Advanced computer network can realize the bulk data transfer and real time control with high reliability and precision. Its availability not only depends on the connectivity of topological structure but also resies on its operational performance. Based on new network description, this paper provides the availability model of link and nodes that can be calculated with Generalized Stochastic Petri Net (GSPN). The main contribution of this paper focuses on the routing selection and performance evaluation. Working on the network performance by queueing theory, it concludes that the throughput and time delay are two impurtant performance indices in network. With Power formula, this paper presents the integrated availability model considering both topologic reliability and operational performance, which can realize the availability analysis perfectly from the point of view of a user.

This paper establishes the accelerated life testing model, viz. the hybrid Weibull distribution model under multi-stresses (pressure, velocity and temperature) for typical mechanical product-aerial hydraulic pump. Direct toward the optimization difficulties with multi-parameters in Maximum Likelihood Estimation (MLE), this paper presents an Improved Float Genetic Algorithm (IFGA), which adopts the fuzzy algorithm in the float genetic algorithm to approach the global optimum solution. Application denotes that IFGA not only can obtain the global optimum solution but also can shorten the calculation time greatly.

Accelerated Life Testing (ALT) is an important technique to assess the reliability and lifetime of components with long life and high reliability. To some expensive products, it is difficult to supply a large of samples and long test time to carry out the life testing, so this paper studies accelerated model and its statistical method based on hybrid Weibull distribution under variable synthetic stresses. Based on the cumulative exposure model aforementioned, the parameters of accelerated model can be estimated with ALT data and its accelerated stress profile. However, the development of multi-stresses ALT under variable stress profile leads to a bottleneck problem on parameter estimation when evaluated parameters are greater than three. Direct toward the optimum difficulties with multi-parameters in Maximum Likelihood Estimation (MLE), this paper presents an Improved Float Genetic Algorithm (IFGA), which adopts the fuzzy algorithm in the float genetic algorithm to approach the global optimum solution. Application of hydraulic pump indicates that this method can reduce test time and test samples greatly.

Hydraulic actuation system is typical displacement control system whose performance is subjected to random inputs from noise, random disturbance from pump vibration or parameter changes. Through importing the integral item of residual error in different rank, this paper establishes the Proportion-Integral Observer (PIO) that can eliminate the influence of random input, parameter excursion and inherent disturbance and realize the fault diagnosis robustly. In order to reach the high fault coverage and low false alarm, this paper provides twin-threshold and corresponding fault decision-making strategy that not only considers the inherent noise existed in the system but also can manifest the fault information effectively. Application and simulation of hydraulic actuator system indicates that the adaptive fault diagnosis can detect the failure in high precision at the stochastic condition.

提出了以系统脉冲响应序列作为闭环系统模型的建模方法，并且给出了这种建模方法的计算方法以及模型输出的计算方法。这种闭环系统建模方法保留了脉冲响应序列中的高频成分，避免了从脉冲响应序列向传递晒数变换过程中丢失脉冲响应函数高频信息的缺点；同时，也避免了神经网络每次学习结果获得的网络模型不确定的缺点。采用该方法建立的闭环系统模型精度非常高并且可以应用在故障诊断的系统中。文章最后以数值仿真和实际带随机干扰的系统为例，证明该方法是有效的。