Xu Minqiang

Bayesian model‐based fault diagnosis for the rotor

Purpose – The purpose of this paper is to deal with the fault of the rotor system of aeroengine that has too much uncertainty and design a structural diagnosis framework for the rotor.Design/methodology/approach – Bayesian network (BN) is especially suited for capturing and reasoning with uncertainty. This paper adopts the techniques of BN to implement the probability computation of fault occurrence using system information. The rotor system is analyzed in detail and the familiar faults and their corresponding fault symptoms are extracted, then the rotors BN model based on above information is established. Meanwhile, a framework of the fault diagnosis system based on the network model is developed. Using this model, the conditional probabilities of the faults happened are computed when the observation of the rotor is presented.Findings – The diagnosis methods developed are used to diagnose the actual four kinds of faults of the rotor. The BN model can identify the faults occurred by those probabilities c...

Multiple scattering and dynamic stress analysis of elastic waves in a fiber-reinforced composite with interfaces

Based on the theory of elastic dynamics, multiple scattering of elastic waves and dynamic stress concentrations in fiber-reinforced composite are studied. The analytical expressions of elastic waves in different regions are presented. The mode coefficients of elastic waves are determined in accordance with the continuous conditions of displacement and stress on the boundary of the multi-interfaces. By using the addition theorem of Hankel functions, the formula of scattered wave fields in different local coordinates are transformed into those in one local coordinate to determine the unknown coefficients and dynamic stress concentration factors (DSCFs). The influences of the distance between two inclusions, material properties and structural size on the DSCFs near the interfaces are analyzed. As examples, the numerical results of DSCFs near the interfaces for two kinds of fiber-reinforced composites are presented and discussed.

An Anomaly Detection Algorithm of Satellite Power System Based on CUSUM Control Chart

According to the characteristics of the power supply subsystem, this paper proposes a CUSUM control chart approach to tackle the anomaly detection and fault early warning for the satellite power supply subsystem. Firstly, through the comparison and analysis about satellites remote sensing data, this paper selects power hydrogen pressure value as a characteristic. Secondly, this paper establishes the CUSUM control chart of the power hydrogen pressure, and then detects anomaly in the satellite power system using this CUSUM control chart. Analysis of satellite telemetry data shows that when the satellite state is abnormal, the value of the characteristic will be changed and this can be recognized by the method presented in this paper, as well as the fault early warning will be given. That achieves the purposes on the satellite power system anomaly detection and fault early warning.

Notice of Retraction Reliability assessment of the system subjected to sudden and multiclass gradual failures

There are many systems which undergo not only sudden failure but also multiclass gradual failures simultaneously. This paper presents an approach to reliability assessment of these systems. Firstly, the system reliability model is given. The sudden failure time is assumed to follow the two-parameter Weibull distribution and the distribution is real-timely updated by the Bayesian estimation approach, and then the reliability model of the system subjected only to sudden failure is obtained. The deterioration of a variable leading to one class of gradual failure is described by a Gamma process and the parameters are real-timely updated by the Bayesian estimation approach, and then the reliability model of the system subjected only to one class of gradual failure is formulated. The results of the numerical example show that the proposed approach is effective for the reliability assessment of the system subjected to sudden and multiclass gradual failure simultaneously.