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Articles 961 - 990 of 1189
Full-Text Articles in Engineering
Computer-Based Skeletal Age Assessment Using Hand/Wrist Radiographs In Children 8-18 Years Old, Zhihong Ni
Computer-Based Skeletal Age Assessment Using Hand/Wrist Radiographs In Children 8-18 Years Old, Zhihong Ni
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Children's skeletons mature at different rates, and they can be affected by a variety of factors including disease, hormone imbalance or genetics. The assessment of skeletal maturity is a frequently performed procedure that allows the detection of hormonal, growth or genetic disorders. Several methods have been developed to estimate skeletal maturity. Most methods evaluate hand/wrist radiographs using indicators such as the ratios of various bone widths, the onset of the ossification of epiphysis and epiphyseal-diaphyseal fusion. Among those methods, the FELS method differs from others in the application of different grades to each indicator and the provision of a confidence …
Adaptive Thresholding For Detection Of Radar Receiver Signals, Stephen R. Benson
Adaptive Thresholding For Detection Of Radar Receiver Signals, Stephen R. Benson
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Digital microwave receivers play a critical role in many of today's modern radar tracking systems. The need for these digital receivers to push the boundaries in terms of bandwidth and input dynamic ranges (DR) is vital for their use in radar signal tracking. Significant research has been conducted in the area of the fast Fourier transform (FFT) to aid in continuing to enhance the performance capabilities of digital microwave receivers. However, with the advancement and increased complexity of these systems, the need for an efficient and effective adaptive thresholding technique is becoming ever more present.
The proposed adaptive thresholding technique …
Risk Quantification And Reliability Based Design Optimization In Reusable Launch Vehicles, Jason Maxwell King
Risk Quantification And Reliability Based Design Optimization In Reusable Launch Vehicles, Jason Maxwell King
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Due to the inherent natural variability of parameters with reusable launch vehicles, design considerations without use of a reliability or safety index may be unreliable and vulnerable to vehicle failures. Generally in preliminary air vehicle design little information is known regarding design variable uncertainties, consequently requiring a technique that can quantify epistemic uncertainties. Evidence Theory is employed to accomplish this task resulting in a reliability bound of belief and plausibility. Due to the discontinuous nature of the belief and plausibility function it is necessary to implement a continuous function known as plausibility decision to be used to calculate sensitivities that …
Design And Validation Of A Sensor Integration And Feature Fusion Test-Bed For Image-Based Pattern Recognition Applications, Hrishikesh Karvir
Design And Validation Of A Sensor Integration And Feature Fusion Test-Bed For Image-Based Pattern Recognition Applications, Hrishikesh Karvir
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We integrated a sensor hardware test-bed using scientific grade, commercial off-the-shelf (COTS) technology and developed supporting software to enable rapid prototyping. The validity of this test-bed and associated software was demonstrated through the delivery of a ground-based multispectral visual surveillance prototype for improvised explosive devices (IED) detection using electro-optical (EO) and short-wave infrared (SWIR) cameras. Software developed to support the test-bed included modules for image acquisition, preconditioning, segmentation, feature extraction, data regularization and pattern recognition. To provide spatially co-aligned data, we optimized a mutual information-based image registration algorithm to improve its convergence rate and benchmarked it against the established simplex …
Use Of Web-Based Lessons Of Statistical Concepts With Graphics And Animation To Enhance The Effectiveness Of Learning, Lavanya Pillala
Use Of Web-Based Lessons Of Statistical Concepts With Graphics And Animation To Enhance The Effectiveness Of Learning, Lavanya Pillala
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Statistics is of critical importance to engineers. However, many engineering students struggle to grasp the meaning of statistical concepts and the idiosyncrasies of statistical methodologies. Because of this problem, instructors of statistics are constantly searching for better ways to help students understand statistical concepts. The goal of this project is to design and develop web-based lessons that use graphics and animations to enhance the effectiveness of students' learning of statistical concepts.
Lessons of three important statistical concepts have been developed for this thesis - normal distribution, central limit theorem and confidence & tolerance intervals - following well-recognized instructional design development …
Relative Stability Of The Inner-Current Loop Of Peak Current-Mode Controlled Pwm Dc-Dc Converters In Ccm, Nisha Kondrath
Relative Stability Of The Inner-Current Loop Of Peak Current-Mode Controlled Pwm Dc-Dc Converters In Ccm, Nisha Kondrath
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Current-mode control is a commonly adopted method of regulation for pulse-width modulated (PWM) dc-dc power converters in industry, but is not well understood. The advantages of current-mode control over the voltage-mode control include inherent overload and short circuit protection, faster response, line-noise rejection, and multiple converter paralleling. Current-mode controlled system consists of (1) an inner-current loop and (2) an outer-voltage loop, which sets the reference voltage to the inner loop. To ensure stable operation of the multi-loop converter, all the sequential loops in the circuit should be stable with sufficient degree of stability. The research in this dissertation is focused …
Design, Modeling, Fabrication And Characterization Of Three-Dimensional Ferromagnetic-Core Solenoid Inductors In Su-8 Interposer Layer For Embedded Passive Component Integration With Active Chips, Robert Carl Fitch Jr.
Design, Modeling, Fabrication And Characterization Of Three-Dimensional Ferromagnetic-Core Solenoid Inductors In Su-8 Interposer Layer For Embedded Passive Component Integration With Active Chips, Robert Carl Fitch Jr.
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Integrated circuit technology continually presses toward higher transistor density and thus smaller dimensions, yet passive components which remain the bulk of the circuit area, surprisingly receive sideline attention. This work addresses a niche area of inductor design as it applies to the 3-dimensional (3-D) integration of active transistors and passive components. Hybrid, 3-D circuits residing on inexpensive silicon substrates can be fashioned using a photosensitive epoxy known as SU-8 serving as the interposer layer between the substrate and in which the passive components are embedded. The active components, which are known-good-chips, are secured with epoxy into deep reactive ion etched …
A Structured Asic Approach To A Radiation Hardened By Design Digital Single Sideband Modulator For Digital Radio Frequency Memories, Thomas B. Pemberton
A Structured Asic Approach To A Radiation Hardened By Design Digital Single Sideband Modulator For Digital Radio Frequency Memories, Thomas B. Pemberton
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Digital Radio Frequency Memories (DRFM) are widely used as modules in digital signal processing. These modules can provide several forms of signal manipulation and storage capabilities. With single event effects caused by environmental radiation the need for a radiation hardened DRFM is increased. Typical radiation hardening involves the use of specialized foundries utilizing proprietary CMOS libraries that are expensive to build or adding lead packages around a chip that is expensive and add weight to the chip. An alternative radiation hardening technique is to utilize a radiation hardened by design library. This library includes digital gates that have been hardened …
Stochastic Mistuning Simulation Of Integrally Bladed Rotors Using Nominal And Non-Nominal Component Mode Synthesis Methods, Joseph A. Beck
Stochastic Mistuning Simulation Of Integrally Bladed Rotors Using Nominal And Non-Nominal Component Mode Synthesis Methods, Joseph A. Beck
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Mistuning prediction in integrally bladed rotors is often done with reduced order models that minimize computational expenses. A common model reduction technique used for mistuning applications is the component mode synthesis method. In this work, two modern component mode synthesis methods are used to generate mistuned response distributions that will be used to determine if the two methods are statistically indistinguishable. The first method, nominal mode approximation, assumes an airfoil geometric perturbation alters only the corresponding substructure modal stiffnesses while its mode shapes remain unaffected. The mistuned response is then predicted by a summation of the nominal modes. The second …
Development Of A Remote Medical Image Browsing And Interaction System, Wei Ye
Development Of A Remote Medical Image Browsing And Interaction System, Wei Ye
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In this thesis a new capability - remote image browsing built upon our existing music telepresence platform is introduced. The implementation of this new image capability has two parts: one part is the local image viewing and the other part is distributed image-view interaction. Image viewing part is realized using the foundation of Linux GTK+ library. Most popular lossless and lossy image coding formats such as GIF, PNG, BMP and JPEG are supported currently. Image viewing part also provides several image operations such as: zoom in and zoom out, image information display and moreover users can select their own regions …
An Automated Approach To A 90-Nm Cmos Drfm Dssm Circuit Design, Thomas A. Hopkins
An Automated Approach To A 90-Nm Cmos Drfm Dssm Circuit Design, Thomas A. Hopkins
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A digital single sideband modulator (DSSM) for a digital radio frequency memory (DRFM) was designed and implemented in a commercial 90-nm radiation-hardened-by-design (RHBD) structured ASIC by Thomas Pemberton in cite{Pemberton}. This thesis synthesized the same DSSM structure in a non-hardened 90-nm commercial process and compared the synthesis results of the two for power, delay, and area. The number of I/O bits and taps in cite{Pemberton} and this thesis were purposely made high to create a large target for radiation testing. As should be expected, the RHBD DSSM reported greater power and area. However, the RHBD power models were only estimates. …
Finding Cadaveric Human Head Masses And Center Of Gravity: A Comparison Of Direct Measurement To 3d Ing, Grant Corwin Roush
Finding Cadaveric Human Head Masses And Center Of Gravity: A Comparison Of Direct Measurement To 3d Ing, Grant Corwin Roush
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Mass properties of the human head are critical elements in developing neck injury threshold criteria in acceleration and impact environments. In order to accurately simulate the dynamics of the head in impact and acceleration environments, valid mass properties data for the human head must exist.
The purpose of this study was two-fold: First, to directly measure and generate a useful data set of human head mass properties and anthropometry, and second, compare the results from the direct measurement to measurements obtained using computed tomographic (CT) analyses of the human head. Four cadaveric human heads, all male, were measured.
For the …
Effective Simulation And Optimization Of A Laser Peening Process, Gulshan Singh
Effective Simulation And Optimization Of A Laser Peening Process, Gulshan Singh
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Laser peening (LP) is a surface enhancement technique that has been applied to improve fatigue and corrosion properties of metals. The ability to use a high energy laser pulse to generate shock waves, inducing a compressive residual stress field in metallic materials, has applications in multiple fields such as turbomachinery, airframe structures, and medical appliances. In the past, researchers have investigated the effects of LP parameters experimentally and performed a limited number of simulations on simple geometries. However, monitoring the dynamic, intricate relationships of peened materials experimentally is time consuming, expensive, and challenging.
With increasing applications of LP on complex …
Interfacial Modification Of Microcellular Carbon: Influence Of Ceramic And Carbon Nanotube Coatings, Anil Kumar Karumuri
Interfacial Modification Of Microcellular Carbon: Influence Of Ceramic And Carbon Nanotube Coatings, Anil Kumar Karumuri
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Microcellular carbon is an emerging ultra lightweight and efficient thermal management material, which also has great potential as a reinforcement material for selected composites. However, these porous materials exhibit relatively low mechanical properties, and are susceptible to degradation in oxidizing environment. The scope of this research is to investigate surface modification approaches that can address these issues. Two specific objectives were: (1) to develop ceramic coatings to improve the survivability of carbon foams in high temperature applications, and (2) to develop and test modifications that can improve cellular composites involving carbon foam. It was seen that a mixed layer of …
Integrated Bipolar Plate - Gas Diffusion Layer Design For Polymer Electrolyte Membrane Fuel Cells, David N. Neff
Integrated Bipolar Plate - Gas Diffusion Layer Design For Polymer Electrolyte Membrane Fuel Cells, David N. Neff
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Bipolar plates compose a large portion of the weight and manufacturing costs in fuel cells. Bipolar plates are metal plates that separate each membrane-electrode assembly in a fuel cell stack. They provide structural strength, contain flow channels for fuel transport, and conduct electricity in the fuel cell. Electricity also flows through the gas diffusion layer (GDL) which lies next to the bipolar plate. Because the GDL is separate from the bipolar plate, there is a contact resistance as the electricity flows from one to the other. The scope of this thesis is to research an efficient way of manufacturing a …
Characterization Of Excitatory Amino Acid Neurotransmitters At Motoneuron Synapses Contacting Renshaw Cells, Dannette Shanon Richards
Characterization Of Excitatory Amino Acid Neurotransmitters At Motoneuron Synapses Contacting Renshaw Cells, Dannette Shanon Richards
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Motoneurons are among the best studied neurons in the central nervous system. The motoneuron synapses have been well characterized in the periphery where they release acetylcholine at the neuromuscular junction. However excitatory amino acids also seem to be released from motoneuron terminals in the periphery, and centrally at their synapses contacting Renshaw cells. Although excitatory amino acids are suggested to be released from motoneuron synapses it is not known which excitatory amino acids (either aspartate or glutamate) are released, nor is the mechanism for their release known. To examine the presence and mechanism of release for aspartate and glutamate at …
Dynamic Kernel Function For High-Speed Real-Time Fast Fourier Transform Processors, Yu-Heng George Lee
Dynamic Kernel Function For High-Speed Real-Time Fast Fourier Transform Processors, Yu-Heng George Lee
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The fast Fourier transform (FFT) plays a critical role in many modern applications, such as acoustics, optics, telecommunications, wireless sensor networks, location sensing, patient monitoring, speech, signal detection, and image processing. The input dynamic range, data throughput rate, frequency resolution, bandwidth, design flexibility, hardware consumption, and power requirements for the various applications are vastly different, leading to significant research focusing on different aspects of FFT performance improvement.
The proposed dynamic kernel function uses an efficient fixed-point numerical representation of the twiddle factor and replaces the cumbersome multipliers with simple shift-and-add operations to enhance the data throughput rate for high-speed wideband …
Genetic Differentiation In Ambystomatid Salamanders Across A Fragmented Landscape, Joseph E. Bartoszek
Genetic Differentiation In Ambystomatid Salamanders Across A Fragmented Landscape, Joseph E. Bartoszek
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It is generally recognized that amphibian populations declining across the globe. Habitat loss is the primary cause of decline. The salamander family Ambystomatidae has experienced significantly more rapid decline than the average for amphibians. Coefficients of Conservatism (CoC) have been developed for amphibians in Ohio. These are based primarily on habitat requirements with high CoCs for amphibians with stringent habitat requirements (e.g. vernal pools associated with large, intact, undisturbed forest), and low CoCs for amphibians with less stringent habitat requirements. Genetic diversity in five species and one hybrid complex of ambystomatid salamander in southwest Ohio were examined and compared to …
A Cryptanalysis Methodology For The Reverse Engineering Of Encrypted Information In Images, Allan Anthony Rwabutaza
A Cryptanalysis Methodology For The Reverse Engineering Of Encrypted Information In Images, Allan Anthony Rwabutaza
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Security is an important issue related to the storage and communication of data and information. In data and information security, cryptography and steganography are two of the most common security techniques. On one hand, there is cryptography, which is the secret communication between two parties by message scrambling on the sender's side and message unscrambling on the receiver's side so that only the intended receiver gets the secret message. On the other hand, there is steganography, which is the hiding of information in a medium in such a way that no one other than the sender or the intended receiver …
Development And Evaluation Of A Flexible Framework For The Design Of Autonomous Classifier Systems, Priya Ganapathy
Development And Evaluation Of A Flexible Framework For The Design Of Autonomous Classifier Systems, Priya Ganapathy
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We have established a modular virtual framework to design accurate, robust, efficient and cost-conscious autonomous target/object detection systems. Developed primarily for image-based detection problems, such as automatic target detection or computer-aided diagnosis, our approach is equally suitable for non-image-based pattern recognition problems. The framework features six modules: 1) the detection algorithm module accepts two-dimensional, spatially-coded sensor outputs; 2) the evaluation module uses our receiver operator characteristic (ROC)-like assessment tool to evaluate and fine-tune algorithm outputs; 3) the fusion module compares outputs combined under various fusion schemes; 4) the classifier selection module exploits the double-fault diversity measure (F2 DM) to identify …
An Integrated Simulation Environment Combining Process-Driven And Event-Driven Models, Vishnu Sharma Kesaraju
An Integrated Simulation Environment Combining Process-Driven And Event-Driven Models, Vishnu Sharma Kesaraju
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A simulation framework that integrates process-driven and event-driven approaches offers a powerful combination of tools to the modeler. In process-driven simulation models, the system can be represented by block diagrams or system networks through which entities flow to mimic real life system objects. In event-driven models, the system can be represented by event graphs, which focus on the abstraction of the event rather than on observable physical entities. In this research, a simulation environment is proposed that integrates both the approaches, i.e. process and event. One of the main outcomes of working in such an environment is that modelers can …
Aircraft Thermal Management Using Loop Heat Pipes, Andrew J. Fleming
Aircraft Thermal Management Using Loop Heat Pipes, Andrew J. Fleming
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The objective of this thesis was to determine the feasibility of using loop heat pipes to dissipate waste heat from power electronics to the skin of a fighter aircraft and examine the performance characteristics of a titanium-water loop heat pipe under stationary and elevated acceleration fields. In the past, it has been found that the boundary condition at the condenser can be a controlling factor in the overall performance of this type of thermal management scheme. Therefore, the heat transfer removed from the aircraft skin has been determined by modeling the wing as a flat plate at zero-incidence as a …
Trusted Querying Over Wireless Sensor Networks And Network Security Visualization, Giovani Rimon Abuaitah
Trusted Querying Over Wireless Sensor Networks And Network Security Visualization, Giovani Rimon Abuaitah
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Wireless sensor networks (WSNs) as an emerging technology faces numerous challenges. Sensor nodes are usually resource constrained. Sensor nodes are also vulnerable to physical attacks or node compromises. Answering queries over data is one of the basic functionalities of WSNs. Both resource constraints and security issues make designing mechanisms for data aggregation particularly challenging. In this thesis, we first explore the various security techniques for data aggregation in WSNs then we design and demonstrate the feasibility of an innovative reputation-based framework rooted in rigorous statistical theory and belief theory to characterize the trustworthiness of individual nodes and data queries in …
Determining The Effect Of Speaker's Gender And Speech Synthesis On Callsign Acquisition Test (Cat) Results, Jasminkumar B. Soni
Determining The Effect Of Speaker's Gender And Speech Synthesis On Callsign Acquisition Test (Cat) Results, Jasminkumar B. Soni
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Effective and efficient speech communication is one of the leading factors for success of battlefield operation. With the increases in the levels of gender diversity in military services, it is important to assess the effectiveness of voice for both genders in communication systems. The purpose of this research study was to determine the effect of the speaker's voice (male and female) on the speech intelligibility (SI) performance of the Callsign Acquisition Test (CAT). In addition, the effects of synthesized speech were evaluated. The CAT test is a new SI test that has been developed for military use. A group of …
Separation And Vorticity Transport In Massively-Unsteady Low Reynolds Number Flows, Charles Webb
Separation And Vorticity Transport In Massively-Unsteady Low Reynolds Number Flows, Charles Webb
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There is no doubt that nature has existed as the very inspiration for many of technological achievements of today. Flight is no exception though our conventional methods of flight seem to be completely devoid of any flapping modes commonly seen in insects and birds. This is because the unsteady characteristics of natures keen flight capabilities is very difficult to study. However, as our computational and experimental methods of investigation have improved, our imagination again begins to turn to this one aspect of flight that has eluded man thus far. Birds and more specifically insects are capable of flying at such …
Detection Of Small Aircraft Using An Acoustic Array, Anne M. Zelnio
Detection Of Small Aircraft Using An Acoustic Array, Anne M. Zelnio
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Detection of small aircraft visually or with radar sensors is difficult due to its small size, low-velocity, and low radar cross section. This effort investigates the detection and localization of small aircraft using an acoustic array. The acoustic array was fabricated using low-cost commercial off-the shelf (COTS) hardware that is mobile and can adapt to different signatures and deployment environments. A cross-correlation method for calibration and delay-and-sum beamforming was performed. A generalized likelihood ratio test (GLRT)-based energy detector and a GLRT-based sinusoidal signal detector was applied after beamforming. Detection was also performed using various subpace adaptive beamforming techniques including MUSIC, …
A Guided Neighborhood Search Applied To The Split Delivery Vehicle Routing Problem, Rafael E. Aleman
A Guided Neighborhood Search Applied To The Split Delivery Vehicle Routing Problem, Rafael E. Aleman
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The classic vehicle routing problem considers the distribution of goods to geographically scattered customers from a central depot using a homogeneous fleet of vehicles with finite capacity. Each customer has a known demand and can be visited by exactly one vehicle. Each vehicle services the assigned customers in such a way that all customers are fully supplied and the total service does not exceed the vehicle capacity. In the split delivery vehicle routing problem, a customer can be visited by more than one vehicle, i.e., a customer demand can be split between various vehicles. Allowing split deliveries has been proven …
Fuzzy Logic Control Of A Switched-Inductor Pwm Dc-Dc Buck Converter In Ccm, Terry Kolakowski
Fuzzy Logic Control Of A Switched-Inductor Pwm Dc-Dc Buck Converter In Ccm, Terry Kolakowski
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Modern electronics are operating at lower voltages with higher currents, requiring power converters to deliver these requirements efficiently. In this thesis, a switch-inductor buck converter is designed for the required specifications; and for the selected design, component losses and efficiency are calculated. A MATLAB/Simulink model is constructed, and tested in the presence of load and source disturbances to show the converter cannot maintain the desired output voltage when the disturbances are applied.
A fuzzy logic PID controller is designed to regulate the duty cycle of the converter to control the output voltage. Control surfaces are designed for proportional, integral, and …
Dual Mode Scramjet: A Computational Investigation On Combustor Design And Operation, Ryan Timothy Milligan
Dual Mode Scramjet: A Computational Investigation On Combustor Design And Operation, Ryan Timothy Milligan
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Numerical analysis was performed on a Dual-Mode Scramjet isolator-combustor. Preliminary analysis was performed to form a baseline geometry. Another study validated the results of a 2D model compared to a 3D model. Stable combustion was shown at two different flight conditions, M=3.0 and M=2.5. A marginal 5% decrease in stream thrust was shown by introducing a 50/50 mix of methane and ethylene. Based on the results of the preliminary analysis, detailed geometry analysis was performed on the 3D baseline geometry. Adding a new set of cavity feeding injectors increased the overall stream thrust and the equivalence ratio in the cavity. …
High Voltage Dc Converter Systems Modeling, Simulation And Analysis, Manish A. Dalal
High Voltage Dc Converter Systems Modeling, Simulation And Analysis, Manish A. Dalal
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The thesis provides insights into important modeling techniques to model the converter system, machine design, control and power stages and integration of the various sub systems to simulate the system level performance. This innovative modeling and simulation project is very relevant to optimizing the system performance, designing the sub circuits, components selection, predicting the system stability and impulse responses. The thesis presents modeling and simulation of three different 270VDC converter systems and comparing their performances against each other. The 270VDC converter system accepts either Generator 3-phase AC voltages or fixed three voltage source followed by single or dual converter stages …