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Articles 1 - 30 of 43
Full-Text Articles in Engineering
The Development Of A Laminated Copolyester Electric Guitar, Addison S. Karnes
The Development Of A Laminated Copolyester Electric Guitar, Addison S. Karnes
Electronic Theses and Dissertations
This thesis is an investigation of the fabrication and assembly methodologies employed in the development of a proof-of-principle prototype electric guitar composed of laminated copolyester. The objective of the project was to develop the processes and procedures to create an optimized physical and visual bond between layers to minimize vibratory dissipation, thus maximizing sustain. A high speed CNC router, abrasive waterjet, laser engraver-cutter, as well as various manual fabrication and assembly methods were investigated in the construction of the guitar prototypes. The lamination processes explored include low-temperature, heat-assisted pressure bonding, solvent and chemical welding, and contact adhesives. The project concluded …
Complementary Layered Learning, Sean Mondesire
Complementary Layered Learning, Sean Mondesire
Electronic Theses and Dissertations
Layered learning is a machine learning paradigm used to develop autonomous robotic-based agents by decomposing a complex task into simpler subtasks and learns each sequentially. Although the paradigm continues to have success in multiple domains, performance can be unexpectedly unsatisfactory. Using Boolean-logic problems and autonomous agent navigation, we show poor performance is due to the learner forgetting how to perform earlier learned subtasks too quickly (favoring plasticity) or having difficulty learning new things (favoring stability). We demonstrate that this imbalance can hinder learning so that task performance is no better than that of a suboptimal learning technique, monolithic learning, which …
Automatic Detection Of Brain Functional Disorder Using Imaging Data, Soumyabrata Dey
Automatic Detection Of Brain Functional Disorder Using Imaging Data, Soumyabrata Dey
Electronic Theses and Dissertations
Recently, Attention Deficit Hyperactive Disorder (ADHD) is getting a lot of attention mainly for two reasons. First, it is one of the most commonly found childhood behavioral disorders. Around 5-10% of the children all over the world are diagnosed with ADHD. Second, the root cause of the problem is still unknown and therefore no biological measure exists to diagnose ADHD. Instead, doctors need to diagnose it based on the clinical symptoms, such as inattention, impulsivity and hyperactivity, which are all subjective. Functional Magnetic Resonance Imaging (fMRI) data has become a popular tool to understand the functioning of the brain such …
Frequency Selective Detection Of Infrared Radiation In Uncooled Optical Nano-Antenna Array, Sushrut Modak
Frequency Selective Detection Of Infrared Radiation In Uncooled Optical Nano-Antenna Array, Sushrut Modak
Electronic Theses and Dissertations
Mid-infrared (mid-IR) detection and imaging over atmospheric transparent 3-5 μm and 8-12 μm bands are increasingly becoming important for various space, defense and civilian applications. Various kinds of microbolometers offer uncooled detection of IR radiation. However, broadband absorption of microbolometers makes them less sensitive to spectrally resolved detection of infrared radiation and the fabrication is also very tedious involving multiple complex lithography steps. In this study, we designed an optical nano-antenna array based detector with narrow frequency band of operation. The structure consists of a two-element antenna array comprised of a perforated metallic hole array coupled with an underneath disk …
Self-Heating Control Of Edge Emitting And Vertical Cavity Surface Emitting Lasers, Yu Zhang
Self-Heating Control Of Edge Emitting And Vertical Cavity Surface Emitting Lasers, Yu Zhang
Electronic Theses and Dissertations
Self-heating leads to temperature rise of laser diode and limits the output power, efficiency and modulation bandwidth due to increased loss and decreased differential gain. The main heat sources in laser diode during continuous wave operation are Joule heating and free carrier absorption loss. To control device self-heating, the epi structure needs to be designed with low electrical resistance and low absorption loss, while the heat flux must spread out of the device efficiently. This dissertation presents the control of self-heating of both edge emitting laser diodes and vertical cavity surface emitting lasers (VCSELs). For the 980nm high power edge …
Distribution Of Laser Induced Heating In Multi-Component Chalcogenide Glass And Its Associated Effects, Laura Sisken
Distribution Of Laser Induced Heating In Multi-Component Chalcogenide Glass And Its Associated Effects, Laura Sisken
Electronic Theses and Dissertations
Chalcogenide glasses are well known to have good transparency into the infrared spectrum. These glasses though tend to have low thresholds as compared to oxide glasses for photo-induced changes and thermally-induced changes. Material modification such as photo-induced darkening, bleaching, refractive index change, densification or expansion, ablation of crystallization have been demonstrated, and are typically induced by a thermal furnace-based heat treatment, an optical source such as a laser, or a combination of photo-thermal interactions. Solely employing laser-based heating has an advantage over a furnace, since one has the potential to be able to spatially modify the materials properties with much …
Highly-Sensitive Stoichiometric Analysis Of Yag Ceramics Using Laser-Induced Breakdown Spectroscopy (Libs), Jahromi, Ali Kazemi
Highly-Sensitive Stoichiometric Analysis Of Yag Ceramics Using Laser-Induced Breakdown Spectroscopy (Libs), Jahromi, Ali Kazemi
Electronic Theses and Dissertations
Transparent ceramics are an important class of optical materials with applications in high-strength windows, radiation detectors and high-power lasers. Despite the many successful developments of the past decades, their challenging fabrication still needs to be perfected to achieve a better consistency in optical quality. In particular, ternary phase materials such as Yttrium Aluminum Garnet (YAG, Y3Al5O12), a long standing high-power laser host, require a precise control of stoichiometry, often beyond the precision of current analytical techniques, in order to reduce scattering losses and the presence of deleterious point defects. This work explores the potential of Laser-Induced Breakdown Spectroscopy (LIBS) for …
Automatic 3d Human Modeling: An Initial Stage Towards 2-Way Inside Interaction In Mixed Reality, Yiyan Xiong
Automatic 3d Human Modeling: An Initial Stage Towards 2-Way Inside Interaction In Mixed Reality, Yiyan Xiong
Electronic Theses and Dissertations
3D human models play an important role in computer graphics applications from a wide range of domains, including education, entertainment, medical care simulation and military training. In many situations, we want the 3D model to have a visual appearance that matches that of a specific living person and to be able to be controlled by that person in a natural manner. Among other uses, this approach supports the notion of human surrogacy, where the virtual counterpart provides a remote presence for the human who controls the virtual character's behavior. In this dissertation, a human modeling pipeline is proposed for the …
High Resolution Time-Resolved Imaging System In The Vacuum Ultraviolet Region, Yuseong Jang
High Resolution Time-Resolved Imaging System In The Vacuum Ultraviolet Region, Yuseong Jang
Electronic Theses and Dissertations
High-power debris-free vacuum ultraviolet (VUV) light sources have applications in several scientific and engineering areas, such as high volume manufacturing lithography and inspection tools in the semiconductor industry, as well as other applications in material processing and photochemistry. For the past decades, the semiconductor industry has been driven by what is called "Moore's Law". The entire semiconductor industry relies on this rule, which requires chip makers to pack transistors more tightly with every new generation of chips, shrinking the size of transistors. The ability to solve roadmap challenges is, at least partly, proportional to our ability to measure them. The …
Functional Scaffolding For Musical Composition: A New Approach In Computer-Assisted Music Composition, Amy K. Hoover
Functional Scaffolding For Musical Composition: A New Approach In Computer-Assisted Music Composition, Amy K. Hoover
Electronic Theses and Dissertations
While it is important for systems intended to enhance musical creativity to define and explore musical ideas conceived by individual users, many limit musical freedom by focusing on maintaining musical structure, thereby impeding the user's freedom to explore his or her individual style. This dissertation presents a comprehensive body of work that introduces a new musical representation that allows users to explore a space of musical rules that are created from their own melodies. This representation, called functional scaffolding for musical composition (FSMC), exploits a simple yet powerful property of multipart compositions: The pattern of notes and rhythms in different …
High Performance Three-Dimensional Display Based On Polymer-Stabilized Blue Phase Liquid Crystal, Yifan Liu
High Performance Three-Dimensional Display Based On Polymer-Stabilized Blue Phase Liquid Crystal, Yifan Liu
Electronic Theses and Dissertations
Autostereoscopic 2D/3D (two-dimension/three-dimension) switchable display has been attracting great interest in research and practical applications for several years. Among different autostereoscopic solutions, direction-multiplexed 3D displays based on microlens array or parallax barrier are viewed as the most promising candidates, due to their compatibility with conventional 2D display technologies. These 2D/3D switchable display system designs rely on fast switching display panels and photonics devices, including adaptive focus microlens array and switchable slit array. Polymer-stabilized blue phase liquid crystal (PS-BPLC) material provides a possible solution to meet the aforementioned fast response time requirement. However, present display and photonic devices based on blue …
Holographic Recording And Applications Of Multiplexed Volume Bragg Gratings In Photo-Thermo-Refractive Glass, Daniel Ott
Holographic Recording And Applications Of Multiplexed Volume Bragg Gratings In Photo-Thermo-Refractive Glass, Daniel Ott
Electronic Theses and Dissertations
Recent developments in holographic recording of volume Bragg gratings (VBGs) in photo-thermo-refractive (PTR) glass have demonstrated their utility as components in high power laser systems for spectral narrowing, transverse mode control, beam combining, and pulse stretching/compression. VBG structures are capable of diffracting incident light into a single diffraction order with high efficiency given the Bragg condition is met. The Bragg condition depends on both the wavelength and angle of the incident light making VBGs useful for filtering and manipulating both the wavelength and angular spectrum of a source. This dissertation expands upon previous research in PTR VBGs by investigating multiplexed …
Intelligent Selection Techniques For Virtual Environments, Jeffrey Cashion
Intelligent Selection Techniques For Virtual Environments, Jeffrey Cashion
Electronic Theses and Dissertations
Selection in 3D games and simulations is a well-studied problem. Many techniques have been created to address many of the typical scenarios a user could experience. For any single scenario with consistent conditions, there is likely a technique which is well suited. If there isn't, then there is an opportunity for one to be created to best suit the expected conditions of that new scenario. It is critical that the user be given an appropriate technique to interact with their environment. Without it, the entire experience is at risk of becoming burdensome and not enjoyable. With all of the different …
Improved Internet Security Protocols Using Cryptographic One-Way Hash Chains, Amerah Alabrah
Improved Internet Security Protocols Using Cryptographic One-Way Hash Chains, Amerah Alabrah
Electronic Theses and Dissertations
In this dissertation, new approaches that utilize the one-way cryptographic hash functions in designing improved network security protocols are investigated. The proposed approaches are designed to be scalable and easy to implement in modern technology. The first contribution explores session cookies with emphasis on the threat of session hijacking attacks resulting from session cookie theft or sniffing. In the proposed scheme, these cookies are replaced by easily computed authentication credentials using Lamport's well-known one-time passwords. The basic idea in this scheme revolves around utilizing sparse caching units, where authentication credentials pertaining to cookies are stored and fetched once needed, thereby, …
Entangled Photon Pairs In Disordered Photonic Lattices, Lane Martin
Entangled Photon Pairs In Disordered Photonic Lattices, Lane Martin
Electronic Theses and Dissertations
Photonic lattices consisting of arrays of evanescently coupled waveguides fabricated with precisely controlled parameters have enabled the study of discrete optical phenomena, both classical and quantum, and the simulation of other physical phenomena governed by the same dynamics. In this dissertation, I have experimentally demonstrated transverse Anderson localization of classical light in arrays with off-diagonal coupling disorder and investigated theoretically and experimentally the propagation of entangled photon pairs through such disordered systems. I discovered a new phenomenon, Anderson co-localization, in which a spatially entangled photon pair in a correlated transversally extended state localizes in the correlation space, though neither photon …
Injection-Locked Vertical Cavity Surface Emitting Lasers (Vcsels) For Optical Arbitrary Waveform Generation, Sharad Bhooplapur
Injection-Locked Vertical Cavity Surface Emitting Lasers (Vcsels) For Optical Arbitrary Waveform Generation, Sharad Bhooplapur
Electronic Theses and Dissertations
Complex optical pulse shapes are typically generated from ultrashort laser pulses by manipulating the optical spectrum of the input pulses. This generates complex but periodic time-domain waveforms. Optical Arbitrary Waveform Generation (OAWG) builds on the techniques of ultrashort pulse-shaping, with the goal of making non-periodic, truly arbitrary optical waveforms. Some applications of OAWG are coherently controlling chemical reactions on a femtosecond time scale, improving the performance of LADAR systems, high-capacity optical telecommunications and ultra wideband signals processing. In this work, an array of Vertical Cavity Surface Emitting Lasers (VCSELs) are used as modulators, by injection-locking each VCSEL to an individual …
Integrated Remote Sensing And Forecasting Of Regional Terrestrial Precipitation With Global Nonlinear And Nonstationary Teleconnection Signals Using Wavelet Analysis, Lee Mullon
Electronic Theses and Dissertations
Global sea surface temperature (SST) anomalies have a demonstrable effect on terrestrial climate dynamics throughout the continental U.S. SST variations have been correlated with greenness (vegetation densities) and precipitation via ocean-atmospheric interactions known as climate teleconnections. Prior research has demonstrated that teleconnections can be used for climate prediction across a wide region at sub-continental scales. Yet these studies tend to have large uncertainties in estimates by utilizing simple linear analyses to examine chaotic teleconnection relationships. Still, non-stationary signals exist, making teleconnection identification difficult at the local scale. Part 1 of this research establishes short-term (10-year), linear and non-stationary teleconnection signals …
Nonlinear Integrated Photonics On Silicon And Gallium Arsenide Substrates, Jichi Ma
Nonlinear Integrated Photonics On Silicon And Gallium Arsenide Substrates, Jichi Ma
Electronic Theses and Dissertations
Silicon photonics is nowadays a mature technology and is on the verge of becoming a blossoming industry. Silicon photonics has also been pursued as a platform for integrated nonlinear optics based on Raman and Kerr effects. In recent years, more futuristic directions have been pursued by various groups. For instance, the realm of silicon photonics has been expanded beyond the well-established near-infrared wavelengths and into the mid-infrared (3 - 5 µm). In this wavelength range, the omnipresent hurdle of nonlinear silicon photonics in the telecommunication band, i.e., nonlinear losses due to two-photon absorption, is inherently nonexistent. With the lack of …
Sketchart: A Pen-Based Tool For Chart Generation And Interaction., Andres Vargas Gonzalez
Sketchart: A Pen-Based Tool For Chart Generation And Interaction., Andres Vargas Gonzalez
Electronic Theses and Dissertations
It has been shown that representing data with the right visualization increases the understanding of qualitative and quantitative information encoded in documents. However, current tools for generating such visualizations involve the use of traditional WIMP techniques, which perhaps makes free interaction and direct manipulation of the content harder. In this thesis, we present a pen-based prototype for data visualization using 10 different types of bar based charts. The prototype lets users sketch a chart and interact with the information once the drawing is identified. The prototype's user interface consists of an area to sketch and touch based elements that will …
Photonic Filtering For Applications In Microwave Generation And Metrology, Marcus Bagnell
Photonic Filtering For Applications In Microwave Generation And Metrology, Marcus Bagnell
Electronic Theses and Dissertations
This work uses the photonic filtering properties of Fabry-Perot etalons to show improvements in the electrical signals created upon photodetection of the optical signal. First, a method of delay measurement is described which uses multi-heterodyne detection to find correlations in white light signals at 20 km of delay to sub millimeter resolution. By filtering incoming white light with a Fabry-Perot etalon, the pseudo periodic signal is suitable for measurement by combining and photodetecting it with an optical frequency comb. In this way, optical data from a large bandwidth can be downconverted and sampled on low frequency electronics. Second, a high …
Visual Analysis Of Extremely Dense Crowded Scenes, Haroon Idrees
Visual Analysis Of Extremely Dense Crowded Scenes, Haroon Idrees
Electronic Theses and Dissertations
Visual analysis of dense crowds is particularly challenging due to large number of individuals, occlusions, clutter, and fewer pixels per person which rarely occur in ordinary surveillance scenarios. This dissertation aims to address these challenges in images and videos of extremely dense crowds containing hundreds to thousands of humans. The goal is to tackle the fundamental problems of counting, detecting and tracking people in such images and videos using visual and contextual cues that are automatically derived from the crowded scenes. For counting in an image of extremely dense crowd, we propose to leverage multiple sources of information to compute …
Multifunctional, Multimaterial Particle Fabrication Via An In-Fiber Fluid Instability, Joshua Kaufman
Multifunctional, Multimaterial Particle Fabrication Via An In-Fiber Fluid Instability, Joshua Kaufman
Electronic Theses and Dissertations
Spherical micro- and nano-particles have found widespread use in many various applications from paint to cosmetics to medicine. Due to the multiplicity of desired particle material(s), structure, size range, and functionality, many approaches exist for generating such particles. Bottom-up methods such as chemical synthesis have a high yield and work with a wide range of materials; however, these processes typically lead to large polydispersity and cannot produce structured particles. Top-down approaches such as microfluidics overcome the polydispersity issue and may produce a few different structures in particles, but at lower rates and only at the micro-scale. A method that can …
Large Area Conformal Infrared Frequency Selective Surfaces, Jeffrey D'Archangel
Large Area Conformal Infrared Frequency Selective Surfaces, Jeffrey D'Archangel
Electronic Theses and Dissertations
Frequency selective surfaces (FSS) were originally developed for electromagnetic filtering applications at microwave frequencies. Electron-beam lithography has enabled the extension of FSS to infrared frequencies; however, these techniques create sample sizes that are seldom appropriate for real world applications due to the size and rigidity of the substrate. A new method of fabricating large area conformal infrared FSS is introduced, which involves releasing miniature FSS arrays from a substrate for implementation in a coating. A selective etching process is proposed and executed to create FSS particles from crossed-dipole and square-loop FSS arrays. When the fill-factor of the particles in the …
Broad Bandwidth, All-Fiber, Thulium-Doped Photonic Crystal Fiber Amplifier For Potential Use In Scaling Ultrashort Pulse Peak Powers, Alex Sincore
Electronic Theses and Dissertations
Fiber based ultrashort pulse laser sources are desirable for many applications; however generating high peak powers in fiber lasers is primarily limited by the onset of nonlinear effects such as self-phase modulation, stimulated Raman scattering, and self-focusing. Increasing the fiber core diameter mitigates the onset of these nonlinear effects, but also allows unwanted higher-order transverse spatial modes to propagate. Both large core diameters and single-mode propagation can be simultaneously attained using photonic crystal fibers. Thulium-doped fiber lasers are attractive for high peak power ultrashort pulse systems. They offer a broad gain bandwidth, capable of amplifying sub-100 femtosecond pulses. The longer …
Laser Filamentation - Beyond Self-Focusing And Plasma Defocusing, Khan Lim
Laser Filamentation - Beyond Self-Focusing And Plasma Defocusing, Khan Lim
Electronic Theses and Dissertations
Laser filamentation is a highly complex and dynamic nonlinear process that is sensitive to many physical parameters. The basic properties that define a filament consist of (i) a narrow, high intensity core that persists for distances much greater than the Rayleigh distance, (ii) a low density plasma channel existing within the filament core, and (iii) a supercontinuum generated over the course of filamentation. However, there remain many questions pertaining to how these basic properties are affected by changes in the conditions in which the filaments are formed; that is the premise of the work presented in this dissertation. To examine …
Multimaterial Fibers In Photonics And Nanotechnology, Guangming Tao
Multimaterial Fibers In Photonics And Nanotechnology, Guangming Tao
Electronic Theses and Dissertations
Recent progress in combing multiple materials with distinct optical, electronic, and thermomechanical properties monolithically in a kilometer-long fiber drawn from a preform offers unique multifunctionality at a low cost. A wide range of unique in-fiber devices have been developed in fiber form-factor using this strategy. Here, I summary my recent results in this nascent field of 'multimaterial fibers'. I will focus on my achievements in producing robust infrared optical fibers and in appropriating optical fiber production technology for applications in nanofabrication. The development of optical components suitable for the infrared (IR) is crucial for applications in this spectral range to …
Remote Sensing With Computational Intelligence Modelling For Monitoring The Ecosystem State And Hydraulic Pattern In A Constructed Wetland, Golam Mohiuddin
Remote Sensing With Computational Intelligence Modelling For Monitoring The Ecosystem State And Hydraulic Pattern In A Constructed Wetland, Golam Mohiuddin
Electronic Theses and Dissertations
Monitoring the heterogeneous aquatic environment such as the Stormwater Treatment Areas (STAs) located at the northeast of the Everglades is extremely important in understanding the land processes of the constructed wetland in its capacity to remove nutrient. Direct monitoring and measurements of ecosystem evolution and changing velocities at every single part of the STA are not always feasible. Integrated remote sensing, monitoring, and modeling technique can be a state-of-the-art tool to estimate the spatial and temporal distributions of flow velocity regimes and ecological functioning in such dynamic aquatic environments. In this presentation, comparison between four computational intelligence models including Extreme …
Techniques For Characterization Of Third Order Optical Nonlinearities, Manuel Ferdinandus
Techniques For Characterization Of Third Order Optical Nonlinearities, Manuel Ferdinandus
Electronic Theses and Dissertations
This dissertation describes the development of novel techniques for characterization of nonlinear properties of materials. The dissertation is divided into two parts, a background and theory section and a technique development section. In the background and theory section we explain the origins of the nonlinear optical response of materials across many different spatial and temporal scales. The mechanisms that we are most interested in are the electronic nuclear and reorientational responses, which occur on the range of sub-femtosecond to several picoseconds. The electronic mechanism is due to the electrons of a material experiencing a non-parabolic potential well due a strong …
A Continuous Hydrologic Model Structure For Applications At Multiple Time Scales, Jonathan Griffen
A Continuous Hydrologic Model Structure For Applications At Multiple Time Scales, Jonathan Griffen
Electronic Theses and Dissertations
There are many different controlling factors on the partitioning of rainfall into runoff. However, the influence of each of these controls varies across different temporal scales. Consequently, numerous water balance models have been developed in the literature for application across various time scales. These models are usually developed for a particular time scale so that the controls with the greatest influence on rainfall partitioning are captured. For example, the SCS curve number method was developed to simulate direct runoff at the event scale; the "abcd" model was developed as a monthly water balance model; and the Budyko model was developed …
Energy Efficient Routing Towards A Mobile Sink Using Virtual Coordinates In A Wireless Sensor Network, Rouhollah Rahmatizadeh
Energy Efficient Routing Towards A Mobile Sink Using Virtual Coordinates In A Wireless Sensor Network, Rouhollah Rahmatizadeh
Electronic Theses and Dissertations
The existence of a coordinate system can often improve the routing in a wireless sensor network. While most coordinate systems correspond to the geometrical or geographical coordinates, in recent years researchers had proposed the use of virtual coordinates. Virtual coordinates depend only on the topology of the network as defined by the connectivity of the nodes, without requiring geographical information. The work in this thesis extends the use of virtual coordinates to scenarios where the wireless sensor network has a mobile sink. One reason to use a mobile sink is to distribute the energy consumption more evenly among the sensor …