Many mathematical models generally consist of either a continuous system like that of a system of differential equations, or a discrete system such as a discrete game theoretic model; however, there exist phenomena in which neither modeling approach alone is sufficient for capturing the behaviour of the intended real world system. This leads to the need to explore the use of combinations of such discrete and continuous processes, namely the use of mathematical modeling with what are known as hybrid dynamical systems. In what follows, we provide a blueprint for one approach to study several classes of equilibrium problems in non-equilibrium states through the direct use of hybrid dynamical systems. The motivation of our work stems from the fact that the real world is rarely, if ever, in a state of perfect equilibrium and that the behaviour of equilibrium problems in non-equilibrium states is just as complex and interesting (if not more so) than standard equilibrium solutions. Our approach consists of an association of classes of traffic equilibrium problems, noncooperative games, minimization problems, and complementarity problems to a class of hybrid dynamical system called projected dynamical systems. The purposed connection between equilibrium problems and projected dynamical system is made possible through mutual connections to the robust framework of variational inequalities. The results of our work include theoretical contributions such as showing how evolution solutions (non-equilibrium solutions) can be analyzed from a theoretical point of view and how they relate to equilibrium solutions; computational methods for tracking and visualizing evolution solutions and the development of numerical algorithms for simulation; and applications such as the effect of population vaccination decisions in the spread of infectious disease, dynamic traffic networks, dynamic vaccination games, and nonsmooth electrical circuits.

Οι ηλεκτρικά μικρές κεραίες χαρακτηρίζονται από εμπεδήσεις με μεγάλες αντιδράσεις και μικρή αντίσταση ακτινοβολίας. Αυτές οι αντιδράσεις λειτουργούν ως αποθήκη της ενέργειας που δίνεται στην κεραία μην επιτρέποντας της να ακτινοβολεί. Η προσαρμογή αυτών των εμπεδήσεων σε μια συγκεκριμένη τιμή αντίστασης (πχ 50 Ω) είναι πραγματική πρόκληση. Σε αυτή την εργασία θα εξετάσουμε τη δυνατότητα χρησιμοποίησης ενεργών κυκλωμάτων αρνητικής αντίστασης ώστε να «ακυρώσουμε» σε μια μεγάλη περιοχή συχνοτήτων τη χωρητική- επαγωγική συμπεριφορά μιας κεραίας, καθιστώντας έτσι το έργο της προσαρμογής πιο εύκολο. Στο πρώτο κεφάλαιο εξετάζουμε εισαγωγικές έννοιες των κεραιών και της προσαρμογής. Στο δεύτερο ασχολούμαστε θεωρητικά με κυκλώματα που παράγουν στην είσοδο τους μια αρνητική εμπέδηση. Στο τρίτο και στο τέταρτο κεφάλαιο εφαρμόζουμε την παραπάνω λογική σε ένα μονόπολο και μια patch κεραία αντίστοιχα. / Electrically small antennas present impedances characterized by large reactance and small radiation resistance. These reactances act to store much of the energy input to the antenna instead of allowing it to radiate. Matching these impedances to a 50-Ohm source is a real challenge. In this project we will consider the use of active negative resistance circuits in order to cancel out over o broadband the capacitive-inductive behavior of an antenna, making the task of matching easier. In the first chapter we consider introductory concepts of antennas and matching. In the second chapter we theoretically deal with circuits that produce a negative impedance at their input. In the third and fourth chapter we apply the previous concepts to a monopole and a patch antenna respectively.

Aulas experimentais são indispensáveis para o adequado aprendizado de conteúdos de Física. Nos últimos anos, surgiram diversos softwares de simulação de experimentos de Física. A partir da utilização de softwares, busca-se verificar se o aluno consegue visualizar em atividades virtuais as situações que são reais. A proposta é trabalhar com atividades que possibilitem mostrar que é possível aprender circuitos elétricos utilizando softwares de simulação. Todas as atividades desenvolvidas são parte do produto didático e estão organizadas em um CD-ROM. Como referencial teórico, adota-se a Teoria dos Campos Conceituais, de Gerard Vergnaud. Para esse autor, o sujeito se apropria do conhecimento, que pode ser pensado e organizado em campos conceituais, ao longo de muito tempo, por meio de experiência, maturidade e aprendizagem. O projeto foi aplicado a alunos da disciplina de Física e Eletricidade, no Curso de Sistemas de Internet, do Instituto Federal Sul-rio-grandense, campus Pelotas, RS. Foram escolhidos os softwares Modellus e PhET (Physics Education Technology), os dois considerados softwares gratuitos. Em um primeiro momento, foram trabalhados circuitos elétricos a partir desses softwares. Na sequência, as atividades foram repetidas em um painel construído especialmente para esse fim com o objetivo de analisar o desempenho dos alunos em circuitos reais. A partir dos dados colhidos durante o trabalho, foi possível obter evidências de que houve uma aprendizagem significativa sugerindo que, de fato, as situações (VERGNAUD, 1990) é que dão sentido aos conceitos. / Experimental classes are essential for the proper learning of physics content. In recent years emerged various software simulation experiments in physics. From the use of software try to verify if the student can view activities in virtual situations that are real. The proposal is to work with activities that enable show that it is possible to learn electric circuits using simulation software. All activities are part of the educational product and are organized on a CD-ROM. The theoretical approach we have adopted the Conceptual Fields Theory Gerard Vergnaud. For this author, the subject appropriates the knowledge, which can be thought of as organized in semantic fields over a long time, through experience, maturity and learning. The design was applied to students of Physics and Electronics, Travel in Internet Systems South of Rio Grande Federal Institute campus Pelotas, Brazil. Modellus the software and PhET (Physics Education Technology) were chosen, both considered free software. At first electrical circuits from these softwares were worked. Following the activities were repeated in a panel specially built for this purpose in order to analyze the performance of students in real circuits. From the data collected during the study it was possible to obtain evidence that there was a significant learning suggesting that, in fact, situations (VERGNAUD, 1990) is to give meaning to the concepts.

Orientador: José Antenor Pomilio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação / Made available in DSpace on 2018-08-16T03:53:14Z (GMT). No. of bitstreams: 1 Bonaldo_JaksonPaulo_M.pdf: 2972818 bytes, checksum: d23d65d56a50edebdb72fdfa13beb6b6 (MD5) Previous issue date: 2010 / Resumo: Esta dissertação aborda conversores eletrônicos de potência utilizados em processos de produção de ozônio por descarga eletrostática em alta freqüência, propondo técnicas para melhorar o desempenho do sistema, bem como aumentar a confiabilidade do mesmo. Uma das técnicas propostas é utilizada para evitar a saturação dos transformadores de alta tensão, por meio da introdução de um controle rápido de corrente. Um controle lento da tensão também é introduzido, visando eliminar níveis médios que possam existir nas tensões, evitando assim a atuação prolongada do controle de corrente. Com intuito de aumentar a potência do sistema e, conseqüentemente, a geração de ozônio, são realizados estudos baseados em uma topologia de conversores polifásicos. É proposta uma nova técnica de controle para equalizar as potências nas fases do conversor. Discrepâncias nas potências ocorrem devido às diferenças entre os valores dos parâmetros das células geradoras de ozônio e dos transformadores, levando a um desbalanceamento da carga polifásica conectada ao conversor. A técnica de equalização consiste basicamente em aplicar tensões desbalanceadas à carga para compensar o desequilíbrio. Para tanto, é necessário realizar a realimentação de tensões e correntes no primário dos transformadores. São apresentados estudos, simulações e resultados experimentais para validar as técnicas e topologia propostas. Os resultados obtidos a partir da implementação prática convergem para os resultados obtidos por simulação, indicando que os métodos estudados são viáveis para a aplicação / Abstract: This work discusses power electronic converters used in ozone generation by highfrequency electrostatic discharge, suggesting techniques to improve the system performance and increase its reliability. One of the techniques is used to avoid saturation of the high voltage transformer through the introduction of a fast current control. A slow voltage control is introduced too. This control eliminates average levels that may exist under the voltage, thus avoiding the actuation of the current control for long time. A poly-phase topology is studied in order to increase the power delivered to the load and, consequently, the generation of ozone. A new control technique is proposed to equalize the power among the phases of the converter. Discrepancies in power values, among converter phases, are due to the dispersion of the parameters of the ozone generating cells and transformers, leading to a load imbalance. The equalization technique consists basically on applying unbalanced voltages to the load, in order to compensate the load unbalance. Therefore, it is necessary to perform the feedback voltage and currents on the primary side of transformers. It is presented studies, as well as, simulations and experimental results to validate the topology and the proposed techniques. The results obtained from the implementation converge to the simulated ones, indicating that the studied methods are feasible for implementation / Mestrado / Energia Eletrica / Mestre em Engenharia Elétrica

Made available in DSpace on 2016-08-17T14:53:13Z (GMT). No. of bitstreams: 1 Jacob de Melo Cruz.pdf: 515166 bytes, checksum: 2bda304fdbb90f8e9e02395f91554a0a (MD5) Previous issue date: 2010-08-19 / The active and reactive power services and transmission losses allocation methods had became an important issue after implantation of power systems new economic model and with open market access to agents (generators and loads) due the increase global power demand. The objective is to solve the problem of power services and transmission losses allocations and finding services beneficiaries as well transmission losses responsibilities to each market agents of a fair and equitable way. The results of the allocation problem are very important to economics evaluations of investments in futures generations and loads units installations. Several allocation methods has been proposed in the specialized technical literature, however due the non-linear characteristic of transmission losses and loads, there isn t an ideal method, and still remains the equity question. This work is intented to propose a method to simultaneously allocations performing active and reactive power service and transmission active and reactive losses. The method is based on circuit laws and superposition principle. The method suggest a modeling of sources and loads as equivalent admitances and taking into account the similarities, based on electric circuits, of power services and transmission losses allocations. The proposed method uses a load flow results and divide network into operation scenarios and generators and loads are modeling as equivalent admittances and the current injections are null and then the network is represented by branches and active and reactive power generated or consumed are determined and allocating among market agents. Finally, analysis, simulations and comparisons with some methods proposed in literature are performed, using four buses test system and IEEE 30 buses. / Os métodos de alocação de serviços de potência ativa e reativa e das perdas de transmissão ativa e reativa têm recebido cada vez mais atenção após a reestruturação do setor elétrico, que promoveu livre acesso a diversos agentes (geradores e cargas), e com a crescente demanda de energia pela economia global. O principal objetivo dos métodos de alocação é determinar a participação dos agentes de uma forma justa e equilibrada nos serviços de potência e nas perdas de transmissão. A alocação é muito importante na avaliação econômica de investimentos para as localizações de novas instalações de unidades de geração e consumo. Diversos métodos para resolução do problema de alocação têm sido propostos na literatura técnica especializada, contudo, devido à natureza não-linear das perdas, não existe um método aceito como ideal. Neste trabalho, é proposto um método de alocação simultânea dos serviços de potência ativa e reativa e das perdas de transmissão ativa e reativa, baseada nas leis de circuitos e no princípio da superposição. A motivação desta proposta está no fato que, do ponto de vista de circuitos elétricos, esses processos de alocação têm tratamento similar. A diferença surge posteriormente, no momento da interpretação dos resultados obtidos. O método se baseia no resultado do fluxo de carga e divide o problema em cenários de operação, modelando os geradores e cargas como admitâncias equivalentes um de cada vez. Em seguida, a rede é representada por ramos e as potências ativa e reativa geradas ou consumidas são determinadas e alocadas aos agentes. Finalmente, são realizadas simulações, análises e comparações com alguns métodos propostos usando um sistema teste de 4 barras e o sistema IEEE 30 barras.

Aulas experimentais são indispensáveis para o adequado aprendizado de conteúdos de Física. Nos últimos anos, surgiram diversos softwares de simulação de experimentos de Física. A partir da utilização de softwares, busca-se verificar se o aluno consegue visualizar em atividades virtuais as situações que são reais. A proposta é trabalhar com atividades que possibilitem mostrar que é possível aprender circuitos elétricos utilizando softwares de simulação. Todas as atividades desenvolvidas são parte do produto didático e estão organizadas em um CD-ROM. Como referencial teórico, adota-se a Teoria dos Campos Conceituais, de Gerard Vergnaud. Para esse autor, o sujeito se apropria do conhecimento, que pode ser pensado e organizado em campos conceituais, ao longo de muito tempo, por meio de experiência, maturidade e aprendizagem. O projeto foi aplicado a alunos da disciplina de Física e Eletricidade, no Curso de Sistemas de Internet, do Instituto Federal Sul-rio-grandense, campus Pelotas, RS. Foram escolhidos os softwares Modellus e PhET (Physics Education Technology), os dois considerados softwares gratuitos. Em um primeiro momento, foram trabalhados circuitos elétricos a partir desses softwares. Na sequência, as atividades foram repetidas em um painel construído especialmente para esse fim com o objetivo de analisar o desempenho dos alunos em circuitos reais. A partir dos dados colhidos durante o trabalho, foi possível obter evidências de que houve uma aprendizagem significativa sugerindo que, de fato, as situações (VERGNAUD, 1990) é que dão sentido aos conceitos. / Experimental classes are essential for the proper learning of physics content. In recent years emerged various software simulation experiments in physics. From the use of software try to verify if the student can view activities in virtual situations that are real. The proposal is to work with activities that enable show that it is possible to learn electric circuits using simulation software. All activities are part of the educational product and are organized on a CD-ROM. The theoretical approach we have adopted the Conceptual Fields Theory Gerard Vergnaud. For this author, the subject appropriates the knowledge, which can be thought of as organized in semantic fields over a long time, through experience, maturity and learning. The design was applied to students of Physics and Electronics, Travel in Internet Systems South of Rio Grande Federal Institute campus Pelotas, Brazil. Modellus the software and PhET (Physics Education Technology) were chosen, both considered free software. At first electrical circuits from these softwares were worked. Following the activities were repeated in a panel specially built for this purpose in order to analyze the performance of students in real circuits. From the data collected during the study it was possible to obtain evidence that there was a significant learning suggesting that, in fact, situations (VERGNAUD, 1990) is to give meaning to the concepts.

No description available.

The project idea was created from the demand of a renewal for a Power Distributor Unit also known as a PDU. The current product had successively turned in to a cable mess because of short term solutions. This made the product non user friendly, inconvenient and non-agile to handle troubleshooting. To develop this project, a PCB design was created by simplifying and improving circuit diagrams until satisfied. Once the final circuit diagram was obtained, a PCB layout design was created. The result of the project, due to limited time, was only theoretical. The finished product was not tested as there was no time allowing this.

The purpose of this physics didactics work is to contribute to an increased knowledge of learning about electrical circuits. This is done partly through a literature studyof students’ difficulties, but also through an examination of test items on electrical circuits used in the Swedish upper secondary school. In addition to the study, a side project in the form of a translation from English to Swedish of a diagnostic test of understanding of electrical circuits, DIRECT, was carried out. Analyzing the test items on electrical circuits, 18 different categories were developed based on the collected material. The most common type of item was an item about power which also had a connection to reality. Each category was discussed in relation to the theoretical background and some items of additional interest were analyzed in more detail. Several conclusions were made based on this project, for example that a significant part of the items do not require understanding for the question but can be solved by mechanical use of formulas. In line with the research presented a considerable part of the items are dedicated to current on a conceptual level. Another conclusion was that items dealing with shorts and changes in a circuit would have been a welcome addition to the test items. / Syftet med detta fysikdidaktiska arbete är att bidra till en ökad kunskap om lärande om elektriska kretsar. Detta görs dels genom en litteraturstudie av elevers svårigheter, men också genom en undersökning av provuppgifter om elektriska kretsar som används i den svenska gymnasieskolan.Utöver undersökningen genomfördes ett sidoprojekt i form av översättning från engelska till svenska av ett diagnostiskt test av förståelse för elektriska kretsar, DIRECT. I undersökningen utarbetades 18 olika kategorier för uppgifterna om elektriska kretsar utifrån det insamlade materialet. Den vanligaste uppgiftstypen var en uppgift som handlar om effekt och som dessutom hade en verklighetskoppling. Varje uppgiftskategori diskuterades i relation till den teoretiska bakgrunden och några uppgifter av större intresse analyserades mer ingående. Flera slutsatser kunde dras av projektet, till exempel att en stor del av uppgifterna inte kräver större förståelse för frågan utan kan lösas med mekanisk användning av formler. I linje med den fysikdidaktiska forskningen ägnas dock en ansenlig del av uppgifterna åt ström på en konceptuell nivå. En annan slutsats var att uppgifter som behandlar kortslutning och förändringar i en krets hade varit ett välkommet tillägg bland provuppgifterna.

<p>        The last decade has witnessed an explosive growth in highly data-centric applications such as Internet of Things (IoT) and Artificial Intelligence (AI). Such applications demand highly efficient data storage and processing, especially when the systems operate under high energy/resource constraints, such as in intermittent-powered systems or edge AI platforms. Therefore, at the hardware level, high storage capacity along with low power operations has become more crucial than ever. Although conventional silicon-based complementary metal-oxide semiconductor (CMOS) has brought great prosperity to the semiconductor industry to date, enabling high-performance computing, increasing leakage energy and low cell density hinder their ability to sustain their benefits at scaled nodes and meet the demands of emerging data-intensive workloads. On the other hand, emerging non-volatile memories (NVMs) have gained much attention due to their distinct advantages over CMOS, such as zero leakage, high density, and non-volatility. However, they suffer from issues associated with high write power, endurance and/or variability. Thus, there is a need for new memory technologies that offer high density, low power and high-performance attributes to meet the data storage and efficiency demands of the new workloads. Furthermore, such technological advances need to be supported by architectural innovations. Despite hardware advances, the energy efficiency gains in traditional von-Neumann architectures are limited by power-hungry data movements between memory and processor, also known as the memory bottleneck. To alleviate this issue, in-memory computing (IMC) has emerged as a promising technique, wherein certain computations are executed within a memory macro, thus reducing processor-memory transactions. Along similar lines, incorporating non-volatile storage in logic state elements, such as flip-flops, has gained much attention for intermittently-powered systems, wherein the state of the processor is efficiently backed-up in the local non-volatile memory in the event of a power failure. Such techniques enabling logic-memory synergy reduce compute, storage, and/or communication costs and thus can be highly promising for future computing platforms. However, existing techniques for logic-memory fusion suffer from key design bottlenecks that need to be mitigated via extensive technology-circuit-architecture co-design. In this dissertation, we address some of the issues associated with data storage and processing by exploring spin-based low-power non-volatile devices, their memory applications, and logic-memory coupling enabled by their unique technological attributes. </p> <p>      We propose spin-based devices that employ the valley-spin Hall (VSH) effect in monolayer transition metal dichalcogenides (TMDs), such as tungsten di-selenide (WSe2). With the unique features of WSe2, the proposed devices are designed to have an integrated back-gate, enabling control of the charge and spin currents in 2D TMD channel. This design leads to an access-transistor-less compact layout in memory arrays. The generated spin currents diverge into opposite directions with out-of-plane spins, allowing for the coupling of WSe2 with perpendicular magnetic anisotropy (PMA) magnets. This enables low-power write operations and facilitates differential logic encoding within a single device. Additionally, we utilize inter-layer exchange-coupling mediated by FeCo-oxide and Ta layers to electrically isolate but magnetically couple the PMA free layers. This configuration benefits read performance by achieving low series resistance in the read path. To ensure reliable inter-layer coupling and the functionality of the proposed devices, we perform micromagnetic OOMMF simulations and extensively investigate the impact of process variations on the exchange-coupled PMA free layers. From the simulations, we conclude that the proposed design is resilient to potential process variations arising from misalignment of the PMA free layers and reductions in exchange-coupling strength. Based on the proposed devices, we explore circuit designs for logic and memory applications. </p> <p>      First, we propose VSH effect-based non-volatile flip-flops (VSH-NVFFs) using the proposed devices to introduce non-volatility in logic targeted for intermittently powered systems. The key challenge to design such systems is to enable energy-efficient data back-up in the event of power failure. In our design, we achieve high energy-efficiency via device-circuit co-design of VSH devices and NVFFs. We propose two flavors of NVFFs: NVFF-1 with a compact design and NVFF-2 targeted for lowering data restore energy. Compared to existing giant spin Hall (GSH) effect-based NVFFs, also known as spin-orbit torque or SOT-NVFFs, our NVFFs exhibit 68%-71%, 74%-75% and 55%-59% lower normal, back-up, and restore energies, respectively. Among the proposed VSH-NVFFs, NVFF-1 exhibits 8% lower operation energy than NVFF-2, while NVFF-2 exhibits 6% lower back-up energy and 11% lower restore energy. This result suggests that NVFF-1 is more suitable for systems with a smaller number of checkpointing operations (data back-up/restore), while NVFF-2 is beneficial for systems needing a larger number of checkpointing operations. Furthermore, by conducting Monte Carlo simulations, we confirm the reliable restore operation of the proposed NVFFs.</p> <p>      Secondly, we design memory arrays using the proposed devices to gain benefits over previously proposed VSH effect-based memory designs, in which read currents flow through a highly resistive 2D TMD channel, degrading read performance. For read operations, our memory array requires a read access transistor. By sharing the read access transistor per word, we minimize the area overhead in our memory array design. The area of our bit-cell is comparable to a previously proposed VSH memory, despite the inclusion of an additional read access transistor. Additionally, with the electrical isolation of the read and write paths in our design, we achieve improvements in read performance, with reductions of 39%-42% and 36%-46% in read time and energy, respectively. However, this improvement comes at the cost of write performance, with a 1.7X and 2.0X increase in write time and energy, respectively. We also achieve a 1.1X-1.3X larger sense margin (SM) and a 1.2X-1.3X improvement in read disturb margin (RDM). Furthermore, by increasing the size of the read access transistor in our memory array, we can further improve the SM by up to 1.5X-1.6X with only a 7%-12% area increase. Our design can be particularly useful for applications that involve frequent reads and few writes, such as neural accelerators.</p> <p>      We further expand our exploration of VSH effect-based devices for implementing IMC. As XNOR-based binary neural networks (BNNs) have shown immense promise for resource-intensive AI edge systems, their implementation has been explored using SRAMs and emerging NVMs. However, these designs typically need two bit-cells (2T-2R) to encode signed weights, resulting in an area overhead. Therefore, we address this issue by proposing a compact and low-power IMC technique for XNOR-based dot products. Our approach utilizes the VSH effect in monolayer WSe2 to design XNOR bit-cells that feature an access-transistor-less compact layout and differential weight encoding in a single device (XNOR-VSH). We co-optimize the proposed VSH device and the memory arrays to enable efficient in-memory dot product computations between signed binary inputs and signed binary weights. The compactness of the proposed XNOR-VSH array leads to 4.8%-9.0% lower compute latency and 36.6%-62.5% lower compute energy, along with 49.3%-64.4% smaller area compared to spin-transfer torque magnetic RAM (STT-MRAM) and SOT-MRAM based XNOR-arrays.</p> <p>      Lastly, we explore the modeling and design of voltage-controlled spintronic devices, which have shown remarkable potential for ultra-low-power and high-speed operation empowered by magnetoelectric (ME) materials. The proposed ME device utilizes a monolayer WSe2 channel placed on top of a Cr2O3 ME dielectric, which are electrostatically controlled by top and bottom gates. To capture the electrostatics in 2D TMD and the gate-voltage-dependent ME effect, we establish a modeling framework using a distributed capacitive network. This framework self-consistently accounts for the interactions between the various components. We verify the functionality of the proposed model by simulating the proposed device, and show how it can capture the device characteristics.</p>