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Resumen El propósito central de la investigación que se presenta en este artículo fue promover los procesos argumentativos a partir de los modelos explicativos que existen sobre el concepto de circuitos eléctricos e identificar las relaciones que se pueden establecer entre los procesos argumentativos, entendidos a partir de los niveles de argumentación, y los modelos explicativos de dicho concepto en los estudiantes de grado 11. La investigación es descriptiva-comprensiva, realizada en tres momentos: en el momento 1, de ubicación o diagnóstico, se identificaron los modelos explicativos iniciales de los estudiantes que hicieron parte de este estudio y se determinó su nivel de argumentación; en el momento 2, de desubicación o intervención, se aplicó una unidad didáctica diseñada para intervenir los niveles argumentativos y los modelos explicativos del concepto de circuitos eléctricos de los estudiantes; finalmente, en el tercer momento de reenfoque o cierre, se realizó un análisis de los cambios en los modelos explicativos y de los niveles argumentativos que utilizan para explicar el concepto sobre circuitos eléctricos después de la aplicación de la unidad didáctica. Se concluye que promover las prácticas argumentativas en el aula de ciencias, implica reconocer que la argumentación además de ser una actividad social, puede cualificar los procesos de aprendizaje de los conceptos. Abstract The central purpose of this article was to promote argumentative processes based on the explanatory models that exist on the concept of electrical circuits, identifying the relationships that can be established between argumentative processes, understood from the levels of argumentation, and the explanatory models of this concept in 11th grade students.The research is descriptive-comprehensive, carried out in three moments: at moment 1 of Location or diagnosis, the initial explanatory models of the students who were part of this study were identified and their level of argumentation was determined; at moment 2, dislocation or intervention, a didactic unit designed to intervene the argumentative levels and explanatory models of the students' concept of electrical circuits is applied; finally at moment 3 of refocusing or closure, the analysis of the changes in the models explanatory and argumentative levels used to explain the concept of electrical circuits after the application of the didactic unit. It is concluded that promoting argumentative practices in the science classroom entails recognizing that argumentation, in addition to being a social activity, can qualify the processes of learning concepts. Resumo O objetivo central desta pesquisa foi promover processos argumentativos com base nos modelos explicativos existentes no conceito de circuitos elétricos e identificar as relações que podem ser estabelecidas entre os processos argumentativos, compreendidos a partir dos níveis de argumentação, e os modelos explicativos deste conceito em alunos do 11° ano. A pesquisa é descritiva-compreensiva, realizada em três momentos: no momento 1, de Localização ou diagnóstico, foram identificados os modelos explicativos iniciais dos alunos que fizeram parte deste estudo e determinado seu nível de argumentação; no momento 2, deslocamento ou intervenção, é aplicada uma unidade didática destinada a intervir nos níveis argumentativos e modelos explicativos do conceito de circuitos elétricos dos alunos; e no momento 3, de reorientação ou fechamento, a análise das alterações nos modelos níveis explicativo e argumentativo utilizados para explicar o conceito de circuitos elétricos após a aplicação da unidade didática. Conclui-se que promover práticas argumentativas em sala de aula de ciências implica reconhecer que a argumentação, além de ser uma atividade social, pode qualificar os processos de aprendizagem de conceitos.

The awareness and use of conceptual metaphors available in ordinary language should be a relevant part of teaching strategies, yet it is still rather neglected in teacher education. With a specific activity, we integrated a class of prospective kindergarten and primary school teachers on electric circuits with a reflection on the cognitive and linguistic aspects of metaphor. To understand how effective this integration proved to be, both in terms of learning and in terms of developing teaching skills, we conducted a single case study with a mixed qualitative–quantitative methodology. Student teachers were invited to analyze and discuss expressions on electric circuits selected from those they themselves had formulated at an earlier time. Here, we present some relevant results from the analysis of the students’ elaborations, highlighting how they worked with metaphors. They demonstrated a better understanding of the subject matter and greater awareness of teaching as well, in particular for what concerns the use of language and identifying and overcoming implicit ideas.

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.

The purpose of this research is to develop, demonstrate, and characterize a novel architecture based on surface acoustic wave (SAW) devices capable of non-reciprocal propagation of forward and reverse signals. To begin, a novel topology is introduced based on asymmetrical delay lines and a current source representing a copy of the input signal. An analysis of this structure demonstrates it is capable of functioning as an isolator with the added capability of tuning the frequency response by controlling the phase relationships be- tween input signal and its copy. The structure is dependent on creating large phase shifts of 360◦ and 180◦ which is implemented in the acoustic domain. The current source functioning as a copy of the input signal is implemented by a parametric circuit. When a non-linear capacitor is pumped by a large signal at exactly twice the input signal frequency, an amplified copy of the input signal is reflected with a phase shift according to the pump signal phase due to the presence of negative resistance. This is precisely the behavior required for the topology to function. This type of parametric amplification is known as phase-coherent degenerate parametric amplifier. To investigate further, models are developed for the surface acoustic wave transducers, the non-linear capacitor, and the overall structure in Keysight’s Advanced Design Systems (ADS). Harmonic balance simulations in ADS verify the theory and demonstrate the same tunable behavior. These simulations are then used to design the SAW device and the peripheral circuitry required to match and isolate the pump signal from the input signal. The SAW device is fabricated on bulk LiN bO3 and bonded to a PCB board containing the pump circuitry. The first implementation is based on a bi-directional center transducer design and demonstrates overall functionality with limited bandwidth due to the single resonant parametric circuit design. A secondary device with a uni-directional SAW center transducer, which better matches the bandwidth of the input and output transducers, and a 2nd order resonant network result in improved performance demonstrating gain and isolation throughout the bandwidth of the SAW filter. Furthermore, the tunable aspect is also demonstrated by controlling the phase relationship between input and pump signals. This device, however, requires phase-coherence between signals and the relationship fP=2fS to be maintained. This is difficult to implement in practical systems and requires additional complicated circuitry. For this reason, a phase-incoherent version was also investigated. The addition of the uni-directional center transducer which couples the negative resistance to the acoustic waves, generates another form of asymmetry which also results in non-reciprocal propagation of forward and reverse signals. Due to its general applicability, the focus of the work is shifted to this prototype. The device is capable of functioning under different pump frequencies each with its advantages and disadvantages. For this reason, the performance both phase-coherent and incoherent modes of operation in terms of gain, isolation, noise, and linearity are characterized and understood under the lens of para- metric amplification. When compared to the state-of-the-art, the device exhibits superior performance in terms of isolation and insertion loss.

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 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.

[EN] At present, the curricular improvement carried out in the career has led to a new plan of the teaching process, in which the essentiality of the contents constitutes a fundamental aspect to reduce the training time and achieve higher levels of independence and protagonist of the student. It is also important how these contents are integrated between the different disciplines that make up the career. Correspondingly, the MES has within its premises for the elaboration of the Study Plans E “To promote the protagonist of the student in their training process”, thus arising this work where the disciplines of mathematics and electrical circuits have been integrated, developing didactic materials , such as monographs aimed at teaching - learning mathematics applied to electrical circuits on topics such as state variables and frequency method for the analysis of electrical circuits, which will not only help to improve the teaching - learning process but also to the motivation of students for the race. The research was developed in the Electrical Engineering career, for second-year students, of the Technological University of Havana, CUJAE and its results were evaluated from an interview with the students., [ES] En la actualidad el perfeccionamiento curricular realizado en la carrera de ingeniería eléctrica ha conllevado a un nuevo plan del proceso docente, en el que la esencialidad de los contenidos constituye un aspecto fundamental para reducir el tiempo de formación y lograr mayores niveles de independencia y protagonismo del estudiante. También es importante como se integran estos contenidos entre las distintas disciplinas que conforman la carrera. En correspondencia el MES tiene dentro de sus premisas para la elaboración de los Planes de estudio E “Potenciar el protagonismo del estudiante en su proceso de formación”, surgiendo así este trabajo donde se han integrado las disciplinas de matemática y circuitos eléctricos, desarrollándose materiales didácticos, como monografías dirigidos a la enseñanza–aprendizaje de la matemática aplicada a los circuitos eléctricos en temas como variables de estados y método de frecuencia para el análisis de circuitos eléctricos, lo cual no solo ayudara a mejorar el proceso de enseñanza–aprendizaje sino también a la motivación de los estudiantes por la carrera. La investigación se desarrolló en la carrera de Ingeniería Eléctrica, para estudiantes de segundo año, de la Universidad Tecnológica de la Habana, CUJAE, y sus resultados fueron evaluados a partir de entrevista a los estudiantes.

[ES] Esta tesis trata sobre la conveniencia y utilidad de que las dos leyes de Kirchhoff sean consideradas como relaciones topológicas más que como propiedades de las intensidades y de las tensiones eléctricas. Intensificando el enfoque topológico es más fácil identificar las consecuencias que derivan solo de las dos leyes, y se convierten así en una herramienta mucho más eficaz para el estudio de diferentes y muy diversos sistemas, no solo para el estudio de las redes eléctricas. Se amplía considerablemente su alcance de esta manera, incluso dentro de la propia Teoría de Circuitos.

In recent years, large amounts of fire accidents happened in countryside due to the problems of electric circuits, which adversely affect rural people's daily lives. It becomes increasingly important to solve the problems of rural electrical fire. The southwest rural area of China, where fire situation is severe and fire accidents occur frequently, is chosen to be surveyed. The situation of rural electric circuits and the strength of fire rescue in southwest countryside of China are investigated, and the fire fatalness of wood houses and the potential perils of electrical fire in rural area are presented. Finally, some suggestions on electrical fire prevention in rural area are put forward.

High performance computing is critical for the needs of scientific discovery and economic competitiveness. An extreme-scale computing system at 1000x the performance of today’s petaflop machines will exhibit massive parallelism on multiple vertical fronts, from thousands of computational units on a single processor to thousands of processors in a single data center. To facilitate such a massively-parallel extreme-scale computing, a key challenge is power. The challenge is not power associated with base computation but rather the problem of transporting data from one chip to another at high enough rates. This thesis presents architectures and techniques to achieve low power and area footprint while achieving high data rates in a dense very-short reach (VSR) chip-to-chip (C2C) communication network. High-speed serial communication operating at ultra-low supplies improves the energy-efficiency and lowers the power envelop of a system doing an exaflop of loops. One focus area of this thesis is clock synthesis for such energy-efficient interconnect applications operating at high speeds and ultra-low supplies. A sub-integer clockfrequency synthesizer is presented that incorporates a multi-phase injection-locked ring-oscillator-based prescaler for operation at an ultra-low supply voltage of 0.5V, phase-switching based programmable division for sub-integer clock-frequency synthesis, and automatic calibration to ensure injection lock. A record speed of 9GHz has been demonstrated at 0.5V in 45nm SOI CMOS. It consumes 3.5mW of power at 9.12GHz and 0.05𝑚𝑚2 of area, while showing an output phase noise of -100dBc/Hz at 1MHz offset and RMS jitter of 325fs; it achieves a net 𝐹𝑂𝑀𝐴 of -186.5 in a 45-nm SOI CMOS process. This thesis also describes a receiver with a reference-less clocking architecture for high-density VSR-C2C links. This architecture simplifies clock-tree planning in dense extreme-scaling computing environments and has high-bandwidth CDR to enable SSC for suppressing EMI and to mitigate TX jitter requirements. It features clock-less DFE and a high-bandwidth CDR based on master-slave ILOs for phase generation/rotation. The RX is implemented in 14nm CMOS and characterized at 19Gb/s. It is 1.5x faster that previous reference-less embedded-oscillator based designs with greater than 100MHz jitter tolerance bandwidth and recovers error-free data over VSR-C2C channels. It achieves a power-efficiency of 2.9pJ/b while recovering error-free data (BER< 10−12) across a 15dB loss channel. The jitter tolerance BW of the receiver is > 200MHz and the INL of the ILO-based phase-rotator (32- Steps/UI) is

Demand for wireless network capacity keeps growing exponentially every year, as a result a 1000-fold increase in data traffic is projected over the next 10 years in the context of 5G wireless networks. Solutions for delivering the 1000-fold increase in capacity fall into three main categories: deploying smaller cells, allocating more spectrum and improving spectral efficiency of wireless systems. Smaller cells at RF frequencies (1-6GHz) are unlikely to deliver the demanded capacity increase. On the other hand, millimeter-wave spectrum (frequencies over 24GHz) offers wider, multi-GHz channel bandwidths, and therefore has gained significant research interest as one of the most promising solutions to address the data traffic demands of 5G. Another disruptive technology is full-duplex which breaks a century-old assumption in wireless communication, by simultaneous transmission and reception on the same frequency channel. In doing so, full-duplex offers many benefits for wireless networks, including an immediate spectral efficiency improvement in the physical layer. Although FD promises great benefits, self-interference from the transmitter to its own receiver poses a fundamental challenge. The self-interference can be more than a billion times stronger than the desired signal and must be suppressed below the receiver noise floor. In recent years, there has been some research efforts on fully-integrated full-duplex RF transceivers, but mm-wave fully-integrated full-duplex systems, are still in their infancy. This dissertation presents novel architectures, antenna and circuit techniques to merge two exciting technologies, mm-wave and full-duplex, which can potentially offer the dual benefits of wide bandwidths and improved spectral efficiency. To this end, two different antenna interfaces, namely a wideband reconfigurable T/R antenna pair with polarization-based antenna cancellation and an mm-wave fully-integrated magnetic-free non-reciprocal circulator, are presented. The polarization-based antenna cancellation is employed in conjunction with the RF and digital cancellation to design a 60GHz full-duplex 45nm SOI CMOS transceiver with nearly 80dB self-interference suppression. The concepts and prototypes presented in this dissertation have also profound implications for emerging applications such as vehicular radars, 5G small-cell base-stations and virtual reality.

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.

Next-generation wireless communication systems put more stringent performance requirements on the wireless RF receiver circuits. Sensitivity, linearity, bandwidth and power consumption are some of the most important specifications that often face tightly coupled tradeoffs between them. To increase the data throughput, a large number of fragmented spectrums are being introduced to the wireless communication standards. Carrier aggregation technology needs concurrent communication across several non-contiguous frequency bands, which results in a rapidly growing number of band combinations. Supporting all the frequency bands and their aggregation combinations increases the complexity of the RF receivers. Highly flexible software defined radio (SDR) is a promising technology to address these applications scenarios with lower complexity by relaxing the specifications of the RF filters or eliminating them. However, there are still many technology challenges with both the receiver architecture and the circuit implementations. The performance requirements of the receivers can also vary across different application scenario and RF environments. Field-programmable dynamic performance tradeoff can potentially reduce the power consumption of the receiver. In this dissertation, we address the performance enhancement challenges in the wideband SDRs by innovations at both the circuit building block level and the receiver architecture level. A series of research projects are conducted to push the state-of-the-art performance envelope and add features such as field-programmable performance tradeoff and concurrent reception. The projects originate from the concept of thermal noise canceling techniques and further enhance the RF performance and add features for more capable SDR receivers. Four generations of prototype LNA or receiver chips are designed, and each of them pushes at least one aspect of the RF performance such as bandwidth, linearity, and NF. A noise-canceling distributed LNA breaks the tradeoff between NF and RF bandwidth by introducing microwave circuit techniques from the distributed amplifiers. The LNA architecture uniquely provides ultra high bandwidth and low NF at low frequencies. A family of field-programmable LNA realized field-programmable performance tradeoff with current-reuse programmable transconductance cells. Interferer-reflecting loops can be applied around the LNAs to improve their input linearity by rejecting the out-of-band interferers with a wideband low in- put impedance. A low noise transconductance amplifier (LNTA) that operates in class-AB-C is invented to can handle rail-to-rail out-of-band blocker without saturation. Class-AB and class-C transconductors form a composite amplifier to increase the linear range of the input voltage. A new antenna interface named frequency-translational quadrature-hybrid (FTQH) breaks the input impedance matching requirement of the LNAs by introducing quadrature hybrid couplers to the CMOS RFIC design. The FTQH receiver achieves wideband sub-1dB NF and supports scalable massive frequency-agile concurrent reception.

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 research aims to study the effect of the modification in the Building Block Shape (BBS) on the frequency response of Sierpinski three dimensional pre-fractal antenna using conventional circuit analysis. Three different shapes of BBS's are used to build the antenna. The surface current is analyzed and compared for every BBS. A simple model was devised using the nodal analysis to provide an iterative method for calculating the distribution of currents and voltages for the antenna at every node. The antennas parameters such as Y-parameter, Input Return Loss (IRL), delivered power and surface current are investigated at the first and third tuning frequencies to enhance the perspective of the BBS effect.

M.Ed. (Science Education) The purpose of this study was to investigate the use of simulations in supporting grade 10 learners from under-performing Dinaledi schools in Soweto in eliminating their misconceptions on simple electric circuits. A quasi experimental design was used in this study and 130 participants from three Dinaledi schools in Soweto formed the sample. This study commenced by exploring and identifying the misconceptions by using a validated three-tier multiple choice diagnostic questionnaire. This diagnostic questionnaire was administered as a pre-test, to identify the misconceptions. Once the misconceptions were identified, the researcher developed an intervention strategy that included the use of PhET simulations. After completing the section on electric circuits, the same diagnostic questionnaire was employed in a post-test in order to establish if the intervention was effective in promoting conceptual change in order to reduce and eventually eliminate the misconceptions. The data was captured and SPSS version 22 was used to perform descriptive statistics in order to answer the three research questions. The results from the study were compared to results from studies conducted in Canada, Cyprus, Germany, Turkey and the USA (Engelhardt & Beichner, 2004; Peşman & Eryilmaz, 2010; Taşlidere, 2013; Kapartzianis & Kriek, 2014). The findings indicated that the use of simulations as an intervention is effective in decreasing the learners’ misconceptions in the field of simple electric circuits.

Ph.D. Please refer to full text to view abstract

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.

A Mathematica ™ package is described that uses simulations and animations to illustrate key concepts in harmonic oscillation and electric circuits for students not majoring in physics or mathematics. Students are not required to know the Mathematica™ environment: a user-friendly interface with buttons functionalities and on-line help allows immediate use of the application. Students who are familiar with the programming language have the opportunity to see the set up code that is used, and they can eventually customize it. The goal of the application presented is to enhance student insight, in the spirit of learning by experimentation.

Agradecimentos: D.S.F. thanks the financial support from Conselho Nacional de Desenvolvimento Cientifico e Tecnologico-CNPq (150232/2012-8), Brazil. We thank FAPESP and CNPq for financial support through the National Institute for Science and Technology of Quantum Information (INCT-IQ) and the Optics and Photonics Research Center (CePOF) Abstract: We present a novel approach for studying the dynamics of a superconducting qubit in a cavity. We succeed in linearizing the Hamiltonian through the application of an appropriate unitary transformation followed by a rotating wave approximation (RWA). For certain values of the parameters involved, we show that it is possible to obtain a Jaynes-Cummings type Hamiltonian. As an example, we show the existence of super-revivals for the qubit inversion FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQ Aberto

We study both experimentally and theoretically the statistical properties of the energy exchanged between two electrical conductors, kept at different temperature by two different heat reservoirs, and coupled by the electric thermal noise. Such a system is ruled by the same equations as two Brownian particles kept at different temperatures and coupled by an elastic force. We measure the heat flowing between the two reservoirs, the thermodynamic work done by one part of the system on the other, and we show that these quantities exhibit a long time fluctuation theorem. Furthermore, we evaluate the fluctuating entropy, which satisfies a conservation law. These experimental results are fully justified by the theoretically analysis. Our results give more insight into the energy transfer in the famous Feymann ratchet widely studied theoretically but never in an experiment., Comment: arXiv admin note: substantial text overlap with arXiv:1301.4311

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.

M.Ing. Electromagnetic Compatibility (EMC) of electronic equipment is currently an important design parameter. Layout play a significant role in the EMC of power electronic converters. This thesis describes an investigation undertaken into the electromagnetic effects of converter layout. Typical detrimental effects identified during experimental work are presented. Possible causes for these effects are discussed. The experimental work is based on a systematic approach, which starts with a basic single switch chopper and ends in a split supply half-bridge converter. Interconnection modelling and SPICE simulations of layout affects are investigated next. The focus falls on analytical equations for extraction and simplified simulation circuits to make the process generally accessible. Typical resonant frequencies present in some of the experimental circuits are investigated with the help of analytically extracted parameters. The possibility of minimizing detrimental layout effects through impedance matching of interconnections and their terminations, is investigated next, since the previous section quantified layout parameters. Distributed vs. lumped element modelling of interconnections, and the boudary in between, are discussed. Simulation and experimental results are presented. Since maximum fuctionality and power, and minimum cost, per volume drives product development, all elements of a circuit should be investigated for the possibility of realizing secondary or even tertiary functions contributing to normal circuit operation. This is the focus of the last part of this thesis. Employing interconnections as low-pass or surge filters are investigated. Several waveforms are used to test experimental interconnection structures. Lumped and distributed modelling of these strucutres are discussed. The thesis concludes with a theoretical investigation into the possibility of dissipation of surge-energy instead of reflection utilizing interconnection-structures. One of these structures utilizes the skin- and proximity effect to realize low-pass behaviour.

M.Ing. Low profile power electronics components are currently in great demand. The rapid advances in semiconductor and micro-electronics technology during the last ten years have played a major role in the creation of this demand. These advances are in turn driven by the need for compact design in computing, communication, consumer electronic goods and control systems with direct consequences in power supply design and manufacture. The study covered by this thesis involves the design, manufacture and thermal analysis of a planar inductor, which is a typical planar power electronics component. First, a throughout literature survey of planar magnetics revealed that satisfactory experimental procedures for the thermal analysis of passive power electronic components under operating conditions representative of modern applications are seldomly applied. Secondly, a computer based field-solver program and analytical methods are used to design and analyse a planar inductor. The applicability of different methods for determination of low power loss in passive components is discussed next. Finally, an experimental method suitable for low power loss determination is proposed and investigated. This method can be used in the analysis of inductors or capacitors of different sizes. It has a wide spectrum of application due to the advantages of frequency independence and different possible power levels.

The equivalent input noise for some active circuits does not increase when the signal bandwidth increases or when some of their resistors have a larger value. This seemingly paradoxical behavior is caused by the different transfer functions for the signal and the respective noise sources associated with these resistors.

M.Ing. The focus of the project is on the design of a variable output current source applied in the testing of circuit breakers. The possibility of the use of high-frequency, switch mode converters for the application, will be investigated. The expectation is the improvement of the system currently in use, with the help of a power electronic converter. For the application, a 1 to 200A adjustable current source must be developed, which will be powered from the 220V, 50Hz network. A number of possible solutions to the problem will be investigated. One of the challenges of the project is that the output of the converter must be a current and not a voltage, which is normally the case. Based on mathematical calculations and practical results, the best possible solution to the problem is obtained. An optimum system is presented, which meets the desired specifications.

The aim of the study is to determine pre-service and high school physics teachers' ideas about simple electric circuits. In this study, a test contains eight questions related to simple electric circuits was used to the pre-service physics teachers (32 subjects) graduated from Balikesir University, Necatibey Faculty of Education, the department of physics education and working as physics teachers (25 subjects) in various High Schools in Turkey to determine their ideas about in the same subjects. As a result, it is found that, in partial, while the physics teachers have alternate conceptions about "sequential reasoning", "source of stationary current", and "current usage", the pre-service of physics teachers have unscientific ideas about "source of stationary current", "The concept of current, energy and potential differences are used one another by mistaken", "current usage" and "sequential reasoning".

Graph theory plays many important roles in modern physics and in many different contexts, spanning diverse topics such as the description of scale-free networks and the structure of the universe as a complex directed graph in causal set theory. Graph theory is also ideally suited to describe many concepts in computer science. Therefore it is increasingly important for physics students to master the basic concepts of graph theory. Here we describe a student project where we develop a computational approach to electric circuit solving which is based on graph theoretic concepts. This highly multidisciplinary approach combines abstract mathematics, linear algebra, the physics of circuits, and computer programming to reach the ambitious goal of implementing automated circuit solving.

The concepts of network of departure and padding n-port network are defined and certain important properties of these networks are stated. A necessary and sufficient criterion for the realization of the modified cut-set matrix of a resistive n-port network having a prescribed configuration is given. A new approach to the synthesis of short-circuit conductance matrix of a resistive n-port network with more than (n + 1) nodes is outlined. Necessary and sufficient conditions for the realization of the potential factor matrix of an (n + 2) node resistive n-port network are also obtained. These conditions lead to a simple test for the realizability of the modified cut-set matrix of an (n + 2) node n-port network. Examples are worked out to illustrate the application of these results. ? 1970, IEEE. All rights reserved.

This thesis focuses on incontinence nursing homes residents. As the society is aging as the population studies show, new problems are conceded: the older the population becomes, the more nursing homes are needed. One of the nursing home main care tasks is the management of the residents incontinence. Currently, the incontinence management is done manually by caregivers of the nursing home, with the delays and unnecessary checks that this process entails. So the focus of this thesis is to automatize this process with a monitoring system to support the incontinence management of the nursing homes. This project has previous stages: the sensor module that measures ambient parameters such as temperature, humidity or gas concentration, needed to evaluate that incontinence cases, is already developed. This thesis will focus on study the raw sensor data and convertit in a useful data for monitoring incontinence. As a first part, this raw data will be ordered, classified and plotted in graphs. Afterwards, a characterization of the sensors in the module will be applied in order to obtain the conversion rates that will be used to convert this data, that comes from the output of the microcontroller, into real ammounts of gas concentration. Also the measurements of the sensors need to be calibrated by programming to avoid the effects of extermal factors. Finally the results obtained in this thesis will be studied and compared with a smart incontinence application that is already on the market. Esta tesis se centra en la incontinencia de los residentes de hogares de ancianos. A medida que la sociedad envejece, como muestran los estudios de población, se necesitan más residencias de ancianos. Y una de las tareas principales de una residencia de ancianos es la gestión de la incontinencia de sus pacientes. Actualmente, el manejo de la incontinencia se realiza manualmente por los cuidadores de los residentes, con las demoras y las comprobaciones innecesarias que este proceso implica. Entonces, el enfoque de esta tesis es automatizar este proceso y hacer un sistema de monitoreo para apoyar el manejo de la incontinencia en las residencias de ancianos. Este proyecto tiene etapas previas: el módulo sensor que mide parámetros ambientales como la temperatura, la humedad o la concentración de gas, necesarios para evaluar los casos de incontinencia, ya está desarrollado. Esta tesis se centrará en estudiar los datos que provienen del módulo del sensor para convertirlos en datos útiles para la monitorización de la incontinencia. Como primera parte, estos datos sin procesar se ordenarán, clasificarán y representarán en gráficos. Posteriormente, se aplicará una caracterización de los sensores en el módulo para obtener las tasas de conversión que se utilizarán para convertir estos datos. que provienen de la salida del microcontrolador, en cantidades reales de concentración de gas. También es necesario calibrar las medidas los sensores mediante programación para evitar los efectos de hechos externos. Finalmente, los resultados obtenidos en esta tesis serán estudiados y comparados con una aplicación de detección inteligente de incontinencia que ya está en el mercado. Aquest TFG es centra en la incontinència dels residents de llars d'avis. A mesura que la societat envelleix, com mostren els estudis de població, es necessiten més residències d'ancians. I una de les tasques principals d'una residència d'ancians és la gestió de la incontinència dels seus pacients. Actualment, el maneig de la incontinència es realitza manualment pels cuidadors dels residents, amb les demores i les comprovacions innecessàries que aquest procés implica. Llavors, l'enfocament d'aquesta tesi és automatitzar aquest procés i fer un sistema de monitorització per donar suport al maneig de la incontinència en les llars d'avis. Aquest projecte té etapes prèvies: el mòdul sensor que mesura paràmetres ambientals com la temperatura, la humitat o la concentració de gas, necessaris per avaluar els casos d'incontinència, ja està desenvolupat. Aquest TFG es centrarà en estudiar les dades que provenen del mòdul del sensor per convertir-los en dades útils per a la monitorització de la incontinència. Com a primera part, aquestes dades sense processar s'ordenaran, classificaran i representaran en gràfics. Posteriorment, s'aplicarà una caracterització dels sensors en el mòdul per obtenir les taxes de conversió que s'utilitzaran per convertir aquestes dades, que provenen de la sortida del microcontrolador, en quantitats reals de concentració de gas. També cal calibrar les mesures dels sensors mitjançant programació per evitar els efectes de fets externs. Finalment, els resultats obtinguts en aquesta tesi seran estudiats i comparats amb una aplicació de detecció intel·ligent de la incontinència que ja està en el mercat.

This letter analyzes how the efficiency of boost dc/dc converters operating in burst mode under light-load conditions can be improved by an appropriate selection of the inductor current that transfers energy from the input to the output. A theoretical analysis evaluates the main power losses (fixed, conduction, and switching losses) involved in such converters, and how do they depend on the inductor current. This analysis shows that there is an optimal value of this current that causes minimum losses and, hence, maximum efficiency. These theoretical predictions are then compared with experimental data resulting from a commercial boost dc/dc converter (TPS61252), whose average inductor current is adjustable. Experimental results show that the use of the optimal inductor current, which was around 340 mA for an output voltage of 5 V, provides an efficiency increase of 7%.

En los equipos para ensayos de impulso de corriente, un parámetro fundamental para el dimensionamiento de estos es la energía aportada al ESE (Equipo Sometido a Ensayo) la cual tendrá que ser previamente almacenada en el generador. En este documento se expone el cálculo y se ofrecen unas gráficas para la determinación de los componentes del circuito generador en cada configuración de tiempos característicos en diferentes tipos de impulsos de corriente.

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.

En l’actualitat, els sistemes de control per a circuits de calderes, radiadors i aigua calenta sanitària tenen un inconvenient a l’hora d’instal·lar-los. Aquests sistemes de control, anomenats centraletes de regulació, estan dissenyats per a realitzar el control de diferents configuracions d’instal·lació, les quals incorporen diferents tipus de circuits. Cada centraleta pot fer-se càrrec d’una certa configuració de circuits i no és capaç d’adaptar-se a la instal·lació existent. Això provoca que s’hagin d’afegir més centraletes per a poder controlar aquests circuits, provocant la possibilitat de tenir centraletes amb circuits desconnectats, encarint innecessàriament la instal·lació. A l’hora de voler ampliar-la ens trobem amb el mateix problema o amb el de tenir que canviar les centraletes ja instal·lades, encarint la reforma. El propòsit d’aquest projecte ha estat dissenyar una centraleta de control modular i escalable que pugui evitar aquests dos problemes, afegint o millorant la flexibilitat i els costos d’instal·lació. Els mòduls de control d’aquesta centraleta es poden instal·lar de forma distribuïda per tota la instal·lació controlant individualment cada circuit. Els mòduls reporten el seu estat, i el del circuit, cap a un node que els gestiona, a través d’un bus de comunicacions. Això ens permet estalviar materials d’instal·lació i reduir encara més els costos del projecte. El resultat del sistema dissenyat canvia el sentit de la paraula centraleta, al convertir-se en un conjunt de mòduls que treballen de forma individual (descentralitzada). Aquesta soluciona els problemes detectats i ens permet fer una instal·lació més fàcil i econòmica, proporcionant una solució molt competitiva a l’hora d’introduir-la al mercat.

WOS: 000358934100018, Offering safe, relatively inexpensive and reproducible teaching environment for exploring phenomena, interactive course modules are applications of special interest in education. Engineering and physics students usually have difficulty understating the topic of electrical circuits. There is limited evidence in the literature supporting the premise that utilizing interactive course modules improves student learning for the topic of electric circuits. Understanding the topic of electric circuits is important for high school students who plan to enter engineering programs at universities in Turkey since it is a topic covered at the university entrance exam conducted nationwide. Moreover the topic of electric circuits is taught in many engineering programs. This study explored the question that whether the achievement of students using interactive course module is different from the achievement of students taught with didactic teaching along with traditional teaching tools with fifty high school students. The pre-test/post-test with control group research design is used to investigate the research question. Findings revealed that utilizing interactive course modules to teach the topic of electric circuits is found to improve students learning better than teaching the same content with didactic teaching along with traditional teaching tools. Further research should be undertaken to compare the use of the simulations and real laboratory equipment.