Fast method for SAR echo simulation of a three-dimensional ground scene

Due to huge calculation of SAR echo simulation of a three-dimensional (3D) ground scene, a fast simulation method is proposed. First, the data of a 3D ground scene are fractionally interpolated based on the Fractional Brownian Motion (FBM) model. Second, the data interpolated are divided into lots of small facets whose precision meets the simulation requirement, the backscattering coefficients of the small facets are calculated. Third, the shaded area is judged by the comparison method of overlook angles. Three parallel levels are analyzed and the kernel function is designed. Finally, the computing method of reduction adding and external thread are also utilized under the framework of GPU in order to get high efficiency. With the methods mentioned above, the imaging result of experimental DEM data verifies the validity and superiority of the proposed method.     

复杂理论视阈下动态课堂场域的控制与自主研究

文章从复杂理论的角度分析了课堂教学过程是一个复杂的动态适应过程,是教师和学生之间的"复杂对话".从而指出课堂教学的动态性和复杂性,要求教师在课堂场域把握教学过程的复杂性、实现目标与教学模式的匹配、拥有必要的理解力和课堂管理技能,帮助学生实现自主学习,并最终实现课堂教学过程的最优化.     

基于MRIO与SNA的中国水资源空间转移网络分析

基于2002年、2007年和2012年的多区域投入产出表的相关数据,利用多区域投入产出(MRIO)模型和社会网络分析法(SNA)分析了中国水资源流动网络的空间关联性和结构特征。结果表明:网络中的链接数量没有随水足迹贸易值的增加而增加,链接路径上的流量不断增加,网络的韧性不够,空间关联渠道有待拓展,存在一定的等级差异,稳定性需要加强;网络中一些省份链接的增加,会削弱其他省份的链接数目,这种可塑性特征有利于在全国范围内合理配置水资源;将网络划分为4个板块,板块间的溢出关系主要是以板块内部为主,且少数板块之间没有任何的溢出关系。     

Solution of the Problem of an Acoustically Transparent Body in a Far Field

A solution to the problem of realization of an acoustically transparent body in a far field is proposed using active quenching of the diffracted field by quenching means placed on the surface of the body.     

Means for Increasing the Sensitivity of Acoustic Probing when Studying the Structure of Metals

As exemplified by the use of different approaches to processing the results of probing metals with elastic waves, means have been studied for increasing the sensitivity of the ultrasonic method. Representing processes that determine the effect that a medium has on the parameters of an elastic wave by a statistical model in the form of a Dirichlet distribution makes it possible to numerically characterize changes in the structure of a probing pulse and to improve the understanding of phenomena that occur when an elastic wave interacts with a medium, with the degree of material damage taken into account.     

Simulation of the Spatial Distribution of the Local Quantum Efficiency and Photoelectric Characteristics of Photodiode-Based Infrared Focal Plane Arrays

The results of calculation of the spatial distribution of the local quantum efficiency over the area of photodiode-based IR focal plane arrays (IR FPA) are presented. The diffusion of photogenerated charge carriers in the absorber layer of the array was calculated by Monte-Carlo simulation. Methods of reducing the amount of necessary calculations based on using the symmetry properties of the array are discussed. Requirements for the photoelectric and design parameters (absorber-layer thickness, chargecarrier diffusion length and optical absorption length in this layer, the ratio of the size of n–p junctions to the geometrical dimensions of the detector pixels) are formulated that ensure the threshold sensitivity and spatial resolution of IR FPAs.