阐述了复合大系统(system of systems,SoS)的特点及基于仿真的性能分析需求,介绍了传统的自底向上和自顶向下两种基本系统仿真方法,并分析了各自的优缺点。在对状态图、随机状态图和代理模型等基本概念介绍的基础上,提出了一种新的适应于SoS性能分析的仿真方法,并通过一个弹道导弹预警信息系统仿真案例对新方法的可行性进行了验证。
The optimal estimation performance of target parameters is studied. First, the general form of Cramer-Rao bound(CRB)for joint estimation of target location and velocity is derived for coherent multiple input multiple output(MIMO) radars. To gain some insight into the behavior of the CRB, the CRB with a set of given orthogonal waveforms is studied as a specific case. Second, a maximum likelihood(ML) estimation algorithm is proposed. The mean square error(MSE) of the ML estimation of target location and velocity is obtained by Monte Carlo simulation and it approaches CRB in the high signal-to-noise ratio(SNR) region.
This paper focuses on the performance analysis of flexible reactive systems. The performance analysis consists of two phases: first system modeling, second performance evaluation. The paper models the flexible reactive system by the stochastic statecharts method, and uses the simulation method to evaluate the performance. To make use of the feature of eventtriggered state transitions in the statecharts, a new method of simulation is proposed based on the techniques of the discreteevent system simulation. The new method solves the problem of computer implementation of stochastic events, probabilistic transition, concurrent states, parallel actions, and broadcast communication mechanism in the stochastic statecharts. An example of a flexible manufacturing system is presented. The simulation result of the example is consistent with the analytical result, which shows the feasibility of the proposed new simulation method.
This paper studies the estimation performance of the coherent processing parameter(CPP), including time delay differences and phase synchronization errors among different apertures of the distributed coherent aperture radar(DCAR). Firstly,three architectures of signal processing in the DCAR are introduced. Secondly, the closed-form Cramer-Rao bound(CRB) of the CPP estimation is derived and compared. Then, the closed-form CRB is verified by numerical simulations. Finally, when the next generation radar works in a fully coherent mode, the closed-form signal-to-noise ratio(SNR) gain of the three architectures is presented.
