关于各向异性基本电子元件欧姆定律的两种形式

由于各向异性电阻元件的导电各向异性，使电流密度方向和电场强度方向不一致，从而欧姆定律表现为两种形式：电流密度方向的欧姆定律和电场强度方向的欧姆定律。相应地存在一个二阶电阻张量和一个二阶电导张量。并给出了它们的计算公式。分析表明各向异性电阻元件的欧姆定律具有近似性。     

双轴各向异性介质特征参数的测试模型

介质参数测试的关键理论步骤是求解相应的电磁逆问题。本文利用等效传输线法导出了已知双轴各向异性电磁材料复介电常数张量ε^-和复磁导率张量μ^-，计算出反射系数和透射系数（正问题）的理论公式后，提出了一种新的求解逆问题的理论方法。由介质对正入射TE、TM波的反射系数与透射系数，可用公式直接反演得到ε^-和μ^-的复分量εx、μy和εy,μx然后利用介质对斜入射TE、TM波的透射系数由大为简化的反演算法迭代求解它们的z分量εz和μz。计算机模拟实验给出了比较理想的结果。     

基于各向异性扩散偏微分方程的图像去模糊

利用图像结构张量导出的各向异性扩散滤波,具有平滑噪声的同时保持细节的特点,提出基于结构张量的能量最小化去卷积正则化模型,并对由此导出的偏微分方程应用于灰度图像和向量值图像去模糊作了分析。灰度图像的各向异性扩散滤波可以由梯度平滑的结构张量实现,相应的偏微分方程取决于平滑结构张量决定的惩罚函数。与其它非线性扩散滤波去模糊的方法比较结果证实所提方法在信噪比和视觉质量上都具有更好的效果。     

光热辐射方法测量各向异性材料的热导张量

报道了一种用光热辐射（PTR）技术测量各向异性材料热导张量的简单方法。本文从各向异性介质的热传导理论出发，推导出该材料的幅频和相频关系；在实验上用PTR方法测出幅频和相频曲线，拟合出热导率，并得到各向异性材料的热导张量。     

弥散加权成像在原发性癫痫诊断中的诊断价值

目的:应用弥散加权成像(DTI)分析原发性癫痫(IE)大脑白质弥散张量的改变.方法:对30名原发性癫痫患者以及30名正常对照者,分别行常规T1WI、T2WI、FLAIR序列以及DTI检查,并重建每个受试者的平均弥散系数(ADC)图及部分各向异性(FA)图,分别在双侧海马、额叶、丘脑以及胼胝体膝部、压部测量ADC与FA值...     

基于GPU加速的各向异性双边滤波图像抽象化绘制算法

本文提出基于GPU加速的图像及视频的实时抽象化绘制算法。首先通过运用Kuwahara滤波实现图像的颜色特征快速聚类,其次采用各向异性双边滤波算法对图像沿结构张量场进行平滑,从而获得连续的、局部区域色彩一致的结果图像,实验表明该算法简单、易于实现。     

摩擦材料的各向异性对超声马达特性的影响

制备了3种不同纤维排列方向的摩擦材料，在超声马达模拟试验装置上，研究了摩擦材料的各向异性对超声马达性能的影响，探讨了摩擦材料纤维取向的作用。试验结果表明，纤维平行于滑动方向排列且有较高的弹性模量的各向异性摩擦材料，对改善超声马达的性能是有益的。     

(101)单轴应力对Si材料电子电导率有效质量的影响

由Schrdinger方程出发,基于(101)单轴应力下Si材料导带E-k解析模型,重点研究沿任意晶向(101)单轴应力对Si材料电子电导率有效质量的影响。结果表明:(101)单轴应力沿0°和45°晶向均导致导带底附近的六度简并能谷分裂成两组分立的能谷;(101)单轴张应力下,沿45°晶向的电子电导率有效质量随应力增大而明显减小,沿0°和90°晶向的电子电导率有效质量随应力增大而明显增大;(101)单轴压应力下,Si材料沿高对称晶向的电子电导率有效质量随应力增大而明显增大或几乎不变。     

大范围恒功率调速IPM-PMASR电机的最优设计

IPM—PMASR电机的设计实质上是磁体材料用量和转子结构各向异性之间的折中。各向异性设计的越好，需要的磁体材料就越少。磁体材料的增加总是有利于功率因数和电机转矩性能。不过，当需要大范围恒功率调速时，较少的磁体材料也能保征高速区的安全运行，只是逆变器发生故障时会出现短时过电压。因此，应该使转子各向异性达到最大。     

两同心各向异性等离子体球电磁散射的解析解

利用各向异性等离子体介质的电磁场满足各向异性等离子体球矢量波函数的条件，根据球Bessel函数的特点，分别给出两同心各向异性等离子体介质的球矢量波函数的解析表达式。在此基础上，应用电磁场在球边界上切向电场和磁场连续和远区辐射条件，导出在平面波入射情况下，两同心各向异性等离子体介质本征函数解的展开系数。理论分析和数值计算的结果表明：当两同心等离子体球媒质参数相同时，本文所得的结果可退化为单层各向异性等离子体解析解。同时数值计算还给出了本方法与矩量法-共扼梯度-傅立叶变换(MOM-CG-FFT)的比较结果，两者符合较好。     

The Role of Anisotropy Ratio in Backscattering of Spherically Anisotropic Particles: An Analytical Electromagnetic Characterization

We propose an analytical approach to characterize the role of anisotropic ratio in the light scattering of spherical layers with spherical anisotropy defined in spherical coordinates. Single-layer model, thin-film coating, and a collection of such spherical particles are all treated analytically, with the emphasis on the role of anisotropy in the scattering properties. Two types of anisotropic potentials are established to take into account the electric and magnetic anisotropy ratios (AR) which are fundamental to represent the electromagnetic fields in the presence of spherical polar crystallites. This paper provides a new method to depict the particle-illumination interaction at a macroscopic view, and gives new insight to the study of anisotropic interaction of particularly oriented molecular layers, elucidating the importance of anisotropy ratios in the scattering control.     

Highly In‐Plane Optical and Electrical Anisotropy of 2D Germanium Arsenide

Anisotropic 2D materials exhibit unique optical, electrical, and thermoelectric properties that open up possibilities for diverse angle‐dependent devices. However, the explored anisotropic 2D materials are very limited and the methods to identify the crystal orientations and to study the in‐plane anisotropy are in the initial stage. Here azimuth‐dependent reflectance difference microscopy (ADRDM), angle‐resolved Raman spectra, and electrical transport measurements are used to systematically characterize the influence of the anisotropic structure on in‐plane optical and electrical anisotropy of 2D GeAs, a novel group IV–V semiconductor. It is proved that ADRDM offers a way to quickly identify the crystal orientations and also to directly characterize the in‐plane optical anisotropy of layered GeAs. The anisotropic electrical transport behavior of few‐layer GeAs field‐effect transistors is further measured and the anisotropic ratio of the mobility is as high as 4.6, which is higher than the other 2D anisotropic materials such as black phosphorus. The dependence of the Raman intensity anisotropy on the sample thickness, excitation wavelength, and polarization configuration is investigated both experimentally and theoretically. These data will be useful for designing new high‐performance devices and the results suggest a general methodology for characterizing the in‐plane anisotropy of low‐symmetry 2D materials.     

Optical and electrical properties of two-dimensional anisotropic materials

Two-dimensional(2D) anisotropic materials, such as B-P, B-As, GeSe, GeAs, ReSe2, KP15 and their hybrid systems, exhibit unique crystal structures and extraordinary anisotropy. This review presents a comprehensive comparison of various 2D anisotropic crystals as well as relevant FETs and photodetectors, especially on their particular anisotropy in optical and electrical properties. First, the structure of typical 2D anisotropic crystal as well as the analysis of structural anisotropy is provided. Then, recent researches on anisotropic Raman spectra are reviewed. Particularly, a brief measurement principle of Raman spectra under three typical polarized measurement configurations is introduced. Finally, recent progress on the electrical and photoelectrical properties of FETs and polarization-sensitive photodetectors based on 2D anisotropic materials is summarized for the comparison between different 2D anisotropic materials. Beyond the high response speed, sensitivity and on/off ratio, these 2D anisotropic crystals exhibit highly conduction ratio and dichroic ratio which can be applied in terms of polarization sensors, polarization spectroscopy imaging, optical radar and remote sensing.     

Enhanced optical polarization anisotropy in quantum wells under anisotropic tensile strain

Anisotropic in-plane strain in quantum wells leads to an optical polarization anisotropy that can be exploited in optoelectronic devices such as modulators. A theoretical model shows that the behavior of the polarization anisotropy with increasing strain anisotropy is radically different for quantum wells under anisotropic tensile and compressive strains of equal magnitude. This strikingly different behavior arises from the different valence-subband mixing that occurs in the cases of anisotropic tensile and compressive strain. Specifically, the mixing of the first heavy- and light-hole subbands that occurs only under anisotropic tensile strain is central to the polarization anisotropy.     

Application of the radio-frequency interferometry method to a stratifield anisotropic medium

Interference patterns are calculated for a horizontal dipole laid on the surface of a stratified medium with both anisotropic permittivity and permeability tensors. The anisotropy in permitivity affectts the radiated fields in the endfire direction, and the anisotropy in permeability affects those in the broadside direction. The effects of anisotropy are illustrated for various cases.     

Simulation of Nano Si and Al Wires Growth on Si(100) Surface\+*

Because of the importance in microelectronics and their unique properties,the nanosilicon wires or other nano metal wires grown on Si(1 0 0 ) surface have been extensively in-vestigated and itis now a field ofvery active research[1—...     

各向异性PDLC散射膜的特性研究

采用摩擦表面取向层的方法制备了有光学各向异性结构的ＰＤＬＣ膜。研究了液晶盒的厚度、摩擦强度,以及在紫外光诱导相分离过程中的光照强度对ＰＤＬＣ膜的光学各向异性程度和电光特性的影响。对ＰＤＬＣ的光学各向异性进行了研究,并给出了要获得低阈值电压、高各向异性的聚合物分散液晶各向异性膜的盒厚、摩擦强度以及光照度等条件。被取向后的ＰＤＬＣ各向异性膜可被用来作为具有很好光电特性的电可调散射式偏振片。     

High-frequency EM scattering by edges in artificially hard and softsurfaces illuminated at oblique incidence

Uniform high-frequency expressions describing the field scattered by edges in anisotropic impedance surfaces illuminated at oblique incidence are provided. The specific anisotropic impedance boundary condition considered here exhibits a vanishing surface impedance along a principal anisotropy axis and an arbitrary one in the orthogonal direction. In certain circumstances, this tensor surface impedance may represent an accurate model for describing the scattering properties of artificially hard and soft surfaces. In order to simplify the analysis but without losing pertinence with real problems, in all canonical configurations we consider a face of the wedge to be perfectly conducting. The anisotropic impedance face is characterized by a tensor surface impedance with the principal anisotropy axes parallel and perpendicular to the edge     

Influence of anisotropic conductivity on EEG source reconstruction: investigations in a rabbit model

The aim of our work was to quantify the influence of white matter anisotropic conductivity information on electroencephalography (EEG) source reconstruction. We performed this quantification in a rabbit head using both simulations and source localization based on invasive measurements. In vivo anisotropic (tensorial) conductivity information was obtained from magnetic resonance diffusion tensor imaging and included into a high-resolution finite-element model. When neglecting anisotropy in the simulations, we found a shift in source location of up to 1.3 mm with a mean value of 0.3 mm. The averaged orientational deviation was 10 degree and the mean magnitude error of the dipole was 29%. Source localization of the first cortical components after median and tibial nerve stimulation resulted in anatomically verified dipole positions with no significant anisotropy effect. Our results indicate that the expected average source localization error due to anisotropic white matter conductivity is within the principal accuracy limits of current inverse procedures. However, larger localization errors might occur in certain cases. In contrast, dipole orientation and dipole strength are influenced significantly by the anisotropy. We conclude that the inclusion of tissue anisotropy information improves source estimation procedures.