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Articles 61 - 90 of 269
Full-Text Articles in Electrical and Computer Engineering
Analysis Of Evolutionary Algorithms In The Control Of Path Planning Problems, Pavlos Androulakakis
Analysis Of Evolutionary Algorithms In The Control Of Path Planning Problems, Pavlos Androulakakis
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The purpose of this thesis is to examine the ability of evolutionary algorithms (EAs) to develop near optimal solutions to three different path planning control problems. First, we begin by examining the evolution of an open-loop controller for the turn-circle intercept problem. We then extend the evolutionary methodology to develop a solution to the closedloop Dubins Vehicle problem. Finally, we attempt to evolve a closed-loop solution to the turn constrained pursuit evasion problem. For each of the presented problems, a custom controller representation is used. The goal of using custom controller representations (as opposed to more standard techniques such as …
Leveraging 3d Models For Sar-Based Navigation In Gps-Denied Environments, Zachary A. Reid
Leveraging 3d Models For Sar-Based Navigation In Gps-Denied Environments, Zachary A. Reid
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This thesis considers the use of synthetic aperture radar (SAR) to provide absolute platform position information in scenarios where GPS signals may be degraded, jammed, or spoofed. Two algorithms are presented, and both leverage known 3D ground structure in an area of interest, e.g. provided by LIDAR data, to provide georeferenced position information to airborne SAR platforms. The first approach is based on the wide-aperture layover properties of elevated reflectors, while the second approach is based on correlating backprojected imagery with digital elevation imagery. Both of these approaches constitute the system we have designated: SARNAV. Building on 3D backprojection, localization …
Switching Neural Network Systems For Nonlinear Tracking, Manoj Ghimire
Switching Neural Network Systems For Nonlinear Tracking, Manoj Ghimire
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In this thesis, we consider the problem of tracking in complex nonlinear dynamical systems. While the Kalman filter is known to be the mean-squared error optimal tracker under linear dynamics and linear measurements, more sophisticated models and algorithms are required for complex dynamics. Here, we consider switching systems where the dynamical properties vary (''switch modes") over time. For example, the dynamics of a vehicle may switch as it transitions from interstate to urban conditions, human speech dynamics switch as speakers change, and stock market dynamics switch with discrete news events. In this work, we use mode-dependent neural networks to capture …
A Simulation Method For Studying Effects Of Site-Specific Clutter On Sar-Gmti Performance, Marcus James Campbell
A Simulation Method For Studying Effects Of Site-Specific Clutter On Sar-Gmti Performance, Marcus James Campbell
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Synthetic aperture radar (SAR) is an invaluable tool for detection of ground moving targets when combined with processing techniques of ground moving target indication (GMTI). This work investigates a simulation methodology for studying impact of site-specific ground clutter on SAR-GMTI performance. A terrain model is proposed and is based on digital terrain elevation data (DTED) and national land-use land-cover data (NLCD) as provided by the US Geological Survey. The proposed physical optics simulation method capitalizes on high-fidelity digital target models in combination with the proposed terrain model. SAR phase history is generated for a moving commercial target in situ of …
A Robust Low Power Static Random Access Memory Cell Design, A. V. Rama Raju Pusapati
A Robust Low Power Static Random Access Memory Cell Design, A. V. Rama Raju Pusapati
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Stability of a Static Random Access Memory (SRAM) cell is an important factor when considering an SRAM cell for any application. The Static Noise Margin (SNM) of a cell, which determines the stability, varies under different operating conditions. Based on the performance of three existing SRAM cell designs, 6T, 8T and 10T, a 10 Transistor SRAM cell is proposed which has good stability and has the advantage of reduced read power when compared to 6T and 8T SRAM cells. The proposed 10T SRAM cell has a single-ended read circuit which improves SNM over the 6T cell. The proposed 10T cell …
Impact Of Near-Field-To-Far-Field Transformation On Sar Images Formed In An Indoor Non-Anechoic Environment, Jacob D. Compaleo
Impact Of Near-Field-To-Far-Field Transformation On Sar Images Formed In An Indoor Non-Anechoic Environment, Jacob D. Compaleo
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This work investigates the impact of the near-field-to-far-field transformation (NFFFT) algorithm on phase history measurement collections completed in the Sensors and Signals Exploitation Laboratory (SSEL). SSEL is an indoor non-anechoic environ- ment that is at risk to some measurement interferences such as multiple bounces. Complete 360-degree phase history measurements of scale model aircraft are con- ducted at varying range values within the near-field limit. These measurements are calibrated with the Mie series scattering solution for a sphere. After calibration, the measurements are transformed using the NFFFT, with radar cross-section (RCS) estimated. RCS of the transformed data is compared with the …
Display And Analysis Of Tomographic Reconstructions Of Multiple Synthetic Aperture Ladar (Sal) Images, Bassirou Seck
Display And Analysis Of Tomographic Reconstructions Of Multiple Synthetic Aperture Ladar (Sal) Images, Bassirou Seck
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Synthetic aperture ladar (SAL) is similar to synthetic aperture radar (SAR) in that it can create range/cross-range slant plane images of the illuminated scatters; however, SAL has wavelengths 10,000x smaller than SAR enabling a relatively narrow real aperture, diffraction limited beam widths. The relatively narrow real aperture resolutions allow for multiple slant planes to be created for a single target with reasonable range/aperture combinations. These multiple slant planes can be projected into a single slant plane projections (as in SAR). It can also be displayed as a 3-D image with asymmetric resolutions, diffraction limited in the dimension orthogonal to the …
Steady-State And Small-Signal Modeling Of A-Source Converter, Agasthya Ayachit
Steady-State And Small-Signal Modeling Of A-Source Converter, Agasthya Ayachit
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As the trend towards vehicle electrification, renewable energy, smart systems is increasing, the key enabling technology such as power electronics are becoming ever more important. Power electronics is the vital component of many applications in automotive, computer, data-centers, medical, aerospace, communication, green-energy, and manufacturing sectors. Major advancements in high efficiency, high power density, high voltage conversion ratio, and fast dynamic response power-electronic converters is evident both in research and industry, particularly at the topology level. A major contribution of this dissertation is the analysis, design, development, and dynamic modeling of a novel impedance-source topology termed as A-source converter, which potentially …
Characterization And Design Of Voltage-Mode Controlled Full-Bridge Dc/Dc Converter With Current Limit, Nathaniel R. Smith
Characterization And Design Of Voltage-Mode Controlled Full-Bridge Dc/Dc Converter With Current Limit, Nathaniel R. Smith
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Advancements in Direct Current (DC) electrical power systems have enabled new functionality in many, varied applications. Discrete power semiconductor devices are increasing in efficiency, switching frequency, and power density, resulting in greater usage of DC power management and distribution methods, including DC/DC conversion. DC distribution lacks inherent capability to safely and effectively break fault current, particularly in mobile solutions, where larger and slower electromechanical switching devices are not optimal or feasible. One solution is to design a low-energy breaking point into a switching power supply. Simpler converter designs, with a lower number of switching devices, have been modeled and can …
Effects Of The Kinematic Model On Forward-Model Based Spotlight Sar Ecm, David T. Pyles
Effects Of The Kinematic Model On Forward-Model Based Spotlight Sar Ecm, David T. Pyles
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Spotlight synthetic aperture radar (SAR) provides a high-resolution remote image formation capability for airborne platforms. SAR image formation processes exploit the amplitude, time, and frequency shifts that occur in the transmitted waveform due to electromagnetic propagation and scattering. These shifts are predictable through the SAR forward model which is dependent on the waveform parameters and emitter flight path. The approach to develop an electronic countermeasure (ECM) system that is founded on the SAR forward model implies that the ECM system should alter the radar's waveform in a manner that produces the same amplitude, time, and frequency shifts that a real …
Design Of An 8-Bit Successive Approximation Pipelined Analog To Digital Converter (Sap-Adc) In 90 Nm Cmos, Vivek Kotti
Design Of An 8-Bit Successive Approximation Pipelined Analog To Digital Converter (Sap-Adc) In 90 Nm Cmos, Vivek Kotti
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Analog to Digital Converters bridge the gap between physical world and digital signal processing. Most times analog signals received from the real world needs to be amplified and converted to digital to impart various signal enhancements to the received signal. The digital signal is much suitable to operate on with less noise and well defined logic levels when compared to continuously varying analog signal. Communication systems demand ever-increasing bandwidth which unfortunately has been a huge limitation for present day ADCs. Hence, an architecture which combines the accuracy of a SAR -ADC with the concept of pipelining to increase the bandwidth …
Sv-Means: A Fast One-Class Support Vector Machine-Based Level Set Estimator, Anne M. Pavy
Sv-Means: A Fast One-Class Support Vector Machine-Based Level Set Estimator, Anne M. Pavy
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In this dissertation, a novel algorithm, SV-Means, is developed motivated by the many functions needed to perform radar waveform classification in an evolving, contested environment. Important functions include the ability to: reject classes not in the library, provide confidence in the classification decision, adapt the decision boundary on-the-fly, discover new classes, and quickly add new classes to the library. The SV-Means approach addresses these functions by providing a fast algorithm that can be used for anomaly detection, density estimation, open set classification, and clustering, within a Bayesian generative framework. The SV-Means algorithm extends the quantile one-class support vector machine (q-OCSVM) …
An Optimization Strategy For Hexapod Gait Transition, Naga Harika Darbha
An Optimization Strategy For Hexapod Gait Transition, Naga Harika Darbha
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Legged robots often need to move through different terrains as they function. This requires a change of gaits by the robot in order to move with better efficiency. There has been a lot of research done to find out which gait works better for a given terrain so that the robot can change its gait accordingly. A reliable analysis of when exactly should the transition take place in a walking robot is important, so that there can be an assurance of stability in the locomotion of the robot during the transition between different gaits. This work presents analysis performed on …
Design Of A Programmable Four-Preset Guitar Pedal, Michael Trombley
Design Of A Programmable Four-Preset Guitar Pedal, Michael Trombley
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Many companies in the music industry offer programmable preset guitar pedals. Presets allow musicians to save time and focus on their act by recalling predetermined settings during a performance. A majority of the companies in the music industry offer up to hundreds of presets, but realistically the substantial amount of presets may have a negative effect on the musician’s performance due to time constraints. The main contribution of this thesis is to address the musician by reducing the amount of presets offered in a guitar pedal design. Combining two systems, a digital control and audio processing circuit, will produce a …
Bistatic Sar Polar Format Image Formation: Distortion Correction And Scene Size Limits, Davin Mao
Bistatic Sar Polar Format Image Formation: Distortion Correction And Scene Size Limits, Davin Mao
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The polar format algorithm (PFA) for bistatic synthetic aperture radar (SAR) image formation offers the compromise between image quality and computational complexity afforded by PFA, while enabling the geometric flexibility of a bistatic collection scenario. The use of the far-field approximation (FFA), which enables the use of the two-dimensional (2D) fast Fourier transform (FFT) in PFA, introduces spatially-varying distortion and defocus effects causing geometric warping and blurring in the resulting image. In this thesis, the residual phase errors due to the FFA are analyzed by decomposing the residual phase errors in the time dimension into their constant, linear, and quadratic …
An Engage Or Retreat Differential Game With Two Targets, Bikash Shrestha
An Engage Or Retreat Differential Game With Two Targets, Bikash Shrestha
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This thesis develops the equilibrium solution for a two-target engage or retreat differential game. In this game, the attacking player is modeled as a massless particle moving with simple motion about an infinite, obstacle-free plane. The opposing player, referred to as the defender, is tasked with the protection of two high-value targets. The mobile attacker must choose to either engage one of the high-value targets or retreat across a predefined boundary. Simultaneously, the defensive player must choose whether to minimize or maximize the attacker's integral utility in an effort to persuade the attacker to choose retreat from certain initial conditions. …
Gnss Receiver Testing And Algorithm Development, Rachael E. Kolker
Gnss Receiver Testing And Algorithm Development, Rachael E. Kolker
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Many current GNSS Software Defined Receivers (SDRs) are often limited in what they can do across a range of developmental applications. They cannot perform acquisition and tracking without several iterations of coding, which does not allow for fast processing. This work provides a Matlab SDR that is based on freely available and optimized components that can be applied to all GNSS signals. A previous basis has been expanded upon to perform tracking of QZSS signals. In addition to this, two separate hardware front ends were compared and their differences analyzed. These hardware systems collected data with different disciplining clocks, but …
Plasma Property Estimation From Dual-Wavelength Interferometry, Andrew J. Hamilton
Plasma Property Estimation From Dual-Wavelength Interferometry, Andrew J. Hamilton
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Diagnostics are necessary for measurement of plasma parameters such as electron, ion and atomic densities, electron temperature, plasma expansion velocity and spatial resolution of density gradients. These parameters play a critical role in defining how a plasma will interact with electromagnetic radiation. For example, the plasma black-out phenomenon occurs when electromagnetic waves are at frequencies below the plasma frequency, where plasma frequency is a function of electron density. Wave propagation diagnostics can improve understanding of a plasma when measurement supports parameter estimation. In this report, the dual-wavelength interferometry method provides a single diagnostic capability to measure plasma expansion velocity, atomic …
Incorporating Passive Compliance For Reduced Motor Loading During Legged Walking, Akhil Sai Pabbu
Incorporating Passive Compliance For Reduced Motor Loading During Legged Walking, Akhil Sai Pabbu
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For purposes of travelling on all-terrains surfaces that are both uneven and discontinuous, legged robots have upper-hand over wheeled and tracked vehicles. The robot used in this thesis is a simulated hexapod with 3 degrees of freedom per leg. The main aim is to reduce the energy consumption of the system during walking by attaching a passive linear spring to each leg which will aid the motors and reduce the torque required while walking. Firstly, the ideal stiffness and location or the coordinates for mounting the spring is found out using gradient based algorithm called `Simultaneous Perturbation and Stochastic Approximation …
Novel Implementation Of Finite Field Multipliers Over Gf(2m) For Emerging Cryptographic Applications, Nazeem Basha Shaik
Novel Implementation Of Finite Field Multipliers Over Gf(2m) For Emerging Cryptographic Applications, Nazeem Basha Shaik
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Cryptographic and coding theory algorithms use arithmetic operations over finite fields. Finite field multiplications over GF(2m) are critical components for these systems. Well known irreducible polynomials are all-one-polynomials (AOP), equally spaced polynomial (ESP), trinomial and pentanomial. Due to its simple structure, AOP based multiplica- tion is easy to implement and hence the AOP based multiplication of variable length can be used as a standard computation core. In this thesis, first of all, we employ low register complexity AOP based systolic multiplication core to propose multiplication over GF(2m) based on NIST recommended pentanomials. The proposed parallel and serial ar- chitectures use …
Analysis And Design Of High-Frequency Soft-Switching Dc-Dc Converter For Wireless Power Charging Applications, Abhishek V. Danekar
Analysis And Design Of High-Frequency Soft-Switching Dc-Dc Converter For Wireless Power Charging Applications, Abhishek V. Danekar
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Wireless power transfer (WPT) technology is becoming attractive in a wide variety of applications such as electric-vehicle charging, induction heating, charging portable applications, industrial robots, and biomedical implants. Recent studies have shown various techniques to implement wireless power transfer and these techniques differ based on the type of applications. For example, for electric vehicle charging, the power levels are in the range 5 kW to 25 kW and the operating frequency is in the range 70 kHz to 110 kHz. On the other hand, for consumer applications, the power levels vary from a few watts to hundreds of watts and …
Implementation Of High Speed And Low Power Radix-4 8*8 Booth Multiplier In Cmos 32nm Technology, Rishit Navinbhai Patel
Implementation Of High Speed And Low Power Radix-4 8*8 Booth Multiplier In Cmos 32nm Technology, Rishit Navinbhai Patel
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According to Moore’s law, number of transistors integrated on a single chip double every 18 months with a lot new functionality embedded, which results the increasing of delay and power consumption of a chip. To improve the performance of a more complicated digital circuit design, faster and power efficient digital sub-components are in urgent need. Multipliers are the key components in the field of DSP, GPU and CPU which compute enormous amount of binary data. A radix-4 8*8 booth multiplier is proposed and implemented in this thesis aiming to reduce power delay product. Four stages with different architecture are used …
Rf Cmos Tunable Gilbert Mixer With Wide Tuning Frequency And Controllable Bandwidth: Design Sythesis And Verification, Xin Hu
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The double-balanced Gilbert mixer is widely used in RF receivers. In general, it is desirable to design a wide tuning frequency Gilbert mixer for low power, high conversion gain, low noise figure, and good linearity, but they are not easy to attain simultaneously. Therefore, trade-offs always exist by tuning design parameters. To observe the trade-off relationship between each tunable parameter and to make a mixer achieve specified requirements easily (i.e., tuning frequency range, bandwidth, and power), an automated design synthesis and verification approach for Gilbert mixer is proposed. A wide tuning CMOS Gilbert mixer design synthesis while keeping the local …
Improvement Of Continuous Wave Radar Measurements In A Partially Controlled Environment, Jared Smith
Improvement Of Continuous Wave Radar Measurements In A Partially Controlled Environment, Jared Smith
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A continuous wave (CW) radar system within a partially controlled environment measures scale model aircraft for mono-static and fully polarimetric radar imaging. Due to a pseudo-far-field setup, wavefront curvature manifests primarily as geometric distortion. Recently proposed phase error models show induced geometric distortion to be independent of aperture size which are verified via measurement for Sensors and Signals Exploitation Laboratory (SSEL) collections. The partially controlled nature of the SSEL introduces stray infrastructural reflections into the measured data. Three methods to reduce stray signals are explored namely: true background subtraction (TBS), running average (RA), and spatial filtering (SF). Of the three …
Extended Kalman Filter And Lqr Controller Design For Quadrotor Uavs, Muneeb Masood Raja
Extended Kalman Filter And Lqr Controller Design For Quadrotor Uavs, Muneeb Masood Raja
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A quadrotor is a unique class of UAVs with vertical take off and landing (VTOL) capability and has attracted significant attention due to its importance in various applications. This thesis presents the design and experimental implementation of Extended Kalman Filters (EKFs) to estimate the states of a quadrotor and a Linear Quadratic Regulator (LQR) controller with integral action to meet the desired control objectives. In case of the Extended Kalman Filters, two different situations are considered: (1) all the states including the Inertial Measurement Unit (IMU) biases are estimated; (2) only the attitude, altitude, and vertical velocity are estimated. The …
Implementation Of Rf Steganography Based Joint Radar/Communication Lfm Waveform Using Software Defined Radio, Dimitri Dessources
Implementation Of Rf Steganography Based Joint Radar/Communication Lfm Waveform Using Software Defined Radio, Dimitri Dessources
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Incident Command System provides a framework for commanders to manage an incident. However, maintaining good situation awareness in an emergency situation is often challenging to the Incident Commander. Stress may result in task fixation which may cause the commander to miss critical information and can eventually lead to poor decisions. The proposed augmented decision support system, with an integrated knowledge base, enhances the commander's decision making and situation awareness by presenting the information that may have been missed. The system has been evaluated to investigate its utility in chemical hazard scenarios. The system was used by experienced Incident Commanders to …
A Comparative Study Of Bagging And Boosting Of Supervised And Unsupervised Classifiers For Outliers Detection, Yue Dang
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The problem of outlier detection has received increasing attention recently because it plays a great role in many fields such as credit fraud detection, cyber security, etc. Machine Learning approach is an excellent choice for outlier detection due to its accuracy and efficiency. Outlier detection problem is unique due to the so-called classes imbalance: the inliers are extreme majority and the outliers are minority. Ensemble methods are popular in classification and regression task in practice to improve the performance of machine learning algorithms. Bagging and boosting are two common methods of them. In this thesis, we want to show the …
Incorporating Passive Compliance For Reduced Motor Loading During Legged Walking, Akhil Sai Pabbu
Incorporating Passive Compliance For Reduced Motor Loading During Legged Walking, Akhil Sai Pabbu
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For purposes of travelling on all-terrains surfaces that are both uneven and discontinuous, legged robots have upper-hand over wheeled and tracked vehicles. The robot used in this thesis is a simulated hexapod with 3 degrees of freedom per leg. The main aim is to reduce the energy consumption of the system during walking by attaching a passive linear spring to each leg which will aid the motors and reduce the torque required while walking. Firstly, the ideal stiffness and location or the coordinates for mounting the spring is found out using gradient based algorithm called `Simultaneous Perturbation and Stochastic Approximation …
Design And Demonstration Of A Physical, Multi-Agent Autonomous Controller Testbed, Eric A. Nees
Design And Demonstration Of A Physical, Multi-Agent Autonomous Controller Testbed, Eric A. Nees
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Navigation and control algorithms are often tested in a simulated environment before being deployed in physical systems. Although simulated environments provide a controlled setting to carefully evaluate performance, the designed scenarios are sometimes unrealistically ideal and may unintentionally omit circumstances or unmodeled interactions. This thesis presents the design, implementation, and practical demonstration of a physical testbed that enables the testing of multi-agent autonomous strategies in hardware on a small scale. Testing the algorithms at scale allows real-time exploration of the interaction and performance of both human and autonomous algorithms under non-ideal conditions while avoiding the costs and risks of full-scale, …
Last Two Surface Range Detector For Direct Detection Multisurface Flash Lidar In 90nm Cmos Technology, Douglas Preston
Last Two Surface Range Detector For Direct Detection Multisurface Flash Lidar In 90nm Cmos Technology, Douglas Preston
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This thesis explores a novel detection architecture for use in a Direct-Detect Flash LIDAR system. The proposed architecture implements detection of the last two surfaces within single pixels of a target scene. The novel, focal plane integrated detector design allows for detection of objects behind sparse and/or partially reflective covering such as forest canopy. The proposed detector would be duplicated and manufactured on-chip behind each avalanche photodiode within a focal plane array. Analog outputs are used to minimize interference from digital components on the analog input signal. The proposed architecture is a low-footprint solution which requires low computational post-processing. Additionally, …