纯模态试验中的作动器/传感器优化配置

基于有效独立法,研究了逐步消减法在纯模态试验作动器/传感器优化配置中的应用。对一给定自由度的结构系统,由系统的模态动能可得系统的F isher信息阵。在优化过程中,根据F isher信息阵可得到各自由度节点所对应的E fI值,由E fI值的大小来确定每次要删除的作动器/传感器。在逐步消减的过程中,把E fI的值表示为一个矩阵的形式,使得优化过程清晰明了,提高了优化效率。最后,通过对一个20自由度的离散悬臂梁的激振器布设进行优化,验证了本文方法的有效性。     

面向微波电力传输的低成本易部署柔性接收天线阵

文章提出了一种用于微波电力传输(MPT)系统的柔性能量接收天线阵列,具有面积大、成本低、易部署的特点。由于能量接收器表面通常为不平整状态,因此,传统刚性材质天线无法完成共形共面制备。为了适应各种外型的运用场景,文章采用柔性材料设计天线,其介质基板和辐射导体分别基于聚酰亚胺和新型液态金属镓铟合金（其中镓的占比为75.5％,铟的占比为245％）。由于MPT应用场景非常复杂多变,故对便携性提出要求。采用折叠/充气展开技术进行结构设计,以实现接收天线阵列收放的便捷性。使用三维电磁场仿真软件（CST）对设计的柔性接收天线从单元到阵列进行仿真,天线工作频点为58GHz。最大捕获效率超过55％,并且在弯曲工况下捕获效率超过35％。仿真结果证明了文章工作的有效性和正确性。     

低能量冲击对碳/环氧复合材料缠绕压力容器的结构损伤及强度影响分析

碳/环氧复合材料缠绕压力容器对外界冲击非常敏感,较低能量的冲击就有可能造成容器结构的严重损伤,进而导致爆破强度的显著降低。国外在碳/环氧复合材料缠绕压力容器低能量冲击研究方面取得了一些试验结果,在对这些试验结果进行综合分析,提炼出了影响冲击损伤效果的相关因素,并分析了这些因素对损伤效果的影响趋势进行了。另外对我国今后开展这方面的相关研究工作提出了一些建议。     

Load balancing strategy and its lookup-table enhancement in deterministic space delay/disruption tolerant networks

Space networks, in which connectivity is deterministic and intermittent, can be modeled by delay/disruption tolerant networks. In space delay/disruption tolerant networks, a packet is usually transmitted from the source node to the destination node indirectly via a series of relay nodes. If anyone of the nodes in the path becomes congested, the packet will be dropped due to buffer overflow. One of the main reasons behind congestion is the unbalanced network traffic distribution. We propose a load balancing strategy which takes the congestion status of both the local node and relay nodes into account. The congestion status, together with the end-to-end delay, is used in the routing selection. A lookup-table enhancement is also proposed. The off-line computation and the on-line adjustment are combined together to make a more precise estimate of the end-to-end delay while at the same time reducing the onboard computation. Simulation results show that the proposed strategy helps to distribute network traffic more evenly and therefore reduces the packet drop ratio. In addition, the average delay is also decreased in most cases. The lookup-table enhancement provides a compromise between the need for better communication performance and the desire for less onboard computation.     

An adaptive integration surface for predicting transonic rotor noise in hovering and forward flights

In this paper, a new permeable adaptive integration surface is developed in order to evaluate transonic rotor noise in accordance with FW-H_pds equations(Ffowcs Williams-Hawkings equations with penetrable data surface). Firstly, a nonlinear near-field solution is computed on the basis of Navier-Stokes equations, which is developed on moving-embedded grid methodology.The solution calculated through the present CFD method is used as the input for acoustic calculations by FW-H_pds equations. Then, two criteria for constructing integration surfaces are established based on the analysis of the quadrupole source strength and the nonlinear characteristic.A new surface is determined adaptively by the pressure gradient or density in a given flowfield,eschewing the uncertainties associated with determining cylinder-shaped integration surfaces. For varying hover cases, transonic noises are simulated with new integration surfaces for a UH-1 model rotor. Furthermore, numerical results of the new integration surface derived from the density perturbation value conform better to experimental data than results derived from the pressure gradient.Finally, the integration surface given by jrqj being 0.1, which is an applicable criterion obtained from hover cases, is used to predict transonic rotor noise in forward flight. The computational accuracy of the new integration surface method has been validated in predicting transonic rotor noise of an AH-1 model rotor at different advance ratios.     

采用改进的CE/SE方法模拟方管中氢氧爆轰波的稳定传播结构

采用改进的时空守恒元/解元（CE/SE）格式和新型二步化学反应模型，对小扰动情况下方管通道中的氢氧气相爆轰传播过程进行了数值模拟，对不同截面尺寸和两种扰动模式下的爆轰波三波线结构进行了详细计算和分析。数值模拟花费了相对较少的计算代价，清晰地得到了方形截面通道中3种相对稳定的爆轰波传播结构，即直角模式、对角模式和螺旋模式。随着截面尺寸的减小，爆轰波胞格图样与波阵面结构随之产生适应性的变形，乃至出现胞格数目的减少和部分三波线的消失；最终，直角模式和对角模式都会转化为顺时针或逆时针的螺旋模式；临界尺寸下，得到了转换过程中新的过渡结构和压力脉冲振幅的变化，并以此初步讨论了直角和对角传播模式的稳定性。     

中继卫星系统仿真软件设计与应用*

设计开发中继卫星系统仿真软件,并针对理想信道条件、I/Q幅相不平衡、幅频特性、群时延、相位噪声、功放饱和条件、非线性信道条件这七种信道,仿真16QAM和16APSK的误码率性能,并对仿真结果进行分析。利用仿真平台得出的非线性信道条件下误码率需求与所需信噪比之间的关系,可以作为完善系统技术指标的重要依据,为中继卫星系统后续建设和应用提供重要参考。     

基于Web的e—CRM系统的分析与设计

首先介绍了CRM和e-CRM的概念,进而提出了基于WEB的六层技术架构,并介绍了各个层次的功能,最后对企业实施e-CRM提出了几点建议,并对CRM发展趋势做了预测。     

柔性转子逆回旋振动特性的研究

论述了具有陀螺效应的柔性转子在各向异性支承条件下回旋振动的特性，推导出了转子在正回旋激励作用下产生逆回旋振动的条件，提出转子振动存在逆回旋带的概念，并举例说明了转子在整个转速范围和振动频率范围内回旋振动的特点，作出了逆回旋带的曲线图。     

基于STEP的CAD/CAPP集成

CAD/CAPP的信息渠成是CIMS的关键技术之一,它的实施必须应用STEP技术。本文介绍了一个基于STEP的CAD/CAPP集成系统,它是通过建立CAD和CAPP之间的信息转换接口,将MPIM和BRCAPP连接起来实现的。MPIM和BRCAPP之间的信息交换方式采用了STEP中性文件交换。