Thesis (Ph.D.)--Mississippi State University. Department of Electrical and Computer Engineering. / Title from title screen. Includes bibliographical references.

Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This thesis presents the design and implementation of shunt active power filtering algorithms for unbalanced, non-linear loads. A three-phase four-wire topology is developed in the dqO space. Based on this development an accurate dynamic system model, taking into account the effect of the neutral inductor is developed. The synchronous reference frame technique is expanded to enable the isolation of the zero sequence current component into its instantaneous active and reactive current components. Additionally a prediction method is proposed that will enable the proper prediction of the reference currents in a threephase four-wire system. Two categories of reference current signal tracking algorithms are investigated; namely the predictive current controller and the sliding mode current controller. A compensating technique is proposed to compensate for the effects that sampling and computational time delay have on the performance of the system. Additionally, an investigation is done into the effect that dead-time has on the performance of the system, and based on this investigation a dead-time compensating strategy is proposed. Finally simulation and practical results are provided to validate the discussed theories. / AFRIKAANSE OPSOMMING: Hierdie verhandeling ondersoek die ontwerp en implementering van parralel gekoppelde aktiewe filter algoritmes vir ongebalenseerde, nie-lineêre laste. 'n Drie-fase vier-draad topologie, asook 'n korrekte model van die dinamiese sisteem, wat die effek van die neutraal induktor insluit, is ontwikkel in die dqO ruimte. Die sinchroon verwysing vlak tegniek is uitgebrei om die isolering van die nul sekwensie stroom in onderskeidelik die oombliklike aktiewe en reaktiewe stroom komponente te verdeel. Addisioneel is a vooruitskatting tegniek aanbeveel wat die beheerder in staat sal stelom voldoende die verwysing strome vooruit te skat in 'n drie-fase vier-draad stelsel. Twee katagoriee van verwysing stroom volging algoritmes is ondersoek, naamlik die afskatting stroom beheerder en die gleiende modus stroom beheerder. 'n Effektiewe kompensasie tegniek is voorgestel om die effek van tydvertraging as gevolg van monstering en verwerking te elimineer. Addisioneel is die effek van dooie-tyd ondersoek en gebasseer op hierdie ondersoek is 'n effektiewe dooie-tyd kompensasie tegniek voorgestel. Laastens is simulasies en praktiese resultate verskaf om die werking van die voorgestelde teorie te bevestig.

CNPq / Este trabalho descreve o desenvolvimento de um dispositivo sintonizador de redes de Bragg em fibra óptica que pode ser utilizado como um filtro óptico ou como um sintonizador de canais de comunicação óptica de redes WDM. O dispositivo faz uso de uma peça mecânica que altera o comprimento de onda de Bragg através da compressão da fibra. A peça mecânica é tracionada por um atuador piezoelétrico multicamadas. O dispositivo ainda é composto por um interrogador de redes de Bragg utilizando uma técnica passiva com a utilização de filtro fixo. O filtro fixo utilizado é um cristal com uma camada de filmes finos. O dispositivo é caracterizado utilizando-se duas redes de Bragg e são avaliados os parâmetros dinâmicos do sistema como a resolução em comprimento de onda e velocidade de sintonização. O sistema de interrogação é ainda descrito através do emprego de simulações computacionais e o sistema desenvolvido é comparado com dados obtidos através de simulações. / This work describes the development of a device that can be used as a tunable filter based on a Fiber Bragg Grating or as an optical network switch. The device is made of a mechanical system used to compress the fiber optic in witchi the FGB is inscribed. The mechanical device uses a piezoelectrical multiplayer actuator. The device also contains a passive Fiber Bragg Grating interrogation system using a fixed filter based on a thin film. The device is studied with two FGB and the dynamical characteristics of the systems analyzed, especially the wavelength resolution and the tuning velocity. The device is also investigated using digital simulations and the results are compared with these simulations.

This thesis deals with the design, layout, fabrication, testing and characterization of a second-order filter (biquad) using the transconductance-C (gm-C) technique. The biquad was designed to realize the four filter functions - lowpass, highpass, bandpass and notch - by appropriate choice of input and output terminals and element values. The tunable range of frequencies for the biquad was designed to be 18-59MHz. The quality factor of the biquad was designed to be tunable from approximately 1/3 to 3. The filter was designed in LEVEL2 SPICE, laid out using MAGIC, and the circuit was fabricated using MOSIS's 2μm CMOS analog (n-well) process. The circuit board for testing the chip was designed using the PCB design system -PADS-PCB. The chip was tested using the Network Analyzer HP 4195A. The performance of the filter was then compared with the design objectives and simulation results. Both the pole frequency and the quality factor were found to be tunable by the same factor as the design. Noise analysis showed the output noise to be less than -65dB. The notch function could not be experimentally verified due to high sensitivity of this function to component tolerances and process variations. Power dissipation of the filter was found to be 6m W.

Thesis: Elec. E., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 1976 / Bibliography: leaves 255-263. / by Dennis V. Marsicano. / Elec. E. / Elec. E. Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science

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ABSTRACT The amount of information contained in an image is often much more than is necessary. Computer generated images will always be constrained by the computer's resources or the time allowed for generation. To reduce the quantity of data in a picture while preserving its apparent quality can require complex filtering of the image data. This paper presents an algorithm for reducing data in polygon based images, using different filtering techniques that take advantage of a priori knowledge as to the images' content. One technique uses a novel implementation of vertex elimination. By passing the image through a sequence of controllable filtering stages, the image is segmented into homogeneous regions, simplified, then reassembled. The amount of data representing the picture is reduced considerably while a high degree of image quality is maintained. The effects of the different filtering stages will be analyzed with regard to data reduction and picture quality as it relates to flight simulation imagery. Numeri­ cal results are included in the analysis. Further applications of the algorithm are discussed as well.

Thesis(M. Tech.) - Central University of Technology, Free State, 2004 / Growing markets leads to an increase in production. In these modern industries, weight measurement is of high priority. Weight measurement instrumentation is used for quality control, as well as for effective process control. Ineffective instrumentation with inaccurate data will influence the production process and profit margins negatively. Experimental data is gathered from an angled load cell, placed as a crossover between two conveyer belts. A weight measurement instrument with the ability to acquire accurate measurement of individual, moving parts is produced with the aid of DSP techniques. This was accomplished by analyzing the frequency spectrum for the undesirable signals with the use of Wavelets transformations (WT) and Fourier transformations (FT). After these undesired signals were identified a digital filter was designed to remove the undesired signals. Repetition of performance is achieved by the automatic zeroing of the instrument after every individual measurement. This weight measurement instrumentation also has the ability to store data consisting of the amount of objects and their individual weights. This instrument can also determine the material of which an object is made of. This is done by calculating the friction coefficient. This function has the ability to effectively identify between iron and rubber components irrespective of their mass or area.

Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2005. / A switching state substitution must be developed that will make use of both single-phase redundancies and three-phase redundancies in the flying-capacitor topology. Losses should be taken into consideration and the algorithm must be designed for implementation on the existing PEC33 system, with on-board DSP (TMS320VC33) and FPGA (EP1K50QC208). The specific power-electronics application is a medium-voltage active filter. Existing capacitor voltage stabilisation schemes are investigated and a capacitor-voltage based algorithm is developed that is investigated in parallel with the Donzel and Bornard algorithm. Detailed simulation models are built for the evaluation of both existing and the proposed algorithm. Three-phase control is also evaluated. Timing analysis of the proposed algorithm shows that a DSP-only implementation of the proposed capacitor-based solution is not feasible. Detail design of the digital controller hereof is implemented in VHDL. Finally, a four-cell controller is fitted into the FPGA. A scalable hardware sorting architecture is utilised.

The thesis covers a series of PC programs that we have written that will enable users to easily design FIR linear phase lowpass digital filters and multistage sampling rate conversion systems. The first program is a rewrite of the McClellanParks computer program with some slight modifications. The second program uses an algorithm proposed by Rabiner that determines the length of a lowpass digital filter. Rabiner used a formula proposed by Herrmann et al. to initially estimate the filter length in his algorithm. The formula, however, assumes unity gain. We present a modification to the formula so that the gain of the filter is normalized to accommodate filters that have a gain greater than one (as in the case of a lowpass filter used in an interpolator). We have also changed the input specifications from digital to analog. Thus, the user supplies the sampling rate, passband frequency, stopband frequency, gain, and the respective maximum band errors. The program converts the specifications to digital. Then, the program iteratively estimates the filter length and interacts with the McClellan-Parks Program to determine the actual filter length that minimizes the maximum band errors. Once the actual length is known, the filter is designed and the filter coefficients may be saved to a file. Another new finding that we present is the condition that determines when to add a lowpass filter to a multistage decimator in order to reduce the total number of filter taps required to implement the system. In a typical example, we achieved a 34% reduction in the total required number of filter taps. The third program is a new program that optimizes the design of a multistage sampling rate conversion system based upon the sum of weighted computational rates and storage requirements. It determines the optimum number of stages and the corresponding upsampling and downsampling factors of each stage of the design. It also determines the length of the required lowpass digital filters using the second program. Quantization of the filter coefficients may have a significant impact on the frequency response. Consequently, we have included a routine within our program that determines the effects of such quantization on the allowable error margins within the passband and stopband. Once the filter coefficients are calculated, they can be saved to files and used in an appropriate implementation. The only requirements of the user are the initial sampling rate, final sampling rate, passband frequency, stopband frequency, corresponding maximum errors for each band, and the weighting factors to determine the optimization factor. We also present another new program that implements a sampling rate conversion from CD (44.1 kHz) to DAT (48 kHz) for digital audio. Using the third program to design the filter coefficients, the fourth program converts an input sequence (either samples of a sine wave or a unit sample sequence) sampled at the lower rate to an output sequence sampled at the higher rate. The frequency response is then plotted and the output block may be saved to a file.