Browsing by Author "Lucero, Christian"

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    The Application of Laser Technology for Railroad Top of Rail (TOR) Friction Modifier Detection and Measurements
    Singh, Dejah Leandra (Virginia Tech, 2018-05-16)
    The examination of the application and accuracy of optical sensors for the purpose of determining rail lubricity of top-of-rail friction modifier is investigated in this research. A literature review of optical sensors as they relate to detecting thin layers is presented, as well as a literature review of the significant aspect of surface roughness on optical signature. Both commercially available optical sensors and optical devices, such as independent lasers and detectors, are examined in a comprehensive parametric study to determine the most suitable configuration for a prototype with adequate third-body detection. A prototype is constructed considering parameters such as sunlight contamination, vibrations, and angle of detection. The prototype is evaluated in a series of laboratory tests with known lubricity conditions for its accuracy of measurements and susceptibility to environmental conditions, in preparation for field testing. Upon field testing the prototype, the data indicates that it is capable of providing subjective measurements that can help with determining whether a rail is highly lubricated or unlubricated, or it is moderately lubricated. It is anticipated that the device could be used to provide a rail lubricity index. The investigation of the optical response of a rail in various conditions, including top-of-rail friction modifier presence and underlying surface roughness, reveals the behavior of friction modifying material on rail/wheel interactions. It is determined that surface roughness is imperative for distinguishing between scattering due to surface condition and scattering due to third-body layers. Additionally it is revealed that friction modifying materials become entrapped within the surface roughness of the rail, effectively causing a "seasoning" effect instead of a simple third body layer. This provides some explanation on the inadequacy of determining lubricity conditions using contacting methods since they cannot detect the entrapped material that are revealed only when the top of rail undergoes a micro deformation due to a passing wheel. Furthermore, the fluorescent signature of flange grease can be utilized to detect any flange grease contamination on top of rail. The results of the study indicate that it is possible to have practical optical sensors for top-of-rail third body layer detection and any contamination that may exist, initially through spot checking the rail and eventually through in-motion surveying.
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    Virginia Tech Food Access and Security Study
    Hall, Ralph P.; Ranganathan, Shyam; Agnew, Jessica L.; Christie, Maria Elisa; Kirk, Gary R.; Lucero, Christian; Clark, Susan F.; Archibald, Thomas G. (Virginia Tech, 2019-10-30)
    There is growing evidence to suggest that a substantial number of college and university students in the United States grapple with food insecurity during their studies. One of the most comprehensive surveys on this issue was conducted by The Hope Center with 33 participating four-year institutions. They estimated that 41% of students had low or very low food security (Goldrick-Rab et al. 2019). A review of food security studies by the U.S. Government Accountability Office (GAO) (2018) found similar results and that few students who qualified for food assistance were aware of federal food assistance programs such as the Supplemental Nutritional Assistance Program (SNAP). In response to the increasing concern over students’ access to food, this study aims to document food security at Virginia Tech. The study was designed with two parallel goals: to contribute to the national conversation on food access and security amongst higher education students; and to inform a strategic response through data-informed programs and policies at Virginia Tech. The first phase of the study was conducted between Fall 2017 and Spring 2018 and consisted of semi-structured key informant interviews. The second phase was conducted between December 2018 and January 2019 and consisted of an anonymous survey distributed to 32,242 students (27,421 undergraduate and 4,821 graduate) located in Blacksburg. A total of 2,441 (8.9%) undergraduate and 589 (12.2%) graduate students completed the entire survey (for a combined response rate of 9.4%). This study finds that 29% (±3.8%) of undergraduate and 35% (±7%) of graduate students were classified as having low or very low food security based on the USDA food security instrument. These findings are comparable with The Hope Center study (Goldrick-Rab et al. 2019). Students with low/very low food security status were more likely to be Hispanic/Latino or Black/African American, be receiving a Pell grant or financing their education through sources that need to be repaid, have a low GPA, and/or have a disability. Graduate students were also more likely than undergraduate students to be unable to afford to eat balanced meals or have to cut the size of their meals due to a lack of available funds. In general, the proportion of graduate students experiencing food-access problems was greater than the proportion of undergraduate students. A diet diversity score (DDS) was also developed from the student survey to measure the foods consumed by an individual within the previous 24 hours. The DDS is a proxy for dietary quality and helps provide insight into the barriers that students might face in accessing nutritious foods. The study found that on average students classified as having low/very low food security also had a lower DDS. This finding confirms that low food security is associated with a lower diet quality in addition to not having access to enough food. Students who reported that they sometimes or often did not have enough to eat in the past 12 months were also asked if they have received benefits from a range of food assistance programs. Of the 219 students who were asked this question, only 9% (n=20) reported receiving some form of assistance. When asked why they had not used a food assistance program, the primary response was that they felt other people needed more assistance than they did. The next three most selected reasons were a lack of awareness about (1) whether they were eligible for a food assistance program, (2) what programs exist, and (3) whom to speak with about what resources are available. These findings are consistent with the GAO (2018) report. These results reveal that students who potentially need food assistance may not know where to look for help, and administrative and/or social barriers related to existing on- and off-campus services may prevent students from seeking help even if they know it is available. This report also documents a range of on- and off-campus food assistance services that are available for students and provides a summary of the feedback obtained from the key informant interviews on potential next steps that could be taken by Virginia Tech. These steps include enhancing the coordination among, and awareness of, existing food assistance programs on and off campus, and new ideas such as creating an on-campus food pantry or subsidizing the cost of dining for students in need. Regardless of which actions are taken, we believe this report reveals our collective responsibility to ensure that no student at Virginia Tech goes hungry or is unable to access nutritious foods, and to create a community that nurtures learning and growth for all of its members.