The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Pamela K. Mason - One of the best experts on this subject based on the ideXlab platform.
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Cost of a recall of a single-center experience managing the Riata defibrillator lead.
American Journal of Cardiology, 2014Co-Authors: Sarah K. Hussain, Liza P. Moorman, J. Randall Moorman, John P. Dimarco, Rohit Malhotra, Andrew E. Darby, Kenneth C. Bilchick, John D. Ferguson, J. Michael Mangrum, Pamela K. MasonAbstract:Riata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, California) were recalled in 2011 due to increased risk of Insulation Failure leading to externalized cables. Fluoroscopic screening can identify Insulation Failure, although the relation between mechanical Failure and electrical Failure is unclear. At the time of the recall, the University of Virginia developed a screening program, including fluoroscopic evaluation, education sessions, device interrogation, and remote monitoring for patients with this defibrillator lead. The aim of this study was to review the outcomes of the screening program, including costs, which were absorbed by our institution. Costs were calculated using Medicare reimbursement estimates. Forty-eight patients participated in the screening program. At initial screening, 31% were found to have evidence of Insulation Failure but electrical function was normal in all leads. The cost of this program was $35,358.72. The cost per diagnosis of mechanical lead Failure was $2,357.25. During 2 years of follow-up, 1 patient experienced Riata lead electrical Failure without fluoroscopic evidence of Insulation Failure. Patients were more likely to have a lead revision if there was evidence of Insulation Failure. Lead revisions occurred at the time of generator change in 88% of patients with Insulation Failure but in only 14% of patients with a fluoroscopically normal lead (p = 0.04). The cost of recall-related defibrillator lead revisions was $81,704.55. In conclusion, our Riata screening program added expense without clear benefit to patients. In fact, patients may have been put at more risk by undergoing defibrillator lead revisions based solely on the results of the fluoroscopic screening.
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Increasing lead burden correlates with externalized cables during systematic fluoroscopic screening of Riata leads
Journal of Interventional Cardiac Electrophysiology, 2013Co-Authors: Liza P. Moorman, J. Randall Moorman, John P. Dimarco, Rohit Malhotra, Kenneth C. Bilchick, John D. Ferguson, J. Michael Mangrum, Sandeep Kamath, Andrew Darby, Pamela K. MasonAbstract:Purpose Riata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, CA, USA) have been recalled due to increased risk of Insulation Failure leading to externalized cables. As this mechanical Failure does not necessarily correlate with electrical Failure, it can be difficult to diagnose. Fluoroscopic screening can identify Insulation Failure. Studies have suggested that Insulation Failure is predominantly seen in 8-Fr, single-coil models. Our patients have exclusively dual-coil leads and a high proportion of 7-Fr leads. Methods Fluoroscopic screening was performed in 48 patients with recalled Riata leads. Twenty-three patients had 8-Fr Riata leads and 25 patients had 7-Fr Riata ST leads. Images were recorded in at least three projections and studies were reviewed by seven attending electrophysiologists. Results Externalized cables were seen in ten patients (21 %), and another five patients (10 %) had abnormal cable spacing. All device interrogations showed normal parameters. Patients with abnormal leads had more leads in situ (2.5 ± 0.7 vs. 1.6 ± 0.8 leads; P = 0.002) and a higher rate of nonischemic cardiomyopathy (80 vs. 24 %; P = 0.03). There were no differences between the groups with regards to patient age, body mass index, lead age, lead parameters, or vascular access site. There was no difference with regard to lead size ( P = 0.76). Conclusions The Riata family of leads has a high incidence of mechanical Failure, as demonstrated on fluoroscopic screening. In this study, the 7-Fr models were just as likely to mechanically fail as the 8-Fr models. Increasing lead burden and a diagnosis of nonischemic cardiomyopathy correlated with Insulation Failure.
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Increasing lead burden correlates with externalized cables during systematic fluoroscopic screening of Riata leads
Journal of Interventional Cardiac Electrophysiology, 2012Co-Authors: Liza P. Moorman, J. Randall Moorman, John P. Dimarco, Rohit Malhotra, Andrew E. Darby, Kenneth C. Bilchick, John D. Ferguson, J. Michael Mangrum, Sandeep Kamath, Pamela K. MasonAbstract:Purpose Riata and Riata ST defibrillator leads (St. Jude Medical, Sylmar, CA, USA) have been recalled due to increased risk of Insulation Failure leading to externalized cables. As this mechanical Failure does not necessarily correlate with electrical Failure, it can be difficult to diagnose. Fluoroscopic screening can identify Insulation Failure. Studies have suggested that Insulation Failure is predominantly seen in 8-Fr, single-coil models. Our patients have exclusively dual-coil leads and a high proportion of 7-Fr leads.
Minghao Fan - One of the best experts on this subject based on the ideXlab platform.
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Insulation Failure of Class 1E Cable for Nuclear Power Station Under Fire Heat Radiation
Advanced Functional Materials, 2018Co-Authors: Jiaqing Zhang, Yichen Yang, Minghao FanAbstract:In order to discover the regularity of Insulation Failure of typical cable for nuclear power plant in fire, the experimental research method was used to study the Insulation Failure of Class 1E cable for nuclear power plant under different simulated fire conditions by using cable thermal radiation test furnace in this paper. The results show that the Insulation Failure time and the breakdown time of the cable decrease exponentially with the increase of the ambient heat radiation flux, and the Insulation Failure temperature and the Insulation breakdown temperature of the cable are basically the same.
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Insulation Failure Mechanism of Cable in Fire Environment
Advanced Functional Materials, 2018Co-Authors: Jiaqing Zhang, Yichen Yang, Minghao FanAbstract:In order to reveal the Insulation Failure mechanism of the cable under the fire condition, the conductive mechanism and aging mechanism of the cable Insulation material were analyzed theoretically, and the relationship between the thermal decomposition weight loss curve and the Insulation resistance and temperature of the cable Insulation material was constructed. The results show that the reason for the Failure of the cable in the fire is that the Insulation performance of the insulating material decreases after heating. For different thermal aging degree of the cable, the decomposition process of insulating materials are divided into two stages. When the Failure occurs, the insulating material is not decomposed; when the breakdown occurs, the insulating material is in the first stage of thermal loss. Therefore, the Failure temperature of the cable can be considered mainly depends on the characteristics of its insulating material, regardless of the structure, shape and size of the cable.
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Study on Insulation Failure Time and Failure Temperature of the Aged Cables under External Heating
Procedia Engineering, 2018Co-Authors: Xie Hui, Jiaqing Zhang, Yu-fei Liu, Zhang Bosi, Wang Liufang, Minghao FanAbstract:Abstract The Insulation Failure time and Failure temperature of aged cables under external radiation heat flux were investigated experimentally in the present study. The effects of ageing type and ageing time on the Insulation Failure time and Failure temperature of cables were explored. The ozone aging, the xenon arc ageing and the high and low temperature cycle ageing of cables were considered. Results show that the Insulation Failure time decreased with the ageing time of cables under external heating. It means that the long-term used cable had serious Insulation Failure hazard. Among the three types of aged cables investigated in this study, the Insulation Failure time of xenon arc aged cables and the high and low temperature cycle aged cables were lower than the ozone aged cables. Therefore, the Insulation Failure hazard of the xenon arc aged cables and the high and low temperature cycle aged cables need more attentions.
Yang Shou-sheng - One of the best experts on this subject based on the ideXlab platform.
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Effect of protecting with conduits on Insulation Failure of ZR-VV cable
Fire Science and Technology, 2010Co-Authors: Yang Shou-shengAbstract:The Insulation Failure conditions of ZR-VV cables under different kinds of protections were studied by means of the infrared radiation reheating furnace. The test data showed that ZR-VV cable Insulation Failure temperature was little influenced by different protections and thermal environment, which probably remained at 183.5(1±10.7%) ℃. Thus, the cable Insulation Failure time was decreasing with the increase of exposure heat flux and increased when the cable was under the protection of conduit evidently, and the related variation regularity could be well fitted with exponential function model. The protective effect of fire resistant PVC conduit was much better than metal conduit when it exposed to low heat flux, but just opposite when exposed to high heat flux.
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Experiment and research on the Insulation Failure rule of the bridging polyethylene plastic cable at high temperature
Fire Science and Technology, 2009Co-Authors: Yang Shou-shengAbstract:Effects of the different high temperature and the heat aging to the bridging polyethylene Insulation cable(YJV) and the flame-retardant bridging polyethylene Insulation cable(ZR-YJV) has been studied.The 401 aged test box and the high temperature tube-type test furnace were applied.After preheating,the temperature rises to 400 ℃,450 ℃,500 ℃,550 ℃ and 600 ℃ respectively in 15 min.Results: ①The Insulation Failure temperature for definite Insulation materials is basically fixed.The time of Insulation Failure decreases as given temperature rises,and has nothing to do with environment temperature and temperature rise rate.②The Insulation Failure temperature of ZR-YJV is a little higher than that of YJV.③Effect of the heat aging to the Insulation Failure temperature of cable is evident.And the larger the aging degree is,the more evidently the Failure temperature decreases.
H. Nakamura - One of the best experts on this subject based on the ideXlab platform.
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frequency spectrum investigation and analytical diagnosis method for turn to turn short circuit Insulation Failure in stator winding of low voltage induction motor
IEEE Transactions on Dielectrics and Electrical Insulation, 2016Co-Authors: Shrinathan Esakimuthu Pandarakone, Yukio Mizuno, H. NakamuraAbstract:Low-voltage induction motors are widely used in the factories and are becoming very essential components for the industrial process. Improper diagnosis and condition monitoring of induction motor not only leads to high repair expenses but also cause extraordinary financial losses due to their unexpected downtime. In general, turn-to-turn short-circuit Failure of stator winding due to their deterioration or damage of electrical Insulation is one of the most feasible Failures in motor drive systems. This paper proposes a diagnostic method based on amplitudes of characteristic frequency components of load current as features. These features are extracted by close analysis of frequency spectrum and its dependence on load current variation. This method has the advantage of low cost and short data processing time. Also to enhance the accuracy of diagnosis, a novel diagnostic method is proposed with the aid of Support Vector Machine. It is found that the proposed diagnosis method using the features and Support Vector Machine enables the detection of a slight Insulation Failure like one turn-to-turn short-circuit with practically accepted accuracy.
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turn to turn Insulation Failure diagnosis of stator winding of low voltage induction motor with the aid of support vector machine
IEEE Transactions on Dielectrics and Electrical Insulation, 2015Co-Authors: Yusuke Yagami, Yukio Mizuno, Chika Araki, H. NakamuraAbstract:Turn-to-turn short-circuit of stator winding due to deterioration of electrical Insulation is one of the most probable faults in motor drive systems. This paper proposes two diagnostic methods to detect the fault based on Support Vector Machine. In the first method, magnitude and phase of load currents at fixed rotating speeds are considered as features reflecting winding condition. It is found that the method is effective particularly in slight Insulation Failure like one turn-to-turn short-circuit. Classification of winding condition, i.e. specification of number of short-circuit turns, is also achieved by this method. In the second method, only magnitude of load currents is treated as feature aiming at diagnosis available when load current varies. The method also has the advantage of low cost and short data processing time. It is found that two turn-to-turn short-circuit can be diagnosed with practically acceptable accuracy. An appropriate choice of the two methods should be recommended depending on the goal as well as circumstance of diagnosis.
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Probabilistic diagnosis of Insulation Failure of motor winding based on feature distributions
2012 Annual Report Conference on Electrical Insulation and Dielectric Phenomena, 2012Co-Authors: K. Kishino, Yukio Mizuno, H. NakamuraAbstract:This paper proposes a novel and simple method for diagnosing Insulation Failure (short-circuit) in stator windings of motors under load conditions. The method involves probabilistic process for gauging the probability of Failure occurrence by considering distributions of features, i.e. magnitude and phase of current flowing into stator windings, depending on the condition of the Insulation Failure of windings. A series of laboratory experiments and analyses of the results for motors with artificially introduced Insulation Failure prove that the proposed method is promising.
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Impulse testing for detection of Insulation Failure of motor winding and diagnosis based on Hidden Markov Model
IEEE Transactions on Dielectrics and Electrical Insulation, 2010Co-Authors: H. Nakamura, Masaaki Chihara, Tomokazu Inoki, Taizo Higaki, Kazuo Okuda, Yukio MizunoAbstract:Short circuit fault of a motor, due to breakdown of an insulating material of winding, is one of the most probable faults in motor drive systems. Establishment of an easy and effective fault diagnosis method has been strongly required to assure operation with high reliability. This paper proposes a novel diagnosis method for Insulation Failure of motor windings by a combination of impulse testing and pattern recognition based on Hidden Markov Model (HMM). A voltage waveform across two winding terminals is recorded under application of an impulse voltage. HMM is exploited to distinguish a small difference in voltage waveforms between healthy and faulty winding Insulations. Usefulness of the proposed diagnostic method is verified through voltage waveforms experimentally obtained for motors with several kinds of turn-to-turn Insulation Failures.
Salvador M Aceves - One of the best experts on this subject based on the ideXlab platform.
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the potential for avoiding hydrogen release from cryogenic pressure vessels after vacuum Insulation Failure
International Journal of Hydrogen Energy, 2018Co-Authors: Julio C Morenoblanco, Francisco Elizaldeblancas, A Gallegosmunoz, Salvador M AcevesAbstract:Abstract This paper presents an analysis of vacuum Insulation Failure in an automotive cryogenic pressure vessel (also known as cryo-compressed vessel) storing hydrogen. Vacuum Insulation Failure increases heat transfer into cryogenic vessels by about a factor of 100, potentially leading to rapid pressurization and venting of the cryogen to avoid exceeding maximum allowable working pressure (MAWP). Hydrogen release to the environment may be dangerous, especially if the vehicle is located in a closed space (e.g. a garage or tunnel) at the moment of Insulation Failure. We therefore consider utilization of the hydrogen in the vehicle fuel cell and dissipation of the electricity by operating vehicle accessories or electric resistances as an alternative to releasing hydrogen to the environment. We consider two strategies: initiating hydrogen extraction immediately after vacuum Insulation Failure or waiting until maximum operating pressure is reached before extraction. The results indicate that cryogenic pressure vessels have thermodynamic advantages that enable slowing down hydrogen release to moderate levels that can be consumed in the fuel cell and dissipated in vehicle accessories supplemented by electric resistances, even in the worst case when the Insulation fails at the moment when the vessel stores hydrogen near its maximum density (70 g/L at 300 bar). The two proposed strategies are therefore feasible, and the best alternative can be chosen based on economic and/or implementation constraints.