Scholarly Works, Civil and Environmental Engineering

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Can Common Pool Resource Theory Catalyze Stakeholder-Driven Solutions to the Freshwater Salinization Syndrome?
Grant, Stanley B.; Rippy, Megan A.; Birkland, Thomas A.; Schenk, Todd; Rowles, Kristin; Misra, Shalini; Aminpour, Payam; Kaushal, Sujay; Vikesland, Peter J.; Berglund, Emily; Gomez-Velez, Jesus D.; Hotchkiss, Erin R.; Perez, Gabriel; Zhang, Harry X.; Armstrong, Kingston; Bhide, Shantanu V.; Krauss, Lauren; Maas, Carly; Mendoza, Kent; Shipman, Caitlin; Zhang, Yadong; Zhong, Yinman (American Chemical Society, 2022-09-14)
Freshwater salinity is rising across many regions of the United States as well as globally, a phenomenon called the freshwater salinization syndrome (FSS). The FSS mobilizes organic carbon, nutrients, heavy metals, and other contaminants sequestered in soils and freshwater sediments, alters the structures and functions of soils, streams, and riparian ecosystems, threatens drinking water supplies, and undermines progress toward many of the United Nations Sustainable Development Goals. There is an urgent need to leverage the current understanding of salinization's causes and consequences?in partnership with engineers, social scientists, policymakers, and other stakeholders?into locally tailored approaches for balancing our nation's salt budget. In this feature, we propose that the FSS can be understood as a common pool resource problem and explore Nobel Laureate Elinor Ostrom's social-ecological systems framework as an approach for identifying the conditions under which local actors may work collectively to manage the FSS in the absence of top-down regulatory controls. We adopt as a case study rising sodium concentrations in the Occoquan Reservoir, a critical water supply for up to one million residents in Northern Virginia (USA), to illustrate emerging impacts, underlying causes, possible solutions, and critical research needs.
The sanitary sewer unit hydrograph model: A comprehensive tool for wastewater flow modeling and inflow-infiltration simulations
Perez, Gabriel; Gomez-Velez, Jesus D.; Grant, Stanley B. (Elsevier, 2023-12-08)
Sanitary sewer systems are critical urban water infrastructure that protect both human and environmental health. Their design, operation, and monitoring require novel modeling techniques that capture dominant processes while allowing for computationally efficient simulations. Open water flow in sewers and rivers are intrinsically similar processes. With this in mind, we formulated a new parsimonious model inspired by the Width Function Instantaneous Unit Hydrograph (WFIUH) approach, widely used to predict rainfall-runoff relationships in watersheds, to a sanitary sewer system consisting of nearly 10,000 sewer conduits and 120,000 residential and commercial sewage connections in Northern Virginia, U.S.A. Model predictions for the three primary components of sanitary flow, including Base Wastewater Flow (BWF), Groundwater Infiltration (GWI), and Runoff Derived Infiltration and Inflow (RDII), compare favorably with the more computationally demanding industry-standard Storm Water Management Model (SWMM). This novel application of the WFIUH modeling framework should support a number of critical water quality endpoints, including (i) sewer hydrograph separation through the quantification of BWF, GWI, and RDII outflows, (ii) evaluation of the impact of new urban developments on sewage flow dynamics, (iii) monitoring and mitigation of sanitary sewer overflows, and (iv) design and interpretation of wastewater surveillance studies.
The anthropogenic salt cycle
Kaushal, Sujay S.; Likens, Gene E.; Mayer, Paul M.; Shatkay, Ruth R.; Shelton, Sydney A.; Grant, Stanley B.; Utz, Ryan M.; Yaculak, Alexis M.; Maas, Carly M.; Reimer, Jenna E.; Bhide, Shantanu V.; Malin, Joseph T.; Rippy, Megan A. (SpringerNature, 2023-10-31)
Increasing salt production and use is shifting the natural balances of salt ions across Earth systems, causing interrelated effects across biophysical systems collectively known as freshwater salinization syndrome. In this Review, we conceptualize the natural salt cycle and synthesize increasing global trends of salt production and riverine salt concentrations and fluxes. The natural salt cycle is primarily driven by relatively slow geologic and hydrologic processes that bring different salts to the surface of the Earth. Anthropogenic activities have accelerated the processes, timescales and magnitudes of salt fluxes and altered their directionality, creating an anthropogenic salt cycle. Global salt production has increased rapidly over the past century for different salts, with approximately 300 Mt of NaCl produced per year. A salt budget for the USA suggests that salt fluxes in rivers can be within similar orders of magnitude as anthropogenic salt fluxes, and there can be substantial accumulation of salt in watersheds. Excess salt propagates along the anthropogenic salt cycle, causing freshwater salinization syndrome to extend beyond freshwater supplies and affect food and energy production, air quality, human health and infrastructure. There is a need to identify environmental limits and thresholds for salt ions and reduce salinization before planetary boundaries are exceeded, causing serious or irreversible damage across Earth systems.
Freshwater salinization syndrome limits management efforts to improve water quality
Maas, Carly M.; Kaushal, Sujay S.; Rippy, Megan A.; Mayer, Paul M.; Grant, Stanley B.; Shatkay, Ruth R.; Malin, Joseph T.; Bhide, Shantanu V.; Vikesland, Peter J.; Krauss, Lauren; Reimer, Jenna E.; Yaculak, Alexis M. (Frontiers, 2023-09-22)
Freshwater Salinization Syndrome (FSS) refers to groups of biological, physical, and chemical impacts which commonly occur together in response to salinization. FSS can be assessed by the mobilization of chemical mixtures, termed “chemical cocktails”, in watersheds. Currently, we do not know if salinization and mobilization of chemical cocktails along streams can be mitigated or reversed using restoration and conservation strategies. We investigated 1) the formation of chemical cocktails temporally and spatially along streams experiencing different levels of restoration and riparian forest conservation and 2) the potential for attenuation of chemical cocktails and salt ions along flowpaths through conservation and restoration areas. We monitored high-frequency temporal and longitudinal changes in streamwater chemistry in response to different pollution events (i.e., road salt, stormwater runoff, wastewater effluent, and baseflow conditions) and several types of watershed management or conservation efforts in six urban watersheds in the Chesapeake Bay watershed. Principal component analysis (PCA) indicates that chemical cocktails which formed along flowpaths (i.e., permanent reaches of a stream) varied due to pollution events. In response to winter road salt applications, the chemical cocktails were enriched in salts and metals (e.g., Na+, Mn, and Cu). During most baseflow and stormflow conditions, chemical cocktails were less enriched in salt ions and trace metals. Downstream attenuation of salt ions occurred during baseflow and stormflow conditions along flowpaths through regional parks, stream-floodplain restorations, and a national park. Conversely, chemical mixtures of salt ions and metals, which formed in response to multiple road salt applications or prolonged road salt exposure, did not show patterns of rapid attenuation downstream. Multiple linear regression was used to investigate variables that influence changes in chemical cocktails along flowpaths. Attenuation and dilution of salt ions and chemical cocktails along stream flowpaths was significantly related to riparian forest buffer width, types of salt pollution, and distance downstream. Although salt ions and chemical cocktails can be attenuated and diluted in response to conservation and restoration efforts at lower concentration ranges, there can be limitations in attenuation during road salt events, particularly if storm drains bypass riparian buffers.
Longitudinal stream synoptic monitoring tracks chemicals along watershed continuums: a typology of trends
Kaushal, Sujay S.; Maas, Carly M.; Mayer, Paul M.; Newcomer-Johnson, Tammy A.; Grant, Stanley B.; Rippy, Megan A.; Shatkay, Ruth R.; Leathers, Jonathan; Gold, Arthur J.; Smith, Cassandra; McMullen, Evan C.; Haq, Shahan; Smith, Rose; Duan, Shuiwang; Malin, Joseph; Yaculak, Alexis; Reimer, Jenna E.; Newcomb, Katie Delaney; Raley, Ashley Sides; Collison, Daniel C.; Galella, Joseph G.; Grese, Melissa; Sivirichi, Gwendolyn; Doody, Thomas R.; Vikesland, Peter J.; Bhide, Shantanu V.; Krauss, Lauren; Daugherty, Madeline; Stavrou, Christina; Etheredge, MaKayla; Ziegler, Jillian; Kirschnick, Andrew; England, William; Belt, Kenneth T. (Frontiers, 2023-06-09)
There are challenges in monitoring and managing water quality due to spatial and temporal heterogeneity in contaminant sources, transport, and transformations. We demonstrate the importance of longitudinal stream synoptic (LSS) monitoring, which can track combinations of water quality parameters along flowpaths across space and time. Specifically, we analyze longitudinal patterns of chemical mixtures of carbon, nutrients, greenhouse gasses, salts, and metals concentrations along 10 flowpaths draining 1,765 km2 of the Chesapeake Bay region. These 10 longitudinal stream flowpaths are drained by watersheds experiencing either urban degradation, forest and wetland conservation, or stream and floodplain restoration. Along the 10 longitudinal stream flowpaths, we monitored over 300 total sampling sites along a combined stream length of 337 km. Synoptic monitoring along longitudinal flowpaths revealed: (1) increasing, decreasing, piecewise, or no trends and transitions in water quality with increasing distance downstream, which provide insights into water quality processes along flowpaths; (2) longitudinal trends and transitions in water quality along flowpaths can be quantified and compared using simple linear and non-linear statistical relationships with distance downstream and/or land use/land cover attributes, (3) attenuation and transformation of chemical cocktails along flowpaths depend on: spatial scales, pollution sources, and transitions in land use and management, hydrology, and restoration. We compared our LSS patterns with others from the global literature to synthesize a typology of longitudinal water quality trends and transitions in streams and rivers based on hydrological, biological, and geochemical processes. Applications of LSS monitoring along flowpaths from our results and the literature reveal: (1) if there are shifts in pollution sources, trends, and transitions along flowpaths, (2) which pollution sources can spread further downstream to sensitive receiving waters such as drinking water supplies and coastal zones, and (3) if transitions in land use, conservation, management, or restoration can attenuate downstream transport of pollution sources. Our typology of longitudinal water quality responses along flowpaths combines many observations across suites of chemicals that can follow predictable patterns based on watershed characteristics. Our typology of longitudinal water quality responses also provides a foundation for future studies, watershed assessments, evaluating watershed management and stream restoration, and comparing watershed responses to non-point and point pollution sources along streams and rivers. LSS monitoring, which integrates both spatial and temporal dimensions and considers multiple contaminants together (a chemical cocktail approach), can be a comprehensive strategy for tracking sources, fate, and transport of pollutants along stream flowpaths and making comparisons of water quality patterns across different watersheds and regions.
Stormwater biofilter response to high nitrogen loading under transient flow conditions: Ammonium and nitrate fates, and nitrous oxide emissions
Feraud, Marina; Ahearn, Sean P.; Parker, Emily A.; Avasarala, Sumant; Rugh, Megyn B.; Hung, Wei-Cheng; Li, Dong; Van De Werfhorst, Laurie C.; Kefela, Timnit; Hemati, Azadeh; Mehring, Andrew S.; Cao, Yiping; Jay, Jennifer A.; Liu, Haizhou; Grant, Stanley B.; Holden, Patricia A. (Pergamon-Elsevier, 2022-12-17)
Nitrogen (N) in urban runoff is often treated with green infrastructure including biofilters. However, N fates across biofilters are insufficiently understood because prior studies emphasize low N loading under laboratory conditions, or use “steady-state” flow regimes over short time scales. Here, we tested field scale biofilter N fates during simulated storms delivering realistic transient flows with high N loading. Biofilter outflow ammonium (NH4+-N) was 60.7 to 92.3% lower than that of the inflow. Yet the characteristic times for nitrification (days to weeks) and denitrification (days) relative to N residence times (7 to 30 h) suggested low N transformation across the biofilters. Still, across 7 successive storms, total outflow nitrate (NO3−-N) greatly exceeded (3100 to 3900%) inflow nitrate, a result only explainable by biofilter soil N nitrification occurring between storms. Archaeal, and bacterial amoA gene copies (2.1 × 105 to 1.2 × 106 gc g soil−1), nitrifier presence by16S rRNA gene sequencing, and outflow δ18O-NO3− values (-3.0 to 17.1 ‰) reinforced that nitrification was occurring. A ratio of δ18O-NO3− to δ15N-NO3− of 1.83 for soil eluates indicated additional processes: N assimilation, and N mineralization. Denitrification potential was suggested by enzyme activities and soil denitrifying gene copies (nirK + nirS: 3.0 × 106 to 1.8 × 107; nosZ: 5.0 × 105 to 2.2 × 106 gc g soil−1). However, nitrous oxide (N2O-N) emissions (13.5 to 84.3 μg N m −2 h −1) and N2O export (0.014 g N) were low, and soil nitrification enzyme activities (0.45 to 1.63 mg N kg soil−1day−1) exceeded those for denitrification (0.17 to 0.49 mg N kg soil−1 day−1). Taken together, chemical, bacterial, and isotopic metrics evidenced that storm inflow NH4+sorbs and, along with mineralized soil N, nitrifies during biofilter dry-down; little denitrification and associated N2O emissions ensue, and thus subsequent storms export copious NO3−-N. As such, pulsed pass-through biofilters require redesign to promote plant assimilation and/or denitrification of mineralized and nitrified N, to minimize NO3−-N generation and export.
Solute Transport Through Unsteady Hydrologic Systems Along a Plug Flow-To-Uniform Sampling Continuum
Grant, Stanley B.; Harman, Ciaran J. (American Geophysical Union, 2022-08-22)
Unsteady transit time distribution (TTD) theory is a promising new approach for merging hydrologic and water quality models at the catchment scale. A major obstacle to widespread adoption of the theory, however, has been the specification of the StorAge Selection (SAS) function, which describes how the selection of water for outflow is biased by age. In this paper we hypothesize that some unsteady hydrologic systems of practical interest can be described, to first-order, by a “shifted-uniform” SAS that falls along a continuum between plug flow sampling (for which only the oldest water in storage is sampled for outflow) and uniform sampling (for which water in storage is sampled randomly for outflow). For this choice of SAS function, explicit formulae are derived for the evolving: (a) age distribution of water in storage; (b) age distribution of water in outflow; and (c) breakthrough concentration of a conservative solute under either continuous or impulsive addition. Model predictions conform closely to chloride and deuterium breakthrough curves measured previously in a sloping lysimeter subject to periodic wetting, although refinements of the model are needed to account for the reconfiguration of flow paths at high storage levels (the so-called inverse storage effect). The analytical results derived in this paper should lower the barrier to applying TTD theory in practice, ease the computational demands associated with simulating solute transport through complex hydrologic systems, and provide physical insights that might not be apparent from traditional numerical solutions of the governing equations.
Portable, low-cost samplers for distributed sampling of atmospheric gases
Hurley, James; Caceres, Alejandra; McGlynn, Deborah; Tovillo, Mary; Pinar, Suzanne; Schuerch, Roger; Onufrieva, Ksenia; Isaacman-VanWertz, Gabriel (2023-10-13)
Volatile organic compounds (VOCs) contribute to air pollution both directly, as hazardous gases, and through their reactions with common atmospheric oxidants to produce ozone, particulate matter, and other hazardous air pollutants. There are enormous ranges of structures and reaction rates among VOCs, and consequently a need to accurately characterize the spatial and temporal distribution of individual identified compounds. Current VOC measurements are often made with complex, expensive instrumentation that provides high chemical detail, but is limited in its portability and requires high expense (e.g., mobile labs) for spatially resolved measurements. Alternatively, periodic collection of samples on cartridges is inexpensive but demands significant operator interaction that can limit possibilities for time-resolved measurements or distributed measurements across a spatial area. Thus, there is a need for simple, portable devices that can sample with limited operator presence to enable temporally and/or spatially resolved measurements. In this work, we describe new portable and programmable VOC samplers that enable simultaneous collection of samples across a spatially distributed network, validate their reproducibility, and demonstrate their utility. Validation experiments confirmed high precision between samplers as well as the ability of miniature ozone scrubbers to preserve reactive analytes collected on commercially available adsorbent gas sampling cartridges, supporting simultaneous field deployment across multiple locations. In indoor environments, 24-hour integrated samples demonstrate observable day-to-day variability, as well as variability across very short spatial scales (meters). The utility of the samplers was further demonstrated by locating outdoor point sources of analytes through the development of a new mapping approach that employs a group of the portable samplers and back projection techniques to assess a sampling area with higher resolution than stationary sampling. As with all gas sampling, the limits of detection depend on sampling times and the properties of sorbent and analyte. Limit of detection of the analytical system used in this work is on the order of nanograms, corresponding to mixing ratios of 1-10 pptv after one hour of sampling at the programmable flow rate of 50-250 sccm enabled by the developed system. The portable VOC samplers described and validated here provide a simple, low-cost sampling solution for spatially and/or temporally variable measurements of any organic gases that are collectable on currently available sampling media.
Morphodynamic and modeling insights from global sensitivity analysis of a barrier island evolution model
Hoagland, Steven; Irish, Jennifer L.; Weiss, Robert (Elsevier, 2024-02)
Recently developed models of coastal barrier morphodynamics include marsh and lagoon processes that have been shown to impact barrier island evolution. To gain additional insights into the simulated barrier-backbarrier system dynamics, this study explores the parameter space of a barrier evolution model using global sensitivity analysis. Influential parameters, their interactions with one another, and regions of sensitivity within the parameter space were identified using Sobol indices and factor mapping techniques for model results through the end of the century. The results of this study highlight an important relationship between initial and critical barrier island geometries and suggest that narrow and low-relief barriers are most vulnerable to be eroded away (width drowning) or overtaken by sea level rise (height drowning), respectively. Width drowning was also strongly associated with other model input parameters such as toe depth, sea level rise rate, and backbarrier critical bed shear stress, which suggests that sub-centennial drowning is dependent on a unique combination of input parameter values and may be averted (or delayed) with a single input parameter change. Barrier dynamics were significantly influenced by the backbarrier marsh platform, which was more impacted by sediment transport parameters such as critical bed shear stress and ocean sediment concentration than maximum annual overwash flux. This suggests that inorganic sediment deposition through tidal inlet dispersion is much more significant to the backbarrier marsh and lagoon system than overwash over sub-centennial timescales and can help to reduce the risk of width drowning.
An Econometric Analysis to Explore the Temporal Variability of the Factors Affecting Crash Severity Due to COVID-19
Alrumaidhi, Mubarak; Rakha, Hesham A. (MDPI, 2024-02-01)
This study utilizes multilevel ordinal logistic regression (M-OLR), an approach that accounts for spatial heterogeneity, to assess the dynamics of crash severity in Virginia, USA, over the years 2018 to 2023. This period was notably influenced by the COVID-19 pandemic and its associated stay-at-home orders, which significantly altered traffic behaviors and crash severity patterns. This study aims to evaluate the pandemic’s impact on crash severity and examine the consequent changes in driver behaviors. Despite a reduction in total crashes, a worrying increase in the proportion of severe injuries is observed, suggesting that less congested roads during the pandemic led to riskier driving behaviors, notably increased speed violations. This research also highlights heightened risks for vulnerable road users such as pedestrians, cyclists, and motorcyclists, with changes in transportation habits during the pandemic leading to more severe crashes involving these groups. Additionally, this study emphasizes the consistent influence of environmental and roadway features, like weather conditions and traffic signals, in determining crash outcomes. These findings offer vital insights for road safety policymakers and urban planners, indicating the necessity of adaptive road safety strategies in response to changing societal norms and behaviors. The research underscores the critical role of individual behaviors and mental states in traffic safety management and advocates for holistic approaches to ensure road safety in a rapidly evolving post-pandemic landscape.
How has COVID-19 impacted customer perceptions and demand for delivery services: An exploratory analysis
Kaplan, Marcella; Hotle, Susan; Heaslip, Kevin (Elsevier, 2023-02-23)
The novel coronavirus (COVID-19) pandemic created an environment where nearly all aspects of mobility changed to ensure the health and safety of the public. The Centers for Disease Control and Prevention (CDC) recommended that people quarantine for 14 days if they were potentially exposed to the virus, stay at least six feet apart from others, and stay at home as much as possible. Delivery via third-party restaurant app, grocery, and package delivery quickly became an essential service. This study assesses customer's changes in use and perceived quality of delivery services in Southwest Virginia, via an online stated-preference survey (n = 423). The responses were analyzed using ordered logit and generalized ordered logit models to identify which population segments had changing delivery behavior and perceptions due to the pandemic. Findings include that before the pandemic, only households with an income greater than $100,000 had a significantly higher demand for package delivery services than those making less than $25,000. During the pandemic, all income brackets had a significantly higher demand for package delivery “weekly” than households with less than a $25,000 income, with a 19.50%, 22.54%, and 45.59% greater chance of use for income levels $25,000 to $50,000, $50,000 to $100,000, and over $100,000, respectively. This trend highlights that package delivery became necessary during the pandemic. Respondents who lived within town limits were statistically significantly more likely to use third-party restaurant delivery apps at least once a week before (3.10%), during (9.20%), and after (4.50%) the pandemic compared to those outside town limits. The results also found people who lived within town limits were 7.77% more likely to be satisfied with delivery services in general than those who lived outside town limits. The findings from this paper identify expanding delivery equity gaps within the population and provide recommendations for policymakers and delivery agencies. Some limitations include that low sample size did not allow for fully segmented models and meant that the study should be considered exploratory in nature.
Monte Carlo Simulation of Barrier-Island Systems and Tsunami Hazards
Irish, Jennifer L.; Weiss, Robert; Dura, Tina (Coastal Engineering Research Council, 2023-09-01)
Robust characterization of the future tsunami hazard is critically important for resilient planning and engineering in coastal communities prone to tsunami inundation. The hazard from earthquake-generated tsunami waves is not only determined by the earthquake's characteristics and distance to the earthquake area, but also by the geomorphology of the nearshore and onshore areas, which can change over time. In coastal hazard assessments, a changing coastal environment is commonly taken into account by increasing the sea-level to projected values (static). However, sea-level changes and other climate-change impacts influence the entire coastal system causing morphological change (dynamic). Here, we present the modeling framework and results initially published in Weiss et al. (2022), which employs within a Monte Carlo framework the barrier island-marsh, lagoon- marsh evolution model of Lorenzo-Trueba and Mariotti (2017) and the tsunami model Geoclaw (e.g., LeVeque et al. 2011). We compare the runup of the same suite of earthquake-generated tsunamis to a barrier system for statically adjusted and dynamically adjusted sea level and bathymetry over the period from 2000 to 2100. We employ Representative Concentration Pathways 2.6 and 8.5 without and with treatment of Antarctic ice-sheet processes (e.g., Kopp et al. 2017) as different sea-level projections.
Real-Time Prediction of Alongshore Near-Field Tsunami Runup Distribution From Heterogeneous Earthquake Slip Distribution
Lee, Jun-Whan; Irish, Jennifer L.; Weiss, Robert (American Geophysical Union, 2023-01-05)
Real-time tsunami prediction is necessary for tsunami forecasting. Although tsunami forecasting based on a precomputed tsunami simulation database is fast, it is difficult to respond to earthquakes that are not in the database. As the computation speed increases, various alternatives based on physics-based models have been proposed. However, physics-based models still require several minutes to simulate tsunamis and can have numerical stability issues that potentially make them unreliable for use in forecasting—particularly in the case of near-field tsunamis. This paper presents a data-driven model called the tsunami runup response function for finite faults (TRRF-FF) model that can predict alongshore near-field tsunami runup distribution from heterogeneous earthquake slip distribution in less than a second. Once the TRRF-FF model is trained and calibrated based on a discrete set of tsunami simulations, the TRRF-FF model can predict alongshore tsunami runup distribution from any combination of finite fault parameters. The TRRF-FF model treats the leading-order contribution and the residual part of the alongshore tsunami runup distribution separately. The interaction between finite faults is modeled based on the leading-order alongshore tsunami runup distribution. We validated the TRRF-FF modeling approach with more than 200 synthetic tsunami scenarios in eastern Japan. We further explored the performance of the TRRF-FF model by applying it to the 2011 Tohoku (Japan) tsunami event. The results show that the TRRF-FF model is more flexible, occupies much less storage space than a precomputed tsunami simulation database, and is more rapid and reliable than real-time physics-based numerical simulation.
Queue Length Estimation and Optimal Vehicle Trajectory Planning Considering Queue Effects at Actuated Traffic Signal Controlled Intersections
Shafik, Amr; Rakha, Hesham A. (2024-01-08)
This research explores the implementation and evaluation of a green light optimal speed advisory (GLOSA) system in proximity to actuated traffic signals, considering the inherent uncertainty in switching times. Additionally, the impact of surrounding traffic is considered by optimizing vehicle trajectories with real-time queue estimation, derived from both loop-detector and probe vehicle data. Through comprehensive simulation experiments involving a single vehicle approaching an intersection with queued vehicles, as well as network-level simulations covering various market penetration levels (ranging from 0% to 100%), the fuel savings achieved by the GLOSA system is quantified. The results demonstrate substantial fuel savings of 31.4% and 35.4% when optimizing without and with consideration of the queueing process, respectively, from the perspective of individual vehicles. Furthermore, from a network-wide standpoint, a total fuel saving of 19.7% is observed for both scenarios. In addition, the optimization algorithm with considering the queuing process resulted in less average number of stops per vehicle than the case without considering it. Notably, the integration of the queue estimation yields remarkable improvements in system performance from the perspective of individual vehicles. However, it is found that considering the queue effects does not lead to an overall enhancement in system performance from a network-wide perspective. This research highlights the benefits and underscores the limitations of the GLOSA system when considering surrounding traffic. The incorporation of real-time queueing information for trajectory optimization offers valuable insights for the deployment and advancement of connected vehicle systems in real-world traffic environments.
Impacts of Vehicle-to-Everything Enabled Applications: Literature Review of Existing Studies
Du, Jianhe; Ahn, Kyoungho; Farag, Mohamed; Rakha, Hesham A. (Universal Wiser Publisher, 2023-03-10)
As communication technology is developing at a rapid pace, connected vehicles (CVs) can potentially enhance vehicle safety while reducing vehicle energy consumption and emissions via data sharing. Many researchers have attempted to quantify the impacts of such CV applications and vehicle-to-everything (V2X) communication, or the instant and accurate communication among vehicles, devices, pedestrians, infrastructure, network, cloud, and grid. Cellular V2X (C-V2X) has gained interest as an efficient method for this data sharing. In releases 14 and 15, C-V2X uses 4G LTE technology, and in release 16, it uses the latest 5G new radio (NR) technology. Among its benefits, C-V2X can function even with no network infrastructure coverage; in addition, C-V2X surpasses older technologies in terms of communication range, latency, and data rates. Highly efficient information interchange in a CV environment can provide timely data to enhance the transportation system's capacity, and it can support applications that improve vehicle safety and minimize negative impacts on the environment. Achieving the full benefits of CVs requires rigorous investigation into the effectiveness, strengths, and weaknesses of different CV applications. It also calls for deeper understanding of the communication protocols, results with different CV market penetration rates (MPRs), CV- and human-driven vehicle interactions, integration of multiple applications, and errors and latencies associated with data communication. This paper includes a review of existing literature on the safety, mobility, and environmental impacts of CV applications; gaps in current CV research; and recommended directions for future research. The results of this paper will help shape future research for CV applications to realize their full potential.
Relating Geotechnical Sediment Properties and Low Frequency CHIRP Sonar Measurements
Jaber, Reem; Stark, Nina; Sarlo, Rodrigo; McNinch, Jesse E.; Massey, Grace (MDPI, 2024-01-08)
Low frequency acoustic methods are a common tool for seabed stratigraphy mapping. Due to the efficiency in seabed mapping compared to geotechnical methods, estimating geotechnical sediment properties from acoustic surveying is attractive for many applications. In this study, co-located geotechnical and geoacoustic measurements of different seabed sediment types in shallow water environments (<5 m of water depth) are analyzed. Acoustic impedance estimated from sediment properties based on laboratory testing of physical samples is compared to acoustic impedance deduced from CHIRP sonar measurements using an inversion approach. Portable free fall penetrometer measurements provided in situ sediment strength. The results show that acoustic impedance values deduced from acoustic data through inversion fall within a range of ±25% of acoustic impedance estimated from porosity and bulk density. The acoustic measurements reflect variations in shallow sediment properties such as porosity and bulk density (~10 cm below seabed surface), even for very soft sediments (s_u < 3 kPa) and loose sands (~20% relative density). This is a step towards validating the ability of acoustic methods to capture geotechnical properties in the topmost seabed layers.
Simulation of Flood-Induced Human Migration at the Municipal Scale: A Stochastic Agent-Based Model of Relocation Response to Coastal Flooding
Nourali, Zahra; Shortridge, Julie E.; Bukvic, Anamaria; Shao, Yang; Irish, Jennifer L. (MDPI, 2024-01-11)
Human migration triggered by flooding will create sociodemographic, economic, and cultural challenges in coastal communities, and adaptation to these challenges will primarily occur at the municipal level. However, existing migration models at larger spatial scales do not necessarily capture relevant social responses to flooding at the local and municipal levels. Furthermore, projecting migration dynamics into the future becomes difficult due to uncertainties in human–environment interactions, particularly when historic observations are used for model calibration. This study proposes a stochastic agent-based model (ABM) designed for the long-term projection of municipal-scale migration due to repeated flood events. A baseline model is demonstrated initially, capable of using stochastic bottom-up decision rules to replicate county-level population. This approach is then combined with physical flood-exposure data to simulate how population projections diverge under different flooding assumptions. The methodology is applied to a study area comprising 16 counties in coastal Virginia and Maryland, U.S., and include rural areas which are often overlooked in adaptation research. The results show that incorporating flood impacts results in divergent population growth patterns in both urban and rural locations, demonstrating potential municipal-level migration response to coastal flooding.
Comparative analysis of alternative powertrain technologies in freight trains: A numerical examination towards sustainable rail transport
Aredah, Ahmed; Du, Jianhe; Hegazi, Mohamed; List, George; Rakha, Hesham A. (Elsevier, 2024-02-15)
This study assesses the energy efficiency and environmental implications of six powertrain technologies in the U.S. freight rail network: diesel, biodiesel, diesel-hybrid, biodiesel-hybrid, hydrogen fuel cell, and electric. Utilizing a simulation model, energy consumption at the tank across different demand scenarios and geographical regions is conducted. The study revealed electric powertrains as the standout, slashing energy consumption at the tank by 56% compared to traditional diesel, with the potential for zero CO2 emissions when powered by green energy sources. Biodiesel and biodiesel-hybrid also outperformed conventional diesel, cutting CO2 tank emissions by 6% and 21%, respectively. Diesel-hybrid registered a 16% reduction in both tank energy and diesel consumption, while hydrogen fuel cells demonstrated a 15% energy consumption drop at the tank and zero emissions. Implementing these advanced technologies requires considerable infrastructure investment and adaptation, which is beyond the scope of our analysis. While centered on the U.S. rail network, our findings offer valuable insights for global freight rail systems, underpinning the push for sustainable powertrain transitions.
ARGem: a new metagenomics pipeline for antibiotic resistance genes: metadata, analysis, and visualization
Liang, Xiao; Zhang, Jingyi; Kim, Yoonjin; Ho, Josh; Liu, Kevin; Keenum, Ishi M.; Gupta, Suraj; Davis, Benjamin; Hepp, Shannon L.; Zhang, Liqing; Xia, Kang; Knowlton, Katharine F.; Liao, Jingqiu; Vikesland, Peter J.; Pruden, Amy; Heath, Lenwood S. (Frontiers, 2023-09-15)
Antibiotic resistance is of crucial interest to both human and animal medicine. It has been recognized that increased environmental monitoring of antibiotic resistance is needed. Metagenomic DNA sequencing is becoming an attractive method to profile antibiotic resistance genes (ARGs), including a special focus on pathogens. A number of computational pipelines are available and under development to support environmental ARG monitoring; the pipeline we present here is promising for general adoption for the purpose of harmonized global monitoring. Specifically, ARGem is a user-friendly pipeline that provides full-service analysis, from the initial DNA short reads to the final visualization of results. The capture of extensive metadata is also facilitated to support comparability across projects and broader monitoring goals. The ARGem pipeline offers efficient analysis of a modest number of samples along with affordable computational components, though the throughput could be increased through cloud resources, based on the user’s configuration. The pipeline components were carefully assessed and selected to satisfy tradeoffs, balancing efficiency and flexibility. It was essential to provide a step to perform short read assembly in a reasonable time frame to ensure accurate annotation of identified ARGs. Comprehensive ARG and mobile genetic element databases are included in ARGem for annotation support. ARGem further includes an expandable set of analysis tools that include statistical and network analysis and supports various useful visualization techniques, including Cytoscape visualization of co-occurrence and correlation networks. The performance and flexibility of the ARGem pipeline is demonstrated with analysis of aquatic metagenomes. The pipeline is freely available at https://github.com/xlxlxlx/ARGem.
TUNEOPT: An Evolutionary Reinforcement Learning HVAC Controller For Energy-Comfort Optimization Tuning
Meimand, Mostafa; Khattar, Vanshaj; Yazdani, Zahra; Jazizadeh, Farrokh; Jin, Ming (ACM, 2023-11-15)
HVAC systems account for the majority of energy consumption in buildings. Efficient control of HVAC systems can reduce energy consumption and enhance occupants’ comfort. In the existing literature, energy-comfort or cost-comfort co-optimization frameworks commonly involve manual tuning of the balancing coefficient between energy and comfort through parameter tuning by an expert. Nevertheless, achieving the optimal balance between energy usage and occupant comfort remains challenging. This limitation restricts the generalizability of different formulations across various scenarios or testing on different environments. In this paper, we propose an implicit evolutionary Reinforcement Learning (RL) approach to learn and adapt the trade-off parameter of an energy-comfort optimization formulation. We have developed a predictive comfortenergy co-optimization formulation for controlling the setpoint of a building. The RL agent utilizes a novel guidance-induced random search method to learn the energy-comfort trade-off coefficient and guide the optimization formulation. The reward function of the RL model is energy productivity (comfort over energy consumption). To evaluate the feasibility of our proposed approach, we conducted experiments on a real-world testbed - i.e., an apartment unit. Our feasibility study shows that the proposed approach can learn an optimal control parameter and reduce energy consumption by 24.3% while decreasing comfort by only 1% compared to the baseline.

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