板料冲压成形过程的一种数值模拟方法

在板料冲压成形过程中存在着大变形、大应变,且几何、物理及边界条件三重非线性相互耦合使得计算过程较为复杂.在虚功原理的基础上对板料冲压成形过程的弹塑性有限元分析方法进行了研究,并将有限变形弹塑性有限元法引入板料冲压成形过程,采用更新拉格朗日(ULM, Updated Lagrange Method) 方法描述,推导了有限元列式,建立了板料成形过程的有限元分析模型,开发了分析程序.通过对汽车油底壳的成形模拟说明了模型的正确性.      

多导弹分布式协同制导与控制方法

针对多枚导弹三维空间协同攻击机动目标要求,提出了一种多导弹分布式协同制导与控制方法.基于网络同步原理设计了一种多导弹三维位置同步算法,将目标视作领弹,与攻击导弹组成“领弹-从弹”的拓扑结构,实现了导弹对目标的协同攻击引导.同步算法给出了惯性坐标系导弹3个方向速度的指令,基于坐标变换将其转化为自动驾驶仪可以跟踪的速度及弹道倾角指令.基于切换控制方法设计了导弹自动驾驶仪,实现了多导弹协同制导与控制的闭环仿真.仿真结果验证了该方法的有效性.      

复合材料开孔层压板压缩长期强度预测

Accelerated testing methodology (ATM) predicts long-term strength in low temperature with short-term in high temperature, which is based on the viscoelasticity of matrix and the time-temperature superposition principle (TTSP). The strain invariant failure theory (SIFT) was modified by using micro maximum strain criteria to judge fiber tensile and compressive failure. Master curve of storage modulus of epoxy resin and the time-temperature shift factors were tested from dynamic mechanical analysis(DMA). Master curves of SIFT critical parameters were constructed by tension and compression test for unidirectional carbon fiber reinforced plastics (CFRP) under various temperatures with the time-temperature shift factors of matrix resin. Long-term compression strength of open-hole composite laminates was predicted based on SIFT/ATM combined method. The damage process of fiber and matrix was simulated by progressive damage analysis as well. Good agreement between numerical results and experiments was observed, which demonstrates the applicability of this method.     

结合短帧优先的权重轮询AFDX端系统发送策略

提出一种新型的端系统虚链路调度（VL）策略,该策略在短帧优先基础上结合权重轮询（WRR）进行调度,既确保了重要短帧的优先级又可以平衡其他不同优先级信号的延迟上限。应用网络演算理论推导了基于该新型调度策略的端系统不同虚链路的延迟上界,研究了最大延迟上界与不同权重比及其帧长之间的关系,并建立了基于OPNET的航空电子全双工交换式以太网（AFDX）网络模型,仿真分析新型调度策略与短帧优先、带权重轮询调度算法下端系统数据的发送延迟。结果表明,该新型调度策略有效可行,降低了短帧虚链路的最大延迟时间,提高了长帧数据中较重要任务数据的处理带宽,适用于具有较多重要短帧并具有不同优先级数据的机载系统网络。      

Type synthesis of 2-DoF rotational parallel mechanisms actuating the inter-satellite link antenna

This paper focuses on the type synthesis of two degree-of-freedom (2-DoF) rotational parallel mechanisms (RPMs) that would be applied as mechanisms actuating the inter-satellite link antenna. Based upon Lie group theory, two steps are necessary to synthesize 2-DoF RPMs except describing the continuous desired motions of the moving platform. They are respectively generation of required open-loop limbs between the fixed base and the moving platform and definition of assembly principles for these limbs. Firstly, all available displacement subgroups or submanifolds are obtained readily according to that the continuous motion of the moving platform is the inter-section of those of all open-loop limbs. These subgroups or submanifolds are used to generate all the topology structures of limbs. By describing the characteristics of the displacement subgroups and submanifolds intuitively through employing simple geometrical symbols, their intersection and union operations can be carried out easily. Based on this, the assembly principles of two types are defined to synthesize all 2-DoF RPMs using obtained limbs. Finally, two novel categories of 2-DoF RPMs are provided by introducing a circular track and an articulated rotating platform, respectively. This work can lay the foundations for analysis and optimal design of 2-DoF RPMs that actuate the inter-satellite link antenna.     

FMMR微推进系统推力测量装置研究

为了对自由分子流微型电阻加热推力器(FMMR)微推进系统的性能进行试验研究,设计了一个基于天平原理的微推力测量装置,装置采用微推力器自重与推力相分离、触点式外接供电和推进系统集成方法,有效消除了供电电缆和推进剂供应管路的影响.结果表明,测量精度可达±8％,能够满足mN级微小推力测量的精度要求;同时,通过对结构进行一定改...     

基于坐标变换原理的最小区域法评定空间直线度误差

介绍了一种用基于坐标变换原理的最小区域法评定空间直线度误差的算法,并且给出了数学模型和计算实例.     

谈“谨慎性”会计原则

谨慎性原则是财务会计为合理界定财产受托管理人的经营责任而发展起来，它反映了会计人员对他们所承担的责任所持的一种态度。谨慎性原则在各国的会计实务中都有不同的体现。我国从1993年后开始在实务中引入“谨慎性”原则。至2000年颁布并于2001年1月1日起实施的《企业会计制度》中，体现谨慎原则的政策已随处可见。本文就谨慎性原则及其在我国会计实务中的运用以及其自身的局限性进行了探讨。     

结合试飞特点,开展专用测试设备计量确认

根据我院专用测试设备计量确认现状及需求，对开展试飞专用测试设备计量确认工作的要求，步骤、确认原则，以及编定计量确认方法进行了必要的讨论分析。     

合理选择示波器

介绍了模拟示波器、数字储存示波器、数字荧光示波器三代示波器的定义、结构原崐理、优缺点。对合理选择示波器的问题进行了讨论。