State-of-the art electronic systems include ever more features and gather mixed-signal subsystems, possibly from different physical domains. At the same time, cost and development time are reduced; stressing the need for an efficient design flow for fast and reliable design. The present thesis contributes to the construction of an improved design flow supported by mixed-signal hardware description languages (HDL-AMS). In a hierarchical view, the electronic systems are recursively divided into subsystems, down to basic cells and transistor level. The typical design flow results of a top-down synthesis, from the system specifications to the physical realizations, and of a bottom-up validation, from the test of the basic cells up to the test of the system. To improve the link between the technological level and the basic cells, we develop a measurement-based analog ID card which aims to optimize the analog performance and the reliability at high temperature by enabling the choice of optimal process (bulk vs. partially-depleted silicon-on-insulator (SOI) vs. fully-depleted SOI), optimal devices (e.g. multi-threshold voltages process) and optimal bias (weak vs. moderate vs. strong inversion). In the present thesis, we deal with the following analog performance parameters: gain, gain-bandwidth product, MOSFET mismatch in weak inversion and harmonic distortion of MOSFETs in triode regime. We show that SOI transistors are still advantageous over bulk in deep-submicron CMOS technologies and that short-channel SOI transistors can safely be used for mixed-signal operation up to 250°C. The analog ID card can be included in the design flow supported by HDL-AMS. Behavioral models for the basic cells are developed using such languages and further assembled into a ÄÓ modulator with continuous-time integrators as it is a good candidate for low-power consumption and operation at high temperature. The related design issues are assessed using the behavioral models and a design optimization method is presented for a key building block, an active RC integrator with passive resistors.

The presence of information and communication technologies in the field of energy is increasing every day. Smart grid subject which aims to increase the percentage of energy generation through renewable resources and to make consumers to be involved in grid actively, is gaining importance day by day. In order to provide an effcient and reliable operation of smart grid network, it is necessary to collect relevant parameters from network components via communication infrastructure and to evaluate collected information. Also, with the inclusion of distributed energy sources in the power lines, collection of relevant data becomes important in order to ensure the quality of power. In the scope of this study, to measure current parameters, two DSP based electronic circuits and necessary embedded software have been developed. Data acquisition card is a fixed device which is to be installed to a point on the power line to gather current value samples. By means of being fed through magnetic induction from the line, this part of the system could stay on-line permanently and this allows taking measurements on demand. Sampling of line current is performed through principle of magnetic induction from the line on current sensing instrument which is connected to data-acquisition part. Also by utilization of clamp-on instruments, cutting of energy lines is not needed. Samples received by control card over radio frequency or infrared communication, are evaluated with the help of Discrete Fourier Transform (DFT). Control card can show information about Root mean square (RMS) value and harmonic components of line current and total harmonics distortion (THD) on graphic LCD. Present state of the system was tested in LV and MV environments and shown to be used on distribution lines. The system presented in this study is open to improvements and suggestions to make the system to be able to work on high voltage lines are made.

Rotary draw bending, which has very good flexibility and easy tooling, is one of the most preferred bending types for tubular profiles. Cross-section distortion and the spring-back phenomena are commonly faced problems in bending processes. Spring-back is the inevitable problem that is to be solved by manufacturer, generally by overbending. For hollow tubes cross-section distortion is another difficulty since using hollow tubes results in higher strain rates and distortions. During the process the thickness of the hollow tube at the inner surface, which is contacting with the die, increases and the thickness of the tube at the outer surface decreases. Wrinkling is another important defect that occurs at the inner surface of the tube in large diameter thin walled tube bendings. This research compares the experimental results with the finite element analysis of the rotary draw bending process. The aim is to obtain bending characteristics of the two material types, SS304 and St37 and so, to reduce the number of the bending in manufacturing. The main parameters in rotary draw bending process are the bending angle, bend radius, material properties and the geometry of the tube that is to be bent. In this study, to deal with the process, two different materials, three different bending angles and three different tube geometries are used in experiments as well as in finite element analysis. In finite element analysis explicit method is used. It is seen that the experimental results are in good agreement with the numerical results.

The objective of the research presented in this dissertation is to explore the achievable dynamic range limits in high-performance RF front-ends designed using SiGe HBTs, with a focus on complementary (npn + pnp) SiGe technologies. The performance requirements of RF front-ends are high gain, high linearity, low dc power consumption, very low noise figure, and compactness. The research presented in this dissertation shows that all of these requirements can easily be met by using complementary SiGe HBTs. Thus, a strong case is made in favor of using SiGe technologies for designing high dynamic range RF front-ends. The contributions from this research are summarized as follows: 1. The first-ever comparison study and comprehensive analysis of small-signal linearity (IIP3) for npn and pnp SiGe HBTs on SOI. 2. A novel comparison of large-signal robustness of npn and pnp SiGe HBTs for use in high-performance RF front-ends. 3. A systematic and rigorous comparison of SiGe HBT compact models for high-fidelity distortion modeling. 4. The first-ever feasibility study of using weakly-saturated SiGe HBTs for use in severely power constrained RF front-ends. 5. A novel X-band Low Noise Amplifier (LNA) using weakly-saturated SiGe HBTs. 6. Design and comprehensive analysis of RF switches with enhanced large-signal linearity. 7. Development of novel methods to reduce crosstalk noise in mixed-signal circuits and the first-ever analysis of crosstalk noise across temperature. 8. Design of a very high-linearity cellular band quadrature modulator for use in base-station applications using first-generation complementary SiGe HBTs.

The advancements of computational power in low cost FPGAs are giving the opportunityto implement real-time compensation of loudspeakers and audio systems. The need for expensive commercial audio systems is reduced when the fidelity ofmuch cheaper audio systems easily can be improved by real-time compensation. The topic of this thesis is to investigate and evaluate methods for digital compensationof distortion in audio systems. More specifically, a VHDL module isimplemented to, when necessary, alleviate the problem of drastically deterioratingfidelity of the bass appearing when the input power is too high.

Error Correction and Concealment of Block Based, Motion-Compensated Temporal Prediction, Transform Coded Video David L. Robie 133 Pages Directed by Dr. Russell M. Mersereau The use of the Internet and wireless networks to bring multimedia to the consumer continues to expand. The transmission of these products is always subject to corruption due to errors such as bit errors or lost and ill-timed packets; however, in many cases, such as real time video transmission, retransmission request (ARQ) is not practical. Therefore receivers must be capable of recovering from corrupted data. Errors can be mitigated using forward error correction in the encoder or error concealment techniques in the decoder. This thesis investigates the use of forward error correction (FEC) techniques in the encoder and error concealment in the decoder in block-based, motion-compensated, temporal prediction, transform codecs. It will show improvement over standard FEC applications and improvements in error concealment relative to the Motion Picture Experts Group (MPEG) standard. To this end, this dissertation will describe the following contributions and proofs-of-concept in the area of error concealment and correction in block-based video transmission. A temporal error concealment algorithm which uses motion-compensated macroblocks from previous frames. A spatial error concealment algorithm which uses the Hough transform to detect edges in both foreground and background colors and using directional interpolation or directional filtering to provide improved edge reproduction. A codec which uses data hiding to transmit error correction information. An enhanced codec which builds upon the last by improving the performance of the codec in the error-free environment while maintaining excellent error recovery capabilities. A method to allocate Reed-Solomon (R-S) packet-based forward error correction that will decrease distortion (using a PSNR metric) at the receiver compared to standard FEC techniques. Finally, under the constraints of a constant bit rate, the tradeoff between traditional R-S FEC and alternate forward concealment information (FCI) is evaluated. Each of these developments is compared and contrasted to state of the art techniques and are able to show improvements using widely accepted metrics. The dissertation concludes with a discussion of future work.

This thesis considers the use of the tone reservation (TR) technique in orthogonal frequency division multiplexing (OFDM) systems. The nonlinear distortion is usually introduces by the high power amplifiers (HPA) used in wireless communications systems. It orders to reduce the inter-modulation distortion (IMD) in OFDM systems. In addition to the original peak-to-average power ratio (PAPR)-reduction criterion, we propose signal-to-distortion plus noise power ratio (SDNR) criterion and distortion power plus inverse of signal power (DIS) criterion. Based on these criteria, the cross-entropy (CE) algorithm is introduced to determine desired values of the peak reduction carriers (PRCs) to improve the bit error rate (BER) of nonlinearly distorted. Computational complexity is always the major concern of PAPR technique. Therefore, the real-valued PRCs and the modified transform decomposition (MTD) method are introduced here to dramatically decrease complexity of inverse fast Fourier transform (IFFT) operation with slightly performance loss. The simulation results show that the proposed criteria provide a better BER performance and a lower computational complexity.

In this dissertation, a novel scheme performing 3D reconstruction of a scene from a 2D video sequence is presented. To this aim, first, the trajectories of the salient features in the scene are determined as a sequence of displacements via Kanade-Lukas-Tomasi tracker and Kalman filter. Then, a tentative camera trajectory with respect to a metric reference reconstruction is estimated. All frame pairs are ordered with respect to their amenability to 3D reconstruction by a metric that utilizes the baseline distances and the number of tracked correspondences between the frames. The ordered frame pairs are processed via a sequential structure-from-motion algorithm to estimate the sparse structure and camera matrices. The metric and the associated reconstruction algorithm are shown to outperform their counterparts in the literature via experiments. Finally, a mesh-based, rate-distortion efficient representation is constructed through a novel procedure driven by the error between a target image, and its prediction from a reference image and the current mesh. At each iteration, the triangular patch, whose projection on the predicted image has the largest error, is identified. Within this projected region and its correspondence on the reference frame, feature matches are extracted. The pair with the least conformance to the planar model is used to determine the vertex to be added to the mesh. The procedure is shown to outperform the dense depth-map representation in all tested cases, and the block motion vector representation, in scenes with large depth range, in rate-distortion sense.

Bending process is an important forming process in most industrial fields. Springback and cross-section distortion are commonly faced problems in bending process. Springback behavior of closed and open section beams changes with different parameters such as cross-section type, cross-section dimensions, bend radius and bend angle. For closed sections like tube, the dominating problem is cross-section distortion. The thickness of the tube at intrados (inner surface of tube being in contact with die) increases, whereas the thickness of the tube at extrados (outer surface of tube) decreases. Furthermore, another cross-section distortion type for tubes is flattening at extrados which is undesirable in some manufacturing operations. The present research, using finite element method, focuses on investigating the springback behavior of commonly used aluminum beams which are T-Shaped, U-Shaped and tubular for different cases. A series of analyses is performed for a beam and the changing parameters in the analyses are bend radius and thickness. Furthermore, for tubes, the effects of axial force on springback behavior are investigated. It is seen that the axial force causes stretching and the springback angles are decreased. Moreover, in order to overcome cross-section distortion in flattening for tubes, different internal pressures are used and the effects of internal pressure are investigated. By applying appropriate internal pressure, the flattening distortion is mostly eliminated. Conclusions are drawn revealing springback behaviors and cross-section distortions with respect to bend radius, bend angle, thickness, axial pull and internal pressures. They are in good agreement with other published researches and experimental results. Therefore, the models can be used to evaluate tooling and process design in bending operations.

Abstract The objective of this thesis is to perform the AC/DC load flow and harmonic analysis for the power supply system of mass rapid transit (MRT) system. According to the computer simulation of stochastic harmonic load flow analysis, the mean value and standard deviation of voltage harmonic distortion are derived. The mitigation of harmonic distortion has been proposed by the proper design of harmonic filter. The mathematical model of 12 pulse uncontrolled rectifiers without interphase transformers is derived and applied in the AC/DC load flow analysis. The system voltage profiles and power consumption are obtained by computer simulation with the models derived. The Taipei MRT system is selected for simulation to solve the peak and off peak load of target year, bus voltage and power demand, and the harmonic current injection of traction substation. The voltage harmonic distortion is then calculated for each time snapshot according to the operation modes of all train sets on the main lines. According to the dynamic load behavior of train sets, the stochastic harmonic load flow analysis is executed to find the variation of harmonic distortion. To improve the power quality of MRT power systems, the proposed hybrid filter, which consists of both passive filter and active filter, is considered in the simulation. It is found that better distortion mitigation can be obtained with the hybrid filter by taking into account the stochastic harmonic current injection at the traction substations.