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Engineering dynamic systems or materials to respond to biological process is one of the major tasks in synthetic biology and will enable wide promising applications, such as robotics and smart medicine. Herein, a super‐soft and dynamic DNA/dopamine‐grafted‐dextran hydrogel, which shows super‐fast volume‐responsiveness with high sensitivity upon solvents with different polarities and enables creation of electric circuits in response to microbial metabolism is reported. Synergic permanent and dynamic double networks are integrated in this hydrogel. A serials of dynamic hydrogel‐based electric circuits are fabricated: 1) triggered by using water as switch, 2) triggered by using water and petroleum ether as switch pair, 3) a self‐healing electric circuit; 4) remarkably, a microbial metabolism process which produces ethanol triggering electric circuit is achieved successfully. It is envisioned that the work provides a new strategy for the construction of dynamic materials, particularly DNA‐based biomaterials; and the electric circuits will be highly promising in applications, such as soft robotics and intelligent systems., A super‐soft and dynamic DNA‐based hybrid hydrogel is reported, which shows super‐fast volume‐responsiveness with high sensitivity upon solvents with different polarities and enables creation of electric circuits in response to microbial metabolism.

O presente trabalho tem como objetivo o estudo e desenvolvimento de novas topologias baseadas no conversor boost intercalado operando no modo de condução descontínuo. Inicialmente são propostos dois novos retificadores não isolados sendo um com entrada monofásica e outro com entrada trifásica. O principal diferencial das duas novas topologias são a configuração de três níveis, reduzindo os esforços de tensão nos semicondutores. Ainda como características destaca-se a baixa ondulação da corrente de entrada e o alto fator da potência sem a necessidade de malhas de controle de corrente, uma vez que operam no modo de condução descontínuo. A forma da corrente de entrada opera como seguidora da tensão de entrada. Estes retificadores são soluções interessantes para baixas potências, frente a sua facilidade de implementação e custo reduzido. Os dois novos retificadores ainda podem ser integrados as principais células multiníveis como NPC, capacitor flutuante e associação série de conversores. Dentro da literatura, apenas trabalhos que realizaram a integração de retificadores intercalados com a célula NPC foram encontradas, assim doze novas topologias são propostas através da integração dos retificadores propostos com as células multiníveis baseadas na associação série de conversores em meia ponte, ponte completa e forward. Para as topologias em ponte completa e forward, por possuírem dois braços de comutação destaca-se a possibilidade da utilização de retificadores duplo na entrada, dividindo, além dos esforços de tensão pela configuração de três níveis, a divisão de corrente e redução dos esforços de condução. Dentro do trabalho realizou-se a análise dos retificadores não isolados, onde os principais resultados de simulação são apresentados. Um protótipo foi desenvolvido para a obtenção dos resultados experimentais. Para os retificadores integrados, em função da quantidade de topologias propostas, apenas as estruturas baseadas na associação série dos conversores meia ponte e ponte completa foram desenvolvidas, totalizando seis topologias. Entre as seis topologias integradas, a fim de não tornar o texto extenso, apenas os resultados experimentais de três são apresentados. Outro ponto de contribuição do trabalho, são as possibilidades de operação dos conversores com três diferentes modulações, sendo elas modulação PWM multifase convencional, modulação PWM assimétrica e modulação em frequência. Para a modulação PWM assimétrica podem ocorrer assimetrias de tensão nos capacitores, onde são propostas duas técnicas de equilíbrio para tal modulação. This work presents the study and development of new topologies based on interleaved boost operating in discontinuous conduction mode. Firstly, are proposed two new rectifiers, one single-phase and another three-phase, where the main differential is the three-level configuration, reducing the voltage stress across the semiconductors. Other characteristics are the low input current ripple and high-power factor without current control loop due to the discontinuous conduction mode, where the input current follows the input voltage. These rectifiers are an interesting solution for low power applications with low cost and simple implementation. The proposed rectifiers can be integrated with multilevel cells as Neutral Point Clamped (NPC), flying capacitor and series connections of converters. In literature review several works present the integration of interleaved boost with NPC cell only, thus twelve new integrated topologies are proposed in the paper based on the integration of proposed rectifiers with flying capacitor, series connection of half-bridge, series connection of full-bridge and series connection of forward converters. For the fullbridge and forward converters a double input rectifier can be used, dividing the current levels. In the paper the analysis of non-isolated converters is presented. The operation is verified by simulation and a laboratory prototype. For the integrated converters, based on half-bridge and full-bridge series connection are discussed, and experimental results are presented. The proposed converters can operate with three different modulations: classical multi-phase PWM, asymmetrical PWM and frequency modulation. For asymmetrical modulation the voltage in output capacitors are unbalanced, thus are proposed two techniques to solve this problem.

The research that studies the development of the structure of primary school students’ written arguments on science issues is particularly limited. The present paper aimed to study the effect of a teaching intervention for electric circuits on the structure of primary school students’ written arguments. Instructional material was developed based on the constructivist approach to learning with the use of science and engineering practices and was implemented with 34 students aged 11 years old. The research data included the 340 written arguments the students produced in their attempt to answer the questions included in a questionnaire, they were given before and after the teaching intervention. Data analysis was carried out by classifying the sufficiency of the components of the arguments into levels. The analysis showed that the teaching intervention significantly contributed to improving the structure of students’ written arguments.

Electrical and Telecommunication Engineering is nowadays playing a fundamental role in biomedical research and its applications. Microwave and Antenna Group at EPFL are working resolutely to help in this vital field for society, as it has been unfortunately proven once again during the sanitary crisis caused by the COVID-19 outbreak in the last months. With this final degree thesis, I have tried to make my humble contribution to this broad topic, focusing on the field of Radio Frequency Identification (RFID). To do so, the main objective of this work was to study the frequency splitting phenomenon and verify whether it is plausible to identify a 2mm electrically small passive loop antenna using another active antenna of the same characteristics. It has been found that for close distances with no dielectric boundaries (up to 2.5mm for this configuration), analysing the frequency splitting phenomenon is an effective way to correctly confirm the presence of the passive antenna (or transponder), and it is even possible to determine its distance relative to the active antenna (or reader). When a dielectric environment is added, frequency splitting can be detected as well. However, in this case, the detectable distance range decreases due to the high relative permittivity conditions. These findings lead to a feasible way to implement a low-complexity 1-bit transponder for short-range applications. La Ingeniería Eléctrica y de Telecomunicaciones tiene actualmente un papel fundamental en la investigación biomédica y sus aplicaciones. El Grupo de Microondas y Antenas de la EPFL trabaja decididamente para ayudar en este campo vital para la sociedad, como ha sido lamentablemente demostrado una vez más durante la crisis sanitaria provocada por la pandemia de COVID-19 en los últimos meses. Con esta tesis de fin de grado, he tratado de hacer mi humilde aportación a este amplio tema, centrándome en el campo de la Identificación por Radiofrecuencia (RFID). Para ello, el objetivo principal de este trabajo ha sido estudiar el fenómeno de división frecuencial (conocido en inglés como frequency splitting) y verificar si es posible identificar una antena pasiva eléctricamente pequeña del tipo espira elemental de 2 mm utilizando otra antena activa de las mismas características. Se ha encontrado que para distancias cortas sin condiciones de dieléctrico (hasta 2.5 mm para esta configuración), analizar el fenómeno de división frecuencial es una forma efectiva de confirmar correctamente la presencia de la antena pasiva (o transpondedor), e incluso es posible determinar su distancia relativa a la antena activa (o lector). Cuando se añade un entorno dieléctrico, también se puede detectar la división frecuencial, pero en distancias más limitadas para condiciones de permitividad relativa alta. Estos hallazgos conducen a una forma viable de implementar un transpondedor de 1 bit de baja complejidad para aplicaciones de corto alcance. L'Enginyeria Elèctrica i de Telecomunicacions té actualment un paper fonamental en la recerca biomèdica i les seves aplicacions. El Grup de Microones i Antenes (MAG) de l'EPFL treballa decididament per tal d'ajudar en aquesta àrea vital per al conjunt de la societat, com ha estat malauradament demostrat una vegada més durant la crisi sanitària derivada de la pandèmia causada pel COVID-19 els darrers mesos. Amb aquest treball de fi de grau, he intentat fer la meva modesta aportació a aquest ampli tema, centrant-me en el camp de la Identificació per Ràdio Freqüència (RFID). A tal efecte, el principal objectiu d'aquest treball ha estat estudiar el fenomen de la divisió freqüencial (conegut en anglès com frequency splitting) i verificar si és possible identificar una antena elèctricament petita passiva del tipus espira elemental de 2mm de diàmetre mitjançant una altra antena activa de les mateixes característiques. S'ha comprovat que per a distàncies properes sense condicions de dielèctric (fins a 2,5mm en aquesta configuració), analitzar el fenomen de divisió freqüencial és una manera eficaç de confirmar correctament la presència de l'antena passiva (o transponedor), i és fins i tot possible determinar-ne la distància respecte a l'antena activa (o lector). Quan s'hi afegeix un entorn dielèctric, el fenomen de la divisió freqüencial pot ser detectat també, encara que en distàncies més limitades en condicions de permitivitats relatives elevades. Aquests resultats porten a una implementació viable d'un detector d'un bit de baixa complexitat per a aplicacions de curt abast.

Ponencia presentada en: IEEE International Conference on Environment and Electrical Engineering and 2021 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe), del 7 al 10 de septiembre de 2021 The use of permanent magnet synchronous generators (PMSGs) with full-scale back-to-back converters is rising as a common option in wind power generation systems (WPGSs). An efficient grid integration of PMSG-WPGSs is obtained through quasi-Z-source inverter (qZSI). Simultaneously, power electronic system integration concerns related to dynamics have arisen. Power electronics reduce damping of grid-connected converters, leading to dynamic issues. Several studies focus on qZSI dynamics, but the analysis of qZSI based PMSG-WPGS dynamics to evaluate transient interactions is not yet well addressed. This paper studies a qZSI based PMSG-WPGSs small-signal state-space model for Matlab/Simulink implementation in order to study these concerns. The model is applied to investigate qZSI based PMSG-WPGS dynamic response and it allows the influence of components and parameters on system dynamics to be assessed. Eigenvalues are obtained from the state-space model in order to study qZSI based PMSG-WPGS stability and the participation factors are also analyzed to find out the most influential circuit component or control on the different eigenvalues. PSCAD/EMTDC simulations are made to test the model.

With the advancing trend towards lighter and faster rail transport, there is an increasing interest in integrating composite and advanced multifunctional materials in order to infuse smart sensing and monitoring, energy harvesting and wireless capabilities within the otherwise purely mechanical rail structures and the infrastructure. This paper presents a holistic multiphysics numerical study, across both mechanical and electrical domains, that describes an innovative technique of harvesting energy from a piezoelectric micro fiber composites (MFC) built-in composite rail chassis structure. Representative environmental vibration data measured from a rail cabin have been critically leveraged here to help predict the actual vibratory and power output behaviour under service. Time domain mean stress distribution data from the Finite Element simulation were used to predict the raw AC voltage output of the MFCs. Conditioned power output was then calculated using circuit simulation of several state-of-the-art power conditioning circuits. A peak instantaneous rectified power of 181.9mWwas obtained when eight-stage Synchronised Switch Harvesting Capacitors (SSHC) from eight embedded MFCs were located. The results showed that the harvested energy could be su cient to sustain a self-powered structural health monitoring system with wireless communication capabilities. This study serves as a theoretical foundation of scavenging for vibrational power from the ambient state in a rail environment as well as to pointing to design principles to develop regenerative and power neutral smart vehicles., peer-reviewed

Treballs Finals de Grau de Matemàtiques, Facultat de Matemàtiques, Universitat de Barcelona, Any: 2020, Director: Antoni Benseny, [en] Given an electrical circuit, formed by wires, nodes, batteries and resistors, the main goal of this work is to solve this electrical circuit. This means finding the electric current in each wire. The graph theory and its use in computer science through data structures, like trees, and hierarchical traversing algorithms, like the Breadth-first search algorithm, will be used to solve the problem. The first part of the project will intend to solve an electrical circuit using C++, the main algorithms used have been described in this paper. The second part of the project will simulate an electrical circuit using graphics and control libraries allowing to interact with the electrical circuit.

This paper deals with the realization of a five-phase cross saturating permanent magnet assisted synchronous reluctance motor (PMaSynRM) drive with vector control based on maximum torque per ampere (MTPA) and flux weakening (FW) control strategies derived from the identified flux maps originating from the finite element analysis (FEM). Tracking of the reference currents in dq1 and dq3 axes is guaranteed with the proposed approach and the voltage and current constraints are not exceeded at any working condition.

This paper characterizes the robust second-moment stability of stochastic linear systems subject to varying delays. The delays assume a particular form suitable to represent packet loss in networked control systems, under the zero-order hold feedback. The proposed robust stability condition requires checking the spectral radius of an appropriate matrix that that depends on uncertain parameters belonging to a polytope. Due to this polytope’s dependence, checking the spectral radius is difficult from the numerical viewpoint. As an attempt to solve the problem, we convert the polytope-based condition into a randomized approach. Namely, we present probability bounds that help us certificate the robust second-moment stability under high probability. A real-time electronic application illustrates the potential benefits of our approach.

Los libros y los cursos de Álgebra Abstracta (o Álgebra Moderna) definen y estudian varios tipos de estructuras algebráicas, como los grupos, los espacios vectoriales, los anillos, los ideales y los cuerpos (o campos) de racionalidad. Estas estructuras se definen y se analizan en términos de unas operaciones que se caracterizan mediante propiedades que se presentan como salidas de la nada y que en realidad son solamente inferidas por abstracción de operaciones muy conocidas en disciplinas más elementales como la Geometría Euclidiana, la Teoría de Números y el Análisis Real. Pero nada se dice allí acerca de que hay sistemas de objetos físicos con relaciones mutuas, que son modelos (o ejemplos) rigurosamente fieles de tales estructuras algebraicas. Aquí se presenta uno de tales modelos, que está constituido por una clase de objetos eléctricos llamados cuadripolos, y que pueden conectarse mutuamente en paralelo (como ejemplo de una «suma» de tales cuadripolos) y en serie (como ejemplo de un «productos entre ellos»). En este sistema, y con estas dos operaciones eléctricas, se muestra, por consideraciones eléctricas, que se puede formar un modelo eléctrico de varias estructuras algebraicas: de un grupo conmutativo, de un espacio vectorial, de un anillo de entericidad y de un campo de racionalidad.Abstract: Textbooks and courses in Abstract Algebra (or Modern Algebra) present and explain several kinds of algebraic structures -such as abelian groups, vector spaces, rings, ideals and fields– as if these were “free constructions of the human spirit”. Usually mathematicians treat these structures as defined and analyzed in terms of operations which are characterized by properties which are presented as if comming up from a theoretical and purely platonic vacuum of ideas, in spite that they have been obtained indeed by inference and abstraction from well know, concrete operations in subjects such as Euclidean Geometry, Number Theory and Real Analysis. No considerations are done in those books about the existence and knowledge of physical objects endowed with mutual linkages, which are faithful models (or examples) of such algebraic structures with their inner operations. This paper presents one of those models, consisting of a class of electrical objects, the so-called electrical quadrupoles, which may be mutually connected in parallel (representing an “addition” between them) or in series (representing a “product” between them). Analysing these systems and these electrical operations, it is shown here how to construct a model of several of the above mentioned algebraic structures.Sumário: Os livros e os cursos de Álgebra Abstrata (ou Álgebra Moderna) definem e estudam vários tipos de estruturas algebráicas, como os grupos, os espaços vetoriais, os anéis, os ideais e os corpos (ou campos) de racionalidade. Estas estruturas definem-se e analisam-se em termos de umas operações que se caracterizam mediante propriedades que se apresentam como saídas da nada e que em realidade são somente inferidas por abstração de operações muito conhecidas em disciplinas mais elementares como a Geometria Euclidiana, a Teoria de Números e a Análise Real. Mas nada se diz ali a respeito de que há sistemas de objetos físicos com relações mútuas, que são modelos (ou exemplos) rigorosamente fiéis de tais estruturas algébricas. Aqui apresenta-se um de tais modelos, que está constituído por uma classe de objetos elétricos chamados cuadripolos, e que podem ser ligado mutuamente em paralelo (como exemplo de uma “soma” de tais cuadripolos) e em série (como exemplo de um “produtos entre eles”). Em este sistema, e com estas duas operações elétricas, mostra-se, por considerações elétricas, que pode ser formado um modelo elétrico de várias estruturas algébricas: de um grupo conmutativo, de um espaço vetorial, de um anel de entericidad e de um campo de racionalidade. Los libros y los cursos de Álgebra Abstracta (o Álgebra Moderna) definen y estudian varios tipos de estructuras algebráicas, como los grupos, los espacios vectoriales, los anillos, los ideales y los cuerpos (o campos) de racionalidad. Estas estructuras se definen y se analizan en términos de unas operaciones que se caracterizan mediante propiedades que se presentan como salidas de la nada y que en realidad son solamente inferidas por abstracción de operaciones muy conocidas en disciplinas más elementales como la Geometría Euclidiana, la Teoría de Números y el Análisis Real. Pero nada se dice allí acerca de que hay sistemas de objetos físicos con relaciones mutuas, que son modelos (o ejemplos) rigurosamente fieles de tales estructuras algebraicas. Aquí se presenta uno de tales modelos, que está constituido por una clase de objetos eléctricos llamados cuadripolos, y que pueden conectarse mutuamente en paralelo (como ejemplo de una «suma» de tales cuadripolos) y en serie (como ejemplo de un «productos entre ellos»). En este sistema, y con estas dos operaciones eléctricas, se muestra, por consideraciones eléctricas, que se puede formar un modelo eléctrico de varias estructuras algebraicas: de un grupo conmutativo, de un espacio vectorial, de un anillo de entericidad y de un campo de racionalidad.Abstract: Textbooks and courses in Abstract Algebra (or Modern Algebra) present and explain several kinds of algebraic structures -such as abelian groups, vector spaces, rings, ideals and fields– as if these were “free constructions of the human spirit”. Usually mathematicians treat these structures as defined and analyzed in terms of operations which are characterized by properties which are presented as if comming up from a theoretical and purely platonic vacuum of ideas, in spite that they have been obtained indeed by inference and abstraction from well know, concrete operations in subjects such as Euclidean Geometry, Number Theory and Real Analysis. No considerations are done in those books about the existence and knowledge of physical objects endowed with mutual linkages, which are faithful models (or examples) of such algebraic structures with their inner operations. This paper presents one of those models, consisting of a class of electrical objects, the so-called electrical quadrupoles, which may be mutually connected in parallel (representing an “addition” between them) or in series (representing a “product” between them). Analysing these systems and these electrical operations, it is shown here how to construct a model of several of the above mentioned algebraic structures.Sumário: Os livros e os cursos de Álgebra Abstrata (ou Álgebra Moderna) definem e estudam vários tipos de estruturas algebráicas, como os grupos, os espaços vetoriais, os anéis, os ideais e os corpos (ou campos) de racionalidade. Estas estruturas definem-se e analisam-se em termos de umas operações que se caracterizam mediante propriedades que se apresentam como saídas da nada e que em realidade são somente inferidas por abstração de operações muito conhecidas em disciplinas mais elementares como a Geometria Euclidiana, a Teoria de Números e a Análise Real. Mas nada se diz ali a respeito de que há sistemas de objetos físicos com relações mútuas, que são modelos (ou exemplos) rigorosamente fiéis de tais estruturas algébricas. Aqui apresenta-se um de tais modelos, que está constituído por uma classe de objetos elétricos chamados cuadripolos, e que podem ser ligado mutuamente em paralelo (como exemplo de uma “soma” de tais cuadripolos) e em série (como exemplo de um “produtos entre eles”). Em este sistema, e com estas duas operações elétricas, mostra-se, por considerações elétricas, que pode ser formado um modelo elétrico de várias estruturas algébricas: de um grupo conmutativo, de um espaço vetorial, de um anel de entericidad e de um campo de racionalidade.

This paper looks at the learning of the topic of electric circuits by 17-year-old students covering an advanced level course in physics, in Malta. Even if electric circuits are taught in schools both at primary and secondary level, many researchers have reported problems related to the understanding of circuits. The ideas presented during the teaching process are described as ‘abstract’ by students and the so-called ‘simple circuit’ is seen as anything but simple. This paper reports the results of a pilot study dealing with the learning of key concepts in electric circuits, focussing mainly on potential difference in simple parallel circuits. Students’ understanding was probed using a pre-test and a posttest. Interviews were then conducted using the Predict-Observe-Explain technique to further probe understanding of parallel circuits. The study indicated that all the interviewees made a visible effort to try to correctly explain how the circuit presented to them works. Moreover, about one third of these students managed to bridge the gap between their unscientific intuitions and the scientific view. The Predict-Observe-Explain technique helped students shift their thinking towards the scientific view regarding parallel circuits. The implication is that teachers must not ignore simple but effective teaching techniques which focus on putting the responsibility of learning on the student. Choosing a teaching strategy which helps to arouse students’ curiosity by creating cognitive conflicts to make students think, leads the way to a powerful and a qualitatively enriched teaching and learning experience., peer-reviewed

The development of new academie programs must assure that the goals of the authors are taken into account by the teachers and moreover that they are followed up by pedagogical actions. This paper deals with the analysis of the teachers’ perception of the didactic contents in the basic electricity program developed at the middle school level. Semi-directive interviews performed with nine teachers seem to indicate that the teachers’ professional experience and their usual habits limit their perception of program modifications, despite their knowledge of the existing difficulties that the modifications are supposed to remedy. A discussion about how to help teachers better understand and implement the intentions of the curriculum’s authors concludes the paper., La mise en place de nouveaux programmes nécessite, de la part des enseignants, une prise en compte des intentions des rédacteurs puis une traduction de celles-ci en actes pédagogiques. Nous nous intéressons ici à la perception que les enseignants ont des intentions didactiques contenues dans le nouveau programme d’électricité de la classe de quatrième en France. Des entretiens semi-directifs, conduits avec neuf enseignants, semblent montrer que leur expérience professionnelle, leurs habitudes, limitent leur perception des nouveautés malgré une bonne connaissance des difficultés que les modifications de programme visent à résoudre. Les formes particulières de cet effet de filtrage sont analysées. On observe à ce propos qu’il peut être utile d’associer des intentions didactiques nouvelles à un objet matériel lui-même nouveau qui leur serve de support., El desarrollo de nuevos prog ramas académicos necesita que las intenciones de los redactores sean tomadas en cuenta por los enseñantes y además que ellas sean traducidas en actos pedagógicos. Nosotros nos interesamos aqui en la percepcion que los enseñantes tienen de las intenciones pedagógicas contenidas en el nuevo programa de electricidad de la clase de cuarto en Francia. Entrevistas semi-directivas conducidas con nueve enseñantes, indican que sus experiencias profesionales, sus hábitos, limitan sus percepciones de las novedades a pesar de un buen conocimiento de las dificultades que las modificaciones del programa intentan resolver. Las formas particulares de este efecto de filtro son analizadas. Se observa a este propósito que puede ser útil asociar intenciones didácticas nuevas a un objeto material nuevo que les sirva de soporte., Couchouron Monique, Viennot Laurence, Courdille Jean-Marie. Les habitudes des enseignants et les intentions didactiques des nouveaux programmes d'électricité en classe de quatrième. In: Didaskalia, n°8, 1996. Nouvelles technologies dans l'enseignement des sciences et des techniques. pp. 81-96.

The paper presents results of the analysis of the vibrational generator. The paper deals with the design of a vibrational generator that is used as a power supply for independent electric circuits. The vibrational generator can be used in the various areas, e.g. traffic, electronics, special-purpose machines, and robotics. The proposed design employs magnetic damping of the core movement. It was numerically evaluated and it was shown that it was possible to obtain significantly larger output voltage and output power than in experimental settings used previously [1].

Resumo Descreve-se neste trabalho resultados recentes, obtidos com 32 alunos do Ensino Médio a respeito de concepções alternativas sobre corrente elétrica em circuitos simples. Utilizou-se um teste de 14 itens elaborado no IF-UFRGS e validado após aplicação a alunos de engenharia da mesma universidade, em 1989. No presente experimento, 7 alunos foram selecionados para entrevistas clínicas, a partir do padrão de respostas no teste escrito. Os resultados do teste escrito foram comparados àqueles obtidos na UFRGS e analisados no contexto da literatura internacional pertinente ao tema. Confirmou-se a recorrência de concepções alternativas já amplamente relatada por autores de diversos países em diferentes continentes. As entrevistas clínicas permitiram uma investigação mais detalhada deste fenômeno e sinalizaram a necessidade de novas abordagens didáticas no ensino de circuitos elétricos. Abstract This paper describes recent results obtained with 32 students from the Middle School regarding alternative conceptions about electric current in simple circuits. A 14-item test developed at IF-UFRGS was used and validated after application to engineering students from the same university in 1989. In the present experiment, 7 students were selected for clinical interviews, from the standard of answers in the written test. The results of the written test were compared to those obtained at UFRGS and analyzed in the context of the international literature relevant to the topic. The recurrence of alternative conceptions, as observed in the present investigation, has already been widely reported by authors from different countries on different continents. The clinical interviews allowed a more detailed investigation of this phenomenon and signaled the need for new didactic approaches in the teaching of electrical circuits.

Resumo A extensão natural do cálculo diferencial, proposta inicialmente em uma troca de correspondências entre l'Hôpital e Leibniz, levou ao conceito de derivada de ordem fracionária. A aplicação da derivada fracionária permite uma melhor descrição da dinâmica de muitos sistemas reais, indo desde biossistemas até mercados financeiros, que apresentam efeitos de memória, dissipação e dimensionalidade fractal. No presente trabalho, os objetivos principais são a apresentação conceitual da derivada fracionária, algumas de suas definições tanto na forma de diferenças finitas de Grünwald-Letnikov quanto nas formas integrais de Riemann-Liouville, para posteriormente aplicá-las a problemas usuais da teoria de circuitos elétricos em circuitos do tipo RC e RL de ordem fracionária. Abstract A natural extension of differential calculus, initially proposed by l'Hôpital in a letter to Leibniz, leaded to the concept of fractional order derivatives. The application of fractional derivatives allows one to correctly describe the dynamics of many real systems, from biosystems to financial markets, where memory effects, dissipation and fractal dimensionality are present. This paper aims to present an overview of fractional derivatives and its representations, both in the form of Grünwald-Letnikov finite differences as well as in the form of Riemann-Liouville integrals, and to apply it in describing RC and RL electrical circuits of fractional order.

This paper reports the first results of an experimental research, carried out in a private school with 9th grade students, where the 4C/ID-model was used for teaching and learning electric circuits. We describe the principles and features of the instructional model, that is suitability for the teaching and learning of complex knowledge and skills and yet their permeability to develop digital educational resources and learning environments. We analyse the preliminary experimental results in terms of students’ performance (both reproduction and learning transfer), mental effort and instructional efficiency. We also suggest clues to future research.

This paper presents web-based graphical schematic editor for analysis of electric and electronic circuits. It is a JavaScript application that uses Spice OPUS and Maple with PraCAn package as a computation engine. In case of linear circuits, results can be obtained in symbolic form. Continuous-time linear and nonlinear circuits as well as periodically switched linear (PSL) circuits can be analyzed. All created circuits can be exported to various file formats for greater compatibility with documentation formats and other simulation programs. The whole system is developed at the Department of Circuit Theory, for teaching support and research.

© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. IEEE Aeronautical ground lighting (AGL) systems provide a visual reference for aircraft during airport operations. Fast detection and location of failed luminaires is an important safety concern in AGL systems. In the event of luminaire failure, AGL transformers introduce harmonic currents. Resonances can increase harmonics, worsening the problem. This paper presents analytical expressions for determining resonance frequencies in AGL systems, as well as a simple procedure based on these expressions for locating failed luminaires from measurements.

International audience; This paper presents a new method to compute upper and lower bounds of any voltage or current of an arbitrary linear electric circuit model with uncertain parameters. The bounds are in the frequency domain, and when compared to a previously proposed method, this novel approach provides a higher level of guarantee. The reason is that the bounds are not only computed for a set of fixed frequencies but also computed to a set of intervals of frequencies. The details of the proposed approach, especially the equivalent uncertain element models, are given. Additionally, tests are performed on problems with low and high number of uncertain parameters. Contrary to the classical method of Monte Carlo, the results are not based on a random choice of parameters and do not depend on the number of iterations. It is shown on an example that the classical method of Monte Carlo needs a high number of iterations to reach results in agreement with the proposed method. Then, it leads to higher computation times of several orders of magnitude.

Neste trabalho são discutidos os resultados de uma sequência didática baseada no método Peer Instruction para o ensino de circuitos elétricos, aplicada em sete turmas de ensino médio integrado a cursos técnicos. Os dados obtidos, em dois testes iguais, antes e depois da aplicação do método, foram analisados a partir do ganho normalizado ou ganho de Hake, e comparados a trabalhos na literatura nacional e internacional. Os resultados revelam que seis delas apresentaram ganhos compatíveis com aqueles esperados para turmas submetidas a estratégias de aprendizagem ativa, de acordo com a literatura nacional. Por outro lado, somente os resultados apresentados por três turmas permitiriam classificá-las como turmas em que ocorreu aprendizagem ativa, considerando valores estabelecidos na literatura internacional. Nossos resultados corroboram a ideia de que a sequência didática pode ser utilizada como mediadora da relação ensino-aprendizagem para a discussão de circuitos elétricos. In this paper the results of a didactic sequence based on the Peer Instruction method for the teaching of electrical circuits are discussed. The didactic sequence was applied in seven classes of integrated technical courses at high school level. The data obtained in two equal tests before and after the application of the method were analyzed from the normalized gain or gain of Hake, and compared with Brazilian and international literature. The results show that six of them had consistent normalized gains with those expected for classes under active learning strategies, according to the Brazilian literature. On the other hand, only the results reported by three groups allow classifying them as classes where there was active learning, considering values established in the international literature. Our results strength the idea that the teaching sequence can be used as a mediator of the teaching-learning for the discussion of electrical circuits.

Los maestros están profundamente preocupados por cómo ser más efectivos en nuestra tarea de enseñar. Debemos organizar los contenidos de nuestra área específica proporcionándoles una configuración lógica, para lo cual debemos conocer la estructura mental de los alumnos que tenemos en el aula. Debemos dar forma a esta estructura mental, de manera progresiva, para que puedan asimilar los contenidos que estamos tratando de transferir, para que el aprendizaje sea lo más significativo posible. En el modelo de aprendizaje generativo, los vínculos antes del estímulo entregado por el profesor y la información almacenada en la mente del alumno requieren un esfuerzo importante del estudiante, que debe construir nuevos significados conceptuales. Ese esfuerzo, que es extremadamente necesario para un buen aprendizaje, a veces es el ingrediente faltante para que el proceso de enseñanza-aprendizaje pueda ser asimilado correctamente. En los circuitos eléctricos, que sabemos están perfectamente controlados y descritos por la ley de Ohm's y las dos reglas de Kirchhoff's, hay dos conceptos que corresponden a las siguientes magnitudes físicas: tensión y resistencia eléctrica. Estos dos conceptos están integrados y vinculados cuando se presenta el concepto de corriente. Este concepto no está subordinado a los anteriores, tiene el mismo grado de inclusión y dá lugar a relaciones sustanciales entre los tres conceptos, materializándolo en una ley: El Ohm's, nos permite relacionar y calcular cualquiera de las tres magnitudes, dos de ellas conocidas. La corriente alterna, en la que tanto la tensión como la corriente se invierten decenas de veces por segundo, desempeña un papel importante en muchos aspectos de nuestra vida moderna, ya que se utiliza universalmente. Su característica principal es que su máximo voltaje es fácilmente modificable a través del uso de transformadores, lo que facilita enormemente su transferencia con muy pocas pérdidas. En este artículo presentamos un mapa conceptual utilizando la CmapTools para que se utilice como una nueva herramienta para analizar de manera lógica la estructura subyacente en los circuitos de corriente alterna, con el objetivo de ofrecer a los estudiantes de las especialidades de Ciencias e Ingeniería otra opción para intentar lograr un aprendizaje significativo de esta importante parte de la física. Teachers are deeply concerned on how to be more effective in our task of teaching. We must organize the contents of our specific area providing them with a logical configuration, for which we must know the mental structure of the students that we have in the classroom. We must shape this mental structure, in a progressive manner, so that they can assimilate the contents that we are trying to transfer, to make the learning as meaningful as possible. In the generative learning model, the links before the stimulus delivered by the teacher and the information stored in the mind of the learner requires an important effort by the student, who should build new conceptual meanings. That effort, which is extremely necessary for a good learning, sometimes is the missing ingredient so that the teaching-learning process can be properly assimilated. In electrical circuits, which we know are perfectly controlled and described by Ohm's law and Kirchhoff's two rules, there are two concepts that correspond to the following physical quantities: voltage and electrical resistance. These two concepts are integrated and linked when the concept of current is presented. This concept is not subordinated to the previous ones, it has the same degree of inclusiveness and gives rise to substantial relations between the three concepts, materializing it into a law: The Ohm, which allows us to relate and to calculate any of the three physical magnitudes, two of them known. The alternate current, in which both the voltage and the current are reversed dozens of times per second, plays an important role in many aspects of our modern life, because it is universally used. Its main feature is that its maximum voltage is easily modifiable through the use of transformers, which greatly facilitates its transfer with very few losses. In this paper, we present a conceptual map so that it is used as a new tool to analyze in a logical manner the underlying structure in the alternate current circuits, with the objective of providing the students from Sciences and Engineering majors with another option to try, amongst all, to achieve a significant learning of this important part of physics.

This paper presents a mixed methods study in which 77 students and 3 teachers took part, that investigated the practice of Learning by Design (LBD). The study is part of a series of studies, funded by the Netherlands Organisation for Scientific Research (NWO), that aims to improve student learning, teaching skills and teacher training. LBD uses the context of design challenges to learn, among other things, science. Previous research showed that this approach to subject integration is quite successful but provides little profit regarding scientific concept learning. Perhaps, when the process of concept learning is better understood, LBD is a suitable method for integration. Through pre- and post-exams we measured, like others, a medium gain in the mastery of scientific concepts. Qualitative data revealed important focus-related issues that impede concept learning. As a result, mainly implicit learning of loose facts and incomplete concepts occurs. More transparency of the learning situation and a stronger focus on underlying concepts should make concept learning more explicit and coherent.

This paper presents a mixed methods study in which 77 students and 3 teachers took part, that investigated the practice of Learning by Design (LBD). The study is part of a series of studies, funded by the Netherlands Organisation for Scientific Research (NWO), that aims to improve student learning, teaching skills and teacher training. LBD uses the context of design challenges to learn, among other things, science. Previous research showed that this approach to subject integration is quite successful but provides little profit regarding scientific concept learning. Perhaps, when the process of concept learning is better understood, LBD is a suitable method for integration. Through pre- and post-exams we measured, like others, a medium gain in the mastery of scientific concepts. Qualitative data revealed important focus-related issues that impede concept learning. As a result, mainly implicit learning of loose facts and incomplete concepts occurs. More transparency of the learning situation and a stronger focus on underlying concepts should make concept learning more explicit and coherent.

This paper presents a mixed methods study in which 77 students and 3 teachers took part, that investigated the practice of Learning by Design (LBD). The study is part of a series of studies, funded by the Netherlands Organisation for Scientific Research, that aims to improve student learning, teaching skills and teacher training. LBD uses the context of design challenges to learn, among other things, science. Previous research showed that this approach to subject integration is quite successful but provides little profit regarding scientific concept learning. Perhaps, when the process of concept learning is better understood, LBD is a suitable method for integration. Through pre- and post-exams we measured, like others, a medium gain in the mastery of scientific concepts. Qualitative data revealed important focus-related issues that impede concept learning. As a result, mainly implicit learning of loose facts and incomplete concepts occurs. More transparency of the learning situation and a stronger focus on underlying concepts should make concept learning more explicit and coherent.

Teachers are deeply concerned on how to be more effective in our task of teaching. We must organize the contents of our specific area providing them with a logical configuration, for which we must know the mental structure of the students that we have in the classroom. We must shape this mental structure, in a progressive manner, so that they can assimilate the contents that we are trying to transfer, to make the learning as meaningful as possible. In the generative learning model, the links before the stimulus delivered by the teacher and the information stored in the mind of the learner requires an important effort by the student, who should build new conceptual meanings. That effort, which is extremely necessary for a good learning, sometimes is the missing ingredient so that the teaching-learning process can be properly assimilated. In electrical circuits, which we know are perfectly controlled and described by Ohm's law and Kirchhoff's two rules, there are two concepts that correspond to the following physical quantities: voltage and electrical resistance. These two concepts are integrated and linked when the concept of current is presented. This concept is not subordinated to the previous ones, it has the same degree of inclusiveness and gives rise to substantial relations between the three concepts, materializing it into a law: The Ohm, which allows us to relate and to calculate any of the three physical magnitudes, two of them known. The alternate current, in which both the voltage and the current are reversed dozens of times per second, plays an important role in many aspects of our modern life, because it is universally used. Its main feature is that its maximum voltage is easily modifiable through the use of transformers, which greatly facilitates its transfer with very few losses. In this paper, we present a conceptual map so that it is used as a new tool to analyze in a logical manner the underlying structure in the alternate current circuits, with the objective of providing the students from Sciences and Engineering majors with another option to try, amongst all, to achieve a significant learning of this important part of physics. AB thanks the “Generalitat Valenciana” of Spain (project PROMETEOII/2015/015) and the "Vicerrectorado de Tecnologías de la Información" of the University of Alicante, Spain (project GITE-09006-UA).

This paper presents a mixed methods study in which 77 students and 3 teachers took part, that investigated the practice of Learning by Design (LBD). The study is part of a series of studies, funded by the Netherlands Organisation for Scientific Research, that aims to improve student learning, teaching skills and teacher training. LBD uses the context of design challenges to learn, among other things, science. Previous research showed that this approach to subject integration is quite successful but provides little profit regarding scientific concept learning. Perhaps, when the process of concept learning is better understood, LBD is a suitable method for integration. Through pre- and post-exams we measured, like others, a medium gain in the mastery of scientific concepts. Qualitative data revealed important focus-related issues that impede concept learning. As a result, mainly implicit learning of loose facts and incomplete concepts occurs. More transparency of the learning situation and a stronger focus on underlying concepts should make concept learning more explicit and coherent.

CAPES Esta dissertação apresenta o desenvolvimento de um conversor elevador de tensão, com possibilidade de maior ganho que o conversor boost convencional, para aplicações em condições similares e de maior potência. Apresentam-se os principais conceitos envolvendo o conversor boost e duas de suas variações: o conversor boost de três níveis e o conversor boost intercalado com duas células conversoras. São detalhadas as formas construtivas, as etapas de funcionamento, o equacionamento e os principais pontos positivos de cada conversor, de modo a se verificar os possíveis empregos na construção de um protótipo que une as suas principais vantagens. Na apresentação deste conversor são abordadas as etapas de funcionamento, o equacionamento que rege o seu projeto, as simulações obtidas através de software (PSIM), um comparativo entre os modelos de conversor boost estudados e os resultados experimentais obtidos. This paper presents the development of a boost converter with the possibility of higher gain than the conventional boost converter for applications under similar conditions and increased power. Presents the main concepts involving the boost converter and two variations: the boost converter of three levels and the boost converter interspersed with two converter cells. The breakdown mounting positions, the operating steps, the addressing and the main strengths of each converter in order to check for possible uses in the construction of a prototype joining their main advantages. In the presentation of this converter addresses the operating steps, the equation governing its design, the simulations obtained through software (PSIM), a comparison between the boost converter models studied and the experimental results.

Shortest-path problem is one of the well-known optimization problems that has been studied by many scientists in recent years. Applications of this problem such as transportation and communication are generally solved by Dijkstra's Algorithm (Labeling). In this paper, two separate scientific fields, electronics and operation research have been linked to each other and a new algorithm has been created for to find the optimization solution of a shortest- path problem by using electric networks and rules. The proposed algorithm can solve the shortest-path problem in directed graphs and no order ones, and also can solve the longest path problems in directed graphs. In this algorithm, electrical network are used in a way that the resistance value of each branch is equal to each edge weights in the shortest-path problems. Then with using Ohm Law and Kirchhaffs Voltage Law (KVL), the current in each circuit cycle is calculated. Then the branches that contain the most passing current are specified, and according to Ohm’s Law, has the lowest resistance or weight. Thus, the shortest path in the network is achieved. Advantage of this algorithm is faster convergence to the answer and less computing time than the conventional method, especially in networks with more nods. The mentioned algorithm has been described for three examples.

International audience; Arduino open-source microcontrollers are well known in sensor applications for scientific equipment and for controlling RepRap 3D printers. Recently low-cost open-source gas metal arc weld (GMAW) RepRap 3D printers have been developed. The entry-level welders used have minimal controls and therefore lack any real-time measurement of welder voltage or current. The preliminary work on process optimization of GMAW 3D printers requires a low-cost sensor and data logger system to measure welder current and voltage. This paper reports on the development of a low-cost open-source power measurement sensor system based on Arduino architecture. The sensor system was designed, built, and tested with two entry-level MIG welders. The full bill of materials and open source designs are provided. Voltage and current were measured while making stepwise adjustments to the manual voltage setting on the welder. Three conditions were tested while welding with steel and aluminum wire on steel substrates to assess the role of electrode material, shield gas, and welding velocity. The results showed that the open source sensor circuit performed as designed and could be constructed for

Neste artigo analisamos diferentes concepçõoes e raciocínios dos alunos sobre conceitos básicos envolvidos em circuitos elétricos simples, que se tornam obstáculos para a aprendizagem, e apresentamos um produto de um trabalho de pesquisa, que consiste em um conjunto de atividades de simulação e modelagem computacionais, desenvolvidas com o software Modellus, levando em conta tais dificuldades, com o objetivo de auxiliar o aluno a superá-las. In this paper we analyze different student's conceptions and reasonings regarding basic concepts involved in simple electric circuits, that become obstacles for the learning, and present a product of a research work, that consists in a set of computational modeling and simulation activities, developed with the software Modellus, taking into account such difficulties to help students to surpass them.

O presente artigo apresenta uma Maplet, programada via Maple, idealizada para obter a solução numérica, via Método das Características, de uma Equação Diferencial Parcial conhecida como Equação do Telégrafo. Este trabalho aborda, de início, algumas noções de Equações Diferenciais Parciais, segue com a apresentação do modelo de um Circuito Elétrico expresso matematicamente por meio destas equa- ções, trabalha com os conceitos necessários para entendimento desse fenômeno físico, descrevendo, passo a passo, os procedimentos que foram implementados para obter a solução numérica por meio do Método das Características; por fim, o funcionamento da Maplet desenvolvida sobre o raciocínio teórico é exposto e a solução numérica de um exemplo particular da Equação do Telégrafo é apresentada, com o auxílio da interface gráfica disponível no pacote Maple. This paper presents a Maplet, programmed via Maple, designed for the numerical solution of a Partial Differential Equation known as the Telegraph Equation by the Method of Characteristics. This work initially addresses basic notions of Partial Differential Equations and proceeds with the presentation of the model of an Electrical Circuit expressed mathematically by means of these equations, working with the concepts needed to understand this physical phenomenon, describing step by step procedures that were implemented to obtain the solution through Method of Characteristics. Finally, the functionality of the Maplet developed on theoretical reasoning is exposed and the numerical solution of a particular example of the Telegraph Equation is presented with the aid of the Maple graphical interface.

Los libros y los cursos de Álgebra Abstracta (o Álgebra Moderna) definen y estudian varios tipos de estructuras algebráicas, como los grupos, los espacios vectoriales, los anillos, los ideales y los cuerpos (o campos) de racionalidad. Estas estructuras se definen y se analizan en términos de unas operaciones que se caracterizan mediante propiedades que se presentan como salidas de la nada y que en realidad son solamente inferidas por abstracción de operaciones muy conocidas en disciplinas más elementales como la Geometría Euclidiana, la Teoría de Números y el Análisis Real. Pero nada se dice allí acerca de que hay sistemas de objetos físicos con relaciones mutuas, que son modelos (o ejemplos) rigurosamente fieles de tales estructuras algebraicas. Aquí se presenta uno de tales modelos, que está constituido por una clase de objetos eléctricos llamados cuadripolos, y que pueden conectarse mutuamente en paralelo (como ejemplo de una «suma» de tales cuadripolos) y en serie (como ejemplo de un «productos entre ellos»). En este sistema, y con estas dos operaciones eléctricas, se muestra, por consideraciones eléctricas, que se puede formar un modelo eléctrico de varias estructuras algebraicas: de un grupo conmutativo, de un espacio vectorial, de un anillo de entericidad y de un campo de racionalidad. Textbooks and courses in Abstract Algebra (or Modern Algebra) present and explain several kinds of algebraic structures -such as abelian groups, vector spaces, rings, ideals and fields- as if these were "free constructions of the human spirit". Usually mathematicians treat these structures as defined and analyzed in terms of operations which are characterized by properties which are presented as if comming up from a theoretical and purely platonic vacuum of ideas, in spite that they have been obtained indeed by inference and abstraction from well know, concrete operations in subjects such as Euclidean Geometry, Number Theory and Real Analysis. No considerations are done in those books about the existence and knowledge of physical objects endowed with mutual linkages, which are faithful models (or examples) of such algebraic structures with their inner operations. This paper presents one of those models, consisting of a class of electrical objects, the so-called electrical quadrupoles, which may be mutually connected in parallel (representing an "addition" between them) or in series (representing a "product" between them). Analysing these systems and these electrical operations, it is shown here how to construct a model of several of the above mentioned algebraic structures. Os livros e os cursos de Álgebra Abstrata (ou Álgebra Moderna) definem e estudam vários tipos de estruturas algebráicas, como os grupos, os espaços vetoriais, os anéis, os ideais e os corpos (ou campos) de racionalidade. Estas estruturas definem-se e analisam-se em termos de umas operações que se caracterizam mediante propriedades que se apresentam como saídas da nada e que em realidade são somente inferidas por abstração de operações muito conhecidas em disciplinas mais elementares como a Geometria Euclidiana, a Teoria de Números e a Análise Real. Mas nada se diz ali a respeito de que há sistemas de objetos físicos com relações mútuas, que são modelos (ou exemplos) rigorosamente fiéis de tais estruturas algébricas. Aqui apresenta-se um de tais modelos, que está constituído por uma classe de objetos elétricos chamados cuadripolos, e que podem ser ligado mutuamente em paralelo (como exemplo de uma "soma" de tais cuadripolos) e em série (como exemplo de um "produtos entre eles"). Em este sistema, e com estas duas operações elétricas, mostra-se, por considerações elétricas, que pode ser formado um modelo elétrico de várias estruturas algébricas: de um grupo conmutativo, de um espaço vetorial, de um anel de entericidad e de um campo de racionalidade.

Bu araştırmada, ilköğretim 5. sınıf öğrencilerinin ?Yaşamımızı Yönlendiren Elektrik? ünitesindeki Basit Elektrik Devreleri konusunun öğretiminde bilgisayar ile desteklenmiş yapılandırmacı öğretim modelinin öğrenci başarısı ve tutumuna etkililiği araştırılmıştır. Ayrıca uygulanan yöntemin konuyla ilgili olarak görülen kavram yanılgılarının giderilmesi açısından etkililiği de incelenmiştir.Araştırmaya İzmir ili, Konak ilçesinde bulunan iki ilköğretim okulundaki 4 sınıfta bulunan toplam 100 öğrenci katılmıştır. Bu sınıflardan ikisi araştırmanın deney grubu (50 öğrenci) olarak, diğer ikisi ise kontrol grubu (50 öğrenci) olarak belirlenmiştir. Deney grubunda bilgisayar destekli öğretim ile ders işlenirken kontrol grubunda bilgisayar kullanılmamıştır. Çalışmanın bağımlı değişkenleri akademik başarı testi puanları ve fen bilgisine karşı tutum puanlarıdır.Araştırmada kullanılan veriler araştırmacı tarafından geliştirilen başarı testi ve fen bilgisi tutum ölçeği ile toplanmıştır. Başarı testi oluşturulurken hazırlanan ön uygulama sonuçları üzerinde madde analizi yapılmış, sonucunda KR-20 değeri .89 çıkmıştır. Ayrıca uygun olmayan maddeler çıkarılmış, gerekli maddeler düzeltilmiştir.Hazırlanan test öğrencilere ön test, son test ve yaklaşık 4 hafta sonra kalıcılık testi olarak uygulanmıştır. Fen bilgisi tutum ölçeği de ön test ve son test olarak uygulanmıştır. Elde edilen veriler SPSS 17 paket programı t-testi ile sınanmış, .05 düzeyinde anlamlılığı test edilmiştir. Veriler değerlendirilirken, deney ve kontrol grubu öğrencilerinin akademik başarıları ve tutumları uygulanan öğretim yöntemine göre incelenmiştir.Araştırma sonuçlarına göre; bilgisayar destekli öğretim yönteminin, öğrencilerin akademik başarıları ve öğrenilen bilgilerin kalıcılıkları ile fen bilgisine yönelik tutumlarını olumlu yönde etkilediği görülmüştür. Bununla birlikte uygulanan yöntemin öğrencilerin sahip oldukları kavram yanılgılarının giderilmesi konusunda daha etkili olduğu ortaya çıkmıştır.Anahtar Kelimeler: Bilgisayar Destekli Öğretim, Fen ve Teknoloji, Basit Elektrik Devreleri, Kavram Yanılgıları, Tutum The purpose of this research was to investigate the effects of the computer assisted education methods on students? academic achievement and retention of knowledge on the content of ?simple electrical circuits? from 5th grade science and technology course. In addition, the effectiveness of the applied method to remove any misconceptions on the subject was also examined.The study was implemented in two different primary school and four classes in Konak, İzmir with 100 5th grade students. The examples with the traditional method (paper and pencil based) have been applied to the control group, and the computer assisted method have been applied to the experimental group.An academic achievement test of science and technology was prepared by researcher and used as a pretest before instruction, posttest after instruction and four weeks later than instruction it was used as a retention test. The pre-treatment test was applied to the 6th grade students and item analysis was made either. As a conclusion the KR-20 coefficient of the test was appeared as `.89?. The unsuitable items were eliminated and required items were corrected.The data gathered from the test were analysed by means of SPSS 17 program While evaluating data t-test was used for analyzing and the meaningfulness was tested at, .05 level.According to the survey, computer assisted teaching method, have positive effects on academic achievement and retention of knowledge. Furthermore, it was determined that the computer assisted teaching method also have positive effects on the attitudes of the students towards science. Also, it has emerged that the applied method is more effective on eliminating the problem of misconceptions.Keywords: Computer Assisted Education, Science and Technology, Simple Electrical Circuits, Misconceptions, Attitudes 104

The undesirable phenomenon of the contact bounce causes severe erosion of the contacts and, as a consequence, their electrical life and reliability are greatly reduced. On the other hand, the bounce of the armature can provoke re-opening of the contacts, even when they have already been closed. This paper deals with the elimination of the bounce in both contacts and armature of a commercial dc core contactor. This is achieved by means of a current closed-loop controller, which only uses as input the current and voltage of the contactor’s magnetizing coil. The logic control has been implemented in a low cost microcontroller. Moreover, the board control can be fed by either dc or ac, and either in 50 Hz or 60 Hz so as to extend its applicability. A set of data is obtained from the measurement of the position and velocity of the movable parts for different operating voltages, and the dynamic behavior of the contactor is discussed.

Ac-powered contactors are extensively used in industry in applications such as automatic electrical devices, motor starters, and heaters. In this work, a practical session that allows students to model and simulate the dynamic behavior of ac-powered electromechanical contactors is presented. Simulation is carried out using a rigorous parametric model of the ac contactor that avoids simplification assumptions and is thoroughly explained. The goal of this practical is to introduce students to the topic of dynamic simulation of real devices. It covers both the transient and the steady-state response of the electromechanical system under study. The proposed methodology is flexible and not particularly time-consuming, and it allows the students easily to change the electromechanical constants of the contactor they are studying. The results of the simulations were compared with experimental data acquired by the students; a close similarity between real and simulated data was observed. The Technical University of Catalonia (UPC), Spain, has incorporated the simulation methodology proposed in this paper in a practical session of an electrical engineering course.

In this paper, the performance of a self-powered unipolar gate driver supply circuit for power devices is studied, with the aim of analyzing the viability of using such circuits in high voltage applications with discrete components. A simplified model of the circuit, capturing the essential features, is proposed, from which practical design guidelines are provided to optimize the overall circuit performance. These design guidelines allow a proper component selection that can result in significant improvements in the circuit performance. Experimental results of typical parameters characterizing the turn-on and turn-off transients, including the turn-on and turnoff energy loss, are provided for a wide range of current values and different gate resistances. The results are compared to those obtained using a conventional gate driver power supply.

One of the means of protection in the case of fault in low voltage systems is automatic disconnection of supply. Automatic disconnection of supply is required where a risk of harmful pathophysiological effects on humans can arise, resulting from dangerous touch voltage. In order to fulfil this requirement, residual current devices (RCDs) are used as protective devices. In circuits with electronic equipment various frequencies and distorted earth fault current can occur. The analysis indicates that earth fault current frequency other than the rated value often causes improper operation of RCDs. In some cases the protective device cannot trip at all and thus protection against electric shock is not effective. In circuits with electronic equipment transient and steady state leakage current can occur so it causes the RCDs unwanted tripping. This paper presents special problems of selection and operation of RCDs in circuits with electronic equipment, based on the laboratory and field investigations. Išnagrinėta elektrinės įrangos apsauga nuo viršįtampių naudojant srovės nuotėkio reles. Automatiškai atjungiamos tos grandinės, kurios yra pavojingos žmogaus gyvybei. Tokiose grandinėse srovės nuotėkio relės naudojamos kaip apsauginis elementas. Elektrinėse grandinėse gali būti sukuriami pašaliniai dažniai žemės poliaus kontakto pagrindu. Dėl jų srovės nuotėkio relė veikia netinkamai. Pašalinės srovės gali būti ir trumpalaikės, ir nuolatinės; pastaruoju šiuo atveju grandinė atjungiama. Čia išnagrinėtos problemos, susijusios su srovės nuotėkio relės parinkumu ir operacijomis elektrinėse grandinėse. Atlikti tiek teoriniai, tiek praktiniai tyrimai. Описываются методы защиты устройств от сверхнапряжении. Показано, что оптимальное решение – это автоматическое отключение сети с помощью реле, когда это необходимо для обеспечения безопасности обслуживающего персонала. Предлагается, что в таких электрических цепях целесообразно использовать частоты, построенн���е на основе контакта полюса земли. Всесторонне анализируются оптимальные условия выбора режимов реле и операций в электрических цепях. Приводятся теоретические и экспериментальные результаты.

Neste artigo analisamos diferentes concepções e raciocínios dos alunos sobre conceitos básicos envolvidos em circuitos elétricos simples, que se tornam obstáculos para a aprendizagem, e apresentamos um produto de um trabalho de pesquisa, que consiste em um conjunto de atividades de simulação e modelagem computacionais, desenvolvidas com o software Modellus, levando em conta tais dificuldades, com o objetivo de auxiliar o aluno a superá-las. In this paper we analyze different student's conceptions and reasonings regarding basic concepts involved in simple electric circuits, that become obstacles for the learning, and present a product of a research work, that consists in a set of computational modeling and simulation activities, developed with the software Modellus, taking into account such difficulties to help students to surpass them.

The purpose of this paper is to bring the attention of the control community some of the aspects of the practically important, and mathematically challenging, power factor compensation problem. Our main contribution is identifying the key role played by cyclo-dissipativity in the solution of the problem. Namely, we prove that a necessary condition for a (shunt) compensator to improve the power transfer is that the load satisfies a given cyclo-dissipativity property, which naturally leads to a formulation of the compensation problem as one of cyclo-dissipasivation. Cyclo-dissipativity systems exhibit a net absorption of (abstract) energy only along closed paths, while a dissipative system cannot create energy for all trajectories, henceforth, this concept generalizes the one of passivation

DC/AC converters with high-frequency isolation and bidirectional power flow are extensively used in photovoltaic power systems and small isolated power converters at low and medium power ranges. The main disadvantages of these circuits are: high freewheeling loss of the primary leakage current, limited ZVS range for the lagging leg switches, the effects of the parasitic elements of the systems and others. To avoid these losses an energy recovery circuit based on an active voltage clamper is presented. The control circuit is designed having a number of soft switching transitions. The system has been verified by simulation and a prototype is being tested. In this paper we present an energy recovery system and a modulation sequence for the cycloconverter. The energy recovery system is based on an active voltage clamper; the voltage peaks energy is returned to the source. Furthermore, the presented modulation sequence is designed to have a maximum number of soft-switching transitions independent of the electric variables; which means minimum losses and independence on measurement systems limitations for modulation.

The electrical energy distribution networks need remote control systems that are centralised and integrated as far as the functions they can develop are concerned. The need for a thinking unit at the line head for managing a Supervisory Control System is unavoidable. The thinking unit (microprocessor) moreover, allows a communication network to be built up which uses the line without voltage, with a variable number of transmitter-receiver stations attached to the equipped centres, as dis cussed in this paper. This paper considers a strstegy and the execution of a Supervisory Control System which adopts a dynamic polling structure and which is believed to be more attractive and economical than that adopted by rigid network structures. The following paragraphs discuss the configuration of the Distribution Network , the aims that the Supervisory Control System must fulfil, the system functions and a transmission system description.

The single-phase rectifier filter circuits, including the half- and full-wave rectifiers with a capacitor and full-wave rectification with either a series inductor or a choke-input filter, have been analyzed taking into account the voltage drop across the tube and the transformer. In these analyses the high-vacuum thermionic diode was considered. The voltage-current characteristic curve of a diode was assumed linear, and the equivalent resistance of the tube was chosen equal to the reciprocal of the slope of the diode characteristic curve in the conducting region. For the capacitive filtering case, the equations expressing the ignition angle, the extinction angle, and the ratio of the d-c output voltage to the peak value of the applied voltage when the steady state condition is reached have been derived. It was found that these equations not only depend upon the product of the angular frequency of the applied voltage and the time constant of load circuit, but also depend on the ratio of the load resistance to the equivalent resistance of the tube and the source transformer. Most of these equations appear to be of a transcendental form, the solution of which requires either graphical or trial-and-error method. Both of these require tedious work and are time consuming with hand computations. However it is easily accomplished today by the use of an IBM 7040 computer. The calculated curves showing the variation of the ignition angle, the extinction angle, and the ratio of the d-c output voltage to the peak value of the supply-voltage for half- and full-wave rectifications were plotted with wRC as abcissa for several different values of the ratio of the load resistance to the equivalent resistance of tube and transformer. The equations derived for the direct output voltage of the rectifier circuit with either the series inductor or the choke-input filters show that they depend only on the ratio of the load resistance to the total resistance of the tube, the transformer, and the inductor. All the equations mentioned above had been experimentally verified. It is found that the calculated results checked closely with the experimental data if the equivalent resistances were properly chosen. The effect of circuit parameters on the behavior of rectifier circuits operated with three types of filters have been discussed. It becomes evident that the tube and the transformer resistance of practical circuits appears as an additional parameter which cannot be neglected in t4e analysis of the single-phase rectifier. However, inclusion of this resistance greatly complicates the analysis. The method of analysis presented in this paper may be extended to other types of rectifier circuits. Although the analysis made in this paper did not take into account all of the possible factors which may be involved in the practical circuits, nevertheless the results were presented in convenient form for practical use. M.S.

In this paper, the implementation of signal processing circuits on a novel translinear Field-Programmable Analog Array (FPAA) testchip is reported. The FPAA testchip is based on a 0.35-micron, fully CMOS translinear element, which is the core block of a reconfigurable analog cell. The FPAA embeds a 5 5 cell array. As implementation examples, a four-quadrant multiplier with five decade dynamic range and a programmable fourth-order low-pass filter with up to 7 MHz bandwidth have been mapped on the translinear FPAA. 14 cells have been used for the four-quadrant multiplier while 18 cells were needed for the fourth-order low-pass filter.