In electrical power distribution and power electronic applications, a transformer is an indispensable component which performs many functions. At its operating frequency (60/50 Hz), it is one of the most bulky and expensive components. The concept of the electronic transformer introduced previously has shown considerable reduction in size, weight, and volume by operating at a higher frequency. In this dissertation, the concept of the electronic transformer is further extended to the auto-connected phase-shifting type to reduce harmonics generated by nonlinear loads. It is shown that with the addition of primary side and secondary side AC/AC converters achieves phase-shifting. With the addition of converters, magnetic components are operated at a higher frequency to yield a smaller size and weight. Two types of auto-connected electronic transformer configurations are explored. In the first configuration, the secondary converter is eliminated and the output is suitable for rectifier type loads such as adjustable speed drives. In the second configuration, the secondary converter is added to obtain a sinusoidal phase-shifted AC output voltage. This approach is applicable in general applications. With the proposed approaches, the th and 7th harmonic in utility line currents, generated by two sets of nonlinear loads, are subtracted within the electronic transformer, thereby reducing the total harmonic distortion (THD) of the line current. The analysis and simulation results are presented. In the second part of the dissertation, the electronic transformer concept is applied to a telecommunication power supply (-48 VDC) system. The proposed approach consists of a matrix converter to convert the low frequency three-phase input AC utility to a high frequency AC output without a DC-link. The output of the matrix converter is then processed via a high frequency isolation transformer to produce -48 VDC. Digital control of the system ensures that the output voltage is regulated and the input currents are of high quality, devoid of low frequency harmonics and at near unity input power factor under varying load conditions. Due to the absence of DC-link electrolytic capacitors, the power density of the proposed rectifier is shown to be higher. Analysis, design example and experimental results are presented from a three-phase 208 V, 1.5 kW laboratory prototype converter.

Three-dimensional reconstruction of small objects has been one of the most challenging problems over the last decade. Computer graphics researchers and photography professionals have been working on improving 3D reconstruction algorithms to fit the high demands of various real life applications. In this thesis, we implemented a 3D scanner system based on fringe projection method. Two different methods have been implemented and used as the unwrapping solution in fringe projection method. A parameterization tool has been created in order to generate different fringe patterns for distinctive needs in the fringe projection method. Considering our first practical implementation (based on phase shifting and multi wavelength techniques) the number of pictures used in phase shifting method has been decreased and the effects of reducing the fringe patterns on the level of precision of the 3D model have been investigated. Optical arrangement and calibration of the system (fringe projection method) have been studied, and numerous suggestions have been proposed to improve the precision of the system. Also, an evaluation method has been implemented based on calibration techniques. The error rate on both surface and height of the 3D model compare with the object has been calculated.

This dissertation presents a quantitative phase imaging microscopy technique that combines phase-shifting interferometry with multi-wavelength optical phase unwrapping. The technique consists of a Michelson-type interferometer illuminated with any of three types of light sources; light emitting diodes, laser diodes and a ring dye laser. Interference images are obtained by using a 4-frame phase shifting method, and are combined to calculate the phase of the object surface. The 2π ambiguities are removed by repeating the experiment combining two and three different wavelengths, which yields phase images of effective wavelength much longer than the original. The resulting image is a profile of the object surface with a height resolution of several nanometers and range of several microns. To our knowledge, this is the first time that a three wavelength optical phase unwrapping method with no amplified phase noise has been presented for fullframe phase images. The results presented here are divided into three main categories based on the source of illumination; light emitting diodes, laser diodes and a ring dye laser. Results for both two-wavelength optical unwrapping and three-wavelength optical unwrapping techniques are demonstrated. The interferographic images using broadband sources such as light emitting diodes are significantly less affected by coherent noise compared to images obtained using lasers. Our results show that the three wavelength optical phase unwrapping can also be effectively applied to unwrap phase images obtained using coherent light sources such as lasers and laser diodes, without amplifying phase noise in the final phase image. We have successfully shown that our multi-wavelength phase-shifting technique extends the range free of 2π ambiguities in the phase map without using conventional computation intensive phase unwrapping methods. This phase imaging technique can be used to measure physical thickness or height of both biological and other microscopic samples, with nanometer axial resolution. An added advantage of the multi-wavelength optical phase unwrapping technique is that the beat wavelength can be tailored to match height variations of specific samples.

Among the various approaches to 3-D imaging, structured light illumination (SLI) is widely spread. SLI employs a pair of digital projector and digital camera such that the correspondences can be found based upon the projecting and capturing of a group of designed light patterns. As an active sensing method, SLI is known for its robustness and high accuracy. In this dissertation, I study the phase shifting method (PSM), which is one of the most employed strategy in SLI. And, three novel approaches in PSM have been proposed in this dissertation. First, by regarding the design of patterns as placing points in an N-dimensional space, I take the phase measuring profilometry (PMP) as an example and propose the edge-pattern strategy which achieves maximum signal to noise ratio (SNR) for the projected patterns. Second, I develop a novel period information embedded pattern strategy for fast, reliable 3-D data acquisition and reconstruction. The proposed period coded phase shifting strategy removes the depth ambiguity associated with traditional phase shifting patterns without reducing phase accuracy or increasing the number of projected patterns. Thus, it can be employed for high accuracy realtime 3-D system. Then, I propose a hybrid approach for high quality 3-D reconstructions with only a small number of illumination patterns by maximizing the use of correspondence information from the phase, texture, and modulation data derived from multi-view, PMP-based, SLI images, without rigorously synchronizing the cameras and projectors and calibrating the device gammas. Experimental results demonstrate the advantages of the proposed novel strategies for 3-D SLI systems.

This diploma thesis deals with the algorithms for signal processing in a field of a low-coherence interferometry. The introductory part is devoted to the basic principle of the low-coherence interferometry and to presenting its field of applications. The second part contains a list of selected algorithms supplemented by a description of their functionality. The procedure of experimental measurement of known surface with Michelson interferometer is described in the third part and the results obtained for particular algorithms are presented. Finally, algorithms are compared on the basis of measurement results.

The deformation on cylindrical surfaces of holes in tensile loaded laminated composite specimens was measured using new moire interferometry techniques. These new techniques were developed and evaluated using a 7075-T6 aluminum control specimen. Grating replication techniques were developed for replicating high quality diffraction gratings onto the cylindrical surfaces of holes. Replicas of the cylindrical specimen gratings (undeformed and deformed) were fabricated onto circular steel sectors. Narrow angular regions of these sector gratings were directly evaluated in a moire interferometer. This moire interferometry approach eliminated potential sources of error associated with other moire interferometry approaches. Two composite tensile specimens, fabricated from IM7/5250-4 pre-preg with ply layups of [0₄/90₄]_3s and [+30₂/-30₂/90₄]_3s, were examined using the newly developed moire interferometry techniques. Circumferential and thickness direction displacement fringe patterns (each 3 degrees wide) were assembled into 90 degrees wide mosaics around the hole periphery for both composite specimens. Distributions of strain were calculated with high confidence on a sub-ply basis at select angular locations. Measured strain behavior was complex and displayed ply-by-ply trends. Large ply related variations in the circumferential strain were observed at certain angular locations around the periphery of the holes in both composites. Extremely large ply-by-ply variations of the shear strain were also documented in both composites. Peak values of shear strain approached 30 times the applied far-field axial strain. Post-loaded viscoelastic shearing strains were recorded that were associated with the regions of large load-induced shearing strains. Large ply-grouping related variations in the thickness direction strain were observed in the [+30₂/-30₂/90₄]_3s specimen. An important large-scale trend was observed where the thickness direction strain tended to be more tensile near the outside faces of the laminate than near the mid-ply region. The measured strains were compared with the three-dimensional analysis technique known as Spline Variational Elastic Laminate Technology (SVELT), resulting in a very close match and corroborating the usefulness of SVELT. / Ph. D.

No description available.

In this thesis, we establish the underlying research background necessary for tackling the problem of phase-shifting in the wavelet transform domain. Solving this problem is the key to reducing the redundancy and huge storage requirement in Image-Based Rendering (IBR) applications, which utilize wavelets. Image-based methods for rendering of dynamic glossy objects do not truly scale to all possible frequencies and high sampling rates without trading storage, glossiness, or computational time, while varying both lighting and viewpoint. This is due to the fact that current approaches are limited to precomputed radiance transfer (PRT), which is prohibitively expensive in terms of memory requirements when both lighting and viewpoint variation are required together with high sampling rates for high frequency lighting of glossy material. At the root of the above problem is the lack of a closed-form run-time solution to the nontrivial problem of rotating wavelets, which we solve in this thesis. We specifically target Haar wavelets, which provide the most efficient solution to solving the tripleproduct integral, which in turn is fundamental to solving the environment lighting problem. The problem is divided into three main steps, each of which provides several key theoretical contributions. First, we derive closed-form expressions for linear phase-shifting in the Haar domain for one-dimensional signals, which can be generalized to N-dimensional signals due to separability. Second, we derive closed-form expressions for linear phase-shifting for two-dimensional signals that are projected using the non-separable Haar transform. For both cases, we show that the coefficients of the shifted data can be computed solely by using the coefficients of the original data. We also derive closed-form expressions for non-integer shifts, which has not been reported before. As an application example of these results, we apply the new formulae to image shifting, rotation and interpolation, and demonstrate the superiority of the proposed solutions to existing methods. In the third step, we establish a solution for non-linear phase-shifting of two-dimensional non-separable Haar-transformed signals, which is directly applicable to the original problem of image-based rendering. Our solution is the first attempt to provide an analytic solution to the difficult problem of rotating wavelets in the transform domain.

This work deals with problems where multiple actors simultaneously take control decisions and implement the corresponding actions in large multi-area power systems. The fact that those actions take place in the same transmission grid introduces a coupling between the various decision-making problems. First, transmission constraints involving all actors' controls must be satisfied, while, second, the satisfaction of an actor's operational objective depends, in general, not only on its own actions but on the others' too. Algorithms and/or operational procedures are, thus, developed seeking to reconcile the multiple actors' simultaneous decisions. The confidentiality and operational autonomy of the actors' decision-making procedures are preserved. In particular, two specific problems leading to such a multi-actor situation have been treated. The first is drawn from a recently emerging situation, at least in Europe, where several Transmission System Operators (TSOs) have installed and/or are planning to install Phase Shifting Transformers (PSTs) in such locations in their areas that, by properly adjusting the PST phase angle settings, they can significantly control the power flows entering and exiting their systems. A general framework is proposed for the control of PSTs owned by several TSOs, taking into account their interactions. The proposed solution is the Nash equilibrium of a sequence of optimizations performed by the various TSOs, each of them taking into account the other TSOs' control settings as well as operating constraints relative to the whole system. The method is applied to a linearized network model and illustrated on the IEEE 118-bus system. The second multi-actor situation dealt with in this work stems from the recently increasing amount of discussions and efforts made towards creating the right market structures and operational practices that would facilitate a seamless inter-area trade of electricity throughout large interconnections. In this respect, in accordance with European Union's goal of a fully functional Internal Electricity Market where ideally every consumer will be able to buy electric energy from every producer all across the interconnection, the possibility of every market participant to place its bid in whatever electricity market of an interconnection has been considered. This results in overlapping markets, each with its own schedule of power injections and withdraws, comprising buses all around the interconnection, that are cleared simultaneously by Transaction Schedulers (TSs). An iterative procedure is proposed to reconcile the various TS schedules such that congestion is managed in a fair and efficient way. The procedure converges to such schedules that the various TS market clearings are in a Nash equilibrium. The method is then extended towards several directions: enabling market participants to place their bids simultaneously in more than one TS's market, incorporating $N-1$ security constraints, allowing for joint energy-reserve dispatch, and, accounting for transmission losses. The corresponding iterative algorithms are thoroughly illustrated in detail on a 15-bus as well as the IEEE RTS-96 system.

<p>Digital fringe projection (DFP) methods are commonly used to obtain high-accuracy shape measurements of opaque, diffusely-reflective objects. While some objects may have constant texture across its surface, this is not true for all; many measured objects may have high-contrast texture caused by edges of dark- and light-colored sections of the object. In these high-contrast areas, a phase artifact has been consistently observed, which in turn creates a specific measurement error that is sometimes referred to as ``discontinuity-induced measurement artifacts" (DMA). Our study indicated that this error is most likely caused by camera defocusing, which produces a Gaussian point spread function (PSF) that is convoluted across every captured image, thus creating an phase artifact shaped like a Gaussian function. Based on this finding, this thesis outlines a method for removing this error via Gaussian curve fitting on the affected regions. These regions can be found by locating large spikes in the image intensity gradient, which directly correspond to the edge of the phase artifact, and then using a weighted least squared method to fit a Gaussian function to the affected area. We propose to use this error removal method in two ways: first, to remove errors on a checkerboard calibration target in order to increase calibration accuracy; and second, to directly remove errors in high-contrast areas in order to decrease shape measurement error. Experimental results demonstrate that the proposed method succeeds in decreasing calibration error for a checkerboard calibration target by as much as 12\%. Shape measurement experiments were not only conducted across simple, flat boards, but also more complex surfaces, such as that of a coffee mug. This thesis will show that this measurement error can be significantly decreased for both simple and complex surfaces.</p>