Thesis (M.S.)--Oregon State University, 1992. / Typescript (photocopy). Includes bibliographical references (leaves 82-85). Also available on the World Wide Web.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 82-83). Also available via the Internet.

Magister Educationis - MEd (Mathematics and Science Education) / The purpose of this paper is to investigate whether the teaching of electric circuits in Grade 10 Physical Sciences using a conceptual change approach would enhance learners' understanding of the concept. The conceptual change approach is a process whereby concepts and relationships between concepts change over the course of an individual's lifetime. The process whereby conceptual change occurs is of central interest in helping to understand the process of learning, and is also important when considering the design of instruction. The study was conducted at a secondary school in a small town in the Karoo. Purposive sampling was used to select the sample of a Physical Science Grade 10 class. A mixed method approach was used to observe the effectiveness of the conceptual change approach - four conditions must exist before a conceptual change is likely to occur: (1) assess learners' dissatisfaction with their existing concepts; (2) the new concept must become intelligible; (3) the new concept must appear plausible; and (4) the new concept must be fruitful. All learners' total scores for the pre-test and post-test were calculated and recorded and total scores were statistically analyzed. This study could provide means to improve science teaching and learning. The learners were assisted to discover what was not clear to them, they were encouraged towards deeper understanding and to use their own knowledge to make sense of new concepts. The conceptual change approach could be used effectively by the teachers as it will assist to remove misconceptions learners have prior to the learning of new science concepts.

Acompanha: Unidade didática: entre o mais e o menos / Este trabalho analisa a aprendizagem significativa dos conceitos elétricos de corrente, resistência, tensão e potência elétrica a partir da Abordagem POE - Predizer, Observar e Explicar (Tao e Gustone, 1999; Oliveira, 2003), Aprendizagem Significativa (Ausubel, 2003; Moreira, 1999) e a Teoria de Multimodos e Múltiplas Representações (Prain; Waldrip, 2006; Laburú et al, 2011). Assim, o objetivo foi a utilização destes fundamentos teóricos como inspiração para a criação e aplicação da sequência didática durante as aulas da Disciplina de Princípios de Eletricidade e Magnetismo. Sendo a sequência didática o produto desta pesquisa, buscou-se formular aquela a fim de propor aos alunos diversas formas de representação de um mesmo conceito, inclusive com o uso de simulador. Para tanto, empregou-se o aplicativo de simulação Kit de Circuito DC, desenvolvido pelo projeto Tecnologia no Ensino de Física (PhET), da Universidade do Colorado. O corpus desta pesquisa restringiu-se a 14 dos 28 alunos, das turmas do 3º e 4º semestre de Engenharia de Produção e 4º semestre de Engenharia Mecânica, de uma instituição de ensino particular. Para a viabilização desta pesquisa optou-se pelo tipo de pesquisa exploratória. Os dados coletados foram avaliados segundo as metodologias quantitativa e qualitativa. Como resultados, os alunos demonstraram curiosidade no uso do painel elétrico e durante o uso do simulador. Observou-se que os alunos obtiveram um ganho conceitual superior ao ensino tradicional e equivalente ao ensino interativo, tanto para a aprendizagem demonstrada pelo questionário de conhecimentos básicos e pelo teste de concepções científicas sobre corrente elétrica (Silveira et al, 1989). No entanto, no discurso teórico sobre os conceitos básicos, mesmos após as orientações, muitos alunos mantiveram em sua estrutura cognitiva a interpretação do circuito relacionada às concepções alternativas. / This work analyzes the significant learning of electrical concepts of current, resistance, voltage and electric power from the POE Approach - Predicting, Observing and Explaining (Tao and Gustone, 1999; Oliveira, 2003), Significant Learning (Ausubel, 1999) and Multimode Theory and Multiple Representations Theory (Prain, Waldrip, 2006, Laburú et al, 2011). Thus, the objective was to use these theoretical foundations as inspiration for the creation and application of the didactic sequence during the classes of the Discipline of Principles of Electricity and Magnetism. Being the didactic sequence the product of this research, we tried to formulate that one in order to propose to the students several forms of representation of the same concept, even with the use of simulator. In order to do so, the DC Circuit Kit simulation application was developed, developed by the Technology in Teaching of Physics (PhET), University of Colorado. The corpus of this research was restricted to 14 of the 28 students, from the classes of the 3rd and 4th semester of Production Engineering and the 4th semester of Mechanical Engineering, from a private educational institution. In order to make this research viable, we opted for the type of exploratory research. The data collected were evaluated according to the quantitative and qualitative methodologies. As a result, students were curious about the use of the electrical panel and during the use of the simulator. It was observed that the students obtained a conceptual gain superior to the traditional teaching and equivalent to the interactive teaching, both for the learning demonstrated by the basic knowledge questionnaire and the test of scientific conceptions about electric current (Silveira et al, 1989). However, in the theoretical discourse on the basic concepts, same after the orientations, many students maintained in their cognitive structure the interpretation of the circuit related to the alternative conceptions.

Neste trabalho foi proposto e desenvolvido um sistema de controle de suspensão veicular semi-ativa utilizando um amortecedor magneto reológico (MR). Para simulações numéricas foram considerados: um modelo de um carro completo não linear, um sistema de controle Nebuloso para determinação da força do amortecedor e um sistema para determinar a corrente elétrica aplicada no amortecedor. Os resultados das simulações numéricas demonstraram que a estratégia de controle proposto melhorou a segurança do veiculo reduzindo os deslocamentos do eixo da roda em aproximadamente 7% e o tempo de exposição do chassi as vibrações causadas por distúrbios da estrada em aproximadamente 422,56%. Com a finalidade de implementar futuramente em um amortecedor MR a estratégia de controle proposta, foi desenvolvido um protótipo do controle real, através da utilização de um sistema microprocessado usando de microcontroladores Arduino Nano V3. Para representar o amortecedor utilizou - se uma bobina elétrica, que dispõe de características reais próximas do sistema de amortecimento final. Os resultados experimentais demonstram que o protótipo desenvolvido, reproduziu com fidelidade os resultados numéricos apresentados preliminarmente com uma faixa de erro reduzida. / In this work we proposed and developed a system of control vehicular suspension, semi active, using a magneto rheological damper (MR). For the numerical simulations were considered: a model non-linear an complete car, a fuzzy control system to determine strength of the damper and a system for determining the electrical current applied the damper. The results of numerical simulations demonstrated that proposed control strategy improves the safety by the vehicle reducing the shifts the axles the wheels in approximately 7% and the time of exposure of the chassis the vibrations caused by disturbances in the road in approximately 422.56%. In order of implement in the future a proposed control on a MR damper, a prototype of the real control was developed through the use microprocessor system using microcontrollers Arduino Nano V3. For represented the damper, was used - an electrical coil, which has real characteristics near the end cushioning system. The experimental results demonstrated that the prototype developed, faithfully reproduces the numerical results presented preliminarily with reduced error band.

Acompanha: Unidade didática: entre o mais e o menos / Este trabalho analisa a aprendizagem significativa dos conceitos elétricos de corrente, resistência, tensão e potência elétrica a partir da Abordagem POE - Predizer, Observar e Explicar (Tao e Gustone, 1999; Oliveira, 2003), Aprendizagem Significativa (Ausubel, 2003; Moreira, 1999) e a Teoria de Multimodos e Múltiplas Representações (Prain; Waldrip, 2006; Laburú et al, 2011). Assim, o objetivo foi a utilização destes fundamentos teóricos como inspiração para a criação e aplicação da sequência didática durante as aulas da Disciplina de Princípios de Eletricidade e Magnetismo. Sendo a sequência didática o produto desta pesquisa, buscou-se formular aquela a fim de propor aos alunos diversas formas de representação de um mesmo conceito, inclusive com o uso de simulador. Para tanto, empregou-se o aplicativo de simulação Kit de Circuito DC, desenvolvido pelo projeto Tecnologia no Ensino de Física (PhET), da Universidade do Colorado. O corpus desta pesquisa restringiu-se a 14 dos 28 alunos, das turmas do 3º e 4º semestre de Engenharia de Produção e 4º semestre de Engenharia Mecânica, de uma instituição de ensino particular. Para a viabilização desta pesquisa optou-se pelo tipo de pesquisa exploratória. Os dados coletados foram avaliados segundo as metodologias quantitativa e qualitativa. Como resultados, os alunos demonstraram curiosidade no uso do painel elétrico e durante o uso do simulador. Observou-se que os alunos obtiveram um ganho conceitual superior ao ensino tradicional e equivalente ao ensino interativo, tanto para a aprendizagem demonstrada pelo questionário de conhecimentos básicos e pelo teste de concepções científicas sobre corrente elétrica (Silveira et al, 1989). No entanto, no discurso teórico sobre os conceitos básicos, mesmos após as orientações, muitos alunos mantiveram em sua estrutura cognitiva a interpretação do circuito relacionada às concepções alternativas. / This work analyzes the significant learning of electrical concepts of current, resistance, voltage and electric power from the POE Approach - Predicting, Observing and Explaining (Tao and Gustone, 1999; Oliveira, 2003), Significant Learning (Ausubel, 1999) and Multimode Theory and Multiple Representations Theory (Prain, Waldrip, 2006, Laburú et al, 2011). Thus, the objective was to use these theoretical foundations as inspiration for the creation and application of the didactic sequence during the classes of the Discipline of Principles of Electricity and Magnetism. Being the didactic sequence the product of this research, we tried to formulate that one in order to propose to the students several forms of representation of the same concept, even with the use of simulator. In order to do so, the DC Circuit Kit simulation application was developed, developed by the Technology in Teaching of Physics (PhET), University of Colorado. The corpus of this research was restricted to 14 of the 28 students, from the classes of the 3rd and 4th semester of Production Engineering and the 4th semester of Mechanical Engineering, from a private educational institution. In order to make this research viable, we opted for the type of exploratory research. The data collected were evaluated according to the quantitative and qualitative methodologies. As a result, students were curious about the use of the electrical panel and during the use of the simulator. It was observed that the students obtained a conceptual gain superior to the traditional teaching and equivalent to the interactive teaching, both for the learning demonstrated by the basic knowledge questionnaire and the test of scientific conceptions about electric current (Silveira et al, 1989). However, in the theoretical discourse on the basic concepts, same after the orientations, many students maintained in their cognitive structure the interpretation of the circuit related to the alternative conceptions.

Neste trabalho foi proposto e desenvolvido um sistema de controle de suspensão veicular semi-ativa utilizando um amortecedor magneto reológico (MR). Para simulações numéricas foram considerados: um modelo de um carro completo não linear, um sistema de controle Nebuloso para determinação da força do amortecedor e um sistema para determinar a corrente elétrica aplicada no amortecedor. Os resultados das simulações numéricas demonstraram que a estratégia de controle proposto melhorou a segurança do veiculo reduzindo os deslocamentos do eixo da roda em aproximadamente 7% e o tempo de exposição do chassi as vibrações causadas por distúrbios da estrada em aproximadamente 422,56%. Com a finalidade de implementar futuramente em um amortecedor MR a estratégia de controle proposta, foi desenvolvido um protótipo do controle real, através da utilização de um sistema microprocessado usando de microcontroladores Arduino Nano V3. Para representar o amortecedor utilizou - se uma bobina elétrica, que dispõe de características reais próximas do sistema de amortecimento final. Os resultados experimentais demonstram que o protótipo desenvolvido, reproduziu com fidelidade os resultados numéricos apresentados preliminarmente com uma faixa de erro reduzida. / In this work we proposed and developed a system of control vehicular suspension, semi active, using a magneto rheological damper (MR). For the numerical simulations were considered: a model non-linear an complete car, a fuzzy control system to determine strength of the damper and a system for determining the electrical current applied the damper. The results of numerical simulations demonstrated that proposed control strategy improves the safety by the vehicle reducing the shifts the axles the wheels in approximately 7% and the time of exposure of the chassis the vibrations caused by disturbances in the road in approximately 422.56%. In order of implement in the future a proposed control on a MR damper, a prototype of the real control was developed through the use microprocessor system using microcontrollers Arduino Nano V3. For represented the damper, was used - an electrical coil, which has real characteristics near the end cushioning system. The experimental results demonstrated that the prototype developed, faithfully reproduces the numerical results presented preliminarily with reduced error band.

As an additional opportunistic component to the Southern African Mag- netotelluric Experiment (SAMTEX), audio-magnetotelluric (AMT) data were acquired during the most recent phase of the experiment (Phase IV) to inves- tigate the local-scale conductivity substructure in the Otjiwarongo and Ka- tima Mulilo regions (Namibia), as to aid in the installation of high-voltage direct current (HVDC) earth electrodes that has since taken place. Both of the AMT surveys are situated close to the edge of the orogenic Neo- Proterozoic Damara Mobile Belt (DMB). Previous studies all point to the existence of a highly conductive mid-crustal zone which correlates well with the spatial location of the DMB. Two-dimensional (2D) inverse modelling of the Otjiwarongo AMT data con rms the existence of the high conductive zone at mid-crustal depths (10-15 km). The high conductivity of the DMB is explained by the presence of interconnected graphite in the marble units present. The Katima Mulilo inversion results are characterized by a con- ductive upper crustal layer that does not form part of the DMB conductive belt. It is deduced that at the uppermost subsurface Kalahari sediments are responsible for the high conductivity observed while at greater depth it is due to ironstone within the Ghanzi Group. In contrast to the conductive DMB, the lithospheric structure of the neighbouring Archaean cratons, the Congo and Kalahari, are generally found to be electrically resistive. There- fore, it is hypothesized that ground return current, if present, will ow along a path between the Otjiwarongo and Katima Mulilo regions that lies either exclusively, or almost entirely within the DMB. The hypothesis is tested by inputting a three dimensional (3D) conductivity model (calculated using available magnetotelluric (MT) data and geological information) of the re- gion into a DC resistivity forward modelling code. Forward modelling shows that the return current is only con ned to, and follows regional trends char- acteristic of, the conductive DMB for approximately 200-300 km away from the injection point, after which there is no preferential flow.

<p>Undergraduate engineering students usually face difficulties understanding electric circuit concepts. Some of those difficulties regard with misconceptions students bring into the classroom and develop during the learning process. Additionally, the increasing complexity of the topics along the fundamental electric circuits course constitutes another factor to those difficulties students experience. Another component we can add to this equation consists of the need of modernize and actualize the curriculum to meet the society’s demands of the next taskforce. Therefore, it is important to investigate the conceptual difficulties students experience when they analyze complex electric circuits. In this dissertation, I identify what those conceptual difficulties are when undergraduate sophomore engineering students attempt to analyze solid-state device circuits. The context of this research comprises a modernized version of the traditional fundamental electric circuits course. This modernized version includes DC analysis, 1^st order transient analysis, AC, and solid-state device analysis. </p> <p>This dissertation took the form of three individual but complementary studies. Each study contributes to partially answer the overall research question. However, each study answered its own research problem. The first study attempted for identifying what concepts beginning students find challenging regarding semiconductors physics, diodes, and transistors. The second study identified student’s misconceptions when they analyze two solid-state device circuits, one with a diode, and the other with a transistor. The final study looked for determining what misconceptions students use at both earlier and more advances stages along the course. This study also searched for understanding how students move through conceptual changes along the semester. </p> <p>The general findings comprise three main points. First, students bring misconceptions into the classroom probably built from their previous experiences. Second, they also can develop those misconceptions through the learning process. This is particularly key regarding the relatively new and complex topics from student’s perspectives. Finally, language plays an important role on the kind of misconceptions students develop. How students perceive the professional community use language contributes to either consolidate or modify old misconceptions or develop new ones.</p>

Switch level faults, as opposed to traditional gate level faults, can more accurately model physical faults found in an integrated circuit. However, existing fault simulation techniques have a worst-case computational complexity of O(n²), where n is the number of devices in the circuit. This paper presents a novel switch level extension to parallel fault simulation and the switch level circuit partitioning needed for parallel processing. The parallel switch level fault simulation technique uses 9-valued logic, N and P-type switch state tables, and a minimum operation in order to simulate all faults in parallel for one switch. The circuit partitioning method uses reverse level ordering, grouping, and subgrouping in order to partition transistors for parallel processing. This paper also presents an algorithm and complexity measure for parallel fault simulation as extended to the switch level. For the algorithm, the switch level fault simulation complexity is reduced to O(L²), where L is the number of levels of switches encountered when traversing from the output to the input. The complexity of the proposed algorithm is much less than that for traditional fault simulation techniques. / Ph. D.