LOUIS University of Alabama in Huntsville
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A framework for identifying transit deserts in rural areas with demand-response transit services
Get PDFThe primary objective of this research is to develop a comprehensive framework for identifying transit deserts in rural areas with Demand Response Transit (DRT) services. This framework will focus on marginalized rural areas in Alabama, providing a foundation for better understanding their transportation needs. The research gap regarding transit deserts in rural areas is significant. While the concept of transit deserts has been explored in urban settings, rural areas with DRT services remain largely under-researched. Addressing this gap is vital for establishing equitable access to transit services across rural areas. This research contributes to the existing body of literature in two major ways: This study will develop a metric to identify transit deserts in rural areas, grounded in both socioeconomic and supply factors. Six socioeconomic factors—identified through a repurposed survey—and seven supply factors based on accessibility will be used to calculate transit deserts. This metric will offer a quantitative approach for measuring transit deserts, providing clarity on where transit needs are insufficient. In addition to developing the metric, this research will produce a tool that integrates with ArcGIS via Excel. This tool will enable users to visually map the locations of transit deserts, helping policymakers and transit authorities conduct more effective analyses and make informed decisions regarding rural transit planning
Enhanced suppression of stimulated Brillouin Scattering in high energy fiber lasers through novel chaotic phase modulation
Get PDFStimulated Brillouin scattering (SBS) poses a significant challenge in the development of high-power, single-mode continuous-wave fiber lasers. SBS occurs when the laser intensity is sufficient to generate acoustic vibrations in the fiber, leading to the reflection of light and limiting the maximum achievable power. Spectral broadening of the laser linewidth is a common SBS suppression technique. This thesis presents a novel approach using sine waves phase-modulated by chaotically generated noise to achieve improved SBS suppression. Experimental results demonstrate that this method achieves flatter and broader optical linewidths compared to traditional white noise modulation, even at lower power levels. This approach was successfully tested on a kilowatt-class fiber laser, and its simplicity and ability to be engineered enable unprecedented levels of spectral broadening
A study of the quantum edge extraction technique using bitplane-based quantum boolean image processing algorithm
Get PDFQuantum image processing (QIMP) uses quantum information processing to create and work with quantum images. Due to the inherent properties of quantum computation, QIMP technologies have the potential to surpass their classical computing equivalents in terms of computing speed and storage requirements. In this thesis, we investigated quantum image edge detection, which is a fundamental tool used in image processing for feature detection and extraction. Quantum edge detection can exploit quantum mechanics\u27 superposition and entanglement properties to perform operations simultaneously on all pixels and accelerate the process. To this end, we adopted the bitplane based framework of Quantum Boolean Image Processing that utilizes the computational basis states, with the advantage of having low computational cost and low impact on quantum measurements. We conducted a comprehensive and in-depth study of the Quantum Boolean Edge Extraction method. More specifically, we decomposed an image into bitplanes and then converted the most significant bitplane from the classical state to the quantum state. Subsequently, we applied the quantum algorithm to extract edges. We assessed the effectiveness of edge extraction by using different bitplanes. Besides, we compared the results of edge extraction using classical implementations with quantum implementations. We also conducted a detailed analysis of the quantum implementation complexity in terms of the number of quantum logic gates. Finally, we presented the results of running the quantum edge extraction algorithm on both ideal and noisy simulator backends of various quantum computing platforms, including the IBM Qiskit, Google Cirq, as well as AQT (Alpine Quantum Technologies) backend. These simulation results demonstrated the robustness of the quantum edge extraction algorithm
A novel method for time-based synchronization of acquired force and motion data
Get PDFEnhancing the performance of flapping wing micro air vehicles hinges upon a thorough comprehension of the intricate interplay between wing kinematics and resulting forces. This understanding necessitates a method of synchronization capable of establishing a precise correlation of wing motion and force generation. The objective of this project is to develop a time-based synchronization method using existing hardware in the ATOM lab. Algorithms were developed to control the Vicon motion-tracking system and the ATI force sensor to achieve the synchronization of acquired data. Experimental testing was conducted to validate the algorithms and system architecture. Results from testing revealed a time lag delay, equivalent to the acquisition time of the force transducer between the two measurements. This delay indicates that synchronization was not achieved. Further investigations suggest that the operating system and the data acquisition board were limited in executing resource intensive input/output bound tasks to support synchronization
An empirical study of the relationship between automation and aircrew accident performance in high performance aircraft operating in the U.S. naval shipboard
Get PDFThe research described in this dissertation was an empirical study of cockpit automation and aircrew accident performance in high performance aircraft. The data set consisted of 3,249 accident records released by the U.S. Naval Safety Center and publicly available information for high performance aircraft based aboard U.S. aircraft carriers between the years of 1980 and 2013. Five conclusions resulted from this study. The first result was a demonstration that through statistical analysis, it is possible to assess if different aircraft over a prolonged period of time have been exposed to a common operating environment. The second result was that while accident rate is the traditional method of measuring accident performance, the costs and/or fatalities associated with accidents may be more useful measurements. The third result was the use of current taxonomies of category, type and level of automation present in systems was sufficient for correlation of automation attributes to measures of human accident performance. Additionally, it was discovered and recommended that the list of automation categories be expanded to include one for human life support systems. The fourth conclusion from this study was that correlation did exist between certain configurations of cockpit automation and accident performance. The fifth conclusion is the observation of a potential connection between group identity fusion and fatality rate for accidents involving automated cockpit systems
Coronal magnetic field extrapolation and topological analysis of multi-scale magnetic structures for solar eruptions
Get PDFSolar eruptions are manifestations of strong solar activities which occur in multiple scales and vary significantly in observations. It has also been increasingly realized that some scenarios initially proposed for relatively large-scale eruptions may persist down to much smaller/finer scales, largely owing to increasingly high-resolution observations of the Sun. However, confirming the coherent magnetic structures on the Sun remains challenging due to the lack of direct coronal magnetic field measurement. This dissertation mainly focuses on the topological analysis of multi-scale magnetic structures embodied in different solar eruptions with available observations. It is achieved by reconstructing the 3D coronal magnetic field through one unique nonlinear force-free field (NLFFF) extrapolation method, the CESE-MHD-NLFFF code, modified and tested for nonuniform embedded magnetograms. The performance of the modified code is evaluated extensively through a series of test runs based on different input magnetograms and grid constructions. Two selected solar flare eruptions are investigated to make a connection between the magnetic flux ropes (MFRs) on the Sun and their interplanetary counterparts quantitatively. For event 1, a coherent MFR before the flare eruption is identified combining the multi-wavelength observations and the NLFFF extrapolation results. The total magnetic reconnection flux during the eruption amounts to ~ 1021 Mx, which is measured by analyzing the associated flare ribbons via remote-sensing observations. It is significantly larger than the flux in the identified pre-eruptive MFR (1019 ~ 1020 Mx). For event 2, there is no pre-eruptive MFR found with the same criteria as event 1. In both events, the total magnetic reconnection flux (in the order of ~1021 Mx) agrees with the corresponding magnetic flux contents of the MFRs after the eruptions from the in situ modeling results. To study the fine-scale magnetic structures, the modified CESE-MHD-NLFFF code is applied to a flare precursor event with nonuniform embedded magnetograms from the Goode Solar Telescope (GST) and the Solar Dynamics Observatory (SDO). By comparing the extrapolation results with the simultaneous SDO and high-resolution GST observations, the magnetic field lines originating from the precursor brightening regions show a more consistent configuration with observations. The resolved fine-scale magnetic structures exhibit low-lying sheared arcades characteristic of a plausible configuration for precursor magnetic reconnection before the main flare onset. In addition, a recurrent solar jet event is also studied by employing two sets of embedded magnetograms from GST and SDO. We find small closed loops surrounded by open field lines in two runs, which indicates a scenario of interchange reconnection leading to the occurrence of the jets. These quantitative investigations contribute to understanding the important role of magnetic reconnection in shaping the topological features seen in observations and shed light on the underlying physical mechanisms driving the solar eruptions
Benefits of quadratically tapered flexures for MEMS resonators and gyroscopes
Get PDFAn investigation into the benefits of quadratically tapered flexures for MEMS resonators and gyroscopes is performed and compared to the traditional non-tapered flexure design. Quadratically tapered flexures exhibit constant strain along the outer edge of the flexure whereas non-tapered flexures have significant stress concentration near the base of the flexure. The investigation considers peak stress, thermoelastic damping (TED), nonlinearity, and sensitivity to manufacturing variations. The impact of inside corner fillets on peak stress, TED, and resonant frequency is also investigated. Five new anti-phase lever mechanism (APLM) configurations for resonators and gyroscopes are designed and analyzed using CoventorWare 10. Fabrication experiment results are presented for an array of resonator designs to substantiate the FEA findings. Quadratically tapered flexures are found to reduce stress and thermoelastic damping while maintaining similar sensitivity to manufacturing variations, but at the cost of a slight increase in nonlinearity
A new, intuitive method for the design and analysis of multi-pass cavities
Get PDFThis dissertation develops a new analytical approach for designing and analyzing multi-pass cavities like the Herriott cell employing the graphical yӯ diagram approach. The new technique can be deployed in spectroscopy absorption detection, femtoseconds laser cavities, or any off -axis spherical mirror interferometers applications. Such a system can be uniquely designed and evaluated by entering a few parameters that define the required physics for the cell, the packaging size limits for the system and the probe beam size, plus two user selected parameters. The existing design method, developed by Herriott, is discussed and then the yӯ diagram method is presented and applied, showing several design solutions that meet the spectroscopic absorption system requirements. The adaptability of the yӯ diagram approach is then shown, presenting several design solutions with mirrors of arbitrary curvatures, and a new approach of rapid calculations of 3rd order astigmatism, the dominant aberration in these systems. This dissertation also employs the yӯ diagram of Gaussian beams to illustrate detailed design parameters of gas spectrometer sensor and develops an enhanced Gaussian beam decomposition technique that could be used for physical optics, and diffraction analysis for this system or any other optical system. These methods enable rapid, intuitive layout and creating of simple equations yielding results match very well with physical optics ray tracing software
