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Machine learning-assisted multiscale simulation and design optimization of composite jackets under low-velocity impacts
No full textThis research presents the development of a data-driven machine learning-assisted approach to simulate and optimize the design of composite materials subjected to low-velocity impacts. It focuses on a specific type of hybrid composite comprised of fiberglass and Kevlar fabrics stitched with Kevlar threads. The study begins by creating a multiscale finite element simulation for the composite under a low-velocity impact, which operates across three scales: microscale, mesoscale, and macroscale. This simulation accepts various inputs, such as different layer configurations and orientations, and provides impact outputs including maximum load and energy absorption capacity and displacement at failure.
Python and MATLAB scripts manage the simulation, automating data generation to create a large dataset for analyzing the composite under low-velocity impacts at both the mesoscale and macroscale levels. This data then trains artificial neural networks (ANNs) at each scale, which are coupled to form a multiscale machine learning-assisted simulation. The mesoscale ANN uses homogenized mechanical properties (HMPs) from the microscale model of the composite layers to predict mesoscale HMPs where a combination of layers and stitching threads are considered in a mesoscale representative volume element (RVE). The macroscale ANN then uses the mesoscale HMPs to produce the composite\u27s impact response, including maximum force and energy absorption capacity and displacement at failure.
Finally, the multiscale ANN system is integrated with a particle swarm optimization (PSO) algorithm to explore the design space and find the optimal composite configuration for specific impact conditions and constraints. All simulation results and predictions from the multiscale ANN are validated against experimental data on composites subjected to low-velocity impacts. The multiscale ANN approach introduced in this study is flexible and can be applied to other complex materials and structures where several variables across different scales influence the results. This study shows the efficiency of the introduced approach specifically for the optimization process where several possible combinations of the design space need to be evaluated to find the best combination for a given set of constraints
A Grounded Theory Investigation of Basic Psychological Needs Theory as a Framework for Effective Mental Health Referrals in Collegiate Sport
Get PDFUsing a grounded theory approach, this study explored collegiate athletes’ mental health referral experiences and identified mechanisms explaining those experiences based upon perceptions of psychological need fulfillment and thwarting according to Basic Psychological Needs Theory (BPNT). Interviews were conducted with a purposive, maximum variation sample of 14 current and former collegiate athletes who were referred to mental health services by support personnel or other athletes. Analyses yielded three overarching theoretical categories/properties: pre-referral factors, proactive and reactive referral conversations, and referral outcomes. Referral is often understood as an isolated conversation in which athletes are provided mental health resources in response to a crisis. Challenging this notion, the present study showed that proactive referral as a preventative approach, as well as intentional understanding athletes’ pre-referral experiences, were central to supporting athletes’ relationship with their mental health. Generally, referral experiences that resulted in helping athletes disconnect their mental health concerns from understandings of their self-worth, and ultimately pursue mental health services with hope for recovery, were linked to psychological need satisfaction throughout the referral process (e.g., autonomously choosing mental health services, relating to the referrer through a similar experience, mastering skills for pursuing therapy). Yet, in cases of positive referral experiences, some athletes re-internalized mental health stigma upon re-engaging with unsupportive sport and familial environments. Need thwarting amid the referral conversation was generally associated with poorer outcomes, in addition to cultural environments that deterred help-seeking. Together, the data suggest BPNT is a promising framework for effective referral guidance, though psychological needs are met uniquely for each athlete based upon their characteristics and context
A Portable, Digital Nucleic Acid Amplification Test for Use at the Point of Care
No full textNucleic acid tests are key tools for the detection and diagnosis of many diseases. In many cases, the amplification of nucleic acids is required to reach a detectable level. Although nucleic acid tests have great success, there is a need to make nucleic acid amplification tests more accessible to a point-of-care (POC) setting for diagnosis, prognosis, and monitoring of infectious diseases. Traditionally, these tests are performed through bulk Polymerase Chain Reaction (PCR) and are monitored in real time with a change in fluorescence intensity. With these bulk testing methods, only a qualitative or semi-quantitative result is possible. For more exact quantification of results, digital nucleic acid amplification tests can be utilized. Although exact quantification is a benefit for monitoring and prognosis for infectious diseases, these tests are performed in large laboratory settings that can be controlled. As a result, there are limitations for applying the technology to POC settings due to three main aspects: compartmentalization, amplification, and detection.
There are two main categories for compartmentalization of a bulk reaction solution for digital tests, microwells and droplets. With microwell arrays, the individual reaction portions are the same in size leading to simple quantification of results. However, the analysis is limited to only the number of microwells used in the assay. In contrast, any number of droplets can be used for more accurate results, but it is difficult to ensure all droplets are monodisperse. To provide a simple and portable system for droplet generation, we have developed the vibrating sharp-tip capillary. With the vibrating sharp-tip capillary device simple, tunable, on-demand, and monodisperse droplet generation is possible with a large range of droplet sizes from a single device. In addition, the large range of droplet sizes possible allows for a high dynamic range assay. Because of the development of the vibrating sharp-tip capillary, the compartmentalization of nucleic acids for digital assays is possible at POC.
The next aspect to address is the amplification of nucleic acids. Traditionally, nucleic acid amplification tests have been performed with PCR, however there are several isothermal amplification techniques available for POC applications. Loop-mediated isothermal amplification (LAMP) is considered the standard for isothermal amplification of nucleic acids. With LAMP, loop structures are formed with the use of 4-6 primer sequences. When the loop structures form, amplification of the nucleic acid target occurs. We have incorporated LAMP with the vibrating sharp-tip capillary device for a high dynamic range (~2 to 6000 copies/µL) digital droplet loop-mediated isothermal amplification (ddLAMP) system. As LAMP is isothermal, only a simple heat source is needed for implementation at POC. However, the method still utilizes fluorescence detection, indicating further work was needed to adapt the detection method to POC.
To further improve the ddLAMP assay, cellphone-based detection was investigated. The LAMP reaction is unique among isothermal amplification techniques, due to the formation of a precipitate byproduct, Magnesium Pyrophosphate. We found that this precipitate is visible under a bright-field microscope, with a direct match to the fluorescence images. Furthermore, when a simple microscope lens was attached to a cellphone, the precipitate was visible in the center of the droplets. The presence of the precipitate was more noticeable with large droplet diameters larger than approximately 250 μm. The precipitate became less distinguishable with smaller droplet diameters. As a result, the minimum droplet diameter usable with current method is at approximately 100 μm, although droplet diameters at approximately 70 μm were detected in some instances. When the same droplet samples were analyzed using fluorescence and bright field cellphone detection, a similar dynamic range was determined. For fluorescence detection, the dynamic range was determined to be approximately 3 to 650 copies of DNA target per microliter. In comparison, the dynamic range for cellphone detection was determined to be 2 to 700 copies of DNA target per microliter. With further improvements, the dynamic range could be pushed even further allowing for a high dynamic range ddLAMP system for use at POC.
Although LAMP is isothermal and requires only a simple heat source, the temperature required is relatively high (approximately 65 °C). As a result, some softer isothermal amplification techniques have been developed such as Recombinase Polymerase Amplification (RPA). In this method, the sample is held at a constant low temperature (approximately 40 °C) for 20 to 25 minutes, compared to 2.5 hours for PCR or 1 hour for LAMP. As a result, RPA could greatly reduce the assay time in POC settings, allowing for more immediate treatment. However, there are some issues to overcome for implementation of digital RPA at POC. RPA is a chemically initiated process and can begin at room temperature with the addition of the Magnesium Acetate coenzyme. This limits the capabilities of sample loading and compartmentalization for digital analysis. To overcome the compartmentalization issue, a vibrating sharp-tip theta capillary device was developed. With the theta capillary device, two separate solutions are introduced through the individual channels of the device. As the droplets form at the tip of the device, the two solutions mix to form the overall reaction solution.
In addition to RPA, the theta capillary device has the potential to implement many other methods of digital analysis, such as digital Enzyme-Linked Immunosorbent Assay (ELISA). With a sandwich-based digital ELISA, magnetic beads would be treated with a capture antibody, the target, and a detection antibody prior to loading into one channel of the theta capillary device. The substrate solution would then be loaded into the other channel of theta capillary device, allowing for digital detection of the target. In addition, the reaction of Catalase and Hydrogen Peroxide to form oxygen gas could be used in conjunction with the theta capillary. The Catalase enzyme could be used to tag the target nucleic acid sequence or protein and distributed in solution loaded into one channel. A Hydrogen Peroxide solution could then be added to the second channel. As the two solutions mix, oxygen gas is formed and trapped within the droplets. It would also be a benefit to enclose the droplet reservoirs, as under current conditions, the droplet reservoirs are open which can lead to spillage of mineral oil
THREE ESSAYS ON EXTERNALITIES OF ENERGY AND AGRICULTURAL PRODUCTION
Get PDFThis dissertation consists of three essays exploring the externalities that arise from energy production and development in a developing country, Nigeria, and agricultural production in a developed nation, the United States (US). The research examines the benefits of energy development in terms of its impact on local wealth and the associated costs, including the health effects on communities living near energy production sites. Additionally, the dissertation analyzes the opportunity costs of policies aimed at preventing the relocation of nutrients, particularly nitrogen fertilizers, within the agricultural sector and their impact on the producer and consumer surplus.
The first essay examines the impacts of power plants on nearby residents’ well-being using six rounds of Nigeria Demographic and Health Surveys (NDHS) and comprehensive power plant operations data in Nigeria. I find that households within 10 km of operational power plants have gained a higher asset-based wealth score index by 0.20-2.71 than those located 10-20 km away. These wealth increases are most pronounced for households near larger-capacity plants and those with members in manual labor and sales/services occupations, likely driven by heightened demand during power plants\u27 construction and operational phases. Additionally, the likelihood of electricity access increases with power plant operations. The results highlight the potential role of increased economic opportunities and electricity access in driving wealth gains through power plant construction and operations and offer policy insights into aligning economic advancement initiatives with the national electricity development plan for Nigeria and other developing countries.
In the second essay, the dissertation addresses the rare quantitative evidence of the negative externalities of power plants in developing countries by analyzing their impact on infant and child mortality using NDHS data and detailed power plant operation records. Infants born within a 5-25 km radius of active power plants experience approximately 0.027 more deaths during their first month than those born before power plants became operational or near non-operational power plants. Pollutants generated by non-renewables are likely the cause as the mortality rates are more significant by 0.010 for those near power plants fueled by non-renewable energy sources. In contrast, the impact of renewable energy-fueled power plants is insignificant. These results further justify electricity generation by renewable energy sources in addressing Nigeria and other developing countries’ pressing energy deficits with health and carbon-related benefits.
Finally, the third essay investigates the interdependence of nutrient runoff from agricultural production in three major US watersheds. It quantifies Nitrogen loading leakage across these watersheds using an integrated assessment model (IAM), which combines economic partial equilibrium commodity market formulation, spatial land use representation, and a process-based Soil and Water Assessment Tool (SWAT). I also assess consumer and producer surplus losses from decreased commodity supply and higher prices when nutrient delivery to select coastal ecosystems is restricted. Reducing agricultural N loading in the Gulf of Mexico by 45% (a) increases loading in the Chesapeake Bay and Western Lake Erie by 4.2% and 5.5%, respectively, and (b) results in annual surplus losses of 6.95 billion with and without restrictions on leakage to the Chesapeake Bay and Lake Erie, respectively
Machine Learning Based Intrusion Detection Framework for CAN Bus Vulnerabilities in Modern Vehicles
Get PDFThe Controller Area Network (CAN) bus is a crucial communication backbone in modern vehicles, connecting various Electronic Control Units (ECUs). However, inherent design weaknesses such as the lack of encryption and authentication make CAN networks vulnerable to cyber-attacks, including spoofing, Denial of Service (DoS), and fuzzing attacks. This thesis thoroughly evaluates these vulnerabilities and the limitations of existing security frameworks like Message Authentication Codes (MACs) and encryption, advocating for the adoption of Intrusion Detection Systems (IDS) as a more practical solution for CAN bus security. The proposed IDS leverages advanced machine learning techniques to accurately detect intrusions, even under complex attack configurations. In the first phase of this research, a One-Dimensional Convolutional Neural Network (1D-CNN) IDS model was developed and evaluated on both the robust ORNL ROAD and the HCRL dataset. While existing models achieve near-perfect accuracy on straightforward attack datasets like HCRL, this thesis demonstrates the limitations of these datasets in representing real-world threats. Testing on ROAD, which includes stealthier and more diverse attack scenarios, the 1D-CNN model struggled with detecting attacks with intricate patterns, hence the need for more robust IDS architecture. To address this, a hybrid model combining 1D-CNN with Bidirectional Long Short-Term Memory (BiLSTM) was designed to capture both spatial and temporal features in CAN traffic. This hybrid approach significantly improved detection accuracy and reduced the false positive rate, particularly for stealthy attacks such as targeted ID manipulations. Key enhancements include class weighting to handle imbalanced data, systematic hyperparameter tuning, and dropout regularization to prevent overfitting. Extensive testing on the ROAD dataset resulted in a model accuracy of 99.64%, demonstrating the hybrid IDS’s capacity to detect even the most sophisticated CAN bus attacks efficiently. This thesis contributes to vehicular network security by establishing a benchmark for IDS performance on high-fidelity CAN datasets. The findings emphasize the importance of hybrid architectures in enhancing IDS capabilities and underscore the necessity for realistic datasets in assessing IDS robustness in real-world applications
Ownership and Development of Rare Earth Elements and Critical Minerals in Mine Drainage in West Virginia
Get PDFThis Article argues in support of recent legislation which clarifies legal title to potentially valuable substances derived from the treatment of mine drainage in West Virginia’s waters. West Virginia University has been researching the commercial viability of extracting rare earth elements and other critical minerals from coal mine drainage and coal mine waste. If successful, the research may foster a new industry and provide citizens and wildlife with cleaner water flowing in West Virginia’s rivers and streams. The West Virginia Legislature was concerned that ownership disputes and litigation might harm the development of this potential resource and enacted statutory provisions clarifying ownership regarding the minerals which are dissolved in the state’s waters. This Article provides the language used in the newly enacted statutory provisions. This Article summarizes relevant common law principles including riparian rights, contract and leasing rights, abandonment, and the rule of capture. The Article also considers existing federal and state statutory duties concerning mining and its adverse effects on the environment. The Article discusses potential challenges to the legislation including takings and the impairment of contracts. The Article argues in support of the legislation and its role in fulfilling state’s legal duties to encourage the removal of pollution from West Virginia’s rivers and streams
Interactions Between Myeloid Cells and Neutrophil Extracellular Traps in Pancreatic Ductal Adenocarcinoma
Get PDFThe 5-year-survival rate for pancreatic ductal adenocarcinoma (PDAC) is only 12% due in part to a lack of therapeutic strategies that target the pathophysiology of the disease. The only known curative therapy is surgical resection of the PDAC tumor, but only 20% of patients are eligible at the time of presentation. To improve outcomes for patients, new therapeutic options are needed. The PDAC tumor microenvironment (TME) is uniquely fibrotic and hypoxic, which is in part driven by the immune cell composition in the TME. Myeloid cells are a prominent immune infiltrate within the PDAC TME, so these cells have been an important research focus when considering therapeutic targets. Despite research into myeloid populations in PDAC, targeting these cells clinically has proven challenging with only modest improvements in outcomes. Thus, better strategies are needed to understand these highly plastic immune cells. Further, a better understanding of how myeloid cells can be influenced by other innate immune cells, particularly neutrophils, is needed since these two cell populations are known to interact in settings outside of cancer. The central hypothesis for this dissertation is that different myeloid cell subpopulations can differentially influence patient outcomes in PDAC. Further, we suggest that neutrophil extracellular traps (NETs), a process through which activated neutrophils released their intracellular contents into the circulation or extracellular space that has been implicated in PDAC pathogenesis, may play a role in regulating these myeloid cell populations. Herein, we utilize single nuclear assay for transpose accessible chromatin sequencing (snATAC-Seq) of frozen PDAC tissues to show that dendritic cell infiltrates improve outcomes in PDAC patients. Further, we explore monocyte recruitment in the presence and absence of NETs to implicate NETs in the regulation of monocyte infiltration into the PDAC TME. The present work provides evidence of an important role for myeloid subpopulations in the PDAC TME and implicates NETs as an important modifier for myeloid cell recruitment
Through the Keyhole
Get PDFThrough the Keyhole derives inspiration from the lyrical styles of Tchaikovsky and Rachmaninoff. The transformational form of the piece follows an organic growth process leading up to a true climax. The piece stops, yet it does not end, leaving the listener to feel incomplete. Two melodic themes shape the piece alongside timbral developments. The harmony helps to portray the emotional journey of the piece, changing slightly throughout