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Bidirectional reflectance one-dimensional rough distribution function modeling of surface in the microwave band 下载免费PDF全文
In this study, the bidirectional reflectance distribution function (BRDF) of a one-dimensional conducting rough surface and a dielectric rough surface are calculated with different frequencies and roughness values in the microwave band by using the method of moments, and the relationship between the bistatic scattering coefficient and the BRDF of a rough surface is expressed. From the theory of the parameters of the rough surface BRDF, the parameters of the BRDF are obtained using a genetic algorithm. The BRDF of a rough surface is calculated using the obtained parameter values. Further, the fitting values and theoretical calculations of the BRDF are compared, and the optimization results are in agreement with the theoretical calculation results. Finally, a reference for BRDF modeling of a Gaussian rough surface in the microwave band is provided by the proposed method. 相似文献
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《Waves in Random and Complex Media》2013,23(3):332-343
Through in-depth analysis of the scattering properties of a one-dimensional random rough surface, a method to calculate the spatial bidirectional reflectance distribution function (BRDF) characteristics of a randomly rough surface is proposed. The scattering characteristics of an electrically large rough surface can be substituted by combination of subsection electromagnetic fields. The radar cross-section (RCS), which is transformed from the BRDF, is compared with numerical results from the Method of Moment (MoM). The agreement of the results verifies that this method could calculate the electromagnetic scattering field efficiently and straightforwardly. Moreover, the resulting combined fields from the BRDF of subsections in the rough surface show a good match with the entire scattering field of a whole surface, which indicates that a large electrically rough surface could be feasibly and effectively substituted with the combination of scattering elements using the BRDF method and the statistical method. 相似文献
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A relation for estimating the reflectance of a very rough surface with an approximately one-dimensional distribution of roughness is derived for the case of normal incidence and reflection in the specular direction within the solid diffraction angle. The reflectance values are determined both experimentally and by calculation using the derived relation for two approximately one-dimensional rough steel samples with rms roughnesses of 0.5 and 1.3 μm for a wavelength of 0.6328 μm. The resulting values are found to agree satisfactorily with each other. 相似文献
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《Waves in Random and Complex Media》2013,23(1):105-134
When solving scattering or emissivity problems for rough surfaces, the shadowing effect is often taken into account. Furthermore, for rough surfaces with large root mean square slope, surface reflections of the incidence or emission ray should not be neglected, especially at large observation angles. In this paper, a model of the monostatic statistical illumination function for one-dimensional rough surfaces with single surface reflection is developed, which is based on the Smith illumination function. A Monte Carlo ray-tracing algorithm is used to evaluate the accuracy of the present model. It is shown that, when neglecting the correlation between heights and slopes of the surface, the present model agrees quite well with the Monte Carlo result. Moreover, the result is improved if the correlation between heights and slopes is taken into account. For practical purposes, an empirical factor is introduced to improve the performance of the uncorrelated first-order illumination function to avoid computing the correlated one, which takes a long computation time. Besides, the first-order illumination function is significant at large observation angles, which could be promising to overcome problems in models of surface infrared emissivity where underestimation occurs compared with experimental measurements. 相似文献
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由于自然环境遭到人为因素的破坏,我国沙地面积正在逐步扩大,确定沙地的性质与面积已经成为改善环境的重要的指示性信息.遥感技术以其特有的优势可以为沙地监测提供科学有效的信息.本文以不同粒径沙地表面为研究对象,测量其双向反射信息,分析粒径大小对沙地表面反射特性的影响;基于现有的模型对不同粒径大小沙地表面的反射信息进行计算,与实测信息进行对比.研究结果表明,粒径大小对沙地表面反射的反射分布特性有明显的影响;通过对比测量的反射信息与模型计算的反射信息发现,利用双向反射模型可以准确地计算出不同粒径沙地表面的反射信息.本研究不仅确定了粒径大小对反射信息的影响,也为遥感技术估算沙地表面粒径大小以及研究地表固有光学特性提供参考. 相似文献
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V. T. Prokopenko S. A. Alekseev N. V. Matveev I. V. Popov 《Optics and Spectroscopy》2013,114(6):961-964
The dependences of the polarization parameters of probe radiation on the observation geometry and relations between the Stokes vector parameters have been simulated based on the bidirectional reflectance distribution function as applied to active polarimetric systems. 相似文献
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基于理论分析, 实验研究了二维磁单负材料/双正材料/磁单负材料表面等离子波导的滤波效应. 研究表明, 该波导结构具有低通滤波性质, 引入分支缺陷之后, 由于谐振效应该波导具有带阻滤波效应. 分支缺陷相当于亚波长谐振腔, 谐振腔的长度决定带阻滤波器的中心频率, 而中心频率几乎不受缺陷位置的影响; 滤波器透射率下降的幅度由耦合距离决定. 通过引入谐振腔及改变谐振腔的长度、数量以及耦合间距等参数, 可以实现可调节的表面等离子波导滤波器. 实验结果与理论分析符合得很好, 该性质将在可调的单通道或多通道带阻滤波器件中具有潜在的应用价值.
关键词:
表面等离子激元
特异材料波导
谐振腔
滤波器 相似文献
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Speckle correlations in the light scattered from a weakly rough one-dimensional random metal surface
Malyshkin V McGurn AR Leskova TA Maradudin AA Nieto-Vesperinas M 《Optics letters》1997,22(13):946-948
Perturbation theory is used to compute the angular-intensity correlation function C(q, k|q(?), k(?)) = ?[I(q|k) - ?I(q|k)?][I(q(?)|k(?)) - ?I(q(?)|k(?))]? for p-polarized light scattered from a weakly rough, one-dimensional random metal surface. I(q|k) is the squared modulus of the scattering matrix for the system, and q , q(?) and k , k(?) are the projections on the mean scattering surface of the wave vectors of the scattered and the incident light, respectively. Contributions to C include (a) short-range memory effect and time-reversed memory effect terms, C((1)) ; (b) an additional short-range term of comparable magnitude C((10)) ; (c) a long-range term C((2)) ; (d) an infinite-range term C((3)) ; and (e) a new term C((1.5)) that along with C((2)) displays peaks associated with the excitation of surface polaritons. These new features arise when the factorization approximation is not made in calculating the correlation function C . 相似文献
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In this paper, the atomic force microscopy (AFM)-based 2-D pushing of nano/microparticles investigated on rough substrate by assuming a multipoint contact model. First, a new contact model was extracted and presented based on the geometrical profiles of Rumpf, Rabinovich and George models and the contact mechanics theories of JKR and Schwartz, to model the adhesion forces and the deformations in the multipoint contact of rough surfaces. The geometry of a rough surface was defined by two main parameters of asperity height (size of roughness) and asperity wavelength (compactness of asperities distribution). Then, the dynamic behaviors of nano/microparticles with radiuses in range of 50–500 nm studied during their pushing on rough substrate with a hexagonal or square arrangement of asperities. Dynamic behavior of particles were simulated and compared by assuming multipoint and single-point contact schemes. The simulation results show that the assumption of multipoint contact has a considerable influence on determining the critical manipulation force. Additionally, the assumption of smooth surfaces or single-point contact leads to large error in the obtained results. According to the results of previous research, it anticipated that a particles with the radius less than about 550 nm start to slide on smooth substrate; but by using multipoint contact model, the predicted behavior changed, and particles with radii of smaller than 400 nm begin to slide on rough substrate for different height of asperities, at first. 相似文献
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S. I. Vinokurova M. T. Smirnov A. A. Chukhlantsev 《Radiophysics and Quantum Electronics》1991,34(4):394-397
Institute of Radio Engineering and Electronics, Academy of Sciences of the USSR. Translated from Izvestiya Vysshykh Uchebnykh Zavedenii, Radiofizika, Vol. 34, No. 4, pp. 472–476, April, 1991. 相似文献
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《Waves in Random and Complex Media》2013,23(2):128-142
Abstract By the use of the reduced Rayleigh equation for the amplitude of a surface plasmon polariton on a one-dimensional randomly rough metal surface that is in contact with vacuum, we calculate the dispersion and damping of the surface electromagnetic wave to the lowest nonzero order in the rms height of the surface. It is found that the frequency of the surface plasmon polariton is depressed by the surface roughness. The attenuation of the surface plasmon polariton in the long wavelength limit is due primarily to its scattering into other surface plasmon polaritons, while in the short wavelength limit it is due primarily to its roughness-induced scattering into volume electromagnetic waves in the vacuum. The energy mean free path of the surface plasmon polariton is shorter on a randomly rough metal surface than it is on a lossy planar metal surface, and the surface plasmon polariton is more tightly bound to a rough surface than to a planar one. 相似文献
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介绍了双向反射分布函数(BRDF)的绝对测量原理和方法,选用光谱分辨率为3 nm的光谱辐射度计及精度为001°的三维转角系统,搭建了BRDF自动测量平台,对空间目标表面包覆材料在400—2500 nm的光谱BRDF进行了测量.结果表明,BRDF曲线极大值所对应的散射角度一般在镜反射方向左右,其余BRDF值随散射角变化很平缓,从中间向两边逐渐变小,近似成余弦分布.测量误差为495%.应用模拟退火算法,结合BRDF五参量统计模型,获得了测量光谱范围内各波长对应的共2101组五参量值,通过对比参量计算结果和
关键词:
双向反射分布函数
绝对测量
误差分析
参量模型 相似文献
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Based on the three-component assumption that the reflection is divided into specular reflection,directional diffuse reflection,and ideal diffuse reflection,a bidirectional reflectance distribution function(BRDF) model of metallic materials is presented.Compared with the two-component assumption that the reflection is composed of specular reflection and diffuse reflection,the three-component assumption divides the diffuse reflection into directional diffuse and ideal diffuse reflection.This model effectively resolves the problem that constant diffuse reflection leads to considerable error for metallic materials.Simulation and measurement results validate that this three-component BRDF model can improve the modeling accuracy significantly and describe the reflection properties in the hemisphere space precisely for the metallic materials. 相似文献
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