A novel controlled attenuation parameter (CAP) has been developed for Fibroscan(®) to assess liver steatosis, simultaneously with liver stiffness measurement (LSM). We assessed CAP diagnostic accuracy in a large cohort of patients with chronic hepatitis C (CHC) virus. A total of 615 patients with CHC, who underwent both Fibroscan(®) and liver biopsy, were analysed. Fibrosis was graded using METAVIR score. Steatosis was categorized by visual assessment as S(0) : steatosis in <10% of hepatocytes, S(1) : 11-33%, S(2) : 34-66% and S(3) : 67-100%. Performances of CAP and liver stiffness were determined using receiver operating characteristic (ROC) curve analysis and cross-validated using the bootstrap method. The Obuchowski measure was used to assess overall accuracy of CAP and to differentiate between steatosis grades. In multivariate analysis, CAP was related to steatosis (P < 10(-15) ) independently of fibrosis stage (which was related to LSM). The areas under ROC curves using CAP to detect steatosis were 0.80 (95% CI, 0.75-0.84) for S ≥ S(1) , 0.86 (0.81-0.92) for S ≥ S(2) and 0.88 (0.73-1) S = S(3) . CAP exhibited a good ability to differentiate steatosis grades (Obuchowski measure = 0.92). Performance of LSM for fibrosis assessment confirmed results from previous studies. CAP is a novel tool to assess the degree of steatosis and both fibrosis and steatosis can be evaluated noninvasively during the same procedure using Fibroscan(®) , in patients with CHC.
This paper describes the use of the ExtendedPark's Vector Approach (EPVA) for diagnosing the occurrence of stator winding faults in operating three-phase synchronous and asynchronous motors. The major theoretical principles related with the EPVA are presented and it is shown how stator winding faults can be effectively diagnosed by the use of this noninvasive approach. Experimental results, obtained in the laboratory, corroborate that these faults can be detected, in the EPVA signature, by the identification of a spectral component at twice the fundamental supply frequency. On-site tests, conducted in a power generation plant and in a cement mill, demonstrate the effectiveness of the EPVA in the detection of stator circuit faults in large industrial motors, ratted up to 5 MW.
Condition monitoring and fault diagnosis are currently considered crucial means to increase the reliability and availability of wind turbines, and consequently, to reduce the wind energy cost. With similar goals, direct drive wind turbines based on permanent magnet synchronous generators (PMSGs) with full-scale power converters are an emerging and promising technology. Numerous studies show that power converters are a significant contributor to the overall failure rate of modern wind turbines. In this context, open-circuit fault diagnosis in the two power converters of a PMSG drive for wind turbine applications is addressed in this paper. A diagnostic method is proposed for each power converter, allowing real-time detection and localization of multiple open-circuit faults. The proposed methods are suitable for integration into the drive controller and to trigger remedial actions. In order to prove the reliability and effectiveness of the proposed fault diagnostic methods, several simulation and experimental results are presented.
Index Terms-Condition monitoring, fault diagnosis, multiple power switch open-circuit faults, permanent magnet machines, semiconductor device reliability, wind power generation
I. INTRODUCTIONost reduction of the generated wind energy is essential for the wind power penetration to keep increasing quickly, through more efficient, reliable and cost-effective wind turbines. Hence, the wind turbines based on PMSGs drives are a promising technology , avoiding the use of gearboxes. Furthermore, along with the PMSG, a full-scale power converter is required, which allows variable speed operation and the fulfillment of rigorous grid codes.Several issues related to wind turbines such as power quality, systems stability  and ride-through capability during grid faults  have been considered over the last few years. More recently, reliability and availability of wind Manuscript
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