共查询到20条相似文献,搜索用时 109 毫秒
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S. Koroglu N. Umurkan O. Kilic F. Attar 《Simulation Modelling Practice and Theory》2009,17(7):1267-1275
The electromagnetic interference has many undesired effects to the office equipments and the performance of technological devices. Therefore, electrical devices should have field protection mechanism against magnetic fields. The shielding mechanism prevents external magnetic field emitted from the device to the vicinity area. This work attempts to apply artificial neural network in order to estimate shielded magnetic field for multilayer shielding application. The multilayer magnetic shielding performances of cylindrical shaped ferromagnetic shields under extremely low frequency are investigated. For this purpose, three different ferromagnetic materials in cylindrical shape are chosen for magnetic shielding. The shielding performances of these materials are measured and a selected set of data is used to train and test an artificial neural network. The proposed neural network model achieves an intelligent decision for the shielded magnetic field level based on distance, unshielded magnetic field value, number of shield layer and skin-depth of the shield. 相似文献
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利用遗传算法(GA)编写多涂层优化设计程序,该程序可以调用矢量网络分析仪测量的电磁参数,根据吸波材料的电磁参数对0.5~6.0GHz范围内不同材料的涂层厚度进行优化设计;讨论了不同的目标函数和厚度优化方法对优化结果的影响,提出多常数权重法建立目标函数。结果表明:此方法可以简单地从材料电磁参数的数据库中,按照设定的要求计算得到最优的电磁波吸收涂层;利用提出的多常数权重法建立的目标函数可以更好的设计宽频带高吸收的电磁波吸收涂层。 相似文献
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随着半导体技术的不断发展,集成电路的电路速度、集成密度和I/O端口数量已大大增加,FPGA的小型化、高密度集成会引发电磁兼容性的问题,电磁屏蔽是抑制电磁辐射最有效的方法,选择高效的电磁屏蔽材料可以取得良好的屏蔽效果。而目前电磁屏蔽材料在FPGA上的应用较少,因此选取了一款具有代表性的高性能FPGA作为研究对象,通过近场扫描测试来研究不同状态下FPGA的电磁辐射发射问题;针对芯片的特点,选取了复合金属屏蔽罩和吸波导电海绵作为电磁屏蔽材料,对FPGA的辐射发射进行抑制。进一步的实验结果表明,由金属材料复合而成的屏蔽罩具有更好的屏蔽效能,达到了10 dBm,相比之下,吸波导电海绵的压缩性和结构稳定性更有助于FPGA在多场景下应用。 相似文献
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随着信息化的高速发展,电子设备数量与日俱增,使用的密集程度越来越大,电磁干扰也越来越突出。为确保这些设备在工作时不会受到外界电磁场的干扰,同时不对该环境中其他设备造成不允许的电磁干扰,必须对电子设备进行电磁屏蔽。阐述了电子设备屏蔽设计要求、屏蔽效能的影响因素、电子设备应采取的屏蔽措施,并通过屏蔽设计改进实例说明电磁屏蔽技术在电子设备结构设计中的重要作用。 相似文献
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在研究PS/2键盘控制模块的时钟与数据信号接口电路结构特征的基础上,利用电路等效的方法研究了键盘电磁泄漏发射与信息还原机理,通过测试实验验证了该方法的有效性;进一步提出了两种电磁泄漏防护方式,具体设计了一种电磁泄漏防护方案。实验测试结果表明,该方案能够有效抑制键盘的电磁发射,防止按键信息通过电磁发射被还原。 相似文献
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根据磁耦合谐振式无线电能传输原理,建立两线圈的磁耦合谐振式电路模型,通过金属材料相对磁导率的引入,分析了不同金属环境对无线电能传输系统的自感、互感、传输效率的影响.采用Maxwell磁场计算软件计算无金属环境及不同金属环境下收发线圈参数,再利用Maxwell和Simplorer联合仿真分析电磁屏蔽效果;利用联合仿真探究了金属环境对系统传输特性的扰动并实验验证.铁磁性屏蔽板铁、镍的存在有效约束了空间磁场分布,具有很好的电磁屏蔽作用,减少电磁干扰;同时使得无线电能传输系统的收发线圈电感增大,而金属铜、铝环境中对无线电能传输系统几乎无影响,与无金属环境结果相同.最后通过实验验证实验结果与理论分析的一致性. 相似文献
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《Computer Standards & Interfaces》2010,32(3):101-109
A new class of auxetic materials, a hexachiral honeycomb structure with good mechanical properties, is investigated through computer simulation and measurement. The electromagnetic properties for shielding applications are taken into account. This new material shows some interesting EMC properties (e.g. − 40 dB transmittance at 2.4 GHz) and promises better performance using different insertion techniques. 相似文献
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S. A. Kolesnik 《Mathematical Models and Computer Simulations》2014,6(5):480-489
A method is proposed for the numerical solution of coefficient inverse problems on nonlinear heat transfer in anisotropic materials used for heat shielding in the aerodynamic heating of hypersonic craft (HC). The main characteristics of anisotropic heat-shielding materials at high temperatures are the components of a nonlinear thermal conductivity tensor that are to be restored based on the results of the experimental measurements of the temperature in space-time nodes. The proposed method is based on the alternating direction method with extrapolation of the numerical solution of heat transfer problems, the method of parametric identification, and the gradient descent method. The results have been obtained for the reconstruction of components of a thermal conductivity tensor for carbon-carbon composite material using the experimental values of the nonlinear heat conduction of these materials. The method can be employed for restoring other numerous thermophysical characteristics of composite materials. The obtained results of the numerical experiments on the identification of components of a thermal conductivity tensor of composite materials in a two-dimensional space are presented and discussed. 相似文献
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碳纤维复合材料在很多领域得到广泛应用,尤其是航空航天领域。为了研究雷电对于碳纤维材料的间接效应,以民用客机为应用背景,使用CST2017软件,选择TLM(传输线矩阵)时域求解器,对带有缝隙的立方体模型进行了仿真计算。得到了雷电流分量A波和H波作用下,航空铝合金材料和碳纤维复合材料模型的表面电流分布、内部电磁场分布以及内部三类电缆的电磁耦合规律。结果表明,碳纤维材料较之金属材料的屏蔽效能较小,线缆感应电流大小受雷电流参数影响显著,扭绞和屏蔽能有效减少电磁干扰。这些结果可以为飞机雷电间接效应防护提供参考。 相似文献
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以材料电磁性能变化为依据,对材料及构件实施缺陷探测和性能测试的一类检测方法统称为电磁无损检测法,其基本原理是电磁场理论。对传统的涡流检测以及近年来发展起来的交流电磁场检测和电磁层析成像检测等三种方法的原理、系统结构、应用范围等进行了详细介绍,并分析了它们各自的特点,为综合应用和发展这几种电磁无损检测方法提供了一定的参考。 相似文献
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对采用单层不锈钢外壳的矿用产品的电磁屏蔽效能进行了分析与计算,得出产品金属外壳的电磁屏蔽效能与采用的金属材质、厚度以及因加工工艺形成的隙缝、开孔有关,为提高矿用产品的电磁屏蔽性能提供了工程经验。 相似文献
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从车辆耐撞结构和吸能材料两方面入手,基于材料与结构一体化思想,利用数值仿真技术研究某高速动车被动安全性问题.设计5种适用于高速动车的吸能结构,分别为普通双层吸能管结构,3种端部带有不同薄弱环节的双层吸能管结构和泡沫铝材料夹心双层吸能管结构;利用PAMCRASH软件,分别将5种不同吸能结构安装到整车上进行相同编组对撞试验仿真;针对碰撞仿真结果评价车辆的整体被动安全性,并通过各工况结果的对比分析找出最优吸能装置.结果表明:泡沫铝夹心吸能装置在加速度和逃生空间评价指标中表现最好,在以后的吸能结构设计中可适当采用. 相似文献
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Lei Li Guodong Zhang Kapil Khandelwal 《Structural and Multidisciplinary Optimization》2018,58(4):1589-1618
For energy absorbing structures made up of ductile materials, the plastic strain accumulation often leads to early material damage and failure, which can deteriorate the overall structural performance. The goal of this work is to limit this damage in elastoplastic designs using the density-based topology optimization framework such that the optimized structures can absorb energy in a more controllable manner. To this end, an implicit nonlocal coupled elastoplastic damage model is considered for simulating the material damage and softening behavior. The nonlocal effect from the void elements is removed by introducing a scaling scheme for the nonlocal parameters. Path-dependent sensitivity is derived analytically using an adjoint method whose accuracy is further verified by the central difference method. The effectiveness of the proposed method is demonstrated through several numerical examples. It is shown that the load-carrying capacity, ductility, as well as ultimate plastic work dissipation capacity of the optimized design, can be considerably improved by the proposed method. 相似文献
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FDTD方法吸收边界条件的研究及应用 总被引:1,自引:1,他引:0
用时域有限差分法(FDTD)求解电磁散射问题中,吸收边界条件的设置起着关键性作用.通过时间和空间上的递推算法对时域有限差分法中的两种吸收边界条件:Mur吸收边界条件和完全匹配层(PML)的吸收效果进行了比较和分析.同时,引入参数对PML的差分方程进行了优化,避免了将电磁场分裂为两个分量进行计算,进而降低了计算内存开销.实验结果证明PML具有更优越的吸收性能.最后,在FDTD算法中应用PML吸收层对一圆柱形导体的雷达散射截面积(RCS)进行数值仿真,验证了FDTD算法在计算雷达散射截面积(RCS)上的有效性. 相似文献
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To predict electromagnetic field distribution inside a loaded enclosure with the aperture, we present a hybrid formulation which combines method of moments and finite element method. To predict efficiency of the method, the shielding effectiveness of an empty enclosure is compared with the literature. Then the method is applied to dielectric slab loaded enclosure with the single aperture, and the shielding effectiveness, ratio of stored electrical energy, and dissipated power variations are obtained. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. 相似文献