136879 research outputs found
Sort by
"Trust to Us, the Union Men of the South": The 1866 Southern Loyalist Convention and the Fight for Reconstruction
No full textIn 1866, unconditional Unionists of the South, who had remained loyal to the United States during its civil war, convened in Philadelphia to express their displeasure with President Andrew Johnson. In their view, Johnson���s willful inaction enabled traitors rather than Unionists to continue dominating Southern politics in the aftermath of the war. If the Union defeated the Confederacy but its supporters remained in power, Unionists��� staunch devotion to the Union was rendered pointless. The 1866 Southern Loyalist Convention was the culmination of years of political struggles. Scholarly literature on Southern Unionists is extensive, yet historians have overlooked the significance of this convention. This thesis argues that the convention utilized a narrative of suffering that Southern Unionists employed consistently throughout the Civil War and Reconstruction. In various pamphlets published early in the crisis, Southern Unionists voiced their disapproval of secession and had articulated their perspectives on national affairs. By concentrating those disparate voices in a single location, the Southern Loyalist Convention amplified long standing whispers of Unionist dissatisfaction. Collectively, these broadsheets pointed to deep divisions among Unionists, generally involving disagreements about African American enfranchisement. Despite the internal divisions that ultimately prevented them from forming a powerful Unionist coalition, Southern Unionists were consistent in a few key ways. They insisted upon their undying support for the Union, demanded the implementation of their agenda, and constructed a powerful narrative of their own suffering. Their mutual misery, in fact, became the foundation upon which Unionists built relationships with each other at this convention. This thesis considers how the 1866 Convention contributed to a post-war narrative that historians have labeled the ���Won Cause��� memory of the war
Design & Manufacture of Additive Manufactured Polymer-Metal Interfaces
No full textThis research investigates the design and manufacture of additively manufactured polymer-metal interfaces while correlating their processing, structure, properties, and performance (PSPP). Our primary goal is to tailor interface design and manufacture to effectively withstand tensile, shear, and combined loading, while fulfilling the constraints of avoiding adhesives or fasteners between the components. To achieve this goal, this study employs mechanical interlocking between polymer and metal surfaces (at a specific size-scale) that includes repeated geometry features (unit-cells) additively manufactured onto the metal surface, and the polymer additively ���infilled��� onto them. The geometrical designs were tailored taking into consideration the advantages and limitations of ���PBF-LB��� for the metal printing (316L stainless-steel), and ���MEX-TRB��� for the polymer printing (PCABS). The study includes the evaluation of various factors affecting the interface ���quality���, including unit-cell shape/size/distribution designs and their implications for polymer filling vs. load capability, the effect of manufacturing process parameters on the interface, and their impact on stress distribution and eventually performance under various loading scenarios. FEA simulations were employed to tailor designs and to parametrically predict the stress-based performance of the interfaces; insights into stress distributions, load capacity and critical points were obtained. Finally, candidate interface designs were additively manufactured, and their performance analyzed under various loading conditions. Altogether, this research strives to facilitate the use of polymer-metal interfaces within additive manufactured components
Colonial Calamities: The Politics of U.S. Disaster Relief and Economic Development in Puerto Rico, 1898-1979
No full textWhen Hurricanes Maria and Fiona battered Puerto Rico in 2017 and 2022, it reopened public conversations about Puerto Rico���s colonial status. With thousands out of electricity, displaced from their homes, and ruined economically, then- and only then- did U.S. policymakers debate the appropriate humanitarian response. In addition, the disaster relief aid overseen by the Federal Emergency Management Agency (FEMA) provided only temporary solutions but did nothing to address the ongoing structural issues of Puerto Rico. This type of response was not a new phenomenon. It was just the latest chapter in a century-long history of United States disaster relief operations that continually reinforced Puerto Rico���s colonial status.
This dissertation Colonial Calamities: The Politics of U.S. Disaster Relief in Puerto Rico, 1898-1979, is the first to explore the history of American disaster relief in Puerto Rico from the period 1898-1979. Disasters provide a window to reveal how structures of power determined who ���deserved��� aid and what conditions were attached to it. I argue that after disasters, the relief policies undertaken by U.S. government institutions were justifications to strengthen influence in the region and actually made Puerto Ricans more vulnerable to disasters. The American military, Red Cross, and colonial administrators prioritized short-term mitigation strategies that served U.S. strategic and economic interests. In this way the American colonial government constructed and maintained Puerto Rican vulnerability to disasters and the vagueness of status as subjects/citizens. American policymakers perpetuated the idea that if Puerto Ricans were poor and vulnerable to disasters, it could not have anything to do with the United States or colonialism. However, policymakers also thought that if Puerto Rican poverty and vulnerability to disasters was caused by Puerto Ricans themselves, then the U.S. and only the U.S. could help them. Together, these ideas inscribed Puerto Ricans as inferior, borderline citizens, while at the same time rejecting them as completely alien. To combat these positions and policies, Puerto Ricans developed local networks to promote solidarity and conduct disaster relief without relying on American agencies. This strategy proved important during the latter part of the twentieth century with the increasing effects of climate change causing more frequent disasters
The Effects of Culturally Tailored Agricultural Literacy Curriculum Among Latino Youth Behavior
No full textAgriculture and nutrition are tightly intertwined as each relies heavily on the other to support the Nation���s food system and the consumers it feeds. Unfortunately, the urbanization of our communities has triggered a divide between farmers and their consumers. This is made evident by the general population lacking an inadequate level of agricultural literacy. Partnered with this decline, an insidious health problem, childhood obesity, has increased in America���s youth. It is important to recognize that there is a higher prevalence of this health disparity among the Hispanic population. Through the lens of the social cognitive theory, the researchers aimed to assess the impact of culturally relevant agricultural literacy lessons have on Latino youths��� agricultural literacy levels and nutrition attitudes and behavior scores. The objectives of this study were achieved by implementing two interventions, the comparison and treatment, to youth after-school and summer programs located in Central and South Texas. The comparison group received the standardized agricultural literacy curriculum from the National Agricultural Literacy Matrix. The treatment group received the culturally tailored version of the curriculum. The pre and posttest data were analyzed by t-tests and repeated measures ANOVA. Regardless of intervention, the agricultural literacy levels of youth increased from pre to posttest which provides researchers with evidence of the positive impact of youth engaging with nutrition based, agricultural literacy curriculum. The youth who engaged with the culturally relevant agricultural literacy curriculum had a positive gain in their nutrition attitudes and behavior scores. Conversely, the comparison group did not have significant change in their nutrition scores. The novelty of this research provides valuable insight to scholars in the agricultural literacy field as it underscores the importance of providing a space for youth to connect their cultural background and experiences while interacting with lessons that highlight the relationship of the agricultural industry and nutrition
Vision-Language Models: The Overlooked Role of Synonyms
No full textIn the past few years, contrastively pre-trained Vision-Language Models (VLMs) such as CLIP, have significantly propelled advancements in multimodal applications. Pre-trained on internet scale images and captions VLMs learn to associate relevant text and images, making them key to downstream applications such as visual chatbots and text-to-image generation diffusion models. However, there has been limited analysis of these models��� pre-training datasets, primarily due to the challenges posed by their large scale. Moreover, given that these datasets lack human annotation, determining the presence of specific visual concepts within them poses a significant challenge.
We address this challenge by using a Large Language Model and count the pre-training texts that contain synonyms of any given visual concept. Contrary to popular belief we discover that these pre-training datasets exhibit a long-tailed concept distribution, resulting in biased performance in VLMs.
Next we propose a novel prompting strategy that leverages synonyms to improve the performance of VLMs for zero-shot recognition. Instead of prompting VLMs using original class names, we use the most frequent synonyms found in the pre-training texts. Finally we propose a novel light-weight retrieval augmented strategy, that achieves a new state-of-the-art for the zero-shot recognition
Electric Vehicle-Induced Grid Impact Analysis and Its Minimization
No full textElectric vehicles are a major component of the clean energy transition. With significant technology improvement and government policies, EVs have increased to 10 million globally. A major bottleneck to accommodate the projected EVs is the development of an affordable and convenient charging infrastructure without needing long waiting times or long-distance travel for charging. As EV chargers draw power from the utility grid, adding the EV charging load impacts the utility grid significantly.
This thesis investigates the impact of EV charging load on three vital grid-performance indicators (voltage profile, load demand curve, and harmonic profile) and develops solutions to minimize them. Firstly, the power electronic circuitry and control algorithms are studied to identify a grid-connected EV load���s power/energy requirements and harmonic profile. Moreover, considering the inter-dependency of voltage profile and power demand, these two parameters are investigated together.
An IEEE 33-bus system is considered, and the actual load data of Qatar���s utility grid is used to define it. A novel two-step EV distribution algorithm has been developed, which helps estimate the 24-hour EV hosting capacity of the network without any intermediate line sections. Furthermore, the impact of the unavailability of DC fast chargers and level-2 chargers (located in parking lots) on EV hosting capacity is investigated to observe whether domestic chargers can address this shortfall.
Renewable-based distributed generators (DG) are optimally placed in the grid using an optimization algorithm to improve the voltage profile and EV hosting capacity. The constraints to this optimization problem reflect the real-world challenges and discourage any transformer or line feeder upgrade. This strategy, known as the non-wire alternative approach, reflects the modular and active solution-based approach of extending the grid performance. The results are assessed and compared with the pre-DG results regarding voltage profile, EV hosting capacity improvement, and peak-shifting phenomenon.
As both the EV charging current and DG injected current contain harmonics, the grid voltage contaminates and thereby deteriorates the power quality of the network. The impact of this deterioration on the grid must be quantified and compared with the actual distribution network. To analyze the overall impact, EVs and DGs are modeled as harmonic sources and added to the utility grid. This modifies the existing harmonic profile of the grid (due to original harmonic loads). Conventional methods of load-side filtering will be ineffective when the penetration levels of these components increase. To address this concern, a novel distributed filtering algorithm is developed, which analyzes the harmonic profile of the entire grid to determine the optimal location of active filters and their power rating. Post-filter placement, the distribution network becomes IEEE 519-2014 compliant
Integrated Techno-Economic and Life-Cycle Assessment of Subsurface Energy-Storage Technologies for Renewable Energy
No full textThe Electric Reliability Council of Texas (ERCOT) has encountered significant renewable energy losses, known as curtailments, due to the fluctuating nature of wind and solar energy, which strains the electric grid. Although energy storage technologies have the potential to alleviate this issue by managing the energy supply, the lack of efficient methods and understanding of their impact has limited their integration into the electric grid. This thesis aims to provide an integrated
techno-economic and life-cycle assessment of two emerging storage technologies, namely subsurface hydrogen (H���) storage and synthetic geothermal storage, to determine the optimal storing option based on estimated efficiency, levelized cost, and greenhouse gas (GHG) emissions. Various phases were analyzed for H��� storage, including H��� production through electrolysis, compression, pumping, subsurface storage, withdrawal, and power generation through a fuel cell. Geothermal storage phases included water heating through an electric-powered hot water/steam
boiler or concentrated solar power (CSP), pumping, storage in geological porous media, withdrawal, and power generation through steam turbines. The monthly averages of ERCOT���s curtailed energy from 2017 to 2021 were used in this study and projected for the next 5 years. Additionally, a reservoir simulation model was utilized to determine the withdrawal efficiency of the geothermal storage. Results showed that around 32-49% of curtailed energy can be recovered through subsurface H��� storage at a minimal levelized cost of 31-50/MWh. Synthetic geothermal storage exhibited higher life-cycle annual emissions and energy consumption, compared to subsurface H��� storage. Results suggest that subsurface H��� storage holds more promise for mitigating renewable energy curtailments
Hardware Approaches for Enabling Multi-Channel Multinuclear MRI/MRS
No full textThis dissertation addresses the challenges faced in exploring X-nuclear possibilities in magnetic resonance imaging and spectroscopy. While proton-based studies are common, the interest in other X-nuclei has grown rapidly. However, limited support from existing MR systems and the challenges in designing multinuclear RF coils hinder these studies. This dissertation proposes a multinuclear RF coil setup and implements two system modification approaches to overcome these challenges.
In X-nuclear studies, the use of double-tuned or multi-tuned RF coils is crucial for examining multiple nuclei without adjusting the setup. This work introduces a three-frequency volume transmit and array receive RF coil setup. The volume transmit coils include a 1H birdcage coil and a double-tuned 2H and 23Na saddle coil, designed to operate individually. A broadband decoupled four-channel receive array is inserted, allowing simultaneous signal reception from all three nuclei. This setup is evaluated through parallel imaging at 1H, 2H, and 23Na frequencies, offering a potential solution for triple-tuned X-nuclear RF coils.
Expanding MR scanners to multinuclear array receiving capability is also explored. This dissertation presents a hardware phase correction solution for receive-only frequency translation, addressing phase incoherence caused by different frequencies between transmit and receive. The proposed hardware utilizes passive phase detectors, a direct digital synthesizer (DDS), and an Arduino microcontroller to automatically correct the received signal phase during the scan and eliminates the need for storing individual echoes or FIDs and performing retrospective phase correction.
Furthermore, the dissertation introduces a cost-effective multinuclear add-on system for traditional MR scanners, enabling simultaneous multinuclear experiments. This system includes multiple transmit and receive mixing channels and a four-channel flexible Local Oscillator (LO) source. By interfacing with the spectrometer, the scanner can transmit and receive at different frequencies simultaneously, reducing experiment time. The results demonstrate simultaneous multinuclear transmit and receive capabilities with 2H and 23Na gradient echo images and interleaved transmit and simultaneous receive ability for 1H, 2H, and 23Na FIDs, showing comparable signal-to-noise ratio performance as the single-frequency operation
Advanced Techniques of Image Dehazing and Object Detection in Hazy Environments
No full textIntelligent Transportation Systems (ITS) represent the future of smart city transportation, heavily reliant on computer vision for tasks such as object detection and recognition. However, real-world scenarios often introduce challenges such as haze, which can significantly impact the effectiveness of computer vision systems. This dissertation addresses these challenges through the proposal of innovative methods aimed at enhancing object detection in hazy environments.
Firstly, a novel Multiple Linear Regression Haze-removal model based on Dark Channel Prior (MLDCP) is introduced. This model achieves state-of-the-art dehazing performance by optimizing the estimation of transmission maps and atmospheric light. Additionally, pre-dehazing test images using MLDCP significantly enhance object detection accuracy by improving visibility. Secondly, a Synthetic Haze Generation Model is proposed to augment existing image datasets. By introducing synthetic haze, this model enables the training of object detectors robust to hazy conditions. This approach enhances the generalizability of object detection models, enabling them to perform effectively in diverse environmental conditions. Furthermore, depth estimation is addressed using a Dilated Fully Convolutional Neural Network. By incorporating dilated convolution, this model achieves depth estimation with reduced computational costs while maintaining high accuracy. This enhancement contributes to a more comprehensive understanding of the geometric relations within a scene, further improving object detection performance. Lastly, a Local Dehazing algorithm based on Dark Channel Prior is proposed. Leveraging object coordinates obtained from object detection tasks, this algorithm optimizes dehazing over specific regions, leading to improved detection accuracy on targeted objects.
Collectively, these contributions advance the field of computer vision for intelligent transportation systems and related applications in hazy environments. By addressing the challenges posed by haze, these methods offer promising solutions for improving the reliability and effectiveness of ITS in real-world settings
John Bickham field notebook: AK12501-AK13000.pdf
No full textBound book, each page corresponds to a karyotype slide data.Data pages for AK13001-AK13500 corresponding to unique identifiers of specimens/samples examined for biological research. Specimens are primarily housed at Texas A&M University; Biodiverstiy Research and Teaching Collection