The terminations and the joints are the basic accessories of the power cables. Power cables require electrical stress control when terminated. Since there are different types of terminations, the analysis should be done to choose the proper method for electric field control problem at the terminations. Throughout this study two different types of termination methods are investigated by using the finite element analysis program (ANSYS): Stress Controlled Termination Model with Deflector and Stress Control Tube (SCT). The results are compared with those obtained for a cable without stress control model termination. The numerical calculations are also compared with the measurements obtained by an experimental model: the electrolytic tank model.

The main purpose of this study was to develop a three-tier test for assessing ninth-grade students&rsquo / misconceptions about simple electric circuits. The first tier of an item on the test presents an ordinary multiple choice question, the second tier presents a set of reasons for the response given to the first tier, and the third tier questions if examinees are confident for their responses to the first two tiers. The study was carried in Polatli, the biggest outlying district of capital Ankara. In the light of the related literature, interviews were conducted by the researcher so as to collect information about students&rsquo / understanding of simple electric circuits. Thereby, a list of misconceptions was acquired and it was used for developing an open-ended questionnaire. Next, the questionnaire was examined by two physics teachers and an instructor from METU for establishing content validity. The questionnaire was administered to 99 ninth-grade students and their responses were categorized in the purpose of determining the distracters of the three-tier test / the Simple Electric Circuit Diagnostic Test (SECDT). At last, the SECDT was developed and administered to 124 ninth-grade students. The validity of the SECDT was established by means of quantitative methods in addition to the qualitative methods. A positive correlation coefficient was estimated between student scores and confidence levels, that is, successful students on the SECDT were more confident for their responses than unsuccessful students. This result means that the SECDT works properly, for example, students generally understood the items and found their reasoning among the distracters. Also, what items measure was investigated by means of factor analysis, and three reasonable factors were obtained. Furthermore, proportions of false positives and negatives were estimated and found as 17.47 % and 10.82 %, respectively. As well as, Cronbach alpha reliability coefficient of student scores was estimated as 0.69, but the reliability coefficient of student misconception scores was estimated as 0.33. Consequently, the SECDT scores are valid and reliable measure of students&rsquo / qualitative understanding of simple electric circuits / however, misconception scores may not be reliable.

Power distribution networks (PDNs) are conducting structures employed in semiconductor systems with the aim of providing circuits with reliable and constant operating voltage. This network has non-neglible electrical parasitics. Consequently, when digital circuits inside the chip switch, the supply voltage delivered to them does not remain ideal and exhibits spatial and temporal voltage fluctuations. These fluctuations in the supply voltage, known as the power-supply noise (PSN), can affect the functionality and the performance of modern microprocessors. The design of this PDN in the chip is an important part in ensuring power integrity. Modeling and simulation of the PSN in on-chip PDNs is important to reduce the cost of processors. These PDNs have irregular geometries, which affect the PSN. As a result, they have to be modeled. The problem sizes encountered in this simulation are usually large (on the order of millions), necessitating computationally efficient simulation approaches. Existing approaches for this simulation do not guarantee at least one of the following three required properties: computationally efficiency, accuracy, and numerically robustness. Therefore, there is a need to develop accurate, numerically robust, and efficient algorithms for this simulation. For many interconnects (e.g., transmission lines, board connectors, package PDNs), only their frequency responses and SPICE circuits (e.g., nonlinear switching drivers, equivalent circuits of interconnects) terminating them are known. These frequency responses are usually available only up to a certain maximum frequency. Simulating the electrical behavior of these systems is important for the reliable design of microprocessors and for their faster time-to-market. Because terminations can be nonlinear, a transient simulation is required. There is a need for a transient simulation of band-limited frequency-domain data characterizing a multiport passive system with SPICE circuits. The number of ports can be large (greater than or equal to 100 ports). In this simulation, unlike in traditional circuit simulators, normal properties like stability and causality of transient results are not automatically met and have to be ensured. Existing techniques for this simulation do not guarantee at least one of the following three required properties: computationally efficiency for a large number of ports, causality, and accuracy. Therefore, there is a need to develop accurate and efficient time-domain techniques for this simulation that also ensure causality. The objectives of this Ph.D. research are twofold: 1) To develop accurate, numerically robust, and computationally efficient time-domain algorithms to compute PSN in on-chip PDNs with irregular geometries. 2) To develop accurate and computationally efficient time-domain algorithms for the causal cosimulation of band-limited frequency-domain data with SPICE circuits.

Orientador: Hugo Enrique Hernandez Figueroa / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-14T12:30:52Z (GMT). No. of bitstreams: 1 Paixao_OswaldoPedreira_D.pdf: 3002384 bytes, checksum: f5a0e8e8022dabd36cfce9ffdb839f9b (MD5) Previous issue date: 2009 / Resumo: Este trabalho, tem como objetivo o desenvolvimento de novas técnicas, para análise de regime permanente não-autonoma de circuitos de alta-velocidade não-lineares em grande-escala. Para tal, é proposto um novo método do balanço harmônico (BH) fundamentado em uma eficiente metodologia de decomposição multi-níveis, que subdivide um circuito não-linear em grande escala em uma estrutura hierarquica de super-redes (SuRs) esparsamente interconectadas. Mais precisamente, em cada nível de hierarquia, o circuito é composto por SuRs intermediárias, SuRs de fundo, e redes de conexão (RCs). As SuRs de fundo são decompostas em um aglomerado de subredes não-lineares (SRNs) correspondendo a dispositivos semicondutores, que por sua vez, estão envolvidos por uma sub-rede linear (SRL). A equação de estado e de sonda das SuRs de fundo foram obtidas utilizando uma nova metodologia que combina a formulação de espaço de estado (FEE) para as SRNs com a formulação nodal modificada (FNM) para a SRL. Esta metodologia FEE/FNM produz um sistema quadrado de equações com menor tamanho possível. Para realização das conversões do sinal entre os domínios do tempo e da frequência, foram discutidas e implementadas diferentes transformadas de Fourier discreta (TFDs), para operação em regime multi-tons, incluindo sinais com modulação digital. A equação determinante do BH multi-níveis do circuito assume uma estrutura hierarquica do tipo bloco diagonal com borda , que pode ser eficientemente resolvida utilizando técnicas de processamento paralelo. A matriz jacobiana de cada SuR de fundo é processada utilizando eficientes técnicas de matrizes esparsas, junto com o conceito de espectro de derivada. Para a solução da equação determinante, foram utilizados os métodos de Newton e do tensor para problemas de pequena- e média-escala, e os métodos de Newton inexato e do tensor inexato para problemas em grande-escala. A globalização via pesquisa-em-linha com retrocedimento, foi adotada para nestes solucionadores não-lineares. Entretanto, para o método do tensor e do tensor inexato, também foi adotada a técnica de pesquisa-em-linha curvilinear. Nos métodos inexatos, técnicas de pré-condicionamento foram utilizadas, para aumentar a eficiência e a robustez do solucionador linear iterativo em subespaço de Krylov (GMRES, GMRES-Bt e TGMRES-Bt). Finalmente, a formulação proposta foi validada e a eficiência do método do tensor e do tensor inexato comparada com o método de Newton e de Newton inexato, para diferentes topologias de circuitos utilizando diodos, FETs e HBTs, e operando sob diferentes regimes de excitação multi-tons. / Abstract: This work deals with the development of new techniques for nonautonomous nonlinear steady-state analysis of high-speed large-scale integrated circuits. To this end, it is proposed a novel harmonic balance (HB) method fundamented on a efficient multi-level decomposition methodology, that divides a large-scale circuit into hierarchical structure of sparsely interconnected supernetworks (SuNs). More precisely, the circuit is composed by intermediary SuRs, bottom SuRs and connection networks (CNs). The bottom SuNs are decomposed into a cluster of nonlinear subnetworks (NSNs) corresponding to the opto-electronic semiconductor devices, which in turn, are embedded by a linear subnetwork (LSN). Multi-port elements can be included in the LSN, in order to use measured data or results from electromagnetic analysis of structures with complex geometries. The formulation of the bottom SuN state and probe equations uses an improved table-oriented statespace formulation (SSF), that produces a square system with the lowest possible size, which is equal to the number of nonlinear state-variables (branch voltages and currents) that act as argument of the fuctions representing the semiconductor devices nonlinearities. The SSF is compared with the classical modified nodal formulation (MNF). For dealing with signal timefrequency conversions, discrete Fourier transform (DFT) techniques for different multi-tone regimes are discussed, including complex digitally modulated signals. The multi-level HB determining equation of the circuit assumes a hierarchical block bordered structure that can be efficiently tackled by parallel processing techniques. The HB jacobian matrix is handled using efficient sparse matrix techniques with a proper definition of the derivatives spectra. For the solution of a large-size HB problem, we investigated the applications of inexact tensor method based on Krylov-subspace techniques. Preconditioning are used to improve the robustness of the iterative tensor solver. To determine the circuit DC regime, we employ the tensor method. We adopted the backtracking linesearch technique as a globalisation strategy. However, for the tensor method, in particular, a curvilinear linesearch was also implemented. Finally, the formulation was validated and, the tensor and inexact tensor method efficiency was compared with the Newton and inexact Newton method, respectively, for several different circuits using diodos, FETs and HBTs, and operating under different multi-tone regimes. / Doutorado / Engenharia de Telecomunicações / Doutor em Engenharia Elétrica

In this thesis, several heuristics that aim to improve the performance of parallel fault simulation for synchronous sequential circuits have been investigated. Three heuristics were incorporated into a well known parallel fault simulator called PROOFS and the efficiency of the heuristics were measured in terms of the number of faults simulated in parallel, the number of gate evaluations, and the CPU time. The three heuristics are critical path tracing, dynamic area reduction and a new heuristic called two level simulation. Critical path tracing and dynamic area reduction which have been previously proposed for combinational circuits are extended for synchronous sequential circuits in this thesis. The two level simulation that was investigated in this thesis is designed for sequential circuits. Experimental results show that critical path tracing is the most effective of the three heuristics. In addition to the three heuristics, new fault injection and fault ordering methods were suggested to improve the speed of an efficient fault simulator called HOPE. HOPE, which was developed at Virginia Tech is, an improved version of PROOFS. HOPE_NEW, which incorporates the two heuristics performs better than HOPE in the number of gate evaluations and the CPU time. HOPE_NEW is about 1.13 times faster than HOPE for the ISCAS89 benchmark circuits. For the largest circuit, the speedup is about 40 percent. / Master of Science

Practical work is regarded as an essential part of learning; hence most tertiary institutions have included a practical component in their physics courses. There is a concern about the effectiveness of the practical work in most universities. The present study is a case study that assessed the contributions of simulations on Foundation Physics students’ practical work. In assessing the contribution of simulations, two tests, Determining and Interpreting Resistive Electric Circuits Concepts Test (DIRECT) and the Test of Integrated Science Process Skills (TISP) were used. A class test, observations and worksheets from students’ practical work were analyzed and interviews with a selected group were conducted. There were 20 Foundation Physics students participating from the University of Limpopo. Results indicated that the simulations contributed positively on students’ understanding of electric circuits. However the study revealed that the students who did simulations do not differ from those who did not do the simulations with regards to the development of process skills. / Institute of Science and Technology Education / M.Sc. (Physics Education)

Dynamic Voltage Scaling (DVS) and Adaptive body bias (ABB) techniques respectively try to reduce the dynamic and static power components of an integrated circuit. Ideally, the two techniques can be combined to find the optimal operating voltages (VDD and VBB) to minimize power consumption. A combination of the DVS and ABB may warrant the circuit to operate at voltages (supply and body bias) different from the values specified by the two methods working independently. Also, this VDD and VBB values for minimal power consumption varies with the workload of the circuit. The workload can be used as an index to select the optimal VDD/VBB values to minimize the total power consumption. This paper examines the optimal voltages for minimal power operation for typical data path circuits like adders and multiply-accumulate (MAC) units across various process, voltage, and temperature conditions and under different workloads. In addition, a workload based look up table to minimize the power consumption is also proposed. Simulation results for an adder and a multiply-accumulate circuit block indicate a power saving of 12-30% over standard DVS scheme.

Practical work is regarded as an essential part of learning; hence most tertiary institutions have included a practical component in their physics courses. There is a concern about the effectiveness of the practical work in most universities. The present study is a case study that assessed the contributions of simulations on Foundation Physics students’ practical work. In assessing the contribution of simulations, two tests, Determining and Interpreting Resistive Electric Circuits Concepts Test (DIRECT) and the Test of Integrated Science Process Skills (TISP) were used. A class test, observations and worksheets from students’ practical work were analyzed and interviews with a selected group were conducted. There were 20 Foundation Physics students participating from the University of Limpopo. Results indicated that the simulations contributed positively on students’ understanding of electric circuits. However the study revealed that the students who did simulations do not differ from those who did not do the simulations with regards to the development of process skills. / Institute of Science and Technology Education / M.Sc. (Physics Education)

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis presents the development, experimentation and validation of a reliable and robust system to monitor the injector pulse generated by an Engine Control Module (ECM) and send the corresponding fueling quantity to the real-time computer in a closed loop Hardware In the Loop (HIL) bench. The system can be easily calibrated for different engine platforms as well. The fueling quantity that is being injected by the injectors is a crucial variable to run closed loop HIL simulation to carry out the performance testing of engine, aftertreatment and other components of the vehicle. This research utilized Field Programmable Gate Arrays (FPGA) and Direct Memory Access (DMA) transfer capability offered by National Instruments (NI) Compact Reconfigurable Input-Output (cRIO) to achieve high speed data acquisition and delivery. The research was conducted in three stages. The first stage was to develop the HIL bench for the research. The second stage was to determine the performance of the system with different threshold methods and different sampling speeds necessary to satisfy the required accuracy of the fueling quantity being monitored. The third stage was to study the error and its variability involved in the injected fueling quantity from pulse to pulse, from injector to injector, between real injector stators and cheaper inductor load cells emulating the injectors, over different operating conditions with full factorial design of experimentation and mixed model Analysis Of Variance (ANOVA). Different thresholds were experimented to find out the best thresholds, the Start of Injection (SOI) threshold and the End of Injection (EOI) threshold that captured the injector “ontime” with best reliability and accuracy. Experimentation has been carried out at various data acquisition rates to find out the optimum speed of data sampling rate, trading off the accuracy of fueling quantity. The experimentation found out the expected error with a system with cheaper solution as well, so that, if a test application is not sensitive to error in fueling quantity, a cheaper solution with lower sampling rate and inductors as load cells can be used. The statistical analysis was carried out at highest available sampling rate on both injectors and inductors with the best threshold method found in previous studies. The result clearly shows the factors that affect the error and the variability in the standard deviations in error; it also shows the relation with the fixed and random factors. The real-time application developed for the HIL bench is capable of monitoring the injector waveform, using any fueling ontime table corresponding to the platform being tested, and delivering the fueling quantity in real-time. The test bench made for this research is also capable of studying injectors of different types with the automated test sequence, without occupying the resource of fully capable closed loop test benches for testing the ECM unctionality.

Indiana University-Purdue University Indianapolis (IUPUI) / This thesis focuses on optimization of wind power tracking control systems in order to capture maximum wind power for the generation system. In this work, a mathematical simulation model is developed for a variable speed wind turbine power generation system. The system consists a wind turbine with necessary transmission system, and a permanent magnet synchronous generator and its vector control system. A new fuzzy based hill climbing method for power tracking control is proposed and implemented to optimize the wind power for the system under various conditions. Two existing power tracking control methods, the tip speed ratio (TSR) control method and the speed sensorless control method are also implemented with the wind power system. The computer simulations with a 5 KW wind power generation system are performed. The results from the proposed control method are compared with those obtained using the two existing methods. It is illustrated that the proposed method generally outperforms the two existing methods, especially when the operating point is far away from the maximum point. The proposed control method also has similar stable characteristic when the operating point is close to the peak point in comparison with the existing methods. The proposed fuzzy control method is computationally efficient and can be easily implemented in real-time.