基于DSP的双伺服驱动系统

针对某型火炮伺服系统的数字化改造,设计了一种基于单片DSP的双伺服驱动系统.本设计利用电机控制专用芯片--TMS320LF2407A,独立输出两路PWM控制信号,分别驱动高低和方位两个伺服电机.功率放大电路采用工作在受限单极倍频可逆PWM控制模式下的H桥结构.试验表明,该数字伺服系统工作可靠、动态响应快、噪音低.     

On the conditional residual lifetime of coherent systems under double regularly checking

In this paper, we consider a coherent system with n independent and identically distributed components under the condition that the system is monitored at time instances t₁ and t₂ (t₁ < t₂). First, various mixture representations for reliability function of the conditional residual lifetime of the coherent system are derived under different scenarios at times t₁ and t₂ (t₁ < t₂). Several stochastic comparisons between two systems are also made based on the proposed conditional random variables. Then, we consider the conditional residual lifetime of the functioning components of the system given that j components have failed at time t₁ and the system has failed at time t₂. Some stochastic comparisons on the proposed conditional residual lifetimes are investigated. Several illustrative graphs and examples are also provided.     

Simulation of the plasticizing behavior of composite modified double-base (CMDB) propellant in grooved calendar based on adaptive grid technology

The frequent occurrence of safety accidents during the calendering process is caused by the flammable and explosive properties of composite modified double-base (CMDB) propellant. Optimization of process parameters with the aid of fluid simulation technology could effectively ensure the safety of the calendering process. To improve the accuracy of the simulation results, material parameters and model structure were corrected based on actual conditions, and adaptive grid technology was applied in the local mesh refinement. In addition, the rheological behavior, motion trajectories and heat transfer mechanisms of CMDB propellant slurry were studied with different gaps, rotational rates and temperatures of two rollers. The results indicated that the refined mesh could significantly improve the contour clarity of boundaries and simulate the characteristics of CMDB propellant slurry reflux movement caused by the convergent flow near the outlet. Compared with the gap, the increased rotational rate of roller could promote the reflux movement and intensify the shear flow of slurry inside the flow region by viscous shear dragging. Meanwhile, under the synergistic effect of contact heat transfer as well as convective heat exchange, heat accumulated near the outlet and diffused along the reflux movement, which led to the countercurrent heat dissipation behavior of CMDB propellant slurry. The plasticizing mechanism of slurry and the safety of calendering under different conditions were explored, which provided theoretical guidance and reference data for the optimization of calendering process conditions. Based on the simulation results, the safety of the CMDB propellant calendering process could be significantly improved with a few tests conducted during a short research and development cycle.     

一类广义二重积分

首先利用一个收敛级数构造了R上的一个特殊开集G,然后利用平面点集可求面积的充要条件,在平面上引入了一个有界的不可求面积的积分区域Ω,最后在Ω上定义了一个取正值的分段函数,并证明了其在Ω上的广义二重积分存在。     

双层隔振系统隔振效果研究

隔振系统的隔振效果与被隔离体、中间质量块及基座中的弹性模态有很大的关系.在考虑被隔离体、中间质量块及基座为弹性体的前提下,研究了它们的弹性模态对系统隔振效果的影响,得出了设计隔振系统时要遵循的一些原则.     

弹性支持的无限铁木辛柯梁对移动振动质量的响应

针对具有弹性基础的无限梁在移动的振动质量激励下的响应问题,采用考虑剪切变形和转动惯量的铁木辛柯梁理论建立梁的微分方程,并利用双重傅立叶变换求解,得到梁的运动方程。最后,通过一个数值计算的实例,分析了振动质量以及其移动的速度对梁的响应的影响。结果表明,振动质量本身对梁的响应的影响不可忽视。     

双连杆机构发动机运动学分析

对双连杆机构的运动学进行了理论分析,推导出了活塞的位移、速度和加速度公式及活塞侧连杆和曲轴侧连杆摆角公式,并且针对一实例进行了计算,与相同结构尺寸的传统曲柄连杆机构发动机作了比较分析.     

一种双参数批更换系统的优化问题

研究了一种在更换时间有限的情况下 ,基于交替更新过程的双参数批更换系统的优化问题 ,这一问题的目标是平均费用率的极小化。给出了一种特殊情况的讨论结果。     

The incentive effect of acceptance sampling plans in a supply chain with endogenous product quality

This article studies a firm that procures a product from a supplier. The quality of each product unit is measured by a continuous variable that follows a normal distribution and is correlated within a batch. The firm conducts an inspection and pays the supplier only if the product batch passes the inspection. The inspection not only serves the purpose of preventing a bad batch from reaching customers but also offers the supplier an incentive to improve product quality. The firm determines the acceptance sampling plan, and the supplier determines the quality effort level in either a simultaneous game or a Stackelberg leadership game, in which both parties share inspection cost and recall loss caused by low product quality. In the simultaneous game, we identify the Nash equilibrium form, provide sufficient conditions that guarantee the existence of a pure strategy Nash equilibrium, and find parameter settings under which the decentralized and centralized supply chains achieve the same outcome. By numerical experiments, we show that the firm's acceptance sampling plan and the supplier's quality effort level are sensitive to both the recall loss sharing ratio and the game format (i.e., the precommitment assumption of the inspection policy). © 2013 Wiley Periodicals, Inc. Naval Research Logistics, 2013     

仿真模型的语法可组合问题及组合判定

层次化特征是仿真可组合问题的本质特征之一,首先介绍了仿真可组合问题的基本概念,提出多层次的组合参考模型,以此引出语法层次的可组合问题,进而从命名、顺序及复杂类型匹配三个方面刻画了语法层次仿真模型的组合失配现象.为解决组合失配问题,建立了三类变换条件下的类型等价及子类型匹配关系,并以此为基础构建了语法层次组合相容性及可替换性的判定规则.