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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
51

Desenvolvimento de metodologia de simulação para conformidade em compatibilidade eletromagnética para projetos eletrônicos

Comin, Rodrigo 29 September 2017 (has links)
Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2018-04-25T13:02:31Z No. of bitstreams: 1 Rodrigo Comin_.pdf: 9770505 bytes, checksum: 7fab41aa9f91c2809d6d8bc966015c61 (MD5) / Made available in DSpace on 2018-04-25T13:02:32Z (GMT). No. of bitstreams: 1 Rodrigo Comin_.pdf: 9770505 bytes, checksum: 7fab41aa9f91c2809d6d8bc966015c61 (MD5) Previous issue date: 2017-09-29 / Nenhuma / O setor automotivo nacional, no segmento de fabricação de carrocerias para ônibus, vem buscando melhorar a qualidade de produção de seus veículos, visando atender as exigências do mercado interno e externo, por meio de especificações de projetos eletrônicos seguindo normas internacionais. Neste contexto, as normas de compatibilidade eletromagnética destacam-se, pois, possuem um papel importante para garantir que os equipamentos possam operar de forma segura, sem gerar ou sofrer interferências. Este trabalho tem como objetivo desenvolver uma metodologia para projetar produtos eletrônicos que necessitam atender normas de compatibilidade eletromagnética, por meio de estudos de técnicas de emissões radiadas e conduzidas, e uso de ferramentas computacionais para simulação da placa de circuito impresso. A partir deste estudo, pode-se diminuir investimentos com laboratórios de testes, tempo de desenvolvimento e disponibilizar produtos ao mercado de forma mais eficiente. O uso de técnicas apropriadas e boas práticas em projetos são meios adequados para atender requisitos de normas, porém a evolução das tecnologias e adição de mais circuitos em áreas menores torna necessário avançar nos conhecimentos. Assim, deve-se compreender de forma detalhada as técnicas para emissões de modo comum e diferencial, desenvolver simulações que possam prever resultados em testes de laboratórios e propor alterações em projeto mecânico ou eletrônico que atendam os limites determinados em normas. / The national automotive division, more precisely in the bus manufacturing segment, efforts are being deposited to improve the manufacturing quality of its vehicles in order to meet the requirements of the internal and external market through electronic projects based on international standards. Furthermore, the electromagnetic compatibility standards stand out because they have a major importance ensuring that electronic devices are able to provide safety to its users, without interfering or being interfered by other devices. The objective of this research is to develop a methodology to design electronic devices which must meet the standards requirements of electromagnetic compatibility. This goal is achieved through the study of radiated and conducted emissions techniques, and using computational tools for simulation of printed circuit boards. From this study it will be possible to reduce costs with laboratory tests, reduce the time required for development, and provide products to the customers in an efficient way. The use of appropriated techniques and good practices during the designs process are the proper way to meet standards and requirements. However, with the evolution of technology and addition of more electronic circuits in smaller areas requires to acquire more knowledge and go deeper in this study. Thus, it is necessary to understand in details the common mode and differential emissions technics, develop simulations which can provide a preview of what the laboratory tests may result, and propose changes in the mechanic and electronic project design in order to meet the limits of the requirements determined in the standards.
52

Etude CEM des réseaux embarqués / EMC study in embedded systems

Ales, Achour 07 June 2015 (has links)
Aujourd'hui CEM normative sur RSIL ne permet pas de garantir le bon fonctionnement de façon systématique. La sûreté est assurée au moyen de marges CEM, souvent excessives. Le système est donc sous optimal Par ailleurs, le fonctionnement des convertisseurs sur RSIL n'est pas forcément représentatif du fonctionnement réel: le RSIL n'est pas forcément représentatif des impédances des réseaux embarqués. De ce fait, le filtrage d'un convertisseur peut être optimisé sur RSIL mais n'est plus forcément optimal dès qu'on est sur un réseau réel. L'objectif de cette thèse est de progresser dans la modélisation CEM des réseaux embarqués, en vue de pouvoir prédire le comportement, et d'optimiser les moyens de filtrage. / Today normative LISN EMC does not guarantee the proper functioning systematically. Safety is ensured by EMC margins often excessive. The system is therefore suboptimal Furthermore, the operation of the converters on the AN is not necessarily representative of the actual operation : the AN is not necessarily representative of the impedances of embedded networks . Thus , filtering of a converter can be optimized but on the AN is not necessarily optimal since it is a real network . The objective of this thesis is to advance the EMC modeling of embedded systems in order to predict behavior, and optimize the filter means.
53

Optimisation du routage d'un filtre CEM / EMC filter layout optimization

Oliveira, Thomas de 18 July 2012 (has links)
La tendance de l'intégration en électronique de puissance accentue naturellement les effets électromagnétiques parasites. Tout système d'énergie électrique devient alors source de perturbations EM aussi bien conduites que rayonnées. Mais dans le cadre de ces travaux, nous nous sommes focalisé sur l'organe de filtrage des perturbations conduites : le filtre CEM. En haute fréquence, il s'avère que ce type de système voit son comportement dégradé en raison des différents phénomènes parasites apparaissant au sein même du dispositif. Seuls les aspects magnétiques du problème ont néanmoins été traités (i.e. inductances partielles & couplages magnétiques parasites). Différentes méthodes ont été mises au point par le passé dans le but d'améliorer facilement la réponse du filtre. Cependant, il s'agit de procédés empiriques ne pouvant garantir l'optimalité de la solution de filtre construite. Les travaux réalisés au cours de cette thèse ont donc consisté à développer une nouvelle méthode d'optimisation d'un filtre CEM, et plus précisément de son routage. L'objectif est alors d'exploiter les différents phénomènes magnétiques parasites intrinsèques au montage. Calculer ce type d'éléments a donc nécessité l'utilisation d'un outil de modélisation PEEC ; méthode numérique permettant des calculs rapides en raison d'un maillage relativement limité. / The actual trend to integrate the power electronic devices naturally increases the stray electromagnetic phenomena. Every electrical system becomes thus an EM disturbances source. But as part of this work, we especially focused on the filtering device of conducted disturbances : the EMC filter. For high frequencies, degradations can be observed over the filter transfer function due to the different stray electromagnetic phenomena occurring within the device. But only the magnetic aspects have nevertheless been treated (i.e. partial inductances & stray magnetic couplings). Different methods have been worked out in the past in order to easily improve the filter response. However, these are empirical processes that could not guaranty the built filter solution optimality. The works done throughout this PhD have consisted in developing a novel EMC filter optimization method, and more precisely of its routing. The aim has been to use the different stray magnetic phenomena. All of these elements can only be obtained by using a PEEC modeling tool. The PEEC method allows having fast numerical calculations thanks to a quite light meshing.
54

Trychtýřová hřebenová anténa pro měření EMC / Double-ridge waveguide horn antenna for EMC measurements

Martincová, Kateřina January 2018 (has links)
The thesis deals with the design and realization of a horn antenna for electromagnetic compatibility measurement. First it focuses on general theory of antennas, than it focuses more on horn antennas and their design. Second part deals with description of antenna realization and comparison of simulated results.
55

Elektromagnetická interference kardiostimulátorů / Electromagnetic interference and pacemakers

Kulík, Jindřich January 2008 (has links)
This thesis deals with electromagnetic compatibility of implantable electro-medical devices using in cardiology. The main aim of this thesis is detection of the resistance of implantable pacemakers (PM) and implantable cardioverter defibrillators (ICD) to the electromagnetic interference. In the first part of this thesis, a function of the heart, which is necessary for understanding of PM and ICD operation, is described. The function and construction of PM and ICD is detailed in the theoretical part as well. The next part is focused on the electromagnetic compatibility. The next part is description of the measurement method and the experimental arrangement used for practical experiments with electromagnetic resistance of PM and ICD.
56

Dopplersensor för rörelsedetektering / Motion Detection with Doppler Sensor

Lindberg, Anton, Strid, Mikael January 2015 (has links)
Inom miljöer med krav på hög säkerhet såsom kärnkraftverk behövs ett billigt och pålitligt alternativ för att snabbt och enkelt kunna detektera obehöriga individer vid intrång. Föreliggande rapport beskriver arbetet kring utveckling av en rörelsedetektor som har funktionen att detektera obehöriga personer inom områden där de inte har tillträde. Det slutliga målet med detta arbete är att konstruera en programmerbar krets som arbetar med signalerna från rörelsesensorn HB100, som utan underhåll kan täcka stora ytor. Arbetet har avgränsas till elektronikdesign, filterkonstruktion, EMC samt programmering av den färdiga kretsen. / Within environments with high demands on security like nuclear power plants there is a high demand on a cheap and reliable system for detection of unauthorized individuals of intrusion. This report describes the work on the development of a motion detection system using the doppler effect. The ultimate goal of this work is to design a programmable circuit that works with signals from the motion sensor HB100, which without maintenance can cover large areas. The work has been limited to electronic design, filter design, EMC and programming of the complete circuit.
57

Om att bedöma formler för att formulera bedömningar : En kvantitativ studie om precisionen i revisorers fortlevnadsbedömningar och konkursprediktionsmodeller

Detterfelt, Sebastian, Björkman, Isak January 2021 (has links)
Revisorer i Sverige har i tidigare studier funnits restriktiva med att ge ut fortlevnadsvarningar till konkursbolag. Det saknas studier om huruvida konkursprediktionsmodeller gör bättre förutsägelser  än revisorer i Sverige med hänsyn till kostnader för missklassificeringar (EMC). Syftet med studien är att jämföra precisionen i revisorers fortlevnadsbedömningar med precisionen i konkursprediktionsmodeller baserade på finansiella nyckeltal, samt att undersöka relationen mellan fortlevnadsvarningar, finansiella nyckeltal och konkurser. Studien är kvantitativ och har en deduktiv ansats med en komparativ forskningsdesign. Sekundärdata från svenska onoterade aktiebolags  årsredovisningar har använts.  Resultaten visar att revisorer i Sverige alltjämt är restriktiva med att ge ut fortlevnadsvarningar, men att deras bedömningar i huvudsak har högre precision än konkursprediktionsmodeller för K2-redovisande bolag. När redovisningen blir mer sofistikerad (K3), kan dock konkursprediktionsmodeller ge en högre precision. Studien belyser fortlevnadsbedömningar och konkursprediktionsmodellers utfall utifrån ett kostnadsperspektiv, samt bidrar med kunskap kring fördelar och begränsningar med konkursprediktionsmodeller inom revision. / Auditors in Sweden has been found restrictive with issuing going concern opinions to subsequent bankrupt companies. There is a lack of studies examining if bankruptcy prediction models make better predictions than auditors in Sweden when estimated misclassification costs (EMC) are considered. The purpose with this study is to compare the precision in going concern opinions with the precision from accounting-based bankruptcy prediction models, and to examine the relation between going concern opinions, accounting measures and bankruptcies. The study is quantitative with a deductive approach and comparative design. Secondary data from Swedish private limited companies’ annual reports has been used.  Our results show that auditors in Sweden are still restrictive with issuing going concern opinions, but that their evaluations to a large degree are more precise than the bankruptcy prediction models when used on companies that are reporting by the K2 framework. However, when the accounting numbers are more sophisticated by using the K3 framework, bankruptcy prediction models may be more precise. The study highlights going concern opinions and the outcome from bankruptcy prediction models through a perspective of estimated misclassification costs (EMC). It also contributes with knowledge regarding advantages and disadvantages with using bankruptcy prediction models in auditing.
58

Electromagnetic compatibility in wireline communications

Lauder, David Maxwell January 2007 (has links)
This document is a thesis submitted in partial fulfilment of the requirements of the University of Hertfordshire for the degree of Doctor of Philosophy (Part Time) in 'EMC in Wire-line Communications' in the School of Electronic, Communication and Electrical Engineering at the University of Hertfordshire. It describes a programme of research into the modelling and measurement of radio frequency interference emissions from various communication networks including Power Line (Tele)communications (PLC/PLT) and Digital Subscriber Line (DSL). An introduction and literature review are followed by the results of practical measurements on installed networks. These measurements include antenna gain and Longitudinal Conversion Loss (LCL). Power line communication networks, splitterless DSL and home phoneline networks in buildings are studied and modelled and the models are compared with the measured results. Improved EMC test methods are also described, in particular the modelling and design of four types of portable antennas for use in radiated EMC measurements with improved sensitivity at frequencies up to 30 MHz. The first type is a set of three manually tuned loop antennas covering 100 kHz - 30 MHz. The second is a set of three loop antennas that cover a similar frequency range but with remote tuning via an optical fibre link, under the control of software which also controls an EMC measuring receiver. The third type is a larger (1.6 m diameter) tuned loop covering 1.75 - 10 MHz that allows the measuring system noise floor to be below the typical atmospheric noise floor. The fourth type is an electrically short dipole covering 10 - 30 MHz with improved matching. The protection requirements for various types of radio communication services are analysed and are compared with emission levels from various types of wireline communication network. A review of existing applicable EMC standards and standards under development is also presented.
59

Electromagnetic Compatibility Requirements for Medical Device Certification / Elektromagnetisk Kompatibilitet Krav för Medicinsk Utrustning Certifiering

Imani, Shabnam, Farzaneh, Elnaz January 2017 (has links)
Until approximately 50 years ago, wireless electronics was confined to military purposes. With the advancement of technology, consumer electronics found widespread applications in almost every aspect of our lives and numerous devices were developed using electromagnetic waves to transfer different types of data. In light of such advancements, the electromagnetic compatibility (EMC) evolved from a military concept to regulate the radio frequency requirements of the battlefield equipment to a mature and essential part in manufacturing and employing electronic devices. Medical devices were no exception and largely benefited from the ease of connectivity and mobility provided by usage of wireless electronics. Due to the sensitive nature of medical devices and extreme consequences of their malfunction, EMC grew to a centric issue in design and production of such devices. This work examines the electromagnetic compatibility of a wearable biomedical measurement system used for the assessment of mental stress of combatants in real time. This system was developed as a part of the ARTEC project and supported by the Spanish Ministry of Defense through the Future Combatant program [1]. We focus on the EMC of the electrocardiogram of the system and aim to identify its EMC requirements of this system while assessing it against various standards and protocols. Throughout this study, we elucidate the fundamentals of electromagnetic compatibility with specific attention to medical devices. Furthermore, we present our results after conducting several EMC tests to measure the compatibility of the electrocardiogram device using the Intertek guidelines. The emission test was performed while essential counter measures such as appropriate shielding and anti-interference filters had been applied.
60

ASSESSMENT OF WATERSHED NUTRIENT LOADS AND EFFECTIVENESS OF BEST MANAGEMENT PRACTICES

Nazari, Saeid 01 January 2018 (has links)
Several methods have been developed for use in estimating the water quality loads associated with urban and agricultural landuses and practices. These include the use of sophisticated computer models, typically based on using pollutant loading and runoff functions, regression equations, load export coefficients (LECs), and event mean concentrations (EMCs). This research has examined the feasibility of using a simple EMC approach with the Kentucky Nutrient Model (KYNM). The thesis includes an extensive literature review of EMCs and a synthesis of recommended values for a range of typical urban and agricultural landuses. The thesis also includes an extensive literature review of potential BMPs along with a summary of the typical removal efficiencies and costs associated with each type of BMP. The research also explored the potential to use the results from multiple applications of site specific BMP models like the Source Loading and Management Model (WinSLAMM) in the development of general functional relationships that could then be used to evaluate BMP performance on a more site-specific basis. The developed EMC table and the associated BMP performance curves should provide valuable tools for use in better managing nutrient loads for urban and agricultural watersheds.

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