Chun Liang Zhang

Fault Diagnosis of Rotating Machinery Base on Wavelet Packet Energy Moment and HMM

A feature extraction method is presented for the fault diagnosis of large rotating machinery to improve the performance of on-line monitoring. According to the characteristics of fault vibration signals, wavelet packet decomposition, a well-known tool to multi-scale analysis, is applied to extracting frequency band energy features; and Hidden Markova Model (HMM) is used to classify. The final feature array is composed of time-domain, amplitude-domain features and wavelet packet energy moment features which reflect the inherent energy distribution characteristics of different faults. The continuous density hidden Markov model (CDHMM) is adopted to recognize the state in on-line monitoring, and the diagnosis success rates are more than 91% to six typical faults on different rotation speeds. The experimental results show the fault diagnosis system is valid and robust, particularly the method of feature extraction.

The Summary of AGV Guidance Technology

AGV is short for automated guided vehicle. AGV is unmanned automated guided carriage car equipped with a non-contact guidance with microcontroller as controlling core and battery as power. The basic functions of the AGV are driving automated, recognizing the site to stop and transfering loads. AGV has been more widely used, because it is a key equipment of flexible manufacturing systems and an important mean of modern logistics systems. Guidance technology is the most critical core technology in AGV system. In this paper the author consult a lot of relevant books and mainly compares principle of a variety of AGV navigation technologies ,analyzes the advantages and disadvantages and forecast the trend of the agv guidance technology development in the future so that relevant researchers can do further research.

A Research on the Stiction and Detection in the Control Valves

Stiction is a common problem in spring-diaphragm type valves, which are widely used in the process industry. A non-invasive method for detecting and quantifying stiction in control valve has been presented in this paper. Although there have been many attempts to understand and detect stiction in control valves, none of the current methods can simultaneously detect and quantify stiction. The method first detects nonlinearity in a control loop by the use of the sensitivity of the normalized bispectrum or bicoherence to the nonlinear interactions that may be present in the control error signal.If nonlinearity is detected, then controlled variable(pv) and controller output(op) signals are filtered using frequency domain wiener filter to obtain filtered pv and op signals.This work describes a model free method that can detect and quantify stiction that may be present in control valves using routine operating data obtained from the process. No additional excitation or experimentation of the plant is required.

Identification of Orientation-Specific Damage Using Guided Waves and Diagnostic Imaging

Guided-waves-based diagnostic imaging techniques have been attracting much attention due to their merits including easily interpretable image, high identification accuracy and suitable for online surveillance. In this study, to envisage the difficulty in detecting orientation-specific damage (crack, notch etc.), a novel guided-waves-based diagnostic imaging technique capable of inspecting complicated engineering structures was developed, in terms of the relationship between damage parameters (location, orientation and severity) and extracted guided waves signal features (time-of-flight, signal correlation and signal energy). Experimental studies were performed to verify the developed diagnostic imaging approach, where a through-thickness crack was successfully identified in a metallic plate and a part of real rail structure respectively.

Finite Element Analysis of the Main Spindle of the Gold Ornaments Chain Forming Device

With Chinas rapid economic development, domestic jewelry consumption has maintained a high growth rate. Jewelery manufacturing equipment is always behind, seriously hampered the development of the industry. For this situation, the author carried out a series of gold automated processing equipment. In this paper, based on the design of a gold-decorated chain molding equipment, using ANSYS software to do finite element analysis on the spindle three-dimensional model of the gold ornaments chain forming equipment. Because the spindle have great impact in the gold processing accuracy for deformation and vibration.

The Optimization of Lapping Process Parameters Based on Extension Theory

This paper introduced Extension optimization theory into the parameters optimization of lapping process, the five process parameters of the lapping load pressure, the platen speed, the abrasive particle size, slurry flow, lapping fluid concentration are considered, the target extension decision models and integrated decision-making correlation function are established. According to the selection criteria, the optimum solution is obtained. The results showed that: as the lapping speed of 35rpm, the pressure of 11 MPa, the abrasive particle size of W7.95, the slurry flow rate of 228.75ml/min, the slurry concentration of 25%, the surface removal rate increased, the surface roughness decreases, flatness decreases.

Steam Pressure of Foaming Machine of Fuzzy PID Control and Simulation

This paper focus on designing a fuzzy PID controller design about the vapor pressure of the EPE foaming machine parameters, and raise a self-tuning method of PID parameters, and use the fuzzy control toolbox of MATLAB to simulate its control system, which are compared with the simulation of conventional PID controller, the results show the design of fuzzy PID controller have high control precision, small overshoot, good dynamic performance characteristics.

Finite Element Analysis and Structural Optimization of the Refrigerator Door Cover

Refrigerator door cover cracking as a serious hazard in many new product development. This article describes a finite element study door cover cracking BCD268 example, the use of the ABAQUS finite element analysis of the cracking mechanism. Three kinds of different options to strengthen the tendons on the numerical simulation of the BCD268 the door cover, in the simplified model were carried out finite element analysis, experimental validation, and were come to give priority to the use of the method. The cover design out the door by the production and validation, and analysis of the ABAQUS program results are consistent. This paper is succeeded in finding a way to solve the door cover cracking, and engineering experiments to prove the validity of the method.

Study of Data Fusion Method for Fault Diagnosis Based on FDR Feature Selection Algorithm and HMM/SVM Model

To effectively avoid the loss of useful information, in this paper, we extract feature information from the fault signal of rotating machinery in different aspects such as amplitude-domain, time-domain and time-frequency domain. Then for the multi-dimensional feature extraction is prone to the problem of “dimension disaster”, introduce the principles of FDR in data mining to determine the classification ability of each individual feature, and introduce the cross correlation coefficient to solve the problem that dealing with individual feature neglects the interrelationship between the features, and construct a new feature level data fusion algorithm. Finally, According to the characteristics of the HMM (Hidden Markov model), SVM (Support Vector Machine) and its hybrid model, we construct a new decision-level data fusion model.

Fault Diagnosis of Rotating Machineries and its Development Trend

This paper introduces the need for the development of fault diagnosis technology. Then the fault diagnosis procedures and principles were analyzed. The common faults of rotating machinery were classified and elaborated in detail, and presented different types of fault vibration signal amplitude-frequency diagram. Then the paper mainly described the fault diagnosis of rotating machinery commonly used method, an overview of domestic and foreign research and development, future trends and prospects of the fault diagnosis technology.