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As large proportions of power transformers are approaching or have exceeded their design life, concerns have aroused at their impact on the reliability of power networks, and forward replacement planning/budgeting is therefore required. In this paper, an appropriate transformer lifetime model is recognized as the key for the accurate replacement volume prediction. Since transformer failures are rare...
Ultrasonic technique is a well-known technique for non-destructive detection of the material defect. In this paper, we develop the ultrasonic model of Finite Element Method (FEM) for the material crack detection in a two-dimensional geometry. The FEM Model is established by the geometry of the defect and the piezoelectric transducers with the finite element analysis software ANSYS. The reflected signals...
This paper describes the challenges for the health monitoring of civil infrastructure systems and provides an overview of the state-of-the-art of currently available nondestructive evaluation (NDE) techniques based on the principle of stress wave propagation. An introduction to the health monitoring of civil infrastructures is given first. Two main categories of current NDE techniques are presented,...
The reliability of electronic systems is greatly depended on the reliability of electrical contacts inside. Gold plating is usually adopted as the top finish of the electrical contacts in dry circuits because of its excellent stability and conductibility. But driven by cost pressure, gold finish becomes thinner and thinner. It is even considered to coat gold plating only on one side of a pair of contacts...
The first critical step in system health management, which enhance the safety, reliability, and availability of the system, is collecting appropriate data for further process. In this paper, an evaluation method for monitoring nominal parameters is proposed. The approach combines classification and clustering to evaluate the relevance of the monitored parameters and the faults.
Much effort has been made to define metrics for Prognostics Health Management (PHM). The problem is that most of this effort has focused on the new concept of Prognostics performance. Attention to the importance of true Integrated Systems Health Management (ISHM) has been masked by the focus on single failure mode physics of failure. The critical metrics derived from Integrated Systems Diagnostics...
Cooling fan is commonly used in electronic system, and it is crucial for guarantying the reliability of it. In a cooling fan assembly, fan bearing failure is a major part which causes noise, vibration; reduction in rotation speed, or even locks the motor. It is necessary to conduct research on the life assessment of fan bearings. This paper presents a vibration-based fan bearing prognosis and health...
Feature dimensionality reduction is a critical task in various machine learning applications including prognostics and health management (PHM) applications. Linear transformations, most popularly principal component analysis (PCA) and linear discriminant analysis (LDA), are the most widely-used methods for feature dimensionality reduction. For classification problems, LDA, being a supervised linear...
This paper presents a method for fault diagnosis based on Mahalanobis-Taguchi system (MTS), which is applied to practical fault diagnosis for rolling element bearing. Firstly, this method utilizes time/frequency domain analysis for feature extraction from the vibration data. Then, a computational scheme based on Mahalanobis distance (MD) is used for fault clustering. In addition, Taguchi methods are...
Permutation Entropy (PE) is a new subject which talks about the scrambling and non-linearity of complex system, which has been widely studied in recent years. This paper aims to introduce the basic algorithm of PE firstly, then verify PE using simulated signal, which shows that PE is feasible for fault diagnosis. Finally, the whole life vibration data of a rolling bearing is taken as an example, comparing...
This paper presents a new application of recurrence quantification analysis (RQA) for damage severity assessment of mechanical systems. As a nonlinear time series technique, the recurrence quantification analysis derives quantitative measures from the recurrence plot (RP) to quantitatively characterize changing dynamics of a given system in the reconstructed phase space. In the present study, four...
The degradation of electrolytic capacitor is the cause of most faults of Switching-Mode Power Converters. Various tests showed that the increase of the internal Equivalent Series Resistance (ESR) of the capacitors is good indicator of their faulty state. This paper presents the equivalent model of electrolytic capacitor, analyzes several different methods of detecting the value of ESR, and proposes...
As an integral component of electronic equipments, power MOSFET with its degenerate performance affects the reliability of the whole system. The modeling of power device based on structural geometry, material properties, and boundary conditions can reduce the repetition test and shorten the failure analysis cycle. In this paper, coupled electrical-thermal-mechanical analysis based on finite element...
FPGAs are widely adopted in many application domains and the higher accuracy requirement of FPGA makes the diagnostics and prognostics techniques of FPGA-based system is becoming increasingly important. This paper takes the stuck-at fault of look-up table in programmable logic blocks as a research object and presents the diagnostic method based on the Built-in Self Test. Example is provided for the...
Methods of testability demonstration in electronic equipments are: inherent testability analysis, experimental demonstration and simulated demonstration. Each of these methods yield different aspects of the level of equipment's testability, but the result is isolated and there are no connections with each method. In order to overcome this weakness, this paper combines many aspects of testability to...
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