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For intermittent fault diagnosis, it is important to extract fault features. An intermittent fault feature extraction method based on wavelet transform is proposed. Firstly, the stress-intensity model is used to describe the fault process of intermittent faults, analysing the main part of intermittent fault signal characteristics. Considering the randomness and suddenness of intermittent faults, wavelet transform is used to extract intermittent fault features based on the advantages of wavelet transform in signal mutation and singularity detection. By extracting signal energy through the wavelet coefficients, intermittent fault features are obtained, which can be used to identify and isolate the intermittent faults. Finally, by a simulating circuit, transient intermittent fault response characteristics are obtained by simulation in the circuit, and the features are extracted by wavelet transform for the intermittent fault location. Results show that the intermittent fault features can be extracted by the wavelet transform, and the features can be used for intermittent fault diagnosis.

For the crack intermittency detection in circuit board, a detection method based on time domain reflectometry is proposed. And a time domain signal feature is extracted, the time domain signal feature is highly sensitive to the defect. Firstly, in order to analyze the change trend of time domain signal under intermittent disconnection. The influence of conductor crack on the physical parameters is analyzed. The physical parameters include AC/DC resistance, inductance and capacitance. And then the principle of signal reflection is described. The ringing phenomenon that caused by signal reflection is used for crack intermittency detection. Therefore the maximum, minimum and peak-peak values of time domain signal are used to detect intermittent disconnection. At last solder joint equivalent circuit is used to verify the effectiveness of the method. When the intermittent disconnection happened in circuit board, the time domain reflection phenomenon is observed clearly. The maximum, minimum and the peak-peak values of output voltage signal are changed greatly, simulation result shows that the high frequency signal is sensitive to intermittent disconnection, and the proposed method is effective.

To study the failure modes that can't be injected in the testability test, an equivalent fault selection method is presented in the paper. The principle and types of the equivalent fault in testability test are explained according to the characteristics of fault propagation. By introducing switch element in the fault-test dependency model, an equivalent fault analytical model is formed. The method was applied to select equivalent fault injection sample in testability test. The effects of fault injection between equivalent fault and original fault were compared and the method of equivalent fault selection is proved to be feasible.

Objectives A variety of studies have evaluated whether increased CRP levels have association with AF recurrence after catheter ablation. However, the results remain inconsistent. So this meta-analysis was conducted to offer suggestion. Methods Electronic databases were searched until 31st December 2012 for any CRP association studies, including PubMed, Embase, Medline, ISI Web of Knowledge and ScienceDirect. Overall and subgroup analyses were performed. Standardised mean difference (SMD) and 95% confidence interval (CI) were used to evaluate the associations between CRP levels and post-ablation AF recurrence. Statistical analysis was performed with Review Manager 5.2 and STATA11.0. Results Seven available studies were identified, which included 526 patients (179 recurrence versus 347 no recurrence). Overall, increased baseline CRP levels have significant positive association with post-ablation AF recurrence. The SMD in the CRP levels was 0.65 units (95% confidence interval 0.30 to 0.99), and the z-score for overall effect was 3.70 (p = 0.0002). The heterogeneity test showed that there were moderate differences between individual studies (p = 0.006; I 2 = 67%). Meta-regression revealed that different sample sizes of studies possibly accounted for the heterogeneity. Positive associations were also found in subgroup analyses based on sample size. When stratifying for ethnicity, similarly significant associations were found in both European (Caucasian) and Asian. Conclusions Inflammation of AF involved in electrophysiological and structural atrial remodelling and facilitated the disease development and perpetuation. Atrial specimens obtained by endomyocardial biopsy showed clusters of lymphomononuclear cells compatible with diagnosis of myocarditis in 66% of patients with lone AF, as well as, activated T lymphocytes were found in left atrial endocardium, supporting the role of local inflammation as a potential trigger of AF. CRP, an acute-phase protein produced in the liver, is a sensitive biomarker of systemic inflammation in several cardiovascular diseases. Elevated CRP levels are associated with increased risk of cardiovascular events. In the study from Narducci ML et al., atrial tissue CRP was significantly more frequent in patients with paroxysmal AF than persistent AF and there was a trend for the association between atrial tissue CRP and late recurrence of AF. The higher proportion of atrial CRP-positive specimens in paroxysmal AF than in persistent AF group may be an initial feature of myocardial damage via activation of the complement system, opsonisation, chemotaxis, and activation of inflammatory cells by this acute phase protein. Furthermore, a rise in CRP was related to left atrial size and dysfunction offered support the association between inflammation and structural remodelling.