大气气溶胶对激光制导探测作用距离影响的数值分析

针对大气气溶胶辐射传输衰减效应是影响1.06μm激光武器系统性能的重要因素,探讨了大气气溶胶对1.06μm激光探测作用距离的影响,构建了激光制导波段探测作用距离模型,并在此基础上进行激光探测作用距离的大气气溶胶影响数值仿真。试验表明,基于该模型计算的大气透过特性准确度基本符合国际公认理论分析值,对作用距离的评估结果与客观实际基本相符,对最大限度分析利用战场气象环境以确保武器作战性能的充分发挥具有重要价值,可为激光探测作用距离的气象环境影响后续发展奠定一定基础。     

Influence of propagation direction on operation performance of rotating detonation combustor with turbine guide vane

Due to the pressure gain combustion characteristics, the rotating detonation combustor (RDC) can enhance thermodynamic cycle efficiency. Therefore, the performance of gas-turbine engine can be further improved with this combustion technology. In the present study, the RDC operation performance with a turbine guide vane (TGV) is experimentally investigated. Hydrogen and air are used as propellants while hydrogen and air mass flow rate are about 16.1 g/s and 500 g/s and the equivalence ratio is about 1.0. A pre-detonator is used to ignite the mixture. High-frequency dynamic pressure transducers and silicon pressure sensors are employed to measure pressure oscillations and static pressure in the combustion chamber. The experimental results show that the steady propagation of rotating detonation wave (RDW) is observed in the combustion chamber and the mean propagation velocity is above 1650 m/s, reaching over 84% of theoretical Chapman-Jouguet detonation velocity. Clockwise and counterclockwise propagation directions of RDW are obtained. For clockwise propagation direction, the static pressure is about 15% higher in the combustor compared with counterclockwise propagation direction, but the RDW dominant frequency is lower. When the oblique shock wave propagates across the TGV, the pressure oscillations reduces significantly. In addition, as the detonation products flow through the TGV, the static pressure drops up to 32% and 43% for clockwise and counterclockwise propagation process respectively.     

耐1200℃陶瓷瓦重复使用性能

针对目前比较成熟的耐1 200℃陶瓷瓦开展了1 200℃多次重复热处理,研究了陶瓷瓦的结构和性能演变行为和重复使用性能。结果表明:1 200℃热处理20次后,耐1 200℃陶瓷瓦表现出良好的宏观热稳定性;重复热处理过程中,纤维间烧结,黏接熔融和石英纤维析晶及晶粒长大,使纤维直径发生变化,出现缩颈,进而导致了Z向收缩,收缩率达14%,从而使得压缩强度略有增大,隔热性能降低;经过1 260℃、11次单面辐射加热后,Z向收缩率为5.58%,隔热效果降低了7.59%,但隔热材料能够在6次重复加热后保持材料隔热性能不降低。     

人工造雾成雾过程微物理性能分析

通过对人造雾宏观性能和微物理性能变化过程的观测与分析,研究了人造雾成雾过程和成雾机理,并结合对云雾生长理论的分析比较了实际雾滴粒径分布范围、生长时间等与理论计算结果的异同。结果显示人造雾的雾滴粒径和生长时间与理论计算结果基本相符,但其具体的生长过程与理论过程有所差别;人造雾与天然雾相比,雾滴数密度稍大,但雾滴粒径和含水量稍小,雾滴谱分布特点有所不同。     

防空导弹制导雷达综合抗干扰能力评估

分析了地空导弹武器系统制导雷达面临的主要干扰及其所采取的主要抗干扰措施,一般层次分析法(AHP)在评估某些模糊概念时存在缺陷。基于模糊层次分析法(FAHP),构造了模糊一致判断矩阵,建立了防空导弹制导雷达综合抗干扰能力评估模型,该模型具有快速、易于操作等优点,解决了在评价制导雷达综合抗干扰能力时难以定量分析的问题。     

高超声速飞行器保预设性能的反演控制方法

为了解决高超声速飞行器纵向运动模型的稳定轨迹控制问题,设计了一种在非仿射模型基础上保证预设性能的反演控制方法。对于速度子系统,直接设计非仿射控制律,保证预设性能,通过合理的变换将高度子系统转化为严格的反馈形式,便于反演控制步骤的设计。基于动态性能和稳态精度,设计了预设性能函数,将跟踪误差的稳定性限制在预设范围内,引入指令滤波器,有效克服了传统反演控制中虚拟信号重复推导的问题。控制器的设计不依赖于精确的模型。引入径向基函数来逼近过程中的未知函数,使得控制律具有令人满意的鲁棒性和实用性。基于李雅普诺夫稳定性理论,证明了所有闭环系统的稳定性。仿真结果表明,该控制器能够稳定地跟踪参考信号。     

基于Petri网的C2S性能分析方法研究

给出了用时间连续随机Petri网和时间离散随机Petri网计算系统稳态概率的方法,并将其应用于指挥控制系统(C2S)的性能分析中,分析结果表明这种计算方法是可行的。     

Analysis of a production system in a general configuration

We consider a production system comprising multiple stations (or workshops) such as an entry station, a set of work stations, a central station, and an exit station, which are arranged in a general configuration. A worker (or a vehicle tool) is assigned to each station, who sends a part from the station to the destination station according to the required process path of the part. Any part is allowed to visit a work station more than once if its process path requires. We propose a new control strategy with the push policy for instructing each worker to send a part and the kanban mechanism for controlling the work‐in‐process (WIP) in each work station. As all work stations have limited local buffers, the central station is used for storing blocked parts temporarily. Such a production system is modeled as an open queueing network in a general configuration with a Markovian part sending policy and a machine no blocking mechanism. The queueing network is analytically characterized. Some important performance measures are compared with other control strategies. A semi‐open decomposition approach is applied to the queueing network for computing the blocking probabilities when parts arrive at the work stations. An algorithm is developed based on the semi‐open decomposition approach. Numerical experiments show the quality of the solutions obtained by the algorithm as well as a property of a performance measure. © 2001 John Wiley & Sons, Inc. Naval Research Logistics 48: 128–143, 2001     

Economic design of a two-stage control chart based on both performance and surrogate variables

The traditional approach to economic design of control charts is based on the assumption that a process is monitored using only a performance variable. If, however, the performance variable is costly to measure and a less expensive surrogate variable is available, the process may be more efficiently controlled by using both performance and surrogate variables. In this article we propose a model for economic design of a two-stage control chart which uses a highly correlated surrogate variable together with a performance variable. The process is assumed to be monitored by the surrogate variable until it signals out-of-control behavior, then by the performance variable until it signals out-of-control behavior or maintains in-control signals for a prespecified amount of time, and the two variables are used in alternating fashion. An algorithm based on the direct search method of Hooke and Jeeves [6] is used to find the optimum values of design parameters. The proposed model is applied to the end-closure welding process for nuclear fuel to compute the amount of reduction in cost compared with the current control procedure. © 1999 John Wiley & Sons, Inc. Naval Research Logistics 46: 958–977, 1999     

采用M阶正交信号的DS-CDMA系统性能分析

随着移动通信的迅速发展 ,码分多址技术受到越来越多的关注。为了提高系统的抗干扰性能 ,在CDMA系统中采用了M阶正交信号。通过分析采用M阶正交信号的DS CDMA系统基带接收信号的统计性能 ,文中得出了多址、多径干扰下系统的误码率计算公式 ,并详细分析了系统的抗干扰性能。