri, Chihab
Lautala, Pasi
Veinott, Elizabeth
Mamun, Tauseef Ibn
Dam, Abhraneil
Jeon, Myounghoon
Despite increased use of lights, gates, and other active warning devices, crashes still happen at Highway-Rail Grade Crossings (HRGCs). To improve safety at HRGCs, we designed an in-vehicle auditory alert (IVAA) and conducted a multi-site driving simulator study to evaluate the effect of the IVAA on driving behavior at HRGCs. The video shows results of the collaboration between Virginia Tech, Michigan Tech, and the Volpe National Transportation Center recruited a total of N = 72 younger drivers. Driver simulator testing showed that the IVAA improved driving behavior near HRGCs, improving gaze behavior at HRGCs. Drivers looked both ways at crossings more often when the IVAA was present. We expect to run additional tests to further improve the IVAA. Our study can contribute to research efforts targeting driving safety at HRGCs.
2023-10-02T14:52:04Z
2023-10-02T14:52:04Z
2023-09-18
2023-10-01T07:51:28Z
Article - Refereed
http://hdl.handle.net/10919/116393
https://doi.org/10.1145/3581961.3609855
en
http://rightsstatements.org/vocab/InC/1.0/
The author(s)
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/1127812022-12-03T08:19:50Zcom_10919_19035com_10919_5539com_10919_24217col_10919_24290col_10919_24292
Effects of Volumetric Augmented Reality Displays on Human Depth Judgments: Implications for Heads-Up Displays in Transportation
Lisle, Lee
Merenda, Coleman
Tanous, Kyle
Kim, Hyungil
Gabbard, Joseph L.
Bowman, Douglas A.
Augmented reality
Human perception
Drivers
Many driving scenarios involve correctly perceiving road elements in depth and manually responding as appropriate. Of late, augmented reality (AR) head-up displays (HUDs) have been explored to assist drivers in identifying road elements, by using a myriad of AR interface designs that include world-fixed graphics perceptually placed in the forward driving scene. Volumetric AR HUDs purportedly offer increased accuracy of distance perception through natural presentation of oculomotor cues as compared to traditional HUDs. In this article, the authors quantify participant performance matching virtual objects to real-world counterparts at egocentric distances of 7-12 meters while using both volumetric and fixed-focal plane AR HUDs. The authors found the volumetric HUD to be associated with faster and more accurate depth judgements at far distance, and that participants performed depth judgements more quickly as the experiment progressed. The authors observed no differences between the two displays in terms of reported simulator sickness or eye strain.
2022-12-02T20:26:02Z
2022-12-02T20:26:02Z
2019
Article - Refereed
http://hdl.handle.net/10919/112781
https://doi.org/10.4018/IJMHCI.2019040101
11
2
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
IGI Global
oai:vtechworks.lib.vt.edu:10919/897422020-10-06T20:24:59Zcom_10919_24217com_10919_5539col_10919_24292
Capturing multi-stage fuzzy uncertainties in hybrid system dynamics and agent-based models for enhancing policy implementation in health systems research
Liu, Shiyong
Triantis, Konstantinos P.
Zhao, Li
Wang, Youfa
Industrial and Systems Engineering
Background In practical research, it was found that most people made health-related decisions not based on numerical data but on perceptions. Examples include the perceptions and their corresponding linguistic values of health risks such as, smoking, syringe sharing, eating energy-dense food, drinking sugar-sweetened beverages etc. For the sake of understanding the mechanisms that affect the implementations of health-related interventions, we employ fuzzy variables to quantify linguistic variable in healthcare modeling where we employ an integrated system dynamics and agent-based model. Methodology In a nonlinear causal-driven simulation environment driven by feedback loops, we mathematically demonstrate how interventions at an aggregate level affect the dynamics of linguistic variables that are captured by fuzzy agents and how interactions among fuzzy agents, at the same time, affect the formation of different clusters(groups) that are targeted by specific interventions. Results In this paper, we provide an innovative framework to capture multi-stage fuzzy uncertainties manifested among interacting heterogeneous agents (individuals) and intervention decisions that affect homogeneous agents (groups of individuals) in a hybrid model that combines an agent-based simulation model (ABM) and a system dynamics models (SDM). Having built the platform to incorporate high-dimension data in a hybrid ABM/SDM model, this paper demonstrates how one can obtain the state variable behaviors in the SDM and the corresponding values of linguistic variables in the ABM. Conclusions This research provides a way to incorporate high-dimension data in a hybrid ABM/SDM model. This research not only enriches the application of fuzzy set theory by capturing the dynamics of variables associated with interacting fuzzy agents that lead to aggregate behaviors but also informs implementation research by enabling the incorporation of linguistic variables at both individual and institutional levels, which makes unstructured linguistic data meaningful and quantifiable in a simulation environment. This research can help practitioners and decision makers to gain better understanding on the dynamics and complexities of precision intervention in healthcare. It can aid the improvement of the optimal allocation of resources for targeted group (s) and the achievement of maximum utility. As this technology becomes more mature, one can design policy flight simulators by which policy/intervention designers can test a variety of assumptions when they evaluate different alternatives interventions.
2019-06-04T16:57:39Z
2019-06-04T16:57:39Z
2018-04-25
Article - Refereed
e0194687
http://hdl.handle.net/10919/89742
https://doi.org/10.1371/journal.pone.0194687
13
4
29694364
1932-6203
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
PLOS
oai:vtechworks.lib.vt.edu:10919/255112023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Collaborative task performance for learning using a virtual environment
Bystrom, Karl-Erik
Barfield, Woodrow S.
Industrial and Systems Engineering
This paper describes a study on the sense of presence and task performance in a virtual environment as affected by copresence (one subject working alone versus two subjects working as partners), level of control (control of movement and control of navigation through the virtual environment), and head tracking. Twenty subjects navigated through six versions of a virtual environment and were asked to identify changes in locations of objects within the environment. After each trial, subjects completed a questionnaire designed to assess their level of presence within the virtual environment. Results indicated that collaboration did not increase the sense of presence in the virtual environment, but did improve the quality of the experience in the virtual environment. Level of control did not affect the sense of presence, but subjects did prefer to control both movement and navigation. Head tracking did not affect the sense of presence, but did contribute to the spatial realism of the virtual environment. Task performance was affected by the presence of another individual, by head tracking, and by level of control, with subjects performing significantly more poorly when they were both alone and without control and head tracking. In addition, a factor analysis indicated that questions designed to assess the subjects' experience in the virtual environment could be grouped into three factors: (1) presence in the virtual environment, (2) quality of the virtual environment, and (3) task difficulty.
2014-02-21T14:20:16Z
2014-02-21T14:20:16Z
1999-08-01
2014-02-05
Article - Refereed
Bystrom, KE; Barfield, W. "Collaborative task performance for learning using a virtual environment," Presence: Teleoperators and Virtual Environments 1999, Vol. 8 No. 4, 435-448 doi: 10.1162/105474699566323
1054-7460
http://hdl.handle.net/10919/25511
http://www.mitpressjournals.org/doi/pdf/10.1162/105474699566323
https://doi.org/10.1162/105474699566323
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
MIT Press
oai:vtechworks.lib.vt.edu:10919/1132302023-01-19T08:13:38Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Recovering from Laboratory-Induced slips and trips causes high levels of lumbar muscle activity and spine loading
Rashedi, Ehsan
Kathawala, Kavish
Abdollahi, Masoud
Alemi, Mohammad Mehdi
Mokhlespour Esfahani, Mohammad Iman
Nussbaum, Maury A.
gait perturbation
spine loading
kinematics
Kinetics
muscle activity
Clinical Research
Rehabilitation
2.1 Biological and endogenous factors
2 Aetiology
Musculoskeletal
Slips, trips, and falls are some of the most substantial and prevalent causes of occupational injuries and fatalities, and these events may contribute to low-back problems. We quantified lumbar kinematics (i.e., lumbar angles relative to pelvis) and kinetics during unexpected slip and trip perturbations, and during normal walking, among 12 participants (6F, 6M). Individual anthropometry, lumbar muscle geometry, and lumbar angles, along with electromyography from 14 lumbar muscles were used as input to a 3D, dynamic, EMG-based model of the lumbar spine. Results indicated that, in comparison with values during normal walking, lumbar range of motion, lumbosacral (L5/S1) loads, and lumbar muscle activations were all significantly higher during the slip and trip events. Maximum L5/S1 compression forces exceeded 2700 N during slip and trip events, compared with ~1100 N during normal walking. Mean values of L5/S1 anteroposterior (930 N), and lateral (800 N) shear forces were also substantially larger than the shear force during the normal walking (230 N). These observed levels of L5/S1 reaction forces, along with high levels of bilateral lumbar muscle activities, suggest the potential for overexertion injuries and tissue damage during unexpected slip and trip events, which could contribute to low back injuries. Outcomes of this study may facilitate the identification and control of specific mechanisms involved with low back disorders consequent to slips or trips.
2023-01-18T14:07:11Z
2023-01-18T14:07:11Z
2023-02
2023-01-17T14:39:48Z
Article - Refereed
1050-6411
http://hdl.handle.net/10919/113230
https://doi.org/10.1016/j.jelekin.2023.102743
68
Nussbaum, Maury [0000-0002-1887-8431]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Elsevier
oai:vtechworks.lib.vt.edu:10919/1144652023-04-12T07:12:54Zcom_10919_24215com_10919_5539com_10919_24217col_10919_24289col_10919_24292
Using eye gaze to reveal cognitive processes and strategies of engineering students when solving spatial rotation and mental cutting tasks
Hsing, Hsiang-Wen
Bairaktarova, Diana
Lau, Nathan
cognitive processes
eye-tracking
first-year engineering students
spatial ability
Background: Spatial problem-solving is an essential skill for success in many engineering disciplines; thus, understanding the cognitive processes involved could help inform the design of training interventions for students trying to improve this skill. Prior research has yet to investigate the differences in cognitive processes between spatial tasks in problem-solving to offer learners timely feedback. Purpose/Hypothesis: In this study, we investigated how different spatial tasks change the cognitive processes and problem-solving strategies used by engineering students with low spatial ability. Design/Method: Study participants completed mental rotation and mental cutting tasks of high and low difficulty. Eye-tracking data were collected and categorized as encoding, transformation, and confirmation cognitive processes. The adoption of either a holistic or piecemeal strategy and response accuracy were also measured. Results: Mental rotation was found to have a higher number of fixations for each cognitive process than the mental cutting task. The holistic strategy was used in both difficulty levels of the mental cutting task, while the piecemeal strategy was adopted for the mental rotation task at a high difficulty level. Only encoding fixations were significantly correlated with accuracy and most strongly correlated with strategy. Conclusion: Encoding is an important cognitive process that could affect subsequent cognitive processes and strategies and could, thus, play an important role in performance. Future development in spatial training should consider how to enhance encoding to aid students with low spatial ability. Educators can utilize gaze metrics and empirical research to provide tailored and timely feedback to learners.
2023-04-11T12:47:33Z
2023-04-11T12:47:33Z
2023-01
Article - Refereed
http://hdl.handle.net/10919/114465
https://doi.org/10.1002/jee.20495
112
1
2168-9830
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
American Society for Engineering Education
oai:vtechworks.lib.vt.edu:10919/1163912023-10-03T13:26:22Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Workshop on Evaluating Augmented Reality in Transportation (EvalAR): A Dialogue Between Researchers and Practitioners
De Oliveira Faria, Nayara
Gabbard, Joseph L.
Burnett, Gary
Meijering, Valerian
The Workshop on Evaluating Augmented Reality in Transportation (EvalAR) brings together researchers and practitioners to address the challenges of evaluating augmented reality head-up displays (AR HUDs) with safety as a priority. With a collaborative approach, this workshop endeavors to shine a spotlight on the unique features of augmented reality, critically examine existing evaluation practices, and collectively identify future hurdles and actionable solutions. Our overarching goal is to collaboratively establish a strategic roadmap that addresses these challenges over the next 3-5 years and beyond. A key highlight of EvalAR is the introduction of the United Nations Economic Commission for Europe (UNECE) and its Working Party on General Safety Provisions to the AutoUI community. This introduction fosters invaluable collaboration and knowledge exchange, enabling researchers and practitioners to leverage each other’s expertise. By facilitating discussions on knowledge and evidence provision, our workshop aims to bolster the academic community’s contributions to regulatory improvements transportation safety. Furthermore, EvalAR actively explores avenues for alignment with global regulations and industry standards, creating a fertile ground for potential collaborations, funding opportunities, and transformative advancements in augmented reality research for enhanced transportation safety.
2023-10-02T14:51:34Z
2023-10-02T14:51:34Z
2023-09-18
2023-10-01T07:51:25Z
Article - Refereed
http://hdl.handle.net/10919/116391
https://doi.org/10.1145/3581961.3609830
en
http://rightsstatements.org/vocab/InC/1.0/
The author(s)
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/792412021-10-08T16:43:31Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539com_10919_23261col_10919_78882col_10919_24292col_10919_23262
Classifying Step and Spin Turns Using Wireless Gyroscopes and Implications for Fall Risk Assessments
Fino, Peter C.
Frames, Christopher W.
Lockhart, Thurmon E.
Mechanical Engineering
Industrial and Systems Engineering
gait
turning
wireless sensors
IMU
fall risk
Recent studies have reported a greater prevalence of spin turns, which are more unstable than step turns, in older adults compared to young adults in laboratory settings. Currently, turning strategies can only be identified through visual observation, either in-person or through video. This paper presents two unique methods and their combination to remotely monitor turning behavior using three uniaxial gyroscopes. Five young adults performed 90° turns at slow, normal, and fast walking speeds around a variety of obstacles while instrumented with three IMUs (attached on the trunk, left and right shank). Raw data from 360 trials were analyzed. Compared to visual classification, the two IMU methods’ sensitivity/specificity to detecting spin turns were 76.1%/76.7% and 76.1%/84.4%, respectively. When the two methods were combined, the IMU had an overall 86.8% sensitivity and 92.2% specificity, with 89.4%/100% sensitivity/specificity at slow speeds. This combined method can be implemented into wireless fall prevention systems and used to identify increased use of spin turns. This method allows for longitudinal monitoring of turning strategies and allows researchers to test for potential associations between the frequency of spin turns and clinically relevant outcomes (e.g., falls) in non-laboratory settings.
2017-09-20T18:22:30Z
2017-09-20T18:22:30Z
2015-05-06
2017-09-20T18:22:30Z
Article - Refereed
Fino, P.C.; Frames, C.W.; Lockhart, T.E. Classifying Step and Spin Turns Using Wireless Gyroscopes and Implications for Fall Risk Assessments. Sensors 2015, 15, 10676-10685.
http://hdl.handle.net/10919/79241
https://doi.org/10.3390/s150510676
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1032892021-10-08T16:43:31Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
A New Robust Multivariate EWMA Dispersion Control Chart for Individual Observations
Ajadi, Jimoh Olawale
Zwetsloot, Inez Maria
Tsui, Kwok-Leung
Industrial and Systems Engineering
individual observations
covariance matrix
non-normality
multivariate dispersion chart
EWMA
A multivariate control chart is proposed to detect changes in the process dispersion of multiple correlated quality characteristics. We focus on individual observations, where we monitor the data vector-by-vector rather than in (rational) subgroups. The proposed control chart is developed by applying the logarithm to the diagonal elements of the estimated covariance matrix. Then, this vector is incorporated in an exponentially weighted moving average (EWMA) statistic. This design makes the chart robust to non-normality in the underlying data. We compare the performance of the proposed control chart with popular alternatives. The simulation studies show that the proposed control chart outperforms the existing procedures when there is an overall decrease in the covariance matrix. In addition, the proposed chart is the most robust to changes in the data distribution, where we focus on small deviations which are difficult to detect. Finally, the compared control charts are applied to two case studies.
2021-05-14T13:14:38Z
2021-05-14T13:14:38Z
2021-05-03
2021-05-13T14:34:46Z
Article - Refereed
Ajadi, J.O.; Zwetsloot, I.M.; Tsui, K.-L. A New Robust Multivariate EWMA Dispersion Control Chart for Individual Observations. Mathematics 2021, 9, 1038.
http://hdl.handle.net/10919/103289
https://doi.org/10.3390/math9091038
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1178362024-02-05T13:15:34Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
The 4th Workshop on Localization vs. Internationalization: Creating an International Survey on Automotive User Interfaces
Stojmenova, Kristina
Lee, Seul Chan
De Oliveira Faria, Nayara
Schroeter, Ronald
Jeon, Myounghoon
Automotive user interfaces
Accessibility
Diversity
International survey
International surveys tend to collect data on attitudes, values and behaviors towards a specific topic from users from multiple countries, providing an insight on the differences and similarities across nations, cultures or geo-political structures. Consequently, international surveys provide important information about the diversity of the user's needs, values and preferences, which have to be taken into consideration when creating products and services as widely used as the personal automobile. The workshop will focus on the design and development of an international survey on automotive user interfaces on a global scale. It will try to identify the most important aspects related to automotive user interfaces, which should be addressed in the survey. It will also prepare a strategy for its international distribution and create a plan for comprehensive data collection. Lastly, it will try to outline venues and communication channels for the survey dissemination, with the goal of achieving wide visibility.
2024-02-02T18:27:09Z
2024-02-02T18:27:09Z
2022-09-17
Conference proceeding
9781450394284
https://hdl.handle.net/10919/117836
https://doi.org/10.1145/3544999.3549911
Jeon, Myounghoon [0000-0003-2908-671X]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/522732023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. I. Research of Working Group 11, Accredited Standards Committee S12, noise
Royster, Julia D.
Berger, Elliott H.
Merry, Carol J.
Nixon, Charles W.
Franks, John R.
Behar, Alberto
Casali, John G.
Dixon-Ernst, Christine
Kieper, Ronald W.
Mozo, Ben T.
Ohlin, Doug
Royster, Larry H.
Industrial and Systems Engineering
Hearing protection
Audiometry
Calibration
Machinery noise
Hearing
This paper describes research conducted by Working Group 11 of Accredited Standards Committee S12, Noise, to develop procedures to estimate the field performance of hearing protection devices (HPDs). Current standardized test methods overestimate the attenuation achieved by workers in everyday use on the job. The goal was to approximate the amount of attenuation that can be achieved by noise-exposed populations in well-managed real-world hearing conservation programs, while maintaining acceptable interlaboratory measurement variability. S12/WG11 designed two new laboratory-based protocols for measuring real-ear attenuation at threshold, with explicit procedures for subject selection, training, supervision, and HPD fitting. After pilot-testing, S12/WG11 conducted a full-scale study of three types of earplugs and one earmuff tested by four independent laboratories using both protocols. The protocol designated as ''subject-fit'' assessed the attenuation achieved by subjects who were experienced in threshold audiometry, but naive with respect to the use of hearing protection, when they fit HPDs by following manufacturers' instructions without any experimenter assistance. The attenuation results from the subject-fit method corresponded more closely to real-world data than results from the other protocol tested, which allowed the experimenter to coach subjects in HPD use, Comparisons of interlaboratory measurement variability for the subject-fit procedure to previous interlaboratory studies using other protocols indicated that the measurements with the new procedure are at least as reproducible as those obtained with existing standardized methods. Therefore, the subject-fit protocol was selected for consideration for use in future revisions of HPD attenuation test standards. Copyright 1996 Acoustical Society of America.
2015-05-13T22:30:07Z
2015-05-13T22:30:07Z
1996-03-01
2015-05-12
Article - Refereed
Royster, J. D., Berger, E. H., Merry, C. J., Nixon, C. W., Franks, J. R., Behar, A., Casali, J. G., Dixon-Ernst, C., Kieper, R. W., Mozo, B. T., Ohlin, D., & Royster, L. H. (1996). Development of a new standard laboratory protocol for estimating the field attenuation of hearing protection devices. I. Research of Working Group 11, Accredited Standards Committee S12, noise. Journal of the Acoustical Society of America, 99(3), 1506-1526. doi: 10.1121/1.414729
0001-4966
http://hdl.handle.net/10919/52273
http://scitation.aip.org/content/asa/journal/jasa/99/3/10.1121/1.414729
https://doi.org/10.1121/1.414729
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Acoustical Society of America
oai:vtechworks.lib.vt.edu:10919/1175002024-03-18T10:52:54Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Cognitive Workload of Novice Forklift Truck Drivers in VR-based Training
Jamshid Nezhad Zahabi, Saman
Shafiqul Islam, Md
Kim, Sunwook
Lau, Nathan
Nussbaum, Maury A.
Lim, Sol
Virtual reality
Training
Forklift drivers
There is increasing use of Virtual Reality (VR) to train forklift truck operators but a lack of sufficient understanding of how cognitive workload changes with respect to different task demands in VR-based training. In this study, 19 novice participants completed three forklift driving lessons with varying difficulty levels (low, medium, and high) using a VR simulator. To examine the effect of repeated training on cognitive workload, two sessions were repeated by participants using the same procedures. Cognitive workload was assessed with objective (electroencephalogram [EEG] activity) and subjective (NASA-TLX) measurements. EEG theta power and NASA-TLX (mental workload) scores were significantly higher for high than low difficulty levels. However, both EEG and NASA-TLX responses were reduced with repeated training in the second session. These findings highlight the effectiveness of EEG in continuous monitoring of workload variation caused by task difficulty and implementing training programs to moderate cognitive workload for forklift operators.
2024-01-22T13:52:33Z
2024-01-22T13:52:33Z
2023-10-19
Conference proceeding
2169-5067
https://hdl.handle.net/10919/117500
https://doi.org/10.1177/21695067231192864
67
1
Nussbaum, Maury [0000-0002-1887-8431]
Kim, Sun Wook [0000-0003-3624-1781]
1071-1813
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
SAGE
oai:vtechworks.lib.vt.edu:10919/919202023-11-29T19:08:13Zcom_10919_5540com_10919_24217com_10919_5539col_10919_71752col_10919_24292
Exploration of different classes of metrics to characterize motor variability during repetitive symmetric and asymmetric lifting tasks
Sedighi, Alireza
Nussbaum, Maury A.
Industrial and Systems Engineering
low-back-pain
movement variability
sample entropy
torso kinematics/kinetics
approximate entropy
experienced workers
healthy
Performance
strategies
disorders
The substantial kinematic degrees-of-freedom available in human movement lead to inherent variations in a repetitive movement, or motor variability (MV). Growing evidence suggests that characterizing MV permits a better understanding of potential injury mechanisms. Several diverse methods, though, have been used to quantify MV, but limited evidence exists regarding the merits of these methods in the occupational context. In this work, we explored different classes of methods for characterizing MV during symmetric and asymmetric box lifting tasks. Kinematic MV of both the whole-body center-of-mass (COM) and the box were quantified, using metrics derived from a linear method (Standard Deviation), a non-linear method (Sample Entropy; an index of movement regularity), and a novel application of an equifinality method (Goal Equivalent Manifold; an index related to the set of effective motor solutions). Our results suggest that individuals manipulate regularity and the set of effective motor solutions to overcome unwanted motor noises related to the COM. These results, together with earlier evidence, imply that individuals may prioritize stability over variability with increasing task difficulty. Task performance also appeared to deteriorate with decreasing variability and regularity of the COM. We conclude that diverse metrics of MV may be complimentary to reveal differences in MV.
2019-07-23T16:50:04Z
2019-07-23T16:50:04Z
2019-07-08
Article - Refereed
2045-2322
9821
http://hdl.handle.net/10919/91920
https://doi.org/10.1038/s41598-019-46297-3
9
31285469
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Springer Nature
oai:vtechworks.lib.vt.edu:10919/1098182023-11-29T19:08:15Zcom_10919_78629com_10919_78628com_10919_5540com_10919_24217com_10919_5539col_10919_78630col_10919_71752col_10919_24292
Benefits of integrated screening and vaccination for infection control
Rabil, Marie Jeanne
Tunc, Sait
Bish, Douglas R.
Bish, Ebru K.
Vaccination
Immunization
Virus testing
COVID-19
College campuses
Importance: Screening and vaccination are essential in the fight against infectious diseases, but need to be integrated and customized based on community and disease characteristics.
Objective: To develop effective screening and vaccination strategies, customized for a college campus, to reduce COVID-19 infections, hospitalizations, deaths, and peak hospitalizations.
Design, setting, and participants: We construct a compartmental model of disease spread under vaccination and routine screening, and study the efficacy of four mitigation strategies (routine screening only, vaccination only, vaccination with partial or full routine screening), and a no-intervention strategy. The study setting is a hypothetical college campus of 5,000 students and 455 faculty members during the Fall 2021 academic semester, when the Delta variant was the predominant strain. For sensitivity analysis, we vary the screening frequency, daily vaccination rate, initial vaccine coverage, and screening and vaccination compliance; and consider scenarios that represent low/medium/high transmission and test efficacy. Model parameters come from publicly available or published sources.
Results: With low initial vaccine coverage (30% in our study), even aggressive vaccination and screening result in a high number of infections: 1,020 to 2,040 (1,530 to 2,480) with routine daily (every other day) screening of the unvaccinated; 280 to 900 with daily screening extended to the newly vaccinated in base- and worst-case scenarios, which respectively consider reproduction numbers of 4.75 and 6.75 for the Delta variant.
Conclusion: Integrated vaccination and routine screening can allow for a safe opening of a college when both the vaccine effectiveness and the initial vaccine coverage are sufficiently high. The interventions need to be customized considering the initial vaccine coverage, estimated compliance, screening and vaccination capacity, disease transmission and adverse outcome rates, and the number of infections/peak hospitalizations the college is willing to tolerate.
2022-05-06T12:17:20Z
2022-05-06T12:17:20Z
2022-04-21
Article - Refereed
http://hdl.handle.net/10919/109818
https://doi.org/10.1371/journal.pone.0267388
17
4
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
PLOS
oai:vtechworks.lib.vt.edu:10919/1137002023-02-08T08:12:40Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Online Structural Change-point Detection of High-dimensional Streaming Data via Dynamic Sparse Subspace Learning
Xu, Ruiyu
Wu, Jianguo
Yue, Xiaowei
Li, Yongxiang
High-dimensional time series
Manifold learning
Multiple change-point model
Subspace clustering
GRAPHICAL MODELS
ALGORITHM
SELECTION
NETWORKS
High-dimensional streaming data are becoming increasingly ubiquitous in many fields. They often lie in multiple low-dimensional subspaces, and the manifold structures may change abruptly on the time scale due to pattern shift or occurrence of anomalies. However, the problem of detecting the structural changes in a real-time manner has not been well studied. To fill this gap, we propose a dynamic sparse subspace learning approach for online structural change-point detection of high-dimensional streaming data. A novel multiple structural change-point model is proposed and the asymptotic properties of the estimators are investigated. A tuning method based on Bayesian information criterion and change-point detection accuracy is proposed for penalty coefficients selection. An efficient Pruned Exact Linear Time based algorithm is proposed for online optimization and change-point detection. The effectiveness of the proposed method is demonstrated through several simulation studies and a real case study on gesture data for motion tracking. Supplementary materials for this article are available online.
2023-02-07T17:34:21Z
2023-02-07T17:34:21Z
2022-03-30
2023-02-05T03:28:50Z
Article - Refereed
0040-1706
http://hdl.handle.net/10919/113700
https://doi.org/10.1080/00401706.2022.2046171
Yue, Xiaowei [0000-0001-6019-0940]
1537-2723
en
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000777095200001&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Taylor & Francis
oai:vtechworks.lib.vt.edu:10919/258362023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
An Algorithm for Fast Generation of Bivariate Poisson Random Vectors
Shin, K.
Pasupathy, R.
Industrial and Systems Engineering
Statistics
Simulation
Random variable generation
Multivariate
Distribution
Correlation
Marginals
We present the "trivariate reduction extension" (TREx)-an exact algorithm for the fast generation of bivariate Poisson random vectors. Like the normal-to-anything (NORTA) procedure, TREx has two phases: a preprocessing phase when the required algorithm parameters are identified, and a generation phase when the parameters identified during the preprocessing phase are used to generate the desired Poisson vector. We prove that the proposed algorithm covers the entire range of theoretically feasible correlations, and we provide efficient-computation directives and rigorous bounds for truncation error control. We demonstrate through extensive numerical tests that TREx, being a specialized algorithm for Poisson vectors, has a preprocessing phase that is uniformly a hundred to a thousand times faster than a fast implementation of NORTA. The generation phases of TREx and NORTA are comparable in speed, with that of TREx being marginally faster. All code is publicly available.
2014-03-05T14:00:24Z
2014-03-05T14:00:24Z
2010
2014-02-05
Article - Refereed
Shin, Kaeyoung; Pasupathy, Raghu. An Algorithm for Fast Generation of Bivariate Poisson Random Vectors. INFORMS Journal on Computing 2010 22:1, 81-92. doi: 10.1287/ijoc.1090.0332
1091-9856
http://hdl.handle.net/10919/25836
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.1090.0332
https://doi.org/10.1287/ijoc.1090.0332
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/1051682023-11-29T16:17:33Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_5524col_10919_70873col_10919_24292col_10919_89575
Examining senior drivers' attitudes toward advanced driver assistance systems after naturalistic exposure
Liang, Dan
Lau, Nathan
Baker, Stephanie Ann
Antin, Jonathan F.
ADAS
Focus group
Naturalistic driving study
Technology acceptance
Topic modeling
Background and Objectives: The increasing number of senior drivers may introduce new road risks due to age-related declines in physical and cognitive abilities. Advanced driver assistance systems (ADAS) have been proposed as solutions to minimize age-related declines, thereby increasing both senior safety and mobility. This study examined factors that influence seniors' attitudes toward adopting ADAS after significant exposure to the technology in naturalistic settings. Research Design and Methods: This study recruited 18 senior drivers aged 70-79 to drive vehicles equipped with ADAS for 6 weeks in their own environments. Afterward, each participant was enrolled in 1 of the 3 focus group sessions to discuss their changes in attitude toward ADAS based on their driving experiences. We applied structural topic modeling (STM) on the focus group transcripts to reveal key topics deemed important to seniors. Results: STM revealed 5 topics of importance for seniors. In order of prevalence, these were (i) safety, (ii) confidence concerning ADAS, (iii) ADAS functionality, (iv) user interface/usability, and (v) non-ADAS-related features. Based on topics and associated keywords, seniors perceived safety improvement with ADAS but expressed concerns about its limitations in coping with adverse driving conditions. Experience and training were suggested for improving seniors' confidence in ADAS. Blind spot alert and adaptive cruise control received the most discussion regarding perceived safety and comfort. Discussion and Implications: This study indicated that promoting road safety for senior drivers through ADAS is feasible. Acceptance and appropriate use of ADAS may be supported through intuitive and senior-friendly user interfaces, in-depth training programs, and owner's manuals specifically designed and tested for senior drivers.
2021-10-05T16:53:21Z
2021-10-05T16:53:21Z
2020-01-01
2021-10-05T16:53:19Z
Article - Refereed
2399-5300
PMC7302428
igaa017 (PII)
http://hdl.handle.net/10919/105168
https://doi.org/10.1093/geroni/igaa017
4
3
Lau, Nathan [0000-0003-2235-9527]
32582868
2399-5300
en
https://www.ncbi.nlm.nih.gov/pubmed/32582868
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Oxford University Press
oai:vtechworks.lib.vt.edu:10919/1075682024-03-12T15:59:32Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Usability and user acceptance of an arm-support exoskeleton in automotive assembly: Results of a long-term field evaluation
Kim, Sunwook
Nussbaum, Maury A.
Smets, Marty
2022-01-12T15:58:46Z
2022-01-12T15:58:46Z
2021-09-01
2022-01-12T15:58:44Z
Conference proceeding
1071-1813
http://hdl.handle.net/10919/107568
https://doi.org/10.1177/1071181321651165
65
1
Nussbaum, Maury [0000-0002-1887-8431]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
SAGE
oai:vtechworks.lib.vt.edu:10919/1053892023-11-29T11:25:18Zcom_10919_5com_10919_25799com_10919_25796com_10919_24217com_10919_5539col_10919_70873col_10919_25797col_10919_24292
High-resolution computational modeling of immune responses in the gut
Verma, Meghna
Bassaganya-Riera, Josep
Leber, Andrew
Tubau-Juni, Nuria
Hoops, Stefan
Abedi, Vida
Chen, Xi
Hontecillas, Raquel
Life Sciences & Biomedicine
Biology
agent-based model
ordinary differential equation
Gaussian process
Helicobacter pylori
high-performance computing
metamodel
sensitivity analysis
immune system
dendritic cells
macrophages
HELICOBACTER-PYLORI
SENSITIVITY-ANALYSIS
HEALTH
Background: Helicobacter pylori causes gastric cancer in 1-2% of cases but is also beneficial for protection against allergies and gastroesophageal diseases. An estimated 85% of H. pylori-colonized individuals experience no detrimental effects. To study the mechanisms promoting host tolerance to the bacterium in the gastrointestinal mucosa and systemic regulatory effects, we investigated the dynamics of immunoregulatory mechanisms triggered by H. pylori using a high-performance computing-driven ENteric Immunity SImulator multiscale model. Immune responses were simulated by integrating an agent-based model, ordinary, and partial differential equations. Results: The outputs were analyzed using 2 sequential stages: The first used a partial rank correlation coefficient regression-based and the second a metamodel-based global sensitivity analysis. The influential parameters screened from the first stage were selected to be varied for the second stage. The outputs from both stages were combined as a training dataset to build a spatiotemporal metamodel. The Sobol indices measured time-varying impact of input parameters during initiation, peak, and chronic phases of infection. The study identified epithelial cell proliferation and epithelial cell death as key parameters that control infection outcomes. In silico validation showed that colonization with H. pylori decreased with a decrease in epithelial cell proliferation, which was linked to regulatory macrophages and tolerogenic dendritic cells. Conclusions: The hybrid model of H. pylori infection identified epithelial cell proliferation as a key factor for successful colonization of the gastric niche and highlighted the role of tolerogenic dendritic cells and regulatory macrophages in modulating the host responses and shaping infection outcomes.
2021-10-14T18:46:03Z
2021-10-14T18:46:03Z
2019-06-01
2021-10-14T18:45:58Z
Article - Refereed
2047-217X
5513894 (PII)
http://hdl.handle.net/10919/105389
https://doi.org/10.1093/gigascience/giz062
8
6
Hontecillas-Magarzo, Raquel [0000-0003-2942-6294]
Chen, Xi [0000-0001-7965-9198]
31185494
2047-217X
en
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000475755000008&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Oxford University Press
oai:vtechworks.lib.vt.edu:10919/971072021-10-08T16:43:32Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
Risk Factors for Postural and Functional Balance Impairment in Patients with Chronic Obstructive Pulmonary Disease
Park, Jaekwan K.
Deutz, Nicolaas E. P.
Cruthirds, Clayton L.
Kirschner, Sarah K.
Park, Hangue
Madigan, Michael L.
Engelen, Mariëlle P. K. J.
Industrial and Systems Engineering
COPD
postural sway
Berg Balance Scale
functional balance
Reduced balance function has been observed during balance challenging conditions in the chronic obstructive pulmonary disease (COPD) population and is associated with an increased risk of falls. This study aimed to examine postural balance during quiet standing with eyes open and functional balance in a heterogeneous group of COPD and non-COPD (control) subjects, and to identify risk factors underlying balance impairment using a large panel of methods. In COPD and control subjects, who were mostly overweight and sedentary, postural and functional balance were assessed using center-of-pressure displacement in anterior-posterior (AP) and medio-lateral (ML) directions, and the Berg Balance Scale (BBS), respectively. COPD showed 23% greater AP sway velocity (<i>p</i> = 0.049). The presence of oxygen therapy, fat mass, reduced neurocognitive function, and the presence of (pre)diabetes explained 71% of the variation in postural balance in COPD. Transcutaneous oxygen saturation, a history of exacerbation, and gait speed explained 83% of the variation in functional balance in COPD. Neurocognitive dysfunction was the main risk factor for postural balance impairment in the control group. This suggests that specific phenotypes of COPD patients can be identified based on their type of balance impairment.
2020-03-02T13:30:15Z
2020-03-02T13:30:15Z
2020-02-24
2020-03-02T12:42:02Z
Article - Refereed
Park, J.K.; Deutz, N.E.P.; Cruthirds, C.L.; Kirschner, S.K.; Park, H.; Madigan, M.L.; Engelen, M.P.K.J. Risk Factors for Postural and Functional Balance Impairment in Patients with Chronic Obstructive Pulmonary Disease. J. Clin. Med. 2020, 9, 609.
http://hdl.handle.net/10919/97107
https://doi.org/10.3390/jcm9020609
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1081442023-07-12T17:57:37Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Coverage Path Planning for Robotic Quality Inspection With Control on Measurement Uncertainty
Liu, Yinhua
Zhao, Wenzheng
Liu, Hongpeng
Wang, Yinan
Yue, Xiaowei
Industrial Engineering & Automation
0906 Electrical and Electronic Engineering
0910 Manufacturing Engineering
0913 Mechanical Engineering
The optical scanning gauges mounted on the robots are commonly used in quality inspection, such as verifying the dimensional specification of sheet structures. Coverage path planning (CPP) significantly influences the accuracy and efficiency of robotic quality inspection. Traditional CPP strategies focus on minimizing the number of viewpoints or traveling distance of robots under the condition of full coverage inspection. The measurement uncertainty when collecting the scanning data is less considered in the free-form surface inspection. To address this problem, a novel CPP method with the optimal viewpoint sampling strategy is proposed to incorporate the measurement uncertainty of key measurement points (MPs) into free-form surface inspection. At first, the feasible ranges of measurement uncertainty are calculated based on the tolerance specifications of the MPs. The initial feasible viewpoint set is generated considering the measurement uncertainty and the visibility of MPs. Then, the inspection cost function is built to evaluate the number of selected viewpoints and the average measurement uncertainty in the field of views of all the selected viewpoints. Afterward, an enhanced rapidly exploring random tree algorithm is proposed for viewpoint sampling using the inspection cost function and CPP optimization. Case studies, including simulation tests and inspection experiments, have been conducted to evaluate the effectiveness of the proposed method. Results show that the scanning precision of key MPs is significantly improved compared with the benchmark method.
2022-02-05T15:28:07Z
2022-02-05T15:28:07Z
2022-01-01
2022-02-05T15:28:03Z
Article - Refereed
1083-4435
http://hdl.handle.net/10919/108144
https://doi.org/10.1109/TMECH.2022.3142756
PP
99
Yue, Xiaowei [0000-0001-6019-0940]
1941-014X
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1163962023-10-03T13:09:13Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Am I Really Angry? The Influence of Anger Intensities on Young Drivers' Behaviors
Wang, Manhua
Jeon, Myounghoon
Anger can lead to aggressive driving and other negative behaviors. While previous studies treated anger as a single dimension, the present research proposed that anger has distinct intensities and aimed to understand the effects of different anger intensities on driver behaviors. After developing the anger induction materials, we conducted a driving simulator study with 30 participants and assigned them to low, medium, and high anger intensity groups. We found that drivers with low anger intensity were not able to recognize their emotions and exhibited speeding behaviors, while drivers with medium and high anger intensities might be aware of their anger along with its adverse effects and then adjusted their longitudinal control. However, angry drivers generally exhibited compromised lateral control indicated by steering and lane-keeping behaviors. Our findings shed light on the potentially different influences of anger intensities on young drivers’ behaviors, especially the importance of anger recognition for intervention solutions.
2023-10-02T14:52:45Z
2023-10-02T14:52:45Z
2023-09-18
2023-10-01T07:51:33Z
Article - Refereed
http://hdl.handle.net/10919/116396
https://doi.org/10.1145/3581961.3609884
en
http://rightsstatements.org/vocab/InC/1.0/
The author(s)
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/1126402022-11-16T08:12:54Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Effects of Arm-Support Exoskeletons on Kinematics and Subjective Assessments During a Static Task
Ojelade, Aanuoluwapo
Kelson, Denean D.
Srinivasan, Divya D.
Kim, Sunwook S.
Smets, Marty
Nussbaum, Maury A.
2022-11-15T19:00:04Z
2022-11-15T19:00:04Z
2021-09
2022-11-12T16:24:43Z
Conference proceeding
1071-1813
http://hdl.handle.net/10919/112640
https://doi.org/10.1177/1071181321651187
65
1
Nussbaum, Maury [0000-0002-1887-8431]
Kim, Sun Wook [0000-0003-3624-1781]
1071-1813
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Human Factors and Ergonomics Society
oai:vtechworks.lib.vt.edu:10919/1145682023-04-20T07:12:24Zcom_10919_24217com_10919_5539col_10919_24292
Feedforward control of thermal history in laser powder bed fusion: Toward physics-based optimization of processing parameters
Riensche, Alex
Bevans, Benjamin D.
Smoqi, Ziyad
Yavari, Reza
Krishnan, Ajay
Gilligan, Josie
Piercy, Nicholas
Cole, Kevin
Rao, Prahalada
Feedforward process control
Laser powder bed fusion
Thermal history simulations
Graph theory
Physics -based parameter optimization
We developed and applied a model-driven feedforward control approach to mitigate thermal-induced flaw formation in laser powder bed fusion (LPBF) additive manufacturing process. The key idea was to avert heat buildup in a LPBF part before it is printed by adapting process parameters layer-by-layer based on insights from a physics-based thermal simulation model. The motivation being to replace cumbersome empirical build-and-test parameter optimization with a physics-guided strategy. The approach consisted of three steps: prediction, analysis, and correction. First, the temperature distribution of a part was predicted rapidly using a graph theory-based computational thermal model. Second, the model-derived thermal trends were analyzed to isolate layers of potential heat buildup. Third, heat buildup in affected layers was corrected before printing by adjusting process parameters optimized through iterative simulations. The effectiveness of the approach was demonstrated experimentally on two separate build plates. In the first build plate, termed fxed processing, ten different nickel alloy 718 parts were produced under constant processing conditions. On a second identical build plate, called con-trolled processing, the laser power and dwell time for each part was adjusted before printing based on thermal simulations to avoid heat buildup. To validate the thermal model predictions, the surface tem-perature of each part was tracked with a calibrated infrared thermal camera. Post-process the parts were examined with non-destructive and destructive materials characterization techniques. Compared to fixed processing, parts produced under controlled processing showed superior geometric accuracy and resolu-tion, finer grain size, increased microhardness, and reduced surface roughness.(c) 2022 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
2023-04-19T14:59:02Z
2023-04-19T14:59:02Z
2022-12
Article - Refereed
111351
http://hdl.handle.net/10919/114568
https://doi.org/10.1016/j.matdes.2022.111351
224
1873-4197
en
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Elsevier
oai:vtechworks.lib.vt.edu:10919/1004682023-07-12T17:57:37Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
Trunk Flexion Monitoring among Warehouse Workers Using a Single Inertial Sensor and the Influence of Different Sampling Durations
Porta, Micaela
Pau, Massimiliano
Orrù, Pier Francesco
Nussbaum, Maury A.
Industrial and System Engineering
inertial measurement unit (IMU)
manual material handling task (MMH)
trunk flexion
Trunk flexion represents a risk factor for the onset of low-back disorders, yet limited quantitative data exist regarding flexion exposures in actual working conditions. In this study, we evaluated the potential of using a single inertial measurement unit (IMU) to classify trunk flexion, in terms of amplitude, frequency, and duration, and assessed the influence of alternative time durations on exposure results. Twelve warehouse workers were monitored during two hours of an actual shift while wearing a single IMU on their low back. Trunk flexion data were reduced using exposure variation analysis integrated with recommended exposure thresholds. Workers spent 5.1% of their working time with trunk flexion of 30–60° and 2.3% with flexion of 60–90°. Depending on the level of acceptable error, relatively shorter monitoring periods (up to 50 min) might be sufficient to characterize trunk flexion exposures. Future work is needed, however, to determine if these results generalize to other postural exposures and tasks.
2020-10-13T17:17:58Z
2020-10-13T17:17:58Z
2020-09-28
2020-10-13T13:24:24Z
Porta, M.; Pau, M.; Orrù, P.F.; Nussbaum, M.A. Trunk Flexion Monitoring among Warehouse Workers Using a Single Inertial Sensor and the Influence of Different Sampling Durations. Int. J. Environ. Res. Public Health 2020, 17, 7117.
http://hdl.handle.net/10919/100468
en
MDPI
oai:vtechworks.lib.vt.edu:10919/496292023-07-12T17:57:37Zcom_10919_78629com_10919_78628com_10919_24217com_10919_5539col_10919_78630col_10919_24292
Development of an individual-based model for polioviruses: implications of the selection of network type and outcome metrics
Rahmandad, Hazhir
Hu, K.
Tebbens, R. J. D.
Thompson, Kimberly M.
Industrial and Systems Engineering
Disease transmission
Individual-based model
Outbreak response
Poliovirus
Infectious diseases
Pandemic influenza
Risk-management
Spread
Poliomyelitis
Epidemiology
Dynamics
Polio
Outbreaks
Eradication
Public, environmental & occupational health
Infectious diseases
We developed an individual-based (IB) model to explore the stochastic attributes of state transitions, the heterogeneity of the individual interactions, and the impact of different network structure choices on the poliovirus transmission process in the context of understanding the dynamics of outbreaks. We used a previously published differential equation-based model to develop the IB model and inputs. To explore the impact of different types of networks, we implemented a total of 26 variations of six different network structures in the IB model. We found that the choice of network structure plays a critical role in the model estimates of cases and the dynamics of outbreaks. This study provides insights about the potential use of an IB model to support policy analyses related to managing the risks of polioviruses and shows the importance of assumptions about network structure.
2014-07-21T15:49:37Z
2014-07-21T15:49:37Z
2011-06-01
2014-07-15
Article - Refereed
Rahmandad, H.; Hu, K.; Tebbens, R. J. D.; Thompson, K. M., "Development of an individual-based model for polioviruses: implications of the selection of network type and outcome metrics," Epidemiol. Infect. (2011), 139, 836-848. DOI: 10.1017/s0950268810001676
0950-2688
http://hdl.handle.net/10919/49629
http://journals.cambridge.org/action/displayAbstract?fromPage=online&aid=8266579&fulltextType=RA&fileId=S0950268810001676
https://doi.org/10.1017/s0950268810001676
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Cambridge University Press
oai:vtechworks.lib.vt.edu:10919/1180662024-02-20T12:01:49Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_24212com_10919_5553col_10919_70873col_10919_24292col_10919_24333
Teleoperator-Robot-Human Interaction in Manufacturing: Perspectives from Industry, Robot Manufacturers, and Researchers
Kim, Sunwook
Hernandez, Ivan
Nussbaum, Maury A.
Lim, Sol
Human-robot interaction
distributed manufacturing
manufacturing performance
remote human-robot interaction
OCCUPATIONAL APPLICATIONS: Industrial robots have become an important aspect in modern industry. In the context of human-robot collaboration, enabling teleoperated robots to work in close proximity to local/onsite humans can provide new opportunities to improve human engagement in a distributed workplace. Interviews with industry stakeholders highlighted several potential benefits of such teleoperator-robot-human collaboration (tRHC), including the application of tRHC to tasks requiring both expertise and manual dexterity (e.g., maintenance and highly skilled tasks in sectors including construction, manufacturing, and healthcare), as well as opportunities to expand job accessibility for individuals with disabilities and older individuals. However, interviewees also indicated potential challenges of tRHC, particularly related to human perception (e.g., perceiving remote environments), safety, and trust. Given these challenges, and the current limited information on the practical value and implementation of tRHC, we propose several future research directions, with a focus on human factors and ergonomics, to help realize the potential benefits of tRHC.
2024-02-20T15:59:13Z
2024-02-20T15:59:13Z
2024-02-08
Article - Refereed
2472-5838
https://hdl.handle.net/10919/118066
https://doi.org/10.1080/24725838.2024.2310301
Kim, Sun Wook [0000-0003-3624-1781]
Nussbaum, Maury [0000-0002-1887-8431]
Lim, Sol [0000-0001-5569-9312]
Hernandez, Jorge [0000-0002-3141-7525]
38328969
2472-5846
en
https://www.ncbi.nlm.nih.gov/pubmed/38328969
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Informa
oai:vtechworks.lib.vt.edu:10919/973142020-10-15T20:34:50Zcom_10919_78629com_10919_78628com_10919_24217com_10919_5539col_10919_78630col_10919_24292
Performance Assessment of a Water Supply System under the Impact of Climate Change and Droughts: Case Study of the Washington Metropolitan Area
Bhatkoti, Roma
Triantis, Konstantinos P.
Moglen, Glenn E.
Sabounchi, Nasim S.
Industrial and Systems Engineering
Fresh water demand is rising due to factors such as population growth, economic development, and land use changes. At the same time, climate change is rendering the water supply even more uncertain for the future. Due to recurring water restrictions and increasing water-related fees triggered by droughts and water shortages, there is a widespread, growing discomfort with respect to future water availability. Among key stakeholders and local policy makers, this has led to an increased interest in modeling the availability of water resources, with the aim of developing and implementing the appropriate water resource infrastructure and management strategies. This paper examines the Washington metropolitan area (WMA) water supply system and uses a system dynamics approach as a planning tool to make an exploratory assessment of the adequacy of the study area's water supply system to meet future water demand under the influence of substantial droughts and climate change. This assessment finds that the study area is self-sufficient under normal climate conditions during the entire planning horizon but that it will be strained under moderately severe droughts. On the basis of the temperature, streamflow and precipitation projections made by climate change models specific to the WMA region, climate change is expected to improve the water supply reliability. However, climate change has uncertainty associated with it. One of the four climate models for the Potomac River basin projects a decrease in the precipitation and streamflow, which may result in a reduction in the water supply and the system's reliability. Regulating the price and the system losses are valuable tools that can be leveraged. But these policy interventions require stakeholder participation (price regulation) and capital investments (reduction of distribution losses). Finally, system reliability can also be improved by increasing water supplies.
2020-03-11T17:21:22Z
2020-03-11T17:21:22Z
2018-09
Article - Refereed
1076-0342
5018002
http://hdl.handle.net/10919/97314
https://doi.org/10.1061/(ASCE)IS.1943-555X.0000435
24
3
1943-555X
en
http://creativecommons.org/publicdomain/zero/1.0/
Creative Commons CC0 1.0 Universal Public Domain Dedication
oai:vtechworks.lib.vt.edu:10919/1176862024-01-26T03:02:09Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Generative Agent-Based Modeling: Unveiling Social System Dynamics through Coupling Mechanistic Models with Generative Artificial Intelligence
Ghaffarzadegan, Navid
Majumdar, Aritra
Williams, Ross
Hosseinichimeh, Niyousha
Generative agent
generative artificial intelligence
agent-based model
generative agent-based model
system dynamics
ChatGPT
We discuss the emerging new opportunity for building feedback-rich computational models of social systems using generative artificial intelligence. Referred to as Generative Agent-Based Models (GABMs), such individual-level models utilize large language models to represent human decision-making in social settings. We provide a GABM case in which human behavior can be incorporated in simulation models by coupling a mechanistic model of human interactions with a pre-trained large language model. This is achieved by introducing a simple GABM of social norm diffusion in an organization. For educational purposes, the model is intentionally kept simple. We examine a wide range of scenarios and the sensitivity of the results to several changes in the prompt. We hope the article and the model serve as a guide for building useful dynamic models of various social systems that include realistic human reasoning and decision-making.
2024-01-25T18:02:54Z
2024-01-25T18:02:54Z
2024-01
Article - Refereed
Ghaffarzadegan, N., Majumdar, A., Williams, R., & Hosseinichimeh, N. (2024). Generative agent‐based modeling: an introduction and tutorial. System Dynamics Review. https://doi.org/10.1002/sdr.1761
https://hdl.handle.net/10919/117686
https://doi.org/10.1002/sdr.1761
abs/2309.11456
Ghaffarzadegan, Navid [0000-0003-3632-8588]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1178722024-02-06T14:40:35Zcom_10919_24217com_10919_5539com_10919_24210com_10919_5553com_10919_24262com_10919_5559col_10919_24292col_10919_24285col_10919_24344
Why Similar Policies Resulted In Different COVID-19 Outcomes: How Responsiveness And Culture Influenced Mortality Rates
Lim, Tse Yang
Xu, Ran
Ruktanonchai, Nick
Saucedo, Omar
Childs, Lauren M.
Jalali, Mohammad S.
Rahmandad, Hazhir
Ghaffarzadegan, Navid
In the first two years of the COVID-19 pandemic, per capita mortality varied by more than a hundredfold across countries, despite most implementing similar nonpharmaceutical interventions. Factors such as policy stringency, gross domestic product, and age distribution explain only a small fraction of mortality variation. To address this puzzle, we built on a previously validated pandemic model in which perceived risk altered societal responses affecting SARS-CoV-2 transmission. Using data from more than 100 countries, we found that a key factor explaining heterogeneous death rates was not the policy responses themselves but rather variation in responsiveness. Responsiveness measures how sensitive communities are to evolving mortality risks and how readily they adopt nonpharmaceutical interventions in response, to curb transmission.We further found that responsiveness correlated with two cultural constructs across countries: uncertainty avoidance and power distance. Our findings show that more responsive adoption of similar policies saves many lives, with important implications for the design and implementation of responses to future outbreaks.
2024-02-06T17:55:58Z
2024-02-06T17:55:58Z
2023-12
Article - Refereed
https://hdl.handle.net/10919/117872
https://doi.org/10.1377/hlthaff.2023.00713
42
12
en
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Health Affairs
oai:vtechworks.lib.vt.edu:10919/1016282020-12-24T08:30:59Zcom_10919_24217com_10919_5539col_10919_24292
Consistent individual motor variability traits demonstrated by females performing a long-cycle assembly task under conditions differing in temporal organisation
Jackson, Jennie A.
Srinivasan, Divya
Mathiassen, Svend Erik
Industrial and Systems Engineering
Motor control
Trapezius electromyography
Upper arm elevation angle
Research suggests an association between motor variability (MV) during repetitive work and work-related musculoskeletal disorders (MSDs). However, whether MV is a consistent individual trait, even across working conditions or tasks, remains unknown. This study assessed whether individual MV traits were consistent during complex work performed under different temporal conditions. Fifteen women performed cyclic assembly under four conditions differing in pace and organisation (line-type, batch-type). MV of trapezius muscle activity and upper arm elevation was quantified and partitioned into variance components. For all MV metrics, a non-zero between-subjects variance was found, indicating consistent individual MV traits across conditions. Variance between subjects was higher for electromyography (EMG) MV metrics compared with kinematic metrics. Our results showed individuals exhibited consistent MV traits across working conditions differing in pace and production process. Further research is needed to understand whether MV is an individual predictive factor for MSD onset or progression.
2020-12-23T20:06:36Z
2020-12-23T20:06:36Z
2020-05
Article - Refereed
0003-6870
103046
http://hdl.handle.net/10919/101628
https://doi.org/10.1016/j.apergo.2020.103046
85
32174342
1872-9126
en
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
oai:vtechworks.lib.vt.edu:10919/1050302022-04-08T04:54:07Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_18629col_10919_24292
Influencing factors of Barthel index scores among the community-dwelling elderly in Hong Kong: a random intercept model
Pan, Hao
Zhao, Yang
Wang, Hailiang
Li, Xinyue
Leung, Eman
Chen, Frank
Cabrera, Javier
Tsui, Kwok-Leung
Background
Barthel Index (BI) is one of the most widely utilized tools for assessing functional independence in activities of daily living. Most existing BI studies used populations with specific diseases (e.g., Alzheimer’s and stroke) to test prognostic factors of BI scores; however, the generalization of these findings was limited when the target populations varied.
Objectives
The aim of the present study was to utilize electronic health records (EHRs) and data mining techniques to develop a generic procedure for identifying prognostic factors that influence BI score changes among community-dwelling elderly.
Methods
Longitudinal data were collected from 113 older adults (81 females; mean age = 84 years, SD = 6.9 years) in Hong Kong elderly care centers. Visualization technologies were used to align annual BI scores with individual EHRs chronologically. Linear mixed-effects (LME) regression was conducted to model longitudinal BI scores based on socio-demographics, disease conditions, and features extracted from EHRs.
Results
The visualization presented a decline in BI scores changed by time and health history events. The LME model yielded a conditional R2 of 84%, a marginal R2 of 75%, and a Cohen’s f2 of 0.68 in the design of random intercepts for individual heterogeneity. Changes in BI scores were significantly influenced by a set of socio-demographics (i.e., sex, education, living arrangement, and hobbies), disease conditions (i.e., dementia and diabetes mellitus), and EHRs features (i.e., event counts in allergies, diagnoses, accidents, wounds, hospital admissions, injections, etc.).
Conclusions
The proposed visualization approach and the LME model estimation can help to trace older adults’ BI score changes and identify the influencing factors. The constructed long-term surveillance system provides reference data in clinical practice and help healthcare providers manage the time, cost, data and human resources in community-dwelling settings.
2021-09-20T11:46:28Z
2021-09-20T11:46:28Z
2021-09-06
2021-09-12T03:07:54Z
Article - Refereed
BMC Geriatrics. 2021 Sep 06;21(1):484
http://hdl.handle.net/10919/105030
https://doi.org/10.1186/s12877-021-02422-4
en
http://creativecommons.org/licenses/by/4.0/
The Author(s)
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1135612023-11-29T19:08:59Zcom_10919_5com_10919_25799com_10919_5540com_10919_24217com_10919_5539col_10919_70873col_10919_71752col_10919_24292
A cyclical wildfire pattern as the outcome of a coupled human natural system
Farkhondehmaal, Farshad
Ghaffarzadegan, Navid
temporal patterns
risk
forest
climate
hazard
simulation
mitigation
prediction
dynamics
savanna
clinical research
Over the past decades, wildfire has imposed a considerable cost on natural resources and human lives. In many regions, annual wildfire trends show puzzling oscillatory patterns with increasing amplitudes for burned areas over time. This paper aims to examine the potential causes of such patterns by developing and examining a dynamic simulation model that represents interconnected social and natural dynamics in a coupled system. We develop a generic dynamic model and, based on simulation results, postulate that the interconnection between human and natural subsystems is a source of the observed cyclical patterns in wildfires in which risk perception regulates activities that can result in more fire and development of vulnerable properties. Our simulation-based policy analysis points to a non-linear characteristic of the system, which rises due to the interconnections between the human side and the natural side of the system. This has a major policy implication: in contrast to studies that look for the most effective policy to contain wildfires, we show that a long-term solution is not a single action but is a combination of multiple actions that simultaneously target both human and natural sides of the system.
2023-01-30T18:09:00Z
2023-01-30T18:09:00Z
2022-03-28
2023-01-28T15:46:50Z
Article - Refereed
2045-2322
10.1038/s41598-022-08730-y (PII)
http://hdl.handle.net/10919/113561
https://doi.org/10.1038/s41598-022-08730-y
12
1
Ghaffarzadegan, Navid [0000-0003-3632-8588]
35347175
2045-2322
en
http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000774204500033&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=930d57c9ac61a043676db62af60056c1
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Nature Portfolio
oai:vtechworks.lib.vt.edu:10919/1133962024-03-12T15:59:32Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
A preliminary decision tree modeling of factors that determine readiness to use exoskeletons in construction
Moore, Albert
Kim, Sunwook
Srinivasan, Divya
Nussbaum, Maury A.
Ojelade, Aanuoluwapo
Harris-Adamson, Carisa
Gutierrez Contreras, Nancy
Barr, Alan
Rempel, David
Exoskeletons
Construction
2023-01-24T17:51:43Z
2023-01-24T17:51:43Z
2021-09
2023-01-24T14:04:07Z
Conference proceeding
2169-5067
http://hdl.handle.net/10919/113396
https://doi.org/10.1177/1071181321651014
65
1
Nussbaum, Maury [0000-0002-1887-8431]
Kim, Sun Wook [0000-0003-3624-1781]
1071-1813
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
SAGE
oai:vtechworks.lib.vt.edu:10919/1003012022-04-08T04:54:07Zcom_10919_24217com_10919_5539col_10919_24292
Design and Implementation Factors for Performance Measurement in Non-profit Organizations: A Literature Review
Treinta, Fernanda T.
Moura, Louisi Francis
Almeida Prado Cestari, Jose M.
de Lima, Edson Pinheiro
Deschamps, Fernando
Gouvea da Costa, Sergio Eduardo
Van Aken, Eileen M.
Munik, Juliano
Leite, Luciana R.
Industrial and Systems Engineering
non-profit organizations
performance measurement systems
literature review
bibliometric analysis
social network
Purpose:Performance measurement systems (PMS) in Non-profit Organizations (NPOs) are more complex than in for-profit organizations. NPOs have an orientation toward social mission and values, and they consider not only organizational efficiency and viability, but also the social impact of the organization. This research provides a comprehensive synthesis of PMSs in NPOs. Design/Methodology/Approach:Using a literature review, supported by bibliometric and network analyses. A paper set of 240 articles related to this research field is examined. Topics that are the most prevalent in this research area and their interrelationships are identified, presenting an outline of current efforts. Findings:Despite the descriptive analyses for the paper set, a framework is proposed for organizing the design-implementation factors of PMSs in non-profit organizations, identifying the main requirements for their successful development. Originality/Value:Investigation on performance measurement in non-profit organizations is still in its early stages of development with many opportunities to further develop the field. Conceptual frameworks and models, as well as specific theories, are being generated for this field of research, and the process of adapting models from the general field of performance measurement is taking place. The meta-framework that organizes the main research topics of PMS in non-profit organizations and the framework that consolidates factors that influence the design-implementation of PMSs in non-profit organizations developed represents this paper contribution.
2020-10-07T17:45:17Z
2020-10-07T17:45:17Z
2020-08-07
Article - Refereed
1664-1078
1799
http://hdl.handle.net/10919/100301
https://doi.org/10.3389/fpsyg.2020.01799
11
32903643
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/258262023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Optimal Sampling Laws for Stochastically Constrained Simulation Optimization on Finite Sets
Hunter, S. R.
Pasupathy, R.
Industrial and Systems Engineering
Constrained simulation optimization
Optimal allocation
Ranking and
Selection
Systems
Consider the context of selecting an optimal system from among a finite set of competing systems, based on a "stochastic" objective function and subject to multiple "stochastic" constraints. In this context, we characterize the asymptotically optimal sample allocation that maximizes the rate at which the probability of false selection tends to zero. Since the optimal allocation is the result of a concave maximization problem, its solution is particularly easy to obtain in contexts where the underlying distributions are known or can be assumed. We provide a consistent estimator for the optimal allocation and a corresponding sequential algorithm fit for implementation. Various numerical examples demonstrate how the proposed allocation differs from competing algorithms.
2014-03-05T14:00:22Z
2014-03-05T14:00:22Z
2013
2014-02-05
Article - Refereed
Susan R. Hunter and Raghu Pasupathy. Optimal Sampling Laws for Stochastically Constrained Simulation Optimization on Finite Sets. INFORMS Journal on Computing 2013 25:3, 527-542. doi: 10.1287/ijoc.1120.0519
1091-9856
http://hdl.handle.net/10919/25826
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.1120.0519
https://doi.org/10.1287/ijoc.1120.0519
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/1117562022-09-09T07:13:42Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
A Systematic Review of Wearable Sensor-Based Technologies for Fall Risk Assessment in Older Adults
Chen, Manting
Wang, Hailiang
Yu, Lisha
Yeung, Eric Hiu Kwong
Luo, Jiajia
Tsui, Kwok-Leung
Zhao, Yang
Falls have been recognized as the major cause of accidental death and injury in people aged 65 and above. The timely prediction of fall risks can help identify older adults prone to falls and implement preventive interventions. Recent advancements in wearable sensor-based technologies and big data analysis have spurred the development of accurate, affordable, and easy-to-use approaches to fall risk assessment. The objective of this study was to systematically assess the current state of wearable sensor-based technologies for fall risk assessment among community-dwelling older adults. Twenty-five of 614 identified research articles were included in this review. A comprehensive comparison was conducted to evaluate these approaches from several perspectives. In general, these approaches provide an accurate and effective surrogate for fall risk assessment. The accuracy of fall risk prediction can be influenced by various factors such as sensor location, sensor type, features utilized, and data processing and modeling techniques. Features constructed from the raw signals are essential for predictive model development. However, more investigations are needed to identify distinct, clinically interpretable features and develop a general framework for fall risk assessment based on the integration of sensor technologies and data modeling.
2022-09-08T17:03:51Z
2022-09-08T17:03:51Z
2022-09-07
2022-09-08T13:24:10Z
Article - Refereed
Chen, M.; Wang, H.; Yu, L.; Yeung, E.H.K.; Luo, J.; Tsui, K.-L.; Zhao, Y. A Systematic Review of Wearable Sensor-Based Technologies for Fall Risk Assessment in Older Adults. Sensors 2022, 22, 6752.
http://hdl.handle.net/10919/111756
https://doi.org/10.3390/s22186752
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1091112022-03-07T13:28:11Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
The Effect of Context Switching, Focal Switching Distance, Binocular and Monocular Viewing, and Transient Focal Blur on Human Performance in Optical See-Through Augmented Reality
Arefin, Mohammed S.
Phillips, Nate
Plopski, Alexander
Gabbard, Joseph L.
Swan, J. Edward
Software Engineering
0801 Artificial Intelligence and Image Processing
0802 Computation Theory and Mathematics
In optical see-through augmented reality (AR), information is often distributed between real and virtual contexts, and often appears at different distances from the user. To integrate information, users must repeatedly switch context and change focal distance. If the user’s task is conducted under time pressure, they may attempt to integrate information while their eye is still changing focal distance, a phenomenon we term transient focal blur. Previously, Gabbard, Mehra, and Swan (2018) examined these issues, using a text-based visual search task on a one-eye optical see-through AR display. This paper reports an experiment that partially replicates and extends this task on a custom-built AR Haploscope. The experiment examined the effects of context switching, focal switching distance, binocular and monocular viewing, and transient focal blur on task performance and eye fatigue. Context switching increased eye fatigue but did not decrease performance. Increasing focal switching distance increased eye fatigue and decreased performance. Monocular viewing also increased eye fatigue and decreased performance. The transient focal blur effect resulted in additional performance decrements, and is an addition to knowledge about AR user interface design issues.
2022-03-04T19:40:42Z
2022-03-04T19:40:42Z
2022-01-01
2022-03-04T19:40:32Z
Article - Refereed
1077-2626
http://hdl.handle.net/10919/109111
https://doi.org/10.1109/TVCG.2022.3150503
Gabbard, Joseph [0000-0002-7488-676X]
35167470
1941-0506
en
https://www.ncbi.nlm.nih.gov/pubmed/35167470
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
IEEE
oai:vtechworks.lib.vt.edu:10919/1037622023-11-29T19:09:29Zcom_10919_8195com_10919_25799com_10919_5540com_10919_24217com_10919_5539col_10919_78882col_10919_71752col_10919_24292
Conjoining Wymore’s Systems Theoretic Framework and the DEVS Modeling Formalism: Toward Scientific Foundations for MBSE
Wach, Paul
Zeigler, Bernard P.
Salado, Alejandro
Industrial and Systems Engineering
model-based systems engineering
MBSE
modeling & simulation
model and simulation-based systems engineering
digital engineering
digital transformation
DEVS
The objective of this research article is to re-introduce some of the concepts provided by A. Wayne Wymore in his mathematical theory of Model-Based Systems Engineering, discuss why his framework might have not been adopted, and define a potential path to modernize the framework for practical application in the digital age. The dense mathematical theory has never been converted to a practical form. We propose a path to modernization by creating a metamodel of Wymore’s mathematical theory of MBSE. This enables explaining the concepts in simple to understand terms and shows the internal consistency provided by the theory. Furthermore, the metamodel allows for conversion of the theory into software application, for which we show some initial results that open the research to the art of the possible. In recognition of limitation of the theory, we make the case for a merger of the theoretical framework with the enhanced formalism of Discrete Event System Specification (DEVS). This will establish a path toward the scientific foundations for MBSE to enable future implementations of the complementary pairing and their empirical results.
2021-06-10T19:35:29Z
2021-06-10T19:35:29Z
2021-05-27
2021-06-10T13:46:13Z
Article - Refereed
Wach, P.; Zeigler, B.P.; Salado, A. Conjoining Wymore’s Systems Theoretic Framework and the DEVS Modeling Formalism: Toward Scientific Foundations for MBSE. Appl. Sci. 2021, 11, 4936.
http://hdl.handle.net/10919/103762
https://doi.org/10.3390/app11114936
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1089832022-03-01T13:16:04Zcom_10919_5com_10919_25799com_10919_19035com_10919_5539com_10919_24217col_10919_70873col_10919_24290col_10919_24292
Utilizing Immersive Technologies in the Air Traffic Control Domain
Bajaj, Shivani
Jorquera, Andrew
Duff, Sammy
Patrick, Rafael
McCarley, Jason
Immersive Technology
The Federal Aviation Administration (FAA) holds a vital role in the United States, employing over 14,000 Air Traffic Control/Management (ATC/ATM) specialists responsible for managing roughly 43,000 flights each day. ATC education “wash-out” rates have shown that there is a disconnect between the training process and the implementation of cognitively demanding, safety-critical ATC duties. The purpose of this research was to investigate if, how, and where immersive technologies (i.e., augmented, virtual, and mixed reality) could be helpful within the ATC/ATM educational domain. To accomplish the overall research goal, subject matter expert (SME) interviews were conducted and a potential educational tool was developed and tested in two distinct research phases. Eighteen (N = 18) subjects volunteered to participate throughout both phases, and the tool was rated to be above average meaning the tool is usable in its current form; however, further development is suggested and expected
2022-03-01T04:00:56Z
2022-03-01T04:00:56Z
2021-05-01
2022-03-01T04:00:54Z
Conference proceeding
http://hdl.handle.net/10919/108983
2021 Proceedings
Patrick, Rafael [0000-0002-7503-2184]
en
https://corescholar.libraries.wright.edu/
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
CORE Scholar - Wright University
oai:vtechworks.lib.vt.edu:10919/1153482023-11-29T01:43:57Zcom_10919_5com_10919_25799com_10919_24240com_10919_5549com_10919_19035com_10919_5539com_10919_24217col_10919_70873col_10919_24337col_10919_24290col_10919_24292
Formal definition of the MARS method for quantifying the unique target class discoveries of selected machine classifiers
Restrepo, Felipe
Mali, Namrata
Abrahams, Alan
Ractham, Peter
Binary classification
Classifier comparative uniqueness
Classifier performance evaluation
Classifier selection optimization
Machine learning
Conventional binary classification performance metrics evaluate either general measures (accuracy, F score) or specific aspects (precision, recall) of a model's classifying ability. As such, these metrics, derived from the model's confusion matrix, provide crucial insight regarding classifier-data interactions. However, modern- day computational capabilities have allowed for the creation of increasingly complex models that share nearly identical classification performance. While traditional performance metrics remain as essential indicators of a classifier's individual capabilities, their ability to differentiate between models is limited. In this paper, we present the methodology for MARS (Method for Assessing Relative Sensitivity/ Specificity) ShineThrough and MARS Occlusion scores, two novel binary classification performance metrics, designed to quantify the distinctiveness of a classifier's predictive successes and failures, relative to alternative classifiers. Being able to quantitatively express classifier uniqueness adds a novel classifier-classifier layer to the process of model evaluation and could improve ensemble model-selection decision making. By calculating both conventional performance measures, and proposed MARS metrics for a simple classifier prediction dataset, we demonstrate that the proposed metrics' informational strengths synergize well with those of traditional metrics, delivering insight complementary to that of conventional metrics.
2023-06-06T16:59:23Z
2023-06-06T16:59:23Z
2022-07
2023-06-06T14:34:41Z
Article - Refereed
2046-1402
PMC9350436
http://hdl.handle.net/10919/115348
https://doi.org/10.12688/f1000research.110567.2
11
Abrahams, Alan [0000-0002-4884-3192]
35967970
2046-1402
en
https://www.ncbi.nlm.nih.gov/pubmed/35967970
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
F1000 Research
oai:vtechworks.lib.vt.edu:10919/1115332023-11-29T15:23:11Zcom_10919_5com_10919_25799com_10919_18738com_10919_5539com_10919_24217com_10919_24210com_10919_5553com_10919_110083col_10919_70873col_10919_23145col_10919_24292col_10919_24285col_10919_110084
Collaborative Multi-Robot Multi-Human Teams in Search and Rescue
Williams, Ryan K.
Abaid, Nicole
McClure, James
Lau, Nathan
Heintzman, Larkin
Hashimoto, Amanda
Wang, Tianzi
Patnayak, Chinmaya
Kumar, Akshay
Robots such as unmanned aerial vehicles (UAVs) deployed for search and rescue (SAR) can explore areas where human searchers cannot easily go and gather information on scales that can transform SAR strategy. Multi-UAV teams therefore have the potential to transform SAR by augmenting the capabilities of human teams and providing information that would otherwise be inaccessible. Our research aims to develop new theory and technologies for field deploying autonomous UAVs and managing multi-UAV teams working in concert with multi-human teams for SAR. Specifically, in this paper we summarize our work in progress towards these goals, including: (1) a multi-UAV search path planner that adapts to human behavior; (2) an in-field distributed computing prototype that supports multi-UAV computation and communication; (3) behavioral modeling that yields spatially localized predictions of lost person location; and (4) an interface between human searchers and UAVs that facilitates human-UAV interaction over a wide range of autonomy.
2022-08-16T15:10:10Z
2022-08-16T15:10:10Z
2022-04-30
2022-08-10T13:44:19Z
Conference proceeding
http://hdl.handle.net/10919/111533
Lau, Nathan [0000-0003-2235-9527]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1115252022-08-16T07:13:50Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Toward a Consequential Validity Perspective for Selecting Participant Groups in Testing and Evaluation Studies for Complex System
Lau, Nathan
Boring, Ronald L.
Wright, Julia
Barber, Daniel
Testing and evaluation
Consequential validity
Testing and evaluation of technology design for complex systems cannot readily attain conclusive results. This is because skilled professionals are often not available for testing while non-professionals may not be capable of operating the actual systems or high-fidelity simulators. Thus, practitioners and applied scientists can be challenged with decisions on selecting participant groups, which can severely constrain choices in the experimental tasks. This article presents the perspective of consequential validity, highlighting that general validity or rules to participant selection probably do not exist. Most importantly, the validity of a testing method or an empirical finding critically rests on the decisions of interest that must take into account nuances or idiosyncrasies of specific situations and desired outcomes. This perspective stands in contrast to how the literature predominantly portrays validity of testing methods or empirical findings as universal rather than focusing on outcomes within the confines of the study methods. The perspective of consequential validity calls for studies on how classical metrics of reliability and validity could manifest in consequence of specific decisions informed by empirical testing.
2022-08-15T19:36:32Z
2022-08-15T19:36:32Z
2022-07-26
2022-08-13T05:26:50Z
Conference proceeding
http://hdl.handle.net/10919/111525
https://doi.org/10.54941/ahfe1001487
Lau, Nathan [0000-0003-2235-9527]
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/848892023-11-29T19:09:38Zcom_10919_8195com_10919_25799com_10919_5540com_10919_24217com_10919_5539com_10919_23274col_10919_78882col_10919_71752col_10919_24292col_10919_23275
Preferred Placement and Usability of a Smart Textile System vs. Inertial Measurement Units for Activity Monitoring
Mokhlespour Esfahani, Mohammad Iman
Nussbaum, Maury A.
Industrial and Systems Engineering
School of Biomedical Engineering and Sciences
smart textile system
inertial measurement unit
wearable sensor
usability
placement
smart shirt
smart socks
Wearable sensors and systems have become increasingly popular in recent years. Two prominent wearable technologies for human activity monitoring are smart textile systems (STSs) and inertial measurement units (IMUs). Despite ongoing advances in both, the usability aspects of these devices require further investigation, especially to facilitate future use. In this study, 18 participants evaluate the preferred placement and usability of two STSs, along with a comparison to a commercial IMU system. These evaluations are completed after participants engaged in a range of activities (e.g., sitting, standing, walking, and running), during which they wear two representatives of smart textile systems: (1) a custom smart undershirt (SUS) and commercial smart socks; and (2) a commercial whole-body IMU system. We first analyze responses regarding the usability of the STS, and subsequently compared these results to those for the IMU system. Participants identify a short-sleeved shirt as their preferred activity monitor. In additional, the SUS in combination with the smart socks is rated superior to the IMU system in several aspects of usability. As reported herein, STSs show promise for future applications in human activity monitoring in terms of usability.
2018-08-22T14:40:21Z
2018-08-22T14:40:21Z
2018-08-01
2018-08-22T08:32:03Z
Article - Refereed
Mokhlespour Esfahani, M.I.; Nussbaum, M.A. Preferred Placement and Usability of a Smart Textile System vs. Inertial Measurement Units for Activity Monitoring. Sensors 2018, 18, 2501.
http://hdl.handle.net/10919/84889
https://doi.org/10.3390/s18082501
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/258302023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
Information theory and the finite-time behavior of the simulated annealing algorithm: Experimental results
Fleischer, M.
Jacobson, Sheldon H.
Industrial and Systems Engineering
Logic modeling and computation
Information theory
Simulated annealing
Entropy
This article presents an empirical approach that demonstrates a theoretical connection between (information theoretic) entropy measures and the finite-time performance of the simulated annealing algorithm. The methodology developed reads to several computational approaches for creating problem instances useful in testing and demonstrating the entropy/performance connection: use of generic configuration spaces, polynomial transformations between NP-hard problems, and modification of penalty parameters. In particular, the computational results show that higher entropy measures are associated with superior finite-time performance of the simulated annealing algorithm.
2014-03-05T14:00:23Z
2014-03-05T14:00:23Z
1999
2014-02-05
Article
Fleischer, M; Jacobson, SH. Information theory and the finite-time behavior of the simulated annealing algorithm: Experimental results. INFORMS Journal on Computing 1999 11:1, 35-43. doi: 10.1287/ijoc.11.1.35
1091-9856
http://hdl.handle.net/10919/25830
http://pubsonline.informs.org/doi/pdf/10.1287/ijoc.11.1.35
https://doi.org/10.1287/ijoc.11.1.35
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
INFORMS
oai:vtechworks.lib.vt.edu:10919/867752023-11-29T19:09:39Zcom_10919_5540com_10919_24217com_10919_5539col_10919_71752col_10919_24292
Late retirement, early careers, and the aging of U.S. science and engineering professors
Ghaffarzadegan, Navid
Xu, Ran
Industrial and Systems Engineering
Studies of rescuing early-career scientists often take narrow approaches and focus on PhD students or postdoc populations. In a multi-method systems approach, we examine the inter-relations between the two ends of the pipeline and ask: what are the effects of late retirement on aging and hiring in academia? With a simulation model, we postulate that the decline in the retirement rate in academia contributes to the aging pattern through two mechanisms: (a) direct effect: longer stay of established professors, and (b) indirect effect: a hiring decline in tenure-track positions. Late retirement explains more than half of the growth in average age and brings about 20% decline in hiring. We provide empirical evidence based on the natural experimental set-up of the removal of mandatory retirement in the 1990s.
2019-01-18T19:04:15Z
2019-01-18T19:04:15Z
2018-12-26
Article - Refereed
Citation: Ghaffarzadegan N, Xu R (2018) Late retirement, early careers, and the aging of U.S. science and engineering professors. PLoS ONE 13 (12): e0208411. https://doi.org/10.1371/journal. pone.0208411
http://hdl.handle.net/10919/86775
https://doi.org/10.1371/journal.pone.0208411
13
12
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
PLOS
oai:vtechworks.lib.vt.edu:10919/1068992021-12-10T08:33:05Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539com_10919_84995com_10919_5553col_10919_78882col_10919_24292col_10919_84996
Macrophage Activation in the Dorsal Root Ganglion in Rats Developing Autotomy after Peripheral Nerve Injury
Xu, Xiang
Zhou, Xijie
Du, Jian
Liu, Xiao
Qing, Liming
Johnson, Blake N.
Jia, Xiaofeng
Autotomy, self-mutilation of a denervated limb, is common in animals after peripheral nerve injury (PNI) and is a reliable proxy for neuropathic pain in humans. Understanding the occurrence and treatment of autotomy remains challenging. The objective of this study was to investigate the occurrence of autotomy in nude and Wistar rats and evaluate the differences in macrophage activation and fiber sensitization contributing to the understanding of autotomy behavior. Autotomy in nude and Wistar rats was observed and evaluated 6 and 12 weeks after sciatic nerve repair surgery. The numbers of macrophages and the types of neurons in the dorsal root ganglion (DRG) between the two groups were compared by immunofluorescence studies. Immunostaining of T cells in the DRG was also assessed. Nude rats engaged in autotomy with less frequency than Wistar rats. Autotomy symptoms were also relatively less severe in nude rats. Immunofluorescence studies revealed increased macrophage accumulation and activation in the DRG of Wistar rats. The percentage of NF200+ neurons was higher at 6 and 12 weeks in Wistar rats compared to nude rats, but the percentage of CGRP+ neurons did not differ between two groups. Additionally, macrophages were concentrated around NF200-labeled A fibers. At 6 and 12 weeks following PNI, CD4+ T cells were not found in the DRG of the two groups. The accumulation and activation of macrophages in the DRG may account for the increased frequency and severity of autotomy in Wistar rats. Our results also suggest that A fiber neurons in the DRG play an important role in autotomy.
2021-12-09T19:55:30Z
2021-12-09T19:55:30Z
2021-11-26
2021-12-09T14:31:59Z
Article - Refereed
Xu, X.; Zhou, X.; Du, J.; Liu, X.; Qing, L.; Johnson, B.N.; Jia, X. Macrophage Activation in the Dorsal Root Ganglion in Rats Developing Autotomy after Peripheral Nerve Injury. Int. J. Mol. Sci. 2021, 22, 12801.
http://hdl.handle.net/10919/106899
https://doi.org/10.3390/ijms222312801
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1157212023-07-12T07:12:53Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Cro-Create: Weaving Sound Using Crochet Gestures
Bruen, Jacqueline
Kwon, Henry
Jeon, Myounghoon
Cro-Create is a crochet gesture recognition sonifier for individual and collaborative use. In single user mode, Cro-Create directly scales and maps numerical palm orientation values detected by a motion sensor to sound. In dual user mode, the system affords users with additional auditory feedback by detecting when two users’ gestures are synchronized by segmenting the gestural procedure of making a stitch in crochet into three stages and utilizing a dynamic time warping algorithm to classify and recognize these stages; when the system determines that both users have produced the same gesture, the sonification is complemented by a distinguishable chord. Through this demonstration we introduce our tool to share procedural state for the physical craftmaking process, crochet, through sound.
2023-07-11T13:45:42Z
2023-07-11T13:45:42Z
2023-06-19
2023-07-01T08:03:20Z
Article - Refereed
http://hdl.handle.net/10919/115721
https://doi.org/10.1145/3591196.3596816
en
http://rightsstatements.org/vocab/InC/1.0/
The author(s)
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/988502022-04-08T04:42:07Zcom_10919_8195com_10919_25799com_10919_24216com_10919_5539com_10919_111731com_10919_5555com_10919_24217com_10919_23913col_10919_18629col_10919_24286col_10919_111733col_10919_24292col_10919_23920
Perturbation-based balance training targeting both slip- and trip-induced falls among older adults: a randomized controlled trial
Allin, Leigh J.
Brolinson, Per Gunnar
Beach, Briana M.
Kim, Sunwook
Nussbaum, Maury A.
Roberto, Karen A.
Madigan, Michael L.
Center for Gerontology
Biomedical Engineering and Mechanics
Industrial and Systems Engineering
Institute for Society, Culture and Environment
Background
Falls are the leading cause of injuries among older adults. Perturbation-based balance training (PBT) is an innovative approach to fall prevention that aims to improve the reactive balance response following perturbations such as slipping and tripping. Many of these PBT studies have targeted reactive balance after slipping or tripping, despite both contributing to a large proportion of older adult falls. The goal of this randomized controlled trial was to evaluate the effects of PBT targeting slipping and tripping on laboratory-induced slips and trips. To build upon prior work, the present study included: 1) a control group; 2) separate training and assessment sessions; 3) PBT methods potentially more amenable for use outside the lab compared to methods employed elsewhere, and 4) individualized training for older adult participants.
Methods
Thirty-four community-dwelling, healthy older adults (61–75 years) were assigned to PBT or a control intervention using minimization. Using a parallel design, reactive balance (primary outcome) and fall incidence were assessed before and after four sessions of BRT or a control intervention involving general balance exercises. Assessments involved exposing participants to an unexpected laboratory-induced slip or trip. Reactive balance and fall incidence were compared between three mutually-exclusive groups: 1) baseline participants who experienced a slip (or trip) before either intervention, 2) post-control participants who experienced a slip (or trip) after the control intervention, and 3) post-PBT participants who experienced a slip (or trip) after PBT. Neither the participants nor investigators were blinded to group assignment.
Results
All 34 participants completed all four sessions of their assigned intervention, and all 34 participants were analyzed. Regarding slips, several measures of reactive balance were improved among post-PBT participants when compared to baseline participants or post-control participants, and fall incidence among post-PBT participants (18%) was lower than among baseline participants (80%). Regarding trips, neither reactive balance nor fall incidence differed between groups
Conclusions
PBT targeting slipping and tripping improved reactive balance and fall incidence after laboratory-induced slips. Improvements were not observed after laboratory-induced trips. The disparity in efficacy between slips and trip may have resulted from differences in dosage and specificity between slip and trip training.
Trial registration
Name of Clinical Trial Registry: clinicaltrials.gov
Trial Registration number: NCT04308239.
Date of Registration: March 13, 2020 (retrospectively registered).
2020-06-15T11:49:05Z
2020-06-15T11:49:05Z
2020-06-12
2020-06-14T03:26:44Z
Article - Refereed
BMC Geriatrics. 2020 Jun 12;20(1):205
http://hdl.handle.net/10919/98850
https://doi.org/10.1186/s12877-020-01605-9
en
http://creativecommons.org/licenses/by/4.0/
The Author(s)
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1178912024-03-12T15:59:28Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_23274col_10919_70873col_10919_24292col_10919_23275
Trunk postural control during unstable sitting among individuals with and without low back pain: A systematic review with an individual participant data meta-analysis
Alshehri, Mansour A.
Alzahrani, Hosam
van den Hoorn, Wolbert
Klyne, David M.
Vette, Albert H.
Hendershot, Brad D.
Roberts, Brad W. R.
Larivière, Christian
Barbado, David
Vera-Garcia, Francisco J.
van Dieen, Jaap H.
Cholewicki, Jacek
Nussbaum, Maury A.
Madigan, Michael L.
Reeves, Norman Peter
Silfies, Sheri P.
Brown, Stephen H. M.
Hodges, Paul W.
Introduction Sitting on an unstable surface is a common paradigm to investigate trunk postural control among individuals with low back pain (LBP), by minimizing the influence lower extremities on balance control. Outcomes of many small studies are inconsistent (e.g., some find differences between groups while others do not), potentially due to confounding factors such as age, sex, body mass index [BMI], or clinical presentations. We conducted a systematic review with an individual participant data (IPD) meta-analysis to investigate whether trunk postural control differs between those with and without LBP, and whether the difference between groups is impacted by vision and potential confounding factors. Methods We completed this review according to PRISMA-IPD guidelines. The literature was screened (up to 7th September 2023) from five electronic databases: MEDLINE, CINAHL, Embase, Scopus, and Web of Science Core Collection. Outcome measures were extracted that describe unstable seat movements, specifically centre of pressure or seat angle. Our main analyses included: 1) a two-stage IPD meta-analysis to assess the difference between groups and their interaction with age, sex, BMI, and vision on trunk postural control; 2) and a two-stage IPD meta-regression to determine the effects of LBP clinical features (pain intensity, disability, pain catastrophizing, and fear-avoidance beliefs) on trunk postural control. Results Forty studies (1,821 participants) were included for the descriptive analysis and 24 studies (1,050 participants) were included for the IPD analysis. IPD meta-analyses revealed three main findings: (a) trunk postural control was worse (higher root mean square displacement [RMSdispl], range, and long-term diffusion; lower mean power frequency) among individuals with than without LBP; (b) trunk postural control deteriorated more (higher RMSdispl, shortand long-term diffusion) among individuals with than without LBP when vision was removed; and (c) older age and higher BMI had greater adverse impacts on trunk postural control (higher short-term diffusion; longer time and distance coordinates of the critical point) among individuals with than without LBP. IPD meta-regressions indicated no associations between the limited LBP clinical features that could be considered and trunk postural control. Conclusion Trunk postural control appears to be inferior among individuals with LBP, which was indicated by increased seat movements and some evidence of trunk stiffening. These findings are likely explained by delayed or less accurate corrective responses.
2024-02-08T14:03:20Z
2024-02-08T14:03:20Z
2024-01-24
Article - Refereed
1932-6203
PONE-D-23-31780 (PII)
https://hdl.handle.net/10919/117891
https://doi.org/10.1371/journal.pone.0296968
19
1 January
Nussbaum, Maury [0000-0002-1887-8431]
Madigan, Michael [0000-0002-4299-3851]
38265999
1932-6203
en
https://www.ncbi.nlm.nih.gov/pubmed/38265999
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Public Library of Science
oai:vtechworks.lib.vt.edu:10919/1066152021-11-12T08:11:52Zcom_10919_8195com_10919_25799com_10919_11363com_10919_5539com_10919_24217col_10919_78882col_10919_23164col_10919_24292
Calculating and Analyzing Angular Head Jerk in Augmented and Virtual Reality: Effect of AR Cue Design on Angular Jerk
Van Dam, Jared
Tanous, Kyle
Werner, Matt
Gabbard, Joseph L.
In this work, we propose a convenient method for evaluating levels of angular jerk in augmented reality (AR) and virtual reality (VR). Jerk is a rarely analyzed metric in usability studies, although it can be measured and calculated easily with most head-worn displays and can yield highly relevant information to designers. Here, we developed and implemented a system capable of calculating and analyzing jerk in real-time based on orientation data from an off-the-shelf head-worn display. An experiment was then carried out to determine whether the presence of AR user interface annotations results in changes to users’ angular head jerk when conducting a time-pressured visual search task. Analysis of the data indicates that a decrease in jerk is significantly associated with the use of AR augmentations. As noted in the limitations section, however, the conclusions drawn from this work should be limited, as this analysis method is novel in the VR/AR space and because of methodological limitations that limited the reliability of the jerk data. The work presented herein considerably facilitates the use of jerk as a quick component measure of usability and serves as an initial point off which future research involving jerk in VR and AR can be performed.
2021-11-11T19:25:06Z
2021-11-11T19:25:06Z
2021-10-28
2021-11-11T14:57:24Z
Article - Refereed
Van Dam, J.; Tanous, K.; Werner, M.; Gabbard, J.L. Calculating and Analyzing Angular Head Jerk in Augmented and Virtual Reality: Effect of AR Cue Design on Angular Jerk. Appl. Sci. 2021, 11, 10082.
http://hdl.handle.net/10919/106615
https://doi.org/10.3390/app112110082
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/1171762023-12-11T22:02:36Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539com_10919_23261col_10919_18629col_10919_24292col_10919_23262
Generating synthetic as-built additive manufacturing surface topography using progressive growing generative adversarial networks
Seo, Junhyeon
Rao, Prahalada
Raeymaekers, Bart
additive manufacturing
surface topography
synthetic surface topography
generative adversarial networks
Numerically generating synthetic surface topography that closely resembles the features and characteristics of experimental surface topography measurements reduces the need to perform these intricate and costly measurements. However, existing algorithms to numerically generated surface topography are not well-suited to create the specific characteristics and geometric features of as-built surfaces that result from laser powder bed fusion (LPBF), such as partially melted metal particles, porosity, laser scan lines, and balling. Thus, we present a method to generate synthetic as-built LPBF surface topography maps using a progressively growing generative adversarial network. We qualitatively and quantitatively demonstrate good agreement between synthetic and experimental as-built LPBF surface topography maps using areal and deterministic surface topography parameters, radially averaged power spectral density, and material ratio curves. The ability to accurately generate synthetic as-built LPBF surface topography maps reduces the experimental burden of performing a large number of surface topography measurements. Furthermore, it facilitates combining experimental measurements with synthetic surface topography maps to create large data-sets that facilitate, e.g. relating as-built surface topography to LPBF process parameters, or implementing digital surface twins to monitor complex end-use LPBF parts, amongst other applications.
2023-12-11T13:22:01Z
2023-12-11T13:22:01Z
2023-12-04
2023-12-10T04:07:19Z
Article - Refereed
https://hdl.handle.net/10919/117176
https://doi.org/10.1007/s40544-023-0826-7
en
http://creativecommons.org/licenses/by/4.0/
The author(s)
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1054062023-11-29T00:21:52Zcom_10919_83968com_10919_23759com_10919_24217com_10919_5539col_10919_83969col_10919_24292
Consistency of Sedentary Behavior Patterns among Office Workers with Long-Term Access to Sit-Stand Workstations
Huysmans, Maaike A.
Srinivasan, Divya
Mathiassen, Svend Erik
computer work
day-to-day variability
individual differences
sitting time
temporal patterns
variance component analysis
Introduction: Sit-stand workstations are a popular intervention to reduce sedentary behavior (SB) in office settings. However, the extent and distribution of SB in office workers long-term accustomed to using sit-stand workstations as a natural part of their work environment are largely unknown. In the present study, we aimed to describe patterns of SB in office workers with long-term access to sit-stand workstations and to determine the extent to which these patterns vary between days and workers.
Methods: SB was objectively monitored using thigh-worn accelerometers for a full week in 24 office workers who had been equipped with a sit-stand workstation for at least 10 months. A comprehensive set of variables describing SB was calculated for each workday and worker, and distributions of these variables between days and workers were examined.
Results: On average, workers spent 68% work time sitting [standard deviation (SD) between workers and between days (within worker): 10.4 and 18.2%]; workers changed from sitting to standing/ walking 3.2 times per hour (SDs 0.6 and 1.2 h−1); with bouts of sitting being 14.9 min long (SDs 4.2 and 8.5 min). About one-third of the workers spent >75% of their workday sitting. Between-workers variability was significantly different from zero only for percent work time sitting, while betweendays (within-worker) variability was substantial for all SB variables.
Conclusions: Office workers accustomed to using sit-stand workstations showed homogeneous patterns of SB when averaged across several days, except for percent work time seated. However, SB differed substantially between days for any individual worker. The finding that many workers were extensively sedentary suggests that just access to sit-stand workstations may not be a sufficient remedy against SB; additional personalized interventions reinforcing use may be needed. To this end, differences in SB between days should be acknowledged as a potentially valuable source of variation.
2021-10-18T16:04:21Z
2021-10-18T16:04:21Z
2019-04-22
Article - Refereed
http://hdl.handle.net/10919/105406
https://doi.org/10.1093/annweh/wxz022
63
5
en
http://creativecommons.org/licenses/by-nc/4.0/
Attribution-NonCommercial 4.0 International
Oxford University Press
oai:vtechworks.lib.vt.edu:10919/1136992023-02-08T08:12:43Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Gaussian Process with Input Location Error and Applications to the Composite Parts Assembly Process
Wang, Wenjia
Yue, Xiaowei
Haaland, Benjamin
Wu, C. F. Jeff
This paper investigates Gaussian process modeling with input location error, where the inputs are corrupted by noise. Here, the best linear unbiased predictor for two cases is considered, according to whether there is noise at the target location or not. We show that the mean squared prediction error converges to a nonzero constant if there is noise at the target location, and we provide an upper bound of the mean squared prediction error if there is no noise at the target location. We investigate the use of stochastic Kriging in the prediction of Gaussian processes with input location error and show that stochastic Kriging is a good approximation when the sample size is large. Several numerical examples are given to illustrate the results, and a case study on the assembly of composite parts is presented. Technical proofs are provided in the appendices.
2023-02-07T17:27:35Z
2023-02-07T17:27:35Z
2022-06
2023-02-05T18:06:10Z
Article - Refereed
http://hdl.handle.net/10919/113699
https://doi.org/10.1137/20M1312447
10
2
Yue, Xiaowei [0000-0001-6019-0940]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/962012021-06-21T19:23:11Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78797col_10919_24292
Planning of Cascade Hydropower Stations with the Consideration of Long-Term Operations under Uncertainties
Wang, Changjun
Chen, Shutong
Industrial and Systems Engineering
In the location-related planning of a hydropower system, the consideration of future operations under uncertainties can make the decisions sustainable and robust. Then, it is of great importance to develop an effective approach that deals with the long-term stochasticity due to the long-lasting effects of the location selections. Thus, we propose a multistage stochastic programming model to optimize the planning decisions of cascade hydropower stations and the long-term stochastic operations in an integrated way. The first stage (i.e., the planning stage) in the model deals with the location and capacity decisions of the hydropower stations, while the subsequent stages implement the scheduling decisions under each stagewise stochastic scenario. To address the curse of dimensionality caused by the long-term stochastic operations, we further propose a novel dimensionality reduction approach based on dual equilibrium to transform the multistage model into a tractable two-stage stochastic program. The applicability of our approach is validated by a case study based on a basin of Yangtze River, China, and corresponding sensitivity analysis.
2019-12-23T13:30:11Z
2019-12-23T13:30:11Z
2019-11-28
2019-12-23T13:25:36Z
Article - Refereed
Changjun Wang and Shutong Chen, “Planning of Cascade Hydropower Stations with the Consideration of Long-Term Operations under Uncertainties,” Complexity, vol. 2019, Article ID 1534598, 23 pages, 2019. doi:10.1155/2019/1534598
http://hdl.handle.net/10919/96201
https://doi.org/10.1155/2019/1534598
en
http://creativecommons.org/licenses/by/4.0/
Copyright © 2019 Changjun Wang and Shutong Chen. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Creative Commons Attribution 4.0 International
Hindawi
oai:vtechworks.lib.vt.edu:10919/1181122024-02-22T17:03:12Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Data-driven Car Drag Coefficient Prediction with Depth and Normal Renderings
Song, Binyang
Yuan, Chenyang
Permenter, Frank
Arechiga, Nikos
Ahmed, Faez
Generative AI models have made significant progress in automating the creation of 3D shapes, which has the potential to transform car design. In engineering design and optimization, evaluating engineering metrics is crucial. To make generative models performance-aware and enable them to create high-performing designs, surrogate modeling of these metrics is necessary. However, the currently used representations of 3D shapes either require extensive computational resources to learn or suffer from significant information loss, which impairs their effectiveness in surrogate modeling. To address this issue, we propose a new 2D representation of 3D shapes. We develop a surrogate drag model based on this representation to verify its effectiveness in predicting 3D car drag. We construct a diverse dataset of 4,535 high-quality 3D car meshes labeled by drag coefficients computed from computational fluid dynamics simulations to train our model. Our experiments demonstrate that our model can accurately and efficiently evaluate drag coefficients with an R^2 value above 0.84 for various car categories. Our model is implemented using deep neural networks, making it compatible with recent AI image generation tools (such as Stable Diffusion) and a significant step towards the automatic generation of drag-optimized car designs. Moreover, we demonstrate a case study using the proposed surrogate model to guide a diffusion-based deep generative model for drag-optimized car body synthesis. We have made the dataset and code publicly available at https://decode.mit.edu/projects/dragprediction.
2024-02-22T18:45:04Z
2024-02-22T18:45:04Z
2024
Article - Refereed
1050-0472
https://hdl.handle.net/10919/118112
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
American Society of Mechanical Engineers
oai:vtechworks.lib.vt.edu:10919/1181112024-02-22T17:03:14Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Generative Design for Manufacturing: Integrating Generation with Optimization Using a Guided Voxel Diffusion Model
Song, Binyang
Chilukuri, Premith Kumar
Kang, Sungku
Jin, Ran
In digital manufacturing, converting advanced designs into quality products is hampered by manufacturers' limited design knowledge, restricting the adoption and enhancement of innovative solutions. This paper addresses this challenge through a novel generative denoising diffusion model (DDM) trained on historical 3D design data, enabling the creation of voxel-based designs that meet manufacturing standards. By integrating a surrogate model for evaluating the manufacturability of generated designs, the proposed DDM is able to optimize manufacturability during the generative process. This paper takes a leap forward from the predominant 2D focus of existing generative models towards 3D generative design, which not only broadens manufacturers' design capabilities but also accelerates the development of practical and optimized products. We demonstrate the efficacy of this approach via a case study on Microbial Fuel Cell (MFC) anode design, illustrating how this method can significantly enhance manufacturing workflows and outcomes. Our research offers a path for manufacturers to deepen their design expertise and foster innovation in digital manufacturing.
2024-02-22T18:31:43Z
2024-02-22T18:31:43Z
2024
Conference proceeding
https://hdl.handle.net/10919/118111
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1120702022-10-05T07:13:13Zcom_10919_24217com_10919_5539col_10919_24292
Modeling the impact of traffic management strategies on households' stated evacuation decisions
Bian, Ruijie
Murray-Tuite, Pamela
Edara, Praveen
Triantis, Konstantinos
Hurricane evacuation
Traffic management
Stated evacuation decisions
Contraflow
Evacuation traffic management has been implemented in large-scale disaster evacuations (such as hurricanes) to facilitate traffic flow and reduce travel delay. The outcomes of these strategies were quantified via traffic simulation but were assumed to have no/limited impacts on households' evacuation-related decisions. This study analyzed and modeled the impact of these strategies on five evacuation related household choices (evacuate/stay, departure time, route, vehicle, and destination) separately based on 415 responses collected from a stated preference survey. The survey was conducted in 2017 in coastal areas near Hampton Roads. Traffic management is likely to motivate some (32%) households to evacuate instead of sheltering in place. In addition, not all households take the interstates with traffic management even though route choice is the most likely to be affected by traffic management. Households need more information for their departure time and destination choices in response to traffic management since they are more likely to feel uncertain of the impact of the strategies on these decisions. Such uncertainty in departure time and destination choice is especially true for those who evacuate late and for those who choose accommodations other than the home of friends/relatives. Emergency management agencies should also be aware that some households may intentionally depart before traffic management starts. Among the five choices, vehicle use is the choice that is least likely to be affected. All the above-mentioned findings potentially affect parameter specifications in evacuation traffic simulation studies. This study then used multinomial logit models to estimate the impacts of traffic management on each of the five evacuation related choices. The model estimation results can help improve evacuation demand predictions and guide evacuation information dissemination.
2022-10-04T16:46:23Z
2022-10-04T16:46:23Z
2022-10
Article - Refereed
2590-0617
100246
http://hdl.handle.net/10919/112070
https://doi.org/10.1016/j.pdisas.2022.100246
15
en
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Elsevier
oai:vtechworks.lib.vt.edu:10919/887712021-10-08T16:43:38Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_78882col_10919_24292
Constructing True Model-Based Requirements in SysML
Salado Diez, Alejandro
Wach, Paul
Industrial and Systems Engineering
requirements
model-based requirements
model-based systems engineering (MBSE)
System Modeling Language (SysML)
Some authors suggest that transitioning requirements engineering from the traditional statements in natural language with shall clauses to model-based requirements within a Model-Based Systems Engineering (MBSE) environment could improve communication, requirements traceability, and system decomposition, among others. Requirement elements in the Systems Modeling Language (SysML) fail to fulfill this objective, as they are really a textual requirement in natural language as a model element. Current efforts to directly leverage behavioral and structural models of the system lack an overarching theoretical framework with which to assess the adequacy of how those models are used to capture requirements. This paper presents an approach to construct true model-based requirements in SysML. The presented approach leverages some of SysML’s behavioral and structural models and diagrams, with specific construction rules derived from Wymore’s mathematical framework for MBSE and taxonomies of requirements and interfaces. The central proposition of the approach is that every requirement can be modeled as an input/output transformation. Examples are used to show how attributes traditionally thought of as non-functional requirements can be captured, with higher precision, as functional transformations.
2019-04-01T12:01:24Z
2019-04-01T12:01:24Z
2019-03-28
2019-03-29T19:41:10Z
Article - Refereed
Salado, A.; Wach, P. Constructing True Model-Based Requirements in SysML. Systems 2019, 7, 19.
http://hdl.handle.net/10919/88771
https://doi.org/10.3390/systems7020019
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
MDPI
oai:vtechworks.lib.vt.edu:10919/889502023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
The immune epitope database (IEDB) 3.0
Vita, Randi
Overton, James A.
Greenbaum, Jason A.
Ponomarenko, Julia
Clark, Jason D.
Cantrell, Jason R.
Wheeler, Daniel K.
Gabbard, Joseph L.
Hix, Deborah
Sette, Alessandro
Peters, Bjoern
Industrial and Systems Engineering
resources
ontology
genbank
The IEDB, www.iedb.org, contains information on immune epitopes-the molecular targets of adaptive immune responses-curated from the published literature and submitted by National Institutes of Health funded epitope discovery efforts. From 2004 to 2012 the IEDB curation of journal articles published since 1960 has caught up to the present day, with > 95% of relevant published literature manually curated amounting to more than 15 000 journal articles and more than 704 000 experiments to date. The revised curation target since 2012 has been to make recent research findings quickly available in the IEDB and thereby ensure that it continues to be an up-to-date resource. Having gathered a comprehensive dataset in the IEDB, a complete redesign of the query and reporting interface has been performed in the IEDB 3.0 release to improve how end users can access this information in an intuitive and biologically accurate manner. We here present this most recent release of the IEDB and describe the user testing procedures as well as the use of external ontologies that have enabled it.
2019-04-12T14:55:18Z
2019-04-12T14:55:18Z
2015-01-28
Article - Refereed
0305-1048
http://hdl.handle.net/10919/88950
https://doi.org/10.1093/nar/gku938
43
D1
25300482
1362-4962
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1135592023-02-01T08:15:51Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Effect of mandating vaccination on COVID-19 cases in colleges and universities
Ghaffarzadegan, Navid
COVID-19
colleges
higher education
mandate
universities
vaccine
Vaccine Related
Prevention
Immunization
3.4 Vaccines
3 Prevention of disease and conditions, and promotion of well-being
4 Quality Education
Background: With the introduction of COVID-19 vaccines, many colleges and universities decided to mandate vaccination for all students and employees. The objective of this paper is to empirically investigate the effect of the mandate policy on Fall 2021 COVID-19 cases in institutions of higher education. Method: We construct a unique dataset of a sample of 94 colleges and universities in the east and southeast regions of the United States, 41 of which required vaccination prior to Fall 2021. A difference-in-differences analysis is conducted, considering vaccine requirement as a policy implemented only in a sub-group of these institutions. We control for several factors, including state-level case per capita and student population. Results: Our analysis shows that mandatory vaccination substantially decreased cases in institutions of higher education by 1,473 cases per 100,000 student population (95 CI: 132, 2813). Conclusions: The results suggest that a COVID-19 vaccine requirement is an effective policy in decreasing cases in such institutions, leading to a safer educational experience.
2023-01-30T17:56:27Z
2023-01-30T17:56:27Z
2022-10-01
2023-01-28T15:45:22Z
Article - Refereed
1201-9712
S1201-9712(22)00477-5 (PII)
http://hdl.handle.net/10919/113559
https://doi.org/10.1016/j.ijid.2022.08.004
123
Ghaffarzadegan, Navid [0000-0003-3632-8588]
35985570
1878-3511
en
https://www.ncbi.nlm.nih.gov/pubmed/35985570
http://creativecommons.org/licenses/by-nc-nd/4.0/
Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International
Elsevier
oai:vtechworks.lib.vt.edu:10919/1136982023-02-08T08:12:42Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539com_10919_24369col_10919_70873col_10919_24292col_10919_24370
Partitioned Active Learning for Heterogeneous Systems
Lee, Cheolhei
Wang, Kaiwen
Wu, Jianguo
Cai, Wenjun
Yue, Xiaowei
Active learning is a subfield of machine learning that focuses on improving the data collection efficiency in expensive-to-evaluate systems. Active learning-applied surrogate modeling facilitates cost-efficient analysis of demanding engineering systems, while the existence of heterogeneity in underlying systems may adversely affect the performance. In this article, we propose the partitioned active learning that quantifies informativeness of new design points by circumventing heterogeneity in systems. The proposed method partitions the design space based on heterogeneous features and searches for the next design point with two systematic steps. The global searching scheme accelerates exploration by identifying the most uncertain subregion, and the local searching utilizes circumscribed information induced by the local Gaussian process (GP). We also propose Cholesky update-driven numerical remedies for our active learning to address the computational complexity challenge. The proposed method consistently outperforms existing active learning methods in three real-world cases with better prediction and computation time.
2023-02-07T17:16:39Z
2023-02-07T17:16:39Z
2023-08
2023-02-05T04:01:23Z
Article - Refereed
http://hdl.handle.net/10919/113698
Yue, Xiaowei [0000-0001-6019-0940]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
ASME
oai:vtechworks.lib.vt.edu:10919/1125872022-11-15T08:13:47Zcom_10919_24217com_10919_5539col_10919_24292
In-process monitoring and prediction of droplet quality in droplet-on-demand liquid metal jetting additive manufacturing using machine learning
Gaikwad, Aniruddha
Chang, Tammy
Giera, Brian
Watkins, Nicholas
Mukherjee, Saptarshi
Pascall, Andrew
Stobbe, David
Rao, Prahalada
Droplet-on-demand liquid metal jetting (DoD-LMJ)
In-process sensing and monitoring
High-speed imaging
Millimeter-wave sensing
Machine learning
In droplet-on-demand liquid metal jetting (DoD-LMJ) additive manufacturing, complex physical interactions govern the droplet characteristics, such as size, velocity, and shape. These droplet characteristics, in turn, determine the functional quality of the printed parts. Hence, to ensure repeatable and reliable part quality it is necessary to monitor and control the droplet characteristics. Existing approaches for in-situ monitoring of droplet behavior in DoD-LMJ rely on high-speed imaging sensors. The resulting high volume of droplet images acquired is computationally demanding to analyze and hinders real-time control of the process. To overcome this challenge, the objective of this work is to use time series data acquired from an in-process millimeter-wave sensor for predicting the size, velocity, and shape characteristics of droplets in DoD-LMJ process. As opposed to high-speed imaging, this sensor produces data-efficient time series signatures that allows rapid, real-time process monitoring. We devise machine learning models that use the millimeter-wave sensor data to predict the droplet characteristics. Specifically, we developed multilayer perceptron-based non-linear autoregressive models to predict the size and velocity of droplets. Likewise, a supervised machine learning model was trained to classify the droplet shape using the frequency spectrum information contained in the millimeter-wave sensor signatures. High-speed imaging data served as ground truth for model training and validation. These models captured the droplet characteristics with a statistical fidelity exceeding 90%, and vastly outperformed conventional statistical modeling approaches. Thus, this work achieves a practically viable sensing approach for real-time quality monitoring of the DoD-LMJ process, in lieu of the existing data-intensive image-based techniques.
2022-11-14T17:59:11Z
2022-11-14T17:59:11Z
2022-10
Article - Refereed
0956-5515
http://hdl.handle.net/10919/112587
https://doi.org/10.1007/s10845-022-01977-2
33
7
1572-8145
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Springer
oai:vtechworks.lib.vt.edu:10919/1165882023-11-06T19:39:34Zcom_10919_8195com_10919_25799com_10919_24217com_10919_5539col_10919_105038col_10919_24292
Ensemble Active Learning by Contextual Bandits for AI Incubation in Manufacturing
Zeng, Yingyan
Chen, Xiaoyu
Jin, Ran
An Industrial Cyber-physical System (ICPS) provide a digital foundation for data-driven decision-making by artificial intelligence (AI) models. However, the poor data quality (e.g., inconsistent distribution, imbalanced classes) of high-speed, large-volume data streams poses significant challenges to the online deployment of offline-trained AI models. As an alternative, updating AI models online based on streaming data enables continuous improvement and resilient modeling performance. However, for a supervised learning model (i.e., a base learner), it is labor-intensive to annotate all streaming samples to update the model. Hence, a data acquisition method is needed to select the data for annotation to ensure data quality while saving annotation efforts. In the literature, active learning methods have been proposed to acquire informative samples. Different acquisition criteria were developed for exploration of under-represented regions in the input variable space or exploitation of the well-represented regions for optimal estimation of base learners. However, it remains a challenge to balance the exploration-exploitation trade-off under different online annotation scenarios. On the other hand, an acquisition criterion learned by AI adapts itself to a scenario dynamically, but the ambiguous consideration of the trade-off limits its performance in frequently changing manufacturing contexts. To overcome these limitations, we propose an ensemble active learning method by contextual bandits (CbeAL). CbeAL incorporates a set of active learning agents (i.e., acquisition criteria) explicitly designed for exploration or exploitation by a weighted combination of their acquisition decisions. The weight of each agent will be dynamically adjusted based on the usefulness of its decisions to improve the performance of the base learner. With adaptive and explicit consideration of both objectives, CbeAL efficiently guides the data acquisition process by selecting informative samples to reduce the human annotation efforts. Furthermore, we characterize the exploration and exploitation capability of the proposed agents theoretically. The evaluation results in a numerical simulation study and a real case study demonstrate the effectiveness and efficiency of CbeAL in manufacturing process modeling of the ICPS.
2023-11-02T13:02:51Z
2023-11-02T13:02:51Z
2023-10
2023-11-01T08:00:35Z
Article - Refereed
http://hdl.handle.net/10919/116588
https://doi.org/10.1145/3627821
en
http://rightsstatements.org/vocab/InC/1.0/
The author(s)
In Copyright
ACM
oai:vtechworks.lib.vt.edu:10919/1043972023-11-29T15:22:53Zcom_10919_78629com_10919_78628com_10919_111405com_10919_110083com_10919_24217com_10919_5539col_10919_79979col_10919_111406col_10919_24292
Cyberphysical Security Through Resiliency: A Systems-Centric Approach
Fleming, Cody H.
Elks, Carl R.
Bakirtzis, Georgios
Adams, Stephen C.
Carter, Bryan
Beling, Peter A.
Horowitz, Barry M.
Industrial and Systems Engineering
Hume Center for National Security and Technology
Cyberphysical systems require resiliency techniques for defense, and multicriteria resiliency problems need an approach that evaluates systems for current threats and potential design solutions. A systems-oriented view of cyberphysical security, termed Mission Aware, is proposed based on a holistic understanding of mission goals, system dynamics, and risk.
2021-07-26T13:38:11Z
2021-07-26T13:38:11Z
2021-06
Article - Refereed
0018-9162
http://hdl.handle.net/10919/104397
https://doi.org/10.1109/MC.2020.3039491
54
6
1558-0814
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/819532023-07-12T17:57:37Zcom_10919_24217com_10919_5539com_10919_79468com_10919_78628col_10919_24292col_10919_79480
Recent trends in the U.S. Behavioral and
Social Sciences Research (BSSR) workforce
Hur, Hyungjo
Andalib, Maryam A.
Maurer, Julie A.
Hawley, Joshua D.
Ghaffarzadegan, Navid
Industrial and Systems Engineering
While behavioral and social sciences occupations comprise one of the largest portions of the "STEM" workforce, most studies of diversity in STEM overlook this population, focusing instead on fields such as biomedical or physical sciences. This study evaluates major demographic trends and productivity in the behavioral and social sciences research (BSSR) workforce in the United States during the past decade. Our analysis shows that the demographic trends for different BSSR fields vary. In terms of gender balance, there is no single trend across all BSSR fields; rather, the problems are field-specific, and disciplines such as economics and political science continue to have more men than women. We also show that all BSSR fields suffer from a lack of racial and ethnic diversity. The BSSR workforce is, in fact, less representative of racial and ethnic minorities than are biomedical sciences or engineering. Moreover, in many BSSR subfields, minorities are less likely to receive funding. We point to various funding distribution patterns across different demographic groups of BSSR scientists, and discuss several policy implications.
2018-01-29T15:30:06Z
2018-01-29T15:30:06Z
2017-02-06
Article - Refereed
http://hdl.handle.net/10919/81953
https://doi.org/10.1371/journal.pone.0170887
12
2
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
PLOS
oai:vtechworks.lib.vt.edu:10919/1141452023-03-23T07:29:35Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
A pilot study investigating motor adaptations when learning to walk with a whole-body powered exoskeleton
Park, Hanjun
Kim, Sunwook
Nussbaum, Maury A.
Srinivasan, Divya
EMG
Gait performance
Human-robot interaction
Motor learning
Rehabilitation
Physical rehabilitation
Clinical research
Musculoskeletal
Evidence is emerging on how whole-body powered exoskeleton (EXO) use impacts users in basic occupational work scenarios, yet our understanding of how users learn to use this complex technology is limited. We explored how novice users adapted to using an EXO during gait. Six novices and five experienced users completed the study. Novices completed an initial training/familiarization gait session, followed by three subsequent gait sessions using the EXO, while experienced users completed one gait session with the EXO. Spatiotemporal gait measures, pelvis and lower limb joint kinematics, muscle activities, EXO torques, and human-EXO interaction forces were measured. Adaptations among novices were most pronounced in spatiotemporal gait measures, followed by joint kinematics, with smaller changes evident in muscle activity and EXO joint torques. Compared to the experienced users, novices exhibited a shorter step length and walked with significantly greater anterior pelvic tilt and less hip extension. Novices also used lower joint torques from the EXO at the hip and knee, and they had greater biceps femoris activity. Overall, our results may suggest that novices exhibited clear progress in learning, but they had not yet adopted motor strategies similar to those of experienced users after the three sessions. We suggest potential future directions to enhance motor adaptations to powered EXO in terms of both training protocols and human-EXO interfaces.
2023-03-22T15:14:05Z
2023-03-22T15:14:05Z
2023-04-01
2023-03-22T11:58:27Z
Article - Refereed
1050-6411
S1050-6411(23)00014-7 (PII)
http://hdl.handle.net/10919/114145
https://doi.org/10.1016/j.jelekin.2023.102755
69
Nussbaum, Maury [0000-0002-1887-8431]
36921425
1873-5711
en
https://www.ncbi.nlm.nih.gov/pubmed/36921425
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Elsevier
oai:vtechworks.lib.vt.edu:10919/1098142022-05-06T07:11:45Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Exploratory field testing of passive exoskeletons in several manufacturing environments: perceived usability and user acceptance
Schwerha, Diana
McNamara, Nathan
Kim, Sun Wook
Nussbaum, Maury A.
Assistive device
field study
intervention
technology adoption
work-related musculoskeletal disorders
OCCUPATIONAL APPLICATIONS: Results of the current exploratory study suggest that use of an exoskeleton (EXO) has the potential to be accepted by workers as an intervention in diverse manufacturing environments. Also evident were that the major factors contributing to EXO-use-intention are perceived comfort, task-technology fit, perceived safety, and perceived usefulness. A user's perception of perceived usability may be established by using an exoskeleton during actual job tasks, yet some aspects of perceived usability likely require multiple exposures to an EXO for an accurate assessment. Many negative comments regarding EXO use were related to physical constraints (e.g., restricted movements, bulkiness), and to the EXO interface (e.g., straps, cuff designs), suggesting a need for further research on EXO design to minimize discomfort. In practice, there is likely value in having workers use and explore candidate EXOs during their actual job, both to accurately assess the usefulness of an EXO and to find the most effective EXO.
2022-05-05T17:50:37Z
2022-05-05T17:50:37Z
2022-04-22
2022-05-05T16:20:22Z
Article - Refereed
2472-5838
10.1080/24725838.2022.2059594 (PII)
http://hdl.handle.net/10919/109814
Kim, Sun Wook [0000-0003-3624-1781]
Nussbaum, Maury [0000-0002-1887-8431]
35354354
2472-5846
en
https://www.ncbi.nlm.nih.gov/pubmed/35354354
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/522712023-07-12T17:57:37Zcom_10919_24217com_10919_5539col_10919_24292
The effect of burst duration, interstimulus onset interval, and loudspeaker arrangement on auditory apparent motion in the free field
Strybel, Thomas Z.
Neale, Wayne
Industrial and Systems Engineering
Binaural hearing
Acoustic signal processing
Acoustical measurements
Loudspeakers
The illusion of auditory apparent motion (AAM) was examined in order to determine the burst durations and interstimulus onset intervals (ISOIs) at which AAM is heard when spatial information regarding source location was varied. In the first experiment AAM was examined in the free field under monaural and binaural listening conditions. AAM was heard at the same burst duration-ISOI combinations for both listening conditions, but the location of the lead source could be determined only under binaural listening. In the second experiment AAM was measured with two and three sound sources. The number of sources did not affect the burst duration-ISOI combinations that produced AAM, but did affect the determination of the location of the lead source. In the third experiment AAM was tested when the sources were located in the median plane. The sources were located either at 0 degrees and 180 degrees azimuth, or both at 0 degrees azimuth, one in the horizontal plane and one 20 degrees above. The location of the speakers did not affect the timing requirements for the perception of AAM, only the timing requirements for the detection of the lead source. In the fourth experiment, AAM was measured when the vertical separation between the sources was either 2.5 degrees or 20 degrees. AAM was heard at both separations, even though 2.5 degrees is less than the vertical MAA. In each of these experiments only burst duration and ISOI determined whether motion was heard. Localization cues were important only for the determination of the direction of motion. Copyright 1994 Acoustical Society of America
2015-05-13T22:30:07Z
2015-05-13T22:30:07Z
1994-12-01
2015-05-12
Article - Refereed
Strybel, T. Z., & Neale, W. (1994). The effect of burst duration, interstimulus onset interval, and loudspeaker arrangement on auditory apparent motion in the free field. Journal of the Acoustical Society of America, 96(6), 3463-3475. doi: 10.1121/1.411452
0001-4966
http://hdl.handle.net/10919/52271
http://scitation.aip.org/content/asa/journal/jasa/96/6/10.1121/1.411452
https://doi.org/10.1121/1.411452
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
Acoustical Society of America
oai:vtechworks.lib.vt.edu:10919/889542023-11-29T11:26:33Zcom_10919_25796com_10919_24217com_10919_5539col_10919_25797col_10919_24292
PATRIC, the bacterial bioinformatics database and analysis resource
Wattam, Alice R.
Abraham, David
Dalay, Oral
Disz, Terry L.
Driscoll, Timothy
Gabbard, Joseph L.
Gillespie, Joseph J.
Gough, Roger
Hix, Deborah
Kenyon, Ronald W.
Machi, Dustin
Mao, Chunhong
Nordberg, Eric K.
Olson, Robert
Overbeek, Ross
Pusch, Gordon D.
Shukla, Maulik
Schulman, Julie
Stevens, Rick L.
Sullivan, Daniel E.
Vonstein, Veronika
Warren, Andrew S.
Will, Rebecca
Wilson, Meredith J. C.
Yoo, Hyunseung
Zhang, Chengdong
Zhang, Yan
Sobral, Bruno
Fralin Life Sciences Institute
Industrial and Systems Engineering
molecular interaction database
antibiotic-resistance genes
infectious-diseases
structural genomics
pathogen database
virulence factors
data sets
update
integration
tools
The Pathosystems Resource Integration Center (PATRIC) is the all-bacterial Bioinformatics Resource Center (BRC) (http://www.patricbrc.org). A joint effort by two of the original National Institute of Allergy and Infectious Diseases-funded BRCs, PATRIC provides researchers with an online resource that stores and integrates a variety of data types [e. g. genomics, transcriptomics, protein-protein interactions (PPIs), three-dimensional protein structures and sequence typing data] and associated metadata. Datatypes are summarized for individual genomes and across taxonomic levels. All genomes in PATRIC, currently more than 10 000, are consistently annotated using RAST, the Rapid Annotations using Subsystems Technology. Summaries of different data types are also provided for individual genes, where comparisons of different annotations are available, and also include available transcriptomic data. PATRIC provides a variety of ways for researchers to find data of interest and a private workspace where they can store both genomic and gene associations, and their own private data. Both private and public data can be analyzed together using a suite of tools to perform comparative genomic or transcriptomic analysis. PATRIC also includes integrated information related to disease and PPIs. All the data and integrated analysis and visualization tools are freely available. This manuscript describes updates to the PATRIC since its initial report in the 2007 NAR Database Issue.
2019-04-12T14:55:19Z
2019-04-12T14:55:19Z
2014-01
Article - Refereed
0305-1048
http://hdl.handle.net/10919/88954
https://doi.org/10.1093/nar/gkt1099
42
D1
24225323
1362-4962
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/1164302023-10-10T07:14:18Zcom_10919_24215com_10919_5539com_10919_24217col_10919_24289col_10919_24292
Comparing Self-Report Assessments and Scenario-Based Assessments of Systems Thinking Competence
Davis, Kirsten A.
Grote, Dustin
Mahmoudi, Hesam
Perry, Logan
Ghaffarzadegan, Navid
Grohs, Jacob
Hosseinichimeh, Niyousha
Knight, David B.
Triantis, Konstantinos
Self-report assessments
Scenario-based assessment
Systems thinking
Competence assessment
Self-report assessments are used frequently in higher education to assess a variety of constructs, including attitudes, opinions, knowledge, and competence. Systems thinking is an example of one competence often measured using self-report assessments where individuals answer several questions about their perceptions of their own skills, habits, or daily decisions. In this study, we define systems thinking as the ability to see the world as a complex interconnected system where different parts can influence each other, and the interrelationships determine system outcomes. An alternative, less-common, assessment approach is to measure skills directly by providing a scenario about an unstructured problem and evaluating respondents' judgment or analysis of the scenario (scenario-based assessment). This study explored the relationships between engineering students' performance on self-report assessments and scenario-based assessments of systems thinking, finding that there were no significant relationships between the two assessment techniques. These results suggest that there may be limitations to using self-report assessments as a method to assess systems thinking and other competencies in educational research and evaluation, which could be addressed by incorporating alternative formats for assessing competence. Future work should explore these findings further and support the development of alternative assessment approaches.
2023-10-09T13:36:20Z
2023-10-09T13:36:20Z
2023-03
Article - Refereed
1059-0145
http://hdl.handle.net/10919/116430
https://doi.org/10.1007/s10956-023-10027-2
1573-1839
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Springer
oai:vtechworks.lib.vt.edu:10919/855092023-04-14T17:49:40Zcom_10919_24217com_10919_5539col_10919_24292
Load-Relaxation Properties of the Human Trunk in Response to Prolonged Flexion: Measuring and Modeling the Effect of Flexion Angle
Toosizadeh, Nima
Nussbaum, Maury A.
Bazrgari, Babak
Madigan, Michael L.
Biomedical Engineering and Mechanics
Industrial and Systems Engineering
School of Biomedical Engineering and Sciences
Experimental studies suggest that prolonged trunk flexion reduces passive support of the spine. To understand alterations of the synergy between active and passive tissues following such loadings, several studies have assessed the time-dependent behavior of passive tissues including those within spinal motion segments and muscles. Yet, there remain limitations regarding load-relaxation of the lumbar spine in response to flexion exposures and the influence of different flexion angles. Ten healthy participants were exposed for 16 min to each of five magnitudes of lumbar flexion specified relative to individual flexion-relaxation angles (i.e., 30, 40, 60, 80, and 100%), during which lumbar flexion angle and trunk moment were recorded. Outcome measures were initial trunk moment, moment drop, parameters of four viscoelastic models (i.e., Standard Linear Solid model, the Prony Series, Schapery's Theory, and the Modified Superposition Method), and changes in neutral zone and viscoelastic state following exposure. There were significant effects of flexion angle on initial moment, moment drop, changes in normalized neutral zone, and some parameters of the Standard Linear Solid model. Initial moment, moment drop, and changes in normalized neutral zone increased exponentially with flexion angle. Kelvin-solid models produced better predictions of temporal behaviors. Observed responses to trunk flexion suggest nonlinearity in viscoelastic properties, and which likely reflected viscoelastic behaviors of spinal (lumbar) motion segments. Flexion-induced changes in viscous properties and neutral zone imply an increase in internal loads and perhaps increased risk of low back disorders. Kelvin-solid models, especially the Prony Series model appeared to be more effective at modeling load-relaxation of the trunk.
2018-10-25T15:28:19Z
2018-10-25T15:28:19Z
2012-11-05
Article - Refereed
e48625
http://hdl.handle.net/10919/85509
https://doi.org/10.1371/journal.pone.0048625
7
11
23144913
1932-6203
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
PLOS
oai:vtechworks.lib.vt.edu:10919/1138812023-02-21T08:11:46Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
Semi-infinite mixed binary and disjunctive programs: Applications to set-covering with infinite demand points and implicit hitting set problems
Bansal, Manish
Sherali and Adams [Discrete Applied Math. 157: 1319-1333, 2009] derived convex hull of semi-infinite mixed binary linear programs (SIMBLPs) using Reformulation-Linearization Technique (RLT). In this paper, we study semi-infinite disjunctive programs (SIDPs – a generalization of SIMBLPs) and present linear programming equivalent and valid inequalities for them. We utilize these results for deriving a hierarchy of relaxations for SIMBLPs along with solution approaches for them. This also establishes a direct connection between RLT and linear programming equivalent for disjunctive programs, even without sequential convexification and the requirement of computing projections multiple times. Additionally, we present an exact algorithm for SIBLPs with implicity defined constraints (SIBLP-IC), and formulate set-covering problem with infinite number of demand points or spatial representation of demand as SIBLP-IC. Based on our computational results for solving the set-covering (and equivalent implicit hitting set) problem instances, we observe that the foregoing approach is computationally efficient in comparison to Gurobi 9.5.2 and an algorithm of Moreno-Centeno and Karp [Operations Research 61(2): 453-468, 2013] for implicit hitting set problem (a special case of SIBLP-IC).
2023-02-20T18:30:50Z
2023-02-20T18:30:50Z
2023-02
2023-02-19T15:06:25Z
Article
http://hdl.handle.net/10919/113881
Bansal, Manish [0000-0002-5617-3862]
en
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/1044382022-02-25T03:17:17Zcom_10919_24217com_10919_5539col_10919_24292
Development of supine and standing knee joint position sense tests
Strong, Andrew
Srinivasan, Divya
Häger, Charlotte K.
Industrial and Systems Engineering
Proprioception
Knee
Athletes
Reliability
Objectives: We aimed to assess the test-retest reliability of a supine and standing knee joint position sense (JPS) test, respectively, and whether they discriminate knees with anterior cruciate ligament (ACL) injury from asymptomatic knees. Design: Repeated measures and cross-sectional. Setting: Research laboratory. Participants: For test-retest reliability, 24 persons with asymptomatic knees. For discriminative analysis: 1) ACLR -18 persons on average 23 months after unilateral ACL reconstruction, 2) CTRL - 23 less-active persons, and 3) ATHL - 21 activity level-matched athletes. Main outcome measures: Absolute error (AE) and variable error (VE). Results: Test-retest reliability was generally highest for AE of the standing test (ICC 0.64-0.91). Errors were less for the standing compared to the supine test across groups. CTRL had greater knee JPS AE (P = 0.005) and VE (P = 0.040) than ACLR. ACLR knees showed greater VE compared to the contralateral non-injured knees for both tests (P = 0.032), albeit with a small effect size (eta(2)(p) = 0.244). Conclusions: Our standing test was more reliable and elicited lesser errors than our supine test. Less-active controls, rather than ACLR, produced significantly greater errors. Activity level may be a more predominant factor than ACLR for knee JPS similar to 2 years post-reconstruction. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).
2021-07-29T12:47:02Z
2021-07-29T12:47:02Z
2021-05
Article - Refereed
1466-853X
http://hdl.handle.net/10919/104438
https://doi.org/10.1016/j.ptsp.2021.02.010
49
33667776
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
oai:vtechworks.lib.vt.edu:10919/843912023-07-12T17:57:38Zcom_10919_5com_10919_25799com_10919_24217com_10919_5539col_10919_70873col_10919_24292
On Distributionally Robust Chance Constrained Program with Wasserstein Distance
Xie, W.
Industrial and Systems Engineering
math.OC
90C15, 90C22, 90C59
This paper studies a distributionally robust chance constrained program (DRCCP) with Wasserstein ambiguity set, where the uncertain constraints should satisfy with a probability at least a given threshold for all the probability distributions of the uncertain parameters within a chosen Wasserstein distance from an empirical distribution. In this work, we investigate equivalent reformulations and approximations of such problems. We first show that a DRCCP can be reformulated as a conditional-value-at-risk constrained optimization problem, and thus admits tight inner and outer approximations. When the metric space of uncertain parameters is a normed vector space, we show that a DRCCP of bounded feasible region is mixed integer representable by introducing big-M coefficients and additional binary variables. For a DRCCP with pure binary decision variables, by exploring submodular structure, we show that it admits a big-M free formulation and can be solved by branch and cut algorithm. This result can be generalized to mixed integer DRCCPs. Finally, we present a numerical study to illustrate effectiveness of the proposed methods.
2018-07-25T20:44:20Z
2018-07-25T20:44:20Z
2018-06-21
Article - Refereed
http://hdl.handle.net/10919/84391
Xie, W [0000-0001-5157-1194]
en
http://arxiv.org/abs/1806.07418v1
http://rightsstatements.org/vocab/InC/1.0/
In Copyright
oai:vtechworks.lib.vt.edu:10919/863442023-11-29T19:10:48Zcom_10919_5540com_10919_24217com_10919_5539com_10919_79468com_10919_78628col_10919_71752col_10919_24292col_10919_79481
A Spectral Fiedler Field-based Contrast Platform for Imaging of Nanoparticles in Colon Tumor
Liu, Chenang
Kapoor, Ankur
VanOsdol, Joshua
Ektate, Kalyani
Kong, Zhenyu
Ranjan, Ashish
Industrial and Systems Engineering
intensity focused ultrasound
liposomal drug-delivery
sensitive liposomes
echogenic liposomes
cancer theranostics
in-vivo
Temperature
therapy
radiotherapy
systems
The temporal and spatial patterns of nanoparticle that ferry both imaging and therapeutic agent in solid tumors is significantly influenced by target tissue movement, low spatial resolution, and inability to accurately define regions of interest (ROI) at certain tissue depths. These combine to limit and define nanoparticle untreated regions in tumors. Utilizing graph and matrix theories, the objective of this project was to develop a novel spectral Fiedler field (SFF) based-computational technology for nanoparticle mapping in tumors. The novelty of SFF lies in the utilization of the changes in the tumor topology from baseline for contrast variation assessment. Data suggest that SFF can enhance the spatiotemporal contrast compared to conventional method by 2-3 folds in tumors. Additionally, the SFF contrast is readily translatable for assessment of tumor drug distribution. Thus, our SFF computational platform has the potential for integration into devices that allow contrast and drug delivery applications.
2018-12-11T17:55:43Z
2018-12-11T17:55:43Z
2018-07-30
Article - Refereed
2045-2322
11390
http://hdl.handle.net/10919/86344
https://doi.org/10.1038/s41598-018-29675-1
8
30061558
en
http://creativecommons.org/licenses/by/4.0/
Creative Commons Attribution 4.0 International
Springer Nature
rdf///col_10919_24292/100