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.

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.

冷储备系统的动态结构变化使得系统可用度分析必须基于瞬态求解，针对频域两部件冷储备系统马尔可夫更新方程解算困难的问题，提出基于时域伏尔特拉方程的迭代算法，证明了该迭代方程的唯一性和收敛性，并培出选代算法的误差分析。理论和实例分析表明，当冷储备系统部件的工作寿命和维修时间分布是有界函数时，利用迭代算法可以容易实现时域马尔可夫更新方程的求解。

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.

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.