结构动力稳定性的若干问题

本文仅就结构动力稳定性问题分类、动力稳定性准则、动力稳定性模型及动力稳定性求解方法作一简略介绍。     

间歇法制合成氨原料气的分析

系统地分析了中型合成氨厂以焦炭为原料制取合成氨原料气的有效能损失与分布情况。从热力学角度剖析了节能的潜力,为工艺改造指出了方向。     

舰用燃气轮机起动失效分析

以舰用燃气轮机为对象,在简述燃气轮机起动过程的基础上,分析其起动失效的各种原因,提出解决的方法,为燃气轮机的操作及维护提供参考．     

船用蒸汽发生器的动态模型与模拟研究

以船舶核动力装置中广泛使用的立式U形管自然循环蒸汽发生器为对象,从其热工水力特点分析出发,建立蒸汽发生器的动态模型,并对其运行模拟及应用进行了研究。     

基于SAT的电路错误定位方法研究进展

随着VLSI芯片复杂度不断增加,功能验证与调试已占到整个芯片设计周期的60%以上。而错误的定位往往消耗大量的时间与精力,因此迫切需要一种高效的方法诊断与定位电路中的错误。针对近年来出现的许多电路错误定位方法,介绍了电路错误诊断方法的分类与工作流程,深入分析了基于SAT的错误定位方法的基本原理;对各种算法进行了概述评论,并简要介绍了在不可满足子式求解方面所做的一些研究工作,而不可满足子式能够显著提高错误定位效率与精度;讨论了电路错误定位技术所面临的主要挑战,并对今后的研究方向进行了展望。     

Disruption management in production planning

We study the problem of recovering a production plan after a disruption, where the disruption may be caused by incidents such as power failure, market change, machine breakdown, supply shortage, worker no‐show, and others. The new recovery plan we seek after has to not only suit the changed environment brought about by the disruption, but also be close to the initial plan so as not to cause too much customer unsatisfaction or inconvenience for current‐stage and downstream operations. For the general‐cost case, we propose a dynamic programming method for the problem. For the convex‐cost case, a general problem which involves both cost and demand disruptions can be solved by considering the cost disruption first and then the demand disruption. We find that a pure demand disruption is easy to handle; and for a pure cost disruption, we propose a greedy method which is provably efficient. Our computational studies also reveal insights that will be helpful to managing disruptions in production planning. © 2005 Wiley Periodicals, Inc. Naval Research Logistics, 2005.     

导弹测试系统中动态激励设备的调速控制与变频器的应用

导弹自动驾驶仪敏感部件功能状态的测试,是导弹实施综合测试内容的重要项目之一。实施敏感部件的测试的前提条件之一,是要有动态激励信号产生。产生动态激励信号的设备是动态激励装置。动态激励装置由驱动电机进行驱动。对驱动调速机构、调速原理以及变频器的应用,做出概要性阐述。     

基于正交试验设计的内燃机缸套和活塞环磨合过程数学模型的建立

在对内燃机缸套和活塞环磨合过程进行试验研究的基础上,提出了基于正交试验设计的内燃机缸套-活塞环磨合过程磨损量和磨合时间的数学模型,并对试验结果进行了多元正交多项式回归分析,进而利用磨合过程的数学模型分析了各影响因素对磨合过程的影响.磨合模型的建立对确定合理的磨合时间和磨合规范,提供了理论和方法的依据.     

Using a birth‐and‐death process to estimate the steady‐state distribution of a periodic queue

If the number of customers in a queueing system as a function of time has a proper limiting steady‐state distribution, then that steady‐state distribution can be estimated from system data by fitting a general stationary birth‐and‐death (BD) process model to the data and solving for its steady‐state distribution using the familiar local‐balance steady‐state equation for BD processes, even if the actual process is not a BD process. We show that this indirect way to estimate the steady‐state distribution can be effective for periodic queues, because the fitted birth and death rates often have special structure allowing them to be estimated efficiently by fitting parametric functions with only a few parameters, for example, 2. We focus on the multiserver M_t/GI/s queue with a nonhomogeneous Poisson arrival process having a periodic time‐varying rate function. We establish properties of its steady‐state distribution and fitted BD rates. We also show that the fitted BD rates can be a useful diagnostic tool to see if an M_t/GI/s model is appropriate for a complex queueing system. © 2015 Wiley Periodicals, Inc. Naval Research Logistics 62: 664–685, 2015     

NCO相位截断对频域抗干扰性能影响分析

频域抗干扰易于工程实现、窄带干扰抑制性能好,是目前全球卫星导航系统(Global Navigation Satellite System,GNSS)抗干扰接收机中广泛采用的抗干扰算法。频域抗干扰接收机普遍采用数控振荡器(numerically controlled oscillator, NCO)生成本振信号。由于硬件约束,通常需要对NCO进行相位截断。而NCO相位截断是否合理对抗干扰性能影响较大。针对该问题,从NCO相位截断导致的本振杂散着手,从理论上分析其对混频和频域抗干扰环节的影响。在此基础上,给出一种NCO查找表地址位宽的理论计算模型,使得接收机的载噪比损耗接近无NCO相位截断的频域抗干扰接收机。仿真表明,抑制带宽大于100kHz、干信比小于80dBc的窄带干扰时,计算的NCO查找表地址位宽不超过10bit。无NCO相位截断的频域抗干扰接收机相比,采用NCO混频的抗干扰接收机的载噪比损耗最多增加0.6dB。