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针对已搭建的非对称空间外差光谱仪开展地基风场模拟探测研究,验证该仪器进行中高层大气风场的探测精度水平.介绍了非对称空间外差光谱技术进行风场探测的基本原理以及研制的光谱仪基本性能参数,设计了风速模拟装置开展风场模拟探测实验,并对风速模拟过程中电机转速、安装机械角度、转盘半径测量值、光线入射角度等不确定因素进行了分析和计算,该装置模拟的理论风速误差不高于1.3%,能够满足风场模拟探测验证要求.利用该风速模拟装置并通过调节不同电机转速实验,获得了模拟风速在34.19~78.63m/s内的24组测量数据,模拟覆盖了中高层大气风速范围,对测量数据进行误差修正及风速反演处理,非对称空间外差光谱仪实测风速结果与理论模拟风速对比后得出了风速误差标准差3.28m/s的风速探测精度,有效验证了非对称空间外差光谱技术开展风场探测具有相位灵敏,精度高等特点. 相似文献
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为了快速模拟高能质子照相过程,利用蒙特卡罗(MC)技术和技巧编写了程序QMCPrad,并开展了QMCPrad与MCNPX的对比计算以及实验E955的模拟验证工作。在模型选取中,修改核反应过程权重的隐式俘获模式和一次抽样模拟穿透客体的多次库仑散射的浓缩历史方式都节约了大量的计算时间。与MCNPX相比,QMCPrad具备模拟质子在磁透镜中输运过程的能力。QMCPrad与MCNPX、实验E955的对比及验证结果表明,QMCPrad能够准确定量地模拟高能质子照相,为质子照相实验设计提供工具。 相似文献
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《物理学报》2021,(14)
自动微分是利用计算机自动化求导的技术,最近几十年因为它在机器学习研究中的应用而被很多人了解.如今越来越多的科学工作者意识到,高效、自动化的求导可以为很多科学问题的求解提供新的思路,其中自动微分在物理模拟中的应用尤为重要,而且具有挑战性.物理系统的可微分模拟可以帮助解决混沌理论、电磁学、地震学、海洋学等领域中的很多重要问题,但又因为其对计算时间和空间的苛刻要求而对自动微分技术本身提出了挑战.本文回顾了将自动微分技术运用到物理模拟中的几种方法,并横向对比它们在计算时间、空间和精度方面的优势和劣势.这些自动微分技术包括伴随状态法,前向自动微分,后向自动微分,以及可逆计算自动微分. 相似文献
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验证、确认与不确定度量化(VVUQ)是评估物理模型可信度和量化复杂工程数值模拟结果置信度的系统方法.验证是要回答数值模拟程序是否正确求解了物理模型和程序是否正确实施或给出求解模型的误差、不确定性大小及使用范围,确认是要通过数值结果回答物理模型是否反映了真实客观世界或反映真实客观世界的可信程度.文章围绕爆轰流体力学模型,剖析了模型中不确定性因素,给出了影响模拟结果不确定性的关键因素清单,并对其开展了敏感度分析,确认了模型的适应性. 相似文献
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人类作为信息交流的主要信息产生源和信息接收槽,语言声学、心理声学和生理声学在信息技术中发挥着越来越重要的作用。作为声学与信息技术相互渗透的产物-通信声学,近十几年来随着数字信号处理技术的发展,其研究和应用领域得到了很大的扩展。本文在简述通信声学产生和发展的必然性和必要性之后,主要介绍了通信声学目前的研究领域及其应用。 相似文献
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基于计算电磁学中对强迫激励源消除虚假反射的算法分析,提出了用等效电流和等效磁流在FDTD公式中引入电场激励源和磁场激励源的方法。从粒子模拟方法的基本方程和迭代公式出发,分析了激励源的引入过程,推导出激励源所等效的电流项和磁流项表达式,实现了新的激励源设置方法,并进行了数值验证和结果讨论。研究表明:这类等效模型与标准FDTD公式能紧密结合,引入非常方便;不必专门设置一个附加的散射场区来处理散射场的计算,大大节省了计算时间和计算内存,比常规总场/散射场体系方法的效率高20%以上,对粒子模拟这类耗时的计算较为适用。通过对2维柱坐标系下相对论速调管放大器(RKA)的模拟,证明了此类激励源设置方法的实用性。 相似文献
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In this Letter, we generalized the surface integral equation method for the evaluation of Casimir force in arbitrary three-dimensional geometries. Similar to the two-dimensional case, the evaluation of the mean Maxwell stress tensor is cast into solving a series of three-dimensional scattering problems. The formulation and solution of the three-dimensional scattering problems are well-studied in classical computational electromagnetics. This Letter demonstrates that this quantum electrodynamic phenomenon can be studied using the knowledge and techniques of classical electrodynamics. 相似文献
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C. Argyropoulos E. Kallos Y. Hao 《Applied Physics A: Materials Science & Processing》2011,103(3):715-719
In this paper, the transient responses of some devices which are based on transformation electromagnetics are studied, such
as invisible cloaks and concentrators, by using the Finite-Difference Time-Domain (FDTD) numerical technique. In particular,
effects of the inherent losses as well as the coating size of the ideal cylindrical cloak on its bandwidth and cloaking performance
are examined. In addition, it is demonstrated that the performance of transformation electromagnetics based devices is affected
by the material parameters in the design, although they may behave nicely under monochromatic plane wave illuminations. The
obtained results are of interest for the future practical implementation of these structures. 相似文献
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将一等效薄片模型嵌入到时域有限差分算法(FDTD)中,以快速而有效地解决复合材料薄片在电磁计算中的多尺度问题。在该嵌入式薄片模型中,薄片不需要被剖分网格,而是被嵌入到相邻的网格间,从而可以使用相对较大的网格剖分周围物体,进而可节省大量的计算资源。在这一模型中,薄片被等效为一段传输线,并用其频域的导纳矩阵代替。使用数字滤波器理论以及逆Z变换可将频域的导纳矩阵转换到时域,并将其嵌入到时域有限差分算法中。该嵌入式薄片模型被用来计算一单层碳纤维复合材料薄片的反射以及透射性能,并与其解析解进行对比,从而验证该模型的准确性、收敛性以及高效性。该模型被用来计算三种具有不同电参数的单层碳纤维复合材料薄片的屏蔽性能,以研究各电参数对其屏蔽性能的影响。 相似文献
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:本文介绍了国际上关于环境电磁学及电磁兼容技术的一些科研进展情况,描述了电磁兼容的动态,最后并提出了若干建议. 相似文献
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Gen Luo 《Waves in Random and Complex Media》2017,27(3):513-525
In this article, the turbulence structure generated by a propeller is simulated with the computational fluid dynamics (CFD) software FLUENT. With the method of moments, the backscattering radar cross sections (RCS) of the turbulence structure are calculated. The scattering results can reflect the turbulent intensity of the wave profiles. For the wake turbulence with low rotating speed, the scattering intensity of HH polarization is much smaller than VV polarization at large incident angles. When the turbulence becomes stronger with high rotating speed, the scattering intensity of HH polarization also becomes stronger at large incident angles, which is almost the same with VV polarization. And also, the bistatic scattering of the turbulence structure has the similar situation. These scattering results indicate that the turbulence structure can also give rise to an anomaly compared with traditional sea surface. The study of electromagnetic (EM) scattering from turbulence structure generated by the propeller can help in better understanding of the scattering from different kinds of waves and provide more bases to explain the anomalies of EM scattering from sea surfaces. 相似文献
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Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples. 相似文献
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M. Pisarenco J.M.L. Maubach I.D. Setija R.M.M. Mattheij 《Journal of computational physics》2012,231(24):8209-8228
The aperiodic Fourier modal method in contrast-field formulation is a numerical discretization and solution technique for solving scattering problems in electromagnetics. Typically, spectral discretization is used in the finite periodic direction and spatial discretization in the orthogonal direction. In the light of the fact that the structures of interest often have a large width-to-height ratio and that the two discretization approaches have different computational complexities, we propose exchanging the directions for spatial and spectral discretization. Moreover, if the scatterer has repeating patterns, swapping the discretization directions facilitates the reuse of previous computations. Therefore, the new method is suited for scattering from objects with a finite number of periods, such as gratings, memory arrays, metamaterials, etc. Numerical experiments demonstrate a considerable reduction of the computational costs in terms of time and memory. For a specific test case considered in this paper, the new method (based on alternative discretization) is 40 times faster and requires 100 times less memory than the method based on classical discretization. 相似文献
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太赫兹频段下导体表面的细微结构、粗糙度等细节将对目标电磁散射行为产生影响。为衡量这一影响程度,以圆柱导体为例研究了太赫兹频段下目标表面不同结构特征的电磁散射现象及其在图像域的表现规律。利用高频电磁计算方法获得了表面分别为理想光滑、带刻痕和周期粗糙的三种圆柱多姿态角、多频点单站散射场;基于转台成像算法重建了小转角下目标的二维图像。从仿真结果可以看出:m量级的细节特征在太赫兹雷达图像上有着显著的表现,表明太赫兹雷达能够获取更加丰富和精细的目标信息,从而为目标探测识别提供新的特征和技术手段。 相似文献