Browsing by Subject "MATLAB"
Now showing 1 - 15 of 15
Results Per Page
Sort Options
Item A high performance class-D amplifier with cascaded sigma-delta modulators(Texas Tech University, 2004-05) Trehan, ChintanThe focus of this thesis is on analysis, simulation and board level implementation of the proposed Class-D power amplifier architecture. The structural design consists of two Sigma-Delta Modulator (SDM) stages in cascade with an intermediate decimation-filter between them. Noise and high tone introduced at the first- stage is filter out through the decimation filter. The signal is converted to a 1-bit Pulse Duration Modulation (PDM) signal by the second stage SDM. The H-Bridge is made part of the SD loop, which enables not only the noise shaping of the quantization noise but also stabilizes the output power switching stage. Output of the H-Bridge is converted to a digital signal using a comparator and latch circuitry and is fed back. To further increase the linearity and performance, high frequency ripples introduced at the H-Bridge is quantized by using a 4-bit SD Analog-to-Digital Converter (ADC) in the feedback loop. Due to the intermediate digital stage and the feedback control at the output stage, the proposed structure has high efficiency and linearity and still is very compact making it possible for wide range of applications.Item Algorithms for Incorporation of Dynamic Recovery in Estimating Frequency of Critical Station Blackout(2012-07-16) Rodi, Paul J.This thesis involves exploring enhancement of estimating the probability of a critical station blackout in nuclear power plant operations by the use of direct numerical evaluation of multidimensional nonrecovery integrals. This requires development of computational methods with data provided from South Texas Project Nuclear Operating Company (STPNOC). Several methods that are currently used in the industry to estimate such probabilities often overestimate the value substantially. The computational integral method developed in the thesis will reduce excess conservatism while maintaining plant safety standards. This computational integral is calculated using a MATLAB research code referred to generally as "STP-TAMIL" which is for South Texas Project --Texas A&M Improved LOOP. The code itself (along with the user manual) was developed in conjunction with this Thesis. STP-TAMIL is successful in reducing the estimated probability of critical station blackout by a significant amount (about 88.47 percent ) with the incorporation of recovery of offsite and onsite power for South Texas Project? s nuclear plants, and results were verified. This thesis also describes an asymptotic justification for to the non-recovery integral used. Applications to the industry, or STPNOC, which will use the "TAMIL" code are addressed. Some assumptions used throughout the problem suggest that if more dynamic rates or distributions are used then more recovery can be obtained, which will decrease the probability of critical station blackout. Methodology developed in this thesis will be used in future work to develop this STP-TAMIL research code into a model used industry wide in commercial nuclear power plants.Item An EEG feature selection toolbox for EEGLAB in the matlab environment(2011-08) Kerr, Andy S; Baker, Mary C.; Pal, RanadipA complete system is proposed to generate features from raw EEG data and qausi-optimally reduce the feature set based on classification rates. Several default features are included for generating feature sets, and the feature set is qausi-optimally reduced using stepwise regression algorithms based on the classification of known classes. A plug-in known as the Feature Selection Toolbox was developed for the open source EEGLAB toolbox within the MATLAB environment to accomplish the goals of this thesis. Synchrony measures of the EEG are becoming more common as a means to establish network links and general comparisons of different areas of the brain. The four default features included in the Feature Selection Toolbox are average power, correlation coefficient, magnitude squared coherence, and phase synchrony index. An exhaustive search is impractical in finding an optimal subset of features as the computational time increases exponentially with the number of desired features in the optimal subset. Three stepwise regression feature selection algorithms are implemented to select the near optimal feature subset with a nearly linear increase in computational time as the maximum number of selected features increases. An example study comparing Alzheimer's Disease to Mild Cognitive Impairment and controls demonstrates the usefulness of the tools developed as part of this thesis. Also, the tradeoffs of different options in the Feature Selection Toolbox are assessed from the results of the algorithm in classifying the responses of individuals to two different cognitive tasks, one involving visual stimulus and counting, the other involving visual stimulus and spatial reasoning.Item An efficient method for approximating products of functions of matrices with vectors(Texas Tech University, 2004-05) Martines, Ian PabloGiven an n x n symmetric positive definite matrix A and a vector c, numerical methods for approximating A1/mc, e^Ac, and ln(A)c are developed, analyzed, and computationally tested. Each method applies Gragg's method with Richardson extrapolation to numerically solve specific initial-value problems to approximate A1/mc, e^Ac, and ln(A)c. Reduction of A to tridiagonal form is first performed to increase the efficiency of the method.Item Analysis of a novel thermoelectric generator in the built environment(2011-08) Lozano, Adolfo; Webber, Michael E., 1971-; Schmidt, Philip S.This study centered on a novel thermoelectric generator (TEG) integrated into the built environment. Designed by Watts Thermoelectric LLC, the TEG is essentially a novel assembly of thermoelectric modules whose required temperature differential is supplied by hot and cold streams of water flowing through the TEG. Per its recommended operating conditions, the TEG nominally generates 83 Watts of electrical power. In its default configuration in the built environment, solar-thermal energy serves as the TEG’s hot stream source and geothermal energy serves as its cold stream source. Two systems-level, thermodynamic analyses were performed, which were based on the TEG’s upcoming characterization testing, scheduled to occur later in 2011 in Detroit, Michigan. The first analysis considered the TEG coupled with a solar collector system. A numerical model of the coupled system was constructed in order to estimate the system’s annual energetic performance. It was determined numerically that over the course of a sample year, the solar collector system could deliver 39.73 megawatt-hours (MWh) of thermal energy to the TEG. The TEG converted that thermal energy into a net of 266.5 kilowatt-hours of electricity in that year. The second analysis focused on the TEG itself during operation with the purpose of providing a preliminary thermodynamic characterization of the TEG. Using experimental data, this analysis found the TEG’s operating efficiency to be 1.72%. Next, the annual emissions that would be avoided by implementing the zero-emission TEG were considered. The emission factor of Michigan’s electric grid, RFCM, was calculated to be 0.830 tons of carbon dioxide-equivalent (CO2e) per MWh, and with the TEG’s annual energy output, it was concluded that 0.221 tons CO2e would be avoided each year with the TEG. It is important to note that the TEG can be linearly scaled up by including additional modules. Thus, these benefits can be multiplied through the incorporation of more TEG units. Finally, the levelized cost of electricity (LCOE) of the TEG integrated into the built environment with the solar-thermal hot source and passive ground-based cold source was considered. The LCOE of the system was estimated to be approximately $8,404/MWh, which is substantially greater than current generation technologies. Note that this calculation was based on one particular configuration with a particular and narrow set of assumptions, and is not intended to be a general conclusion about TEG systems overall. It was concluded that while solar-thermal energy systems can sustain the TEG, they are capital-intensive and therefore not economically suitable for the TEG given the assumptions of this analysis. In the end, because of the large costs associated with the solar-thermal system, waste heat recovery is proposed as a potentially more cost-effective provider of the TEG’s hot stream source.Item Development and assessment of CFD models including a supplemental program code for analyzing buoyancy-driven flows through BWR fuel assemblies in SFP complete LOCA scenarios(2012-12) Artnak, Edward Joseph; Biegalski, Steven R.; Howell, John R.; Schulz, Karl W.; Deinert, Mark R.; da Silva, Alexandre K.This work seeks to illustrate the potential benefits afforded by implementing aspects of fluid dynamics, especially the latest computational fluid dynamics (CFD) modeling approach, through numerical experimentation and the traditional discipline of physical experimentation to improve the calibration of the severe reactor accident analysis code, MELCOR, in one of several spent fuel pool (SFP) complete loss-of-coolant accident (LOCA) scenarios. While the scope of experimental work performed by Sandia National Laboratories (SNL) extends well beyond that which is reasonably addressed by our allotted resources and computational time in accordance with initial project allocations to complete the report, these simulated case trials produced a significant array of supplementary high-fidelity solutions and hydraulic flow-field data in support of SNL research objectives. Results contained herein show FLUENT CFD model representations of a 9x9 BWR fuel assembly in conditions corresponding to a complete loss-of-coolant accident scenario. In addition to the CFD model developments, a MATLAB based control-volume model was constructed to independently assess the 9x9 BWR fuel assembly under similar accident scenarios. The data produced from this work show that FLUENT CFD models are capable of resolving complex flow fields within a BWR fuel assembly in the realm of buoyancy-induced mass flow rates and that characteristic hydraulic parameters from such CFD simulations (or physical experiments) are reasonably employed in corresponding constitutive correlations for developing simplified numerical models of comparable solution accuracy.Item Effective power factor : analysis and implementation(2011-05) Shan, Lianfei; Santoso, Surya; Grady, WilliamThe study reviews and examines the definitions of reactive power, apparent power, and power factor. Among the different definitions of power factor in three-phase circuits under a non-sinusoidal condition, this study adopts the definition of the effective power factor, which is also advocated by IEEE Standard 1459-2010. The effective power factor is defined as the ratio of the real power consumed by the load over the effective apparent power. The effective apparent power is the maximum power transmitted to the load (or delivered by a source) while keeping the same line losses and the same load (or source) voltage and current. The effective power factor theory gives apparent power a definite physical significance and provides more insights than other definitions in unbalanced circuits. Another merit of the effective power factor definition is that it only involves measurements and computations in the time domain. This study implements the computation of the effective power factor in MATLAB for use in PSCAD/EMTDC. The latter simulates the power system and provides three-phase voltage and current measurements. MATLAB performs the effective power factor computation and sends the results back to PSCAD. A number of simulations are provided in this report to demonstrate the validity and the accuracy of this implementation.Item Electromagnetic emissions reduction in a CAN transceiver system(Texas Tech University, 2004-05) Slayton, Jason RThis project deals with the emissions behavior of a Controller Area Network (CAN). CAN systems are widely used in automotive applications. Recently, CAN systems have expanded their applications to fields like medical, industrial automation and even high end home appliances. This paper discussed the important features of using CAN systems, one of which is the electromagnetic emissions behavior of the systems, especially in automotive applications. The motivation for the research discussed in this paper is to gain a better understanding of the effect different signals has on emissions. The most widely accepted solution to this problem is using a common mode capacitor on the signals. This reduces the variation of the common mode signal, which, in turn, reduces the emissions. This signal variation, along with other variations, was evaluated in this research. The objectives of this research are to quantify the effect each signal variation has on emissions.Item A fundamental approximation in MATLAB of the efficiency of an automotive differential in transmitting rotational kinetic energy(2012-05) Vaughn, James Roy; Matthews, Ronald D.; Bryant, Michael D.The VCOST budgeting tool uses a drive cycle simulator to improve fuel economy predictions for vehicle fleets. This drive cycle simulator needs to predict the efficiency of various components of the vehicle's powertrain including any differentials. Existing differential efficiency models either lack accuracy over the operating conditions considered or require too great an investment. A fundamental model for differential efficiency is a cost-effective solution for predicting the odd behaviors unique to a differential. The differential efficiency model itself combines the torque balance equation and the Navier-Stokes equations with models for gear pair, bearing, and seal efficiencies under a set of appropriate assumptions. Comparison of the model with existing data has shown that observable trends in differential efficiency are reproducible in some cases to within 10% of the accepted efficiency value over a range of torques and speeds that represents the operating conditions of the differential. Though the model is generally an improvement over existing curve fits, the potential exists for further improvement to the accuracy of the model. When the model performs correctly, it represents an immense savings over collecting data with comparable accuracy.Item Iterative approach to deformable membrane design(Texas Tech University, 2004-05) Nellore, Prashanth RA continuous deformable membrane mirror can be fabricated using MEMS processes. It will have a highly reflective thin membrane, which is the mirror surface, and a number of actuators below it. The shape of the mirror surface is controlled by inducing an electrostatic force through applying a voltage between the mirror surface and the actuators. Small displacements of a membrane under tension are governed by Poisson's equation. The solutions of this equation determine the deflections in the vertical direction for different pressures applied at various surface points, due to various electrode positions. This thesis examines the influence of number, position, thickness of the electrodes and also the electrostatic pressure applied by each electrode on the surface of the mirror. A Matlab Graphical User Interface is designed that computes the deflections and uses iterative methods to optimize the voltages on the electrodes, their position and thickness. It produces a deformable membrane design that will match the surface of the mirror to that of a spherical mirror of known radius of curvature.Item MATLAB GUI-based toolbox for the design of modulated perfect reconstruction filter banks(Texas Tech University, 2004-05) Zhao, JieThe aim of this study is to create a Graphical User Interface (GUI) toolbox. This Matlab based toolbox will provide a number of options for designing and implementing maximally decimated cosine-modulated perfect reconstruction (PR) filter banks. Using this toolbox, people can design their own filter banks without having to understand the details of the design procedure. In this thesis, the theory of and results from cosine-modulated filter banks are reviewed. The prototype filters have arbitrary lengths, and the overall delay of the filter bank is arbitrary within a fundamental range. Necessary and sufficient conditions for PR are presented using a polyphase representation. The design is formulated as a quadratic-constrained least-squares optimization problem, where the optimized parameters are the prototype filter coefficients. Design and description of the toolbox is provided in this thesis. Several design examples are given to illustrate the tradeoff between overall system delay and stopband attenuation.Item Representation of control systems using Java(Texas Tech University, 1998-12) Conn, James NealNot availableItem Software design and implementation of a video data acquisition and replay system(Texas Tech University, 2004-05) Helene, Sigi Jessica St.The objective of this paper involves using the waterfall approach model to design a bespoke product system to test video signals in a test lab. The thesis goes into depth describing the system requirements, design and implementation of a Video Data Acquisition and Replay (VIDAR). VIDAR allows video signals to be fed into a hardware system, downloaded onto a computer, and outputted onto a video system such as a television.Item Statewise Correlates of Civil Nuclear Energy(2014-08-01) Kafle, NischalQuantitative empirical analysis has been used in several works, over the past decade or so, to identify correlates of states motivation for pursuing military nuclear technology. Nelson and Sprecher used such methodology to identify various national attributes that correlate to states peaceful use of nuclear power for electricity generation, which was termed as \Nuclear Reliance." The major initial objective for the present work was to replace a dichotomous subjective independent variable used by Nelson and Sprecher to represent engagement in international commerce in civil nuclear technology with more objectively defined variables carrying a similar representation. Ordinary least squares stepwise regression was applied to a dataset consisting of 27 independent variables that was created for this study. Data for 13 of 27 independent variables were added to the dataset from previous study, and 9 of 14 previous attributes data were updated. Supervised stepwise regression was used to create a linear regression model with five predictors having acceptable confidence level (p < 0:01) and coefficient of determination (R^(2) ? 0:51). Results from stepwise linear regression showed that states that trade knowledge and material for nuclear power technology are heavily involved in civil nuclear power that states that are not involved in international trade of such technology and material. Analyses of the individual steps at several different levels of aggregation showed that some predictors were included as a consequence of improvements to residuals only for a few states. Preliminary results show that an analysis based on change from some prior year (1980 was used, for illustrative purposes) has considerable promise.Item Trajectory generation using a modified simple shooting method(Texas Tech University, 2004-05) Trent, Ashley DeneeceNot available