共查询到19条相似文献,搜索用时 109 毫秒
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倾斜井眼中感应测井正演模拟与响应特征 总被引:4,自引:0,他引:4
感应测井仪器的发射源可简化为一系列磁偶极子,其在层状地层中产生的电磁场可分解成彼此独立的TE波和TM波叠加,且TE波和TM波完全由两个标量方程确定.首先研究倾斜井眼中磁偶极子场的TE波和TM波分解,推导多层介质中电磁场振幅以及地层界面上广义反射和透射系数的递推公式,给出层状地层电磁场解析解.然后利用数值结果分析考察砂泥岩薄交互层中,地层层厚、井眼倾角变化等对感应测井响应的影响. 相似文献
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采用递推矩阵方法计算径向成层介质中的二维Green函数.根据层界面处电场和磁场的连续性条件得到确定待定系数的矩阵方程组并通过递推方法快速求解.只需改变方程组中源项元素的位置,就可以方便地得到当源点和场点在任意层时的二维Green函数,并进而得到具有任意半径的圆形电流在介质中产生的电磁场.本文给出的Green函数具有表达方式简洁的优点. 相似文献
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采用在圆柱坐标系中分离变量的方法,推出填充多层互易手征介质的金属同轴线各层电磁场之间的关系,得到其模式特征方程和圆波导模式特征方程,给出了填充两层手征介质金属同轴线部分模式的色散特性的数值计算结果,分析了手征介质参量及两层手征介质厚度变化等对手征同轴线传播特性的影响。如果互易手征介质的手征参数等于零,可得填充普通介质的同轴线的模式特征方程。与填充普通介质的同轴线中的模式相比,手征同轴线中的模式发生了分叉。当同轴线中所填介质的折射率增大时,其模式归一化截止频率和进行基模单模传输的带宽归一化频率都将减小。 相似文献
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推导了 NMR实验中任意条件下柱状介质所感受到的有效磁场和固有化学位移的公式 ,概括了通过单谱仪、双谱仪和魔角实验校正化学位移的方法 ,阐述了平行场和垂直场中的介质磁化率效应。 相似文献
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用边有限元方法计算磁偶极子的三维电磁响应 总被引:5,自引:0,他引:5
用边有限元基函数导出了麦克斯韦(Maxwell)方程的有限元关系式,计算了地下三维介质中磁偶极子的电磁场响应.将场分量定义在有限单元的边上,解决了结点有限元方法中场切向分量不连续的矛盾,保证了源除外的所有单元内有旋无散的特性.将总场分离成背景场和二次场,使该方法适用于任何方向的磁偶极子源.通过模拟算例分析了7种Krylov子空间迭代算法以及不完全乔累斯基分解预处理手段在解大型线性代数方程组中的计算效率和收敛特性.对比结果表明,施加不完全乔累斯基分解作预处理的广义乘积型双共轭梯度算法GPBiCG (Pbicg)收敛最快,是三维复杂介质电磁响应数值模拟的首选算法. 相似文献
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新型金属-多层绝缘介质-金属表面等离子波导结构的传输特性 总被引:1,自引:0,他引:1
设计了一种新型金属-多层绝缘介质-金属表面等离子波导结构,利用时域有限差分法对其传输特性进行数值分析。研究了有效折射率和传播长度与中间多层绝缘介质厚度之间的关系,并分析了金属层的角度对该波导结构中场分布的影响。结果表明:当光波从波导结构上方垂直入射时,电磁场被限制在多层介质中的高折射率区,实现了场的耦合传输。多层绝缘介质的厚度均为220 nm时,正六边形金属层结构对应的波导结构的传输性能较为理想。该结构能够实现亚波长尺度的光限制,可以应用于光电子集成和传感器领域。 相似文献
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The influence of the conduction-electron spin magnetization density, induced in a two-dimensional electron layer by a microwave electromagnetic field, on the reflection and transmission of the field is considered. Because of the induced magnetization and electric current, both the electric and magnetic components of the field should have jumps on the layer. A way to match the waves on two sides of the layer, valid when the quasi-two-dimensional electron gas is in the one-mode state, is proposed. By following this way, the amplitudes of transmitted and reflected waves as well as the absorption coefficient are evaluated. 相似文献
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We report a new kind of laser-threshold resonance in electromagnetic wave propagation inside a layered medium. Specifically, for large values of the gain coefficient, the wave interaction with only the first few lattice interfaces results in transmission and reflection values of much greater than unity. We also show that the duality phenomenon between losses and gains on the field amplitude decay is due to the existence of counterpropagating waves on reflection from the layer interfaces. 相似文献
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We compute the reflected and refracted electromagnetic fields for an ideal semi-infinite body (either a plasma or a dielectric), as well as the reflection coefficient, by using a general approach based on the polarization equation of motion and electromagnetic potentials. The method consists of representing the charge disturbances by a displacement field in the positions of the moving charges. The propagation of an electromagnetic wave in matter is treated by means of the retarded electromagnetic potentials, and the resulting integral equations are solved. Generalized Fresnel’s relations are thereby obtained for any incidence angle and polarization and the angles of total polarization and total reflection are derived (the latter for the plasma). Bulk and surface plasmon–polariton modes are also identified for the plasma. As it is well known, the field inside the plasma is either damped (evanescent) or propagating (transparency regime), and the reflection coefficient exhibits an abrupt enhancement on passing from the propagating regime to the damped one (total reflection). 相似文献
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We compute the reflected and refracted electromagnetic fields for an ideal semi-infinite (half-space) plasma, as well as the reflection coefficient, by using a general procedure based on equations of motion and electromagnetic potentials. The approach consists of representing the charge disturbances by a displacement field in the positions of the moving particles (electrons). The propagation of an electromagnetic wave in plasma is treated by means of the retarded electromagnetic potentials, and the resulting integral equations are solved. Generalized Fresnel’s relations are thereby obtained for any incidence angle and polarization and the angles of total polarization and total reflection are derived. Bulk and surface plasmon-polariton modes are identified. As it is well known, the field inside the plasma is either damped (evanescent) or propagating (transparency regime), and the reflection coefficient exhibits an abrupt enhancement on passing from the propagating regime to the damped one (total reflection). 相似文献
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为了分析纳米金表面修饰对表面等离子体共振(SPR)的放大作用,以及其对传感器本身的影响,首先,基于色散介质的吸收理论,通过建立波长型SPR生物传感器四层膜结构的数学模型,理论分析了传感器表面所吸附纳米金对传感器的影响:纳米金的表面修饰,改变了表面等离子体传感器中棱镜表面各介质层内电磁场的能量分布,削弱了金属膜在共振吸收中的作用,从而使SPR曲线的半波宽度增加,最小反射系数增大,金膜的最优膜厚度也随之改变.其次,通过不同厚度的金膜外吸附纳米金的对比试验,验证了此理论.金膜厚45nm、表面修饰10nm纳米金颗
关键词:
表面等离子体共振
生物传感器
纳米金
金属膜 相似文献
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《Waves in Random and Complex Media》2013,23(3):373-380
Abstract We report a new kind of laser-threshold resonance in electromagnetic wave propagation inside a layered medium. Specifically, for large values of the gain coefficient, the wave interaction with only the first few lattice interfaces results in transmission and reflection values of much greater than unity. We also show that the duality phenomenon between losses and gains on the field amplitude decay is due to the existence of counterpropagating waves on reflection from the layer interfaces. 相似文献
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In this study, we investigate Faraday rotation of electromagnetic waves that are anomalously transmitted through an over‐dense magnetized plasma layer. Here, magnetized plasma indicates that the plasma layer is immersed in a uniform magnetic field. Firstly, normally opaque over‐dense magnetized plasma is shown to be transparent to obliquely incident electromagnetic waves. This high transparency can be achieved by providing conditions for resonant excitations of plasmonic modes. The resonant characteristics of the transmission coefficient of the considered structure are determined and discussed. The conditions under which the magnetized plasma behaves as a complete reflector are also obtained. Faraday rotation is shown to be enhanced under high transparency conditions. The reflected wave also exhibits Faraday rotation and is enhanced under total reflection conditions. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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Diego González-Herrero Jose María Muñoz Carlos Torres Pablo Hernández-Gómez Óscar Alejos Carlos de Francisco 《Applied Physics A: Materials Science & Processing》2013,112(3):719-725
A new method for measuring the electromagnetic properties (permittivity and permeability) of nanopowder materials in a wide microwave region is presented. Unlike previously developed systems, our experimental setup is based on reflection measurements over a short-circuited transmission line combined with the application of a uniform magnetostatic field. When this field is sufficiently high to saturate the material, the effective permeability of the sample equals the permeability of free space, without modifying its electrical properties. Hence, for each frequency, the permittivity can be obtained through the measurement of a single scattering parameter, such as the reflection coefficient. After this first measurement, and once the external field is removed, the reflection coefficient can be used again to obtain the permeability by means of the permittivity value obtained before. As the major advantage, this procedure allows the recording of the experimental data in just one sweep, using one-port measurements, and without modifying the geometrical characteristics of the sample holder. Hence, the measurement process can be easily automated. 相似文献
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Kalluri Dikshitulu Shrivastava R. K. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1974,2(4):206-210
The oscillations in the power reflection coefficient as a function of the normalized slab velocity are shown for electromagnetic waves obliquely incident on a relativistically moving uniaxial plasma slab with an infinitely strong magneto-static field parallel to the slab boundaries. This paper also summarizes and concludes the sequence on the reflection and transmission of electromagnetic waves obliquely incident on relativistically moving uniaxial and isotropic plasma slabs. 相似文献