Environmental and Occupational Health Sciences Institute
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A machine learning framework for predicting failures in rail infrastructure assets
No full textInfrastructure safety is crucial for the rail industry, with signal functionality and track integrity being among essential components. This thesis presents a machine learning framework to predict failures in rail infrastructure assets, focusing on two critical areas: urban rail transit signal failures and broken rails in commuter rail systems. Integrating historical failure data, maintenance data, and track condition data, and operational data, the proposed framework applies machine learning models to identify high-risk locations and predict rail asset failures. Because rail infrastructure asset failures are relatively rare, imbalanced data mining techniques such as SMOTE, ADASYN, and random resampling are also employed to improve predictive accuracy. In the first case study, our model achieves an AUC of 75% and demonstrates the ability to identify approximately one-third of rail signal failures by focusing on 10% of signal locations on the network within the one-month prediction period. Our second case study focused on commuter rail segments, in which our model gives an AUC of 74% and 71% overall accuracy. The results show the potential of this framework to identify high-risk hot spots for prioritized inspection and maintenance, given limited resources.M.S.Includes bibliographical reference
A novel ionizer design for detector length compensation in time-of-flight energy analysis of molecular beams
No full textThis dissertation presents preliminary analysis of the cyclooctatetraene (COT) on Cu(001) adsorption system with angle-resolved helium atom scattering (HAS) and scanning tunneling microsopy (STM). A novel ionizer design and mass spectrometer orientation concept for time-of-flight (TOF) analysis of helium atoms is introduced. Implementation of the novel detector and optimization of TOF resolution is shown. Studies of the COT on Cu(001) adsorption system with HAS initially revealed a high-order commensurate superstructure with unit cell vectors of [6 1, 1 3] relative to the 4-fold substrate periodicity. Desorption measurements using HAS showed COT undergoes first order desorption at 570 K. Further analysis with HAS and STM at various adsorbate coverages, as well as DFT calculations, suggest that COT has one allowed adsorption site which is centered between four substrate atoms. At high coverages, COT primarily forms short-ranged ordered domains with unit cells of [3 1, 1 3] with domain boundaries of [3 0, 1 3]. The highly sensitive ionizer design achieves high TOF energy resolution with a long ionization region through a new mass spectrometer orientation and compensation of neutral arrival times of the scattered helium beam. A mass resolving quadrupole mass spectrometer orientation is reversed from the conventional sense, such that the neutral beam first passes the electron multiplier, then travels through the quadrupole region before finally passing through the ionization region. The concept is illustrated here with application to the TOF He atom detector. A carefully selected compensating variable potential curve is applied to the ionization region so that as helium progresses through the ionization region the ions are created with ever increasing ion energies. Thus, all ions from the same section of the helium beam will be detected at the same time. Compensation is also possible with high electron space charge, allowing for increased ionization efficiency through both a larger ionization volume and higher electron densities within the ionizer.Ph.D.Includes bibliographical reference
On the dynamics of Caribbean through-flow water mass transport
No full textThe Caribbean Through-Flow (CTF) is an important component of Earth’s climate system as it organizes and transports significant heat, salt, and freshwater fluxes from two major circulation systems, the North Atlantic Subtropical Gyre (NASTG) and the Atlantic Meridional Overturning Circulation (AMOC). This dissertation on the dynamics of water mass transport of the CTF was motivated by two factors: (1) the observed and projected changes in the circulation systems both feeding and fed by the CTF and (2) the scarcity of subsurface observations and corresponding analyses in this region in recent decades. The research presented in the second chapter of this dissertation takes a step towards constraining CTF water mass transport pathways. Several deployments of autonomous underwater gliders in the largest and deepest Caribbean island passage revealed the total transport and the transport of South Atlantic Water, representing AMOC return flow, are likely larger than previously estimated. Further, usage of a glider with an acoustic doppler profiler was shown to be a viable method for measuring island passage water mass transport. The third chapter of this dissertation compiles all available temperature and salinity profiles collected in the CTF since 1960 and performs a decadal water mass analysis. This investigation revealed significant changes have occurred in the upper ocean water mass properties of the CTF which has implications for tropical cyclones, sea level rise, marine ecosystems, and downstream water mass formation in both the NASTG and the AMOC. The fourth chapter of this dissertation begins to expand beyond the constraints of the existing observational record in the CTF by utilizing high-resolution ocean reanalysis data to understand the spatial and temporal variability in water mass structure. This work details the westward modification of water mass structure in the CTF and shows the importance of this modification for the climatically important net heat, salt, and freshwater transport through this region. Ultimately, this dissertation improves our understanding of water mass transport dynamics in the CTF, documents regional climate change, and provides context for expanding the impacts of these changes globally.Ph.D.Includes bibliographical reference
Investigating tRNA-Val-CAC-1-1: acting as a tRNA or tRF in Drosophila melanogaster
No full textAnimal development is regulated by the organismal genes. These genes are broadly divided into protein coding and non-coding DNA. The latter in comprised of different functional groups, here we focus on investigating the role of transfer RNA (tRNA) in posttranscriptional gene regulation. Some tRNAs can function as tRNA fragments (tRFs). These RNAs act similarly to miRNAs by regulating mRNAs post transcriptionally. The tRNA:Val-CAC-1-1 (ValT) (CR31572) was computationally predicted as tRF in Drosophila melanogaster. One of the predicted 51 targets is Sprouty (Sty), a known negative regulator of the epidermal growth factor receptor (EGFR) signaling pathway. We performed experiments aiming to determine whether ValT acts as tRNA and/or tRF. Using genome engineering, CRISPR/Cas9, the following modifications were done in ValT, including eliminating either its normal tRNA or tRF function by changing the predicted tRF or anticodon domains. All substituted ValTs were homozygous viable. In delta ValT, we expected to see an increase in Sty, which in turn decreases EGFR signaling. Yet, the predicted eggshell phenotypes, which are sensitive to changes in EGFR signaling, were not consistent among the mutants, and no significant change was observed. Next, to achieve a better understanding of ValT functions, all transgenic lines were analyzed by RNAseq. We found groups of genes that were transcribed at different levels that were consistent across mutations in the tRF and others that were consistent across anticodon substitutions. These genes indicate potential targets for future studies into the function of ValT as a tRNA and a tRF.M.S.Includes bibliographical reference
Welcome to Rutgers: a study of the efficacy of Byrne first-year seminars at Rutgers University
No full textFirst-year seminars (FYS) were originally introduced as a formal course type in the early 1980s, and have become increasingly popular as a means to ease the transition from high school to college, and enhance undergraduate student success (Culver & Bowman, 2019; Porter & Swing, 2006). Studies of individual FYS programs suggest that students can gain numerous benefits from participating when the seminars are tailored to specific institutional needs. Rutgers-New Brunswick implemented its own unique first-year seminar program in 2007 as part of a larger initiative to reorganize campus-wide operations and enhance the undergraduate experience. This study aims to understand students’ experiences in the Byrne Seminars Program, and to assess its effects on their transition from high school to college, sense of belonging at Rutgers, and academic success. Using a framework of sense of belonging and social capital theories, this mixed-methods study analyzes program outcome data, student course evaluations, surveys, and focus group interviews to assess the Program’s efficacy. The findings from this study provide insight into the first-year student experience at Rutgers and the ways in which the Byrne Seminars can offer unique benefits such as discovering a major or minor, peer and faculty networking, and introduction to research, which may improve overall student satisfaction and success. The findings will also help guide changes to the Program which can make it more responsive to students’ needs and further contribute to undergraduate success at Rutgers-New Brunswick.Ed.D.Includes bibliographical reference
Phenomenological Investigations of Dark Matter’s Particle Nature with the Fermi Galactic Center GeV Excess and gaia wide binaries
No full textAstrophysical systems provide us with information regarding dark matter's particle nature that is inaccessible to Earth-based experiments. In this thesis, we study two such astrophysical systems: an unexplained source of GeV-scale gamma-rays known as the Fermi Galactic Center Excess (GCE) and wide binary star systems. First, we present a novel, data-driven characterization of the GCE using a flexible, non-parametric machine learning model -- the Gaussian process (GP). Unlike models used in past studies, the GP does not assume a particular spatial morphology for the GCE, instead inferring it from the data alone and hence providing a deeper understanding of the systematics associated with the GCE's interpretation as a product of annihilating DM. We discover new morphological features in our fits, such as a localized bright source at around (l,b) = (20°, 0°) and a diagonal arm extending Northwest from the Galactic Center. In spite of these features, our fitted GP can be explained in part by annihilating DM. Second, we use binaries measured by the Gaia satellite to constrain the properties of DM subhalos that may exist in the Milky Way, providing model-independent limits of DM particle physics. We set limits on generic subhalos with masses 10² - 10⁸ M☉ and radii ≲ 100 pc, with the most compact halos being the most constrained. However, subhalos with NFW density profiles as predicted by ΛCDM are not compact enough to be constrained, instead requiring ~5,000 times higher densities for limits to exist.Ph.D.Includes bibliographical reference
Exploration of self-assembled carbon nanomaterials through various dimensions
No full textThe realm of the carbon nanomaterials (CNMs) runs extremely deep and spans many members: nanotubes (CNTs), graphene, buckminsterfullerenes, carbon dots, graphene oxide (GO), nanodiamond, nanoribbons, carbon fibre, nano-onions, peapods, nanobuds, and new members graphyne and fullertubes, with nanotubes, buckminsterfullerenes, and graphene being the most famous of CNM family. They have a plethora of applications ranging from bioimaging to display technology to sensors. In this thesis, we filled carbon nanotubes with fullerenes and metallofullerenes (Lu and Gd) and obtained visual confirmation of this via high resolution scanning transmission electron microscopy. Additionally, we obtained baseline Raman measurements. These filled carbon nanotubes, which are called peapods, were made dispersible in water via a reaction with potassium metal. Then, more measurements via AFM, STEM, Raman, UV-Vis, and others were to help understand and confirm the dispersibility of the peapods. As a wrap-up, we did magnetic resonance imaging (MRI) to test the performance of the water dispersible Gd filled peapods and compared it to OmniscanTM. Here, it proved to have about 6x the contrast ability over OmniscanTM. Also, I functionalized C60 with complementary H-bonding ligands for self-assembly and attempted to covalently link C60 to the surface exfoliated graphite. Then, we move to a summary of fullerene formation, collaborative works involving XPS/STEM/EELS, and miscellaneous projects that did not pan out to wrap it all up.Ph.D.Includes bibliographical reference
Rapid Repair and Strengthening Procedures for Plain, Reinforced, and Prestressed Concrete Structural Elements
No full textConcrete has become the most widely consumed material on Earth after water. The volume of concrete consumed globally has tripled during the last two decades as more developing countries are expanding their infrastructure. In the developed countries, continuous efforts are made in the maintenance of the built environment. The prominent use and maintenance of concrete is in transportation and industrial infrastructure. The results presented in this dissertation focus on maintenance, mainly, repairing and strengthening the plain, reinforced, and the prestressed concrete structures. The information is developed primarily using the bridge structures. The three focus areas of the study are the cementitious repair materials with short fibers, reinforced concrete, and prestressed concrete. The repair and maintenance in concrete bridges is needed due to the damages induced by weather conditions, overloading, and vehicle collisions. Most common damages in the concrete are patches or potholes on the pavements, bridge decks or girders. Incidents involving structural damage due to vehicle collisions may also represent emergency scenarios leading to traffic closure and requiring immediate repair beyond a patch repair owing to the loss of reinforcement. The cementitious repair materials used according to the current standards are known to disintegrate over longer periods. Additionally, there is a lack of thorough guidelines and fundamental understanding for structural repairs of bridge girders damaged with loss of reinforcement during service. In lieu of such guidelines, transportation agencies are left with limited repair solutions either primitive or advanced. Practical, robust, fast, and low-cost structural repair solutions along with durable repair materials for damaged concrete in general, are thus necessary for safety and serviceability of concrete structures. The first goal of the study was to identify the most efficient cementitious repair materials. Based on the extensive literature and experimentation, material groups with three cement matrices were identified. The focus was to provide a workable repair material with good toughness characteristics achieved through addition of discrete polyvinyl alcohol (PVA) fibers. Compositions were developed with higher fiber dosage of 3 - 4 % and with lower dosage of 0 – 2% for application in horizontal, vertical, and overhead repair applications. Selected formulations were evaluated for their durability including cracking resistance with samples in field exposure in New Jersey. Detailed design procedures based on first principles of bending theory are developed using the current code of practice for structural repair of damaged prestressed and reinforced concrete girders using carbon fiber reinforced plastics (CFRP). The application of the proposed repair procedures on available experimental studies from literature is verified. Non-linear analysis of cracked prestressed girder along with modified equation for cracking moment capacity of standard prestressed girders is also proposed. The experimental results provided three formulations with toughness characteristics in bending with calcium sulfo-aluminate (CSA) cement-based matrix suited for horizontal repairs. A total of three other formulations for overhead and vertical repairs with two other rapid setting cements are identified entirely preventing the restrained shrinkage cracking as observed during nearly 3 years of age in field conditions. Other formulations in field exposure with CSA cement reported total crack widths of as low as 0.004 inches. The application of design procedures developed for structural repairs and strengthening using CFRP are reported to be in good standing with published experimental studies. The debonding of FRP at the debonding strain of 0.005 is identified as most probable mode of failure. The design procedures can be used to satisfy the ductility requirements of current codes of practice. Significant increase in cracking moment capacity of standard AASHTO girders is observed using the modified approach to serviceability analysis of prestress concrete girders.Ph.D.Includes bibliographical referencesIncludes vit
Stratospheric sulfate aerosol climate intervention implications for global agriculture
No full textAs the severity of climate change and its associated impacts continue to worsen, schemes for artificially cooling surface temperatures via planetary albedo modification are being studied. The method with the most attention in the literature is stratospheric sulfate aerosol climate intervention (SAI). Placing reflective aerosols in the stratosphere would have profound impacts on the entire Earth system, with potentially far-reaching societal impacts. This intervention strategy would impact crop production differently in different nations and would depend on the temperature target chosen. In this work, impacts on national maize, rice, soybean and wheat production were analyzed by looking at output from 11 different SAI scenarios carried out with a fully coupled Earth system model integrated with a crop model. Higher-latitude nations tend to produce the most calories under unabated climate change, while midlatitude nations maximize calories under moderate SAI implementation and equatorial nations produce the most calories from crops under high levels of SAI.However, there is crop-model-related uncertainty as to how SAI would impact global agriculture. Here, three global gridded process-based crop models were forced by output of one SAI scenario to better understand the potential impacts on global maize productivity. Future SAI implementation relative to a climate change scenario benefits global maize productivity ranging between 0% and 11% depending on the crop model.
SAI would create an unprecedented climate where the relationship between surface temperatures and carbon dioxide concentrations are decoupled. The implications of this intervention for global crop protein concentrations have not yet been explored. Changes of global wheat, rice, soybean, and maize protein concentrations under climate change and sulfate aerosol climate intervention were simulated by global gridded crop models. Maintaining elevated CO2 while reducing surface temperature increases with sulfate aerosol intervention would create small decreases to the protein concentrations of maize and rice, while wheat and soybean are minimally impacted. These decreases to protein under climate intervention partially offset any benefits to maize and rice yield.Ph.D.Includes bibliographical referencesIncludes vit
Eeskw Nutapimun: Nanticoke and Lenape fluid sovereignties
No full textThis dissertation project explores how Nanticoke and Lenape sovereignties, distributed through the people in broadly dispersed communities, becomes salient through their interactions. My research disrupts the concept of sovereignty as being tied to specific territory and polity, challenging the separation and boundedness of colonial sovereignties. I explore sovereignty across different geographies and temporalities, through communication, care, and choreography. I completed approximately 26 months of fieldwork, conducting interviews and participant observation with interlocutors primarily centered within the three Delaware Bay sister communities: the Nanticoke Indian Tribe, the Lenape Indian Tribe of Delaware, and the Nanticoke Lenni-Lenape Tribal Nation. In addition, I conducted interviews and participant observation with interlocutors from other Lenape communities including Munsee-Delaware Nation, Eelūnaapèewii Lahkèewiit, Stockbridge-Munsee Community Band of Mohican Indians, Ramapough Lenape Nation, and the Delaware Tribe of Indians. My research expands scholarship on sovereignty by unpacking the concept of a bounded, grounded sovereignty and tying it to communicative practices distributed across dispersed communities. Fluid Indigenous sovereignties, articulated through storytelling, food, language, and cultural revitalization movements, re-establish pre-colonial connections and create new ones between diaspora communities across colonial borders. They are embodied within songs, food, communications, and movement. Ph.D.Includes bibliographical reference