Academic literature on the topic 'Magnetic sheet'

The work in this thesis focuses primarily on equilibrium and stability properties of collisionless current sheet models, in particular of the force-free Harris sheet model. A detailed investigation is carried out into the properties of the distribution function found by Harrison and Neukirch (Physical Review Letters 102, 135003, 2009) for the force-free Harris sheet, which is so far the only known nonlinear force-free Vlasov-Maxwell equilibrium. Exact conditions on the parameters of the distribution function are found, which show when it can be single or multi-peaked in two of the velocity space directions. This is important because it may have implications for the stability of the equilibrium. One major aim of this thesis is to find new force-free equilibrium distribution functions. By using a new method which is different from that of Harrison and Neukirch, it is possible to find a complete family of distribution functions for the force-free Harris sheet, which includes the Harrison and Neukirch distribution function (Physical Review Letters 102, 135003, 2009). Each member of this family has a different dependence on the particle energy, although the dependence on the canonical momenta remains the same. Three detailed analytical examples are presented. Other possibilities for finding further collisionless force-free equilibrium distribution functions have been explored, but were unsuccessful. The first linear stability analysis of the Harrison and Neukirch equilibrium distribution function is then carried out, concentrating on macroscopic instabilities, and considering two-dimensional perturbations only. The analysis is based on the technique of integration over unperturbed orbits. Similarly to the Harris sheet case (Nuovo Cimento, 23:115, 1962), this is only possible by using approximations to the exact orbits, which are unknown. Furthermore, the approximations for the Harris sheet case cannot be used for the force-free Harris sheet, and so new techniques have to be developed in order to make analytical progress. Full analytical expressions for the perturbed current density are derived but, for the sake of simplicity, only the long wavelength limit is investigated. The dependence of the stability on various equilibrium parameters is investigated.

Deformation and annealing texture in the cold rolled low carbon steels is important for sheet metal forming operations and service performance. The aim of this study is to non-destructively investigate the effect of texture on magnetic anisotropy. Various samples having different textures and residual stress states, due to different % reduction in thickness, annealing and stress relieving treatment, were prepared. Texture maps were obtained by Magnetic Barkhausen noise measurements performed with 100 steps between the ranges of 00-3600 on the surface. Microstructure investigation by optical &amp<br>scanning electron microscopy<br>hardness and tension tests were performed<br>and texture was determined by X-Ray diffraction method. The results were compared, evaluated and discussed to establish relationship between texture and magnetic Barkhausen Noise emission.

Ressonância Magnética (RM) é uma técnica bastante versátil, pois é utilizada em muitas áreas de pesquisa, como biologia, física, química, engenharia e medicina. Apesar disso, constitui-se uma desvantagem o alto custo do equipamento e suas restrições físicas para alguns experimentos. Para reduzir essas desvantagens, o grupo de pesquisadores do CIERMag está desenvolvendo um equipamento de RMN multipropósito e, para complementá-lo, este trabalho vem desenvolver um subsistema non-real-time que gerencia os dispositivos periféricos de um experimento. Foi proposta uma rede de dispositivos que é controlada por um Raspberry Pi como elemento central, o qual está conectado ao terminal computadorizado do sistema através de uma rede local (Local Area Network - LAN) via Ethernet e conectado aos dispositivos periféricos via Serial Peripheral Interface (SPI). Com o objetivo de ser possível gerenciar qualquer tipo de dispositivo, foi desenvolvido um conjunto de parâmetros baseado no Transducer Electronic Data Sheet (TEDS), definido no padrão IEEE 1451, de modo que cada dispositivo, normalmente um transdutor, possui seu próprio. Foram elaboradas duas interfaces de software: uma desenvolvida em Python e a outra uma interface web HTML. Ambas as interfaces possuem as mesmas funcionalidades: editor e gerenciador de TEDS, visualização gráfica de medidas dos sensores e interface para os atuadores.<br>Magnetic Resonance (MR) is a very versatile technique, since it is used in many research areas such as biology, physics, chemistry, engineering and medicine. Despite this, the cost of the equipment and its physical restrictions in some experiments constitute a serious drawback. To minimize these problems, the CIERMag research team is developing multipurpose MR equipment and, to complement this equipment, this work develops a non-real-time subsystem that manages the peripheral devices of the experiment. It was proposed a network of devices controlled by a Raspberry Pi as its central element, which is connected to the terminal computer of the system. The protocol adopted for this was Ethernet via Local Area Network (LAN); communication with peripheral transducers was performed with the Serial Peripheral Interface (SPI). With the objective to be able to manage any type of device, we created parameter sets based on Transducer Electronic Data Sheet (TEDS), defined in the IEEE 1451 standard, so each device, normally a transducer, has its own parameter set. We created two software interfaces: one developed with Python and the other is a HTML web interface. Both have the same functionalities: a TEDS editor and manager, a graphical visualization of sensor measurements and also an actuator interface.

Thesis (Ph. D.)--Ohio State University, 2005.<br>Title from first page of PDF file. Document formatted into pages; contains xxi, 261 p.; also includes graphics (some col.). Includes bibliographical references (p. 244-254). Available online via OhioLINK's ETD Center

Actuellement, la principale voie d'amélioration des performances des aciers magnétiques utilisées dans les machines tournantes est l'obtention d'une texture préférentielle type "cubique" {100}<001> ou planaire {100}<0vw>. De plus, pour l'ensemble des tôles magnétiques, le laminage à chaud est une étape incontournable du procédé. Or il a été montré antérieurement que des microstructures de laminé à chaud non recristallisées et fortement déformées hétérogènement coïncidaient avec l'émergence d'une texture finale prononcée et une sensible amélioration des performances magnétiques. Nous avons examiné en laboratoire les possibilités d'obtention de textures {100} par laminage à chaud pour des alliages Fe Si et Fe Si Al d'au moins 0, 1 mm d'épaisseur. L'étude de l'importance des différents recuits et laminage à froid du procédé nous ont permis de préciser la part de divers phénomènes (taux de réduction globale, hétérogénéité du laminage à chaud, teneur en aluminium, microstructure initiale) dans l'accroissement des performances. Enfin, la croissance anormale de germes favorablement orientés a été envisagée pour les alliages Fe Si par l'intermédiaire d'inhibiteur AIN et est une voie de progrès pour le futur. Pour des applications à plus hautes fréquences (supérieure à 50 Hz) l'épaisseur des tôles doit être inférieure à 100 microns pour limiter les courants induits. Partant de travaux anciens, des tôles minces en texture "cubique" ont été obtenues par simple ou double laminage à froid de tôles G. O. Commerciale associés à une croissance anormale contrôlée par différence d'énergie de surface. Nous montrons en particulier l'importance de l'état de recristallisation primaire comme point de départ de la croissance anormale et son influence sur la qualité de la texture finale obtenue sur les performances magnétiques

本論文では，鉄損算出精度向上を目的としたプレイモデルによるヒステリシス特性を考慮した磁界解析の実用化に向けて，ヒステリシスモデルのモデリング精度向上，計算機の記憶容量低減，有限要素磁界解析の計算時間削減に関する手法を提案した．さらに，ヒステリシス特性の考慮の有無が解析結果に与える影響を検討し，提案したヒステリシス特性を考慮した有限要素磁界解析の実用性を明らかにした．<br>In order to achieve the highly accurate analysis of an iron loss for electric machines, this paper proposes finite element magnetic field analyses taking account of the hysteretic property by using the play model. As a consequence, it is verified that the proposed method can accurately estimate an iron loss of a magnetic materials and decrease computational costs. Furthermore, this paper investigates the influence of the hysteretic property in finite element magnetic field analyses to demonstrate its effectiveness.<br>博士(工学)<br>Doctor of Philosophy in Engineering<br>同志社大学<br>Doshisha University

Le but de notre étude est de prendre en compte le comportement bidimensionnel non linéaire et anisotrope des tôles magnétiques, utilisées en génie électrique, afin de pouvoir effectuer une modélisation par éléments finis aussi réaliste que possible. Nous avons développé un modèle original de loi de comportement de tôles magnétiques (à grains orientés, à grains non orientés, à texture cubique) fondé sur l'équivalence entre la relation vectorielle B(H) et une représentation magnétique 11. Les données expérimentales nécessaires sont les courbes B(H) suivant la direction de laminage (axe x) et striant la direction travers qui lui est orthogonale (axe y). Le comportement magnétique des tôles est pris en compte par une représentation adéquate des lignes isovaleurs de coénergie dans le plan HxHy. La relation B(H) est ensuite restituée à partir de la densité de coénergie. Une vérification expérimentale du modèle a été effectuée grâce à un cadre en champs tournants. Nous avons implanté le modèle dans un logiciel éléments finis avec une formulation en potentiel scalaire. Des exemples d'application ont été traités (alternateur et transformateur)