共查询到20条相似文献,搜索用时 78 毫秒
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运用微扰法研究了平面波入射分层介质粗糙面的电磁散射,推出了不同极化状态下的双站散射系数公式.采用二维fBm分形粗糙面来模拟实际的分层介质粗糙面,结合二维fBm分形粗糙面的功率谱导出了平面波入射二维fBm分形分层介质粗糙面的散射系数计算公式.通过数值计算得到了HH极化下双站散射系数随散射角的变化曲线,讨论了分维、底层介质介电常数、中间介质介电常数和厚度及入射波频率对双站散射系数的影响,得到了二维fBm分形分层介质粗糙面散射系数的分维特征、基本特征、分区特征和随频率变化的特征.
关键词:
电磁散射
二维fBm分形粗糙面
分层介质
微扰法 相似文献
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提出了快速计算二维导体粗糙面与面上金属目标复合散射的广义稀疏矩阵平面迭代及规范网格法(G-SMFSIA/CAG).推导了二维导体粗糙面与面上目标相互作用的耦合积分方程,用稀疏矩阵平面迭代及规范网格法(SMFSIA/CAG)求解粗糙面部分的表面积分方程,而用基于RWG基函数的矩量法(MOM)计算目标部分的表面积分方程,并通过更新方程的激励项迭代求解目标与粗糙面的相互耦合作用.结合Monte-Carlo方法产生具有PM(Pierson-Moskowitz)海浪谱的随机海洋粗糙面,数值分析了海面上不同形状导体目
关键词:
复合散射
广义稀疏矩阵平面迭代及规范网格法
随机海洋粗糙面
双站散射系数 相似文献
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利用基于电流计算的矩量法结合高频算法基尔霍夫近似的混合算法,分析了一维PM谱粗糙海面及其上方二维无限长任意截面导体目标的双站复合电磁散射特性.混合算法将粗糙面和目标分别划分到KA区域和MOM区域,由于无需数值求解粗糙海面区域的表面极化电流,该算法的运算时间和对计算机内存的需求主要取决于粗糙面上方目标的网格划分情况.数值结果以无限长导体圆柱为例计算了其与一维下垫PM谱粗糙海面的复合双站散射截面,并将计算结果与经典MOM结果进行了比对和验证,结果表明混合方法具有较高的计算效率.最后应用混合方法讨论了不同极化状态、海上不同风速以及目标不同尺寸和位置对复合散射截面的影响.
关键词:
粗糙海面
电磁散射
混合算法
矩量法 相似文献
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三维随机粗糙面与目标复合电磁散射的FDTD方法 总被引:1,自引:0,他引:1
用时域有限差分方法(FDTD)研究三维周期性延拓的随机粗糙面与上方目标复合电磁散射.用周期性延拓消除数值计算中截取有限大小粗糙面产生的边缘效应,讨论一个周期单元粗糙面的边长与其相关长度之间的关系.给出在FDTD方法中向粗糙面加载入射波的方法,建立了粗糙面上单个三维目标的复合散射FDTD计算模型.数值结果给出粗糙面与目标散射的近场分布,应用近远场变换得到全方位散射角的双站散射系数.比较了三维与二维散射模型的区别.结果显示当粗糙面上放置目标时,其后向散射显著增强. 相似文献
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提出一种解析的随机泛函方法(SFA),计算导体Gauss粗糙面上三维导体目标的复合电磁散射.推导粗糙面的随机Green函数,用一种新的四路径模型描述面体复合散射机理,用SFA求解双站差场雷达散射截面.以导体球目标为算例,与其他数值计算方法比较后验证了SFA的有效性与准确性,同时讨论了粗糙度、体目标尺寸以及距离粗糙面高度等参量变化对结果的影响,给出复杂形状体目标的双站差场雷达散射截面的空间角分布.
关键词:
随机泛函方法
粗糙面随机Green函数
差场雷达散射截面
面体复合散射 相似文献
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The shower shape of n, n^-, p, p^-, K^+, π^+ and photons, generated by JPCIAE code for 5.5 TeV/A ^208pb+^208pb collisions, incident on the ALICE photon spectrometer (PHOS), is analyzed with the principal component analysis (PCA) method. The efficiency dependence of purity for the photon discrimination is simulated for the deposited energy ranges 0.5-2 GeV, 2-10 GeV, 10-50 GeV and 50-100 GeV. The result shows that in the energy range of 0.5 to 100 GeV, the efficiency of the photon identification can reach 90% with purity of 90%. 相似文献
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E. O. Alt 《Czechoslovak Journal of Physics》1974,24(11):1225-1231
The three-nucleon system for energies below the breakup threshold is investigated with the help of the quasiparticle method. Two types of local potentials are used, namely purely attractive Yukawa potentials and the soft-core potentials of Malfliet and Tjon. The results obtained are compared with those of other calculations employing different methods.Presented at the symposium Theory of lightest nuclei, Liblice, Czechoslovakia, May 1974. 相似文献
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The shower shape of n,n,p,p,K+,π+ and photons,generated by JPCIAE code for 5.5 TeV/A 208Pb+208Pb collisions,incident on the ALICE photon spectrometer(PHOS),is analyzed with the principal component analysis(PCA) method.The efficiency dependence of purity for the photon discrimination is simulated for the deposited energy ranges 0.5-2 GeV,2-10 GeV,10-50 GeV and 50-100 GeV.The result shows that in the energy range of 0.5 to 100 GeV,the efficiency of the photon identification can reach 90% with purity of 90%. 相似文献
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U. Köster 《The European Physical Journal A - Hadrons and Nuclei》2002,15(1-2):255-263
For fifty years the isotope separation on-line (ISOL) technique has been used for the production of radioactive-ion beams
(RIBs). Thick-target ISOL facilities can provide very intense RIBs for a wide range of applications. The important design
parameters for an ISOL facility are efficiency, rapidity and selectivity of all steps of the separation process. To achieve
the anticipated beam intensities with the next-generation RIB facilities, the production rate in the ISOL target has to be
increased by orders of magnitude. This is only possible by adapting the projectile beam for optimum production cross-sections
and simultaneously minimizing the target heating due to the electronic stopping power of charged-particle projectiles. ISOL
beams of 75 different elements have been produced up to now and further beam development is under way to produce a still greater
variety of isotopes and to improve existing beams in intensity and purity.
Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002
RID="a"
ID="a"e-mail: Ulli.Koster@cern.ch 相似文献
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Condition are derived for the approximate focusing of diffraction lines in the chosen, relatively wide angular region, using the semi-focusing method with a flat sample, if a bent crystal monochromator is employed. The form of the absorption factor for a flat polycrystalline sample is derived for the case of uniform oscillation of the sample in the angular region ± around the axis of the camera.
, . ± , .相似文献
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The properties of the six-nucleon system are examined with a multi-configuration resonating-group method consisting of thed+ configuration, thep+5He andn+5Li configurations, and deuteron pseudo-inelastic configurations. The main purpose is to study the reaction mechanisms in this system. The results obtained are quite satisfactory, with the calculatedd+ total reaction cross sections equal to around 90% of the empirically determined values. The one-nucleon transfer process turns out to be significantly more important than the deuteron direct-breakup process; however, the latter process must still be properly taken into consideration, since it does contribute to about one third of thed+ total reaction cross section. The process of one-nucleon transfer is shown to occur mainly in the peripheral region, while the process of deuteron direct-kreakup is found to take place predominantly in the interior region of the compound nucleus. The convergence property with respect to the number of deuteron pseudo-inelastic configurations has also been investigated. Here it is found that, with the dominant configurations included, the number of such configurations required can be rather small, which is an important finding because it greatly simplifies the computational aspects of multi-configuration resonating-group calculations. 相似文献
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We report the reproducible folding of the 20 amino-acid protein trp cage using a novel version of the stochastic tunneling method and a recently developed all-atom protein free-energy force field. Six of 25 simulations reached an energy within 1 kcal/mol of the best energy, all of which correctly predicted the native experimental structure of the protein, in total eight simulations converged to the native structure. We find a strong correlation between energy and root-mean-square deviation to the native structure for all simulations. 相似文献
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G. Puddu 《The European Physical Journal A - Hadrons and Nuclei》2007,34(4):413-415
We compare the recent exact and coupled-cluster calculations (Phys. Rev. Lett. 98, 112501 (2007)) of energy levels using the GXPF1A Hamiltonian modified with variable shell gap with the corresponding results
obtained with the hybrid multi-determinant scheme. We show that the hybrid multi-determinant scheme is highly cost-efficient
and very accurate for several angular momenta and variable shell gap of the f5/2, p3/2, p1/2 shells relative to the f7/2 shell. 相似文献
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Bursting oscillation in CO oxidation with small excitation and the enveloping slow-fast analysis method 下载免费PDF全文
Based on the traditional scheme for a nonlinear system with multiple time scales,the enveloping slow-fast analysis method is developed in the paper,which can be employed to investigate the dynamics of nonlinear fields with multiple time scales with periodic excitation.Upon using the method,the behaviors of the kinetic model of CO oxidation on the platinum group metals have been explored in detail.Two typical bursting phenomena such as Fold/Fold/Hopf bursting and Fold/Fold bursting,are presented,the bifurcation mechanisms of which have been obtained.Furthermore,the dynamic difference between the two cases corresponding to relatively large and small perturbation frequencies,respectively,has been presented,which can be used to describe the influence of the frequencies involving in the evolution on the bursting behaviors in the system. 相似文献