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Full-Text Articles in Engineering
The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco
The Subject Librarian Newsletter, Engineering And Computer Science, Fall 2017, Buenaventura "Ven" Basco
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Picosecond Yb-Doped Fiber Amplifier, Weibin Zhu
Picosecond Yb-Doped Fiber Amplifier, Weibin Zhu
Electronic Theses and Dissertations
Due to its versatility, rare earth doped fiber amplifier (RDFA) has attracted a lot of researchers worldwide in recent years. Depends on different kinds of rare earth ion, RDFA can be categorized into neodymium doped fiber amplifier (NDFA), erbium doped fiber amplifier (EDFA), thulium doped fiber amplifier (TDFA), and so forth. Among many kinds of RDFA, the ytterbium doped fiber amplifier (YDFA) has received even more interest, especially in high power application, mainly because of its broad gain bandwidth and high conversion efficiency which are due to its relatively simple electronic structure. The purpose of this research is to study …
A Multiagent Q-Learning-Based Restoration Algorithm For Resilient Distribution System Operation, Jungseok Hong
A Multiagent Q-Learning-Based Restoration Algorithm For Resilient Distribution System Operation, Jungseok Hong
Electronic Theses and Dissertations
Natural disasters, human errors, and technical issues have caused disastrous blackouts to power systems and resulted in enormous economic losses. Moreover, distributed energy resources have been integrated into distribution systems, which bring extra uncertainty and challenges to system restoration. Therefore, the restoration of power distribution systems requires more efficient and effective methods to provide resilient operation. In the literature, using Q-learning and multiagent system (MAS) to restore power systems has the limitation in real system application, without considering power system operation constraints. In order to adapt to system condition changes quickly, a restoration algorithm using Q-learning and MAS, together with …
The Effect Of Morphology On Reflectance In Silicon Nanowires Grown By Electroless Etching, Victor Velez
The Effect Of Morphology On Reflectance In Silicon Nanowires Grown By Electroless Etching, Victor Velez
Electronic Theses and Dissertations
The strong light trapping properties of Silicon Nanowires have attracted much interest in the past few years for the conversion of sun energy into conventional electricity. Studies have been completed for many researchers to reduce the cost of fabrication and reflectance of solar light in these nanostructures to make a cheaper and more efficient solar cell technology by using less equipment for fabrication and employing different materials and solution concentrations. Silver, a conducting and stable metal is used these days as a precursor to react with silicon and then form the nanowires. Its adequate selection of solution concentration for a …
Wearable Passive Wireless Mems Respiration Sensor, Sina Moradian
Wearable Passive Wireless Mems Respiration Sensor, Sina Moradian
Electronic Theses and Dissertations
In this study a passive sensor that wirelessly monitors the profile of the human respiratory system is presented. The sensor was designed to be wearable, weighs less than 10 grams and is durable. The sensor is made of a RF piezoelectric MEMS resonator and an ultra-high frequency antenna made of a thin metal film formed on a flexible substrate . The resonance frequency of the TPoS resonator shifts as a function of condensation and evaporation of water vapor on the surface of the resonator and changes in resonator's temperature. These parameters change in each in response to inspiration and expiration …
Design And Simulation Of Device Failure Models For Electrostatic Discharge (Esd) Event, Meng Miao
Design And Simulation Of Device Failure Models For Electrostatic Discharge (Esd) Event, Meng Miao
Electronic Theses and Dissertations
In this dissertation, the research mainly focused on discussing ESD failure event simulation and ESD modeling, seeking solutions for ESD issues by simulating ESD event and predict possible ESD reliability problem in IC design. The research involves failure phenomenon caused by ESD/ EOS stress, mainly on the thermal failure due to inevitable self-heating during an ESD stress. Standard Complementary Metal-Oxide-Semiconductor (CMOS) process and high voltage Doublediffusion Metal-Oxide-Semiconductor (DMOS) process are used for design of experiment. A multi-function test platform High Power Pulse Instrument (HPPI) is used for ESD event evaluation and device characterization. SPICE-like software ADICE is for back-end simulation. …
Ultra-Efficient Cascaded Buck-Boost Converter, Anirudh Ashok Pise
Ultra-Efficient Cascaded Buck-Boost Converter, Anirudh Ashok Pise
Electronic Theses and Dissertations
This thesis presents various techniques to achieve ultra-high-efficiency for Cascaded-Buck-Boost converter. A rigorous loss model with component non linearity is developed and validated experimentally. An adaptive-switching-frequency control is discussed to optimize weighted efficiency. Some soft-switching techniques are discussed. A low-profile planar-nanocrystalline inductor is developed and various design aspects of core and copper design are discussed. Finite-element-method is used to examine and visualize the inductor design. By implementing the above, a peak efficiency of over 99.2 % is achieved with a power density of 6 kW/L and a maximum profile height of 7 mm is reported. This converter finds many applications …
Development Of An Adaptive Restoration Tool For A Self-Healing Smart Grid, Amir Golshani
Development Of An Adaptive Restoration Tool For A Self-Healing Smart Grid, Amir Golshani
Electronic Theses and Dissertations
Large power outages become more commonplace due to the increase in both frequency and strength of natural disasters and cyber-attacks. The outages and blackouts cost American industries and business billions of dollars and jeopardize the lives of hospital patients. The losses can be greatly reduced with a fast, reliable and flexible restoration tool. Fast recovery and successfully adapting to extreme events are critical to build a resilient, and ultimately self-healing power grid. This dissertation is aimed to tackle the challenging task of developing an adaptive restoration decision support system (RDSS). The RDSS determines restoration actions both in planning and real-time …
Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger
Thermal And Waveguide Optimization Of Broad Area Quantum Cascade Laser Performance, Matthew Suttinger
Electronic Theses and Dissertations
Quantum Cascade Lasers are a novel source of coherent infrared light, unique in their tunability over the mid-infrared and terahertz range of frequencies. Advances in bandgap engineering and semiconductor processing techniques in recent years have led to the development of highly efficient quantum cascade lasers capable of room temperature operation. Recent work has demonstrated power scaling with broad area quantum cascade lasers by increasing active region width beyond the standard ~10 ?m. Taking into account thermal effects caused by driving a device with electrical power, an experimentally fitted model is developed to predict the optical power output in both pulsed …
Photothermal Lensing In Mid-Infrared Materials, Justin Cook
Photothermal Lensing In Mid-Infrared Materials, Justin Cook
Electronic Theses and Dissertations
A thorough understanding of laser-materials interactions is crucial when designing and building optical systems. An ideal test method would probe both the thermal and optical properties simultaneously for materials under large optical loads where detrimental thermal effects emerge. An interesting class of materials are those used for infrared wavelengths due to their wide spectral transmission windows and large optical nonlinearities. Since coherent sources spanning the mid-wave and long-wave infrared wavelength regions have only become widely available in the past decade, data regarding their thermal and optical responses is lacking in literature. Photothermal Lensing (PTL) technique is an attractive method for …
High Dynamic Range Display Systems, Ruidong Zhu
High Dynamic Range Display Systems, Ruidong Zhu
Electronic Theses and Dissertations
High contrast ratio (CR) enables a display system to faithfully reproduce the real objects. However, achieving high contrast, especially high ambient contrast (ACR), is a challenging task. In this dissertation, two display systems with high CR are discussed: high ACR augmented reality (AR) display and high dynamic range (HDR) display. For an AR display, we improved its ACR by incorporating a tunable transmittance liquid crystal (LC) film. The film has high tunable transmittance range, fast response time, and is fail-safe. To reduce the weight and size of a display system, we proposed a functional reflective polarizer, which can also help …
An All-Against-One Game Approach For The Multi-Player Pursuit-Evasion Problem, Shahriar Talebi
An All-Against-One Game Approach For The Multi-Player Pursuit-Evasion Problem, Shahriar Talebi
Electronic Theses and Dissertations
The traditional pursuit-evasion game considers a situation where one pursuer tries to capture an evader, while the evader is trying to escape. A more general formulation of this problem is to consider multiple pursuers trying to capture one evader. This general multi-pursuer one-evader problem can also be used to model a system of systems in which one of the subsystems decides to dissent (evade) from the others while the others (the pursuer subsystems) try to pursue a strategy to prevent it from doing so. An important challenge in analyzing these types of problems is to develop strategies for the pursuers …
Method For Real-Time Signal Selection For Passive Coherent Location Systems, Nicholas Johnson
Method For Real-Time Signal Selection For Passive Coherent Location Systems, Nicholas Johnson
Electronic Theses and Dissertations
Passive coherent location (PCL) systems use signals of opportunity to perform traditional radar detection, targeting, and tracking functions. Traditionally these signals include FM radio, digital TV, GSM, and GPS because of their availability in most urban environments. A benefit of having an abundance of signals is the ability to choose which of those best meet the desired system intentions. For example, one may want to choose a digital TV signal over an FM radio signal due to its range resolution characteristics. This work presents a novel algorithm for characterizing commercial signals for use in a PCL system. By analyzing each …
Learning Kernel-Based Approximate Isometries, Mahlagha Sedghi
Learning Kernel-Based Approximate Isometries, Mahlagha Sedghi
Electronic Theses and Dissertations
The increasing availability of public datasets offers an inexperienced opportunity to conduct data-driven studies. Metric Multi-Dimensional Scaling aims to find a low-dimensional embedding of the data, preserving the pairwise dissimilarities amongst the data points in the original space. Along with the visualizability, this dimensionality reduction plays a pivotal role in analyzing and disclosing the hidden structures in the data. This work introduces Sparse Kernel-based Least Squares Multi-Dimensional Scaling approach for exploratory data analysis and, when desirable, data visualization. We assume our embedding map belongs to a Reproducing Kernel Hilbert Space of vector-valued functions which allows for embeddings of previously unseen …
Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei
Novel Photonic Resonance Arrangements Using Non-Hermitian Exceptional Points, Hossein Hodaei
Electronic Theses and Dissertations
In recent years, non-Hermitian degeneracies also known as exceptional points (EPs) have emerged as a new paradigm for engineering the response of optical systems. EPs can appear in a wide class of open non-Hermitian configurations. Among different types of non-conservative photonic systems, parity-time (PT) symmetric arrangements are of particular interest since they provide an excellent platform to explore the physics of exceptional points. In this work, the intriguing properties of exceptional points are utilized to address two of the long standing challenges in the field of integrated photonics- enforcing single mode lasing in intrinsically multimode cavities and enhancing the sensitivity …
On Distributed Estimation For Resource Constrained Wireless Sensor Networks, Alireza Sani
On Distributed Estimation For Resource Constrained Wireless Sensor Networks, Alireza Sani
Electronic Theses and Dissertations
We study Distributed Estimation (DES) problem, where several agents observe a noisy version of an underlying unknown physical phenomena (which is not directly observable), and transmit a compressed version of their observations to a Fusion Center (FC), where collective data is fused to reconstruct the unknown. One of the most important applications of Wireless Sensor Networks (WSNs) is performing DES in a field to estimate an unknown signal source. In a WSN battery powered geographically distributed tiny sensors are tasked with collecting data from the field. Each sensor locally processes its noisy observation (local processing can include compression, dimension reduction, …
Understanding Images And Videos Using Context, Gonzalo Vaca Castano
Understanding Images And Videos Using Context, Gonzalo Vaca Castano
Electronic Theses and Dissertations
In computer vision, context refers to any information that may influence how visual media are understood. Traditionally, researchers have studied the influence of several sources of context in relation to the object detection problem in images. In this dissertation, we present a multifaceted review of the problem of context. Context is analyzed as a source of improvement in the object detection problem, not only in images but also in videos. In the case of images, we also investigate the influence of the semantic context, determined by objects, relationships, locations, and global composition, to achieve a general understanding of the image …
Reliable Spectrum Hole Detection In Spectrum-Heterogeneous Mobile Cognitive Radio Networks Via Sequential Bayesian Non-Parametric Clustering, Alireza Zaeemzadeh
Reliable Spectrum Hole Detection In Spectrum-Heterogeneous Mobile Cognitive Radio Networks Via Sequential Bayesian Non-Parametric Clustering, Alireza Zaeemzadeh
Electronic Theses and Dissertations
In this work, the problem of detecting radio spectrum opportunities in spectrum-heterogeneous cognitive radio networks is addressed. Spectrum opportunities are the frequency channels that are underutilized by the primary licensed users. Thus, by enabling the unlicensed users to detect and utilize them, we can improve the efficiency, reliability, and the flexibility of the radio spectrum usage. The main objective of this work is to discover the spectrum opportunities in time, space, and frequency domains, by proposing a low-cost and practical framework. Spectrum-heterogeneous networks are the networks in which different sensors experience different spectrum opportunities. Thus, the sensing data from sensors …
Enhanced Ablation By Femtosecond And Nanoseond Pulses, Haley Kerrigan
Enhanced Ablation By Femtosecond And Nanoseond Pulses, Haley Kerrigan
Electronic Theses and Dissertations
Laser ablation of GaAs by a combination of femtosecond and nanosecond pulses is investigated as a means of enhancing material removal by a femtosecond pulse in the filamentation intensity regime. We demonstrate for the first time increased ablation of GaAs by ultrafast laser pulse plasmas augmented by nanosecond pulse radiation from a secondary laser. Material removal during laser ablation is a complex process that occurs via multiple mechanisms over several timescales. Due to different pulse durations, ablation by femtosecond and nanosecond pulses are dominated by different mechanisms. Ablation can be enhanced by optimally combining a femtosecond and nanosecond pulse in …
Enhancement Of Antenna Array Performance Using Reconfigurable Slot-Ring Antennas And Integrated Filter/Antennas, Tianjiao Li
Enhancement Of Antenna Array Performance Using Reconfigurable Slot-Ring Antennas And Integrated Filter/Antennas, Tianjiao Li
Electronic Theses and Dissertations
As modern communication system technology develops, the demand for devices with smaller size, higher efficiency, and more functionality has increased dramatically. In addition, highly integrated RF-front-end modules with a reduced footprint and less transition loss between cascaded devices are desirable in most advanced wireless communication systems. Antenna arrays are widely used in wireless communication systems due to their high directivity and beam steering capability. Moreover, antenna arrays are preferred in mobile communication systems for diversity reception to reduce signal fading effects. In order to meet the various requirements of rapidly developing wireless communication systems, low cost, compact, multifunctional integrated antenna …
Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken
Laser-Induced Crystallization Mechanisms In Chalcogenide Glass Materials For Advanced Optical Functionality, Laura Sisken
Electronic Theses and Dissertations
Glass-ceramics (GC) are promising candidates for gradient refractive index (GRIN) optics. These multi-phase, composite materials also exhibit improved physical properties as compared to the parent base glass resulting from the formation of a secondary crystalline phase(s). Nanocrystal phase formation in a multi-component chalcogenide glass (ChG), (GeSe2-3As2Se3)(1-x)-(PbSe)x glass where x = 0-40 has been investigated, and the role of the starting material morphology has been correlated to the resulting composite's optical properties including refractive index, transmission, dispersion, and thermo-optic coefficient. Optical property evolution was related to the type and amount of the crystal phases formed, since through control of the local …
Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen
Advanced Liquid Crystal Displays With Supreme Image Qualities, Haiwei Chen
Electronic Theses and Dissertations
Several metrics are commonly used to evaluate the performance of display devices. In this dissertation, we analyze three key parameters: fast response time, wide color gamut, and high contrast ratio, which affect the final perceived image quality. Firstly, we investigate how response time affects the motion blur, and then discover the 2-ms rule. With advanced low-viscosity materials, new operation modes, and backlight modulation technique, liquid crystal displays (LCDs) with an unnoticeable image blur can be realized. Its performance is comparable to an impulse-type display, like cathode ray tube (CRT). Next, we propose two novel backlight configurations to improve an LCD's …
Design, Simulation And Characterization Of Novel Electrostatic Discharge Protection Devices And Circuits In Advanced Silicon Technologies, Wei Liang
Electronic Theses and Dissertations
Electrostatic Discharge (ESD) has been one of the major reliability concerns in the advanced silicon technologies and it becomes more important with technology scaling. It has been reported that more than 35% of the failures in integrated circuits (ICs) are ESD induced. ESD event is a phenomenon that a finite amount of charges transfer between two objects with different potential in a quite short time. Such event contains a large energy and the ICs without proper ESD protection could be destroyed easily, so ESD protection solutions are essential to semiconductor industry. ESD protection design consists of on-chip and off-chip ESD …
Precision Metrology Of Laser Plasmas In The Xuv Band, John Szilagyi
Precision Metrology Of Laser Plasmas In The Xuv Band, John Szilagyi
Electronic Theses and Dissertations
The XUV band, a region of light spanning the wavelength range of 5 - 200 nm, is located between the Ultraviolet and X-ray regions of the electromagnetic spectrum. It is further divided into a 100 - 200 nm region called the Vacuum Ultraviolet (VUV), and a 5 – 100 nm region called the Extreme Ultraviolet (EUV). Applications of this light have been slow to develop due to the lack of suitable sources, efficient optics, and sensitive detectors. Recently, many industries such as the semiconductor manufacturing industry, medical surgery, micromachining, microscopy, and spectroscopy have begun to benefit from the short wavelengths …
Generation Of High-Flux Attosecond Pulses And Towards Attosecond-Attosecond Pump-Probe Experiments, Yang Wang
Generation Of High-Flux Attosecond Pulses And Towards Attosecond-Attosecond Pump-Probe Experiments, Yang Wang
Electronic Theses and Dissertations
At present, the energy of a single isolated attosecond pulse is limited to nanojoule levels. As a result, an intense femtosecond pulse has always been used in combination with a weak attosecond pulse in time-resolved experiments. To reach the goal of conducting true attosecond pump-attosecond probe experiments, a high flux laser source has been developed that can potentially deliver microjoule level isolated attosecond pulses in the 50 eV range, and a unique experimental end station has been fabricated and implemented that can provide precision control of the attosecond-attosecond pump-probe pulses. In order to scale up the attosecond flux, a unique …
Design Of A Hydrogen-Filled Hollow-Core Fiber Raman Laser, Yangyang Qin
Design Of A Hydrogen-Filled Hollow-Core Fiber Raman Laser, Yangyang Qin
Electronic Theses and Dissertations
The purpose of this study is to investigate the design of a Raman fiber laser based on a molecule hydrogen-filled hollow-core fiber with non-touching single ring of capillaries structure. O-hydrogen vibrational frequency shift of 4155 cm-1 and rotational frequency shift of 587 cm-1 were employed to generate Raman scattering from a 1064nm pump source. A thorough exploration was made to show how all Raman fiber laser components made up: gas chamber, hollow-core fibers, windows. The whole process of chamber design, modification and fabrication were demonstrated. Besides, two kinds of anti-resonant hollow-core fibers were studied and tested. The transmission and loss …
System For Metal Coated Fiber Fabrication, Da Zhang
System For Metal Coated Fiber Fabrication, Da Zhang
Electronic Theses and Dissertations
For many specific applications, such as sensors, aerospace, chemical industry, deep-well oil-field industry, metal-coated fiber shows strong abilities to satisfy people's requirement. With in-line coating technology, we are able to coat Aluminum on the fibers. Using electromagnetic induction, we can easily heat an electrically conducting thing such as a metal with the eddy current. This process is defined as Induction heating. And we will melt the Aluminum by this induction heating during drawing the fibers on the tower. Introduce the fiber tower system. The drawing process of in-line technology is formed of the following steps: Position, Melting, Forming into fibers, …
Ldmos Power Transistor Design And Evaluation Using 2d And 3d Device Simulation, Aiman Salih
Ldmos Power Transistor Design And Evaluation Using 2d And 3d Device Simulation, Aiman Salih
Electronic Theses and Dissertations
The benefit of the super-junction (SJ) technique and the use of a floating P layer for low voltage (30 V) laterally double-diffused metal oxide semiconductor (LDMOS) transistors are investigated in this thesis using Sentaurus TCAD simulation software. Optimizations to the SJ LDMOS were attempted such as adding a buffer layer to the device, but simulation and theoretical evidence point out that the benefits of the SJ technique are marginal at the 30 V application. A replacement for the SJ technique was sought, the floating P structure proved to be a good solution at the low voltage range due to its …
Multi-Transit Echo Suppression For Passive Wireless Surface Acoustic Wave Sensors Using 3rd Harmonic Unidirectional Transducers And Walsh-Hadamard-Like Reflectors, Luis Manuel Rodriguez Cordoves
Multi-Transit Echo Suppression For Passive Wireless Surface Acoustic Wave Sensors Using 3rd Harmonic Unidirectional Transducers And Walsh-Hadamard-Like Reflectors, Luis Manuel Rodriguez Cordoves
Electronic Theses and Dissertations
A passive wireless surface acoustic wave sensor of a delay-line type is composed of an antenna, a transducer that converts the EM signal into a surface acoustic wave, and a set of acoustic reflectors that reflect the incoming signal back out through the antenna. A cavity forms between the transducer and the reflectors, trapping energy and causing multiple unwanted echoes. The work in this dissertation aims to reduce the unwanted echoes so that only the main transit signal is left--the signal of interest with sensor information. The contributions of this dissertation include reflective delay-line device response in the form of …
Evaluation Of The Hurricane Imaging Radiometer (Hirad) Brightness Temperatures, Saleem Sahawneh
Evaluation Of The Hurricane Imaging Radiometer (Hirad) Brightness Temperatures, Saleem Sahawneh
Electronic Theses and Dissertations
The Hurricane Imaging Radiometer (HIRAD) is an experimental, airborne, microwave remote sensor that was developed to measure hurricane surface wind speed and rain rate, and thereby, provide data for scientific research and for the next generation operational hurricane surveillance. The object of this dissertation is to develop objective procedures and techniques that can be used to evaluate and characterize the HIRAD brightness temperature (Tb) image product provided by NASA MSFC. First, the approach that was developed for geolocation (latitude and longitude) accuracy determination of HIRAD image pixels is presented. Using statistical estimation theory, high-contrast HIRAD imagery are compared with high …