Bounded Error Schemes for the Wave Equation on Complex Domains

This paper considers the application of the method of boundary penalty terms (SAT) to the numerical solution of the wave equation on complex shapes with Dirichlet boundary conditions. A theory is developed, in a semi-discrete setting, that allows the use of a Cartesian grid on complex geometries, yet maintains the order of accuracy with only a linear temporal error-bound. A numerical example, involving the solution of Maxwell’s equations inside a 2-D circular wave-guide demonstrates the efficacy of this method in comparison to others (e.g., the staggered Yee scheme)—we achieve a decrease of two orders of magnitude in the level of the L₂-error.     

On the mechanical behavior of aluminum alloys reinforced by long or short alumina fibers or SiC whiskers

This study was initiated to examine the dispersion of longitudinal and transverse waves in metal matrix composites in order to obtain the dynamic elastic modulus and to evaluate various models for predicting the composite's macroscopic elastic constants from the properties of its constituents. The materials chosen for this investigation were alumina continuous fibers on the one hand and alumina and SiC short fibers on the other hand, all embedded in an aluminum alloy matrix. In addition, some indications have been obtained experimentally for the acoustoelastic effect in the composite.     

单源点法的一种改进

在应用能量线性叠加计算港内不规则波绕射系数时^[1,2]，通过假设不同的计算点具有不同的方向谱，从而增加单源点法考虑地形变化的能力。其中各计算点的方向谱由逆波向线追踪方向确定。本文由此观点建立数学模型。并通过实例计算。来验证这个想法。     

基于宽带毫米波工作体制的雷达目标识别方法探讨

对基于宽带毫米波工作体制的雷达目标特征获取和识别方法进行了综合分析和探讨.表明:在毫米波照射下,雷达目标可模型化为由多个散射中心组成的扩展目标;只要发射信号有足够的带宽,就可以从回波信号中获得各散射中心的空间分布、类型等特征;仿真结果说明,这种方法对高频区复杂目标的识别是有效的.     

四倍频Nd：YAG激光在高压氢气中的喇曼频移研究

利用Nd:YAG固体激光器四倍频输出(266nm)在高压H₂中的受激喇曼散射获得多波长的激光输出。当泵浦能量一定时,通过改变H₂压力得到了最佳的能量输出,299nm波长的激光能量为3mJ,341nm波长的激光能量输出为6.1mJ,398nm波长的激光能量输出为2.8mJ,239nm波长的激光能量输出为0.8mJ,同时在477nm,595nm,218nm,200nm波段也有能量输出。     

三平板剪切干涉仪自动测试系统

三平板剪切干涉仪是环路剪切干涉仪中最简单的一种,它具有基本等光程、剪切量连续可调、两出射光束恒相互平行等特点。利用三平板剪切干涉仪对激光器出射波面质量进行检测,探讨了由剪切干涉图复原原始波面的1阶微分法,编制了专家辅助软件系统,为光机型的三平板剪切干涉仪配置了实时图像采集、处理系统,实现了光、机、电、算相结合,融硬、软件于一体的数字波面剪切干涉仪,并通过实验验证了方法的重复性精度。     

准连续波体制雷达最大熵方法的算法选择

准连续体制作为一种新型雷达体制以其固有的优越性给雷达界带来了巨大的冲击。其数字信号处理系统的开发是进一步完善该体制雷达的关键。本文针对数字信号处理系统中最大熵谱外推电路的算法选择进行了研究。     

Mixture of probability distributions as a basic component in simulating measurement accuracy

A stochastic model is proposed for a basic mechanism in the formation of uncertainties in physical quantity measurements. __________ Translated from Izmeritel'naya Tekhnika, No. 1, pp. 12–17, January, 2006.     

平面药包抛掷爆破的漏斗特征解析

根据惠州港通用码头陆域平面药包抛掷爆破的实爆堆积测量分析成果 ,结合药包设计的主要参数 ,对平面药包产生的爆破漏斗的范围与形态、不同药包部位的残方比与抛掷率、药包的长抗比与圆柱体药包的应力波形演变关系予以解析 ,供硐室爆破的理论研究、模拟试验和总结条形药包特性时参考