On the change points of mean residual life and failure rate functions for some generalized gamma type distributions

Directory of Open Access Journals (Sweden)

Parsa M.

2014-01-01

Full Text Available Mean residual life and failure rate functions are ubiquitously employed in reliability analysis. The term of useful period of lifetime distributions of bathtub-shaped failure rate functions is referred to the flat rigion of this function and has attracted authors and researchers in reliability, actuary, and survival analysis. In recent years, considering the change points of mean residual life and failure rate functions has been extensively utelized in determining the optimum burn-in time. In this paper we investigate the difference between the change points of failure rate and mean residual life functions of some generalized gamma type distributions due to the capability of these distributions in modeling various bathtub-shaped failure rate functions.

Development of component failure data for seismic risk analysis

International Nuclear Information System (INIS)

Fray, R.R.; Moulia, T.A.

1981-01-01

This paper describes the quantification and utilization of seismic failure data used in the Diablo Canyon Seismic Risk Study. A single variable representation of earthquake severity that uses peak horizontal ground acceleration to characterize earthquake severity was employed. The use of a multiple variable representation would allow direct consideration of vertical accelerations and the spectral nature of earthquakes but would have added such complexity that the study would not have been feasible. Vertical accelerations and spectral nature were indirectly considered because component failure data were derived from design analyses, qualification tests and engineering judgment that did include such considerations. Two types of functions were used to describe component failure probabilities. Ramp functions were used for components, such as piping and structures, qualified by stress analysis. 'Anchor points' for ramp functions were selected by assuming a zero probability of failure at code allowable stress levels and unity probability of failure at ultimate stress levels. The accelerations corresponding to allowable and ultimate stress levels were determined by conservatively assuming a linear relationship between seismic stress and ground acceleration. Step functions were used for components, such as mechanical and electrical equipment, qualified by testing. Anchor points for step functions were selected by assuming a unity probability of failure above the qualification acceleration. (orig./HP)

Analysis of calculating methods for failure distribution function based on maximal entropy principle

International Nuclear Information System (INIS)

Guo Chunying; Lin Yuangen; Jiang Meng; Wu Changli

2009-01-01

The computation of invalidation distribution functions of electronic devices when exposed in gamma rays is discussed here. First, the possible devices failure distribution models are determined through the tests of statistical hypotheses using the test data. The results show that: the devices' failure distribution can obey multi-distributions when the test data is few. In order to decide the optimum failure distribution model, the maximal entropy principle is used and the elementary failure models are determined. Then, the Bootstrap estimation method is used to simulate the intervals estimation of the mean and the standard deviation. On the basis of this, the maximal entropy principle is used again and the simulated annealing method is applied to find the optimum values of the mean and the standard deviation. Accordingly, the electronic devices' optimum failure distributions are finally determined and the survival probabilities are calculated. (authors)

Reliability Evaluation of Machine Center Components Based on Cascading Failure Analysis

Science.gov (United States)

Zhang, Ying-Zhi; Liu, Jin-Tong; Shen, Gui-Xiang; Long, Zhe; Sun, Shu-Guang

2017-07-01

In order to rectify the problems that the component reliability model exhibits deviation, and the evaluation result is low due to the overlook of failure propagation in traditional reliability evaluation of machine center components, a new reliability evaluation method based on cascading failure analysis and the failure influenced degree assessment is proposed. A direct graph model of cascading failure among components is established according to cascading failure mechanism analysis and graph theory. The failure influenced degrees of the system components are assessed by the adjacency matrix and its transposition, combined with the Pagerank algorithm. Based on the comprehensive failure probability function and total probability formula, the inherent failure probability function is determined to realize the reliability evaluation of the system components. Finally, the method is applied to a machine center, it shows the following: 1) The reliability evaluation values of the proposed method are at least 2.5% higher than those of the traditional method; 2) The difference between the comprehensive and inherent reliability of the system component presents a positive correlation with the failure influenced degree of the system component, which provides a theoretical basis for reliability allocation of machine center system.

Worsening renal function in heart failure: the need for a consensus definition.

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Sheerin, Noella J; Newton, Phillip J; Macdonald, Peter S; Leung, Dominic Y C; Sibbritt, David; Spicer, Stephen Timothy; Johnson, Kay; Krum, Henry; Davidson, Patricia M

2014-07-01

Acute decompensated heart failure is a common cause of hospitalisation. This is a period of vulnerability both in altered pathophysiology and also the potential for iatrogenesis due to therapeutic interventions. Renal dysfunction is often associated with heart failure and portends adverse outcomes. Identifying heart failure patients at risk of renal dysfunction is important in preventing progression to chronic kidney disease or worsening renal function, informing adjustment to medication management and potentially preventing adverse events. However, there is no working or consensus definition in international heart failure management guidelines for worsening renal function. In addition, there appears to be no concordance or adaptation of chronic kidney disease guidelines by heart failure guideline development groups for the monitoring of chronic kidney disease in heart failure. Our aim is to encourage the debate for an agreed definition given the prognostic impact of worsening renal function in heart failure. We present the case for the uptake of the Acute Kidney Injury Network criteria for acute kidney injury with some minor alterations. This has the potential to inform study design and meta-analysis thereby building the knowledgebase for guideline development. Definition consensus supports data element, clinical registry and electronic algorithm innovation as instruments for quality improvement and clinical research for better patient outcomes. In addition, we recommend all community managed heart failure patients have their baseline renal function classified and routinely monitored in accordance with established renal guidelines to help identify those at increased risk for worsening renal function or progression to chronic kidney disease. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Failures and Inabilities of High School Students about Quadratic Equations and Functions

Science.gov (United States)

Memnun, Dilek Sezgin; Aydin, Bünyamin; Dinç, Emre; Çoban, Merve; Sevindik, Fatma

2015-01-01

In this research study, it was aimed to examine failures and inabilities of eleventh grade students about quadratic equations and functions. For this purpose, these students were asked ten open-ended questions. The analysis of the answers given by the students to these questions indicated that a significant part of these students had failures and…

Renal function assessment in heart failure.

Science.gov (United States)

Pérez Calvo, J I; Josa Laorden, C; Giménez López, I

Renal function is one of the most consistent prognostic determinants in heart failure. The prognostic information it provides is independent of the ejection fraction and functional status. This article reviews the various renal function assessment measures, with special emphasis on the fact that the patient's clinical situation and response to the heart failure treatment should be considered for the correct interpretation of the results. Finally, we review the literature on the performance of tubular damage biomarkers. Copyright © 2017 Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI). All rights reserved.

Probabilistic analysis on the failure of reactivity control for the PWR

Science.gov (United States)

Sony Tjahyani, D. T.; Deswandri; Sunaryo, G. R.

2018-02-01

The fundamental safety function of the power reactor is to control reactivity, to remove heat from the reactor, and to confine radioactive material. The safety analysis is used to ensure that each parameter is fulfilled during the design and is done by deterministic and probabilistic method. The analysis of reactivity control is important to be done because it will affect the other of fundamental safety functions. The purpose of this research is to determine the failure probability of the reactivity control and its failure contribution on a PWR design. The analysis is carried out by determining intermediate events, which cause the failure of reactivity control. Furthermore, the basic event is determined by deductive method using the fault tree analysis. The AP1000 is used as the object of research. The probability data of component failure or human error, which is used in the analysis, is collected from IAEA, Westinghouse, NRC and other published documents. The results show that there are six intermediate events, which can cause the failure of the reactivity control. These intermediate events are uncontrolled rod bank withdrawal at low power or full power, malfunction of boron dilution, misalignment of control rod withdrawal, malfunction of improper position of fuel assembly and ejection of control rod. The failure probability of reactivity control is 1.49E-03 per year. The causes of failures which are affected by human factor are boron dilution, misalignment of control rod withdrawal and malfunction of improper position for fuel assembly. Based on the assessment, it is concluded that the failure probability of reactivity control on the PWR is still within the IAEA criteria.

Predicting kidney graft failure using time-dependent renal function covariates

NARCIS (Netherlands)

de Bruijne, Mattheus H. J.; Sijpkens, Yvo W. J.; Paul, Leendert C.; Westendorp, Rudi G. J.; van Houwelingen, Hans C.; Zwinderman, Aeilko H.

2003-01-01

Chronic rejection and recurrent disease are the major causes of late graft failure in renal transplantation. To assess outcome, most researchers use Cox proportional hazard analysis with time-fixed covariates. We developed a model adding time-dependent renal function covariates to improve the

On changing points of mean residual life and failure rate function for some generalized Weibull distributions

International Nuclear Information System (INIS)

Xie, M.; Goh, T.N.; Tang, Y.

2004-01-01

The failure rate function and mean residual life function are two important characteristics in reliability analysis. Although many papers have studied distributions with bathtub-shaped failure rate and their properties, few have focused on the underlying associations between the mean residual life and failure rate function of these distributions, especially with respect to their changing points. It is known that the change point for mean residual life can be much earlier than that of failure rate function. In fact, the failure rate function should be flat for a long period of time for a distribution to be useful in practice. When the difference between the change points is large, the flat portion tends to be longer. This paper investigates the change points and focuses on the difference of the changing points. The exponentiated Weibull, a modified Weibull, and an extended Weibull distribution, all with bathtub-shaped failure rate function will be used. Some other issues related to the flatness of the bathtub curve are discussed

BACFIRE, Minimal Cut Sets Common Cause Failure Fault Tree Analysis

International Nuclear Information System (INIS)

Fussell, J.B.

1983-01-01

1 - Description of problem or function: BACFIRE, designed to aid in common cause failure analysis, searches among the basic events of a minimal cut set of the system logic model for common potential causes of failure. The potential cause of failure is called a qualitative failure characteristics. The algorithm searches qualitative failure characteristics (that are part of the program input) of the basic events contained in a set to find those characteristics common to all basic events. This search is repeated for all cut sets input to the program. Common cause failure analysis is thereby performed without inclusion of secondary failure in the system logic model. By using BACFIRE, a common cause failure analysis can be added to an existing system safety and reliability analysis. 2 - Method of solution: BACFIRE searches the qualitative failure characteristics of the basic events contained in the fault tree minimal cut set to find those characteristics common to all basic events by either of two criteria. The first criterion can be met if all the basic events in a minimal cut set are associated by a condition which alone may increase the probability of multiple component malfunction. The second criterion is met if all the basic events in a minimal cut set are susceptible to the same secondary failure cause and are located in the same domain for that cause of secondary failure. 3 - Restrictions on the complexity of the problem - Maxima of: 1001 secondary failure maps, 101 basic events, 10 cut sets

The analysis of failure data in the presence of critical and degraded failures

International Nuclear Information System (INIS)

Haugen, Knut; Hokstad, Per; Sandtorv, Helge

1997-01-01

Reported failures are often classified into severityclasses, e.g., as critical or degraded. The critical failures correspond to loss of function(s) and are those of main concern. The rate of critical failures is usually estimated by the number of observed critical failures divided by the exposure time, thus ignoring the observed degraded failures. In the present paper failure data are analyzed, applying an alternative estimate for the critical failure rate, also taking the number of observed degraded failures into account. The model includes two alternative failure mechanisms, one being of the shock type, immediately leading to a critical failure, another resulting in a gradual deterioration, leading to a degraded failure before the critical failure occurs. Failure data on safety valves from the OREDA (Offshore REliability DAta) data base are analyzed using this model. The estimate for the critical failure rate is obtained and compared with the standard estimate

Failure analysis: Status and future trends

International Nuclear Information System (INIS)

Anderson, R.E.; Soden, J.M.; Henderson, C.L.

1995-01-01

Failure analysis is a critical element in the integrated circuit manufacturing industry. This paper reviews the changing role of failure analysis and describes major techniques employed in the industry today. Several advanced failure analysis techniques that meet the challenges imposed by advancements in integrated circuit technology are described and their applications are discussed. Future trends in failure analysis needed to keep pace with the continuing advancements in integrated circuit technology are anticipated

Failure analysis of vise jaw holders for hacksaw machine

Directory of Open Access Journals (Sweden)

Essam Ali Al-Bahkali

2018-01-01

Full Text Available Failure analysis in mechanical components has been investigated in many studies in the last few years. Failure analysis and prevention are important functions in all engineering disciplines. Materials engineers are often the lead role in the analysis of failures, where a component or product fails in service or if a failure occurs during manufacturing or production processing. In any case, one must determine the cause of the failure to prevent future occurrences and/or to improve the performance of the device, component or structure. For example, the vise jaw holders of hacksaws can break due to accidental heavy loads or machine misuse. The parts that break are the stationary and movable vise jaw holders and the connecter power screw between the holders. To investigate the failure of these components, a three-dimensional finite element model for stress analysis was performed. First, the analysis identified the broken components of the hacksaw machine. In addition, the type of materials of the broken parts was identified, a CAD model was built, and the hacksaw mechanism was analyzed to determine the accurate applied loads on the broken parts. After analyzing the model using Abaqus CAE software, the results showed that the location of the high stresses was identical with the high-stress locations in the original, broken parts. Furthermore, the power screw was subjected to a high load, which deformed the power screw. Also, the stationary vise jaw holder was broken by impact because it was not touched by the power screw until the movable vise jaw holder broke. A conclusion is drawn from the failure analysis and a way to improve the design of the broken parts is suggested.

Analysis Method of Common Cause Failure on Non-safety Digital Control System

Energy Technology Data Exchange (ETDEWEB)

Kim, Yun Goo; Oh, Eun Gse [KHNP, Daejeon (Korea, Republic of)

2014-08-15

The effects of common cause failure on safety digital instrumentation and control system had been considered in defense in depth analysis with safety analysis method. However, the effects of common cause failure on non-safety digital instrumentation and control system also should be evaluated. The common cause failure can be included in credible failure on the non-safety system. In the I and C architecture of nuclear power plant, many design feature has been applied for the functional integrity of control system. One of that is segmentation. Segmentation defenses the propagation of faults in the I and C architecture. Some of effects from common cause failure also can be limited by segmentation. Therefore, in this paper there are two type of failure mode, one is failures in one control group which is segmented, and the other is failures in multiple control group because that the segmentation cannot defense all effects from common cause failure. For each type, the worst failure scenario is needed to be determined, so the analysis method has been proposed in this paper. The evaluation can be qualitative when there is sufficient justification that the effects are bounded in previous safety analysis. When it is not bounded in previous safety analysis, additional analysis should be done with conservative assumptions method of previous safety analysis or best estimation method with realistic assumptions.

Reliability analysis of multi-trigger binary systems subject to competing failures

International Nuclear Information System (INIS)

Wang, Chaonan; Xing, Liudong; Levitin, Gregory

2013-01-01

This paper suggests two combinatorial algorithms for the reliability analysis of multi-trigger binary systems subject to competing failure propagation and failure isolation effects. Propagated failure with global effect (PFGE) is referred to as a failure that not only causes outage to the component from which the failure originates, but also propagates through all other system components causing the entire system failure. However, the propagation effect from the PFGE can be isolated in systems with functional dependence (FDEP) behavior. This paper studies two distinct consequences of PFGE resulting from a competition in the time domain between the failure isolation and failure propagation effects. As compared to existing works on competing failures that are limited to systems with a single FDEP group, this paper considers more complicated cases where the systems have multiple dependent FDEP groups. Analysis of such systems is more challenging because both the occurrence order between the trigger failure event and PFGE from the dependent components and the occurrence order among the multiple trigger failure events have to be considered. Two combinatorial and analytical algorithms are proposed. Both of them have no limitation on the type of time-to-failure distributions for the system components. Their correctness is verified using a Markov-based method. An example of memory systems is analyzed to demonstrate and compare the applications and advantages of the two proposed algorithms. - Highlights: ► Reliability of binary systems with multiple dependent functional dependence groups is analyzed. ► Competing failure propagation and failure isolation effect is considered. ► The proposed algorithms are combinatorial and applicable to any arbitrary type of time-to-failure distributions for system components.

Common Cause Failure Analysis for the Digital Plant Protection System

International Nuclear Information System (INIS)

Kagn, Hyun Gook; Jang, Seung Cheol

2005-01-01

Safety-critical systems such as nuclear power plants adopt the multiple-redundancy design in order to reduce the risk from the single component failure. The digitalized safety-signal generation system is also designed based on the multiple-redundancy strategy which consists of more redundant components. The level of the redundant design of digital systems is usually higher than those of conventional mechanical systems. This higher redundancy would clearly reduce the risk from the single failure of components, but raise the importance of the common cause failure (CCF) analysis. This research aims to develop the practical and realistic method for modeling the CCF in digital safety-critical systems. We propose a simple and practical framework for assessing the CCF probability of digital equipment. Higher level of redundancy causes the difficulty of CCF analysis because it results in impractically large number of CCF events in the fault tree model when we use conventional CCF modeling methods. We apply the simplified alpha-factor (SAF) method to the digital system CCF analysis. The precedent study has shown that SAF method is quite realistic but simple when we consider carefully system success criteria. The first step for using the SAF method is the analysis of target system for determining the function failure cases. That is, the success criteria of the system could be derived from the target system's function and configuration. Based on this analysis, we can calculate the probability of single CCF event which represents the CCF events resulting in the system failure. In addition to the application of SAF method, in order to accommodate the other characteristics of digital technology, we develop a simple concept and several equations for practical use

Sleep Disturbance, Daytime Symptoms, and Functional Performance in Patients With Stable Heart Failure: A Mediation Analysis.

Science.gov (United States)

Jeon, Sangchoon; Redeker, Nancy S

2016-01-01

Sleep disturbance is common among patients with heart failure (HF) who also experience symptom burden and poor functional performance. We evaluated the extent to which sleep-related, daytime symptoms (fatigue, excessive daytime sleepiness, and depressive symptoms) mediate the relationship between sleep disturbance and functional performance among patients with stable HF. We recruited patients with stable HF for this secondary analysis of data from a cross-sectional, observational study. Participants completed unattended ambulatory polysomnography from which the Respiratory Disturbance Index was calculated, along with a Six-Minute Walk Test, questionnaires to elicit sleep disturbance (Pittsburgh Sleep Quality Index, Insomnia Symptoms from the Sleep Habits Questionnaire), daytime symptoms (Center for Epidemiologic Studies Depression Scale, Global Fatigue Index, Epworth Sleepiness Scale), and self-reported functional performance (Medical Outcomes Study SF36 V2 Physical Function Scale). We used structural equation modeling with latent variables for the key analysis. Follow-up, exploratory regression analysis with bootstrapped samples was used to examine the extent to which individual daytime symptoms mediated effects of sleep disturbance on functional performance after controlling for clinical and demographic covariates. The sample included 173 New York Heart Association Class I-IV HF patients (n = 60/34.7% women; M = 60.7, SD = 16.07 years of age). Daytime symptoms mediated the relationship between sleep disturbance and functional performance. Fatigue and depression mediated the relationship between insomnia symptoms and self-reported functional performance, whereas fatigue and sleepiness mediated the relationship between sleep quality and functional performance. Sleepiness mediated the relationship between the respiratory index and self-reported functional performance only in people who did not report insomnia. Daytime symptoms explain the relationships between sleep

Common cause failure analysis methodology for complex systems

International Nuclear Information System (INIS)

Wagner, D.P.; Cate, C.L.; Fussell, J.B.

1977-01-01

Common cause failure analysis, also called common mode failure analysis, is an integral part of a complex system reliability analysis. This paper extends existing methods of computer aided common cause failure analysis by allowing analysis of the complex systems often encountered in practice. The methods presented here aid in identifying potential common cause failures and also address quantitative common cause failure analysis

A statistical analysis of pellet-clad interaction failures in water reactor fuel

International Nuclear Information System (INIS)

McDonald, S.G.; Fardo, R.D.; Sipush, P.J.; Kaiser, R.S.

1981-01-01

The primary objective of the statistical analysis was to develop a mathematical function that would predict PCI fuel rod failures as a function of the imposed operating conditions. Linear discriminant analysis of data from both test and commercial reactors was performed. The initial data base used encompassed 713 data points (117 failures and 596 non-failures) representing a wide variety of water cooled reactor fuel (PWR, BWR, CANDU, and SGHWR). When applied on a best-estimate basis, the resulting function simultaneously predicts approximately 80 percent of both the failure and non-failure data correctly. One of the most significant predictions of the analysis is that relatively large changes in power can be tolerated when the pre-ramp irradiation power is low, but that only small changes in power can be tolerated when the pre-ramp irradiation power is high. However, it is also predicted that fuel rods irradiated at low power will fail at lower final powers than those irradiated at high powers. Other results of the analysis are that fuel rods with high clad operating temperatures can withstand larger power increases that fuel rods with low clad operating temperatures, and that burnup has only a minimal effect on PCI performance after levels of approximately 10000 MWD/MTU have been exceeded. These trends in PCI performance and the operating parameters selected are believed to be consistent with mechanistic considerations. Published PCI data indicate that BWR fuel usually operates at higher local powers and changes in power, lower clad temperatures, and higher local ramp rates than PWR fuel

Failure modes and effects analysis of fusion magnet systems

International Nuclear Information System (INIS)

Zimmermann, M.; Kazimi, M.S.; Siu, N.O.; Thome, R.J.

1988-12-01

A failure modes and consequence analysis of fusion magnet system is an important contributor towards enhancing the design by improving the reliability and reducing the risk associated with the operation of magnet systems. In the first part of this study, a failure mode analysis of a superconducting magnet system is performed. Building on the functional breakdown and the fault tree analysis of the Toroidal Field (TF) coils of the Next European Torus (NET), several subsystem levels are added and an overview of potential sources of failures in a magnet system is provided. The failure analysis is extended to the Poloidal Field (PF) magnet system. Furthermore, an extensive analysis of interactions within the fusion device caused by the operation of the PF magnets is presented in the form of an Interaction Matrix. A number of these interactions may have significant consequences for the TF magnet system particularly interactions triggered by electrical failures in the PF magnet system. In the second part of this study, two basic categories of electrical failures in the PF magnet system are examined: short circuits between the terminals of external PF coils, and faults with a constant voltage applied at external PF coil terminals. An electromagnetic model of the Compact Ignition Tokamak (CIT) is used to examine the mechanical load conditions for the PF and the TF coils resulting from these fault scenarios. It is found that shorts do not pose large threats to the PF coils. Also, the type of plasma disruption has little impact on the net forces on the PF and the TF coils. 39 refs., 30 figs., 12 tabs

Estimation of functional failure probability of passive systems based on adaptive importance sampling method

International Nuclear Information System (INIS)

Wang Baosheng; Wang Dongqing; Zhang Jianmin; Jiang Jing

2012-01-01

In order to estimate the functional failure probability of passive systems, an innovative adaptive importance sampling methodology is presented. In the proposed methodology, information of variables is extracted with some pre-sampling of points in the failure region. An important sampling density is then constructed from the sample distribution in the failure region. Taking the AP1000 passive residual heat removal system as an example, the uncertainties related to the model of a passive system and the numerical values of its input parameters are considered in this paper. And then the probability of functional failure is estimated with the combination of the response surface method and adaptive importance sampling method. The numerical results demonstrate the high computed efficiency and excellent computed accuracy of the methodology compared with traditional probability analysis methods. (authors)

Isogeometric failure analysis

NARCIS (Netherlands)

Verhoosel, C.V.; Scott, M.A.; Borden, M.J.; Borst, de R.; Hughes, T.J.R.; Mueller-Hoeppe, D.; Loehnert, S.; Reese, S.

2011-01-01

Isogeometric analysis is a versatile tool for failure analysis. On the one hand, the excellent control over the inter-element continuity conditions enables a natural incorporation of continuum constitutive relations that incorporate higher-order strain gradients, as in gradient plasticity or damage.

Failure Analysis

International Nuclear Information System (INIS)

Iorio, A.F.; Crespi, J.C.

1987-01-01

After ten years of operation at the Atucha I Nuclear Power Station a gear belonging to a pressurized heavy water reactor refuelling machine, failed. The gear box was used to operate the inlet-outlet heavy-water valve of the machine. Visual examination of the gear device showed an absence of lubricant and that several gear teeth were broken at the root. Motion was transmitted with a speed-reducing device with controlled adjustable times in order to produce a proper fitness of the valve closure. The aim of this paper is to discuss the results of the gear failure analysis in order to recommend the proper solution to prevent further failures. (Author)

Prediction of hospital failure: a post-PPS analysis.

Science.gov (United States)

Gardiner, L R; Oswald, S L; Jahera, J S

1996-01-01

This study investigates the ability of discriminant analysis to provide accurate predictions of hospital failure. Using data from the period following the introduction of the Prospective Payment System, we developed discriminant functions for each of two hospital ownership categories: not-for-profit and proprietary. The resulting discriminant models contain six and seven variables, respectively. For each ownership category, the variables represent four major aspects of financial health (liquidity, leverage, profitability, and efficiency) plus county marketshare and length of stay. The proportion of closed hospitals misclassified as open one year before closure does not exceed 0.05 for either ownership type. Our results show that discriminant functions based on a small set of financial and nonfinancial variables provide the capability to predict hospital failure reliably for both not-for-profit and proprietary hospitals.

Left atrial function in heart failure with impaired and preserved ejection fraction.

Science.gov (United States)

Fang, Fang; Lee, Alex Pui-Wai; Yu, Cheuk-Man

2014-09-01

Left atrial structural and functional changes in heart failure are relatively ignored parts of cardiac assessment. This review illustrates the pathophysiological and functional changes in left atrium in heart failure as well as their prognostic value. Heart failure can be divided into those with systolic dysfunction and heart failure with preserved ejection fraction (HFPEF). Left atrial enlargement and dysfunction commonly occur in systolic heart failure, in particular, in idiopathic dilated cardiomyopathy. Atrial enlargement and dysfunction also carry important prognostic value in systolic heart failure, independently of known parameters such as left ventricular ejection fraction. In HFPEF, there is evidence of left atrial enlargement, impaired atrial compliance, and reduction of atrial pump function. This occurs not only at rest but also during exercise, indicating significant impairment of atrial contractile reserve. Furthermore, atrial dyssynchrony is common in HFPEF. These factors further contribute to the development of new onset or progression of atrial arrhythmias, in particular, atrial fibrillation. Left atrial function is an integral part of cardiac function and its structural and functional changes in heart failure are common. As changes of left atrial structure and function have different clinical implications in systolic heart failure and HFPEF, routine assessment is warranted.

Failure Modes and Effects Analysis (FMEA) Assistant Tool Feasibility Study

Science.gov (United States)

Flores, Melissa D.; Malin, Jane T.; Fleming, Land D.

2013-09-01

An effort to determine the feasibility of a software tool to assist in Failure Modes and Effects Analysis (FMEA) has been completed. This new and unique approach to FMEA uses model based systems engineering concepts to recommend failure modes, causes, and effects to the user after they have made several selections from pick lists about a component's functions and inputs/outputs. Recommendations are made based on a library using common failure modes identified over the course of several major human spaceflight programs. However, the tool could be adapted for use in a wide range of applications from NASA to the energy industry.

Failure Modes and Effects Analysis (FMEA) Assistant Tool Feasibility Study

Science.gov (United States)

Flores, Melissa; Malin, Jane T.

2013-01-01

An effort to determine the feasibility of a software tool to assist in Failure Modes and Effects Analysis (FMEA) has been completed. This new and unique approach to FMEA uses model based systems engineering concepts to recommend failure modes, causes, and effects to the user after they have made several selections from pick lists about a component s functions and inputs/outputs. Recommendations are made based on a library using common failure modes identified over the course of several major human spaceflight programs. However, the tool could be adapted for use in a wide range of applications from NASA to the energy industry.

The function and failure of sensory predictions.

Science.gov (United States)

Bansal, Sonia; Ford, Judith M; Spering, Miriam

2018-04-23

Humans and other primates are equipped with neural mechanisms that allow them to automatically make predictions about future events, facilitating processing of expected sensations and actions. Prediction-driven control and monitoring of perceptual and motor acts are vital to normal cognitive functioning. This review provides an overview of corollary discharge mechanisms involved in predictions across sensory modalities and discusses consequences of predictive coding for cognition and behavior. Converging evidence now links impairments in corollary discharge mechanisms to neuropsychiatric symptoms such as hallucinations and delusions. We review studies supporting a prediction-failure hypothesis of perceptual and cognitive disturbances. We also outline neural correlates underlying prediction function and failure, highlighting similarities across the visual, auditory, and somatosensory systems. In linking basic psychophysical and psychophysiological evidence of visual, auditory, and somatosensory prediction failures to neuropsychiatric symptoms, our review furthers our understanding of disease mechanisms. © 2018 New York Academy of Sciences.

The interaction of NDE and failure analysis

International Nuclear Information System (INIS)

Nichols, R.W.

1988-01-01

This paper deals with the use of Non-Destructive Examination (NDE) and failure analysis for the assessment of the structural integrity. It appears that failure analysis enables to know whether NDE is required or not, and can help to direct NDE into the most useful directions by identifying the areas where it is most important that defects are absent. It also appears that failure analysis can help the operator to decide which NDE method is best suited to the component studied and provides detailed specifications for this NDE method. The interaction between failure analysis and NDE is then described. (TEC)

The interaction of NDE and failure analysis

Energy Technology Data Exchange (ETDEWEB)

Nichols, R W

1988-12-31

This paper deals with the use of Non-Destructive Examination (NDE) and failure analysis for the assessment of the structural integrity. It appears that failure analysis enables to know whether NDE is required or not, and can help to direct NDE into the most useful directions by identifying the areas where it is most important that defects are absent. It also appears that failure analysis can help the operator to decide which NDE method is best suited to the component studied and provides detailed specifications for this NDE method. The interaction between failure analysis and NDE is then described. (TEC).

Bayesian Analysis of the Survival Function and Failure Rate of Weibull Distribution with Censored Data

Directory of Open Access Journals (Sweden)

Chris Bambey Guure

2012-01-01

Full Text Available The survival function of the Weibull distribution determines the probability that a unit or an individual will survive beyond a certain specified time while the failure rate is the rate at which a randomly selected individual known to be alive at time will die at time (. The classical approach for estimating the survival function and the failure rate is the maximum likelihood method. In this study, we strive to determine the best method, by comparing the classical maximum likelihood against the Bayesian estimators using an informative prior and a proposed data-dependent prior known as generalised noninformative prior. The Bayesian estimation is considered under three loss functions. Due to the complexity in dealing with the integrals using the Bayesian estimator, Lindley’s approximation procedure is employed to reduce the ratio of the integrals. For the purpose of comparison, the mean squared error (MSE and the absolute bias are obtained. This study is conducted via simulation by utilising different sample sizes. We observed from the study that the generalised prior we assumed performed better than the others under linear exponential loss function with respect to MSE and under general entropy loss function with respect to absolute bias.

Adaptive Failure Identification for Healthcare Risk Analysis and Its Application on E-Healthcare

Directory of Open Access Journals (Sweden)

Kuo-Chung Chu

2014-01-01

Full Text Available To satisfy the requirement for diverse risk preferences, we propose a generic risk priority number (GRPN function that assigns a risk weight to each parameter such that they represent individual organization/department/process preferences for the parameters. This research applies GRPN function-based model to differentiate the types of risk, and primary data are generated through simulation. We also conduct sensitivity analysis on correlation and regression to compare it with the traditional RPN (TRPN. The proposed model outperforms the TRPN model and provides a practical, effective, and adaptive method for risk evaluation. In particular, the defined GRPN function offers a new method to prioritize failure modes in failure mode and effect analysis (FMEA. The different risk preferences considered in the healthcare example show that the modified FMEA model can take into account the various risk factors and prioritize failure modes more accurately. In addition, the model also can apply to a generic e-healthcare service environment with a hierarchical architecture.

PACC information management code for common cause failures analysis

International Nuclear Information System (INIS)

Ortega Prieto, P.; Garcia Gay, J.; Mira McWilliams, J.

1987-01-01

The purpose of this paper is to present the PACC code, which, through an adequate data management, makes the task of computerized common-mode failure analysis easier. PACC processes and generates information in order to carry out the corresponding qualitative analysis, by means of the boolean technique of transformation of variables, and the quantitative analysis either using one of several parametric methods or a direct data-base. As far as the qualitative analysis is concerned, the code creates several functional forms for the transformation equations according to the user's choice. These equations are subsequently processed by boolean manipulation codes, such as SETS. The quantitative calculations of the code can be carried out in two different ways: either starting from a common cause data-base, or through parametric methods, such as the Binomial Failure Rate Method, the Basic Parameters Method or the Multiple Greek Letter Method, among others. (orig.)

Analysis approach for common cause failure on non-safety digital control system

Energy Technology Data Exchange (ETDEWEB)

Kim, Yun Goo; Oh, Eungse [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

2014-05-15

The effects of common cause failure (CCF) on safety digital instrumentation and control (I and C) system had been considered in defense in depth and diversity coping analysis with safety analysis method. For the non-safety system, single failure had been considered for safety analysis. IEEE Std. 603-1991, Clause 5.6.3.1(2), 'Isolation' states that no credible failure on the non-safety side of an isolation device shall prevent any portion of a safety system from meeting its minimum performance requirements during and following any design basis event requiring that safety function. The software CCF is one of the credible failure on the non-safety side. In advanced digital I and C system, same hardware component is used for different control system and the defect in manufacture or common external event can generate CCF. Moreover, the non-safety I and C system uses complex software for its various function and software quality assurance for the development process is less severe than safety software for the cost effective design. Therefore the potential defects in software cannot be ignored and the effect of software CCF on non-safety I and C system is needed to be evaluated. This paper proposes the general process and considerations for the analysis of CCF on non-safety I and C system.

FRAC (failure rate analysis code): a computer program for analysis of variance of failure rates. An application user's guide

International Nuclear Information System (INIS)

Martz, H.F.; Beckman, R.J.; McInteer, C.R.

1982-03-01

Probabilistic risk assessments (PRAs) require estimates of the failure rates of various components whose failure modes appear in the event and fault trees used to quantify accident sequences. Several reliability data bases have been designed for use in providing the necessary reliability data to be used in constructing these estimates. In the nuclear industry, the Nuclear Plant Reliability Data System (NPRDS) and the In-Plant Reliability Data System (IRPDS), among others, were designed for this purpose. An important characteristic of such data bases is the selection and identification of numerous factors used to classify each component that is reported and the subsequent failures of each component. However, the presence of such factors often complicates the analysis of reliability data in the sense that it is inappropriate to group (that is, pool) data for those combinations of factors that yield significantly different failure rate values. These types of data can be analyzed by analysis of variance. FRAC (Failure Rate Analysis Code) is a computer code that performs an analysis of variance of failure rates. In addition, FRAC provides failure rate estimates

Failure mode, effect and criticality analysis (FMECA) on mechanical subsystems of diesel generator at NPP

International Nuclear Information System (INIS)

Kim, Tae Woon; Singh, Brijendra; Sung, Tae Yong; Park, Jin Hee; Lee, Yoon Hwan

1996-06-01

Largely, the RCM approach can be divided in three phases; (1) Functional failure analysis (FFA) on the selected system or subsystem, (2) Failure mode, effect and criticality analysis (FMECA) to identify the impact of failure to plant safety or economics, (3) Logical tree analysis (LTA) to select appropriate preventive maintenance and surveillance tasks. This report presents FMECA results for six mechanical subsystems of the diesel generators of nuclear power plants. The six mechanical subsystems are Starting air, Lub oil, Governor, Jacket water cooling, Fuel, and Engine subsystems. Generic and plant-specific failure and maintenance records are reviewed to identify critical components/failure modes. FMECA was performed for these critical component/failure modes. After reviewing current preventive maintenance activities of Wolsung unit 1, draft RCM recommendations are developed. 6 tabs., 16 refs. (Author)

Failure mode, effect and criticality analysis (FMECA) on mechanical subsystems of diesel generator at NPP

Energy Technology Data Exchange (ETDEWEB)

Kim, Tae Woon; Singh, Brijendra; Sung, Tae Yong; Park, Jin Hee; Lee, Yoon Hwan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1996-06-01

Largely, the RCM approach can be divided in three phases; (1) Functional failure analysis (FFA) on the selected system or subsystem, (2) Failure mode, effect and criticality analysis (FMECA) to identify the impact of failure to plant safety or economics, (3) Logical tree analysis (LTA) to select appropriate preventive maintenance and surveillance tasks. This report presents FMECA results for six mechanical subsystems of the diesel generators of nuclear power plants. The six mechanical subsystems are Starting air, Lub oil, Governor, Jacket water cooling, Fuel, and Engine subsystems. Generic and plant-specific failure and maintenance records are reviewed to identify critical components/failure modes. FMECA was performed for these critical component/failure modes. After reviewing current preventive maintenance activities of Wolsung unit 1, draft RCM recommendations are developed. 6 tabs., 16 refs. (Author).

Propagated failure analysis for non-repairable systems considering both global and selective effects

International Nuclear Information System (INIS)

Wang Chaonan; Xing Liudong; Levitin, Gregory

2012-01-01

This paper proposes an algorithm for the reliability analysis of non-repairable binary systems subject to competing failure propagation and failure isolation events with both global and selective failure effects. A propagated failure that originates from a system component causes extensive damage to the rest of the system. Global effect happens when the propagated failure causes the entire system to fail; whereas selective effect happens when the propagated failure causes only failure of a subset of system components. In both cases, the failure propagation that originates from some system components (referred to as dependent components) can be isolated because of functional dependence between the dependent components and a component that prevents the failure propagation (trigger components) when the failure of the trigger component happens before the occurrence of the propagated failure. Most existing studies focus on the analysis of propagated failures with global effect. However, in many cases, propagated failures affect only a subset of system components not the entire system. Existing approaches for analyzing propagated failures with selective effect are limited to series-parallel systems. This paper proposes a combinatorial method for the propagated failure analysis considering both global and selective effects as well as the competition with the failure isolation in the time domain. The proposed method is not limited to series-parallel systems and has no limitation on the type of time-to-failure distributions for the system components. The method is verified using the Markov-based method. An example of computer memory systems is analyzed to demonstrate the application of the proposed method.

Failure mode and effects analysis of software-based automation systems

International Nuclear Information System (INIS)

Haapanen, P.; Helminen, A.

2002-08-01

Failure mode and effects analysis (FMEA) is one of the well-known analysis methods having an established position in the traditional reliability analysis. The purpose of FMEA is to identify possible failure modes of the system components, evaluate their influences on system behaviour and propose proper countermeasures to suppress these effects. The generic nature of FMEA has enabled its wide use in various branches of industry reaching from business management to the design of spaceships. The popularity and diverse use of the analysis method has led to multiple interpretations, practices and standards presenting the same analysis method. FMEA is well understood at the systems and hardware levels, where the potential failure modes usually are known and the task is to analyse their effects on system behaviour. Nowadays, more and more system functions are realised on software level, which has aroused the urge to apply the FMEA methodology also on software based systems. Software failure modes generally are unknown - 'software modules do not fail, they only display incorrect behaviour' - and depend on dynamic behaviour of the application. These facts set special requirements on the FMEA of software based systems and make it difficult to realise. In this report the failure mode and effects analysis is studied for the use of reliability analysis of software-based systems. More precisely, the target system of FMEA is defined to be a safety-critical software-based automation application in a nuclear power plant, implemented on an industrial automation system platform. Through a literature study the report tries to clarify the intriguing questions related to the practical use of software failure mode and effects analysis. The study is a part of the research project 'Programmable Automation System Safety Integrity assessment (PASSI)', belonging to the Finnish Nuclear Safety Research Programme (FINNUS, 1999-2002). In the project various safety assessment methods and tools for

14 CFR 417.224 - Probability of failure analysis.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Probability of failure analysis. 417.224..., DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.224 Probability of failure..., must account for launch vehicle failure probability in a consistent manner. A launch vehicle failure...

Executive dysfunction is independently associated with reduced functional independence in heart failure.

Science.gov (United States)

Alosco, Michael L; Spitznagel, Mary Beth; Raz, Naftali; Cohen, Ronald; Sweet, Lawrence H; Colbert, Lisa H; Josephson, Richard; van Dulmen, Manfred; Hughes, Joel; Rosneck, Jim; Gunstad, John

2014-03-01

To examine the independent association between executive function with instrumental activities of daily living and health behaviours in older adults with heart failure. Executive function is an important contributor to functional independence as it consists of cognitive processes needed for decision-making, planning, organising and behavioural monitoring. Impairment in this domain is common in heart failure patients and associated with reduced performance of instrumental activities of daily living in many medical and neurological populations. However, the contribution of executive functions to functional independence and healthy lifestyle choices in heart failure patients has not been fully examined. Cross-sectional analyses. One hundred and seventy-five heart failure patients completed a neuropsychological battery and echocardiogram. Participants also completed the Lawton-Brody Instrumental Activities of Daily Living Scale and reported current cigarette use. Hierarchical regressions revealed that reduced executive function was independently associated with worse instrumental activity of daily living performance with a specific association for decreased ability to manage medications. Partial correlations showed that executive dysfunction was associated with current cigarette use. Our findings suggest that executive dysfunction is associated with poorer functional independence and contributes to unhealthy behaviours in heart failure. Future studies should examine whether heart failure patients benefit from formal organisation schema (i.e. pill organisers) to maintain independence. Screening of executive function in heart failure patients may provide key insight into their ability to perform daily tasks, including the management of treatment recommendations. © 2013 John Wiley & Sons Ltd.

Failure and Reliability Analysis for the Master Pump Shutdown System

International Nuclear Information System (INIS)

BEVINS, R.R.

2000-01-01

The Master Pump Shutdown System (MPSS) will be installed in the 200 Areas of the Hanford Site to monitor and control the transfer of liquid waste between tank farms and between the 200 West and 200 East areas through the Cross-Site Transfer Line. The Safety Function provided by the MPSS is to shutdown any waste transfer process within or between tank farms if a waste leak should occur along the selected transfer route. The MPSS, which provides this Safety Class Function, is composed of Programmable Logic Controllers (PLCs), interconnecting wires, relays, Human to Machine Interfaces (HMI), and software. These components are defined as providing a Safety Class Function and will be designated in this report as MPSS/PLC. Input signals to the MPSS/PLC are provided by leak detection systems from each of the tank farm leak detector locations along the waste transfer route. The combination of the MPSS/PLC, leak detection system, and transfer pump controller system will be referred to as MPSS/SYS. The components addressed in this analysis are associated with the MPSS/SYS. The purpose of this failure and reliability analysis is to address the following design issues of the Project Development Specification (PDS) for the MPSS/SYS (HNF 2000a): (1) Single Component Failure Criterion, (2) System Status Upon Loss of Electrical Power, (3) Physical Separation of Safety Class cables, (4) Physical Isolation of Safety Class Wiring from General Service Wiring, and (5) Meeting the MPSS/PLC Option 1b (RPP 1999) Reliability estimate. The failure and reliability analysis examined the system on a component level basis and identified any hardware or software elements that could fail and/or prevent the system from performing its intended safety function

Analysis of unavailability related to demand failures as a function of the testing interval

International Nuclear Information System (INIS)

Carretero, J.A.; Pereira, M.B.; Perez Lobo, E.M.

1998-01-01

The unavailability related to the demand failure of a component is the sum of the contributions of the failures in demand and in waiting. An important point in PSAs is the calculation of unavailabilities of the basic events of demand failure. Several criteria are used for this, with the objective of simplifying said quantification. The information available from two nuclear power plants has been analysed, in order to determine the tendency in the models in demand and in waiting, as a function of the test intervals, the following conclusions were obtained: - There is a clear tendency for the possibility of failure in demand to increase as the interval between tests increases - The test intervals considered in PSAs are not always coherent with the estimates of real demand; this implies a penalty when using the in waiting model, due to the underlying conservatism Therefore, increasing the intervals between tests over time (a tendency studied in nuclear power plants)could cause demand due to tests to b e significantly less than that due to real actuations. This implies a need to apply test intervals based on historic demands and not on those due to historic tests, in order to avoid conservatism. (Author)

Failure Analysis Of Industrial Boiler Pipe

International Nuclear Information System (INIS)

Natsir, Muhammad; Soedardjo, B.; Arhatari, Dewi; Andryansyah; Haryanto, Mudi; Triyadi, Ari

2000-01-01

Failure analysis of industrial boiler pipe has been done. The tested pipe material is carbon steel SA 178 Grade A refer to specification data which taken from Fertilizer Company. Steps in analysis were ; collection of background operation and material specification, visual inspection, dye penetrant test, radiography test, chemical composition test, hardness test, metallography test. From the test and analysis result, it is shown that the pipe failure caused by erosion and welding was shown porosity and incomplete penetration. The main cause of failure pipe is erosion due to cavitation, which decreases the pipe thickness. Break in pipe thickness can be done due to decreasing in pipe thickness. To anticipate this problem, the ppe will be replaced with new pipe

Combinatorial analysis of systems with competing failures subject to failure isolation and propagation effects

International Nuclear Information System (INIS)

Xing Liudong; Levitin, Gregory

2010-01-01

This paper considers the reliability analysis of binary-state systems, subject to propagated failures with global effect, and failure isolation phenomena. Propagated failures with global effect are common-cause failures originated from a component of a system/subsystem causing the failure of the entire system/subsystem. Failure isolation occurs when the failure of one component (referred to as a trigger component) causes other components (referred to as dependent components) within the same system to become isolated from the system. On the one hand, failure isolation makes the isolated dependent components unusable; on the other hand, it prevents the propagation of failures originated from those dependent components. However, the failure isolation effect does not exist if failures originated in the dependent components already propagate globally before the trigger component fails. In other words, there exists a competition in the time domain between the failure of the trigger component that causes failure isolation and propagated failures originated from the dependent components. This paper presents a combinatorial method for the reliability analysis of systems subject to such competing propagated failures and failure isolation effect. Based on the total probability theorem, the proposed method is analytical, exact, and has no limitation on the type of time-to-failure distributions for the system components. An illustrative example is given to demonstrate the basics and advantages of the proposed method.

The failure trace archive : enabling comparative analysis of failures in diverse distributed systems

NARCIS (Netherlands)

Kondo, D.; Javadi, B.; Iosup, A.; Epema, D.H.J.

2010-01-01

With the increasing functionality and complexity of distributed systems, resource failures are inevitable. While numerous models and algorithms for dealing with failures exist, the lack of public trace data sets and tools has prevented meaningful comparisons. To facilitate the design, validation,

Failure rate analysis using GLIMMIX

International Nuclear Information System (INIS)

Moore, L.M.; Hemphill, G.M.; Martz, H.F.

1998-01-01

This paper illustrates use of a recently developed SAS macro, GLIMMIX, for implementing an analysis suggested by Wolfinger and O'Connell (1993) in modeling failure count data with random as well as fixed factor effects. Interest in this software tool arose from consideration of modernizing the Failure Rate Analysis Code (FRAC), developed at Los Alamos National Laboratory in the early 1980's by Martz, Beckman and McInteer (1982). FRAC is a FORTRAN program developed to analyze Poisson distributed failure count data as a log-linear model, possibly with random as well as fixed effects. These statistical modeling assumptions are a special case of generalized linear mixed models, identified as GLMM in the current statistics literature. In the nearly 15 years since FRAC was developed, there have been considerable advances in computing capability, statistical methodology and available statistical software tools allowing worthwhile consideration of the tasks of modernizing FRAC. In this paper, the approaches to GLMM estimation implemented in GLIMMIX and in FRAC are described and a comparison of results for the two approaches is made with data on catastrophic time-dependent pump failures from a report by Martz and Whiteman (1984). Additionally, statistical and graphical model diagnostics are suggested and illustrated with the GLIMMIX analysis results

Failure and damage analysis of advanced materials

CERN Document Server

Sadowski, Tomasz

2015-01-01

The papers in this volume present basic concepts and new developments in failure and damage analysis with focus on advanced materials such as composites, laminates, sandwiches and foams, and also new metallic materials. Starting from some mathematical foundations (limit surfaces, symmetry considerations, invariants) new experimental results and their analysis are shown. Finally, new concepts for failure prediction and analysis will be introduced and discussed as well as new methods of failure and damage prediction for advanced metallic and non-metallic materials. Based on experimental results the traditional methods will be revised.

Failure analysis of real-time systems

International Nuclear Information System (INIS)

Jalashgar, A.; Stoelen, K.

1998-01-01

This paper highlights essential aspects of real-time software systems that are strongly related to the failures and their course of propagation. The significant influence of means-oriented and goal-oriented system views in the description, understanding and analysing of those aspects is elaborated. The importance of performing failure analysis prior to reliability analysis of real-time systems is equally addressed. Problems of software reliability growth models taking the properties of such systems into account are discussed. Finally, the paper presents a preliminary study of a goal-oriented approach to model the static and dynamic characteristics of real-time systems, so that the corresponding analysis can be based on a more descriptive and informative picture of failures, their effects and the possibility of their occurrence. (author)

Constructing Ontology for Knowledge Sharing of Materials Failure Analysis

Directory of Open Access Journals (Sweden)

Peng Shi

2014-01-01

Full Text Available Materials failure indicates the fault with materials or components during their performance. To avoid the reoccurrence of similar failures, materials failure analysis is executed to investigate the reasons for the failure and to propose improved strategies. The whole procedure needs sufficient domain knowledge and also produces valuable new knowledge. However, the information about the materials failure analysis is usually retained by the domain expert, and its sharing is technically difficult. This phenomenon may seriously reduce the efficiency and decrease the veracity of the failure analysis. To solve this problem, this paper adopts ontology, a novel technology from the Semantic Web, as a tool for knowledge representation and sharing and describes the construction of the ontology to obtain information concerning the failure analysis, application area, materials, and failure cases. The ontology represented information is machine-understandable and can be easily shared through the Internet. At the same time, failure case intelligent retrieval, advanced statistics, and even automatic reasoning can be accomplished based on ontology represented knowledge. Obviously this can promote the knowledge sharing of materials service safety and improve the efficiency of failure analysis. The case of a nuclear power plant area is presented to show the details and benefits of this method.

Analysis of failure and maintenance experiences of motor operated valves in a Finnish nuclear power plant

International Nuclear Information System (INIS)

Simola, K.; Laakso, K.

1992-01-01

Operating experiences from 1981 up to 1989 of totally 104 motor operated closing valves (MOV) in different safety systems at TVO I and II nuclear power units were analysed in a systematic way. The qualitative methods used were failure mode and effects analysis (FMEA) and maintenance effects and criticality analysis (MECA). The failure descriptions were obtained from power plant's computerized failure reporting system. The reported 181 failure events were reanalysed and sorted according to specific classifications developed for the MOV function. Filled FMEA and MECA sheets on individual valves were stored in a microcomputer data base for further analyses. Analyses were performed for the failed mechanical and electrical valve parts, ways of detection of failure modes, failure effects, and repair and unavailability times

Data needs for common cause failure analysis

International Nuclear Information System (INIS)

Parry, G.W.; Paula, H.M.; Rasmuson, D.; Whitehead, D.

1990-01-01

The procedures guide for common cause failure analysis published jointly by USNRC and EPRI requires a detailed historical event analysis. Recent work on the further development of the cause-defense picture of common cause failures introduced in that guide identified the information that is necessary to perform the detailed analysis in an objective manner. This paper summarizes these information needs

Standard guide for corrosion-related failure analysis

CERN Document Server

American Society for Testing and Materials. Philadelphia

2000-01-01

1.1 This guide covers key issues to be considered when examining metallic failures when corrosion is suspected as either a major or minor causative factor. 1.2 Corrosion-related failures could include one or more of the following: change in surface appearance (for example, tarnish, rust, color change), pin hole leak, catastrophic structural failure (for example, collapse, explosive rupture, implosive rupture, cracking), weld failure, loss of electrical continuity, and loss of functionality (for example, seizure, galling, spalling, swelling). 1.3 Issues covered include overall failure site conditions, operating conditions at the time of failure, history of equipment and its operation, corrosion product sampling, environmental sampling, metallurgical and electrochemical factors, morphology (mode) or failure, and by considering the preceding, deducing the cause(s) of corrosion failure. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibili...

Integrated failure probability estimation based on structural integrity analysis and failure data: Natural gas pipeline case

International Nuclear Information System (INIS)

Dundulis, Gintautas; Žutautaitė, Inga; Janulionis, Remigijus; Ušpuras, Eugenijus; Rimkevičius, Sigitas; Eid, Mohamed

2016-01-01

In this paper, the authors present an approach as an overall framework for the estimation of the failure probability of pipelines based on: the results of the deterministic-probabilistic structural integrity analysis (taking into account loads, material properties, geometry, boundary conditions, crack size, and defected zone thickness), the corrosion rate, the number of defects and failure data (involved into the model via application of Bayesian method). The proposed approach is applied to estimate the failure probability of a selected part of the Lithuanian natural gas transmission network. The presented approach for the estimation of integrated failure probability is a combination of several different analyses allowing us to obtain: the critical crack's length and depth, the failure probability of the defected zone thickness, dependency of the failure probability on the age of the natural gas transmission pipeline. A model's uncertainty analysis and uncertainty propagation analysis are performed, as well. - Highlights: • Degradation mechanisms of natural gas transmission pipelines. • Fracture mechanic analysis of the pipe with crack. • Stress evaluation of the pipe with critical crack. • Deterministic-probabilistic structural integrity analysis of gas pipeline. • Integrated estimation of pipeline failure probability by Bayesian method.

Preliminary failure mode and effect analysis

International Nuclear Information System (INIS)

Addison, J.V.

1972-01-01

A preliminary Failure Mode and Effect Analysis (FMEA) was made on the overall 5 Kwe system. A general discussion of the system and failure effect is given in addition to the tabulated FMEA and a primary block diagram of the system. (U.S.)

X-framework: Space system failure analysis framework

Science.gov (United States)

Newman, John Steven

Space program and space systems failures result in financial losses in the multi-hundred million dollar range every year. In addition to financial loss, space system failures may also represent the loss of opportunity, loss of critical scientific, commercial and/or national defense capabilities, as well as loss of public confidence. The need exists to improve learning and expand the scope of lessons documented and offered to the space industry project team. One of the barriers to incorporating lessons learned include the way in which space system failures are documented. Multiple classes of space system failure information are identified, ranging from "sound bite" summaries in space insurance compendia, to articles in journals, lengthy data-oriented (what happened) reports, and in some rare cases, reports that treat not only the what, but also the why. In addition there are periodically published "corporate crisis" reports, typically issued after multiple or highly visible failures that explore management roles in the failure, often within a politically oriented context. Given the general lack of consistency, it is clear that a good multi-level space system/program failure framework with analytical and predictive capability is needed. This research effort set out to develop such a model. The X-Framework (x-fw) is proposed as an innovative forensic failure analysis approach, providing a multi-level understanding of the space system failure event beginning with the proximate cause, extending to the directly related work or operational processes and upward through successive management layers. The x-fw focus is on capability and control at the process level and examines: (1) management accountability and control, (2) resource and requirement allocation, and (3) planning, analysis, and risk management at each level of management. The x-fw model provides an innovative failure analysis approach for acquiring a multi-level perspective, direct and indirect causation of

Importance analysis for the systems with common cause failures

International Nuclear Information System (INIS)

Pan Zhijie; Nonaka, Yasuo

1995-01-01

This paper extends the importance analysis technique to the research field of common cause failures to evaluate the structure importance, probability importance, and β-importance for the systems with common cause failures. These importance measures would help reliability analysts to limit the common cause failure analysis framework and find efficient defence strategies against common cause failures

Failure mode analysis using state variables derived from fault trees with application

International Nuclear Information System (INIS)

Bartholomew, R.J.

1982-01-01

Fault Tree Analysis (FTA) is used extensively to assess both the qualitative and quantitative reliability of engineered nuclear power systems employing many subsystems and components. FTA is very useful, but the method is limited by its inability to account for failure mode rate-of-change interdependencies (coupling) of statistically independent failure modes. The state variable approach (using FTA-derived failure modes as states) overcomes these difficulties and is applied to the determination of the lifetime distribution function for a heat pipe-thermoelectric nuclear power subsystem. Analyses are made using both Monte Carlo and deterministic methods and compared with a Markov model of the same subsystem

Goal-oriented failure analysis - a systems analysis approach to hazard identification

International Nuclear Information System (INIS)

Reeves, A.B.; Davies, J.; Foster, J.; Wells, G.L.

1990-01-01

Goal-Oriented Failure Analysis, GOFA, is a methodology which is being developed to identify and analyse the potential failure modes of a hazardous plant or process. The technique will adopt a structured top-down approach, with a particular failure goal being systematically analysed. A systems analysis approach is used, with the analysis being organised around a systems diagram of the plant or process under study. GOFA will also use checklists to supplement the analysis -these checklists will be prepared in advance of a group session and will help to guide the analysis and avoid unnecessary time being spent on identifying obvious failure modes or failing to identify certain hazards or failures. GOFA is being developed with the aim of providing a hazard identification methodology which is more efficient and stimulating than the conventional approach to HAZOP. The top-down approach should ensure that the analysis is more focused and the use of a systems diagram will help to pull the analysis together at an early stage whilst also helping to structure the sessions in a more stimulating way than the conventional techniques. GOFA will be, essentially, an extension of the HAZOP methodology. GOFA is currently being computerised using a knowledge-based systems approach for implementation. The Goldworks II expert systems development tool is being used. (author)

False Positive Functional Analysis Results as a Contributor of Treatment Failure during Functional Communication Training

Science.gov (United States)

Mann, Amanda J.; Mueller, Michael M.

2009-01-01

Research has shown that functional analysis results are beneficial for treatment selection because they identify reinforcers for severe behavior that can then be used to reinforce replacement behaviors either differentially or noncontingently. Theoretically then, if a reinforcer is identified in a functional analysis erroneously, a well researched…

Association between Functional Variables and Heart Failure after Myocardial Infarction in Rats

Energy Technology Data Exchange (ETDEWEB)

Polegato, Bertha F.; Minicucci, Marcos F.; Azevedo, Paula S.; Gonçalves, Andréa F.; Lima, Aline F.; Martinez, Paula F.; Okoshi, Marina P.; Okoshi, Katashi; Paiva, Sergio A. R.; Zornoff, Leonardo A. M., E-mail: lzornoff@fmb.unesp.br [Faculdade de Medicina de Botucatu - Universidade Estadual Paulista ' Júlio de mesquita Filho' - UNESP Botucatu, SP (Brazil)

2016-02-15

Heart failure prediction after acute myocardial infarction may have important clinical implications. To analyze the functional echocardiographic variables associated with heart failure in an infarction model in rats. The animals were divided into two groups: control and infarction. Subsequently, the infarcted animals were divided into groups: with and without heart failure. The predictive values were assessed by logistic regression. The cutoff values predictive of heart failure were determined using ROC curves. Six months after surgery, 88 infarcted animals and 43 control animals were included in the study. Myocardial infarction increased left cavity diameters and the mass and wall thickness of the left ventricle. Additionally, myocardial infarction resulted in systolic and diastolic dysfunction, characterized by lower area variation fraction values, posterior wall shortening velocity, E-wave deceleration time, associated with higher values of E / A ratio and isovolumic relaxation time adjusted by heart rate. Among the infarcted animals, 54 (61%) developed heart failure. Rats with heart failure have higher left cavity mass index and diameter, associated with worsening of functional variables. The area variation fraction, the E/A ratio, E-wave deceleration time and isovolumic relaxation time adjusted by heart rate were functional variables predictors of heart failure. The cutoff values of functional variables associated with heart failure were: area variation fraction < 31.18%; E / A > 3.077; E-wave deceleration time < 42.11 and isovolumic relaxation time adjusted by heart rate < 69.08. In rats followed for 6 months after myocardial infarction, the area variation fraction, E/A ratio, E-wave deceleration time and isovolumic relaxation time adjusted by heart rate are predictors of heart failure onset.

Association between Functional Variables and Heart Failure after Myocardial Infarction in Rats

International Nuclear Information System (INIS)

Polegato, Bertha F.; Minicucci, Marcos F.; Azevedo, Paula S.; Gonçalves, Andréa F.; Lima, Aline F.; Martinez, Paula F.; Okoshi, Marina P.; Okoshi, Katashi; Paiva, Sergio A. R.; Zornoff, Leonardo A. M.

2016-01-01

Heart failure prediction after acute myocardial infarction may have important clinical implications. To analyze the functional echocardiographic variables associated with heart failure in an infarction model in rats. The animals were divided into two groups: control and infarction. Subsequently, the infarcted animals were divided into groups: with and without heart failure. The predictive values were assessed by logistic regression. The cutoff values predictive of heart failure were determined using ROC curves. Six months after surgery, 88 infarcted animals and 43 control animals were included in the study. Myocardial infarction increased left cavity diameters and the mass and wall thickness of the left ventricle. Additionally, myocardial infarction resulted in systolic and diastolic dysfunction, characterized by lower area variation fraction values, posterior wall shortening velocity, E-wave deceleration time, associated with higher values of E / A ratio and isovolumic relaxation time adjusted by heart rate. Among the infarcted animals, 54 (61%) developed heart failure. Rats with heart failure have higher left cavity mass index and diameter, associated with worsening of functional variables. The area variation fraction, the E/A ratio, E-wave deceleration time and isovolumic relaxation time adjusted by heart rate were functional variables predictors of heart failure. The cutoff values of functional variables associated with heart failure were: area variation fraction < 31.18%; E / A > 3.077; E-wave deceleration time < 42.11 and isovolumic relaxation time adjusted by heart rate < 69.08. In rats followed for 6 months after myocardial infarction, the area variation fraction, E/A ratio, E-wave deceleration time and isovolumic relaxation time adjusted by heart rate are predictors of heart failure onset

Improved methods for dependent failure analysis in PSA

International Nuclear Information System (INIS)

Ballard, G.M.; Games, A.M.

1988-01-01

The basic design principle used in ensuring the safe operation of nuclear power plant is defence in depth. This normally takes the form of redundant equipment and systems which provide protection even if a number of equipment failures occur. Such redundancy is particularly effective in ensuring that multiple, independent equipment failures with the potential for jeopardising reactor safety will be rare events. However the achievement of high reliability has served to highlight the potentially dominant role of multiple, dependent failures of equipment and systems. Analysis of reactor operating experience has shown that dependent failure events are the major contributors to safety system failures and reactor incidents and accidents. In parallel PSA studies have shown that the results of a safety analysis are sensitive to assumptions made about the dependent failure (CCF) probability for safety systems. Thus a Westinghouse Analysis showed that increasing system dependent failure probabilities by a factor of 5 led to a factor 4 increase in core. This paper particularly refers to the engineering concepts underlying dependent failure assessment touching briefly on aspects of data. It is specifically not the intent of our work to develop a new mathematical model of CCF but to aid the use of existing models

Failure analysis of parameter-induced simulation crashes in climate models

Science.gov (United States)

Lucas, D. D.; Klein, R.; Tannahill, J.; Ivanova, D.; Brandon, S.; Domyancic, D.; Zhang, Y.

2013-08-01

Simulations using IPCC (Intergovernmental Panel on Climate Change)-class climate models are subject to fail or crash for a variety of reasons. Quantitative analysis of the failures can yield useful insights to better understand and improve the models. During the course of uncertainty quantification (UQ) ensemble simulations to assess the effects of ocean model parameter uncertainties on climate simulations, we experienced a series of simulation crashes within the Parallel Ocean Program (POP2) component of the Community Climate System Model (CCSM4). About 8.5% of our CCSM4 simulations failed for numerical reasons at combinations of POP2 parameter values. We applied support vector machine (SVM) classification from machine learning to quantify and predict the probability of failure as a function of the values of 18 POP2 parameters. A committee of SVM classifiers readily predicted model failures in an independent validation ensemble, as assessed by the area under the receiver operating characteristic (ROC) curve metric (AUC > 0.96). The causes of the simulation failures were determined through a global sensitivity analysis. Combinations of 8 parameters related to ocean mixing and viscosity from three different POP2 parameterizations were the major sources of the failures. This information can be used to improve POP2 and CCSM4 by incorporating correlations across the relevant parameters. Our method can also be used to quantify, predict, and understand simulation crashes in other complex geoscientific models.

Heart failure: when form fails to follow function.

Science.gov (United States)

Katz, Arnold M; Rolett, Ellis L

2016-02-01

Cardiac performance is normally determined by architectural, cellular, and molecular structures that determine the heart's form, and by physiological and biochemical mechanisms that regulate the function of these structures. Impaired adaptation of form to function in failing hearts contributes to two syndromes initially called systolic heart failure (SHF) and diastolic heart failure (DHF). In SHF, characterized by high end-diastolic volume (EDV), the left ventricle (LV) cannot eject a normal stroke volume (SV); in DHF, with normal or low EDV, the LV cannot accept a normal venous return. These syndromes are now generally defined in terms of ejection fraction (EF): SHF became 'heart failure with reduced ejection fraction' (HFrEF) while DHF became 'heart failure with normal or preserved ejection fraction' (HFnEF or HFpEF). However, EF is a chimeric index because it is the ratio between SV--which measures function, and EDV--which measures form. In SHF the LV dilates when sarcomere addition in series increases cardiac myocyte length, whereas sarcomere addition in parallel can cause concentric hypertrophy in DHF by increasing myocyte thickness. Although dilatation in SHF allows the LV to accept a greater venous return, it increases the energy cost of ejection and initiates a vicious cycle that contributes to progressive dilatation. In contrast, concentric hypertrophy in DHF facilitates ejection but impairs filling and can cause heart muscle to deteriorate. Differences in the molecular signals that initiate dilatation and concentric hypertrophy can explain why many drugs that improve prognosis in SHF have little if any benefit in DHF. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

Fibronectin and Kupffer cell function in fulminant hepatic failure

International Nuclear Information System (INIS)

Imawari, M.; Hughes, R.D.; Gove, C.D.; Williams, R.

1985-01-01

The relationship between plasma fibronectin, in vitro plasma opsonic activity, which measures the biological activity of fibronectin, and in vivo Kupffer cell function, as assessed by the systemic clearance of microaggregated [ 125 I]albumin, were determined simultaneously in 15 patients with fulminant hepatic failure and 12 normal subjects. Both the plasma fibronectin and plasma opsonic activity were significantly reduced in patients with fulminant hepatic failure, while the systemic clearance of microaggregated albumin was decreased. There was a significant correlation between plasma fibronectin and the plasma opsonic activity on admission, but no correlation could be detected between either parameter and the clearance of microaggregated albumin. A gelatin-derived plasma expander was shown to block the plasma opsonic activity both in vitro and in vivo. The low plasma fibronectin and decreased clearance of microaggregated albumin in fulminant hepatic failure reflect different aspects of the overall impairment of Kupffer cell function

Reliability analysis for wind turbines with incomplete failure data collected from after the date of initial installation

International Nuclear Information System (INIS)

Guo Haitao; Watson, Simon; Tavner, Peter; Xiang Jiangping

2009-01-01

Reliability has an impact on wind energy project costs and benefits. Both life test data and field failure data can be used for reliability analysis. In wind energy industry, wind farm operators have greater interest in recording wind turbine operating data. However, field failure data may be tainted or incomplete, and therefore it needs a more general mathematical model and algorithms to solve the model. The aim of this paper is to provide a solution to this problem. A three-parameter Weibull failure rate function is discussed for wind turbines and the parameters are estimated by maximum likelihood and least squares. Two populations of German and Danish wind turbines are analyzed. The traditional Weibull failure rate function is also employed for comparison. Analysis shows that the three-parameter Weibull function can obtain more accuracy on reliability growth of wind turbines. This work will be helpful in the understanding of the reliability growth of wind energy systems as wind energy technologies evolving. The proposed three-parameter Weibull function is also applicable to the life test of the components that have been used for a period of time, not only in wind energy but also in other industries

Analysis of Failure Causes and the Criticality Degree of Elements of Motor Vehicle’s Drum Brakes

Directory of Open Access Journals (Sweden)

D. Ćatić

2014-09-01

Full Text Available The introduction of the paper gives the basic concepts, historical development of methods of Fault Tree Analysis - FTA and Failure Modes, Effects and Criticality Analysis - FMECA for analysis of the reliability and safety of technical systems and importance of applying this method is highlighted. Failure analysis is particularly important for systems whose failures lead to the endangerment of people safety, such as, for example, the braking system of motor vehicles. For the failure analysis of the considered device, it is necessary to know the structure, functioning, working conditions and all factors that have a greater or less influence on its reliability. By formation of the fault tree of drum brakes in braking systems of commercial vehicles, it was established a causal relation between the different events that lead to a reduction in performance or complete failure of the braking system. Based on data from exploitation, using FMECA methods, determination of the criticality degree of drum brake’s elements on the reliable and safe operation of the braking system is performed.

Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance

Energy Technology Data Exchange (ETDEWEB)

O' Daniel, Jennifer C., E-mail: jennifer.odaniel@duke.edu; Yin, Fang-Fang

2017-05-01

Purpose: To determine clinic-specific linear accelerator quality assurance (QA) TG-142 test frequencies, to maximize physicist time efficiency and patient treatment quality. Methods and Materials: A novel quantitative approach to failure mode and effect analysis is proposed. Nine linear accelerator-years of QA records provided data on failure occurrence rates. The severity of test failure was modeled by introducing corresponding errors into head and neck intensity modulated radiation therapy treatment plans. The relative risk of daily linear accelerator QA was calculated as a function of frequency of test performance. Results: Although the failure severity was greatest for daily imaging QA (imaging vs treatment isocenter and imaging positioning/repositioning), the failure occurrence rate was greatest for output and laser testing. The composite ranking results suggest that performing output and lasers tests daily, imaging versus treatment isocenter and imaging positioning/repositioning tests weekly, and optical distance indicator and jaws versus light field tests biweekly would be acceptable for non-stereotactic radiosurgery/stereotactic body radiation therapy linear accelerators. Conclusions: Failure mode and effect analysis is a useful tool to determine the relative importance of QA tests from TG-142. Because there are practical time limitations on how many QA tests can be performed, this analysis highlights which tests are the most important and suggests the frequency of testing based on each test's risk priority number.

Quantitative Approach to Failure Mode and Effect Analysis for Linear Accelerator Quality Assurance.

Science.gov (United States)

O'Daniel, Jennifer C; Yin, Fang-Fang

2017-05-01

To determine clinic-specific linear accelerator quality assurance (QA) TG-142 test frequencies, to maximize physicist time efficiency and patient treatment quality. A novel quantitative approach to failure mode and effect analysis is proposed. Nine linear accelerator-years of QA records provided data on failure occurrence rates. The severity of test failure was modeled by introducing corresponding errors into head and neck intensity modulated radiation therapy treatment plans. The relative risk of daily linear accelerator QA was calculated as a function of frequency of test performance. Although the failure severity was greatest for daily imaging QA (imaging vs treatment isocenter and imaging positioning/repositioning), the failure occurrence rate was greatest for output and laser testing. The composite ranking results suggest that performing output and lasers tests daily, imaging versus treatment isocenter and imaging positioning/repositioning tests weekly, and optical distance indicator and jaws versus light field tests biweekly would be acceptable for non-stereotactic radiosurgery/stereotactic body radiation therapy linear accelerators. Failure mode and effect analysis is a useful tool to determine the relative importance of QA tests from TG-142. Because there are practical time limitations on how many QA tests can be performed, this analysis highlights which tests are the most important and suggests the frequency of testing based on each test's risk priority number. Copyright © 2017 Elsevier Inc. All rights reserved.

Causes of liver failure and impact analysis of prognostic risk factors

Directory of Open Access Journals (Sweden)

WU Xiaoqing

2013-04-01

Full Text Available ObjectiveTo perform a retrospective analysis of patients with liver failure to investigate the causative factors and related risk factors that may affect patient prognosis. MethodsThe clinical, demographic, and laboratory data of 79 consecutive patients diagnosed with liver failure and treated at our hospital between January 2010 and January 2012 (58 males and 21 females; age range: 16-74 years old were collected from the medical records. To identify risk factors of liver failure, the patient variables were assessed by Student’s t-test (continuous variables or Chi-squared test (categorical variables. Multivariate logistic regression analysis was used to investigate the relation between patient outcome and independent risk factors. ResultsThe 79 cases of liver failure were grouped according to disease severity: acute liver failure (n=6; 5 died, subacute liver failure (n=35; 19 died, and chronic liver failure (n=38; 28 died. The overall rate of death was 66%. The majority of cases (81% were related to hepatitis B virus infection. While the three groups of liver failure severity did not show significant differences in sex, mean age, occupation, presence of potassium disorder, total bilirubin (TBil or total cholesterol (CHO at admission, or lowest recorded level of CHO during hospitalization, there were significant intergroup differences in highest recorded TBil level, prothrombin activity (PTA at admission, and highest and lowest recorded PTA, and highest recorded level of CHO. Five independent risk factors were identified: the highest recorded TBil level during hospitalization, presence of infection, hepatorenal syndrome, gastrointestinal bleeding, and hepatic encephalopathy. ConclusionThe major cause of liver failure in this cohort of patients was hepatitis infection, and common biomarkers of liver function, such as TBil, CHO and PTA, may indicate patients with poor prognosis despite clinical intervention. Complications should be addressed as

Development of an Automated Technique for Failure Modes and Effect Analysis

DEFF Research Database (Denmark)

Blanke, M.; Borch, Ole; Allasia, G.

1999-01-01

Advances in automation have provided integration of monitoring and control functions to enhance the operator's overview and ability to take remedy actions when faults occur. Automation in plant supervision is technically possible with integrated automation systems as platforms, but new design...... methods are needed to cope efficiently with the complexity and to ensure that the functionality of a supervisor is correct and consistent. In particular these methods are expected to significantly improve fault tolerance of the designed systems. The purpose of this work is to develop a software module...... implementing an automated technique for Failure Modes and Effects Analysis (FMEA). This technique is based on the matrix formulation of FMEA for the investigation of failure propagation through a system. As main result, this technique will provide the design engineer with decision tables for fault handling...

Development of an automated technique for failure modes and effect analysis

DEFF Research Database (Denmark)

Blanke, Mogens; Borch, Ole; Bagnoli, F.

1999-01-01

Advances in automation have provided integration of monitoring and control functions to enhance the operator's overview and ability to take remedy actions when faults occur. Automation in plant supervision is technically possible with integrated automation systems as platforms, but new design...... methods are needed to cope efficiently with the complexity and to ensure that the functionality of a supervisor is correct and consistent. In particular these methods are expected to significantly improve fault tolerance of the designed systems. The purpose of this work is to develop a software module...... implementing an automated technique for Failure Modes and Effects Analysis (FMEA). This technique is based on the matrix formulation of FMEA for the investigation of failure propagation through a system. As main result, this technique will provide the design engineer with decision tables for fault handling...

Comprehensive Deployment Method for Technical Characteristics Base on Multi-failure Modes Correlation Analysis

Science.gov (United States)

Zheng, W.; Gao, J. M.; Wang, R. X.; Chen, K.; Jiang, Y.

2017-12-01

This paper put forward a new method of technical characteristics deployment based on Reliability Function Deployment (RFD) by analysing the advantages and shortages of related research works on mechanical reliability design. The matrix decomposition structure of RFD was used to describe the correlative relation between failure mechanisms, soft failures and hard failures. By considering the correlation of multiple failure modes, the reliability loss of one failure mode to the whole part was defined, and a calculation and analysis model for reliability loss was presented. According to the reliability loss, the reliability index value of the whole part was allocated to each failure mode. On the basis of the deployment of reliability index value, the inverse reliability method was employed to acquire the values of technology characteristics. The feasibility and validity of proposed method were illustrated by a development case of machining centre’s transmission system.

Construct validity of the Heart Failure Screening Tool (Heart-FaST) to identify heart failure patients at risk of poor self-care: Rasch analysis.

Science.gov (United States)

Reynolds, Nicholas A; Ski, Chantal F; McEvedy, Samantha M; Thompson, David R; Cameron, Jan

2018-02-14

The aim of this study was to psychometrically evaluate the Heart Failure Screening Tool (Heart-FaST) via: (1) examination of internal construct validity; (2) testing of scale function in accordance with design; and (3) recommendation for change/s, if items are not well adjusted, to improve psychometric credential. Self-care is vital to the management of heart failure. The Heart-FaST may provide a prospective assessment of risk, regarding the likelihood that patients with heart failure will engage in self-care. Psychometric validation of the Heart-FaST using Rasch analysis. The Heart-FaST was administered to 135 patients (median age = 68, IQR = 59-78 years; 105 males) enrolled in a multidisciplinary heart failure management program. The Heart-FaST is a nurse-administered tool for screening patients with HF at risk of poor self-care. A Rasch analysis of responses was conducted which tested data against Rasch model expectations, including whether items serve as unbiased, non-redundant indicators of risk and measure a single construct and that rating scales operate as intended. The results showed that data met Rasch model expectations after rescoring or deleting items due to poor discrimination, disordered thresholds, differential item functioning, or response dependence. There was no evidence of multidimensionality which supports the use of total scores from Heart-FaST as indicators of risk. Aggregate scores from this modified screening tool rank heart failure patients according to their "risk of poor self-care" demonstrating that the Heart-FaST items constitute a meaningful scale to identify heart failure patients at risk of poor engagement in heart failure self-care. © 2018 John Wiley & Sons Ltd.

Relationship of hemoglobin and hematocrit to systolic function in advanced heart failure.

Science.gov (United States)

Guglin, Maya; Darbinyan, Nellie

2012-01-01

The dataset from the Evaluation Study of Congestive Heart Failure and Pulmonary Artery Catheterization Effectiveness (ESCAPE) trial provides a rare opportunity to evaluate the whole spectrum of associations of hemoglobin (HB) and hematocrit (HCT) in heart failure (HF). In that trial, subjective and objective data were recorded at multiple time points when HB and HCT were also measured. We investigated the relationship between anemia and ventricular systolic function. A limited access dataset from the ESCAPE trial, provided by the National Heart, Lung and Blood Institute, was analyzed. Linear regression analysis, correlation coefficients and Student's t test were utilized. Besides the known association of anemia with poor prognosis, more severe symptoms, decreased functional capacity and impaired kidney function, we found a significant and very consistent inverse correlation between HB and HCT and ventricular contractility. Both left ventricular ejection fraction and right ventricular fractional area change improved with a decrease in HB and vice versa. We hypothesize that this effect can result from a change in viscosity, which decreases with a decrease in HCT, and may facilitate adaptation of the heart to a volume overload state accompanied by hemodilution. In HF, anemia is associated with poor prognosis and functional impairment, but also with mildly improved systolic function. It may represent an adaptive reaction to congestion. Copyright © 2012 S. Karger AG, Basel.

Cannabidiol improves brain and liver function in a fulminant hepatic failure-induced model of hepatic encephalopathy in mice.

Science.gov (United States)

Avraham, Y; Grigoriadis, Nc; Poutahidis, T; Vorobiev, L; Magen, I; Ilan, Y; Mechoulam, R; Berry, Em

2011-04-01

Hepatic encephalopathy is a neuropsychiatric disorder of complex pathogenesis caused by acute or chronic liver failure. We investigated the effects of cannabidiol, a non-psychoactive constituent of Cannabis sativa with anti-inflammatory properties that activates the 5-hydroxytryptamine receptor 5-HT(1A) , on brain and liver functions in a model of hepatic encephalopathy associated with fulminant hepatic failure induced in mice by thioacetamide. Female Sabra mice were injected with either saline or thioacetamide and were treated with either vehicle or cannabidiol. Neurological and motor functions were evaluated 2 and 3 days, respectively, after induction of hepatic failure, after which brains and livers were removed for histopathological analysis and blood was drawn for analysis of plasma liver enzymes. In a separate group of animals, cognitive function was tested after 8 days and brain 5-HT levels were measured 12 days after induction of hepatic failure. Neurological and cognitive functions were severely impaired in thioacetamide-treated mice and were restored by cannabidiol. Similarly, decreased motor activity in thioacetamide-treated mice was partially restored by cannabidiol. Increased plasma levels of ammonia, bilirubin and liver enzymes, as well as enhanced 5-HT levels in thioacetamide-treated mice were normalized following cannabidiol administration. Likewise, astrogliosis in the brains of thioacetamide-treated mice was moderated after cannabidiol treatment. Cannabidiol restores liver function, normalizes 5-HT levels and improves brain pathology in accordance with normalization of brain function. Therefore, the effects of cannabidiol may result from a combination of its actions in the liver and brain. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

Lessons learned from failure analysis

International Nuclear Information System (INIS)

Le May, I.

2006-01-01

Failure analysis can be a very useful tool to designers and operators of plant and equipment. It is not simply something that is done for lawyers and insurance companies, but is a tool from which lessons can be learned and by means of which the 'breed' can be improved. In this presentation, several failure investigations that have contributed to understanding will be presented. Specifically, the following cases will be discussed: 1) A fire at a refinery that occurred in a desulphurization unit. 2) The failure of a pipeline before it was even put into operation. 3) Failures in locomotive axles that took place during winter operation. The refinery fire was initially blamed on defective Type 321 seamless stainless steel tubing, but there were conflicting views between 'experts' involved as to the mechanism of failure and the writer was called upon to make an in-depth study. This showed that there were a variety of failure mechanism involved, including high temperature fracture, environmentally-induced cracking and possible manufacturing defects. The unraveling of the failure sequence is described and illustrated. The failure of an oil transmission was discovered when the line was pressure tested some months after it had been installed and before it was put into service. Repairs were made and failure occurred in another place upon the next pressure test being conducted. After several more repairs had been made the line was abandoned and a lawsuit was commenced on the basis that the steel was defective. An investigation disclosed that the material was sensitive to embrittlement and the causes of this were determined. As a result, changes were made in the microstructural control of the product to avoid similar problems in future. A series of axle failures occurred in diesel electric locomotives during winter. An investigation was made to determine the nature of the failures which were not by classical fatigue, nor did they correspond to published illustrations of Cu

Failure analysis for WWER-fuel elements

International Nuclear Information System (INIS)

Boehmert, J.; Huettig, W.

1986-10-01

If the fuel defect rate proves significantly high, failure analysis has to be performed in order to trace down the defect causes, to implement corrective actions, and to take measures of failure prevention. Such analyses are work-consuming and very skill-demanding technical tasks, which require examination methods and devices excellently developed and a rich stock of experience in evaluation of features of damage. For that this work specifies the procedure of failure analyses in detail. Moreover prerequisites and experimental equipment for the investigation of WWER-type fuel elements are described. (author)

failure analysis of a uav flight control system using markov analysis

African Journals Online (AJOL)

Failure analysis of a flight control system proposed for Air Force Institute of Technology (AFIT) Unmanned Aerial Vehicle (UAV) was studied using Markov Analysis (MA). It was perceived that understanding of the number of failure states and the probability of being in those state are of paramount importance in order to ...

Association between left ventricular dysfunction, anemia, and chronic renal failure. Analysis of the Heart Failure Prevalence and Predictors in Turkey (HAPPY) cohort.

Science.gov (United States)

Kepez, A; Mutlu, B; Degertekin, M; Erol, C

2015-06-01

Anemia and chronic renal failure (CRF) are frequent comorbidities in patients with heart failure (HF), and they have been reported to be associated with increased mortality and hospitalization rates. HF, anemia, and CRF have been reported to interact with each other forming a vicious cycle termed cardio-renal-anemia syndrome. The aim of the present study was to evaluate the association of HF, anemia, and CRF using data from the large-scale"Heart Failure Prevalence and Predictors in Turkey (HAPPY)" study. Among the HAPPY cohort, 3,369 subjects who had either left ventricular dysfunction (LVD) or normal left ventricular function on echocardiography or normal serum NT-proBNP levels were included in this analysis. The prevalence of anemia and CRF was significantly higher in patients with LVD compared with subjects with normal ventricular function (20.7 % vs. 4.0 % and 19.0 % vs. 3.7 %, respectively; p renal-anemia syndrome and the necessity of treating these comorbidities in patients with HF.

Statistical analysis of events related to emergency diesel generators failures in the nuclear industry

Energy Technology Data Exchange (ETDEWEB)

Kančev, Duško, E-mail: dusko.kancev@ec.europa.eu [European Commission, DG-JRC, Institute for Energy and Transport, P.O. Box 2, NL-1755 ZG Petten (Netherlands); Duchac, Alexander; Zerger, Benoit [European Commission, DG-JRC, Institute for Energy and Transport, P.O. Box 2, NL-1755 ZG Petten (Netherlands); Maqua, Michael [Gesellschaft für Anlagen-und-Reaktorsicherheit (GRS) mbH, Schwetnergasse 1, 50667 Köln (Germany); Wattrelos, Didier [Institut de Radioprotection et de Sûreté Nucléaire (IRSN), BP 17 - 92262 Fontenay-aux-Roses Cedex (France)

2014-07-01

Highlights: • Analysis of operating experience related to emergency diesel generators events at NPPs. • Four abundant operating experience databases screened. • Delineating important insights and conclusions based on the operating experience. - Abstract: This paper is aimed at studying the operating experience related to emergency diesel generators (EDGs) events at nuclear power plants collected from the past 20 years. Events related to EDGs failures and/or unavailability as well as all the supporting equipment are in the focus of the analysis. The selected operating experience was analyzed in detail in order to identify the type of failures, attributes that contributed to the failure, failure modes potential or real, discuss risk relevance, summarize important lessons learned, and provide recommendations. The study in this particular paper is tightly related to the performing of statistical analysis of the operating experience. For the purpose of this study EDG failure is defined as EDG failure to function on demand (i.e. fail to start, fail to run) or during testing, or an unavailability of an EDG, except of unavailability due to regular maintenance. The Gesellschaft für Anlagen und Reaktorsicherheit mbH (GRS) and Institut de Radioprotection et de Sûreté Nucléaire (IRSN) databases as well as the operating experience contained in the IAEA/NEA International Reporting System for Operating Experience and the U.S. Licensee Event Reports were screened. The screening methodology applied for each of the four different databases is presented. Further on, analysis aimed at delineating the causes, root causes, contributing factors and consequences are performed. A statistical analysis was performed related to the chronology of events, types of failures, the operational circumstances of detection of the failure and the affected components/subsystems. The conclusions and results of the statistical analysis are discussed. The main findings concerning the testing

Statistical analysis of events related to emergency diesel generators failures in the nuclear industry

International Nuclear Information System (INIS)

Kančev, Duško; Duchac, Alexander; Zerger, Benoit; Maqua, Michael; Wattrelos, Didier

2014-01-01

Highlights: • Analysis of operating experience related to emergency diesel generators events at NPPs. • Four abundant operating experience databases screened. • Delineating important insights and conclusions based on the operating experience. - Abstract: This paper is aimed at studying the operating experience related to emergency diesel generators (EDGs) events at nuclear power plants collected from the past 20 years. Events related to EDGs failures and/or unavailability as well as all the supporting equipment are in the focus of the analysis. The selected operating experience was analyzed in detail in order to identify the type of failures, attributes that contributed to the failure, failure modes potential or real, discuss risk relevance, summarize important lessons learned, and provide recommendations. The study in this particular paper is tightly related to the performing of statistical analysis of the operating experience. For the purpose of this study EDG failure is defined as EDG failure to function on demand (i.e. fail to start, fail to run) or during testing, or an unavailability of an EDG, except of unavailability due to regular maintenance. The Gesellschaft für Anlagen und Reaktorsicherheit mbH (GRS) and Institut de Radioprotection et de Sûreté Nucléaire (IRSN) databases as well as the operating experience contained in the IAEA/NEA International Reporting System for Operating Experience and the U.S. Licensee Event Reports were screened. The screening methodology applied for each of the four different databases is presented. Further on, analysis aimed at delineating the causes, root causes, contributing factors and consequences are performed. A statistical analysis was performed related to the chronology of events, types of failures, the operational circumstances of detection of the failure and the affected components/subsystems. The conclusions and results of the statistical analysis are discussed. The main findings concerning the testing

Prognosis for recovery of function in acute renal failure

International Nuclear Information System (INIS)

Harwood, T.H. Jr.; Hiesterman, D.R.; Robinson, R.G.; Cross, D.E.; Whittier, F.C.; Diederich, D.A.; Grantham, J.J.

1976-01-01

Twenty-four survivors of acute, nonobstructive, nonnephritic renal failure had a renal scan using iodohippurate sodium I 131 performed early in the acute illness. Scans were judged according to whether the renal images were prominent, faint, or absent during the first 30 minutes after intravenous injection of 100 to 250 microcuries of iodohippurate sodium I 131. All ten patients with prominent renal images attained life-sustaining renal function with an average postrecovery creatinine clearance of 80 ml/min. Of the seven patients with faint renal images, six recovered life-sustaining renal function (average creatinine clearance of 39 ml/min), and one required chronic hemodialysis. Seven patients had no renal image initially; four recovered life-sustaining renal function with an average creatinine clearance of 25 ml/min; three required chronic hemodialysis. We conclude that, for patients with acute renal failure, the appearance of the renal image obtained using this substance is an important indicator of renal viability and of the likelihood for functional recovery

The effect of chronic digitalization on pump function in systolic heart failure.

Science.gov (United States)

Hassapoyannes, C A; Easterling, B M; Chavda, K; Chavda, K K; Movahed, M R; Welch, G W

2001-10-01

Short- and intermediate-term use of cardiac glycosides promotes inotropy and improves the ejection fraction in systolic heart failure. To determine whether chronic digitalization alters left ventricular function and performance. Eighty patients with mild-to-moderate systolic heart failure (baseline ejection fraction < or =45%) participated from our institution in a multi-center, chronic, randomized, double-blind study of digitalis vs. placebo. Of the 40 survivors, 38 (20 allocated to the digitalis arm and 18 to the placebo arm) were evaluated at the end of follow-up (mean, 48.4 months). Left ventricular systolic function was assessed by both nuclear ventriculography and echocardiography. The ejection fraction was measured scintigraphically, while the ventricular volumes were computed echocardiographically. The groups did not differ, at baseline or end-of-study, with respect to the ejection fraction and the loading conditions (arterial pressure, ventricular volumes and heart rate) by either intention-to-treat or actual-treatment-received analysis. Over the course of the trial, the digitalis arm exhibited no significant increase in the use of diuretics (18%, P=0.33), in distinction from the placebo group (78%, P=0.004), and a longer stay on study drug among those patients who withdrew from double-blind treatment (28.6 vs. 11.4 months, P=0.01). Following chronic use of digitalis for mild-to-moderate heart failure, cross-sectional comparison with a control group from the same inception cohort showed no appreciable difference in systolic function or performance. Thus, the suggested clinical benefit cannot be explained by an inotropic effect.

Modelling injection moulding machines for micro manufacture applications through functional analysis

DEFF Research Database (Denmark)

Fantoni, G.; Tosello, Guido; Gabelloni, D.

2012-01-01

The paper presents the analysis of an injection moulding machine using functional analysis to identify both its critical components and possible working problems when such a machine is employed for the production of polymer-based micro products. The step-by-step procedure starts from the study...... of the process phases of a machine and then it employs functional analysis to decompose the phases and attributes functions to part features. Part features are subsequently analyzed to understand the causal chains bringing either to the desired behaviour or to failures to avoid. The assessment of the design...... solution is finally performed by gathering quantitative data from experiments. The case study investigates the design motivations and functional drivers of a micro injection moulding machine. The analysis allows identifying the correlations between failures and advantages with the design of the machine...

The use of lifetime functions in the optimization of interventions on existing bridges considering maintenance and failure costs

Energy Technology Data Exchange (ETDEWEB)

Yang, Seung-Ie [Department of Civil, Enviromental, and Architectural Enginnering, University of Colorado, Campus Box 428, Boulder, CO 80309-0428 (United States)]. E-mail: yangsione@dreamwiz.com; Frangopol, Dan M. [Department of Civil, Enviromental, and Architectural Enginnering, University of Colorado, Campus Box 428, Boulder, CO 80309-0428 (United States)]. E-mail: dan.frangopol@colorado.edu; Kawakami, Yoriko [Hanshin Expressway Public Corporation, Kobe Maintenance Department, 16-1 Shinko-cho Chuo-ku Kobe City, Hyogo, 650-0041 (Japan)]. E-mail: yoriko-kawakami@hepc.go.jp; Neves, Luis C. [Department of Civil, Enviromental, and Architectural Enginnering, University of Colorado, Campus Box 428, Boulder, CO 80309-0428 (United States)]. E-mail: lneves@civil.uminho.pt

2006-06-15

In the last decade, it became clear that life-cycle cost analysis of existing civil infrastructure must be used to optimally manage the growing number of aging and deteriorating structures. The uncertainties associated with deteriorating structures require the use of probabilistic methods to properly evaluate their lifetime performance. In this paper, the deterioration and the effect of maintenance actions are analyzed considering the performance of existing structures characterized by lifetime functions. These functions allow, in a simple manner, the consideration of the effect of aging on the decrease of the probability of survival of a structure, as well as the effect of maintenance actions. Models for the effects of proactive and reactive preventive maintenance, and essential maintenance actions are presented. Since the probability of failure is different from zero during the entire service life of a deteriorating structure and depends strongly on the maintenance strategy, the cost of failure is included in this analysis. The failure of one component in a structure does not usually lead to failure of the structure and, as a result, the safety of existing structures must be analyzed using a system reliability framework. The optimization consists of minimizing the sum of the cumulative maintenance and expected failure cost during the prescribed time horizon. Two examples of application of the proposed methodology are presented. In the first example, the sum of the maintenance and failure costs of a bridge in Colorado is minimized considering essential maintenance only and a fixed minimum acceptable probability of failure. In the second example, the expected lifetime cost, including maintenance and expected failure costs, of a multi-girder bridge is minimized considering reactive preventive maintenance actions.

The use of lifetime functions in the optimization of interventions on existing bridges considering maintenance and failure costs

International Nuclear Information System (INIS)

Yang, Seung-Ie; Frangopol, Dan M.; Kawakami, Yoriko; Neves, Luis C.

2006-01-01

In the last decade, it became clear that life-cycle cost analysis of existing civil infrastructure must be used to optimally manage the growing number of aging and deteriorating structures. The uncertainties associated with deteriorating structures require the use of probabilistic methods to properly evaluate their lifetime performance. In this paper, the deterioration and the effect of maintenance actions are analyzed considering the performance of existing structures characterized by lifetime functions. These functions allow, in a simple manner, the consideration of the effect of aging on the decrease of the probability of survival of a structure, as well as the effect of maintenance actions. Models for the effects of proactive and reactive preventive maintenance, and essential maintenance actions are presented. Since the probability of failure is different from zero during the entire service life of a deteriorating structure and depends strongly on the maintenance strategy, the cost of failure is included in this analysis. The failure of one component in a structure does not usually lead to failure of the structure and, as a result, the safety of existing structures must be analyzed using a system reliability framework. The optimization consists of minimizing the sum of the cumulative maintenance and expected failure cost during the prescribed time horizon. Two examples of application of the proposed methodology are presented. In the first example, the sum of the maintenance and failure costs of a bridge in Colorado is minimized considering essential maintenance only and a fixed minimum acceptable probability of failure. In the second example, the expected lifetime cost, including maintenance and expected failure costs, of a multi-girder bridge is minimized considering reactive preventive maintenance actions

Failure analysis of prestressed concrete beam under impact loading

International Nuclear Information System (INIS)

Ishikawa, N.; Sonoda, Y.; Kobayashi, N.

1993-01-01

This paper presents a failure analysis of prestressed concrete (PC) beam under impact loading. At first, the failure analysis of PC beam section is performed by using the discrete section element method in order to obtain the dynamic bending moment-curvature relation. Secondary, the failure analysis of PC beam is performed by using the rigid panel-spring model. Finally, the numerical calculation is executed and is compared with the experimental results. It is found that this approach can simulate well the experiments at the local and overall failure of the PC beam as well as the impact load and the displacement-time relations. (author)

Micromechanics Based Failure Analysis of Heterogeneous Materials

Science.gov (United States)

Sertse, Hamsasew M.

are performed for both brittle failure/high cycle fatigue (HCF) for negligible plastic strain and ductile failure/low cycle fatigue (LCF) for large plastic strain. The proposed approach is incorporated in SwiftComp and used to predict the initial failure envelope, stress-strain curve for various loading conditions, and fatigue life of heterogeneous materials. The combined effects of strain hardening and progressive fatigue damage on the effective properties of heterogeneous materials are also studied. The capability of the current approach is validated using several representative examples of heterogeneous materials including binary composites, continuous fiber-reinforced composites, particle-reinforced composites, discontinuous fiber-reinforced composites, and woven composites. The predictions of MSG are also compared with the predictions obtained using various micromechanics approaches such as Generalized Methods of Cells (GMC), Mori-Tanaka (MT), and Double Inclusions (DI) and Representative Volume Element (RVE) Analysis (called as 3-dimensional finite element analysis (3D FEA) in this document). This study demonstrates that a micromechanics based failure analysis has a great potential to rigorously and more accurately analyze initiation and progression of damage in heterogeneous materials. However, this approach requires material properties specific to damage analysis, which are needed to be independently calibrated for each constituent.

Geotechnical Failure of a Concrete Crown Wall on a Rubble Mound Breakwater Considering Sliding Failure and Rupture Failure of Foundation

DEFF Research Database (Denmark)

Christiani, E.; Burcharth, H. F.; Sørensen, John Dalsgaard

1995-01-01

Sliding and rupture failure in the rubble mound are considered in this paper. In order to describe these failure modes the wave breaking forces have to be accounted for. Wave breaking forces on a crown wall are determined from Burcharth's wave force formula Burcharth (1992). Overtopping rates...... are calculated for a given design by Bradbury et al. (1988a,b) and compared to acceptable overtopping rates, prior to a determininstic design. The method of foundation stability analysis is presented by the example of a translation slip failure involving kinematically correct slip surfaces and failure zones...... in friction based soil. Rupture failure modes for a crown wall with a plane base and a crown wall with an extended leg on the seaward side will be formulated. The failure modes are described by limit state functions. This allows a deterministic analysis to be performed....

Sensitivity analysis of repairable redundant system with switching failure and geometric reneging

Directory of Open Access Journals (Sweden)

Chandra Shekhar

2017-09-01

Full Text Available This study deals with the performance modeling and reliability analysis of a redundant machining system composed of several functional machines. To analyze the more realistic scenarios, the concepts of switching failure and geometric reneging are included. The time-to-breakdown and repair time of operating and standby machines are assumed to follow the exponential distribution. For the quantitative assessment of the machine interference problem, various performance measures such as mean-time-to-failure, reliability, reneging rate, etc. have been formulated. To show the practicability of the developed model, a numerical illustration has been presented. For the practical justification and validity of the results established, the sensitivity analysis of reliability indices has been presented by varying different system descriptors.

Debugging Nondeterministic Failures in Linux Programs through Replay Analysis

Directory of Open Access Journals (Sweden)

Shakaiba Majeed

2018-01-01

Full Text Available Reproducing a failure is the first and most important step in debugging because it enables us to understand the failure and track down its source. However, many programs are susceptible to nondeterministic failures that are hard to reproduce, which makes debugging extremely difficult. We first address the reproducibility problem by proposing an OS-level replay system for a uniprocessor environment that can capture and replay nondeterministic events needed to reproduce a failure in Linux interactive and event-based programs. We then present an analysis method, called replay analysis, based on the proposed record and replay system to diagnose concurrency bugs in such programs. The replay analysis method uses a combination of static analysis, dynamic tracing during replay, and delta debugging to identify failure-inducing memory access patterns that lead to concurrency failure. The experimental results show that the presented record and replay system has low-recording overhead and hence can be safely used in production systems to catch rarely occurring bugs. We also present few concurrency bug case studies from real-world applications to prove the effectiveness of the proposed bug diagnosis framework.

Uncertainty analysis with statistically correlated failure data

International Nuclear Information System (INIS)

Modarres, M.; Dezfuli, H.; Roush, M.L.

1987-01-01

Likelihood of occurrence of the top event of a fault tree or sequences of an event tree is estimated from the failure probability of components that constitute the events of the fault/event tree. Component failure probabilities are subject to statistical uncertainties. In addition, there are cases where the failure data are statistically correlated. At present most fault tree calculations are based on uncorrelated component failure data. This chapter describes a methodology for assessing the probability intervals for the top event failure probability of fault trees or frequency of occurrence of event tree sequences when event failure data are statistically correlated. To estimate mean and variance of the top event, a second-order system moment method is presented through Taylor series expansion, which provides an alternative to the normally used Monte Carlo method. For cases where component failure probabilities are statistically correlated, the Taylor expansion terms are treated properly. Moment matching technique is used to obtain the probability distribution function of the top event through fitting the Johnson Ssub(B) distribution. The computer program, CORRELATE, was developed to perform the calculations necessary for the implementation of the method developed. (author)

Failure Modes and Effects Analysis (FMEA): A Bibliography

Science.gov (United States)

2000-01-01

Failure modes and effects analysis (FMEA) is a bottom-up analytical process that identifies process hazards, which helps managers understand vulnerabilities of systems, as well as assess and mitigate risk. It is one of several engineering tools and techniques available to program and project managers aimed at increasing the likelihood of safe and successful NASA programs and missions. This bibliography references 465 documents in the NASA STI Database that contain the major concepts, failure modes or failure analysis, in either the basic index of the major subject terms.

Renal function monitoring in heart failure - what is the optimal frequency? A narrative review.

Science.gov (United States)

Al-Naher, Ahmed; Wright, David; Devonald, Mark Alexander John; Pirmohamed, Munir

2018-01-01

The second most common cause of hospitalization due to adverse drug reactions in the UK is renal dysfunction due to diuretics, particularly in patients with heart failure, where diuretic therapy is a mainstay of treatment regimens. Therefore, the optimal frequency for monitoring renal function in these patients is an important consideration for preventing renal failure and hospitalization. This review looks at the current evidence for optimal monitoring practices of renal function in patients with heart failure according to national and international guidelines on the management of heart failure (AHA/NICE/ESC/SIGN). Current guidance of renal function monitoring is in large part based on expert opinion, with a lack of clinical studies that have specifically evaluated the optimal frequency of renal function monitoring in patients with heart failure. Furthermore, there is variability between guidelines, and recommendations are typically nonspecific. Safer prescribing of diuretics in combination with other antiheart failure treatments requires better evidence for frequency of renal function monitoring. We suggest developing more personalized monitoring rather than from the current medication-based guidance. Such flexible clinical guidelines could be implemented using intelligent clinical decision support systems. Personalized renal function monitoring would be more effective in preventing renal decline, rather than reacting to it. © 2017 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.

Effects of catheter-based renal denervation on heart failure with reduced ejection fraction: a systematic review and meta-analysis.

Science.gov (United States)

Fukuta, Hidekatsu; Goto, Toshihiko; Wakami, Kazuaki; Ohte, Nobuyuki

2017-11-01

Despite the recent advances in the management of heart failure, the mortality of heart failure patients remains high. It is of urgent need to develop new therapy for heart failure. Heart failure is characterized by increased sympathetic activity, and chronic sympathetic activation is involved in the maintenance of the pathological state. Catheter-based renal denervation (RDN) has emerged as an invasive but safe approach that can reduce sympathetic activation. Studies have reported inconsistent results regarding the effect of RDN in heart failure patients due to limited power with small sample sizes. We aimed to conduct a meta-analysis of the effect of RDN on heart failure patients with reduced left ventricular (LV) ejection fraction (EF). An electronic search for studies examining the effect of RDN on LV function in heart failure patients with reduced EF was conducted. Two controlled (80 patients) and 2 uncontrolled studies (21 patients) were included in this meta-analysis. In the pooled analysis, 6 months after RDN, there was a greater increase in EF (weighted mean difference [95% CI] = 8.63 [6.02, 11.24] %) and a greater decrease in LV end-diastolic diameter (-0.58 [-0.83, -0.34] cm) in RDN group than in control group. No serious adverse events such as acute renal artery stenosis and dissection occurred. Our meta-analysis of feasibility studies suggests that RDN may improve LV function in heart failure patients with reduced EF, providing the rationale to conduct next phase trials to confirm the observed potential benefits of RDN.

A meta-analysis of the effects of β-adrenergic blockers in chronic heart failure.

Science.gov (United States)

Zhang, Xiaojian; Shen, Chengwu; Zhai, Shujun; Liu, Yukun; Yue, Wen-Wei; Han, Li

2016-10-01

Adrenergic β-blockers are drugs that bind to, but do not activate β-adrenergic receptors. Instead they block the actions of β-adrenergic agonists and are used for the treatment of various diseases such as cardiac arrhythmias, angina pectoris, myocardial infarction, hypertension, headache, migraines, stress, anxiety, prostate cancer, and heart failure. Several meta-analysis studies have shown that β-blockers improve the heart function and reduce the risks of cardiovascular events, rate of mortality, and sudden death through chronic heart failure (CHF) of patients. The present study identified results from recent meta-analyses of β-adrenergic blockers and their usefulness in CHF. Databases including Medline/Embase/Cochrane Central Register of Controlled Trials (CENTRAL), and PubMed were searched for the periods May, 1985 to March, 2011 and June, 2013 to August, 2015, and a number of studies identified. Results of those studies showed that use of β-blockers was associated with decreased sudden cardiac death in patients with heart failure. However, contradictory results have also been reported. The present meta-analysis aimed to determine the efficacy of β-blockers on mortality and morbidity in patients with heart failure. The results showed that mortality was significantly reduced by β-blocker treatment prior to the surgery of heart failure patients. The results from the meta-analysis studies showed that β-blocker treatment in heart failure patients correlated with a significant decrease in long-term mortality, even in patients that meet one or more exclusion criteria of the MERIT-HF study. In summary, the findings of the current meta-analysis revealed beneficial effects different β-blockers have on patients with heart failure or related heart disease.

Failure Propagation Modeling and Analysis via System Interfaces

Directory of Open Access Journals (Sweden)

Lin Zhao

2016-01-01

Full Text Available Safety-critical systems must be shown to be acceptably safe to deploy and use in their operational environment. One of the key concerns of developing safety-critical systems is to understand how the system behaves in the presence of failures, regardless of whether that failure is triggered by the external environment or caused by internal errors. Safety assessment at the early stages of system development involves analysis of potential failures and their consequences. Increasingly, for complex systems, model-based safety assessment is becoming more widely used. In this paper we propose an approach for safety analysis based on system interface models. By extending interaction models on the system interface level with failure modes as well as relevant portions of the physical system to be controlled, automated support could be provided for much of the failure analysis. We focus on fault modeling and on how to compute minimal cut sets. Particularly, we explore state space reconstruction strategy and bounded searching technique to reduce the number of states that need to be analyzed, which remarkably improves the efficiency of cut sets searching algorithm.

Impact of proof test interval and coverage on probability of failure of safety instrumented function

International Nuclear Information System (INIS)

Jin, Jianghong; Pang, Lei; Hu, Bin; Wang, Xiaodong

2016-01-01

Highlights: • Introduction of proof test coverage makes the calculation of the probability of failure for SIF more accurate. • The probability of failure undetected by proof test is independently defined as P TIF and calculated. • P TIF is quantified using reliability block diagram and simple formula of PFD avg . • Improving proof test coverage and adopting reasonable test period can reduce the probability of failure for SIF. - Abstract: Imperfection of proof test can result in the safety function failure of safety instrumented system (SIS) at any time in its life period. IEC61508 and other references ignored or only elementarily analyzed the imperfection of proof test. In order to further study the impact of the imperfection of proof test on the probability of failure for safety instrumented function (SIF), the necessity of proof test and influence of its imperfection on system performance was first analyzed theoretically. The probability of failure for safety instrumented function resulted from the imperfection of proof test was defined as probability of test independent failures (P TIF ), and P TIF was separately calculated by introducing proof test coverage and adopting reliability block diagram, with reference to the simplified calculation formula of average probability of failure on demand (PFD avg ). Research results show that: the shorter proof test period and the higher proof test coverage indicate the smaller probability of failure for safety instrumented function. The probability of failure for safety instrumented function which is calculated by introducing proof test coverage will be more accurate.

Use of fuel failure correlations in accident analysis

International Nuclear Information System (INIS)

O'Dell, L.D.; Baars, R.E.; Waltar, A.E.

1975-05-01

The MELT-III code for analysis of a Transient Overpower (TOP) accident in an LMFBR is briefly described, including failure criteria currently applied in the code. Preliminary results of calculations exploring failure patterns in time and space in the reactor core are reported and compared for the two empirical fuel failure correlations employed in the code. (U.S.)

Light water reactor lower head failure analysis

International Nuclear Information System (INIS)

Rempe, J.L.; Chavez, S.A.; Thinnes, G.L.

1993-10-01

This document presents the results from a US Nuclear Regulatory Commission-sponsored research program to investigate the mode and timing of vessel lower head failure. Major objectives of the analysis were to identify plausible failure mechanisms and to develop a method for determining which failure mode would occur first in different light water reactor designs and accident conditions. Failure mechanisms, such as tube ejection, tube rupture, global vessel failure, and localized vessel creep rupture, were studied. Newly developed models and existing models were applied to predict which failure mechanism would occur first in various severe accident scenarios. So that a broader range of conditions could be considered simultaneously, calculations relied heavily on models with closed-form or simplified numerical solution techniques. Finite element techniques-were employed for analytical model verification and examining more detailed phenomena. High-temperature creep and tensile data were obtained for predicting vessel and penetration structural response

Light water reactor lower head failure analysis

Energy Technology Data Exchange (ETDEWEB)

Rempe, J.L.; Chavez, S.A.; Thinnes, G.L. [EG and G Idaho, Inc., Idaho Falls, ID (United States)] [and others

1993-10-01

This document presents the results from a US Nuclear Regulatory Commission-sponsored research program to investigate the mode and timing of vessel lower head failure. Major objectives of the analysis were to identify plausible failure mechanisms and to develop a method for determining which failure mode would occur first in different light water reactor designs and accident conditions. Failure mechanisms, such as tube ejection, tube rupture, global vessel failure, and localized vessel creep rupture, were studied. Newly developed models and existing models were applied to predict which failure mechanism would occur first in various severe accident scenarios. So that a broader range of conditions could be considered simultaneously, calculations relied heavily on models with closed-form or simplified numerical solution techniques. Finite element techniques-were employed for analytical model verification and examining more detailed phenomena. High-temperature creep and tensile data were obtained for predicting vessel and penetration structural response.

Diuretic response and renal function in heart failure

NARCIS (Netherlands)

ter Maaten, Jozine Magdalena

2016-01-01

In patients with heart failure fluid overload is a frequently occurring problem, which is among others caused by an impaired function of the heart. This fluid overload may lead to severe dyspnea warranting an acute hospitalization. The first choice treatment of this fluid overload is administration

Lecture notes: meantime to failure analysis

International Nuclear Information System (INIS)

Hanlen, R.C.

1976-01-01

A method is presented which affects the Quality Assurance Engineer's place in management decision making by giving him a working parameter to base sound engineering and management decisions. The theory used in Reliability Engineering to determine the mean-time-to-failure of a component or system is reviewed. The method presented derives the probability density function for the parameter of the exponential distribution. The exponential distribution is commonly used by industry to determine the reliability of a component or system when the failure rate is assumed to be constant. Some examples of N Reactor performance data are used. To be specific: The ball system data with 4.9 x 10 6 unit hours of service and 7 individual failures indicates a demonstrated 98.8 percent reliability at a 95 percent confidence level for a 12 month mission period, and the diesel starts data with 7.2 x 10 5 unit hours of service and 1 failure indicates a demonstrated 94.4 percent reliability at a 95 percent confidence level for a 12 month mission period

SU-E-T-420: Failure Effects Mode Analysis for Trigeminal Neuralgia Frameless Radiosurgery

Energy Technology Data Exchange (ETDEWEB)

Howe, J [Associates In Medical Physics, Louisville, KY (United States)

2015-06-15

Purpose: Functional radiosurgery has been used successfully in the treatment of trigeminal neuralgia but presents significant challenges to ensuring the high prescription dose is delivered accurately. A review of existing practice should help direct the focus of quality improvement for this treatment regime. Method: Failure modes and effects analysis was used to identify the processes in preparing radiosurgery treatment for TN. The map was developed by a multidisciplinary team including: neurosurgeon, radiation oncology, physicist and therapist. Potential failure modes were identified for each step in the process map as well as potential causes and end effect. A risk priority number was assigned to each cause. Results: The process map identified 66 individual steps (see attached supporting document). Corrective actions were developed for areas of high risk priority number. Wrong site treatment is at higher risk for trigeminal neuralgia treatment due to the lack of site specific pathologic imaging on MR and CT – additional site specific checks were implemented to minimize the risk of wrong site treatment. Failed collision checks resulted from an insufficient collision model in the treatment planning system and a plan template was developed to address this problem. Conclusion: Failure modes and effects analysis is an effective tool for developing quality improvement in high risk radiotherapy procedures such as functional radiosurgery.

SU-E-T-420: Failure Effects Mode Analysis for Trigeminal Neuralgia Frameless Radiosurgery

International Nuclear Information System (INIS)

Howe, J

2015-01-01

Purpose: Functional radiosurgery has been used successfully in the treatment of trigeminal neuralgia but presents significant challenges to ensuring the high prescription dose is delivered accurately. A review of existing practice should help direct the focus of quality improvement for this treatment regime. Method: Failure modes and effects analysis was used to identify the processes in preparing radiosurgery treatment for TN. The map was developed by a multidisciplinary team including: neurosurgeon, radiation oncology, physicist and therapist. Potential failure modes were identified for each step in the process map as well as potential causes and end effect. A risk priority number was assigned to each cause. Results: The process map identified 66 individual steps (see attached supporting document). Corrective actions were developed for areas of high risk priority number. Wrong site treatment is at higher risk for trigeminal neuralgia treatment due to the lack of site specific pathologic imaging on MR and CT – additional site specific checks were implemented to minimize the risk of wrong site treatment. Failed collision checks resulted from an insufficient collision model in the treatment planning system and a plan template was developed to address this problem. Conclusion: Failure modes and effects analysis is an effective tool for developing quality improvement in high risk radiotherapy procedures such as functional radiosurgery

Failure analysis and failure prevention in electric power systems

International Nuclear Information System (INIS)

Rau, C.A. Jr.; Becker, D.G.; Besuner, P.M.; Cipolla, R.C.; Egan, G.R.; Gupta, P.; Johnson, D.P.; Omry, U.; Tetelman, A.S.; Rettig, T.W.; Peters, D.C.

1977-01-01

New methods have been developed and applied to better quantify and increase the reliability, safety, and availability of electric power plants. Present and potential problem areas have been identified both by development of an improved computerized data base of malfunctions in nuclear power plants and by detailed metallurgical and mechanical failure analyses of selected problems. Significant advances in the accuracy and speed of structural analyses have been made through development and application of the boundary integral equation and influence function methods of stress and fracture mechanics analyses. The currently specified flaw evaluation procedures of the ASME Boiler and Pressure Vessel Code have been computerized. Results obtained from these procedures for evaluation of specific in-service inspection indications have been compared with results obtained utilizing the improved analytical methods. Mathematical methods have also been developed to describe and analyze the statistical variations in materials properties and in component loading, and uncertainties in the flaw size that might be passed by quality assurance systems. These new methods have been combined to develop accurate failure rate predictions based upon probabilistic fracture mechanics. Improved failure prevention strategies have been formulated by combining probabilistic fracture mechanics and cost optimization techniques. The approach has been demonstrated by optimizing the nondestructive inspection level with regard to both reliability and cost. (Auth.)

A streamlined failure mode and effects analysis

International Nuclear Information System (INIS)

Ford, Eric C.; Smith, Koren; Terezakis, Stephanie; Croog, Victoria; Gollamudi, Smitha; Gage, Irene; Keck, Jordie; DeWeese, Theodore; Sibley, Greg

2014-01-01

Purpose: Explore the feasibility and impact of a streamlined failure mode and effects analysis (FMEA) using a structured process that is designed to minimize staff effort. Methods: FMEA for the external beam process was conducted at an affiliate radiation oncology center that treats approximately 60 patients per day. A structured FMEA process was developed which included clearly defined roles and goals for each phase. A core group of seven people was identified and a facilitator was chosen to lead the effort. Failure modes were identified and scored according to the FMEA formalism. A risk priority number,RPN, was calculated and used to rank failure modes. Failure modes with RPN > 150 received safety improvement interventions. Staff effort was carefully tracked throughout the project. Results: Fifty-two failure modes were identified, 22 collected during meetings, and 30 from take-home worksheets. The four top-ranked failure modes were: delay in film check, missing pacemaker protocol/consent, critical structures not contoured, and pregnant patient simulated without the team's knowledge of the pregnancy. These four failure modes hadRPN > 150 and received safety interventions. The FMEA was completed in one month in four 1-h meetings. A total of 55 staff hours were required and, additionally, 20 h by the facilitator. Conclusions: Streamlined FMEA provides a means of accomplishing a relatively large-scale analysis with modest effort. One potential value of FMEA is that it potentially provides a means of measuring the impact of quality improvement efforts through a reduction in risk scores. Future study of this possibility is needed

A streamlined failure mode and effects analysis.

Science.gov (United States)

Ford, Eric C; Smith, Koren; Terezakis, Stephanie; Croog, Victoria; Gollamudi, Smitha; Gage, Irene; Keck, Jordie; DeWeese, Theodore; Sibley, Greg

2014-06-01

Explore the feasibility and impact of a streamlined failure mode and effects analysis (FMEA) using a structured process that is designed to minimize staff effort. FMEA for the external beam process was conducted at an affiliate radiation oncology center that treats approximately 60 patients per day. A structured FMEA process was developed which included clearly defined roles and goals for each phase. A core group of seven people was identified and a facilitator was chosen to lead the effort. Failure modes were identified and scored according to the FMEA formalism. A risk priority number,RPN, was calculated and used to rank failure modes. Failure modes with RPN > 150 received safety improvement interventions. Staff effort was carefully tracked throughout the project. Fifty-two failure modes were identified, 22 collected during meetings, and 30 from take-home worksheets. The four top-ranked failure modes were: delay in film check, missing pacemaker protocol/consent, critical structures not contoured, and pregnant patient simulated without the team's knowledge of the pregnancy. These four failure modes had RPN > 150 and received safety interventions. The FMEA was completed in one month in four 1-h meetings. A total of 55 staff hours were required and, additionally, 20 h by the facilitator. Streamlined FMEA provides a means of accomplishing a relatively large-scale analysis with modest effort. One potential value of FMEA is that it potentially provides a means of measuring the impact of quality improvement efforts through a reduction in risk scores. Future study of this possibility is needed.

A streamlined failure mode and effects analysis

Energy Technology Data Exchange (ETDEWEB)

Ford, Eric C., E-mail: eford@uw.edu; Smith, Koren; Terezakis, Stephanie; Croog, Victoria; Gollamudi, Smitha; Gage, Irene; Keck, Jordie; DeWeese, Theodore; Sibley, Greg [Department of Radiation Oncology and Molecular Radiation Sciences, Johns Hopkins University, Baltimore, MD 21287 (United States)

2014-06-15

Purpose: Explore the feasibility and impact of a streamlined failure mode and effects analysis (FMEA) using a structured process that is designed to minimize staff effort. Methods: FMEA for the external beam process was conducted at an affiliate radiation oncology center that treats approximately 60 patients per day. A structured FMEA process was developed which included clearly defined roles and goals for each phase. A core group of seven people was identified and a facilitator was chosen to lead the effort. Failure modes were identified and scored according to the FMEA formalism. A risk priority number,RPN, was calculated and used to rank failure modes. Failure modes with RPN > 150 received safety improvement interventions. Staff effort was carefully tracked throughout the project. Results: Fifty-two failure modes were identified, 22 collected during meetings, and 30 from take-home worksheets. The four top-ranked failure modes were: delay in film check, missing pacemaker protocol/consent, critical structures not contoured, and pregnant patient simulated without the team's knowledge of the pregnancy. These four failure modes hadRPN > 150 and received safety interventions. The FMEA was completed in one month in four 1-h meetings. A total of 55 staff hours were required and, additionally, 20 h by the facilitator. Conclusions: Streamlined FMEA provides a means of accomplishing a relatively large-scale analysis with modest effort. One potential value of FMEA is that it potentially provides a means of measuring the impact of quality improvement efforts through a reduction in risk scores. Future study of this possibility is needed.

Risk analysis of geothermal power plants using Failure Modes and Effects Analysis (FMEA) technique

International Nuclear Information System (INIS)

Feili, Hamid Reza; Akar, Navid; Lotfizadeh, Hossein; Bairampour, Mohammad; Nasiri, Sina

2013-01-01

Highlights: • Using Failure Modes and Effects Analysis (FMEA) to find potential failures in geothermal power plants. • We considered 5 major parts of geothermal power plants for risk analysis. • Risk Priority Number (RPN) is calculated for all failure modes. • Corrective actions are recommended to eliminate or decrease the risk of failure modes. - Abstract: Renewable energy plays a key role in the transition toward a low carbon economy and the provision of a secure supply of energy. Geothermal energy is a versatile source as a form of renewable energy that meets popular demand. Since some Geothermal Power Plants (GPPs) face various failures, the requirement of a technique for team engineering to eliminate or decrease potential failures is considerable. Because no specific published record of considering an FMEA applied to GPPs with common failure modes have been found already, in this paper, the utilization of Failure Modes and Effects Analysis (FMEA) as a convenient technique for determining, classifying and analyzing common failures in typical GPPs is considered. As a result, an appropriate risk scoring of occurrence, detection and severity of failure modes and computing the Risk Priority Number (RPN) for detecting high potential failures is achieved. In order to expedite accuracy and ability to analyze the process, XFMEA software is utilized. Moreover, 5 major parts of a GPP is studied to propose a suitable approach for developing GPPs and increasing reliability by recommending corrective actions for each failure mode

Predicting device failure after percutaneous repair of functional mitral regurgitation in advanced heart failure: Implications for patient selection.

Science.gov (United States)

Stolfo, Davide; De Luca, Antonio; Morea, Gaetano; Merlo, Marco; Vitrella, Giancarlo; Caiffa, Thomas; Barbati, Giulia; Rakar, Serena; Korcova, Renata; Perkan, Andrea; Pinamonti, Bruno; Pappalardo, Aniello; Berardini, Alessandra; Biagini, Elena; Saia, Francesco; Grigioni, Francesco; Rapezzi, Claudio; Sinagra, Gianfranco

2018-04-15

Patients with heart failure (HF) and severe symptomatic functional mitral regurgitation (FMR) may benefit from MitraClip implantation. With increasing numbers of patients being treated the success of procedure becomes a key issue. We sought to investigate the pre-procedural predictors of device failure in patients with advanced HF treated with MitraClip. From April 2012 to November 2016, 76 patients with poor functional class (NYHA class III-IV) and severe left ventricular (LV) remodeling underwent MitraClip implantation at University Hospitals of Trieste and Bologna (Italy). Device failure was assessed according to MVARC criteria. Patients were subsequently followed to additionally assess the patient success after 12months. Mean age was 67±12years, the mean Log-EuroSCORE was 23.4±16.5%, and the mean LV end-diastolic volume index and ejection fraction (EF) were 112±33ml/m 2 and 30.6±8.9%, respectively. At short-term evaluation, device failure was observed in 22 (29%) patients. Univariate predictors of device failure were LVEF, LV and left atrial volumes and anteroposterior mitral annulus diameter. Annulus dimension (OR 1.153, 95% CI 1.002-1.327, p=0.043) and LV end-diastolic volume (OR 1.024, 95% CI 1.000-1.049, p=0.049) were the only variables independently associated with the risk of device failure at the multivariate model. Pre-procedural anteroposterior mitral annulus diameter accurately predicted the risk of device failure after MitraClip in the setting of advanced HF. Its assessment might aid the selection of the best candidates to percutaneous correction of FMR. Copyright © 2018 Elsevier B.V. All rights reserved.

Failure analysis of a helicopter's main rotor bearing

International Nuclear Information System (INIS)

Shahzad, M.; Qureshi, A.H.; Waqas, H.; Hussain, N.; Ali, N.

2011-01-01

Presented results report some of the findings of a detailed failure analysis carried out on a main rotor hub assembly, which had symptoms of burning and mechanical damage. The analysis suggests environmental degradation of the grease which causes pitting on bearing-balls. The consequent inefficient lubrication raises the temperature which leads to the smearing of cage material (brass) on the bearing-balls and ultimately causes the failure. The analysis has been supported by the microstructural studies, thermal analysis and micro-hardness testing performed on the affected main rotor bearing parts. (author)

Failure probability analysis of optical grid

Science.gov (United States)

Zhong, Yaoquan; Guo, Wei; Sun, Weiqiang; Jin, Yaohui; Hu, Weisheng

2008-11-01

Optical grid, the integrated computing environment based on optical network, is expected to be an efficient infrastructure to support advanced data-intensive grid applications. In optical grid, the faults of both computational and network resources are inevitable due to the large scale and high complexity of the system. With the optical network based distributed computing systems extensive applied in the processing of data, the requirement of the application failure probability have been an important indicator of the quality of application and an important aspect the operators consider. This paper will present a task-based analysis method of the application failure probability in optical grid. Then the failure probability of the entire application can be quantified, and the performance of reducing application failure probability in different backup strategies can be compared, so that the different requirements of different clients can be satisfied according to the application failure probability respectively. In optical grid, when the application based DAG (directed acyclic graph) is executed in different backup strategies, the application failure probability and the application complete time is different. This paper will propose new multi-objective differentiated services algorithm (MDSA). New application scheduling algorithm can guarantee the requirement of the failure probability and improve the network resource utilization, realize a compromise between the network operator and the application submission. Then differentiated services can be achieved in optical grid.

The prognostic importance of lung function in patients admitted with heart failure

DEFF Research Database (Denmark)

Iversen, Kasper Karmark; Kjaergaard, Jesper; Akkan, Dilek

2010-01-01

The purpose of the present study was to determine the prognostic importance for all-cause mortality of lung function variables obtained by spirometry in an unselected group of patients admitted with heart failure (HF).......The purpose of the present study was to determine the prognostic importance for all-cause mortality of lung function variables obtained by spirometry in an unselected group of patients admitted with heart failure (HF)....

Safety Analysis for PHTS Integrity by the failure of the IHTS function in PGSFR

Energy Technology Data Exchange (ETDEWEB)

Ahn, Sang-Jun; Chang, Won-Pyo; Ha, Kwi-Seok; Kang, Seok Hun; Choi, Chi-Woong; Lee, Kwi Lim; Lee, Seung Won; Jeong, Jae-Ho; Kim, Jin Su; Jeong, Taekyeong [KAERI, Daejeon (Korea, Republic of)

2016-05-15

In this paper, the failure of the heat removal function of the IHTS by the SWR event is assumed. The integrity of the PHTS is analyzed by MARS-LMR code. A sodium is used as a reactor coolant to transfer the core heat to the turbine. It rigorously reacts with a water or steam in chemical and generates the high pressure waves and high temperature reaction heat. While it has an excellent characteristics as a coolant, there is an event to be necessarily considered in the sodium cooled fast reactor design. The Sodium-Water Reaction(SWR) event can be occurred due to the rupture of steam generator tubes. This event threaten the integrity of the Primary Heat Transfer System(PHTS). It is categorized to the loss of heat sink events, which are undercooling the Primary Heat Transfer System(PHTS). In PGSFR, the SWR event can be occurred in the SG. The PHTS is analyzed to the respects of the integrity of the fuel and cladding using the MARS-LMR code. From the analysis results, the peak temperature of the fuel and cladding have a sufficient margin to the safety acceptance criteria 1,237 .deg. C and 1,075 .deg. C, respectively.

Failure mode and effects analysis on typical reactor trip system

International Nuclear Information System (INIS)

Eisawy, E.A.

2010-01-01

An updated failure mode and effects analysis, FMEA , has been performed on a typical reactor trip system. This upgrade helps to avoid system damage and ,as a result, extends the system service life. It also provides for simplified maintenance and surveillance testing. The operating conditions under which the system is to carry out its function and the operational profile expected for the system have been determined. The results of the FMEA have been given in terms of operating states of the subsystem.The results are given in form of table which is set up such that for a given failure one can read across it and determine which items remain operating in the system. From this data one can identify the number of components operating in the system for monitors pressure exceeds the setpoint pressure.

Launch Vehicle Failure Dynamics and Abort Triggering Analysis

Science.gov (United States)

Hanson, John M.; Hill, Ashely D.; Beard, Bernard B.

2011-01-01

Launch vehicle ascent is a time of high risk for an on-board crew. There are many types of failures that can kill the crew if the crew is still on-board when the failure becomes catastrophic. For some failure scenarios, there is plenty of time for the crew to be warned and to depart, whereas in some there is insufficient time for the crew to escape. There is a large fraction of possible failures for which time is of the essence and a successful abort is possible if the detection and action happens quickly enough. This paper focuses on abort determination based primarily on data already available from the GN&C system. This work is the result of failure analysis efforts performed during the Ares I launch vehicle development program. Derivation of attitude and attitude rate abort triggers to ensure that abort occurs as quickly as possible when needed, but that false positives are avoided, forms a major portion of the paper. Some of the potential failure modes requiring use of these triggers are described, along with analysis used to determine the success rate of getting the crew off prior to vehicle demise.

Failure analysis on a ruptured petrochemical pipe

Energy Technology Data Exchange (ETDEWEB)

Harun, Mohd [Industrial Technology Division, Malaysian Nuclear Agency, Ministry of Science, Technology and Innovation Malaysia, Bangi, Kajang, Selangor (Malaysia); Shamsudin, Shaiful Rizam; Kamardin, A. [Univ. Malaysia Perlis, Jejawi, Arau (Malaysia). School of Materials Engineering

2010-08-15

The failure took place on a welded elbow pipe which exhibited a catastrophic transverse rupture. The failure was located on the welding HAZ region, parallel to the welding path. Branching cracks were detected at the edge of the rupture area. Deposits of corrosion products were also spotted. The optical microscope analysis showed the presence of transgranular failures which were related to the stress corrosion cracking (SCC) and were predominantly caused by the welding residual stress. The significant difference in hardness between the welded area and the pipe confirmed the findings. Moreover, the failure was also caused by the low Mo content in the stainless steel pipe which was detected by means of spark emission spectrometer. (orig.)

Corrosion induced failure analysis of subsea pipelines

International Nuclear Information System (INIS)

Yang, Yongsheng; Khan, Faisal; Thodi, Premkumar; Abbassi, Rouzbeh

2017-01-01

Pipeline corrosion is one of the main causes of subsea pipeline failure. It is necessary to monitor and analyze pipeline condition to effectively predict likely failure. This paper presents an approach to analyze the observed abnormal events to assess the condition of subsea pipelines. First, it focuses on establishing a systematic corrosion failure model by Bow-Tie (BT) analysis, and subsequently the BT model is mapped into a Bayesian Network (BN) model. The BN model facilitates the modelling of interdependency of identified corrosion causes, as well as the updating of failure probabilities depending on the arrival of new information. Furthermore, an Object-Oriented Bayesian Network (OOBN) has been developed to better structure the network and to provide an efficient updating algorithm. Based on this OOBN model, probability updating and probability adaptation are performed at regular intervals to estimate the failure probabilities due to corrosion and potential consequences. This results in an interval-based condition assessment of subsea pipeline subjected to corrosion. The estimated failure probabilities would help prioritize action to prevent and control failures. Practical application of the developed model is demonstrated using a case study. - Highlights: • A Bow-Tie (BT) based corrosion failure model linking causation with the potential losses. • A novel Object-Oriented Bayesian Network (OOBN) based corrosion failure risk model. • Probability of failure updating and adaptation with respect to time using OOBN model. • Application of the proposed model to develop and test strategies to minimize failure risk.

Taurine Supplementation Improves Functional Capacity, Myocardial Oxygen Consumption, and Electrical Activity in Heart Failure.

Science.gov (United States)

Ahmadian, Mehdi; Dabidi Roshan, Valiollah; Ashourpore, Eadeh

2017-07-04

Taurine is an amino acid found abundantly in the heart in very high concentrations. It is assumed that taurine contributes to several physiological functions of mammalian cells, such as osmoregulation, anti-inflammation, membrane stabilization, ion transport modulation, and regulation of oxidative stress and mitochondrial protein synthesis. The objective of the current study was to evaluate the effectiveness of taurine supplementation on functional capacity, myocardial oxygen consumption, and electrical activity in patients with heart failure. In a double-blind and randomly designed study, 16 patients with heart failure were assigned to two groups: taurine (TG, n = 8) and placebo (PG, n = 8). TG received 500-mg taurine supplementation three times per day for two weeks. Significant decrease in the values of Q-T segments (p heart failure patients. Together, these findings support the view that taurine improves cardiac function and functional capacity in patients with heart failure. This idea warrants further study.

Failure Modes and Effects Analysis (FMEA) of the Residual Heat Removal System

International Nuclear Information System (INIS)

Eggleston, F.T.

1976-01-01

The Residual Heat Removal System (RHRS) transfer heat from the Reactor Coolant System (RCS) to the reactor plant Component Cooling System (CCS) to reduce the temperature of the RCS at a controlled rate during the second part of normal plant cooldown and maintains the desired temperature until the plant is restarted. By the use of an analytic tool, the Failure Modes and Effects Analysis, it is shown that the RHRS, because of its redundant two train design, is able to accommodate any credible component single failure with the only effect being an extension in the required cooldown time, thus demonstrating the reliability of the RHRS to perform its intended function

Prognostic value of worsening renal function in outpatients with chronic heart failure.

Science.gov (United States)

Pimentel, Rodrigo; Couto, Marta; Laszczyńska, Olga; Friões, Fernando; Bettencourt, Paulo; Azevedo, Ana

2014-09-01

Renal function impairment predicts poor survival in heart failure. Attention has recently shifted to worsening renal function, based mostly on serum creatinine and estimated glomerular filtration rate. We assessed the prognostic effect of worsening renal function in ambulatory heart failure patients. Data from 306 ambulatory patients were abstracted from medical files. Worsening renal function was based on the change in estimated glomerular filtration rate, serum creatinine and urea within 6 months of referral. Prognosis was assessed by the composite endpoint all-cause death or heart failure hospitalization, censored at 2 years. Hazard ratios were estimated for worsening renal function, adjusted for sex, age, diabetes, New York Heart Association class, left ventricular systolic dysfunction, medications and baseline renal function. The agreement among definitions was fair, with kappa coefficients generally not surpassing 0.5. Worsening renal function was associated with poor outcome with adjusted hazard ratios (95% confidence interval) of 3.2 (1.8-5.9) for an increase of serum creatinine >0.3mg/dl; 2.2 (1.3-3.7) for an increase in serum urea >20mg/dl and 1.9 (1.1-3.3) for a decrease in estimated glomerular filtration rate >20%, independent of baseline renal function. The 2-year risk of death/heart failure hospitalization was approximately 50% in patients with an increase in serum creatinine or in serum urea; this positive predictive value was higher than for decreasing estimated glomerular filtration rate. In conclusion, worsening renal function was significantly associated with a worse outcome. Different definitions identified different patients at risk and increasing creatinine/urea performed better than decreasing estimated glomerular filtration rate. Copyright © 2014 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

[Clinical characteristics and medium-term prognosis of patients with heart failure and preserved systolic function. Do they differ in systolic dysfunction?].

Science.gov (United States)

Ojeda, Soledad; Anguita, Manuel; Muñoz, Juan F; Rodríguez, Marcos T; Mesa, Dolores; Franco, Manuel; Ureña, Isabel; Vallés, Federico

2003-11-01

To assess the prevalence, clinical profile and medium-term prognosis in patients with heart failure and preserved systolic ventricular function compared to those with systolic dysfunction. 153 patients were included, 62 with preserved systolic ventricular function (left ventricular ejection fraction > or = 45%) and 91 with impaired systolic ventricular function (left ventricular ejection fraction < 45%). The mean follow-up period was 25 10 months. Mean age was similar (66 10 vs. 65 10; p = 0.54). There was a higher proportion of women among patients with preserved systolic function (53% vs. 28%; p < 0.01). Ischemic and idiopathic cardiomyopathy were the most common causes of heart failure in patients with systolic dysfunction, whereas valvular disease and hypertensive cardiopathy were the most common in patients with preserved systolic function. Angiotensin-converting enzyme inhibitors and beta-blockers were more often prescribed in patients with impaired systolic ventricular function (86% vs. 52%; p < 0.01 and 33% vs. 11%; p < 0.01, respectively). There were no differences between the groups in terms of mortality rate (37% vs. 29%), readmission rate for other causes (29% vs. 23%), readmission rate for heart failure (45% vs. 45%), cumulative survival (51% vs. 62%) and the likelihood of not being readmitted for heart failure (50% vs. 52%). In the multivariate analysis, left ventricular ejection fraction was not a predictor of death or readmission because of heart failure. In a large proportion of patients with heart failure, systolic ventricular function is preserved. Despite the clinical differences between patients with preserved and impaired systolic ventricular function, the medium-term prognosis was similar in both groups.

Dependency Defence and Dependency Analysis Guidance. Volume 2: Appendix 3-8. How to analyse and protect against dependent failures. Summary report of the Nordic Working Group on Common Cause Failure Analysis

International Nuclear Information System (INIS)

Johanson, Gunnar; Hellstroem, Per; Makamo, Tuomas; Bento, Jean-Pierre; Knochenhauer, Michael; Poern, Kurt

2003-10-01

The safety systems in Nordic nuclear power plants are characterised by substantial redundancy and/or diversification in safety critical functions, as well as by physical separation of critical safety systems, including their support functions. Viewed together with the evident additional fact, that the single failure criterion has been systematically applied in the design of safety systems, this means that the plant risk profile as calculated in existing PSA:s is usually strongly dominated by failures caused by dependencies resulting in the loss of more than one system sub. The overall objective with the working group is to support safety by studying potential and real CCF events, process statistical data and report conclusions and recommendations that can improve the understanding of these events eventually resulting in increased safety. The result is intended for application in NPP operation, maintenance, inspection and risk assessments. The NAFCS project is part of the activities of the Nordic PSA Group (NPSAG), and is financed jointly by the Nordic utilities and authorities. The work is divided into one quantitative and one qualitative part with the following specific objectives: Qualitative objectives-The goal with the qualitative analysis is to compile experience data and generate insights in terms of relevant failure mechanisms and effective CCF protection measures. The results shall be presented as a guide with checklists and recommendations on how to identify current CCF protection standard and improvement possibilities regarding CCF defences decreasing the CCF vulnerability. Quantitative objectives-The goal with the quantitative analysis is to prepare a Nordic C-book where quantitative insights as Impact Vectors and CCF parameters for different redundancy levels are presented. Uncertainties in CCF data shall be reduced as much as possible. The high redundancy systems sensitivity to CCF events demand a well structured quantitative analysis in support of

Both in- and out-hospital worsening of renal function predict outcome in patients with heart failure: results from the Coordinating Study Evaluating Outcome of Advising and Counseling in Heart Failure (COACH).

Science.gov (United States)

Damman, Kevin; Jaarsma, Tiny; Voors, Adriaan A; Navis, Gerjan; Hillege, Hans L; van Veldhuisen, Dirk J

2009-09-01

The effect of worsening renal function (WRF) after discharge on outcome in patients with heart failure is unknown. We assessed estimated glomerular filtration rate (eGFR) and serum creatinine at admission, discharge, and 6 and 12 months after discharge, in 1023 heart failure patients. Worsening renal function was defined as an increase in serum creatinine of >26.5 micromol/L and >25%. The primary endpoint was a composite of all-cause mortality and heart failure admissions. The mean age of patients was 71 +/- 11 years, and 62% was male. Mean eGFR at admission was 55 +/- 21 mL/min/1.73 m(2). In-hospital WRF occurred in 11% of patients, while 16 and 9% experienced WRF from 0 to 6, and 6 to 12 months after discharge, respectively. In multivariate landmark analysis, WRF at any point in time was associated with a higher incidence of the primary endpoint: hazard ratio (HR) 1.63 (1.10-2.40), P = 0.014 for in-hospital WRF, HR 2.06 (1.13-3.74), P = 0.018 for WRF between 0-6 months, and HR 5.03 (2.13-11.88), P < 0.001 for WRF between 6-12 months. Both in- and out-hospital worsening of renal function are independently related to poor prognosis in patients with heart failure, suggesting that renal function in heart failure patients should be monitored long after discharge.

Computer aided approach to qualitative and quantitative common cause failure analysis for complex systems

International Nuclear Information System (INIS)

Cate, C.L.; Wagner, D.P.; Fussell, J.B.

1977-01-01

Common cause failure analysis, also called common mode failure analysis, is an integral part of a complete system reliability analysis. Existing methods of computer aided common cause failure analysis are extended by allowing analysis of the complex systems often encountered in practice. The methods aid in identifying potential common cause failures and also address quantitative common cause failure analysis

Role of scanning electron microscope )SEM) in metal failure analysis

International Nuclear Information System (INIS)

Shaiful Rizam Shamsudin; Hafizal Yazid; Mohd Harun; Siti Selina Abd Hamid; Nadira Kamarudin; Zaiton Selamat; Mohd Shariff Sattar; Muhamad Jalil

2005-01-01

Scanning electron microscope (SEM) is a scientific instrument that uses a beam of highly energetic electrons to examine the surface and phase distribution of specimens on a micro scale through the live imaging of secondary electrons (SE) and back-scattered electrons (BSE) images. One of the main activities of SEM Laboratory at MINT is for failure analysis on metal part and components. The capability of SEM is excellent for determining the root cause of metal failures such as ductility or brittleness, stress corrosion, fatigue and other types of failures. Most of our customers that request for failure analysis are from local petrochemical plants, manufacturers of automotive components, pipeline maintenance personnel and engineers who involved in the development of metal parts and component. This paper intends to discuss some of the technical concepts in failure analysis associated with SEM. (Author)

Failure analysis of medical Linac (LMR-15)

International Nuclear Information System (INIS)

Kato, Kiyotaka; Nakamura, Katsumi; Ogihara, Kiyoshi; Takahashi, Katsuhiko; Sato, Kazuhisa.

1994-01-01

In August 1978, Linac (LMR-15, Z4 Toshiba) was installed at our hospital and in use for 12 years up to September 1990. Recently, we completed working and failure records on this apparatus during the 12-year period, for the purpose of their analysis in the basis of reliability engineering. The results revealed operation rate of 97.85% on the average, mean time between failures (MTBF) from 40-70 hours about the beginning of its working to 280 hours for 2 years before renewal and practically satisfactory values of mean life of parts of life such as magnetron, thyratron and electron gun; the above respective values proved to be above those reported by other literature. On the other hand, we classified, by occurring system, the contents of failures in the apparatus and determined the number of failures and the temperature and humidities in case of failures to examine the correlation between the working environment and failure. The results indicated a change in humidity to gain control of failures in the dosimetric system, especially the monitoring chamber and we could back up the strength of the above correlation from a coefficient of correlation value of 0.84. (author)

Non-Invasive Ventilation in Patients with Heart Failure: A Systematic Review and Meta-Analysis

Directory of Open Access Journals (Sweden)

Hugo Souza Bittencourt

Full Text Available Abstract Non-invasive ventilation (NIV may perfect respiratory and cardiac performance in patients with heart failure (HF. The objective of the study to establish, through systematic review and meta-analysis, NIV influence on functional capacity of HF patients. A systematic review with meta-analysis of randomized studies was carried out through research of databases of Cochrane Library, SciELO, Pubmed and PEDro, using the key-words: heart failure, non-invasive ventilation, exercise tolerance; and the free terms: bi-level positive airway pressure (BIPAP, continuous positive airway pressure (CPAP, and functional capacity (terms were searched for in English and Portuguese using the Boolean operators AND and OR. Methodological quality was ensured through PEDro scale. Weighted averages and a 95% confidence interval (CI were calculated. The meta-analysis was done thorugh the software Review Manager, version 5.3 (Cochrane Collaboration. Four randomized clinical trials were included. Individual studies suggest NIV improved functional capacity. NIV resulted in improvement in the distance of the six-minute walk test (6MWT (68.7m 95%CI: 52.6 to 84.9 in comparison to the control group. We conclude that the NIV is an intervention that promotes important effects in the improvement of functional capacity of HF patients. However, there is a gap in literature on which are the most adequate parameters for the application of this technique.

Right ventricular systolic function in hypertensive heart failure

Directory of Open Access Journals (Sweden)

Oketona OA

2017-09-01

Full Text Available OA Oketona,1 MO Balogun,2 AO Akintomide,2 OE Ajayi,2 RA Adebayo,2 TO Mene-Afejuku,3 OT Oketona,1 OJ Bamikole2 1Fort Nelson General Hospital, Fort Nelson, BC, Canada; 2Cardiology Unit, Department of Medicine, Obafemi Awolowo University Teaching Hospitals Complex, Ife, Osun State, Nigeria; 3Department of Medicine, Metropolitan Hospital Center, New York, NY, USA Background: Heart failure (HF is a major cause of cardiovascular admissions and hypertensive heart failure (HHF is the most common cause of HF admissions in sub-Saharan Africa, Nigeria inclusive. Right ventricular (RV dysfunction is being increasingly recognized in HF and found to be an independent predictor of adverse outcomes in HF. This study aimed to determine the prevalence of RV systolic dysfunction in HHF by several echocardiographic parameters.Methodology: One hundred subjects with HHF were recruited consecutively into the study along with 50 age and sex-matched controls. All study participants gave written informed consent, and had a full physical examination, blood investigations, 12-lead electrocardiogram, and transthoracic echocardiography. RV systolic function was assessed in all subjects using different methods based on the American Society of Echocardiography guidelines for echocardiographic assessment of the right heart in adults. This included tricuspid annular plane systolic excursion (TAPSE, RV myocardial performance index (MPI, and RV systolic excursion velocity by tissue Doppler (S′.Results: RV systolic dysfunction was found in 53% of subjects with HHF by TAPSE, 56% by RV MPI, and 48% by tissue Doppler systolic excursion S′. RV systolic dysfunction increased with reducing left ventricular ejection fraction (LVEF in subjects with HHF.Conclusion: A high proportion of subjects with HHF were found to have RV systolic functional abnormalities using TAPSE, RV MPI, and RV S′. Prevalence of RV systolic dysfunction increased with reducing LVEF. Keywords: right ventricle

Survival analysis of heart failure patients: A case study.

Science.gov (United States)

Ahmad, Tanvir; Munir, Assia; Bhatti, Sajjad Haider; Aftab, Muhammad; Raza, Muhammad Ali

2017-01-01

This study was focused on survival analysis of heart failure patients who were admitted to Institute of Cardiology and Allied hospital Faisalabad-Pakistan during April-December (2015). All the patients were aged 40 years or above, having left ventricular systolic dysfunction, belonging to NYHA class III and IV. Cox regression was used to model mortality considering age, ejection fraction, serum creatinine, serum sodium, anemia, platelets, creatinine phosphokinase, blood pressure, gender, diabetes and smoking status as potentially contributing for mortality. Kaplan Meier plot was used to study the general pattern of survival which showed high intensity of mortality in the initial days and then a gradual increase up to the end of study. Martingale residuals were used to assess functional form of variables. Results were validated computing calibration slope and discrimination ability of model via bootstrapping. For graphical prediction of survival probability, a nomogram was constructed. Age, renal dysfunction, blood pressure, ejection fraction and anemia were found as significant risk factors for mortality among heart failure patients.

Failure analysis of the boiler water-wall tube

Directory of Open Access Journals (Sweden)

S.W. Liu

2017-10-01

Full Text Available Failure analysis of the boiler water-wall tube is presented in this work. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy were carried out. Tube wall thickness measurements were performed on the ruptured tube. The fire-facing side of the tube was observed to have experienced significant wall thinning. The composition of the matrix material of the tube meets the requirements of the relevant standards. Microscopic examinations showed that the spheroidization of pearlite is not very obvious. The failure mechanism is identified as a result of the significant localized wall thinning of the boiler water-wall tube due to oxidation.

Failure analysis of the boiler water-wall tube

OpenAIRE

S.W. Liu; W.Z. Wang; C.J. Liu

2017-01-01

Failure analysis of the boiler water-wall tube is presented in this work. In order to examine the causes of failure, various techniques including visual inspection, chemical analysis, optical microscopy, scanning electron microscopy and energy dispersive spectroscopy were carried out. Tube wall thickness measurements were performed on the ruptured tube. The fire-facing side of the tube was observed to have experienced significant wall thinning. The composition of the matrix material of the tu...

Fuzzy logic prioritization of failures in a system failure mode, effects and criticality analysis

International Nuclear Information System (INIS)

Bowles, John B.; Pelaez, C.E.

1995-01-01

This paper describes a new technique, based on fuzzy logic, for prioritizing failures for corrective actions in a Failure Mode, Effects and Criticality Analysis (FMECA). As in a traditional criticality analysis, the assessment is based on the severity, frequency of occurrence, and detectability of an item failure. However, these parameters are here represented as members of a fuzzy set, combined by matching them against rules in a rule base, evaluated with min-max inferencing, and then defuzzified to assess the riskiness of the failure. This approach resolves some of the problems in traditional methods of evaluation and it has several advantages compared to strictly numerical methods: 1) it allows the analyst to evaluate the risk associated with item failure modes directly using the linguistic terms that are employed in making the criticality assessment; 2) ambiguous, qualitative, or imprecise information, as well as quantitative data, can be used in the assessment and they are handled in a consistent manner; and 3) it gives a more flexible structure for combining the severity, occurrence, and detectability parameters. Two fuzzy logic based approaches for assessing criticality are presented. The first is based on the numerical rankings used in a conventional Risk Priority Number (RPN) calculation and uses crisp inputs gathered from the user or extracted from a reliability analysis. The second, which can be used early in the design process when less detailed information is available, allows fuzzy inputs and also illustrates the direct use of the linguistic rankings defined for the RPN calculations

Analysis of dependent failures in the ORNL precursor study

International Nuclear Information System (INIS)

Ballard, G.M.

1985-01-01

The study of dependent failures (or common cause/mode failures) in the safety assessment of potentially hazardous plant is one of the significant areas of uncertainty in performing probabilistic safety studies. One major reason for this uncertainty is that data on dependent failures is apparently not readily available in sufficient quantity to assist in the development and validation of models. The incident reports that were compiled for the ORNL study on Precursors to Severe Core Damage Accidents (NUREG/CR-2497) provide an opportunity to look at the importance of dependent failures in the most significant incidents of recent reactor operations, to look at the success of probabilistic risk assessment (PRA) methods in accounting for the contribution of dependent failures, and to look at the dependent failure incidents with the aim of identifying the most significant problem areas. In this paper an analysis has been made of the incidents compiled in NUREG/CR-2497 and events involving multiple failures which were not independent have been identified. From this analysis it is clear that dependent failures are a very significant contributor to the precursor incidents. The method of enumeration of accident frequency used in NUREG-2497 can be shown to take account of dependent failures and this may be a significant factor contributing to the apparent difference between the precursor accident frequency and typical PRA frequencies

Potential failure mode and effects analysis for the ITER NB injector

International Nuclear Information System (INIS)

Boldrin, M.; De Lorenzi, A.; Fiorentin, A.; Grando, L.; Marcuzzi, D.; Peruzzo, S.; Pomaro, N.; Rigato, W.; Serianni, G.

2009-01-01

The failure mode and effects analysis (FMEA) is a widely used analytical technique that helps in identifying and reducing the risks of failure in a system, component or process. The application of a systematic method like the FMEA was deemed necessary and adequate to support the design process of the ITER NBI (neutral beam injector). The approach adopted was to develop a FMEA at a general 'system level', focusing the study on the main functions of the system and ensuring that all the interfaces and interactions are covered among the various subsystems. The FMEA was extended to the whole NBI system taking into account the present design status. The FMEA procedure will be then applied to the detailed design phase at the component level, in particular to identify (or define) the ITER Class of Risk. Several important failure modes were evidenced, and estimates of subsystems and components reliability are now available. FMEA procedure resulted essential to identify and confirm the diagnostic systems required for protection and control, and the outcome of this analysis will represent the baseline document for the design of the NBI and NBTF integrated protection system. In the paper, rationale and background of the FMEA for ITER NBI are presented, methods employed are described and most interesting results are reported and discussed.

Reliability analysis for the creep rupture mode of failure

International Nuclear Information System (INIS)

Vaidyanathan, S.

1975-01-01

An analytical study has been carried out to relate the factors of safety employed in the design of a component to the probability of failure in the thermal creep rupture mode. The analysis considers the statistical variations in the operating temperature, stress and rupture time, and applies the life fraction damage criterion as the indicator of failure. Typical results for solution annealed type 304-stainless steel material for the temperature and stress variations expected in an LMFBR environment have been obtained. The analytical problem was solved by considering the joint distribution of the independent variables and deriving the distribution for the function associated with the probability of failure by integrating over proper regions as dictated by the deterministic design rule. This leads to a triple integral for the final probability of failure where the coefficients of variation associated with the temperature, stress and rupture time distributions can be specified by the user. The derivation is general, and can be used for time varying stress histories and the case of irradiated material where the rupture time varies with accumulated fluence. Example calculations applied to solution annealed type 304 stainless steel material have been carried out for an assumed coefficient of variation of 2% for temperature and 6% for stress. The results show that the probability of failure associated with dependent stress intensity limits specified in the ASME Boiler and Pressure Vessel Section III Code Case 1592 is less than 5x10 -8 . Rupture under thermal creep conditions is a highly complicated phenomenon. It is believed that the present study will help in quantizing the reliability to be expected with deterministic design factors of safety

Failure analysis of a repairable system: The case study of a cam-driven reciprocating pump

Science.gov (United States)

Dudenhoeffer, Donald D.

1994-09-01

This thesis supplies a statistical and economic tool for analysis of the failure characteristics of one typical piece of equipment under evaluation: a cam-driven reciprocating pump used in the submarine's distillation system. Comprehensive statistical techniques and parametric modeling are employed to identify and quantify pump failure characteristics. Specific areas of attention include: the derivation of an optimal maximum replacement interval based on costs, an evaluation of the mission reliability for the pump as a function of pump age, and a calculation of the expected times between failures. The purpose of this analysis is to evaluate current maintenance practices of time-based replacement and examine the consequences of different replacement intervals in terms of costs and mission reliability. Tradeoffs exist between cost savings and system reliability that must be fully understood prior to making any policy decisions.

Functional microimaging. A hierarchical investigation of bone failure behavior

International Nuclear Information System (INIS)

Voide, Romain; Lenthe, G.Harry van; Stauber, Martin; Schneider, Philipp; Thurner, Philipp J.; Mueller, Ralph; Wyss, Peter; Stampanoni, Marco

2008-01-01

Biomechanical testing is the gold standard to determine bone competence, and has been used extensively. Direct mechanical testing provides detailed information on overall bone mechanical and material properties, but fails in revealing local properties such as local deformations and strains and does not permit quantification of fracture progression. Therefore, we incorporated several imaging methods in our mechanical setups to get a better insight into bone deformation and failure characteristics on various levels of structural organization. Our aim was to develop an integrative approach for hierarchical investigation of bone, working at different scales of resolution ranging from the whole bone to its ultrastructure. Inbred strains of mice make useful models to study bone properties. In this study, we concentrated on C57BL/6 (B6) and in C3H/He (C3H) mice, two strains known for their differences in bone phenotype. At the macroscopic level, we used high-resolution and high-speed cameras which allowed to visualize global failure behavior and fracture initiation with high temporal resolution. This image data proved especially important when dealing with small bones such as murine femora. At the microscopic level, bone microstructure, i.e. trabecular architecture and cortical porosity, are known to influence bone strength and failure mechanisms significantly. For this reason, we developed an image-guided failure assessment technique, also referred to as functional microimaging, allowing direct time-lapsed three-dimensional visualization and computation of local displacements and strains for better quantification of fracture initiation and progression. While the resolution of conventional desktop micro-computed tomography is typically around a few micrometers, computer tomography systems based on highly brilliant synchrotron radiation X-ray sources permit to explore the sub-micrometer world. This allowed, for the first time, to uncover fully nondestructively the 3D

Failure analysis of fractured dental zirconia implants.

Science.gov (United States)

Gahlert, M; Burtscher, D; Grunert, I; Kniha, H; Steinhauser, E

2012-03-01

The purpose of the present study was the macroscopic and microscopic failure analysis of fractured zirconia dental implants. Thirteen fractured one-piece zirconia implants (Z-Look3) out of 170 inserted implants with an average in situ period of 36.75±5.34 months (range from 20 to 56 months, median 38 months) were prepared for macroscopic and microscopic (scanning electron microscopy [SEM]) failure analysis. These 170 implants were inserted in 79 patients. The patient histories were compared with fracture incidences to identify the reasons for the failure of the implants. Twelve of these fractured implants had a diameter of 3.25 mm and one implant had a diameter of 4 mm. All fractured implants were located in the anterior side of the maxilla and mandibula. The patient with the fracture of the 4 mm diameter implant was adversely affected by strong bruxism. By failure analysis (SEM), it could be demonstrated that in all cases, mechanical overloading caused the fracture of the implants. Inhomogeneities and internal defects of the ceramic material could be excluded, but notches and scratches due to sandblasting of the surface led to local stress concentrations that led to the mentioned mechanical overloading by bending loads. The present study identified a fracture rate of nearly 10% within a follow-up period of 36.75 months after prosthetic loading. Ninety-two per cent of the fractured implants were so-called diameter reduced implants (diameter 3.25 mm). These diameter reduced implants cannot be recommended for further clinical use. Improvement of the ceramic material and modification of the implant geometry has to be carried out to reduce the failure rate of small-sized ceramic implants. Nevertheless, due to the lack of appropriate laboratory testing, only clinical studies will demonstrate clearly whether and how far the failure rate can be reduced. © 2011 John Wiley & Sons A/S.

Failure mode and effects analysis: an empirical comparison of failure mode scoring procedures.

Science.gov (United States)

Ashley, Laura; Armitage, Gerry

2010-12-01

To empirically compare 2 different commonly used failure mode and effects analysis (FMEA) scoring procedures with respect to their resultant failure mode scores and prioritization: a mathematical procedure, where scores are assigned independently by FMEA team members and averaged, and a consensus procedure, where scores are agreed on by the FMEA team via discussion. A multidisciplinary team undertook a Healthcare FMEA of chemotherapy administration. This included mapping the chemotherapy process, identifying and scoring failure modes (potential errors) for each process step, and generating remedial strategies to counteract them. Failure modes were scored using both an independent mathematical procedure and a team consensus procedure. Almost three-fifths of the 30 failure modes generated were scored differently by the 2 procedures, and for just more than one-third of cases, the score discrepancy was substantial. Using the Healthcare FMEA prioritization cutoff score, almost twice as many failure modes were prioritized by the consensus procedure than by the mathematical procedure. This is the first study to empirically demonstrate that different FMEA scoring procedures can score and prioritize failure modes differently. It found considerable variability in individual team members' opinions on scores, which highlights the subjective and qualitative nature of failure mode scoring. A consensus scoring procedure may be most appropriate for FMEA as it allows variability in individuals' scores and rationales to become apparent and to be discussed and resolved by the team. It may also yield team learning and communication benefits unlikely to result from a mathematical procedure.

Failure analysis of stainless steel femur fixation plate.

Science.gov (United States)

Hussain, P B; Mohammad, M

2004-05-01

Failure analysis was performed to investigate the failure of the femur fixation plate which was previously fixed on the femur of a girl. Radiography, metallography, fractography and mechanical testing were conducted in this study. The results show that the failure was due to the formation of notches on the femur plate. These notches act as stress raisers from where the cracks start to propagate. Finally fracture occurred on the femur plate and subsequently, the plate failed.

failure analysis of a uav flight control system using markov analysis

African Journals Online (AJOL)

eobe

2016-01-01

Jan 1, 2016 ... Tree Analysis (FTA), Dependence Diagram Analysis. (DDA) and Markov Analysis (MA) are the most widely-used methods of probabilistic safety and reliability analysis for airborne system [1]. Fault trees analysis is a backward failure searching ..... [4] Christopher Dabrowski and Fern Hunt Markov Chain.

Early failure analysis of machining centers: a case study

International Nuclear Information System (INIS)

Wang Yiqiang; Jia Yazhou; Jiang Weiwei

2001-01-01

To eliminate the early failures and improve the reliability, nine ex-factory machining centers are traced under field conditions in workshops. Their early failure information throughout the ex-factory run-in test is collected. The field early failure database is constructed based on the collection of field early failure data and the codification of data. Early failure mode and effects analysis is performed to indicate the weak subsystem of a machining center or the troublemaker. The distribution of the time between early failures is analyzed and the optimal ex-factory run-in test time for machining center that may expose sufficiently the early failures and cost minimum is discussed. Suggestions how to arrange ex-factory run-in test and how to take actions to reduce early failures for machining center is proposed

Statistical analysis on failure-to-open/close probability of motor-operated valve in sodium system

International Nuclear Information System (INIS)

Kurisaka, Kenichi

1998-08-01

The objective of this work is to develop basic data for examination on efficiency of preventive maintenance and actuation test from the standpoint of failure probability. This work consists of a statistical trend analysis of valve failure probability in a failure-to-open/close mode on time since installation and time since last open/close action, based on the field data of operating- and failure-experience. In this work, the terms both dependent and independent on time were considered in the failure probability. The linear aging model was modified and applied to the first term. In this model there are two terms with both failure rates in proportion to time since installation and to time since last open/close-demand. Because of sufficient statistical population, motor-operated valves (MOV's) in sodium system were selected to be analyzed from the CORDS database which contains operating data and failure data of components in the fast reactors and sodium test facilities. According to these data, the functional parameters were statistically estimated to quantify the valve failure probability in a failure-to-open/close mode, with consideration of uncertainty. (J.P.N.)

Improvement of Myocardial Function Following Catheter-Based Renal Denervation in Heart Failure

Directory of Open Access Journals (Sweden)

Song-Yan Liao, MD

2017-06-01

Full Text Available Summary: Renal denervation (RD is a potential novel nonpharmacological therapy for heart failure (HF. We performed bilateral catheter-based RD in 10 adult pigs and compared them with 10 control subjects after induction of HF to investigate the long-term beneficial effects of RD on left ventricular (LV function and regional norepinephrine gradient after conventional HF pharmacological therapy. Compared with control subjects, animals treated with RD demonstrated an improvement in LV function and reduction of norepinephrine gradients over the myocardium and kidney at 10-week follow-up. Our results demonstrated that effective bilateral RD decrease regional norepinephrine gradients and improve LV contractile function compared with medical therapy alone. Key Words: heart failure, left ventricular function, norepinephrine, renal denervation

Failure Mode and Effects Analysis (FMEA) of the solid state full length rod control system

International Nuclear Information System (INIS)

Shopsky, W.E.

1977-01-01

The Full Length Rod Control System (FLRCS) controls the power to the rod drive mechanisms for rod movement in response to signals received from the Reactor Control System or from signals generated through Reactor Operator action. Rod movement is used to control reactivity of the reactor during plant operation. The Full Length Rod Control System is designed to perform its reactivity control function in conjunction with the Reactor Control and Protection System, to maintain the reactor core within design safety limits. By the use of a Failure Mode and Effects Analysis, it is shown that the FLRCS will perform its reactivity control functions considering the loss of single active components. That is, sufficient fault limiting control circuits are provided which blocks control rod movement and/or indicates presence of a fault condition at the Control Board. Reactor operator action or automatic reactor trip will thus mitigate the consequences of potential failure of the FLRCS. The analysis also qualitatively demonstrates the reliability of the FLRCS to perform its intended function

Reliability analysis based on the losses from failures.

Science.gov (United States)

Todinov, M T

2006-04-01

The conventional reliability analysis is based on the premise that increasing the reliability of a system will decrease the losses from failures. On the basis of counterexamples, it is demonstrated that this is valid only if all failures are associated with the same losses. In case of failures associated with different losses, a system with larger reliability is not necessarily characterized by smaller losses from failures. Consequently, a theoretical framework and models are proposed for a reliability analysis, linking reliability and the losses from failures. Equations related to the distributions of the potential losses from failure have been derived. It is argued that the classical risk equation only estimates the average value of the potential losses from failure and does not provide insight into the variability associated with the potential losses. Equations have also been derived for determining the potential and the expected losses from failures for nonrepairable and repairable systems with components arranged in series, with arbitrary life distributions. The equations are also valid for systems/components with multiple mutually exclusive failure modes. The expected losses given failure is a linear combination of the expected losses from failure associated with the separate failure modes scaled by the conditional probabilities with which the failure modes initiate failure. On this basis, an efficient method for simplifying complex reliability block diagrams has been developed. Branches of components arranged in series whose failures are mutually exclusive can be reduced to single components with equivalent hazard rate, downtime, and expected costs associated with intervention and repair. A model for estimating the expected losses from early-life failures has also been developed. For a specified time interval, the expected losses from early-life failures are a sum of the products of the expected number of failures in the specified time intervals covering the

Beyond reliability, multi-state failure analysis of satellite subsystems: A statistical approach

International Nuclear Information System (INIS)

Castet, Jean-Francois; Saleh, Joseph H.

2010-01-01

Reliability is widely recognized as a critical design attribute for space systems. In recent articles, we conducted nonparametric analyses and Weibull fits of satellite and satellite subsystems reliability for 1584 Earth-orbiting satellites launched between January 1990 and October 2008. In this paper, we extend our investigation of failures of satellites and satellite subsystems beyond the binary concept of reliability to the analysis of their anomalies and multi-state failures. In reliability analysis, the system or subsystem under study is considered to be either in an operational or failed state; multi-state failure analysis introduces 'degraded states' or partial failures, and thus provides more insights through finer resolution into the degradation behavior of an item and its progression towards complete failure. The database used for the statistical analysis in the present work identifies five states for each satellite subsystem: three degraded states, one fully operational state, and one failed state (complete failure). Because our dataset is right-censored, we calculate the nonparametric probability of transitioning between states for each satellite subsystem with the Kaplan-Meier estimator, and we derive confidence intervals for each probability of transitioning between states. We then conduct parametric Weibull fits of these probabilities using the Maximum Likelihood Estimation (MLE) approach. After validating the results, we compare the reliability versus multi-state failure analyses of three satellite subsystems: the thruster/fuel; the telemetry, tracking, and control (TTC); and the gyro/sensor/reaction wheel subsystems. The results are particularly revealing of the insights that can be gleaned from multi-state failure analysis and the deficiencies, or blind spots, of the traditional reliability analysis. In addition to the specific results provided here, which should prove particularly useful to the space industry, this work highlights the importance

Evaluation of radioimmunoassay for renal functions in senile patients with cor pulmonale without respiratory failure

International Nuclear Information System (INIS)

Fu Benqi; Chen Mingxi; Zhou Gangyi; Zhang Zhengzhong

1995-01-01

The results of RIA about serum β 2 -MG and urine β 2 -MG, Alb, IgG in the senile patients with cor pulmonale are reported. The contents of sβ 2 -MG, uβ 2 -MG, uAlb in non-respiratory failure group are higher than that of the control group. The contents of sβ 2 -MG, uβ 2 -MG, uAlb and uIgG in the respiratory failure group are higher than that of the non-respiratory failure group. The results show that the renal glamorous and renal tubules functions are slightly damaged in non-respiratory failure group, while functions of the respiratory failure group become worse

Extending Failure Modes and Effects Analysis Approach for Reliability Analysis at the Software Architecture Design Level

NARCIS (Netherlands)

Sözer, Hasan; Tekinerdogan, B.; Aksit, Mehmet; de Lemos, Rogerio; Gacek, Cristina

2007-01-01

Several reliability engineering approaches have been proposed to identify and recover from failures. A well-known and mature approach is the Failure Mode and Effect Analysis (FMEA) method that is usually utilized together with Fault Tree Analysis (FTA) to analyze and diagnose the causes of failures.

Machinery failure analysis and troubleshooting practical machinery management for process plants

CERN Document Server

Bloch, Heinz P

2012-01-01

Solve the machinery failure problems costing you time and money with this classic, comprehensive guide to analysis and troubleshooting  Provides detailed, complete and accurate information on anticipating risk of component failure and avoiding equipment downtime Includes numerous photographs of failed parts to ensure you are familiar with the visual evidence you need to recognize Covers proven approaches to failure definition and offers failure identification and analysis methods that can be applied to virtually all problem situations Demonstr

Failure mode and effect analysis: improving intensive care unit risk management processes.

Science.gov (United States)

Askari, Roohollah; Shafii, Milad; Rafiei, Sima; Abolhassani, Mohammad Sadegh; Salarikhah, Elaheh

2017-04-18

Purpose Failure modes and effects analysis (FMEA) is a practical tool to evaluate risks, discover failures in a proactive manner and propose corrective actions to reduce or eliminate potential risks. The purpose of this paper is to apply FMEA technique to examine the hazards associated with the process of service delivery in intensive care unit (ICU) of a tertiary hospital in Yazd, Iran. Design/methodology/approach This was a before-after study conducted between March 2013 and December 2014. By forming a FMEA team, all potential hazards associated with ICU services - their frequency and severity - were identified. Then risk priority number was calculated for each activity as an indicator representing high priority areas that need special attention and resource allocation. Findings Eight failure modes with highest priority scores including endotracheal tube defect, wrong placement of endotracheal tube, EVD interface, aspiration failure during suctioning, chest tube failure, tissue injury and deep vein thrombosis were selected for improvement. Findings affirmed that improvement strategies were generally satisfying and significantly decreased total failures. Practical implications Application of FMEA in ICUs proved to be effective in proactively decreasing the risk of failures and corrected the control measures up to acceptable levels in all eight areas of function. Originality/value Using a prospective risk assessment approach, such as FMEA, could be beneficial in dealing with potential failures through proposing preventive actions in a proactive manner. The method could be used as a tool for healthcare continuous quality improvement so that the method identifies both systemic and human errors, and offers practical advice to deal effectively with them.

Root cause of failure analysis and the system engineer

International Nuclear Information System (INIS)

Coppock, M.S.; Hartwig, A.W.

1990-01-01

In an industry where ever-increasing emphasis is being placed on root cause of failure determination, it is imperative that a successful nuclear utility have an effective means of identifying failures and performing the necessary analyses. The current Institute of Nuclear Power Operations (INPO) good practice, OE-907, root-cause analysis, gives references to methodology that will help determine breakdowns in procedures, programs, or design but gives very little guidance on how or when to perform component root cause of failure analyses. The system engineers of nuclear utilities are considered the focal point for their respective systems and are required by most programs to investigate component failures. The problem that the system engineer faces in determining a component root cause of failures lies in acquisition of the necessary data to identify the need to perform the analysis and in having the techniques and equipment available to perform it. The system engineers at the Palo Verde nuclear generating station routinely perform detailed component root cause of failure analyses. The Palo Verde program provides the system engineers with the information necessary to identify when a component root cause of failure is required. Palo Verde also has the necessary equipment on-site to perform the analyses

Reaction Times to Consecutive Automation Failures: A Function of Working Memory and Sustained Attention.

Science.gov (United States)

Jipp, Meike

2016-12-01

This study explored whether working memory and sustained attention influence cognitive lock-up, which is a delay in the response to consecutive automation failures. Previous research has demonstrated that the information that automation provides about failures and the time pressure that is associated with a task influence cognitive lock-up. Previous research has also demonstrated considerable variability in cognitive lock-up between participants. This is why individual differences might influence cognitive lock-up. The present study tested whether working memory-including flexibility in executive functioning-and sustained attention might be crucial in this regard. Eighty-five participants were asked to monitor automated aircraft functions. The experimental manipulation consisted of whether or not an initial automation failure was followed by a consecutive failure. Reaction times to the failures were recorded. Participants' working-memory and sustained-attention abilities were assessed with standardized tests. As expected, participants' reactions to consecutive failures were slower than their reactions to initial failures. In addition, working-memory and sustained-attention abilities enhanced the speed with which participants reacted to failures, more so with regard to consecutive than to initial failures. The findings highlight that operators with better working memory and sustained attention have small advantages when initial failures occur, but their advantages increase across consecutive failures. The results stress the need to consider personnel selection strategies to mitigate cognitive lock-up in general and training procedures to enhance the performance of low ability operators. © 2016, Human Factors and Ergonomics Society.

The effects of heart failure on renal function.

Science.gov (United States)

Udani, Suneel M; Koyner, Jay L

2010-08-01

Heart-kidney interactions have been increasingly recognized by clinicians and researchers who study and treat heart failure and kidney disease. A classification system has been developed to categorize the different manifestations of cardiac and renal dysfunction. Work has highlighted the significant negative prognostic effect of worsening renal function on outcomes for individuals with heart failure. The etiology of concomitant cardiac and renal dysfunction remains unclear; however, evidence supports alternatives to the established theory of underfilling, including effects of venous congestion and changes in intra-abdominal pressure. Conventional therapy focuses on blockade of the renin-angiotensin-aldosterone system with expanding use of direct renin and aldosterone antagonists. Novel therapeutic interventions using extracorporeal therapy and antagonists of the adenosine pathway show promise and require further investigation. 2010 Elsevier Inc. All rights reserved.

Process Equipment Failure Mode Analysis in a Chemical Industry

Directory of Open Access Journals (Sweden)

J. Nasl Seraji

2008-04-01

Full Text Available Background and aims   Prevention of potential accidents and safety promotion in chemical processes requires systematic safety management in them. The main objective of this study was analysis of important process equipment components failure modes and effects in H2S and CO2  isolation from extracted natural gas process.   Methods   This study was done in sweetening unit of an Iranian gas refinery. Failure Mode and Effect Analysis (FMEA used for identification of process equipments failures.   Results   Totally 30 failures identified and evaluated using FMEA. P-1 blower's blade breaking and sour gas pressure control valve bearing tight moving had maximum risk Priority number (RPN, P-1 body corrosion and increasing plug lower side angle of reach DEAlevel control valve  in tower - 1 were minimum calculated RPN.   Conclusion   By providing a reliable documentation system for equipment failures and  incidents recording, maintaining of basic information for later safety assessments would be  possible. Also, the probability of failures and effects could be minimized by conducting preventive maintenance.

Dissimilar weld failure analysis and development program

International Nuclear Information System (INIS)

Holko, K.H.; Li, C.C.

1982-01-01

The problem of dissimilar weld cracking and failure is examined. This problem occurs in boiler superheater and reheater sections as well as main steam piping. Typically, a dissimilar weld joins low-alloy steel tubing such as Fe-2-1/4 Cr-1Mo to stainless steel tubing such as 321H and 304H. Cracking and failure occur in the low-alloy steel heat-affected zone very close to the weld interface. The 309 stainless steel filler previously used has been replaced with nickel-base fillers such as Inconel 132, Inconel 182, and Incoweld A. This change has extended the time to cracking and failure, but has not solved the problem. To illustrate and define the problem, the metallography of damaged and failed dissimilar welds is described. Results of mechanical tests of dissimilar welds removed from service are presented, and factors believed to be influential in causing damage and failure are discussed. In addition, the importance of dissimilar weldment service history is demonstrated, and the Dissimilar Weld Failure Analysis and Development Program is described. 15 figures

Failure cause and failure rate evaluation on pumps of BWR plants in PSA. Hypothesis testing for typical or plant specific failure rate of pumps

International Nuclear Information System (INIS)

Sanada, Takahiro; Nakamura, Makoto

2009-01-01

In support of domestic nuclear industry effort to gather and analyze failure data of components concerning nuclear power plants, Nuclear Information Archives (NUCIA) are published for useful information to help PSA. This report focuses on NUCIA pertaining to pumps in domestic nuclear power plants, and provides the reliable estimation on failure rate of pumps resulting from failure cause analysis and hypothesis testing of classified and plant specific failure rate of pumps for improving quality in PSA. The classified and plant specific failure rate of pumps are estimated by analyzing individual domestic nuclear power plant's data of 26 Boiling Water Reactors (BWRs) concerning functionally structurally classified pump failures reported from beginning of commercial operation to March 31, 2007. (author)

Analysis of reactor trips involving balance-of-plant failures

International Nuclear Information System (INIS)

Seth, S.; Skinner, L.; Ettlinger, L.; Lay, R.

1986-01-01

The relatively high frequency of plant transients leading to reactor trips at nuclear power plants in the US is of economic and safety concern to the industry. A majority of such transients is due to failures in the balance-of-plant (BOP) systems. As a part of a study conducted for the US Nuclear Regulatory Commission, Mitre has carried out a further analysis of the BOP failures associated with reactor trips. The major objectives of the analysis were to examine plant-to-plant variations in BOP-related trips, to understand the causes of failures, and to determine the extent of any associated safety system challenges. The analysis was based on the Licensee Event Reports submitted on all commercial light water reactors during the 2-yr period, 1984-1985

Failure Modes and Effects Analysis on ITER DFLL-TBM system

International Nuclear Information System (INIS)

Hu Liqin; Yuan Run; Chen Hongli; Bai Yunqing

2012-01-01

As required for licensing process, accident analyses of International Thermonuclear Experimental Reactor (ITER) accounting for site specifications and design changes will be updated. Chinese Dual-Functional Lithium-Lead-Test Blanket Module (DFLL-TBM) system is a key safety-related component of ITER, its detailed safety analysis, which was designated to demonstrate the integrated technologies of both Helium single coolant (SLL) blanket and Helium-LiPb dual coolant (DLL) blanket, was performed. Failure Modes and Effects Analysis (FMEA) was applied to perform the safety analysis of DFLL-TBM. This study described the process of FMEA studies on DFLL-TBM system. All safety-related Postulated Initiating Events (PIEs) was identified. And a set of PIEs recommended to be taken into account in the further deterministic transient analyses were defined for both SLL and DLL blanket concepts separately.

Study on shielded pump system failure analysis method based on Bayesian network

International Nuclear Information System (INIS)

Bao Yilan; Huang Gaofeng; Tong Lili; Cao Xuewu

2012-01-01

This paper applies Bayesian network to the system failure analysis, with an aim to improve knowledge representation of the uncertainty logic and multi-fault states in system failure analysis. A Bayesian network for shielded pump failure analysis is presented, conducting fault parameter learning, updating Bayesian network parameter based on new samples. Finally, through the Bayesian network inference, vulnerability in this system, the largest possible failure modes, and the fault probability are obtained. The powerful ability of Bayesian network to analyze system fault is illustrated by examples. (authors)

Renal function and acute heart failure outcome.

Science.gov (United States)

Llauger, Lluís; Jacob, Javier; Miró, Òscar

2018-06-05

The interaction between acute heart failure (AHF) and renal dysfunction is complex. Several studies have evaluated the prognostic value of this syndrome. The aim of this systematic review, which includes non-selected samples, was to investigate the impact of different renal function variables on the AHF prognosis. The categories included in the studies reviewed included: creatinine, blood urea nitrogen (BUN), the BUN/creatinine quotient, chronic kidney disease, the formula to estimate the glomerular filtration rate, criteria of acute renal injury and new biomarkers of renal damage such as neutrophil gelatinase-associated lipocalin (NGAL and cystatin c). The basal alterations of the renal function, as well as the acute alterations, transient or not, are related to a worse prognosis in AHF, it is therefore necessary to always have baseline, acute and evolutive renal function parameters. Copyright © 2018 Elsevier España, S.L.U. All rights reserved.

Survival analysis of heart failure patients: A case study.

Directory of Open Access Journals (Sweden)

Tanvir Ahmad

Full Text Available This study was focused on survival analysis of heart failure patients who were admitted to Institute of Cardiology and Allied hospital Faisalabad-Pakistan during April-December (2015. All the patients were aged 40 years or above, having left ventricular systolic dysfunction, belonging to NYHA class III and IV. Cox regression was used to model mortality considering age, ejection fraction, serum creatinine, serum sodium, anemia, platelets, creatinine phosphokinase, blood pressure, gender, diabetes and smoking status as potentially contributing for mortality. Kaplan Meier plot was used to study the general pattern of survival which showed high intensity of mortality in the initial days and then a gradual increase up to the end of study. Martingale residuals were used to assess functional form of variables. Results were validated computing calibration slope and discrimination ability of model via bootstrapping. For graphical prediction of survival probability, a nomogram was constructed. Age, renal dysfunction, blood pressure, ejection fraction and anemia were found as significant risk factors for mortality among heart failure patients.

Comprehensive method of common-mode failure analysis for LMFBR safety systems

International Nuclear Information System (INIS)

Unione, A.J.; Ritzman, R.L.; Erdmann, R.C.

1976-01-01

A technique is demonstrated which allows the systematic treatment of common-mode failures of safety system performance. The technique uses log analysis in the form of fault and success trees to qualitatively assess the sources of common-mode failure and quantitatively estimate the contribution to the overall risk of system failure. The analysis is applied to the secondary control rod system of an early sized LMFBR

Challenges in Resolution for IC Failure Analysis

Science.gov (United States)

Martinez, Nick

1999-10-01

Resolution is becoming more and more of a challenge in the world of Failure Analysis in integrated circuits. This is a result of the ongoing size reduction in microelectronics. Determining the cause of a failure depends upon being able to find the responsible defect. The time it takes to locate a given defect is extremely important so that proper corrective actions can be taken. The limits of current microscopy tools are being pushed. With sub-micron feature sizes and even smaller killing defects, optical microscopes are becoming obsolete. With scanning electron microscopy (SEM), the resolution is high but the voltage involved can make these small defects transparent due to the large mean-free path of incident electrons. In this presentation, I will give an overview of the use of inspection methods in Failure Analysis and show example studies of my work as an Intern student at Texas Instruments. 1. Work at Texas Instruments, Stafford, TX, was supported by TI. 2. Work at Texas Tech University, was supported by NSF Grant DMR9705498.

A statistical analysis on failure-to open/close probability of pneumatic valve in sodium cooling systems

International Nuclear Information System (INIS)

Kurisaka, Kenichi

1999-11-01

The objective of this study is to develop fundamental data for examination on efficiency of preventive maintenance and surveillance test from the standpoint of failure probability. In this study, as a major standby component, a pneumatic valve in sodium cooling systems was selected. A statistical analysis was made about a trend of valve in sodium cooling systems was selected. A statistical analysis was made about a trend of valve failure-to-open/close (FTOC) probability depending on number of demands ('n'), time since installation ('t') and standby time since last open/close action ('T'). The analysis is based on the field data of operating- and failure-experiences stored in the Component Reliability Database and Statistical Analysis System for LMFBR's (CORDS). In the analysis, the FTOC probability ('P') was expressed as follows: P=1-exp{-C-En-F/n-λT-aT(t-T/2)-AT 2 /2}. The functional parameters, 'C', 'E', 'F', 'λ', 'a' and 'A', were estimated with the maximum likelihood estimation method. As a result, the FTOC probability is almost expressed with the failure probability being derived from the failure rate under assumption of the Poisson distribution only when valve cycle (i.e. open-close-open cycle) exceeds about 100 days. When the valve cycle is shorter than about 100 days, the FTOC probability can be adequately estimated with the parameter model proposed in this study. The results obtained from this study may make it possible to derive an adequate frequency of surveillance test for a given target of the FTOC probability. (author)

A quantitative method for Failure Mode and Effects Analysis

NARCIS (Netherlands)

Braaksma, Anne Johannes Jan; Meesters, A.J.; Klingenberg, W.; Hicks, C.

2012-01-01

Failure Mode and Effects Analysis (FMEA) is commonly used for designing maintenance routines by analysing potential failures, predicting their effect and facilitating preventive action. It is used to make decisions on operational and capital expenditure. The literature has reported that despite its

Numerical analysis oriented biaxial stress-strain relation and failure criterion of plain concrete

International Nuclear Information System (INIS)

Link, J.

1975-01-01

A biaxial stress-strain relation and failure criterion is proposed, which is applicable to structural analysis methods. The formulation of material behavior of plain concrete in biaxial stress-state was developed. A nonlinear elastic, anisotropic stress-strain relation was derived with two moduli of elasticity, E 1 , E 2 and Poisson's ratios, ν 1 , ν 2 , which depend on the prevailing biaxial stress state. The stress-strain relation is valid in the whole biaxial stress field, that means with a smooth transition between the domains of tension/tension, tension/compression and compression/compression. The stress-dependent moduli E 1 , E 2 and the Poisson's ratios ν 1 , ν 2 are approximated by polynomials, trigonometrical and exponential functions. A failure criterion was defined by approximating the test results of the biaxial ultimate concrete strength with a 7th degree polynomial, which is also valid in the whole biaxial stress domain. The definition of the state of failure is given as a function of stresses as well as strains. Initial parameters of the formulation of the biaxial material behavior are the uniaxial cylindrical strength of concrete and the initial values of Young's modulus and Poisson's ratio. A simple expansion of this formulation makes it applicable not only to normal but also to light-weight concrete. Comparison of numerically calculated stress-strain curves up to the ultimate biaxial stresses which indicate the failure criteria with those obtained from tests show a very good agreement. It is shown, that the biaxial stress-strain relation can be extended for use in cases of triaxial tension/tension/compression stress state. Numerical examples of analysis of concrete slabs show the importance of incorporation of a realistic material behavior for better safety estimations

How Do Cognitive Function and Knowledge Affect Heart Failure Self-Care?

Science.gov (United States)

Dickson, Victoria Vaughan; Lee, Christopher S.; Riegel, Barbara

2011-01-01

Despite extensive patient education, few heart failure (HF) patients master self-care. Impaired cognitive function may explain why patient education is ineffective. A concurrent triangulation mixed methods design was used to explore how knowledge and cognitive function influence HF self-care. A total of 41 adults with HF participated in interviews…

Failure mode analysis of a PCRV. Influence of some hypothesis

International Nuclear Information System (INIS)

Zimmermann, T.; Saugy, B.; Rebora, B.

1975-01-01

This paper is concerned with the most recent developments and results obtained using a mathematical model for the non-linear analysis of massive reinforced and prestressed concrete strucures developed by the IPEN at the Swiss Federal Institute of Technology, in Lausanne. The method is based on three-dimensional isoparametric finite elements. A linear solution is adapted step by step to the idealized behavior laws of the materials up to the failure of the structure. The laws proposed here for the non-linear behavior of concrete and steel have been described elsewhere but a simple extension to the time-dependent behavior is presented. A numerical algorithm for the superposition of creep deformations is also proposed, the basic creep law being supposed to satisfy a power expression. Time-dependent failure is discussed. The calculus of a PCRV of a helium cooled fast reactor is then performed and the influence of the liner on the failure mode is analyzed. The failure analysis under increasing internal pressure is run at the present time and the influence of an eventual pressure in the cracks is being investigated. The paper aims mainly to demonstrate the accuracy of a failure analysis by three-dimensional finite-elements and to compare it with a model test, in particular when complete deformation and failure tests of the materials are available. The proposed model has already been extensively tested on simple structures and has proved to be useful for the analysis of different simplifying hypotheses

Failure analysis of a Francis turbine runner

Energy Technology Data Exchange (ETDEWEB)

Frunzaverde, D; Campian, V [Research Center in Hydraulics, Automation and Heat Transfer, ' Eftimie Murgu' University of Resita P-ta Traian Vuia 1-4, RO-320085, Resita (Romania); Muntean, S [Centre of Advanced Research in Engineering Sciences, Romanian Academy - Timisoara Branch Bv. Mihai Viteazu 24, RO-300223, Timisoara (Romania); Marginean, G [University of Applied Sciences Gelsenkirchen, Neidenburger Str. 10, 45877 Gelsenkirchen (Germany); Marsavina, L [Department of Strength, ' Politehnica' University of Timisoara, Bv. Mihai Viteazu 1, RO-300222, Timisoara (Romania); Terzi, R; Serban, V, E-mail: gabriela.marginean@fh-gelsenkirchen.d, E-mail: d.frunzaverde@uem.r [Ramnicu Valcea Subsidiary, S.C. Hidroelectrica S.A., Str. Decebal 11, RO-240255, Ramnicu Valcea (Romania)

2010-08-15

The variable demand on the energy market requires great flexibility in operating hydraulic turbines. Therefore, turbines are frequently operated over an extended range of regimes. Francis turbines operating at partial load present pressure fluctuations due to the vortex rope in the draft tube cone. This phenomenon generates strong vibrations and noise that may produce failures on the mechanical elements of the machine. This paper presents the failure analysis of a broken Francis turbine runner blade. The failure appeared some months after the welding repair work realized in situ on fatigue cracks initiated near to the trailing edge at the junction with the crown, where stress concentration occurs. In order to determine the causes that led to the fracture of the runner blade, the metallographic investigations on a sample obtained from the blade is carried out. The metallographic investigations included macroscopic and microscopic examinations, both performed with light and scanning electron microscopy, as well as EDX - analyses. These investigations led to the conclusion, that the cracking of the blade was caused by fatigue, initiated by the surface unevenness of the welding seam. The failure was accelerated by the hydrogen embrittlement of the filling material, which appeared as a consequence of improper welding conditions. In addition to the metallographic investigations, numerical computations with finite element analysis are performed in order to evaluate the deformation and stress distribution on blade.

Failure analysis of a Francis turbine runner

International Nuclear Information System (INIS)

Frunzaverde, D; Campian, V; Muntean, S; Marginean, G; Marsavina, L; Terzi, R; Serban, V

2010-01-01

The variable demand on the energy market requires great flexibility in operating hydraulic turbines. Therefore, turbines are frequently operated over an extended range of regimes. Francis turbines operating at partial load present pressure fluctuations due to the vortex rope in the draft tube cone. This phenomenon generates strong vibrations and noise that may produce failures on the mechanical elements of the machine. This paper presents the failure analysis of a broken Francis turbine runner blade. The failure appeared some months after the welding repair work realized in situ on fatigue cracks initiated near to the trailing edge at the junction with the crown, where stress concentration occurs. In order to determine the causes that led to the fracture of the runner blade, the metallographic investigations on a sample obtained from the blade is carried out. The metallographic investigations included macroscopic and microscopic examinations, both performed with light and scanning electron microscopy, as well as EDX - analyses. These investigations led to the conclusion, that the cracking of the blade was caused by fatigue, initiated by the surface unevenness of the welding seam. The failure was accelerated by the hydrogen embrittlement of the filling material, which appeared as a consequence of improper welding conditions. In addition to the metallographic investigations, numerical computations with finite element analysis are performed in order to evaluate the deformation and stress distribution on blade.

TU-AB-BRD-02: Failure Modes and Effects Analysis

Energy Technology Data Exchange (ETDEWEB)

Huq, M. [University of Pittsburgh Medical Center (United States)

2015-06-15

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before a failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to

TU-AB-BRD-02: Failure Modes and Effects Analysis

International Nuclear Information System (INIS)

Huq, M.

2015-01-01

Current quality assurance and quality management guidelines provided by various professional organizations are prescriptive in nature, focusing principally on performance characteristics of planning and delivery devices. However, published analyses of events in radiation therapy show that most events are often caused by flaws in clinical processes rather than by device failures. This suggests the need for the development of a quality management program that is based on integrated approaches to process and equipment quality assurance. Industrial engineers have developed various risk assessment tools that are used to identify and eliminate potential failures from a system or a process before a failure impacts a customer. These tools include, but are not limited to, process mapping, failure modes and effects analysis, fault tree analysis. Task Group 100 of the American Association of Physicists in Medicine has developed these tools and used them to formulate an example risk-based quality management program for intensity-modulated radiotherapy. This is a prospective risk assessment approach that analyzes potential error pathways inherent in a clinical process and then ranks them according to relative risk, typically before implementation, followed by the design of a new process or modification of the existing process. Appropriate controls are then put in place to ensure that failures are less likely to occur and, if they do, they will more likely be detected before they propagate through the process, compromising treatment outcome and causing harm to the patient. Such a prospective approach forms the basis of the work of Task Group 100 that has recently been approved by the AAPM. This session will be devoted to a discussion of these tools and practical examples of how these tools can be used in a given radiotherapy clinic to develop a risk based quality management program. Learning Objectives: Learn how to design a process map for a radiotherapy process Learn how to

Universal failure model for multi-unit systems with shared functionality

International Nuclear Information System (INIS)

Volovoi, Vitali

2013-01-01

A Universal Failure Model (UFM) is proposed for complex systems that rely on a large number of entities for performing a common function. Economy of scale or other considerations may dictate the need to pool resources for common purpose, but the resulting strong coupling precludes the grouping of those components into modules. Existing system-level failure models rely on modularity for reducing modeling complexity, so the UFM will fill an important gap in constructing efficient system-level models. Conceptually, the UFM resembles cellular automata (CA) infused with realistic failure mechanisms. Components’ behavior is determined based on the balance between their strength (capacity) and their load (demand) share. If the load exceeds the components’ capacity, the component fails and its load share is distributed among its neighbors (possibly with a time delay and load losses). The strength of components can degrade with time if the load exceeds an elastic threshold. The global load (demand) carried by the system can vary over time, with the peak values providing shocks to the system (e.g., wind loads in civil structures, electricity demand, stressful activities to human bodies, or drought in an ecosystem). Unlike the models traditionally studied by CA, the focus of the presented model is on the system reliability, and specifically on the study of time-to-failure distributions, rather than steady-state patterns and average time-to-failure characteristics. In this context, the relationships between the types of failure distributions and the parameters of the failure model are discussed

Identifying novel phenotypes of acute heart failure using cluster analysis of clinical variables.

Science.gov (United States)

Horiuchi, Yu; Tanimoto, Shuzou; Latif, A H M Mahbub; Urayama, Kevin Y; Aoki, Jiro; Yahagi, Kazuyuki; Okuno, Taishi; Sato, Yu; Tanaka, Tetsu; Koseki, Keita; Komiyama, Kota; Nakajima, Hiroyoshi; Hara, Kazuhiro; Tanabe, Kengo

2018-07-01

Acute heart failure (AHF) is a heterogeneous disease caused by various cardiovascular (CV) pathophysiology and multiple non-CV comorbidities. We aimed to identify clinically important subgroups to improve our understanding of the pathophysiology of AHF and inform clinical decision-making. We evaluated detailed clinical data of 345 consecutive AHF patients using non-hierarchical cluster analysis of 77 variables, including age, sex, HF etiology, comorbidities, physical findings, laboratory data, electrocardiogram, echocardiogram and treatment during hospitalization. Cox proportional hazards regression analysis was performed to estimate the association between the clusters and clinical outcomes. Three clusters were identified. Cluster 1 (n=108) represented "vascular failure". This cluster had the highest average systolic blood pressure at admission and lung congestion with type 2 respiratory failure. Cluster 2 (n=89) represented "cardiac and renal failure". They had the lowest ejection fraction (EF) and worst renal function. Cluster 3 (n=148) comprised mostly older patients and had the highest prevalence of atrial fibrillation and preserved EF. Death or HF hospitalization within 12-month occurred in 23% of Cluster 1, 36% of Cluster 2 and 36% of Cluster 3 (p=0.034). Compared with Cluster 1, risk of death or HF hospitalization was 1.74 (95% CI, 1.03-2.95, p=0.037) for Cluster 2 and 1.82 (95% CI, 1.13-2.93, p=0.014) for Cluster 3. Cluster analysis may be effective in producing clinically relevant categories of AHF, and may suggest underlying pathophysiology and potential utility in predicting clinical outcomes. Copyright © 2018 Elsevier B.V. All rights reserved.

Simple estimation procedures for regression analysis of interval-censored failure time data under the proportional hazards model.

Science.gov (United States)

Sun, Jianguo; Feng, Yanqin; Zhao, Hui

2015-01-01

Interval-censored failure time data occur in many fields including epidemiological and medical studies as well as financial and sociological studies, and many authors have investigated their analysis (Sun, The statistical analysis of interval-censored failure time data, 2006; Zhang, Stat Modeling 9:321-343, 2009). In particular, a number of procedures have been developed for regression analysis of interval-censored data arising from the proportional hazards model (Finkelstein, Biometrics 42:845-854, 1986; Huang, Ann Stat 24:540-568, 1996; Pan, Biometrics 56:199-203, 2000). For most of these procedures, however, one drawback is that they involve estimation of both regression parameters and baseline cumulative hazard function. In this paper, we propose two simple estimation approaches that do not need estimation of the baseline cumulative hazard function. The asymptotic properties of the resulting estimates are given, and an extensive simulation study is conducted and indicates that they work well for practical situations.

Improving failure analysis efficiency by combining FTA and FMEA in a recursive manner

NARCIS (Netherlands)

Peeters, J.F.W.; Basten, R.J.I.; Tinga, Tiedo

2018-01-01

When designing a maintenance programme for a capital good, especially a new one, it is of key importance to accurately understand its failure behaviour. Failure mode and effects analysis (FMEA) and fault tree analysis (FTA) are two commonly used methods for failure analysis. FMEA is a bottom-up

Improving failure analysis efficiency by combining FTA and FMEA in a recursive manner

NARCIS (Netherlands)

Peeters, J.F.W.; Basten, R.J.I.; Tinga, T.

When designing a maintenance programme for a capital good, especially a new one, it is of key importance to accurately understand its failure behaviour. Failure mode and effects analysis (FMEA) and fault tree analysis (FTA) are two commonly used methods for failure analysis. FMEA is a bottom-up

Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis.

Science.gov (United States)

Qiu, Zhenzhen; Zheng, Kai; Zhang, Haoxiang; Feng, Ji; Wang, Lizhi; Zhou, Hao

2017-01-01

Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO 2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits.

Robustness Analysis of Real Network Topologies Under Multiple Failure Scenarios

DEFF Research Database (Denmark)

Manzano, M.; Marzo, J. L.; Calle, E.

2012-01-01

on topological characteristics. Recently approaches also consider the services supported by such networks. In this paper we carry out a robustness analysis of five real backbone telecommunication networks under defined multiple failure scenarios, taking into account the consequences of the loss of established......Nowadays the ubiquity of telecommunication networks, which underpin and fulfill key aspects of modern day living, is taken for granted. Significant large-scale failures have occurred in the last years affecting telecommunication networks. Traditionally, network robustness analysis has been focused...... connections. Results show which networks are more robust in response to a specific type of failure....

Epigenetics in formation, function, and failure of the endocrine pancreas

Directory of Open Access Journals (Sweden)

Maria L. Golson

2017-09-01

Major conclusions: The improved understanding of the epigenetic underpinnings of islet cell differentiation, function and breakdown, as well as the development of innovative tools for their manipulation, is key to islet cell biology and the discovery of novel approaches to therapies for islet cell failure.

Failure Analysis for Composition of Web Services Represented as Labeled Transition Systems

Science.gov (United States)

Nadkarni, Dinanath; Basu, Samik; Honavar, Vasant; Lutz, Robyn

The Web service composition problem involves the creation of a choreographer that provides the interaction between a set of component services to realize a goal service. Several methods have been proposed and developed to address this problem. In this paper, we consider those scenarios where the composition process may fail due to incomplete specification of goal service requirements or due to the fact that the user is unaware of the functionality provided by the existing component services. In such cases, it is desirable to have a composition algorithm that can provide feedback to the user regarding the cause of failure in the composition process. Such feedback will help guide the user to re-formulate the goal service and iterate the composition process. We propose a failure analysis technique for composition algorithms that views Web service behavior as multiple sequences of input/output events. Our technique identifies the possible cause of composition failure and suggests possible recovery options to the user. We discuss our technique using a simple e-Library Web service in the context of the MoSCoE Web service composition framework.

Analysis of dependent failures in risk assessment and reliability evaluation

International Nuclear Information System (INIS)

Fleming, K.N.; Mosleh, A.; Kelley, A.P. Jr.; Gas-Cooled Reactors Associates, La Jolla, CA)

1983-01-01

The ability to estimate the risk of potential reactor accidents is largely determined by the ability to analyze statistically dependent multiple failures. The importance of dependent failures has been indicated in recent probabilistic risk assessment (PRA) studies as well as in reports of reactor operating experiences. This article highlights the importance of several different types of dependent failures from the perspective of the risk and reliability analyst and provides references to the methods and data available for their analysis. In addition to describing the current state of the art, some recent advances, pitfalls, misconceptions, and limitations of some approaches to dependent failure analysis are addressed. A summary is included of the discourse on this subject, which is presented in the Institute of Electrical and Electronics Engineers/American Nuclear Society PRA Procedures Guide

FEAT - FAILURE ENVIRONMENT ANALYSIS TOOL (UNIX VERSION)

Science.gov (United States)

Pack, G.

1994-01-01

The Failure Environment Analysis Tool, FEAT, enables people to see and better understand the effects of failures in a system. FEAT uses digraph models to determine what will happen to a system if a set of failure events occurs and to identify the possible causes of a selected set of failures. Failures can be user-selected from either engineering schematic or digraph model graphics, and the effects or potential causes of the failures will be color highlighted on the same schematic or model graphic. As a design tool, FEAT helps design reviewers understand exactly what redundancies have been built into a system and where weaknesses need to be protected or designed out. A properly developed digraph will reflect how a system functionally degrades as failures accumulate. FEAT is also useful in operations, where it can help identify causes of failures after they occur. Finally, FEAT is valuable both in conceptual development and as a training aid, since digraphs can identify weaknesses in scenarios as well as hardware. Digraphs models for use with FEAT are generally built with the Digraph Editor, a Macintosh-based application which is distributed with FEAT. The Digraph Editor was developed specifically with the needs of FEAT users in mind and offers several time-saving features. It includes an icon toolbox of components required in a digraph model and a menu of functions for manipulating these components. It also offers FEAT users a convenient way to attach a formatted textual description to each digraph node. FEAT needs these node descriptions in order to recognize nodes and propagate failures within the digraph. FEAT users store their node descriptions in modelling tables using any word processing or spreadsheet package capable of saving data to an ASCII text file. From within the Digraph Editor they can then interactively attach a properly formatted textual description to each node in a digraph. Once descriptions are attached to them, a selected set of nodes can be

An improved method for risk evaluation in failure modes and effects analysis of CNC lathe

Science.gov (United States)

Rachieru, N.; Belu, N.; Anghel, D. C.

2015-11-01

Failure mode and effects analysis (FMEA) is one of the most popular reliability analysis tools for identifying, assessing and eliminating potential failure modes in a wide range of industries. In general, failure modes in FMEA are evaluated and ranked through the risk priority number (RPN), which is obtained by the multiplication of crisp values of the risk factors, such as the occurrence (O), severity (S), and detection (D) of each failure mode. However, the crisp RPN method has been criticized to have several deficiencies. In this paper, linguistic variables, expressed in Gaussian, trapezoidal or triangular fuzzy numbers, are used to assess the ratings and weights for the risk factors S, O and D. A new risk assessment system based on the fuzzy set theory and fuzzy rule base theory is to be applied to assess and rank risks associated to failure modes that could appear in the functioning of Turn 55 Lathe CNC. Two case studies have been shown to demonstrate the methodology thus developed. It is illustrated a parallel between the results obtained by the traditional method and fuzzy logic for determining the RPNs. The results show that the proposed approach can reduce duplicated RPN numbers and get a more accurate, reasonable risk assessment. As a result, the stability of product and process can be assured.

Ductile failure analysis of API X65 pipes with notch-type defects using a local fracture criterion

International Nuclear Information System (INIS)

Oh, Chang-Kyun; Kim, Yun-Jae; Baek, Jong-Hyun; Kim, Young-Pyo; Kim, Woo-Sik

2007-01-01

A local failure criterion for API X65 steel is applied to predict ductile failure of full-scale API X65 pipes with simulated corrosion and gouge defects under internal pressure. The local failure criterion is the stress-modified fracture strain as a function of the stress triaxiality (defined by the ratio of the hydrostatic stress to the effective stress). Based on detailed finite element (FE) analyses with the proposed local failure criterion, burst pressures of defective pipes are estimated and compared with experimental data. For pipes with simulated corrosion defects, FE analysis with the proposed local fracture criterion indicates that predicted failure takes place after the defective pipes attain maximum loads for all cases, possibly due to the fact that the material has sufficient ductility. For pipes with simulated gouge defects, on the other hand, it is found that predicted failure takes place before global instability, and the predicted burst pressures are in good agreement with experimental data, providing confidence in the present approach

Economic impact of heart failure according to the effects of kidney failure.

Science.gov (United States)

Sicras Mainar, Antoni; Navarro Artieda, Ruth; Ibáñez Nolla, Jordi

2015-01-01

To evaluate the use of health care resources and their cost according to the effects of kidney failure in heart failure patients during 2-year follow-up in a population setting. Observational retrospective study based on a review of medical records. The study included patients ≥ 45 years treated for heart failure from 2008 to 2010. The patients were divided into 2 groups according to the presence/absence of KF. Main outcome variables were comorbidity, clinical status (functional class, etiology), metabolic syndrome, costs, and new cases of cardiovascular events and kidney failure. The cost model included direct and indirect health care costs. Statistical analysis included multiple regression models. The study recruited 1600 patients (prevalence, 4.0%; mean age 72.4 years; women, 59.7%). Of these patients, 70.1% had hypertension, 47.1% had dyslipidemia, and 36.2% had diabetes mellitus. We analyzed 433 patients (27.1%) with kidney failure and 1167 (72.9%) without kidney failure. Patients with kidney failure were associated with functional class III-IV (54.1% vs 40.8%) and metabolic syndrome (65.3% vs 51.9%, P<.01). The average unit cost was €10,711.40. The corrected cost in the presence of kidney failure was €14,868.20 vs €9,364.50 (P=.001). During follow-up, 11.7% patients developed ischemic heart disease, 18.8% developed kidney failure, and 36.1% developed heart failure exacerbation. Comorbidity associated with heart failure is high. The presence of kidney failure increases the use of health resources and leads to higher costs within the National Health System. Copyright © 2014 Sociedad Española de Cardiología. Published by Elsevier Espana. All rights reserved.

Worsening renal function definition is insufficient for evaluating acute renal failure in acute heart failure.

Science.gov (United States)

Shirakabe, Akihiro; Hata, Noritake; Kobayashi, Nobuaki; Okazaki, Hirotake; Matsushita, Masato; Shibata, Yusaku; Nishigoori, Suguru; Uchiyama, Saori; Asai, Kuniya; Shimizu, Wataru

2018-06-01

Whether or not the definition of a worsening renal function (WRF) is adequate for the evaluation of acute renal failure in patients with acute heart failure is unclear. One thousand and eighty-three patients with acute heart failure were analysed. A WRF, indicated by a change in serum creatinine ≥0.3 mg/mL during the first 5 days, occurred in 360 patients while no-WRF, indicated by a change failure; n = 98). The patients were assigned to another set of four groups: no-WRF/no-AKI (n = 512), no-WRF/AKI (n = 211), WRF/no-AKI (n = 239), and WRF/AKI (n = 121). A multivariate logistic regression model found that no-WRF/AKI and WRF/AKI were independently associated with 365 day mortality (hazard ratio: 1.916; 95% confidence interval: 1.234-2.974 and hazard ratio: 3.622; 95% confidence interval: 2.332-5.624). Kaplan-Meier survival curves showed that the rate of any-cause death during 1 year was significantly poorer in the no-WRF/AKI and WRF/AKI groups than in the WRF/no-AKI and no-WRF/no-AKI groups and in Class I and Class F than in Class R and the no-AKI group. The presence of AKI on admission, especially Class I and Class F status, is associated with a poor prognosis despite the lack of a WRF within the first 5 days. The prognostic ability of AKI on admission may be superior to WRF within the first 5 days. © 2018 The Authors. ESC Heart Failure published by John Wiley & Sons Ltd on behalf of the European Society of Cardiology.

Mechanics and complications of reverse shoulder arthroplasty: morse taper failure analysis and prospective rectification

International Nuclear Information System (INIS)

Hoskin, HLD; Furie, E; Ganey, TM; Schlatterer, DR; Collins, W

2017-01-01

Since Sir John Charnley began his monumental hip arthroplasty work in 1958, clinical researchers have been incrementally improving longevity and functionality of total joint systems, although implant failure occurs on occasion. The purpose of this study is to report the fracture of the humeral tray Morse taper of a reverse total shoulder system (RTSS), which to date has not been reported with metallurgic analysis for any RTSS. There was no reported antecedent fall, motor vehicle collision, or other traumatic event prior to implant fracture in this case. Analysis was performed on the retrieved failed implant by Scanning Electron Microscopy (SEM) and Electron Dispersion Spectroscopy (EDS) in an attempt to determine the failure method, as well as to offer improvements for future implants. At the time of revision surgery all explants were retained from the left shoulder of a 61-year old male who underwent a non-complicated RTSS 4 years prior. The explants, particularly the cracked humeral tray, were processed as required for SEM and EDS. Analysis was performed on the failure sites in order to determine the chemical composition of the different parts of the implant, discover the chemical composition of the filler metal used during the electron beam welding process, and to detect any foreign elements that could suggest corrosion or other evidence of failure etiology. Gross visual inspection of all explants revealed that implant failure was a result of dissociation of the taper from the humeral tray at the weld, leaving the Morse taper embedded in the humeral stem while the tray floated freely in the patient’s shoulder. SEM further confirmed the jagged edges noted grossly at the weld fracture site, both suggesting failure due to torsional forces. EDS detected elevated levels of carbon and oxygen at the fracture site on the taper only and not on the humeral tray. In order to determine the origin of the high levels of C and O, it was considered that in titanium alloys, C

Recognition and Analysis of Corrosion Failure Mechanisms

Directory of Open Access Journals (Sweden)

Steven Suess

2006-02-01

Full Text Available Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, material evaluation, data review and conclusion procurement. In analyzing corrosion failures, one must recognize the wide range of common corrosion mechanisms. The features of any corrosion failure give strong clues as to the most likely cause of the corrosion. This article details a proven approach to properly determining the root cause of a failure, and includes pictographic illustrations of the most common corrosion mechanisms, including general corrosion, pitting, galvanic corrosion, dealloying, crevice corrosion, microbiologically-influenced corrosion (MIC, corrosion fatigue, stress corrosion cracking (SCC, intergranular corrosion, fretting, erosion corrosion and hydrogen damage.

System reliability analysis using dominant failure modes identified by selective searching technique

International Nuclear Information System (INIS)

Kim, Dong-Seok; Ok, Seung-Yong; Song, Junho; Koh, Hyun-Moo

2013-01-01

The failure of a redundant structural system is often described by innumerable system failure modes such as combinations or sequences of local failures. An efficient approach is proposed to identify dominant failure modes in the space of random variables, and then perform system reliability analysis to compute the system failure probability. To identify dominant failure modes in the decreasing order of their contributions to the system failure probability, a new simulation-based selective searching technique is developed using a genetic algorithm. The system failure probability is computed by a multi-scale matrix-based system reliability (MSR) method. Lower-scale MSR analyses evaluate the probabilities of the identified failure modes and their statistical dependence. A higher-scale MSR analysis evaluates the system failure probability based on the results of the lower-scale analyses. Three illustrative examples demonstrate the efficiency and accuracy of the approach through comparison with existing methods and Monte Carlo simulations. The results show that the proposed method skillfully identifies the dominant failure modes, including those neglected by existing approaches. The multi-scale MSR method accurately evaluates the system failure probability with statistical dependence fully considered. The decoupling between the failure mode identification and the system reliability evaluation allows for effective applications to larger structural systems

Impact of etiology on the outcomes in heart failure patients treated with cardiac resynchronization therapy: a meta-analysis.

Directory of Open Access Journals (Sweden)

Yanmei Chen

Full Text Available BACKGROUND: Cardiac resynchronization therapy (CRT has been extensively demonstrated to benefit heart failure patients, but the role of underlying heart failure etiology in the outcomes was not consistently proven. This meta-analysis aimed to determine whether efficacy and effectiveness of CRT is affected by underlying heart failure etiology. METHODS AND RESULTS: Searches of MEDLINE, EMBASE and Cochrane databases were conducted to identify RCTs and observational studies that reported clinical and functional outcomes of CRT in ischemic cardiomyopathy (ICM and non-ischemic cardiomyopathy (NICM patients. Efficacy of CRT was assessed in 7 randomized controlled trials (RCTs with 7072 patients and effectiveness of CRT was evaluated in 14 observational studies with 3463 patients In the pooled analysis of RCTs, we found that CRT decreased mortality or heart failure hospitalization by 29% in ICM patients (95% confidence interval [CI], 21% to 35%, and by 28% (95% CI, 18% to 37% in NICM patients. No significant difference was observed between the 2 etiology groups (P = 0.55. In the pooled analysis of observational studies, however, we found that ICM patients had a 54% greater risk for mortality or HF hospitalization than NICM patients (relative risk: 1.54; 95% CI: 1.30-1.83; P<0.001. Both RCTs and observational studies demonstrated that NICM patients had greater echocardiographic improvements in the left ventricular ejection fraction and end-systolic volume, as compared with ICM patients (both P<0.001. CONCLUSION: CRT might reduce mortality or heart failure hospitalization in both ICM and NICM patients similarly. The improvement of the left ventricular function and remodeling is greater in NICM patients.

Heart failure analysis dashboard for patient's remote monitoring combining multiple artificial intelligence technologies.

Science.gov (United States)

Guidi, G; Pettenati, M C; Miniati, R; Iadanza, E

2012-01-01

In this paper we describe an Heart Failure analysis Dashboard that, combined with a handy device for the automatic acquisition of a set of patient's clinical parameters, allows to support telemonitoring functions. The Dashboard's intelligent core is a Computer Decision Support System designed to assist the clinical decision of non-specialist caring personnel, and it is based on three functional parts: Diagnosis, Prognosis, and Follow-up management. Four Artificial Intelligence-based techniques are compared for providing diagnosis function: a Neural Network, a Support Vector Machine, a Classification Tree and a Fuzzy Expert System whose rules are produced by a Genetic Algorithm. State of the art algorithms are used to support a score-based prognosis function. The patient's Follow-up is used to refine the diagnosis.

Physical Exercise and Patients with Chronic Renal Failure: A Meta-Analysis

Science.gov (United States)

Qiu, Zhenzhen; Zheng, Kai; Zhang, Haoxiang; Feng, Ji; Wang, Lizhi

2017-01-01

Chronic renal failure is a severe clinical problem which has some significant socioeconomic impact worldwide and hemodialysis is an important way to maintain patients' health state, but it seems difficult to get better in short time. Considering these, the aim in our research is to update and evaluate the effects of exercise on the health of patients with chronic renal failure. The databases were used to search for the relevant studies in English or Chinese. And the association between physical exercise and health state of patients with chronic renal failure has been investigated. Random-effect model was used to compare the physical function and capacity in exercise and control groups. Exercise is helpful in ameliorating the situation of blood pressure in patients with renal failure and significantly reduces VO2 in patients with renal failure. The results of subgroup analyses show that, in the age >50, physical activity can significantly reduce blood pressure in patients with renal failure. The activity program containing warm-up, strength, and aerobic exercises has benefits in blood pressure among sick people and improves their maximal oxygen consumption level. These can help patients in physical function and aerobic capacity and may give them further benefits. PMID:28316986

Effect of obesity and being overweight on long-term mortality in congestive heart failure: influence of left ventricular systolic function

DEFF Research Database (Denmark)

Gustafsson, Finn; Kragelund, Charlotte B; Torp-Pedersen, Christian

2004-01-01

AIMS: Previous studies have suggested that a high body mass index (BMI) is associated with an improved outcome in congestive heart failure (CHF). However, the studies addressing this problem have not included enough patients with non-systolic heart failure to evaluate how left ventricular systolic...... function interacts with obesity on prognosis in CHF. The aim of this study was to evaluate how BMI influences mortality in patients hospitalized with CHF, and to address in particular whether the effect of BMI is influenced by left ventricular (LV) systolic function. METHODS AND RESULTS: Retrospective...... analysis of baseline and survival data for 4700 hospitalized CHF patients for whom BMI was available. LV systolic function, as assessed by wall motion index was available for 95% of the patients. Follow-up time ranged from 5 to 8 years. In the total population, the risk of death decreased steadily...

Impact of cognitive function on compliance with treatment in heart failure

Directory of Open Access Journals (Sweden)

Beata Jankowska-Polańska

2017-02-01

Full Text Available In heart failure (HF patients frailty syndrome and cognitive impairment (CI affect outcome by decreasing the capability for performing self-care, adhering to the prescribed treatment regimen, monitoring symptoms. The aim was to investigate whether CI affects the compliance to therapeutic regimens. Methods: 170 with HF were included. We employed the Mini Mental State Examination (MMSE, for dementia and the Revised Heart Failure Compliance Scale to assess compliance. Results: CI patients showed lower compliance in all domains: 2.8±1.0 vs 3.3±1.0 (keeping appointments, 2.8±0.9 vs. 3.4±0.9 (pharmaceutical compliance, 0.4±0.8 vs. 1.4±1.2 (regular body weight monitoring, 2.0±1.3 vs. 2.7±1.0 (reduced salt intake, 1.9±1.2vs. 2.9±1.0 (fluid intake restriction, and 0.5±0.8 vs. 1.7±1.1 (regular exercise. Multiple regression analysis showed cognitive function to be an independent predictor for regular body weight monitoring (β=1.223;p<0.001, fluid intake restriction (β=1.081;p<0.001, and regular exercise (β=1.237;p<0.001. In multivariate analysis, the stimulant variables for compliance with HF treatment were: education (β=1.124, being in a relationship (β=2.231, and lack of cognitive impairment (β=0.320; the number of hospitalizations due to HF was identified as a destimulant (β=-0.495. Conclusion: Non-compliance is a major problem in elderly with HF. The cognitive function is an independent contributor to total compliance and to compliance with non-pharmaceutical recommendations. Being in a relationship and education are independent predictors of better compliance, while the number of rehospitalizations due to HF exacerbations is an independent predictor of worse compliance. Early detection of CI may offer an opportunity for intervention and a key strategy for improving clinical outcomes in older adults with HF.

The study of Influencing Maintenance Factors on Failures of Two gypsum Kilns by Failure Modes and Effects Analysis (FMEA

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Iraj Alimohammadi

2014-06-01

Full Text Available Developing technology and using equipment in Iranian industries caused that maintenance system would be more important to use. Using proper management techniques not only increase the performance of production system but also reduce the failures and costs. The aim of this study was to determine the quality of maintenance system and the effects of its components on failures of kilns in two gypsum production companies using Failure Modes and Effects Analysis (FMEA. Furthermore the costs of failures were studied. After the study of gypsum production steps in the factories, FMEA was conducted by the determination of analysis insight, information gathering, making list of kilns’ component and filling up the FMEA’s tables. The effects of failures on production, how to fail, failure rate, failure severity, and control measures were studied. The evaluation of maintenance system was studied by a check list including questions related to system components. The costs of failures were determined by refer in accounting notebooks and interview with the head of accounting department. It was found the total qualities of maintenance system in NO.1 was more than NO.2 but because of lower quality of NO.1’s kiln design, number of failures and their costs were more. In addition it was determined that repair costs in NO.2’s kiln were about one third of NO.1’s. The low severity failures caused the most costs in comparison to the moderate and low ones. The technical characteristics of kilns were appeared to be the most important factors in reducing of failures and costs.

Failure criterion of concrete type material and punching failure analysis of thick mortar plate

International Nuclear Information System (INIS)

Ohno, T.; Kuroiwa, M.; Irobe, M.

1979-01-01

In this paper falure surface of concrete type material is proposed and its validity to structural analysis is examined. The study is an introductory part of evaluation for ultimate strength of reinforced and prestressed concrete structures in reactor technology. The failure surface is expressed in a linear form in terms of octahedral normal and shear stresses. Coefficient of the latter stress is given by a trigonometric series in threefold angle of similarity. Hence, its meridians are multilinear and traces of its deviatoric sections are smooth curves having periodicity of 2π/3 around space diagonal in principal stress space. The mathematical expression of the surface has an arbitraty number of parameters so that material test results are well reflected. To confirm the effectiveness of proposed failure criterion, experiment and numerical analysis by the finite element method on punching failure of thick mortar plate in axial symmetry are compared. In the numerical procedure yield surface of the material is assumed to exist mainly in compression region, since a brittle cleavage or elastic fracture occurs in the concrete type material under stress state with tension, while a ductile or plastic fracture occurs under compressive stress state. (orig.)

Mechanical system reliability analysis using a combination of graph theory and Boolean function

International Nuclear Information System (INIS)

Tang, J.

2001-01-01

A new method based on graph theory and Boolean function for assessing reliability of mechanical systems is proposed. The procedure for this approach consists of two parts. By using the graph theory, the formula for the reliability of a mechanical system that considers the interrelations of subsystems or components is generated. Use of the Boolean function to examine the failure interactions of two particular elements of the system, followed with demonstrations of how to incorporate such failure dependencies into the analysis of larger systems, a constructive algorithm for quantifying the genuine interconnections between the subsystems or components is provided. The combination of graph theory and Boolean function provides an effective way to evaluate the reliability of a large, complex mechanical system. A numerical example demonstrates that this method an effective approaches in system reliability analysis

Embryonic kidney function in a chronic renal failure model in rodents.

Science.gov (United States)

Fujimoto, Eisuke; Yamanaka, Shuichiro; Kurihara, Sho; Tajiri, Susumu; Izuhara, Luna; Katsuoka, Yuichi; Yokote, Shinya; Matsumoto, Kei; Kobayashi, Eiji; Okano, Hirotaka James; Chikaraishi, Tatsuya; Yokoo, Takashi

2017-08-01

Rapid advancements have been made in alternative treatments for renal diseases. Our goal for renal regeneration is to establish a kidney graft derived from human embryonic tissues. In this study, we investigated the effects of host renal failure on the structure and activity of transplanted embryonic kidney and bladder, and found that diuretics effectively induced urine production in the transplanted kidney. Uremic conditions were reproduced using a 5/6 renal infarction rat model. An embryonic kidney plus bladder (embryonic day 15) was isolated from a pregnant Lewis rat and transplanted into the para-aortic area of a 5/6 renal-infarcted Lewis rat. Following growth, the embryonic bladder was successfully anastomosed to the host ureter. We assessed graft function in terms of survival rates and found no differences between normal (n = 5) and renal failure (n = 8) groups (median survival: 70.5 vs 74.5 h; p = 0.331) in terms of survival, indicating that the grafts prolonged rat survival, even under renal failure conditions. Furosemide (n = 9) significantly increased urine volume compared with saline-treated controls (n = 7; p < 0.05), confirming that the grafts were functional. We also demonstrated the possibilities of an in vivo imaging system for determining the viability of transplanted embryonic kidney with bladder. The results of this study demonstrate that transplanted embryonic kidney and bladder can grow and function effectively, even under uremic conditions.

Functional dynamic MR imaging and pharmacokinetics of Gd-DTPA in patients with renal failure

International Nuclear Information System (INIS)

Krestin, G.P.; Neufang, K.F.R.; Friedmann, G.; Clauss, W.; Schuhmann-Giampieri, G.; Stoeckl, B.

1989-01-01

This paper reports excretion of Gd-DTPA analyzed in 20 patients with renal parenchymal disease and decreased creatinine clearance (20-80 mL/min) and compared with excretion in five patients with normal renal function. All 25 underwent a dynamic MR study that employed fast gradient-echo sequences with single images during breath holding. The time between appearance of the contrast agent in the renal cortex and signal intensity drop in the medulla was an indicator of glomerular filtration rate and correlated well with creatinine clearance values. Fractionate urine collection and serum analysis up to 120 hours showed a prolonged but complete (98%) elimination of Gd-DTPA. Renal functional parameters did not change after administration of Gd-DTPA, and no nephrotoxic effects were observed. Thus, MR imaging provides a good quantitative evaluation of the glomerular filtration rate; moreover, administration of Gd-DTPA in patients with renal failure does not impair excretory function and can therefore be safely applied in patients with reduced excretory function

Signal analysis for failure detection

International Nuclear Information System (INIS)

Parpaglione, M.C.; Perez, L.V.; Rubio, D.A.; Czibener, D.; D'Attellis, C.E.; Brudny, P.I.; Ruzzante, J.E.

1994-01-01

Several methods for analysis of acoustic emission signals are presented. They are mainly oriented to detection of changes in noisy signals and characterization of higher amplitude discrete pulses or bursts. The aim was to relate changes and events with failure, crack or wear in materials, being the final goal to obtain automatic means of detecting such changes and/or events. Performance evaluation was made using both simulated and laboratory test signals. The methods being presented are the following: 1. Application of the Hopfield Neural Network (NN) model for classifying faults in pipes and detecting wear of a bearing. 2. Application of the Kohonnen and Back Propagation Neural Network model for the same problem. 3. Application of Kalman filtering to determine time occurrence of bursts. 4. Application of a bank of Kalman filters (KF) for failure detection in pipes. 5. Study of amplitude distribution of signals for detecting changes in their shape. 6. Application of the entropy distance to measure differences between signals. (author). 10 refs, 11 figs

NDT in failure analysis - some case studies [Paper IIIA-g

International Nuclear Information System (INIS)

Raj, Baldev; Bhattacharya, D.K.; Lopez, E.C.; Jayakumar, T.

1986-01-01

The effective uses of several non-destructive techniques in failure analysis are discussed. The techniques considered are: dye penetrant testing, radiography, ultrasonic testing, hardness measurement and in-situ metallography. A few failure cases are discussed to highlight the usefulness of the techniques. (author)

Relation of Renal Function with Left Ventricular Systolic Function and NT-proBNP Level and Its Prognostic Implication in Heart Failure with Preserved versus Reduced Ejection Fraction: an analysis from the Korean Heart Failure (KorHF) Registry.

Science.gov (United States)

Park, Chan Soon; Park, Jin Joo; Oh, Il-Young; Yoon, Chang-Hwan; Choi, Dong-Ju; Park, Hyun-Ah; Kang, Seok-Min; Yoo, Byung-Su; Jeon, Eun-Seok; Kim, Jae-Joong; Cho, Myeong-Chan; Chae, Shung Chull; Ryu, Kyu-Hyung; Oh, Byung-Hee

2017-09-01

The relationship between ejection fraction (EF), N-terminal pro-brain natriuretic peptide (NT-proBNP) levels and renal function is unknown as stratified by heart failure (HF) type. We investigated their relation and the prognostic value of renal function in heart failure with preserved ejection fraction (HFpEF) vs. reduced ejection fraction (HFrEF). NT-proBNP, glomerular filtration rate (GFR), and EF were obtained in 1,932 acute heart failure (AHF) patients. HFrEF was defined as EFrenal dysfunction as GFRrenal dysfunction: 30≤GFRrenal dysfunction: GFRrenal dysfunction did not differ between HFpEF and HFrEF (49% vs. 52%, p=0.210). Patients with renal dysfunction had higher 12-month mortality in both HFpEF (7.9% vs. 15.2%, log-rank p=0.008) and HFrEF (8.6% vs. 16.8%, log-rank prenal dysfunction was an independent predictor of 12-month mortality (hazard ratio [HR], 2.08; 95% confidence interval [CI], 1.40-3.11). When stratified according to EF: the prognostic value of severe renal dysfunction was attenuated in HFpEF patients (HR, 1.46; 95% CI, 0.66-3.21) contrary to HFrEF patients (HR, 2.43; 95% CI, 1.52-3.89). In AHF patients, the prevalence of renal dysfunction did not differ between HFpEF and HFrEF patients. However, the prognostic value of renal dysfunction was attenuated in HFpEF patients.

2D-speckle tracking right ventricular strain to assess right ventricular systolic function in systolic heart failure. Analysis of the right ventricular free and posterolateral walls.

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Mouton, Stéphanie; Ridon, Héléne; Fertin, Marie; Pentiah, Anju Duva; Goémine, Céline; Petyt, Grégory; Lamblin, Nicolas; Coisne, Augustin; Foucher-Hossein, Claude; Montaigne, David; de Groote, Pascal

2017-10-15

Right ventricular (RV) systolic function is a powerful prognostic factor in patients with systolic heart failure. The accurate estimation of RV function remains difficult. The aim of the study was to determine the diagnostic accuracy of 2D-speckle tracking RV strain in patients with systolic heart failure, analyzing both free and posterolateral walls. Seventy-six patients with dilated cardiopathy (left ventricular end-diastolic volume≥75ml/m 2 ) and left ventricular ejection fraction≤45% had an analysis of the RV strain. Feasibility, reproducibility and diagnostic accuracy of RV strain were analyzed and compared to other echocardiographic parameters of RV function. RV dysfunction was defined as a RV ejection fraction≤40% measured by radionuclide angiography. RV strain feasibility was 93.9% for the free-wall and 79.8% for the posterolateral wall. RV strain reproducibility was good (intra-observer and inter-observer bias and limits of agreement of 0.16±1.2% [-2.2-2.5] and 0.84±2.4 [-5.5-3.8], respectively). Patients with left heart failure have a RV systolic dysfunction that can be unmasked by advanced echocardiographic imaging: mean RV strain was -21±5.7% in patients without RV dysfunction and -15.8±5.1% in patients with RV dysfunction (p=0.0001). Mean RV strain showed the highest diagnostic accuracy to predict depressed RVEF (area under the curve (AUC) 0.75) with moderate sensitivity (60.5%) but high specificity (87.5%) using a cutoff value of -16%. RV strain seems to be a promising and more efficient measure than previous RV echocardiographic parameters for the diagnosis of RV systolic dysfunction. Copyright © 2017 Elsevier B.V. All rights reserved.

A Big Data Analysis Approach for Rail Failure Risk Assessment.

Science.gov (United States)

Jamshidi, Ali; Faghih-Roohi, Shahrzad; Hajizadeh, Siamak; Núñez, Alfredo; Babuska, Robert; Dollevoet, Rolf; Li, Zili; De Schutter, Bart

2017-08-01

Railway infrastructure monitoring is a vital task to ensure rail transportation safety. A rail failure could result in not only a considerable impact on train delays and maintenance costs, but also on safety of passengers. In this article, the aim is to assess the risk of a rail failure by analyzing a type of rail surface defect called squats that are detected automatically among the huge number of records from video cameras. We propose an image processing approach for automatic detection of squats, especially severe types that are prone to rail breaks. We measure the visual length of the squats and use them to model the failure risk. For the assessment of the rail failure risk, we estimate the probability of rail failure based on the growth of squats. Moreover, we perform severity and crack growth analyses to consider the impact of rail traffic loads on defects in three different growth scenarios. The failure risk estimations are provided for several samples of squats with different crack growth lengths on a busy rail track of the Dutch railway network. The results illustrate the practicality and efficiency of the proposed approach. © 2017 The Authors Risk Analysis published by Wiley Periodicals, Inc. on behalf of Society for Risk Analysis.

Bone Morphogenetic Protein 9 Reduces Cardiac Fibrosis and Improves Cardiac Function in Heart Failure.

Science.gov (United States)

Morine, Kevin J; Qiao, Xiaoying; York, Sam; Natov, Peter S; Paruchuri, Vikram; Zhang, Yali; Aronovitz, Mark J; Karas, Richard H; Kapur, Navin K

2018-02-27

Background -Heart failure is a growing cause of morbidity and mortality worldwide. Transforming growth factor beta (TGF-β1) promotes cardiac fibrosis, but also activates counter-regulatory pathways that serve to regulate TGF-β1 activity in heart failure. Bone morphogenetic protein 9 (BMP9) is a member of the TGFβ family of cytokines and signals via the downstream effector protein Smad1. Endoglin is a TGFβ co-receptor that promotes TGF-β1 signaling via Smad3 and binds BMP9 with high affinity. We hypothesized that BMP9 limits cardiac fibrosis by activating Smad1 and attenuating Smad3 and further that neutralizing endoglin activity promotes BMP9 activity. Methods -We examined BMP9 expression and signaling in human cardiac fibroblasts and human subjects with heart failure. We utilized the thoracic aortic constriction (TAC) induced model of heart failure to evaluate the functional effect of BMP9 signaling on cardiac remodeling. Results -BMP9 expression is increased in the circulation and left ventricle (LV) of human subjects with heart failure and is expressed by cardiac fibroblasts. Next, we observed that BMP9 attenuates Type I collagen synthesis in human cardiac fibroblasts using recombinant human BMP9 and an siRNA approach. In BMP9 -/- mice subjected to TAC, loss of BMP9 activity promotes cardiac fibrosis, impairs LV function, and increases LV levels of phosphorylated Smad3 (pSmad3), not pSmad1. In contrast, treatment of wild-type mice subjected to TAC with recombinant BMP9 limits progression of cardiac fibrosis, improves LV function, enhances myocardial capillary density, and increases LV levels of pSmad1, not pSmad3 compared to vehicle treated controls. Since endoglin binds BMP9 with high affinity, we explored the effect of reduced endoglin activity on BMP9 activity. Neutralizing endoglin activity in human cardiac fibroblasts or in wild-type mice subjected to TAC induced heart failure limits collagen production, increases BMP9 protein levels, and increases

Failure analysis of PB-1 (EBTS Be/Cu mockup)

International Nuclear Information System (INIS)

Odegard, B.C. Jr.; Cadden, C.H.

1996-11-01

Failure analysis was done on PB-1 (series of Be tiles joined to Cu alloy) following a tile failure during a high heat flux experiment in EBTS (electron beam test system). This heat flux load simulated ambient conditions inside ITER; the Be tiles were bonded to the Cu alloy using low-temperature diffusion bonding, which is being considered for fabricating plasma facing components in ITER. Results showed differences between the EBTS failure and a failure during a room temperature tensile test. The latter occurred at the Cu-Be interface in an intermetallic phase formed by reaction of the two metals at the bonding temperature. Fracture strengths measured by these tests were over 300 MPa. The high heat flux specimens failed at the Cu-Cu diffusion bond. Fracture morphology in both cases was a mixed mode of dimple rupture and transgranular cleavage. Several explanations for this difference in failure mechanism are suggested

Structural and functional changes of the heart in patients with chronic ischemic heart failure, associated with renal dysfunction

Directory of Open Access Journals (Sweden)

D. A. Lashkul

2014-04-01

. Descriptive statistics are presented as mean±standard deviation for continuous variables and as percentages for categorical variables. Depending on the distribution of the analyzed parameters used unpaired Student's t-test or U-Mann-Whitney test. Comparisons among all groups for baseline clinical variables were performed with the Pearson χ2 or Fisher exact test for categorical variables. Differences considered reliable for values of p<0,05. Results. In patients with ischemic CHF as far as reduction of GFR, an increase in left atrial diameter (p=0.006, end-diastolic size (p=0.03, end-systolic size (p=0.003 end-diastolic (p=0.03 and end-systolic volumes (p=0.02. Analysis of ejection fraction showed a significant reduction in the progression of renal dysfunction: from 55,1±14,5% in GFR over 90 ml/min/1,73m2 to 46,3±14,6% with a GFR less than 60 ml/min/1.73 m2. LV hypertrophy was registered in 63 (87.5% with normal renal function, in 202 (92.7% with mild dysfunction and in 42 (97.7% patients with moderate renal dysfunction. In the analysis of LV remodeling in patients with heart failure and normal renal function revealed the prevalence of concentric hypertrophy - in 45.8%. In mild decrease GFR stored value for concentric hypertrophy in 50% of cases. However, at lower eGFR less than 60 ml/min/1,73m2 dominated eccentric hypertrophy - in 55.8%, concentric hypertrophy in 41.9% and no patient with normal geometry. After analyzing the distribution of patients by type of violation diastolic function in patients with ischemic CHF, depending on the level of GFR, we can conclude that in normal renal function in 48.6% reported pseudonormal type, 36.1% - a abnormal of relaxation, 4.2% - restrictive type. In patients with mild to moderate decrease in GFR revealed a gradual deterioration in diastolic function as increase the proportion of more serious disorders: pseudonormal (56.9% and 60.5%, respectively and restrictive type (3.7% and 9.3%, respectively. Conclusion. In patients with

Sequentially linear analysis for simulating brittle failure

NARCIS (Netherlands)

van de Graaf, A.V.

2017-01-01

The numerical simulation of brittle failure at structural level with nonlinear finite
element analysis (NLFEA) remains a challenge due to robustness issues. We attribute these problems to the dimensions of real-world structures combined with softening behavior and negative tangent stiffness at

Effects of Statin Treatment on Inflammation and Cardiac Function in Heart Failure: An Adjusted Indirect Comparison Meta-Analysis of Randomized Trials.

Science.gov (United States)

Bonsu, Kwadwo Osei; Reidpath, Daniel Diamond; Kadirvelu, Amudha

2015-12-01

Statins are known to prevent heart failure (HF). However, it is unclear whether statins as class or type (lipophilic or hydrophilic) improve outcomes of established HF. The current meta-analysis was performed to compare the treatment effects of lipophilic and hydrophilic statins on inflammation and cardiac function in HF. Outcomes were indicators of cardiac function [changes in left ventricular ejection fraction (LVEF) and B-type natriuretic peptide (BNP)] and inflammation [changes in highly sensitive C-reactive protein (hsCRP) and interluekin-6 (IL-6)]. We conducted a search of PubMed, EMBASE, and the Cochrane databases until December 31, 2014 for randomized control trials (RCTs) of statin versus placebo in patients with HF. RCTs with their respective extracted information were dichotomized into statin type evaluated and analyzed separately. Outcomes were pooled with random effect approach, producing standardized mean differences (SMD) for each statin type. Using these pooled estimates, we performed adjusted indirect comparisons for each outcome. Data from 6214 patients from 19 trials were analyzed. Lipophilic statin was superior to hydrophilic statin treatment regarding follow-up LVEF (SMD, 4.54; 95% CI, 4.16-4.91; P statin produces greater treatment effects on cardiac function and inflammation compared with hydrophilic statin in patients with HF. Until data from adequately powered head-to-head trial of the statin types are available, our meta-analysis brings clinicians and researchers a step closer to the quest on which statin--lipophilic or hydrophilic--is associated with better outcomes in HF. © 2015 John Wiley & Sons Ltd.

Containment failure modes preliminary analysis for Atucha-I nuclear power plant during severe accidents

International Nuclear Information System (INIS)

Baron, J.; Caballero, C.; Zarate, S.M.

1997-01-01

The present work has the objective to analyze the containment behavior of the Atucha-I nuclear power plant during a severe accident, as part of a probabilistic safety assessment (PSA). Initially, a generic description of the containment failure modes considered in other PSAs is performed. Then, the possible containment failure modes for Atucha I are qualitatively analyzed, according to it design peculiarities. These failure modes involve some substantial differences from other PSAs, due to the particular design of Atucha I. Among others, it is studied the influence of: moderator/coolant separation, existence of cooling Zircaloy channels, existence of filling bodies inside the pressure vessel, reactor cavity geometry, on-line refueling mode, and existence of a double shell containment (steel and concrete) with an annular separation room. As a functions of the before mentioning analysis, a series of parameters to be taken into account is defined, on a preliminary basis, for definition of the plant damage states. (author) [es

Failure Mode and Effects Analysis (FMEA) of the Emergency Core Cooling System (ECCS) for a Westinghouse type 312, three loop pressurized water reactor

International Nuclear Information System (INIS)

Shopsky, W.E.

1977-01-01

The Emergency Core Cooling System (ECCS) is a Safeguards System designed to cool the core in the unlikely event of a Loss-of-Coolant Accident (LOCA) in the primary reactor coolant system as well as to provide additional shutdown capability following a steam break accident. The system is designed for a high reliability of providing emergency coolant and shutdown reactivity to the core for all anticipated occurrences of such accidents. The ECCS by performing its intended function assures that fuel and clad damage is minimized during accident conditions thus reducing release of fission products from the fuel. The ECCS is designed to perform its function despite sustaining a single failure by the judicious use of equipment and flow path redundancy within and outside the containment structure. By the use of an analytic tool, a Failure Mode and Effects Analysis (FMEA), it is shown that the ECCS is in compliance with the Single Failure Criterion established for active failures of fluid systems during short and long term cooling of the reactor core following a LOCA or steam break accident. An analysis was also performed with regards to passive failure of ECCS components during long-term cooling of the core following an accident. The design of the ECCS was verified as being able to tolerate a single passive failure during long-term cooling of the reactor core following an accident. The FMEA conducted qualitatively demonstrates the reliability of the ECCS (concerning active components) to perform its intended safety function

Lower head failure analysis

International Nuclear Information System (INIS)

Rempe, J.L.; Thinnes, G.L.; Allison, C.M.; Cronenberg, A.W.

1991-01-01

The US Nuclear Regulatory Commission is sponsoring a lower vessel head research program to investigate plausible modes of reactor vessel failure in order to determine (a) which modes have the greatest likelihood of occurrence during a severe accident and (b) the range of core debris and accident conditions that lead to these failures. This paper presents the methodology and preliminary results of an investigation of reactor designs and thermodynamic conditions using analytic closed-form approximations to assess the important governing parameters in non-dimensional form. Preliminary results illustrate the importance of vessel and tube geometrical parameters, material properties, and external boundary conditions on predicting vessel failure. Thermal analyses indicate that steady-state temperature distributions will occur in the vessel within several hours, although the exact time is dependent upon vessel thickness. In-vessel tube failure is governed by the tube-to-debris mass ratio within the lower head, where most penetrations are predicted to fail if surrounded by molten debris. Melt penetration distance is dependent upon the effective flow diameter of the tube. Molten debris is predicted to penetrate through tubes with a larger effective flow diameter, such as a boiling water reactor (BWR) drain nozzle. Ex-vessel tube failure for depressurized reactor vessels is predicted to be more likely for a BWR drain nozzle penetration because of its larger effective diameter. At high pressures (between ∼0.1 MPa and ∼12 MPa) ex-vessel tube rupture becomes a dominant failure mechanism, although tube ejection dominates control rod guide tube failure at lower temperatures. However, tube ejection and tube rupture predictions are sensitive to the vessel and tube radial gap size and material coefficients of thermal expansion

Sildenafil Improves Erectile Function in Men with Chronic Heart Failure

Directory of Open Access Journals (Sweden)

Niloufar Samiei

2015-06-01

Full Text Available Background: Patients with Chronic Heart Failure (CHF have been shown to have enhanced risk of Erectile Dysfunction (ED due to low cardiac output, endothelial dysfunction, medications, co-morbid conditions, and psychogenic factors. Objectives: The present study aimed to evaluate the effects of sildenafil on erectile function of patients with stable CHF using the abridged 5-item version of the International Index of Erectile Function (IIEF-5. Patients and Methods: Using convenience sampling, 222 sexually-active adult males with NYHA class I-III stable CHF were included in this cross-sectional study. All the patients filled out the IIEF-5 questionnaire, in which they were required to score the five domains of male sexual function, including erectile function, orgasm function, sexual desire, intercourse satisfaction, and overall satisfaction. All the analyses were performed using the SPSS statistical software (v. 19 and P < 0.05 was considered as statistically significant. Results: In our sample, the patients’ mean age was 47.14 ± 11.86 years, their mean left ventricular ejection fraction was 20% (15% - 25%, and the prevalence of ED was 70.3%. In addition, severe, moderate, mild to moderate, and mild ED were seen in 57%, 17%, 7%, and 19% of the patients with ED, respectively. ED was significantly more prevalent in the patients with ischemic heart failure compared to those with idiopathic dilated cardiomyopathy (84.68% vs. 55.85%, P < 0.001. Moreover, the prevalence of ED was significantly lower in the patients taking sildenafil compared to the other group (42.85% vs. 82.89%, P < 0.001. Conclusions: Sildenafil appears to provide satisfactory results toward improving sexual function in patients with CHF.

Failure analysis of buried tanks

International Nuclear Information System (INIS)

Watkins, R.K.

1994-01-01

Failure of a buried tank can be hazardous. Failure may be a leak through which product is lost from the tank; but also through which contamination can occur. Failures are epidemic -- because buried tanks are out of sight, but also because designers of buried tanks have adopted analyses developed for pressure tanks. So why do pressure tanks fail when they are buried? Most failures of buried tanks are really soil failures. Soil compresses, or slips, or liquefies. Soil is not only a load, it is a support without which the tank deforms. A high water table adds to the load on the tank. It also reduces the strength of the soil. Based on tests, structural analyses are proposed for empty tanks buried in soils of various quality, with the water table at various levels, and with internal vacuum. Failure may be collapse tank. Such collapse is a sudden, audible inversion of the cylinder when the sidefill soil slips. Failure may be flotation. Failure may be a leak. Most leaks are fractures in the welds in overlap seams at flat spots. Flat spots are caused by a hard bedding or a heavy surface wheel load. Because the tank wall is double thick at the overlap, shearing stress in the weld is increased. Other weld failures occur when an end plate shears down past a cylinder; or when the tank is supported only at its ends like a beam. These, and other, failures can be analyzed with justifiable accuracy using basic principles of mechanics of materials. 10 figs

Influence of reinforcement's corrosion into hyperstatic reinforced concrete beams: a probabilistic failure scenarios analysis

Directory of Open Access Journals (Sweden)

G. P. PELLIZZER

Full Text Available AbstractThis work aims to study the mechanical effects of reinforcement's corrosion in hyperstatic reinforced concrete beams. The focus is the probabilistic determination of individual failure scenarios change as well as global failure change along time. The limit state functions assumed describe analytically bending and shear resistance of reinforced concrete rectangular cross sections as a function of steel and concrete resistance and section dimensions. It was incorporated empirical laws that penalize the steel yield stress and the reinforcement's area along time in addition to Fick's law, which models the chloride penetration into concrete pores. The reliability theory was applied based on Monte Carlo simulation method, which assesses each individual probability of failure. The probability of global structural failure was determined based in the concept of failure tree. The results of a hyperstatic reinforced concrete beam showed that reinforcements corrosion make change into the failure scenarios modes. Therefore, unimportant failure modes in design phase become important after corrosion start.

Reliability test and failure analysis of high power LED packages

International Nuclear Information System (INIS)

Chen Zhaohui; Zhang Qin; Wang Kai; Luo Xiaobing; Liu Sheng

2011-01-01

A new type application specific light emitting diode (LED) package (ASLP) with freeform polycarbonate lens for street lighting is developed, whose manufacturing processes are compatible with a typical LED packaging process. The reliability test methods and failure criterions from different vendors are reviewed and compared. It is found that test methods and failure criterions are quite different. The rapid reliability assessment standards are urgently needed for the LED industry. 85 0 C/85 RH with 700 mA is used to test our LED modules with three other vendors for 1000 h, showing no visible degradation in optical performance for our modules, with two other vendors showing significant degradation. Some failure analysis methods such as C-SAM, Nano X-ray CT and optical microscope are used for LED packages. Some failure mechanisms such as delaminations and cracks are detected in the LED packages after the accelerated reliability testing. The finite element simulation method is helpful for the failure analysis and design of the reliability of the LED packaging. One example is used to show one currently used module in industry is vulnerable and may not easily pass the harsh thermal cycle testing. (semiconductor devices)

Statistical analysis of nuclear power plant pump failure rate variability: some preliminary results

International Nuclear Information System (INIS)

Martz, H.F.; Whiteman, D.E.

1984-02-01

In-Plant Reliability Data System (IPRDS) pump failure data on over 60 selected pumps in four nuclear power plants are statistically analyzed using the Failure Rate Analysis Code (FRAC). A major purpose of the analysis is to determine which environmental, system, and operating factors adequately explain the variability in the failure data. Catastrophic, degraded, and incipient failure severity categories are considered for both demand-related and time-dependent failures. For catastrophic demand-related pump failures, the variability is explained by the following factors listed in their order of importance: system application, pump driver, operating mode, reactor type, pump type, and unidentified plant-specific influences. Quantitative failure rate adjustments are provided for the effects of these factors. In the case of catastrophic time-dependent pump failures, the failure rate variability is explained by three factors: reactor type, pump driver, and unidentified plant-specific influences. Finally, point and confidence interval failure rate estimates are provided for each selected pump by considering the influential factors. Both types of estimates represent an improvement over the estimates computed exclusively from the data on each pump

Analysis of grouped data from field-failure reporting systems

International Nuclear Information System (INIS)

Coit, David W.; Dey, Kieron A.

1999-01-01

Observed reliability data from fielded systems is highly desirable because they implicitly account for all actual usage and environmental stresses. Many companies and large organizations have instituted automated field-failure reporting systems to organize and disseminate these data. Despite these advantages, field data must be used with caution because they often lack sufficient detail. Specifically, the precise times-to-failure are often not recorded and only cumulative failure quantities and operating times are available. When only data of this type are available, it is difficult to determine whether component or system hazard function varies with time or is constant (i.e., exponential distribution). Analysts often use the exponential distribution to model time-to-failure because the distribution parameter can be estimated with just the merged data. However, this can be dangerous if the exponential distribution is not appropriate. An approach is presented in this paper for Type II censored data, with and without replacement, to evaluate this assumption even when individual times-to-failure are not available. A hypothesis test is presented to test the suitability of the exponential distribution for a particular data set composed of multiple merged data records. Two examples are presented to demonstrate the approach. The hypothesis test readily rejects an exponential distribution assumption when the data originate from a Weibull distribution. This is a very important result because it has generally been assumed that time-to-failure data were always required to evaluate the suitability of specific time-to-failure distributions

Progressive Damage and Failure Analysis of Composite Laminates

Science.gov (United States)

Joseph, Ashith P. K.

Composite materials are widely used in various industries for making structural parts due to higher strength to weight ratio, better fatigue life, corrosion resistance and material property tailorability. To fully exploit the capability of composites, it is required to know the load carrying capacity of the parts made of them. Unlike metals, composites are orthotropic in nature and fails in a complex manner under various loading conditions which makes it a hard problem to analyze. Lack of reliable and efficient failure analysis tools for composites have led industries to rely more on coupon and component level testing to estimate the design space. Due to the complex failure mechanisms, composite materials require a very large number of coupon level tests to fully characterize the behavior. This makes the entire testing process very time consuming and costly. The alternative is to use virtual testing tools which can predict the complex failure mechanisms accurately. This reduces the cost only to it's associated computational expenses making significant savings. Some of the most desired features in a virtual testing tool are - (1) Accurate representation of failure mechanism: Failure progression predicted by the virtual tool must be same as those observed in experiments. A tool has to be assessed based on the mechanisms it can capture. (2) Computational efficiency: The greatest advantages of a virtual tools are the savings in time and money and hence computational efficiency is one of the most needed features. (3) Applicability to a wide range of problems: Structural parts are subjected to a variety of loading conditions including static, dynamic and fatigue conditions. A good virtual testing tool should be able to make good predictions for all these different loading conditions. The aim of this PhD thesis is to develop a computational tool which can model the progressive failure of composite laminates under different quasi-static loading conditions. The analysis

Iron Status in Chronic Heart Failure: Impact on Symptoms, Functional Class and Submaximal Exercise Capacity.

Science.gov (United States)

Enjuanes, Cristina; Bruguera, Jordi; Grau, María; Cladellas, Mercé; Gonzalez, Gina; Meroño, Oona; Moliner-Borja, Pedro; Verdú, José M; Farré, Nuria; Comín-Colet, Josep

2016-03-01

To evaluate the effect of iron deficiency and anemia on submaximal exercise capacity in patients with chronic heart failure. We undertook a single-center cross-sectional study in a group of stable patients with chronic heart failure. At recruitment, patients provided baseline information and completed a 6-minute walk test to evaluate submaximal exercise capacity and exercise-induced symptoms. At the same time, blood samples were taken for serological evaluation. Iron deficiency was defined as ferritin < 100 ng/mL or transferrin saturation < 20% when ferritin is < 800 ng/mL. Additional markers of iron status were also measured. A total of 538 heart failure patients were eligible for inclusion, with an average age of 71 years and 33% were in New York Heart Association class III/IV. The mean distance walked in the test was 285 ± 101 meters among those with impaired iron status, vs 322 ± 113 meters (P=.002). Symptoms during the test were more frequent in iron deficiency patients (35% vs 27%; P=.028) and the most common symptom reported was fatigue. Multivariate logistic regression analyses showed that increased levels of soluble transferrin receptor indicating abnormal iron status were independently associated with advanced New York Heart Association class (P < .05). Multivariable analysis using generalized additive models, soluble transferrin receptor and ferritin index, both biomarkers measuring iron status, showed a significant, independent and linear association with submaximal exercise capacity (P=.03 for both). In contrast, hemoglobin levels were not significantly associated with 6-minute walk test distance in the multivariable analysis. In patients with chronic heart failure, iron deficiency but not anemia was associated with impaired submaximal exercise capacity and symptomatic functional limitation. Copyright © 2015 Sociedad Española de Cardiología. Published by Elsevier España, S.L.U. All rights reserved.

Dependency Analysis Guidance Nordic/German Working Group on Common Cause Failure analysis. Phase 2, Development of Harmonized Approach and Applications for Common Cause Failure Quantification

Energy Technology Data Exchange (ETDEWEB)

Becker, Guenter; Johanson, Gunnar; Lindberg, Sandra; Vaurio, Jussi

2009-03-15

The Regulatory Code SSMFS 2008:1 of Swedish Radiation Safety Authority (SSM) includes requirements regarding the performance of probabilistic safety assessments (PSA), as well as PSA activities in general. Therefore, the follow-up of these activities is part of the inspection tasks of SSM. According to the SSMFS 2008:1, the safety analyses shall be based on a systematic identification and evaluation of such events, event sequences and other conditions which may lead to a radiological accident. The research report Nordic/German Working Group on Common cause Failure analysis. Phase 2 project report: Development of Harmonized Approach and Applications for Common Cause Failure Quantification has been developed under a contract with the Nordic PSA Group (NPSAG) and its German counterpart VGB, with the aim to create a common experience base for defence and analysis of dependent failures i.e. Common Cause Failures CCF. Phase 2 in this project if a deepened data analyses of CCF events and a demonstration on how the so called impact vectors can be constructed and on how CCF parameters are estimated. The word Guidance in the report title is used in order to indicate a common methodological guidance accepted by the NPSAG, based on current state of the art concerning the analysis of dependent failures and adapted to conditions relevant for Nordic sites. This will make it possible for the utilities to perform cost effective improvements and analyses. The report presents a common attempt by the authorities and the utilities to create a methodology and experience base for defence and analysis of dependent failures. The performed benchmark application has shown how important the interpretation of base data is to obtain robust CCF data and data analyses results. Good features were found in all benchmark approaches. The obtained experiences and approaches should now be used in harmonised procedures. A next step could be to develop and agree on event and formula driven impact vector

Dependency Analysis Guidance Nordic/German Working Group on Common Cause Failure analysis. Phase 2, Development of Harmonized Approach and Applications for Common Cause Failure Quantification

International Nuclear Information System (INIS)

Becker, Guenter; Johanson, Gunnar; Lindberg, Sandra; Vaurio, Jussi

2009-03-01

The Regulatory Code SSMFS 2008:1 of Swedish Radiation Safety Authority (SSM) includes requirements regarding the performance of probabilistic safety assessments (PSA), as well as PSA activities in general. Therefore, the follow-up of these activities is part of the inspection tasks of SSM. According to the SSMFS 2008:1, the safety analyses shall be based on a systematic identification and evaluation of such events, event sequences and other conditions which may lead to a radiological accident. The research report Nordic/German Working Group on Common cause Failure analysis. Phase 2 project report: Development of Harmonized Approach and Applications for Common Cause Failure Quantification has been developed under a contract with the Nordic PSA Group (NPSAG) and its German counterpart VGB, with the aim to create a common experience base for defence and analysis of dependent failures i.e. Common Cause Failures CCF. Phase 2 in this project if a deepened data analyses of CCF events and a demonstration on how the so called impact vectors can be constructed and on how CCF parameters are estimated. The word Guidance in the report title is used in order to indicate a common methodological guidance accepted by the NPSAG, based on current state of the art concerning the analysis of dependent failures and adapted to conditions relevant for Nordic sites. This will make it possible for the utilities to perform cost effective improvements and analyses. The report presents a common attempt by the authorities and the utilities to create a methodology and experience base for defence and analysis of dependent failures. The performed benchmark application has shown how important the interpretation of base data is to obtain robust CCF data and data analyses results. Good features were found in all benchmark approaches. The obtained experiences and approaches should now be used in harmonised procedures. A next step could be to develop and agree on event and formula driven impact vector

Failure analysis of the cement mantle in total hip arthroplasty with an efficient probabilistic method.

Science.gov (United States)

Kaymaz, Irfan; Bayrak, Ozgu; Karsan, Orhan; Celik, Ayhan; Alsaran, Akgun

2014-04-01

Accurate prediction of long-term behaviour of cemented hip implants is very important not only for patient comfort but also for elimination of any revision operation due to failure of implants. Therefore, a more realistic computer model was generated and then used for both deterministic and probabilistic analyses of the hip implant in this study. The deterministic failure analysis was carried out for the most common failure states of the cement mantle. On the other hand, most of the design parameters of the cemented hip are inherently uncertain quantities. Therefore, the probabilistic failure analysis was also carried out considering the fatigue failure of the cement mantle since it is the most critical failure state. However, the probabilistic analysis generally requires large amount of time; thus, a response surface method proposed in this study was used to reduce the computation time for the analysis of the cemented hip implant. The results demonstrate that using an efficient probabilistic approach can significantly reduce the computation time for the failure probability of the cement from several hours to minutes. The results also show that even the deterministic failure analyses do not indicate any failure of the cement mantle with high safety factors, the probabilistic analysis predicts the failure probability of the cement mantle as 8%, which must be considered during the evaluation of the success of the cemented hip implants.

Reliability analysis of software based safety functions

International Nuclear Information System (INIS)

Pulkkinen, U.

1993-05-01

The methods applicable in the reliability analysis of software based safety functions are described in the report. Although the safety functions also include other components, the main emphasis in the report is on the reliability analysis of software. The check list type qualitative reliability analysis methods, such as failure mode and effects analysis (FMEA), are described, as well as the software fault tree analysis. The safety analysis based on the Petri nets is discussed. The most essential concepts and models of quantitative software reliability analysis are described. The most common software metrics and their combined use with software reliability models are discussed. The application of software reliability models in PSA is evaluated; it is observed that the recent software reliability models do not produce the estimates needed in PSA directly. As a result from the study some recommendations and conclusions are drawn. The need of formal methods in the analysis and development of software based systems, the applicability of qualitative reliability engineering methods in connection to PSA and the need to make more precise the requirements for software based systems and their analyses in the regulatory guides should be mentioned. (orig.). (46 refs., 13 figs., 1 tab.)

Tests and analysis on steam generator tube failure propagation

International Nuclear Information System (INIS)

Tanabe, Hiromi

1990-01-01

The understanding of leak enlargement and failure propagation behavior is essential to select a design basis leak (DBL) of LMFBR steam generators. Therefore, various series of experiments, such as self-enlargement tests, target wastage tests, failure propagation tests were conducted in a wide range of leak using test facilities of SWAT at PNC/OEC. Especially, in the large leak tests, potential of overheating failure was investigated under a prototypical steam cooling condition inside target tubes. In the small leak, the difference of wastage resistivity was clarified among several tube materials such as 9-chrome steels. In regard to an analytical approach, a computer code LEAP (Leak Enlargement and Propagation) was developed on the basis of all of these experimental results. The code was used to validate the previously selected DBL of the prototype reactor, Monju, steam generator. This approach proved to be successful in spite of somewhat over-conservatism in the analysis. Moreover, LEAP clarified the effectiveness of a rapid steam dump and an enhanced leak detection system. The code improvement toward a realistic analysis is desired, however, to lessen the DBL for a future large plant and then the re-evaluation of the experimental data such as the size of secondary failure is under way. (author). 4 refs, 8 figs, 1 tab

Failure analysis of high strength pipeline with single and multiple corrosions

International Nuclear Information System (INIS)

Chen, Yanfei; Zhang, Hong; Zhang, Juan; Li, Xin; Zhou, Jing

2015-01-01

Highlights: • We study failure of high strength pipelines with single corrosion. • We give regression equations for failure pressure prediction. • We propose assessment procedure for pipelines with multiple corrosions. - Abstract: Corrosion will compromise safety operation of oil and gas pipelines, accurate determination of failure pressure finds importance in residual strength assessment and corrosion allowance design of onshore and offshore pipelines. This paper investigates failure pressure of high strength pipeline with single and multiple corrosions using nonlinear finite element analysis. On the basis of developed regression equations for failure pressure prediction of high strength pipeline with single corrosion, the paper proposes an assessment procedure for predicting failure pressure of high strength pipeline with multiple corrosions. Furthermore, failure pressures predicted by proposed solutions are compared with experimental results and various assessment methods available in literature, where accuracy and versatility are demonstrated

Therapeutic potential of functional selectivity in the treatment of heart failure

DEFF Research Database (Denmark)

Christensen, Gitte Lund; Aplin, Mark; Hansen, Jakob Lerche

2010-01-01

Adrenergic and angiotensin receptors are prominent targets in pharmacological alleviation of cardiac remodeling and heart failure, but their use is associated with cardiodepressant side effects. Recent advances in our understanding of seven transmembrane receptor signaling show that it is possible...... to design ligands with "functional selectivity," acting as agonists on certain signaling pathways while antagonizing others. This represents a major pharmaceutical opportunity to separate desired from adverse effects governed by the same receptor. Accordingly, functionally selective ligands are currently...

Failure analysis on a chemical waste pipe

International Nuclear Information System (INIS)

Ambler, J.R.

1985-01-01

A failure analysis of a chemical waste pipe illustrates how nuclear technology can spin off metallurgical consultant services. The pipe, made of zirconium alloy (Zr-2.5 wt percent Nb, UNS 60705), had cracked in several places, all at butt welds. A combination of fractography and metallography indicated delayed hydride cracking

Molecular Adsorbent Recirculating System Can Reduce Short-Term Mortality Among Patients With Acute-on-Chronic Liver Failure-A Retrospective Analysis.

Science.gov (United States)

Gerth, Hans U; Pohlen, Michele; Thölking, Gerold; Pavenstädt, Hermann; Brand, Marcus; Hüsing-Kabar, Anna; Wilms, Christian; Maschmeier, Miriam; Kabar, Iyad; Torner, Josep; Pavesi, Marco; Arroyo, Vicente; Banares, Rafael; Schmidt, Hartmut H J

2017-10-01

Acute-on-chronic liver failure is associated with numerous consecutive organ failures and a high short-term mortality rate. Molecular adsorbent recirculating system therapy has demonstrated beneficial effects on the distinct symptoms, but the associated mortality data remain controversial. Retrospective analysis of acute-on-chronic liver failure patients receiving either standard medical treatment or standard medical treatment and molecular adsorbent recirculating system. Secondary analysis of data from the prospective randomized Recompensation of Exacerbated Liver Insufficiency with Hyperbilirubinemia and/or Encephalopathy and/or Renal Failure trial by applying the recently introduced Chronic Liver Failure-criteria. Medical Departments of University Hospital Muenster (Germany). This analysis was conducted in two parts. First, 101 patients with acute-on-chronic liver failure grades 1-3 and Chronic Liver Failure-C-Organ Failure liver subscore equals to 3 but stable pulmonary function were identified and received either standard medical treatment (standard medical treatment, n = 54) or standard medical treatment and molecular adsorbent recirculating system (n = 47) at the University Hospital Muenster. Second, the results of this retrospective analysis were tested against the Recompensation of Exacerbated Liver Insufficiency with Hyperbilirubinemia and/or Encephalopathy and/or Renal Failure trial. Standard medical treatment and molecular adsorbent recirculating system. Additionally to improved laboratory variables (bilirubin and creatinine), the short-term mortality (up to day 14) of the molecular adsorbent recirculating system group was significantly reduced compared with standard medical treatment. A reduced 14-day mortality rate was observed in the molecular adsorbent recirculating system group (9.5% vs 50.0% with standard medical treatment; p = 0.004), especially in patients with multiple organ failure (acute-on-chronic liver failure grade 2-3). Concerning the

An Application of the Functional Resonance Analysis Method (FRAM) to Risk Assessment of Organisational Change

Energy Technology Data Exchange (ETDEWEB)

Hollnagel, Erik [MINES ParisTech Crisis and Risk Research Centre (CRC), Sophia Antipolis Cedex (France)

2012-11-15

The objective of this study was to demonstrate an alternative approach to risk assessment of organisational changes, based on the principles of resilience engineering. The approach in question was the Functional Resonance Analysis Method (FRAM). Whereas established approaches focus on risks coming from failure or malfunctioning of components, alone or in combination, resilience engineering focuses on the common functions and processes that provide the basis for both successes and failures. Resilience engineering more precisely proposes that failures represent the flip side of the adaptations necessary to cope with the real world complexity rather than a failure of normal system functions and that a safety assessment therefore should focus on how functions are carried out rather than on how they may fail. The objective of this study was not to evaluate the current approach to risk assessment used by the organisation in question. The current approach has nevertheless been used as a frame of reference, but in a non-evaluative manner. The author has demonstrated through the selected case that FRAM can be used as an alternative approach to organizational changes. The report provides the reader with details to consider when making a decision on what analysis approach to use. The choice of which approach to use must reflect priorities and concerns of the organisation and the author makes no statement about which approach is better. It is clear that the choice of an analysis approach is not so simple to make and there are many things to take into account such as the larger working environment, organisational culture, regulatory requirements, etc.

An Application of the Functional Resonance Analysis Method (FRAM) to Risk Assessment of Organisational Change

International Nuclear Information System (INIS)

Hollnagel, Erik

2012-11-01

The objective of this study was to demonstrate an alternative approach to risk assessment of organisational changes, based on the principles of resilience engineering. The approach in question was the Functional Resonance Analysis Method (FRAM). Whereas established approaches focus on risks coming from failure or malfunctioning of components, alone or in combination, resilience engineering focuses on the common functions and processes that provide the basis for both successes and failures. Resilience engineering more precisely proposes that failures represent the flip side of the adaptations necessary to cope with the real world complexity rather than a failure of normal system functions and that a safety assessment therefore should focus on how functions are carried out rather than on how they may fail. The objective of this study was not to evaluate the current approach to risk assessment used by the organisation in question. The current approach has nevertheless been used as a frame of reference, but in a non-evaluative manner. The author has demonstrated through the selected case that FRAM can be used as an alternative approach to organizational changes. The report provides the reader with details to consider when making a decision on what analysis approach to use. The choice of which approach to use must reflect priorities and concerns of the organisation and the author makes no statement about which approach is better. It is clear that the choice of an analysis approach is not so simple to make and there are many things to take into account such as the larger working environment, organisational culture, regulatory requirements, etc

Failure mode and effects analysis and fault tree analysis of surface image guided cranial radiosurgery.

Science.gov (United States)

Manger, Ryan P; Paxton, Adam B; Pawlicki, Todd; Kim, Gwe-Ya

2015-05-01

Surface image guided, Linac-based radiosurgery (SIG-RS) is a modern approach for delivering radiosurgery that utilizes optical stereoscopic imaging to monitor the surface of the patient during treatment in lieu of using a head frame for patient immobilization. Considering the novelty of the SIG-RS approach and the severity of errors associated with delivery of large doses per fraction, a risk assessment should be conducted to identify potential hazards, determine their causes, and formulate mitigation strategies. The purpose of this work is to investigate SIG-RS using the combined application of failure modes and effects analysis (FMEA) and fault tree analysis (FTA), report on the effort required to complete the analysis, and evaluate the use of FTA in conjunction with FMEA. A multidisciplinary team was assembled to conduct the FMEA on the SIG-RS process. A process map detailing the steps of the SIG-RS was created to guide the FMEA. Failure modes were determined for each step in the SIG-RS process, and risk priority numbers (RPNs) were estimated for each failure mode to facilitate risk stratification. The failure modes were ranked by RPN, and FTA was used to determine the root factors contributing to the riskiest failure modes. Using the FTA, mitigation strategies were formulated to address the root factors and reduce the risk of the process. The RPNs were re-estimated based on the mitigation strategies to determine the margin of risk reduction. The FMEA and FTAs for the top two failure modes required an effort of 36 person-hours (30 person-hours for the FMEA and 6 person-hours for two FTAs). The SIG-RS process consisted of 13 major subprocesses and 91 steps, which amounted to 167 failure modes. Of the 91 steps, 16 were directly related to surface imaging. Twenty-five failure modes resulted in a RPN of 100 or greater. Only one of these top 25 failure modes was specific to surface imaging. The riskiest surface imaging failure mode had an overall RPN-rank of eighth

The failure combination method: presentation, application to a simple collection of systems

International Nuclear Information System (INIS)

Llory, M.; Villemeur, A.

1981-11-01

The main advantages of this particular method for analyzing the reliability and safety of systems, the method of failure combinations, are presented. This is an inductive method of analysis; it makes it possible to pursue the Failure Modes and Effect Analysis (FMEA) until overall failures are obtained. In this manner, through an inductive approach all the combinations of failure modes leading to abnormal functioning of systems are obtained. It also makes it possible to carry out the overall study of complex systems in interaction and the systematic inventory of abnormal functioning of these systems, as from the failure modes of the components and their combinations. It can be used as from the design stages of systems and is an excellent dialogue tool between the various specialists concerned in problems of safety, operation and reliability [fr

Importance of competing risks in the analysis of anti-epileptic drug failure

Directory of Open Access Journals (Sweden)

Sander Josemir W

2007-03-01

Full Text Available Abstract Background Retention time (time to treatment failure is a commonly used outcome in antiepileptic drug (AED studies. Methods Two datasets are used to demonstrate the issues in a competing risks analysis of AEDs. First, data collection and follow-up considerations are discussed with reference to information from 15 monotherapy trials. Recommendations for improved data collection and cumulative incidence analysis are then illustrated using the SANAD trial dataset. The results are compared to the more common approach using standard survival analysis methods. Results A non-significant difference in overall treatment failure time between gabapentin and topiramate (logrank test statistic = 0.01, 1 degree of freedom, p-value = 0.91 masked highly significant differences in opposite directions with gabapentin resulting in fewer withdrawals due to side effects (Gray's test statistic = 11.60, 1 degree of freedom, p = 0.0007 but more due to poor seizure control (Gray's test statistic = 14.47, 1 degree of freedom, p-value = 0.0001. The significant difference in overall treatment failure time between lamotrigine and carbamazepine (logrank test statistic = 5.6, 1 degree of freedom, p-value = 0.018 was due entirely to a significant benefit of lamotrigine in terms of side effects (Gray's test statistic = 10.27, 1 degree of freedom, p = 0.001. Conclusion Treatment failure time can be measured reliably but care is needed to collect sufficient information on reasons for drug withdrawal to allow a competing risks analysis. Important differences between the profiles of AEDs may be missed unless appropriate statistical methods are used to fully investigate treatment failure time. Cumulative incidence analysis allows comparison of the probability of failure between two AEDs and is likely to be a more powerful approach than logrank analysis for most comparisons of standard and new anti-epileptic drugs.

Clinical risk analysis with failure mode and effect analysis (FMEA) model in a dialysis unit.

Science.gov (United States)

Bonfant, Giovanna; Belfanti, Pietro; Paternoster, Giuseppe; Gabrielli, Danila; Gaiter, Alberto M; Manes, Massimo; Molino, Andrea; Pellu, Valentina; Ponzetti, Clemente; Farina, Massimo; Nebiolo, Pier E

2010-01-01

The aim of clinical risk management is to improve the quality of care provided by health care organizations and to assure patients' safety. Failure mode and effect analysis (FMEA) is a tool employed for clinical risk reduction. We applied FMEA to chronic hemodialysis outpatients. FMEA steps: (i) process study: we recorded phases and activities. (ii) Hazard analysis: we listed activity-related failure modes and their effects; described control measures; assigned severity, occurrence and detection scores for each failure mode and calculated the risk priority numbers (RPNs) by multiplying the 3 scores. Total RPN is calculated by adding single failure mode RPN. (iii) Planning: we performed a RPNs prioritization on a priority matrix taking into account the 3 scores, and we analyzed failure modes causes, made recommendations and planned new control measures. (iv) Monitoring: after failure mode elimination or reduction, we compared the resulting RPN with the previous one. Our failure modes with the highest RPN came from communication and organization problems. Two tools have been created to ameliorate information flow: "dialysis agenda" software and nursing datasheets. We scheduled nephrological examinations, and we changed both medical and nursing organization. Total RPN value decreased from 892 to 815 (8.6%) after reorganization. Employing FMEA, we worked on a few critical activities, and we reduced patients' clinical risk. A priority matrix also takes into account the weight of the control measures: we believe this evaluation is quick, because of simple priority selection, and that it decreases action times.

Failure rate and reliability of the KOMATSU hydraulic excavator in surface limestone mine

Science.gov (United States)

Harish Kumar N., S.; Choudhary, R. P.; Murthy, Ch. S. N.

2018-04-01

The model with failure rate function of bathtub-shaped is helpful in reliability analysis of any system and particularly in reliability associated privative maintenance. The usual Weibull distribution is, however, not capable to model the complete lifecycle of the any with a bathtub-shaped failure rate function. In this paper, failure rate and reliability analysis of the KOMATSU hydraulic excavator/shovel in surface mine is presented and also to improve the reliability and decrease the failure rate of each subsystem of the shovel based on the preventive maintenance. The model of the bathtub-shaped for shovel can also be seen as a simplification of the Weibull distribution.

Application of failure mode and effect analysis in a radiology department.

Science.gov (United States)

Thornton, Eavan; Brook, Olga R; Mendiratta-Lala, Mishal; Hallett, Donna T; Kruskal, Jonathan B

2011-01-01

With increasing deployment, complexity, and sophistication of equipment and related processes within the clinical imaging environment, system failures are more likely to occur. These failures may have varying effects on the patient, ranging from no harm to devastating harm. Failure mode and effect analysis (FMEA) is a tool that permits the proactive identification of possible failures in complex processes and provides a basis for continuous improvement. This overview of the basic principles and methodology of FMEA provides an explanation of how FMEA can be applied to clinical operations in a radiology department to reduce, predict, or prevent errors. The six sequential steps in the FMEA process are explained, and clinical magnetic resonance imaging services are used as an example for which FMEA is particularly applicable. A modified version of traditional FMEA called Healthcare Failure Mode and Effect Analysis, which was introduced by the U.S. Department of Veterans Affairs National Center for Patient Safety, is briefly reviewed. In conclusion, FMEA is an effective and reliable method to proactively examine complex processes in the radiology department. FMEA can be used to highlight the high-risk subprocesses and allows these to be targeted to minimize the future occurrence of failures, thus improving patient safety and streamlining the efficiency of the radiology department. RSNA, 2010

Exact combinatorial reliability analysis of dynamic systems with sequence-dependent failures

International Nuclear Information System (INIS)

Xing Liudong; Shrestha, Akhilesh; Dai Yuanshun

2011-01-01

Many real-life fault-tolerant systems are subjected to sequence-dependent failure behavior, in which the order in which the fault events occur is important to the system reliability. Such systems can be modeled by dynamic fault trees (DFT) with priority-AND (pAND) gates. Existing approaches for the reliability analysis of systems subjected to sequence-dependent failures are typically state-space-based, simulation-based or inclusion-exclusion-based methods. Those methods either suffer from the state-space explosion problem or require long computation time especially when results with high degree of accuracy are desired. In this paper, an analytical method based on sequential binary decision diagrams is proposed. The proposed approach can analyze the exact reliability of non-repairable dynamic systems subjected to the sequence-dependent failure behavior. Also, the proposed approach is combinatorial and is applicable for analyzing systems with any arbitrary component time-to-failure distributions. The application and advantages of the proposed approach are illustrated through analysis of several examples. - Highlights: → We analyze the sequence-dependent failure behavior using combinatorial models. → The method has no limitation on the type of time-to-failure distributions. → The method is analytical and based on sequential binary decision diagrams (SBDD). → The method is computationally more efficient than existing methods.

Probabilistic Design Analysis (PDA) Approach to Determine the Probability of Cross-System Failures for a Space Launch Vehicle

Science.gov (United States)

Shih, Ann T.; Lo, Yunnhon; Ward, Natalie C.

2010-01-01

Quantifying the probability of significant launch vehicle failure scenarios for a given design, while still in the design process, is critical to mission success and to the safety of the astronauts. Probabilistic risk assessment (PRA) is chosen from many system safety and reliability tools to verify the loss of mission (LOM) and loss of crew (LOC) requirements set by the NASA Program Office. To support the integrated vehicle PRA, probabilistic design analysis (PDA) models are developed by using vehicle design and operation data to better quantify failure probabilities and to better understand the characteristics of a failure and its outcome. This PDA approach uses a physics-based model to describe the system behavior and response for a given failure scenario. Each driving parameter in the model is treated as a random variable with a distribution function. Monte Carlo simulation is used to perform probabilistic calculations to statistically obtain the failure probability. Sensitivity analyses are performed to show how input parameters affect the predicted failure probability, providing insight for potential design improvements to mitigate the risk. The paper discusses the application of the PDA approach in determining the probability of failure for two scenarios from the NASA Ares I project

Dependency Defence and Dependency Analysis Guidance. Volume 1: Summary and Guidance (Appendix 1-2). How to analyse and protect against dependent failures. Summary report of the Nordic Working group on Common Cause Failure Analysis

International Nuclear Information System (INIS)

Johanson, Gunnar; Hellstroem, Per; Makamo, Tuomas; Bento, Jean-Pierre; Knochenhauer, Michael; Poern, Kurt

2003-10-01

The safety systems in Nordic nuclear power plants are characterised by substantial redundancy and/or diversification in safety critical functions, as well as by physical separation of critical safety systems, including their support functions. Viewed together with the evident additional fact, that the single failure criterion has been systematically applied in the design of safety systems, this means that the plant risk profile as calculated in existing PSA:s is usually strongly dominated by failures caused by dependencies resulting in the loss of more than one system sub. The overall objective with the working group is to support safety by studying potential and real CCF events, process statistical data and report conclusions and recommendations that can improve the understanding of these events eventually resulting in increased safety. The result is intended for application in NPP operation, maintenance, inspection and risk assessments. The NAFCS project is part of the activities of the Nordic PSA Group (NPSAG), and is financed jointly by the Nordic utilities and authorities. The work is divided into one quantitative and one qualitative part with the following specific objectives: Qualitative objectives-The goal with the qualitative analysis is to compile experience data and generate insights in terms of relevant failure mechanisms and effective CCF protection measures. The results shall be presented as a guide with checklists and recommendations on how to identify current CCF protection standard and improvement possibilities regarding CCF defences decreasing the CCF vulnerability. Quantitative objectives-The goal with the quantitative analysis is to prepare a Nordic C-book where quantitative insights as Impact Vectors and CCF parameters for different redundancy levels are presented. Uncertainties in CCF data shall be reduced as much as possible. The high redundancy systems sensitivity to CCF events demand a well structured quantitative analysis in support of

LIF: A new Kriging based learning function and its application to structural reliability analysis

International Nuclear Information System (INIS)

Sun, Zhili; Wang, Jian; Li, Rui; Tong, Cao

2017-01-01

The main task of structural reliability analysis is to estimate failure probability of a studied structure taking randomness of input variables into account. To consider structural behavior practically, numerical models become more and more complicated and time-consuming, which increases the difficulty of reliability analysis. Therefore, sequential strategies of design of experiment (DoE) are raised. In this research, a new learning function, named least improvement function (LIF), is proposed to update DoE of Kriging based reliability analysis method. LIF values how much the accuracy of estimated failure probability will be improved if adding a given point into DoE. It takes both statistical information provided by the Kriging model and the joint probability density function of input variables into account, which is the most important difference from the existing learning functions. Maximum point of LIF is approximately determined with Markov Chain Monte Carlo(MCMC) simulation. A new reliability analysis method is developed based on the Kriging model, in which LIF, MCMC and Monte Carlo(MC) simulation are employed. Three examples are analyzed. Results show that LIF and the new method proposed in this research are very efficient when dealing with nonlinear performance function, small probability, complicated limit state and engineering problems with high dimension. - Highlights: • Least improvement function (LIF) is proposed for structural reliability analysis. • LIF takes both Kriging based statistical information and joint PDF into account. • A reliability analysis method is constructed based on Kriging, MCS and LIF.

Efficient surrogate models for reliability analysis of systems with multiple failure modes

International Nuclear Information System (INIS)

Bichon, Barron J.; McFarland, John M.; Mahadevan, Sankaran

2011-01-01

Despite many advances in the field of computational reliability analysis, the efficient estimation of the reliability of a system with multiple failure modes remains a persistent challenge. Various sampling and analytical methods are available, but they typically require accepting a tradeoff between accuracy and computational efficiency. In this work, a surrogate-based approach is presented that simultaneously addresses the issues of accuracy, efficiency, and unimportant failure modes. The method is based on the creation of Gaussian process surrogate models that are required to be locally accurate only in the regions of the component limit states that contribute to system failure. This approach to constructing surrogate models is demonstrated to be both an efficient and accurate method for system-level reliability analysis. - Highlights: → Extends efficient global reliability analysis to systems with multiple failure modes. → Constructs locally accurate Gaussian process models of each response. → Highly efficient and accurate method for assessing system reliability. → Effectiveness is demonstrated on several test problems from the literature.

Timing analysis of PWR fuel pin failures

International Nuclear Information System (INIS)

Jones, K.R.; Wade, N.L.; Katsma, K.R.; Siefken, L.J.; Straka, M.

1992-09-01

Research has been conducted to develop and demonstrate a methodology for calculation of the time interval between receipt of the containment isolation signals and the first fuel pin failure for loss-of-coolant accidents (LOCAs). Demonstration calculations were performed for a Babcock and Wilcox (B ampersand W) design (Oconee) and a Westinghouse (W) four-loop design (Seabrook). Sensitivity studies were performed to assess the impacts of fuel pin bumup, axial peaking factor, break size, emergency core cooling system availability, and main coolant pump trip on these times. The analysis was performed using the following codes: FRAPCON-2, for the calculation of steady-state fuel behavior; SCDAP/RELAP5/MOD3 and TRACPF1/MOD1, for the calculation of the transient thermal-hydraulic conditions in the reactor system; and FRAP-T6, for the calculation of transient fuel behavior. In addition to the calculation of fuel pin failure timing, this analysis provides a comparison of the predicted results of SCDAP/RELAP5/MOD3 and TRAC-PFL/MOD1 for large-break LOCA analysis. Using SCDAP/RELAP5/MOD3 thermal-hydraulic data, the shortest time intervals calculated between initiation of containment isolation and fuel pin failure are 10.4 seconds and 19.1 seconds for the B ampersand W and W plants, respectively. Using data generated by TRAC-PF1/MOD1, the shortest intervals are 10.3 seconds and 29.1 seconds for the B ampersand W and W plants, respectively. These intervals are for a double-ended, offset-shear, cold leg break, using the technical specification maximum peaking factor and applied to fuel with maximum design bumup. Using peaking factors commensurate widi actual bumups would result in longer intervals for both reactor designs. This document also contains appendices A through J of this report

Failure Mode and Effect Analysis for Wind Turbine Systems in China

DEFF Research Database (Denmark)

Zhu, Jiangsheng; Ma, Kuichao; N. Soltani, Mohsen

2017-01-01

This paper discusses a cost based Failure Mode and Effect Analysis (FMEA) approch for the Wind Turbine (WT) with condition monitoring system in China. Normally, the traditional FMEA uses the Risk Priority Number (RPN) to rank failure modes. But the RPN can be changed with the Condition Monitoring...... Systems (CMS) due to change of the score of detection. The cost of failure mode should also be considered because faults can be detected at an incipient level, and condition-based maintenance can be scheduled. The results show that the proposed failure mode priorities considering their cost consequences...

Reliability analysis and component functional allocations for the ESF multi-loop controller design

International Nuclear Information System (INIS)

Hur, Seop; Kim, D.H.; Choi, J.K.; Park, J.C.; Seong, S.H.; Lee, D.Y.

2006-01-01

This paper deals with the reliability analysis and component functional allocations to ensure the enhanced system reliability and availability. In the Engineered Safety Features, functionally dependent components are controlled by a multi-loop controller. The system reliability of the Engineered Safety Features-Component Control System, especially, the multi-loop controller which is changed comparing to the conventional controllers is an important factor for the Probability Safety Assessment in the nuclear field. To evaluate the multi-loop controller's failure rate of the k-out-of-m redundant system, the binomial process is used. In addition, the component functional allocation is performed to tolerate a single multi-loop controller failure without the loss of vital operation within the constraints of the piping and component configuration, and ensure that mechanically redundant components remain functional. (author)

Guideline-recommended therapy, including beta-blocker utilization, in patients with chronic heart failure: results from a Canadian community hospital heart function clinic

Directory of Open Access Journals (Sweden)

Heffernan M

2016-06-01

Full Text Available Michael Heffernan Division of Cardiology, Oakville Trafalgar Memorial Hospital, Oakville, ON, Canada Abstract: A comprehensive analysis of beta-blocker utilization and other guideline-recommended therapies for the treatment of chronic heart failure in a Canadian community hospital heart function clinic has not been undertaken and was, therefore, the focus of this study. The proportion of patients who would be potential candidates for ivabridine and sacubitril–valsartan therapy as a result of fulfilling the criteria for enrollment in either the Systolic Heart failure treatment with the If inhibitor ivabradine Trial (SHIFT study (left-ventricular ejection fraction [LVEF] >35%, sinus rhythm, New York Heart Association II–IV or the Prospective Comparison of angiotensin receptor-neprilysin inhibitor (ARNI with angiotensin-converting enzyme inhibitor (ACEI to determine impact on global Mortality and Morbidity in Heart Failure (PARADIGM-HF study (LVEF <40%, New York Heart Association II–IV, glomerular filtration rate >30 mL/min, was also assessed. A retrospective cross-sectional analysis was carried out in all 371 patients treated in this community heart function clinic for at least a 12-month period. The patients were elderly (mean age 74±13.3 years and predominately male (61.5% with symptomatic (82.5% moderate left-ventricular dysfunction (LVEF 45.4%±15.6%. A substantial proportion of the patients also had a diagnosis of atrial fibrillation (52.8%. The total use of beta blockers exceeded 87%, while 100% of patients without a documented contraindication or intolerance to a beta blocker received therapy. Adherence to other guideline-recommended pharmacotherapies specifically for heart failure with reduced left ventricular ejection was high: 86.1% of the eligible patients were treated with an ACEI/angiotensin receptor blocker and 61.9% received a mineralcorticoid receptor antagonist. We determined that 13.7% of the complement of this heart

Comprehensive Analysis of Gene Expression Profiles of Sepsis-Induced Multiorgan Failure Identified Its Valuable Biomarkers.

Science.gov (United States)

Wang, Yumei; Yin, Xiaoling; Yang, Fang

2018-02-01

Sepsis is an inflammatory-related disease, and severe sepsis would induce multiorgan dysfunction, which is the most common cause of death of patients in noncoronary intensive care units. Progression of novel therapeutic strategies has proven to be of little impact on the mortality of severe sepsis, and unfortunately, its mechanisms still remain poorly understood. In this study, we analyzed gene expression profiles of severe sepsis with failure of lung, kidney, and liver for the identification of potential biomarkers. We first downloaded the gene expression profiles from the Gene Expression Omnibus and performed preprocessing of raw microarray data sets and identification of differential expression genes (DEGs) through the R programming software; then, significantly enriched functions of DEGs in lung, kidney, and liver failure sepsis samples were obtained from the Database for Annotation, Visualization, and Integrated Discovery; finally, protein-protein interaction network was constructed for DEGs based on the STRING database, and network modules were also obtained through the MCODE cluster method. As a result, lung failure sepsis has the highest number of DEGs of 859, whereas the number of DEGs in kidney and liver failure sepsis samples is 178 and 175, respectively. In addition, 17 overlaps were obtained among the three lists of DEGs. Biological processes related to immune and inflammatory response were found to be significantly enriched in DEGs. Network and module analysis identified four gene clusters in which all or most of genes were upregulated. The expression changes of Icam1 and Socs3 were further validated through quantitative PCR analysis. This study should shed light on the development of sepsis and provide potential therapeutic targets for sepsis-induced multiorgan failure.

Optimal tread design for agricultural lug tires determined through failure analysis

Directory of Open Access Journals (Sweden)

Hyun Seok Song

2018-04-01

Full Text Available Agricultural lug tires, commonly used in tractors, must provide safe and stable support for the body of the vehicle and bear any additional load while effectively traversing rough, poor-quality ground surfaces. Many agricultural lug tires fail unexpectedly. In this study, we optimised and validated a tread design for agricultural lug tires intended to increase their durability using failure analysis. Specifically, we identified tire failure modes using indoor driving tests and failure mode effects analysis. Next, we developed a threedimensional tire model using the Ogden material model and finite element method. Using sensitivity analysis and response surface methodology, we optimised the tread design. Finally, we evaluated the durability of the new design using a tire prototype and drum test equipment. Results indicated that the optimised tread design decreased the tire tread stress by 16% and increased its time until cracking by 38% compared to conventional agricultural lug tires.

Software failure events derivation and analysis by frame-based technique

International Nuclear Information System (INIS)

Huang, H.-W.; Shih, C.; Yih, Swu; Chen, M.-H.

2007-01-01

A frame-based technique, including physical frame, logical frame, and cognitive frame, was adopted to perform digital I and C failure events derivation and analysis for generic ABWR. The physical frame was structured with a modified PCTran-ABWR plant simulation code, which was extended and enhanced on the feedwater system, recirculation system, and steam line system. The logical model is structured with MATLAB, which was incorporated into PCTran-ABWR to improve the pressure control system, feedwater control system, recirculation control system, and automated power regulation control system. As a result, the software failure of these digital control systems can be properly simulated and analyzed. The cognitive frame was simulated by the operator awareness status in the scenarios. Moreover, via an internal characteristics tuning technique, the modified PCTran-ABWR can precisely reflect the characteristics of the power-core flow. Hence, in addition to the transient plots, the analysis results can then be demonstrated on the power-core flow map. A number of postulated I and C system software failure events were derived to achieve the dynamic analyses. The basis for event derivation includes the published classification for software anomalies, the digital I and C design data for ABWR, chapter 15 accident analysis of generic SAR, and the reported NPP I and C software failure events. The case study of this research includes: (1) the software CMF analysis for the major digital control systems; and (2) postulated ABWR digital I and C software failure events derivation from the actual happening of non-ABWR digital I and C software failure events, which were reported to LER of USNRC or IRS of IAEA. These events were analyzed by PCTran-ABWR. Conflicts among plant status, computer status, and human cognitive status are successfully identified. The operator might not easily recognize the abnormal condition, because the computer status seems to progress normally. However, a well

The effect of chronic heart failure and type 2 diabetes on insulin-stimulated endothelial function is similar and additive

DEFF Research Database (Denmark)

Falskov, Britt; Hermann, Thomas Steffen; Rask-Madsen, Christian

2011-01-01

AIM: Chronic heart failure is associated with endothelial dysfunction and insulin resistance. The aim of this investigation was to study insulin-stimulated endothelial function and glucose uptake in skeletal muscles in patients with heart failure in comparison to patients with type 2 diabetes. ME...... in similar vascular insulin resistance and reduced muscular insulin-stimulated glucose uptake. The effects of systolic heart failure and type 2 diabetes appear to be additive.......AIM: Chronic heart failure is associated with endothelial dysfunction and insulin resistance. The aim of this investigation was to study insulin-stimulated endothelial function and glucose uptake in skeletal muscles in patients with heart failure in comparison to patients with type 2 diabetes...

Correlations between respiratory and functional variables in heart failure

Directory of Open Access Journals (Sweden)

Fábio Cangeri Di Naso

2009-09-01

Full Text Available Background: Respiratory alterations can impact on the functional performance of patients with heart failure. Aim: To correlate maximum inspiratory muscular force and lung function variables with functional capacity in heart failure patients. Methods: A transversal study January-July 2007 with 42 chronic heart disease patients (28 males with no prior pulmonary illness. The patients were in New York Heart Association Functional Class I, II and III. The variables used were maximum inspiratory pressure, forced vital capacity and forced expiratory volume in the first second. Respiratory variables measured were distance covered in the six-minute walk test, NYHA functional class and the physical functioning domain of the Short Form-36 Quality of Life Questionnaire. Results: Maximum inspiratory pressure correlated with the six-minute walk test (r = 0.543 and p < 0.001, functional capacity (r = −0.566 and p < 0.001 and the physical functioning domain score of the Short Form-36 (r = 0.459 and p = 0.002. The same was true of forced vital capacity and the six-minute walk test (r = 0.501 and p = 0.001, functional capacity (r = −0.477 and p = 0.001 and Short Form-36 (r = 0.314 and p = 0.043 variables. Forced expiratory volume correlated with the distance covered in the six-minute walk test (r = 0.514 and p < 0.001 and functional capacity (r = −0.383 and p = 0.012. Conclusion: Lung function and inspiratory muscular force respiratory variables correlated with functional variables in patients with heart failure. Resumo: Fundamento: Alterações respiratórias podem influenciar o desempenho funcional em doentes com insuficiência cardíaca (IC. Objectivo: Correlacionar a força muscular inspiratória máxima (PImax e as variáveis da função pulmonar com a capacidade funcional em doentes com IC. Métodos: Estudo transversal

Clinical research on correlation between BNP and left cardiac function in patients with heart failure

International Nuclear Information System (INIS)

Yin Xin; Xu Dandan; Wu Chunxu

2005-01-01

To investigate the correlation between brain natriuretic peptide (BNP) and the cardiac function in patients with heart failure(HF), the plasma level of BNP was determined by IRMA and the left cardiac function parameters were measured on echocardiogram in patients with different grade of HF. The results showed that the plasma level of BNP elevated with the worsening of heart failure (NYHA classification). The plasma levels of BNP were negatively correlated with left ventricular ejection fraction (LVEF) and left ventricular end-diastolic diameter (LVDd). The plasma level of BNP increases significantly along with the severity of HF classified by NYHA, and might be a biochemical parameter for evaluating the left ventricular function. (authors)

The Statistical Analysis of Failure Time Data

CERN Document Server

Kalbfleisch, John D

2011-01-01

Contains additional discussion and examples on left truncation as well as material on more general censoring and truncation patterns.Introduces the martingale and counting process formulation swil lbe in a new chapter.Develops multivariate failure time data in a separate chapter and extends the material on Markov and semi Markov formulations.Presents new examples and applications of data analysis.

Failure analysis a practical guide for manufacturers of electronic components and systems

CERN Document Server

Bâzu, Marius

2011-01-01

Failure analysis is the preferred method to investigate product or process reliability and to ensure optimum performance of electrical components and systems. The physics-of-failure approach is the only internationally accepted solution for continuously improving the reliability of materials, devices and processes. The models have been developed from the physical and chemical phenomena that are responsible for degradation or failure of electronic components and materials and now replace popular distribution models for failure mechanisms such as Weibull or lognormal. Reliability engineers nee

Analysis of the failure of a vacuum spin-pit drive turbine spindle shaft

OpenAIRE

Pettitt, Jason M.

2005-01-01

The Naval Postgraduate School's Rotor Spin Research Facility experienced a failure in the Spring of 2005 in which the rotor dropped from the drive turbine and caused extensive damage. A failure analysis of the drive turbine spindle shaft was conducted in order to determine the cause of failure: whether due to a material or design flaw. Also, a dynamic analysis was conducted in order to determine the natural modes present in the system and the associated frequencies that could have contributed...

Loop diuretics, renal function and clinical outcome in patients with heart failure and reduced ejection fraction

NARCIS (Netherlands)

Damman, Kevin; Kjekshus, John; Wikstrand, John; Cleland, John G. F.; Komajda, Michel; Wedel, Hans; Waagstein, Finn; McMurray, John J. V.

AimWe aimed to study the relationships of loop diuretic dose with renal function and clinical outcomes in patients with chronic heart failure (HF). Methods and resultsLoop diuretic dose at baseline was recorded in patients included in the Controlled Rosuvastatin Multinational Trial in Heart Failure

Worsening renal function definition is insufficient for evaluating acute renal failure in acute heart failure

Science.gov (United States)

Hata, Noritake; Kobayashi, Nobuaki; Okazaki, Hirotake; Matsushita, Masato; Shibata, Yusaku; Nishigoori, Suguru; Uchiyama, Saori; Asai, Kuniya; Shimizu, Wataru

2018-01-01

Abstract Aims Whether or not the definition of a worsening renal function (WRF) is adequate for the evaluation of acute renal failure in patients with acute heart failure is unclear. Methods and results One thousand and eighty‐three patients with acute heart failure were analysed. A WRF, indicated by a change in serum creatinine ≥0.3 mg/mL during the first 5 days, occurred in 360 patients while no‐WRF, indicated by a change <0.3 mg/dL, in 723 patients. Acute kidney injury (AKI) upon admission was defined based on the ratio of the serum creatinine value recorded on admission to the baseline creatinine value and placed into groups based on the degree of AKI: no‐AKI (n = 751), Class R (risk; n = 193), Class I (injury; n = 41), or Class F (failure; n = 98). The patients were assigned to another set of four groups: no‐WRF/no‐AKI (n = 512), no‐WRF/AKI (n = 211), WRF/no‐AKI (n = 239), and WRF/AKI (n = 121). A multivariate logistic regression model found that no‐WRF/AKI and WRF/AKI were independently associated with 365 day mortality (hazard ratio: 1.916; 95% confidence interval: 1.234–2.974 and hazard ratio: 3.622; 95% confidence interval: 2.332–5.624). Kaplan–Meier survival curves showed that the rate of any‐cause death during 1 year was significantly poorer in the no‐WRF/AKI and WRF/AKI groups than in the WRF/no‐AKI and no‐WRF/no‐AKI groups and in Class I and Class F than in Class R and the no‐AKI group. Conclusions The presence of AKI on admission, especially Class I and Class F status, is associated with a poor prognosis despite the lack of a WRF within the first 5 days. The prognostic ability of AKI on admission may be superior to WRF within the first 5 days. PMID:29388735

Failure analysis of motor bearing of sea water pump in nuclear power plant

International Nuclear Information System (INIS)

Bian Chunhua; Zhang Wei

2015-01-01

The motor bearing of sea water pump in Qinshan Phase II Nuclear Power plant broke after only one year's using. This paper introduces failure analysis process of the motor bearing. Chemical composition analysis, metallic phase analysis, micrographic examination, and hardness analysis, dimension analysis of each part of the bearing, as well as the high temperature and low temperature performance analysis of lubricating grease are performed. According to the analysis above mentioned, the failure mode of the bearing is wearing, and the reason of wearing is inappropriate installation of the bearing. (authors)

A Costing Analysis for Decision Making Grid Model in Failure-Based Maintenance

Directory of Open Access Journals (Sweden)

Burhanuddin M. A.

2011-01-01

Full Text Available Background. In current economic downturn, industries have to set good control on production cost, to maintain their profit margin. Maintenance department as an imperative unit in industries should attain all maintenance data, process information instantaneously, and subsequently transform it into a useful decision. Then act on the alternative to reduce production cost. Decision Making Grid model is used to identify strategies for maintenance decision. However, the model has limitation as it consider two factors only, that is, downtime and frequency of failures. We consider third factor, cost, in this study for failure-based maintenance. The objective of this paper is to introduce the formulae to estimate maintenance cost. Methods. Fish bone analysis conducted with Ishikawa model and Decision Making Grid methods are used in this study to reveal some underlying risk factors that delay failure-based maintenance. The goal of the study is to estimate the risk factor that is, repair cost to fit in the Decision Making Grid model. Decision Making grid model consider two variables, frequency of failure and downtime in the analysis. This paper introduces third variable, repair cost for Decision Making Grid model. This approaches give better result to categorize the machines, reduce cost, and boost the earning for the manufacturing plant. Results. We collected data from one of the food processing factories in Malaysia. From our empirical result, Machine C, Machine D, Machine F, and Machine I must be in the Decision Making Grid model even though their frequency of failures and downtime are less than Machine B and Machine N, based on the costing analysis. The case study and experimental results show that the cost analysis in Decision Making Grid model gives more promising strategies in failure-based maintenance. Conclusions. The improvement of Decision Making Grid model for decision analysis with costing analysis is our contribution in this paper for

Uncertainty analysis of reactor safety systems with statistically correlated failure data

International Nuclear Information System (INIS)

Dezfuli, H.; Modarres, M.

1985-01-01

The probability of occurrence of the top event of a fault tree is estimated from failure probability of components that constitute the fault tree. Component failure probabilities are subject to statistical uncertainties. In addition, there are cases where the failure data are statistically correlated. Most fault tree evaluations have so far been based on uncorrelated component failure data. The subject of this paper is the description of a method of assessing the probability intervals for the top event failure probability of fault trees when component failure data are statistically correlated. To estimate the mean and variance of the top event, a second-order system moment method is presented through Taylor series expansion, which provides an alternative to the normally used Monte-Carlo method. For cases where component failure probabilities are statistically correlated, the Taylor expansion terms are treated properly. A moment matching technique is used to obtain the probability distribution function of the top event through fitting a Johnson Ssub(B) distribution. The computer program (CORRELATE) was developed to perform the calculations necessary for the implementation of the method developed. The CORRELATE code is very efficient and consumes minimal computer time. This is primarily because it does not employ the time-consuming Monte-Carlo method. (author)

Study on the relationship between plasma BNP levels and left cardiac function in patients with heart failure

International Nuclear Information System (INIS)

Yin Xin; Xu Dandan; Wu Chunxu

2005-01-01

Objective: To investigate the relationship between plasma brain natriuretic peptide (BNP) levels and cardiac function in patients with heart failure. Methods: Plasma levels of BNP (with IRMA) and left cardiac function parameters (examined with echocardiogram) were obtained in 80 patients with heart failure at admission and repeatedly examined in 43 of them later after 2w treatment a swell as in 30 controls. Results: The plasma BNP levels increased along with the deterioration of cardiac function, with significant differences among the patients with different cardiac function grades (P<0.01). After 2w treatment, the plasma BNP levels were significantly lower than those before (P<0.01). The plasma levels of BNP were negatively correlated with left ventricular ejection fraction (LVEF) and left ventricle fraction shortening, but positively correlated with left ventricular end-systolic diameter (LVSd) and left ventricular end-diastolic diameter (LVDd). Conclusion: Plasma levels of BNP were closely related to the severity of heart failure and could serve as a biochemical marker for assessing the left cardiac function. (authors)

Latent-failure risk estimates for computer control

Science.gov (United States)

Dunn, William R.; Folsom, Rolfe A.; Green, Owen R.

1991-01-01

It is shown that critical computer controls employing unmonitored safety circuits are unsafe. Analysis supporting this result leads to two additional, important conclusions: (1) annual maintenance checks of safety circuit function do not, as widely believed, eliminate latent failure risk; (2) safety risk remains even if multiple, series-connected protection circuits are employed. Finally, it is shown analytically that latent failure risk is eliminated when continuous monitoring is employed.

On the functional failures concept and probabilistic safety margins: challenges in application for evaluation of effectiveness of shutdown systems - 15318

International Nuclear Information System (INIS)

Serghiuta, D.; Tholammakkil, J.

2015-01-01

The use of level-3 reliability approach and the concept of functional failure probability could provide the basis for defining a safety margin metric which would include a limit for the probability of functional failure, in line with the definition of a reliability-based design. It can also allow a quantification of level of confidence, by explicit modeling and quantification of uncertainties, and provide a better framework for representation of actual design and optimization of design margins within an integrated probabilistic-deterministic model. This paper reviews the attributes and challenges in application of functional failure concept in evaluation of risk-informed safety margins using as illustrative example the case of CANDU reactors shutdown systems effectiveness. A risk-informed formulation is first introduced for estimation of a reasonable limit for the functional failure probability using a Swiss cheese model. It is concluded that more research is needed in this area and a deterministic - probabilistic approach may be a reasonable intermediate step for evaluation of functional failure probability at the system level. The views expressed in this paper are those of the authors and do not necessarily reflect those of CNSC, or any part thereof. (authors)

Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model: A Web-based program designed to evaluate the cost-effectiveness of disease management programs in heart failure.

Science.gov (United States)

Reed, Shelby D; Neilson, Matthew P; Gardner, Matthew; Li, Yanhong; Briggs, Andrew H; Polsky, Daniel E; Graham, Felicia L; Bowers, Margaret T; Paul, Sara C; Granger, Bradi B; Schulman, Kevin A; Whellan, David J; Riegel, Barbara; Levy, Wayne C

2015-11-01

Heart failure disease management programs can influence medical resource use and quality-adjusted survival. Because projecting long-term costs and survival is challenging, a consistent and valid approach to extrapolating short-term outcomes would be valuable. We developed the Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model, a Web-based simulation tool designed to integrate data on demographic, clinical, and laboratory characteristics; use of evidence-based medications; and costs to generate predicted outcomes. Survival projections are based on a modified Seattle Heart Failure Model. Projections of resource use and quality of life are modeled using relationships with time-varying Seattle Heart Failure Model scores. The model can be used to evaluate parallel-group and single-cohort study designs and hypothetical programs. Simulations consist of 10,000 pairs of virtual cohorts used to generate estimates of resource use, costs, survival, and incremental cost-effectiveness ratios from user inputs. The model demonstrated acceptable internal and external validity in replicating resource use, costs, and survival estimates from 3 clinical trials. Simulations to evaluate the cost-effectiveness of heart failure disease management programs across 3 scenarios demonstrate how the model can be used to design a program in which short-term improvements in functioning and use of evidence-based treatments are sufficient to demonstrate good long-term value to the health care system. The Tools for Economic Analysis of Patient Management Interventions in Heart Failure Cost-Effectiveness Model provides researchers and providers with a tool for conducting long-term cost-effectiveness analyses of disease management programs in heart failure. Copyright © 2015 Elsevier Inc. All rights reserved.

Patterns of Failure After MammoSite Brachytherapy Partial Breast Irradiation: A Detailed Analysis

International Nuclear Information System (INIS)

Chen, Sea; Dickler, Adam; Kirk, Michael; Shah, Anand; Jokich, Peter; Solmos, Gene; Strauss, Jonathan; Dowlatshahi, Kambiz; Nguyen, Cam; Griem, Katherine

2007-01-01

Purpose: To report the results of a detailed analysis of treatment failures after MammoSite breast brachytherapy for partial breast irradiation from our single-institution experience. Methods and Materials: Between October 14, 2002 and October 23, 2006, 78 patients with early-stage breast cancer were treated with breast-conserving surgery and accelerated partial breast irradiation using the MammoSite brachytherapy applicator. We identified five treatment failures in the 70 patients with >6 months' follow-up. Pathologic data, breast imaging, and radiation treatment plans were reviewed. For in-breast failures more than 2 cm away from the original surgical bed, the doses delivered to the areas of recurrence by partial breast irradiation were calculated. Results: At a median follow-up time of 26.1 months, five treatment failures were identified. There were three in-breast failures more than 2 cm away from the original surgical bed, one failure directly adjacent to the original surgical bed, and one failure in the axilla with synchronous distant metastases. The crude failure rate was 7.1% (5 of 70), and the crude local failure rate was 5.7% (4 of 70). Estimated progression-free survival at 48 months was 89.8% (standard error 4.5%). Conclusions: Our case series of 70 patients with >6 months' follow-up and a median follow-up of 26 months is the largest single-institution report to date with detailed failure analysis associated with MammoSite brachytherapy. Our failure data emphasize the importance of patient selection when offering partial breast irradiation

Total time on test processes and applications to failure data analysis

International Nuclear Information System (INIS)

Barlow, R.E.; Campo, R.

1975-01-01

This paper describes a new method for analyzing data. The method applies to non-negative observations such as times to failure of devices and survival times of biological organisms and involves a plot of the data. These plots are useful in choosing a probabilistic model to represent the failure behavior of the data. They also furnish information about the failure rate function and aid in its estimation. An important feature of these data plots is that incomplete data can be analyzed. The underlying random variables are, however, assumed to be independent and identically distributed. The plots have a theoretical basis, and converge to a transform of the underlying probability distribution as the sample size increases

Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge

Science.gov (United States)

Li, N.; Cheng, Y. M.

2014-09-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

The distributed failure probability approach to dependent failure analysis, and its application

International Nuclear Information System (INIS)

Hughes, R.P.

1989-01-01

The Distributed Failure Probability (DFP) approach to the problem of dependent failures in systems is presented. The basis of the approach is that the failure probability of a component is a variable. The source of this variability is the change in the 'environment' of the component, where the term 'environment' is used to mean not only obvious environmental factors such as temperature etc., but also such factors as the quality of maintenance and manufacture. The failure probability is distributed among these various 'environments' giving rise to the Distributed Failure Probability method. Within the framework which this method represents, modelling assumptions can be made, based both on engineering judgment and on the data directly. As such, this DFP approach provides a soundly based and scrutable technique by which dependent failures can be quantitatively assessed. (orig.)

Failure analysis of multiple delaminated composite plates due

Indian Academy of Sciences (India)

The present work aims at the first ply failure analysis of laminated composite plates with arbitrarily located multiple delaminations subjected to transverse static load as well as impact. The theoretical formulation is based on a simple multiple delamination model. Conventional first order shear deformation is assumed using ...

Exploitation of a component event data bank for common cause failure analysis

International Nuclear Information System (INIS)

Games, A.M.; Amendola, A.; Martin, P.

1985-01-01

Investigations into using the European Reliability Data System Component Event Data Bank for common cause failure analysis have been carried out. Starting from early exercises where data were analyzed without computer aid, different types of linked multiple failures have been identified. A classification system is proposed based on this experience. It defines a multiple failure event space wherein each category defines causal, modal, temporal and structural links between failures. It is shown that a search algorithm which incorporates the specific interrogative procedures of the data bank can be developed in conjunction with this classification system. It is concluded that the classification scheme and the search algorithm are useful organizational tools in the field of common cause failures studies. However, it is also suggested that the use of the term common cause failure should be avoided since it embodies to many different types of linked multiple failures

Health related quality of life in patients with congestive heart failure: comparison with other chronic diseases and relation to functional variables.

Science.gov (United States)

Juenger, J; Schellberg, D; Kraemer, S; Haunstetter, A; Zugck, C; Herzog, W; Haass, M

2002-03-01

To assess health related quality of life of patients with congestive heart failure; to compare their quality of life with the previously characterised general population and in those with other chronic diseases; and to correlate the different aspects of quality of life with relevant somatic variables. University hospital. A German version of the generic quality of life measure (SF-36) containing eight dimensions was administered to 205 patients with congestive heart failure and systolic dysfunction. Cardiopulmonary evaluation included assessment of New York Heart Association (NYHA) functional class, left ventricular ejection fraction, peak oxygen uptake, and the distance covered during a standardised six minute walk test. Quality of life significantly decreased with NYHA functional class (linear trend: p < 0.0001). In NYHA class III, the scores of five of the eight quality of life domains were reduced to around one third of those in the general population. The pattern of reduction was different in patients with chronic hepatitis C and major depression, and similar in patients on chronic haemodialysis. Multiple regression analysis showed that only the NYHA functional class was consistently and closely associated with all quality of life scales. The six minute walk test and peak oxygen uptake added to the explanation of the variance in only one of the eight quality of life domains (physical functioning). Left ventricular ejection fraction, duration of disease, and age showed no clear association with quality of life. In congestive heart failure, quality of life decreases as NYHA functional class worsens. Though NYHA functional class was the most dominant predictor among the somatic variables studied, the major determinants of reduced quality of life remain unknown.

Sensor Failure Detection of FASSIP System using Principal Component Analysis

Science.gov (United States)

Sudarno; Juarsa, Mulya; Santosa, Kussigit; Deswandri; Sunaryo, Geni Rina

2018-02-01

In the nuclear reactor accident of Fukushima Daiichi in Japan, the damages of core and pressure vessel were caused by the failure of its active cooling system (diesel generator was inundated by tsunami). Thus researches on passive cooling system for Nuclear Power Plant are performed to improve the safety aspects of nuclear reactors. The FASSIP system (Passive System Simulation Facility) is an installation used to study the characteristics of passive cooling systems at nuclear power plants. The accuracy of sensor measurement of FASSIP system is essential, because as the basis for determining the characteristics of a passive cooling system. In this research, a sensor failure detection method for FASSIP system is developed, so the indication of sensor failures can be detected early. The method used is Principal Component Analysis (PCA) to reduce the dimension of the sensor, with the Squarred Prediction Error (SPE) and statistic Hotteling criteria for detecting sensor failure indication. The results shows that PCA method is capable to detect the occurrence of a failure at any sensor.

Statistical analysis of operating efficiency and failures of a medical linear accelerator for ten years

International Nuclear Information System (INIS)

Ju, Sang Gyu; Huh, Seung Jae; Han, Young Yih

2005-01-01

To improve the management of a medical linear accelerator, the records of operational failures of a Varian CL2100C over a ten year period were retrospectively analyzed. The failures were classified according to the involved functional subunits, with each class rated into one of three levels depending on the operational conditions. The relationships between the failure rate and working ratio and between the failure rate and outside temperature were investigated. In addition, the average life time of the main part and the operating efficiency over the last 4 years were analyzed. Among the recorded failures (total 587 failures), the most frequent failure was observed in the parts related with the collimation system, including the monitor chamber, which accounted for 20% of all failures. With regard to the operational conditions, 2nd level of failures, which temporally interrupted treatments, were the most frequent. Third level of failures, which interrupted treatment for more than several hours, were mostly caused by the accelerating subunit. The number of failures was increased with number of treatments and operating time. The average life-times of the Klystron and Thyratron became shorter as the working ratio increased, and were 42 and 83% of the expected values, respectively. The operating efficiency was maintained at 95% or higher, but this value slightly decreased. There was no significant correlation between the number of failures and the outside temperature. The maintenance of detailed equipment problems and failures records over a long period of time can provide good knowledge of equipment function as well as the capability of predicting future failure. More rigorous equipment maintenance is required for old medical linear accelerators for the advanced avoidance of serious failure and to improve the quality of patient treatment

Finite Element Creep-Fatigue Analysis of a Welded Furnace Roll for Identifying Failure Root Cause

Science.gov (United States)

Yang, Y. P.; Mohr, W. C.

2015-11-01

Creep-fatigue induced failures are often observed in engineering components operating under high temperature and cyclic loading. Understanding the creep-fatigue damage process and identifying failure root cause are very important for preventing such failures and improving the lifetime of engineering components. Finite element analyses including a heat transfer analysis and a creep-fatigue analysis were conducted to model the cyclic thermal and mechanical process of a furnace roll in a continuous hot-dip coating line. Typically, the roll has a short life, modeling heat convection from hot air inside the furnace. The creep-fatigue analysis was performed by inputting the predicted temperature history and applying mechanical loads. The analysis results showed that the failure was resulted from a creep-fatigue mechanism rather than a creep mechanism. The difference of material properties between the filler metal and the base metal is the root cause for the roll failure, which induces higher creep strain and stress in the interface between the weld and the HAZ.

Node vulnerability of water distribution networks under cascading failures

International Nuclear Information System (INIS)

Shuang, Qing; Zhang, Mingyuan; Yuan, Yongbo

2014-01-01

Water distribution networks (WDNs) are important in modern lifeline system. Its stability and reliability are critical for guaranteeing high living quality and continuous operation of urban functions. The aim of this paper is to evaluate the nodal vulnerability of WDNs under cascading failures. Vulnerability is defined to analyze the effects of the consequent failures. A cascading failure is a step-by-step process which is quantitatively investigated by numerical simulation with intentional attack. Monitored pressures in different nodes and flows in different pipes have been used to estimate the network topological structure and the consequences of nodal failure. Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. A load variation function is established to record the nodal failure reason and describe the relative differences between the load and the capacity. The proposed method is validated by an illustrative example. The results revealed that the network vulnerability should be evaluated with the consideration of hydraulic analysis and network topology. In the case study, 70.59% of the node failures trigger the cascading failures with different failure processes. It is shown that the cascading failures result in severe consequences in WDNs. - Highlights: • The aim of this paper is to evaluate the nodal vulnerability of water distribution networks under cascading failures. • Monitored pressures and flows have been used to estimate the network topological structure and the consequences of nodal failure. • Based on the connectivity loss of topological structure, the nodal vulnerability has been evaluated. • A load variation function is established to record the failure reason and describe the relative differences between load and capacity. • The results show that 70.59% of the node failures trigger the cascading failures with different failure processes

Failure detection system risk reduction assessment

Science.gov (United States)

Aguilar, Robert B. (Inventor); Huang, Zhaofeng (Inventor)

2012-01-01

A process includes determining a probability of a failure mode of a system being analyzed reaching a failure limit as a function of time to failure limit, determining a probability of a mitigation of the failure mode as a function of a time to failure limit, and quantifying a risk reduction based on the probability of the failure mode reaching the failure limit and the probability of the mitigation.

MELAS syndrome and cardiomyopathy: linking mitochondrial function to heart failure pathogenesis.

Science.gov (United States)

Hsu, Ying-Han R; Yogasundaram, Haran; Parajuli, Nirmal; Valtuille, Lucas; Sergi, Consolato; Oudit, Gavin Y

2016-01-01

Heart failure remains an important clinical burden, and mitochondrial dysfunction plays a key role in its pathogenesis. The heart has a high metabolic demand, and mitochondrial function is a key determinant of myocardial performance. In mitochondrial disorders, hypertrophic remodeling is the early pattern of cardiomyopathy with progression to dilated cardiomyopathy, conduction defects and ventricular pre-excitation occurring in a significant proportion of patients. Cardiac dysfunction occurs in approximately a third of patients with mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome, a stereotypical example of a mitochondrial disorder leading to a cardiomyopathy. We performed unique comparative ultrastructural and gene expression in a MELAS heart compared with non-failing controls. Our results showed a remarkable increase in mitochondrial inclusions and increased abnormal mitochondria in MELAS cardiomyopathy coupled with variable sarcomere thickening, heterogeneous distribution of affected cardiomyocytes and a greater elevation in the expression of disease markers. Investigation and management of patients with mitochondrial cardiomyopathy should follow the well-described contemporary heart failure clinical practice guidelines and include an important role of medical and device therapies. Directed metabolic therapy is lacking, but current research strategies are dedicated toward improving mitochondrial function in patients with mitochondrial disorders.

Experimental and theoretical analysis of shear wall failure

International Nuclear Information System (INIS)

Gantenbein, F.; Queval, J.C.; Dalbera, J.

1993-01-01

Thirteen walls with and without openings have been tested under seismic loading up to collapse and the test results have already been reported. A global model has been developed for the description of the hysteretic behaviour; it is based on the use of secant stiffness up to the steel yielding and on a slip model after yielding. Applications of this model to the walls with and without openings will be shown and the calculated top displacement will be compared with the measured one. The input load level leading to the failure is calculated with this non-linear model and the results are compared with the experimental values. The safety margin, which is defined as the ratio of the experimental load level leading to the failure to that obtained by linear calculation, will be given as a function of the mean excitation frequency

A pragmatic approach to estimate alpha factors for common cause failure analysis

International Nuclear Information System (INIS)

Hassija, Varun; Senthil Kumar, C.; Velusamy, K.

2014-01-01

Highlights: • Estimation of coefficients in alpha factor model for common cause analysis. • A derivation of plant specific alpha factors is demonstrated. • We examine sensitivity of common cause contribution to total system failure. • We compare beta factor and alpha factor models for various redundant configurations. • The use of alpha factors is preferable, especially for large redundant systems. - Abstract: Most of the modern technological systems are deployed with high redundancy but still they fail mainly on account of common cause failures (CCF). Various models such as Beta Factor, Multiple Greek Letter, Binomial Failure Rate and Alpha Factor exists for estimation of risk from common cause failures. Amongst all, alpha factor model is considered most suitable for high redundant systems as it arrives at common cause failure probabilities from a set of ratios of failures and the total component failure probability Q T . In the present study, alpha factor model is applied for the assessment of CCF of safety systems deployed at two nuclear power plants. A method to overcome the difficulties in estimation of the coefficients viz., alpha factors in the model, importance of deriving plant specific alpha factors and sensitivity of common cause contribution to the total system failure probability with respect to hazard imposed by various CCF events is highlighted. An approach described in NUREG/CR-5500 is extended in this study to provide more explicit guidance for a statistical approach to derive plant specific coefficients for CCF analysis especially for high redundant systems. The procedure is expected to aid regulators for independent safety assessment

Analysis of valve failures from the NUCLARR data base

International Nuclear Information System (INIS)

Moore, L.M.

1997-11-01

The Nuclear Computerized Library for Assessing Reactor Reliability (NUCLARR) contains data on component failures with categorical and qualifying information such as component design, normal operating state, system application and safety grade information which is important to the development of risk-based component surveillance testing requirements. This report presents descriptions and results of analyses of valve component failure data and covariate information available in the document Nuclear Computerized Library for Assessing Reactor Reliability Data Manual, Part 3: Hardware Component Failure Data (NUCLARR Data Manual). Although there are substantial records on valve performance, there are many categories of the corresponding descriptors and qualifying information for which specific values are missing. Consequently, this limits the data available for analysis of covariate effects. This report presents cross tabulations by different covariate categories and limited modeling of covariate effects for data subsets with substantive non-missing covariate information

Probabilistic analysis of ''common mode failures''

International Nuclear Information System (INIS)

Easterling, R.G.

1978-01-01

Common mode failure is a topic of considerable interest in reliability and safety analyses of nuclear reactors. Common mode failures are often discussed in terms of examples: two systems fail simultaneously due to an external event such as an earthquake; two components in redundant channels fail because of a common manufacturing defect; two systems fail because a component common to both fails; the failure of one system increases the stress on other systems and they fail. The common thread running through these is a dependence of some sort--statistical or physical--among multiple failure events. However, the nature of the dependence is not the same in all these examples. An attempt is made to model situations, such as the above examples, which have been termed ''common mode failures.'' In doing so, it is found that standard probability concepts and terms, such as statistically dependent and independent events, and conditional and unconditional probabilities, suffice. Thus, it is proposed that the term ''common mode failures'' be dropped, at least from technical discussions of these problems. A corollary is that the complementary term, ''random failures,'' should also be dropped. The mathematical model presented may not cover all situations which have been termed ''common mode failures,'' but provides insight into the difficulty of obtaining estimates of the probabilities of these events

Statistical Analysis Of Failure Strength Of Material Using Weibull Distribution

International Nuclear Information System (INIS)

Entin Hartini; Mike Susmikanti; Antonius Sitompul

2008-01-01

In evaluation of ceramic and glass materials strength a statistical approach is necessary Strength of ceramic and glass depend on its measure and size distribution of flaws in these material. The distribution of strength for ductile material is narrow and close to a Gaussian distribution while strength of brittle materials as ceramic and glass following Weibull distribution. The Weibull distribution is an indicator of the failure of material strength resulting from a distribution of flaw size. In this paper, cumulative probability of material strength to failure probability, cumulative probability of failure versus fracture stress and cumulative probability of reliability of material were calculated. Statistical criteria calculation supporting strength analysis of Silicon Nitride material were done utilizing MATLAB. (author)

Acetylcysteine reduces plasma homocysteine concentration and improves pulse pressure and endothelial function in patients with end-stage renal failure

DEFF Research Database (Denmark)

Scholze, Alexandra; Rinder, Christiane; Beige, Joachim

2004-01-01

Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure.......Increased oxidative stress, elevated plasma homocysteine concentration, increased pulse pressure, and impaired endothelial function constitute risk factors for increased mortality in patients with end-stage renal failure....

Extracellular matrix remodeling in patients with ischemic chronic heart failure with preserved ejection fraction

Directory of Open Access Journals (Sweden)

V. D. Syvolap

2015-04-01

Full Text Available Aim. To identify features, relationships between parameters of the extracellular matrix and renal function in 110 patients with ischemic chronic heart failure the activity of collagen metabolism markers (MMP-9, TIMP-1, PICP, cystatin C, structural and functional parameters of the heart were studied using ELISA, echocardiography. Results. It was established that imbalance in the system MMP/TIMP in ischemic heart failure with preserved left ventricular ejection fraction leads to disruption of the extracellular matrix structural functional sufficiency, increases functional failure and is associated with impaired renal function. Conclusion. Correlation analysis showed significant relationships between MMP/TIMP and GFR, cystatin C, indicating that the significant role of extracellular matrix imbalance in the development of renal dysfunction in patients with ischemic chronic heart failure.

Failure analysis and modeling of a multicomputer system. M.S. Thesis

Science.gov (United States)

Subramani, Sujatha Srinivasan

1990-01-01

This thesis describes the results of an extensive measurement-based analysis of real error data collected from a 7-machine DEC VaxCluster multicomputer system. In addition to evaluating basic system error and failure characteristics, we develop reward models to analyze the impact of failures and errors on the system. The results show that, although 98 percent of errors in the shared resources recover, they result in 48 percent of all system failures. The analysis of rewards shows that the expected reward rate for the VaxCluster decreases to 0.5 in 100 days for a 3 out of 7 model, which is well over a 100 times that for a 7-out-of-7 model. A comparison of the reward rates for a range of k-out-of-n models indicates that the maximum increase in reward rate (0.25) occurs in going from the 6-out-of-7 model to the 5-out-of-7 model. The analysis also shows that software errors have the lowest reward (0.2 vs. 0.91 for network errors). The large loss in reward rate for software errors is due to the fact that a large proportion (94 percent) of software errors lead to failure. In comparison, the high reward rate for network errors is due to fast recovery from a majority of these errors (median recovery duration is 0 seconds).

Failure characteristics analysis and fault diagnosis for liquid rocket engines

CERN Document Server

Zhang, Wei

2016-01-01

This book concentrates on the subject of health monitoring technology of Liquid Rocket Engine (LRE), including its failure analysis, fault diagnosis and fault prediction. Since no similar issue has been published, the failure pattern and mechanism analysis of the LRE from the system stage are of particular interest to the readers. Furthermore, application cases used to validate the efficacy of the fault diagnosis and prediction methods of the LRE are different from the others. The readers can learn the system stage modeling, analyzing and testing methods of the LRE system as well as corresponding fault diagnosis and prediction methods. This book will benefit researchers and students who are pursuing aerospace technology, fault detection, diagnostics and corresponding applications.

Evaluation of common mode failure of safety functions for limiting fault events

International Nuclear Information System (INIS)

Rezendes, J.P.; Hyde, A.W.

2004-01-01

The draft U.S. Nuclear Regulatory Commission (NRC) policy on digital protection system software requires all Advanced Light Water Reactors (ALWRs) to be evaluated assuming a hypothetical common mode failure (CMF) which incapacitates the normal automatic initiation of safety functions. The System 80 + ALWR has been evaluated for such hypothetical conditions. The results show that the diverse automatic and manual protective systems in System 80 + provide ample safety performance margins relative to core coolability, offsite radiological releases. Reactor Coolant System (RCS) pressurization and containment integrity. This deterministic evaluation served to quantify the significant inherent safety margins in the System 80 + Standard Plant design even in the event of this extremely low probability scenario of a common mode failure. (author)

The Cumulative Effect of Neglect and Failure to Thrive on Cognitive Functioning.

Science.gov (United States)

Mackner, Laura M.; And Others

1997-01-01

A study of 177 low-income children (ages 3-30 months) investigated the relationship among neglect, failure to thrive (FTT), and cognitive functioning. The cognitive performance of children who had been neglected and were FTT was significantly below that of children who had only one of the variables and typical children. (Author/CR)

Failure analysis on false call probe pins of microprocessor test equipment

Science.gov (United States)

Tang, L. W.; Ong, N. R.; Mohamad, I. S. B.; Alcain, J. B.; Retnasamy, V.

2017-09-01

A study has been conducted to investigate failure analysis on probe pins of test modules for microprocessor. The `health condition' of the probe pin is determined by the resistance value. A test module of 5V power supplied from Arduino UNO with "Four-wire Ohm measurement" method is implemented in this study to measure the resistance of the probe pins of a microprocessor. The probe pins from a scrapped computer motherboard is used as the test sample in this study. The functionality of the test module was validated with the pre-measurement experiment via VEE Pro software. Lastly, the experimental work have demonstrated that the implemented test module have the capability to identify the probe pin's `health condition' based on the measured resistance value.

Advanced approaches to failure mode and effect analysis (FMEA applications

Directory of Open Access Journals (Sweden)

D. Vykydal

2015-10-01

Full Text Available The present paper explores advanced approaches to the FMEA method (Failure Mode and Effect Analysis which take into account the costs associated with occurrence of failures during the manufacture of a product. Different approaches are demonstrated using an example FMEA application to production of drawn wire. Their purpose is to determine risk levels, while taking account of the above-mentioned costs. Finally, the resulting priority levels are compared for developing actions mitigating the risks.

Failure analysis of storage tank component in LNG regasification unit using fault tree analysis method (FTA)

Science.gov (United States)

Mulyana, Cukup; Muhammad, Fajar; Saad, Aswad H.; Mariah, Riveli, Nowo

2017-03-01

Storage tank component is the most critical component in LNG regasification terminal. It has the risk of failure and accident which impacts to human health and environment. Risk assessment is conducted to detect and reduce the risk of failure in storage tank. The aim of this research is determining and calculating the probability of failure in regasification unit of LNG. In this case, the failure is caused by Boiling Liquid Expanding Vapor Explosion (BLEVE) and jet fire in LNG storage tank component. The failure probability can be determined by using Fault Tree Analysis (FTA). Besides that, the impact of heat radiation which is generated is calculated. Fault tree for BLEVE and jet fire on storage tank component has been determined and obtained with the value of failure probability for BLEVE of 5.63 × 10-19 and for jet fire of 9.57 × 10-3. The value of failure probability for jet fire is high enough and need to be reduced by customizing PID scheme of regasification LNG unit in pipeline number 1312 and unit 1. The value of failure probability after customization has been obtained of 4.22 × 10-6.

Predictors of right ventricular function as measured by tricuspid annular plane systolic excursion in heart failure

DEFF Research Database (Denmark)

Kjaergaard, Jesper; Iversen, Kasper K; Akkan, Dilek

2009-01-01

in heart failure patients, in particular with reduced septal longitudinal motion. TAPSE is decreased in patients with heart failure of ischemic etiology. However, the absolute reduction in TAPSE is small and seems to be of minor importance in the clinical utilization of TAPSE whether applied as a measure...... of right ventricular systolic function or as a prognostic factor....

Coronary flow reserve as a link between diastolic and systolic function and exercise capacity in heart failure

DEFF Research Database (Denmark)

Snoer, Martin; Monk-Hansen, Tea; Olsen, Rasmus Huan

2012-01-01

AIMS: In heart failure, a reduced exercise capacity is the prevailing symptom and an important prognostic marker of future outcome. The purpose of the study was to assess the relation of coronary flow reserve (CFR) to diastolic and systolic function in heart failure and to determine which...

Renal and cardiac function during alpha1-beta-blockade in congestive heart failure

DEFF Research Database (Denmark)

Heitmann, M; Davidsen, U; Stokholm, K H

2002-01-01

The kidney and the neurohormonal systems are essential in the pathogenesis of congestive heart failure (CHF) and the physiologic response. Routine treatment of moderate to severe CHF consists of diuretics, angiotensin-converting enzyme (ACE) inhibition and beta-blockade. The need for control...... of renal function during initiation of ACE-inhibition in patients with CHF is well known. The aim of this study was to investigate whether supplementation by a combined alpha1-beta-blockade to diuretics and ACE-inhibition might improve cardiac function without reducing renal function....

1988 failure rate screening data for fusion reliability and risk analysis

International Nuclear Information System (INIS)

Cadwallader, L.C.; Piet, S.J.

1988-01-01

This document contains failure rate screening data for application to fusion components. The screening values are generally fission or aerospace industry failure rate estimates that can be extrapolated for use by fusion system designers, reliability engineers and risk analysts. Failure rate estimates for tritium-bearing systems, liquid metal-cooled systems, gas-cooled systems, water-cooled systems and containment systems are given. Preliminary system availability estimates and selected initiating event frequency estimates are presented. This first edition document is valuable to design and safety analysis for the Compact Ignition Tokamak and the International Thermonuclear Experimental Reactor. 20 refs., 28 tabs

The prognostic importance of lung function in patients admitted with heart failure.

Science.gov (United States)

Iversen, Kasper Karmark; Kjaergaard, Jesper; Akkan, Dilek; Kober, Lars; Torp-Pedersen, Christian; Hassager, Christian; Vestbo, Jorgen; Kjoller, Erik

2010-07-01

The purpose of the present study was to determine the prognostic importance for all-cause mortality of lung function variables obtained by spirometry in an unselected group of patients admitted with heart failure (HF). This was a prospective prognostic study performed as part of the EchoCardiography and Heart Outcome Study (ECHOS). This analysis included 532 patients admitted with a clinical diagnosis of HF. All patients underwent spirometry and echocardiography and the diagnosis of HF was made according to established criteria. Mean forced expiratory volume in 1 s (FEV(1)) was 65% of the predicted value [95% confidence interval (CI) 63-67%], mean forced vital capacity (FVC) was 71% of predicted (95% CI 69-72%), and FEV(1)/FVC was 0.72 (95% CI 0.71-0.73). FEV(1), FVC, and FEV(1)/FVC were all significant prognostic factors for all-cause mortality in univariate analyses. In a multivariate analysis, FEV(1) had independent prognostic value (hazard ratio 0.86 per 10% change, P information for all-cause mortality in patients admitted with HF. Spirometry therefore seems to be worth considering for all patients admitted with HF in order to identify patients at high risk.

Application of Failure Mode and Effect Analysis (FMEA), cause and effect analysis, and Pareto diagram in conjunction with HACCP to a corn curl manufacturing plant.

Science.gov (United States)

Varzakas, Theodoros H; Arvanitoyannis, Ioannis S

2007-01-01

The Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of corn curl manufacturing. A tentative approach of FMEA application to the snacks industry was attempted in an effort to exclude the presence of GMOs in the final product. This is of crucial importance both from the ethics and the legislation (Regulations EC 1829/2003; EC 1830/2003; Directive EC 18/2001) point of view. The Preliminary Hazard Analysis and the Fault Tree Analysis were used to analyze and predict the occurring failure modes in a food chain system (corn curls processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram, and the fishbone diagram). Finally, Pareto diagrams were employed towards the optimization of GMOs detection potential of FMEA.

Phenomenological uncertainty analysis of early containment failure at severe accident of nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Lee, Su Won

2011-02-15

The severe accident has inherently significant uncertainty due to wide range of conditions and performing experiments, validation and practical application are extremely difficult because of its high temperature and pressure. Although internal and external researches were put into practice, the reference used in Korean nuclear plants were foreign data of 1980s and safety analysis as the probabilistic safety assessment has not applied the newest methodology. Also, it is applied to containment pressure formed into point value as results of thermal hydraulic analysis to identify the probability of containment failure in level 2 PSA. In this paper, the uncertainty analysis methods for phenomena of severe accident influencing early containment failure were developed, the uncertainty analysis that apply Korean nuclear plants using the MELCOR code was performed and it is a point of view to present the distribution of containment pressure as a result of uncertainty analysis. Because early containment failure is important factor of Large Early Release Frequency(LERF) that is used as representative criteria of decision-making in nuclear power plants, it was selected in this paper among various modes of containment failure. Important phenomena of early containment failure at severe accident based on previous researches were comprehended and methodology of 7th steps to evaluate uncertainty was developed. The MELCOR input for analysis of the severe accident reflected natural circulation flow was developed and the accident scenario for station black out that was representative initial event of early containment failure was determined. By reviewing the internal model and correlation for MELCOR model relevant important phenomena of early containment failure, the uncertainty factors which could affect on the uncertainty were founded and the major factors were finally identified through the sensitivity analysis. In order to determine total number of MELCOR calculations which can

Sensitivity analysis of fuel pin failure performance under slow-ramp type transient overpower condition by using a fuel performance analysis code FEMAXI-FBR

International Nuclear Information System (INIS)

Tsuboi, Yasushi; Ninokata, Hisashi; Endo, Hiroshi; Ishizu, Tomoko; Tatewaki, Isao; Saito, Hiroaki

2012-01-01

The FEMAXI-FBR is a fuel performance analysis code and has been developed as one module of core disruptive evaluation system, the ASTERIA-FBR. The FEMAXI-FBR has reproduced the failure pin behavior during slow transient overpower. The axial location of pin failure affects the power and reactivity behavior during core disruptive accident, and failure model of which pin failure occurs at upper part of pin is used by reflecting the results of the CABRI-2 test. By using the FEMAXI-FBR, sensitivity analysis of uncertainty of design parameters such as irradiation conditions and fuel fabrication tolerances was performed to clarify the effect on axial location of pin failure during slow transient overpower. The sensitivity analysis showed that the uncertainty of design parameters does not affect the failure location. It suggests that the failure model with which locations of failure occur at upper part of pin can be adopted for core disruptive calculation by taking into consideration of design uncertainties. (author)

Preliminary failure modes and effects analysis on Korean HCCR TBS to be tested in ITER

International Nuclear Information System (INIS)

Ahn, Mu-Young; Cho, Seungyon; Jin, Hyung Gon; Lee, Dong Won; Park, Yi-Hyun; Lee, Youngmin

2015-01-01

Highlights: • Postulated initiating events are identified through failure modes and effects analysis on the current HCCR TBS design. • A set of postulated initiating events are selected for consideration of deterministic analysis. • Accident evolutions on the selected postualted initiating events are qualitatively described for deterministic analysis. - Abstract: Korean Helium cooled ceramic reflector (HCCR) Test blanket system (TBS), which comprises Test blanket module (TBM) and ancillary systems in various locations of ITER building, is operated at high temperature and pressure with decay heat. Therefore, safety is utmost concern in design process and it is required to demonstrate that the HCCR TBS is designed to comply with the safety requirements and guidelines of ITER. Due to complexity of the system with many interfaces with ITER, a systematic approach is necessary for safety analysis. This paper presents preliminary failure modes and effects analysis (FMEA) study performed for the HCCR TBS. FMEA is a systematic methodology in which failure modes for components in the system and their consequences are studied from the bottom-up. Over eighty failure modes have been investigated on the HCCR TBS. The failure modes that have similar consequences are grouped as postulated initiating events (PIEs) and total seven reference accident scenarios are derived from FMEA study for deterministic accident analysis. Failure modes not covered here due to evolving design of the HCCR TBS and uncertainty in maintenance procedures will be studied further in near future.

Preliminary failure modes and effects analysis on Korean HCCR TBS to be tested in ITER

Energy Technology Data Exchange (ETDEWEB)

Ahn, Mu-Young, E-mail: myahn74@nfri.re.kr [National Fusion Research Institute, Daejeon (Korea, Republic of); Cho, Seungyon [National Fusion Research Institute, Daejeon (Korea, Republic of); Jin, Hyung Gon; Lee, Dong Won [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Park, Yi-Hyun; Lee, Youngmin [National Fusion Research Institute, Daejeon (Korea, Republic of)

2015-10-15

Highlights: • Postulated initiating events are identified through failure modes and effects analysis on the current HCCR TBS design. • A set of postulated initiating events are selected for consideration of deterministic analysis. • Accident evolutions on the selected postualted initiating events are qualitatively described for deterministic analysis. - Abstract: Korean Helium cooled ceramic reflector (HCCR) Test blanket system (TBS), which comprises Test blanket module (TBM) and ancillary systems in various locations of ITER building, is operated at high temperature and pressure with decay heat. Therefore, safety is utmost concern in design process and it is required to demonstrate that the HCCR TBS is designed to comply with the safety requirements and guidelines of ITER. Due to complexity of the system with many interfaces with ITER, a systematic approach is necessary for safety analysis. This paper presents preliminary failure modes and effects analysis (FMEA) study performed for the HCCR TBS. FMEA is a systematic methodology in which failure modes for components in the system and their consequences are studied from the bottom-up. Over eighty failure modes have been investigated on the HCCR TBS. The failure modes that have similar consequences are grouped as postulated initiating events (PIEs) and total seven reference accident scenarios are derived from FMEA study for deterministic accident analysis. Failure modes not covered here due to evolving design of the HCCR TBS and uncertainty in maintenance procedures will be studied further in near future.

Home inotropic therapy in advanced heart failure: cost analysis and clinical outcomes.

Science.gov (United States)

Harjai, K J; Mehra, M R; Ventura, H O; Lapeyre, Y M; Murgo, J P; Stapleton, D D; Smart, F W

1997-11-05

This study was conducted to assess cost savings and clinical outcomes associated with the use of home i.v. inotropic therapy in patients with advanced (New York Heart Association [NYHA] class IV) heart failure. Retrospective analysis. Tertiary care referral center. Twenty-four patients (13 men, 11 women; age, 61+/-12 years) with left ventricular ejection fraction home i.v. inotropic therapy for at least 4 consecutive weeks between May 1994 and April 1996. Inotropic agents used included dobutamine (n=20; dose, 5.0+/-2.2 microg/kg/min) or milrinone (n=7; dose, 0.53+/-0.05 microg/kg/min). Cost of care and clinical outcomes (hospital admissions, length of hospital stay, NYHA functional class) were compared during the period of inotropic therapy (study period) and the immediate preceding period of equal duration (control period). In comparison to the control period, the study period (3.9+/-2.7 months) was associated with a 16% reduction in cost, amounting to a calculated savings of $5,700 per patient or $1,465 per patient per month. Concomitantly, a decrease in the number of hospital admissions from 2.7+/-2.6 to 1.3+/-1.3 (p=0.056) and length of hospital stay from 20.9+/-12.7 to 5.5+/-5.4 days (p=0.0004) was observed with improvement in NYHA functional class from 4.0+/-0.0 to 2.7+/-0.9 (phome i.v. inotropic therapy. Home i.v. inotropic therapy reduces hospital admissions, length of stay, and cost of care and improves functional class in patients with advanced (NYHA class IV) heart failure.

Development of a container failure function for titanium

International Nuclear Information System (INIS)

Ikeda, B.M.; Shoesmith, D.W.

1990-01-01

Any prediction of container failure times will be based on measurements of crevice corrosion rates under conditions that simulate those anticipated in a waste vault. Since there is a good mechanistic understanding of crevice corrosion in titanium alloys, this is a reasonable approach. Some containers are assumed to fail immediately because of undetected fabrication defects. Experiments designed to measure corrosion penetration rates are under way. Uniform corrosion rates will be determined from weight-gain measurements and estimated from measurements of oxide thickness using Auger spectroscopy. Crevice corrosion can be estimated by counting the number of pits and corroded areas within the crevice using an image analyzer. By performing such analyses on a wide range of specimens under a variety of conditions the authors hope to determine the susceptibilities of titanium alloys to crevice corrosion; measure the uniform and crevice corrosion rates as a function of temperature and chloride concentration; measure the extent of hydrogen pickup as a function of temperature and chloride concentration; and predict the lifetime of containers under Canadian waste vault conditions

Metallic ureteral stents in malignant ureteral obstruction: clinical factors predicting stent failure.

Science.gov (United States)

Chow, Po-Ming; Hsu, Jui-Shan; Huang, Chao-Yuan; Wang, Shuo-Meng; Lee, Yuan-Ju; Huang, Kuo-How; Yu, Hong-Jheng; Pu, Yeong-Shiau; Liang, Po-Chin

2014-06-01

To provide clinical outcomes of the Resonance metallic ureteral stent in patients with malignant ureteral obstruction, as well as clinical factors predicting stent failure. Cancer patients who have received Resonance stents from July 2009 to March 2012 for ureteral obstruction were included for chart review. Stent failure was detected by clinical symptoms, image studies, and renal function tests. Survival analysis for stent duration was used to estimate patency rate and factors predicting stent failure. A total of 117 stents were inserted successfully into 94 ureteral units in 79 patients. There were no major complications. These stents underwent survival analysis and proportional hazard regression. The median duration for the stents was 5.77 months. In multivariate analysis, age (P=0.043), preoperative serum creatinine level (P=0.0174), and cancer type (P=0.0494) were significant factors associated with stent failure. Cancer treatment before and after stent insertion had no effect on stent duration. Resonance stents are effective and safe in relieving malignant ureteral obstructions. Old age and high serum creatinine level are predictors for stent failure. Stents in patients with lower gastrointestinal cancers have longer functional duration.

An analysis of human maintenance failures of a nuclear power plant

International Nuclear Information System (INIS)

Pyy, P.

2000-01-01

In the report, a study of faults caused by maintenance activities is presented. The objective of the study was to draw conclusions on the unplanned effects of maintenance on nuclear power plant safety and system availability. More than 4400 maintenance history reports from the years 1992-1994 of Olkiluoto BWR nuclear power plant (NPP) were analysed together with the maintenance personnel. The human action induced faults were classified, e.g., according to their multiplicity and effects. This paper presents and discusses the results of a statistical analysis of the data. Instrumentation and electrical components appeared to be especially prone to human failures. Many human failures were found in safety related systems. Several failures also remained latent from outages to power operation. However, the safety significance of failures was generally small. Modifications were an important source of multiple human failures. Plant maintenance data is a good source of human reliability data and it should be used more in the future. (orig.)

Local buckling failure analysis of high-strength pipelines

Institute of Scientific and Technical Information of China (English)

Yan Li; Jian Shuai; Zhong-Li Jin; Ya-Tong Zhao; Kui Xu

2017-01-01

Pipelines in geological disaster regions typically suffer the risk of local buckling failure because of slender structure and complex load.This paper is meant to reveal the local buckling behavior of buried pipelines with a large diameter and high strength,which are under different conditions,including pure bending and bending combined with internal pressure.Finite element analysis was built according to previous data to study local buckling behavior of pressurized and unpressurized pipes under bending conditions and their differences in local buckling failure modes.In parametric analysis,a series of parameters,including pipe geometrical dimension,pipe material properties and internal pressure,were selected to study their influences on the critical bending moment,critical compressive stress and critical compressive strain of pipes.Especially the hardening exponent of pipe material was introduced to the parameter analysis by using the Ramberg-Osgood constitutive model.Results showed that geometrical dimensions,material and internal pressure can exert similar effects on the critical bending moment and critical compressive stress,which have different,even reverse effects on the critical compressive strain.Based on these analyses,more accurate design models of critical bending moment and critical compressive stress have been proposed for high-strength pipelines under bending conditions,which provide theoretical methods for highstrength pipeline engineering.

Recognition and Analysis of Corrosion Failure Mechanisms

OpenAIRE

Steven Suess

2006-01-01

Corrosion has a vast impact on the global and domestic economy, and currently incurs losses of nearly $300 billion annually to the U.S. economy alone. Because of the huge impact of corrosion, it is imperative to have a systematic approach to recognizing and mitigating corrosion problems as soon as possible after they become apparent. A proper failure analysis includes collection of pertinent background data and service history, followed by visual inspection, photographic documentation, materi...

Comparison of Failure Analysis and Operating Experiences of Digital Control Systems

Energy Technology Data Exchange (ETDEWEB)

Lee, Eun Chan; Shin, Tae Young [Korea Hydro and Nuclear Power Co., Daejeon (Korea, Republic of)

2014-08-15

This study focuses on digital control systems that have the same functions but different designs. Some differences and common points between these two digital control systems are analyzed in terms of vulnerabilities in plant operation. In addition, this study confirms why unexpected outcomes can occur through a comparison of the system failure experiences with the analytic results of FMEA and FTA. This evaluation demonstrates that the digital system may have vulnerable components whose single failures can cause plant transients even if the system has a redundant structure according to its system design.

Analysis of risk factors for cluster behavior of dental implant failures.

Science.gov (United States)

Chrcanovic, Bruno Ramos; Kisch, Jenö; Albrektsson, Tomas; Wennerberg, Ann

2017-08-01

Some studies indicated that implant failures are commonly concentrated in few patients. To identify and analyze cluster behavior of dental implant failures among subjects of a retrospective study. This retrospective study included patients receiving at least three implants only. Patients presenting at least three implant failures were classified as presenting a cluster behavior. Univariate and multivariate logistic regression models and generalized estimating equations analysis evaluated the effect of explanatory variables on the cluster behavior. There were 1406 patients with three or more implants (8337 implants, 592 failures). Sixty-seven (4.77%) patients presented cluster behavior, with 56.8% of all implant failures. The intake of antidepressants and bruxism were identified as potential negative factors exerting a statistically significant influence on a cluster behavior at the patient-level. The negative factors at the implant-level were turned implants, short implants, poor bone quality, age of the patient, the intake of medicaments to reduce the acid gastric production, smoking, and bruxism. A cluster pattern among patients with implant failure is highly probable. Factors of interest as predictors for implant failures could be a number of systemic and local factors, although a direct causal relationship cannot be ascertained. © 2017 Wiley Periodicals, Inc.

Detecting failure events in buildings: a numerical and experimental analysis

OpenAIRE

Heckman, V. M.; Kohler, M. D.; Heaton, T. H.

2010-01-01

A numerical method is used to investigate an approach for detecting the brittle fracture of welds associated with beam -column connections in instrumented buildings in real time through the use of time-reversed Green’s functions and wave propagation reciprocity. The approach makes use of a prerecorded catalog of Green’s functions for an instrumented building to detect failure events in the building during a later seismic event by screening continuous data for the presence of wavef...

Corrosion failure analysis as related to prevention of corrosion failures

International Nuclear Information System (INIS)

Suss, H.

1977-10-01

The factors and conditions which have contributed to many of the corrosion related service failures are discussed based on a review of actual case histories. The anti-corrosion devices which developed as a result of these failure analyses are reviewed, and the method which must be adopted and used to take advantage of the available corrosion prevention techniques is discussed

Failure probability analysis on mercury target vessel

International Nuclear Information System (INIS)

Ishikura, Syuichi; Futakawa, Masatoshi; Kogawa, Hiroyuki; Sato, Hiroshi; Haga, Katsuhiro; Ikeda, Yujiro

2005-03-01

Failure probability analysis was carried out to estimate the lifetime of the mercury target which will be installed into the JSNS (Japan spallation neutron source) in J-PARC (Japan Proton Accelerator Research Complex). The lifetime was estimated as taking loading condition and materials degradation into account. Considered loads imposed on the target vessel were the static stresses due to thermal expansion and static pre-pressure on He-gas and mercury and the dynamic stresses due to the thermally shocked pressure waves generated repeatedly at 25 Hz. Materials used in target vessel will be degraded by the fatigue, neutron and proton irradiation, mercury immersion and pitting damages, etc. The imposed stresses were evaluated through static and dynamic structural analyses. The material-degradations were deduced based on published experimental data. As a result, it was quantitatively confirmed that the failure probability for the lifetime expected in the design is very much lower, 10 -11 in the safety hull, meaning that it will be hardly failed during the design lifetime. On the other hand, the beam window of mercury vessel suffered with high-pressure waves exhibits the failure probability of 12%. It was concluded, therefore, that the leaked mercury from the failed area at the beam window is adequately kept in the space between the safety hull and the mercury vessel by using mercury-leakage sensors. (author)

Dam failure analysis for the Lago El Guineo Dam, Orocovis, Puerto Rico

Science.gov (United States)

Gómez-Fragoso, Julieta; Heriberto Torres-Sierra,

2016-08-09

The U.S. Geological Survey, in cooperation with the Puerto Rico Electric Power Authority, completed hydrologic and hydraulic analyses to assess the potential hazard to human life and property associated with the hypothetical failure of the Lago El Guineo Dam. The Lago El Guineo Dam is within the headwaters of the Río Grande de Manatí and impounds a drainage area of about 4.25 square kilometers.The hydrologic assessment was designed to determine the outflow hydrographs and peak discharges for Lago El Guineo and other subbasins in the Río Grande de Manatí hydrographic basin for three extreme rainfall events: (1) a 6-hour probable maximum precipitation event, (2) a 24-hour probable maximum precipitation event, and (3) a 24-hour, 100-year recurrence rainfall event. The hydraulic study simulated a dam failure of Lago El Guineo Dam using flood hydrographs generated from the hydrologic study. The simulated dam failure generated a hydrograph that was routed downstream from Lago El Guineo Dam through the lower reaches of the Río Toro Negro and the Río Grande de Manatí to determine water-surface profiles developed from the event-based hydrologic scenarios and “sunny day” conditions. The Hydrologic Engineering Center’s Hydrologic Modeling System (HEC–HMS) and Hydrologic Engineering Center’s River Analysis System (HEC–RAS) computer programs, developed by the U.S. Army Corps of Engineers, were used for the hydrologic and hydraulic modeling, respectively. The flow routing in the hydraulic analyses was completed using the unsteady flow module available in the HEC–RAS model.Above the Lago El Guineo Dam, the simulated inflow peak discharges from HEC–HMS resulted in about 550 and 414 cubic meters per second for the 6- and 24-hour probable maximum precipitation events, respectively. The 24-hour, 100-year recurrence storm simulation resulted in a peak discharge of about 216 cubic meters per second. For the hydrologic analysis, no dam failure conditions are

Risk assessment of the emergency processes: Healthcare failure mode and effect analysis.

Science.gov (United States)

Taleghani, Yasamin Molavi; Rezaei, Fatemeh; Sheikhbardsiri, Hojat

2016-01-01

Ensuring about the patient's safety is the first vital step in improving the quality of care and the emergency ward is known as a high-risk area in treatment health care. The present study was conducted to evaluate the selected risk processes of emergency surgery department of a treatment-educational Qaem center in Mashhad by using analysis method of the conditions and failure effects in health care. In this study, in combination (qualitative action research and quantitative cross-sectional), failure modes and effects of 5 high-risk procedures of the emergency surgery department were identified and analyzed according to Healthcare Failure Mode and Effects Analysis (HFMEA). To classify the failure modes from the "nursing errors in clinical management model (NECM)", the classification of the effective causes of error from "Eindhoven model" and determination of the strategies to improve from the "theory of solving problem by an inventive method" were used. To analyze the quantitative data of descriptive statistics (total points) and to analyze the qualitative data, content analysis and agreement of comments of the members were used. In 5 selected processes by "voting method using rating", 23 steps, 61 sub-processes and 217 potential failure modes were identified by HFMEA. 25 (11.5%) failure modes as the high risk errors were detected and transferred to the decision tree. The most and the least failure modes were placed in the categories of care errors (54.7%) and knowledge and skill (9.5%), respectively. Also, 29.4% of preventive measures were in the category of human resource management strategy. "Revision and re-engineering of processes", "continuous monitoring of the works", "preparation and revision of operating procedures and policies", "developing the criteria for evaluating the performance of the personnel", "designing a suitable educational content for needs of employee", "training patients", "reducing the workload and power shortage", "improving team

Development of severe accident analysis code - Development of a finite element code for lower head failure analysis

Energy Technology Data Exchange (ETDEWEB)

Huh, Hoon; Lee, Choong Ho; Choi, Tae Hoon; Kim, Hyun Sup; Kim, Se Ho; Kang, Woo Jong; Seo, Chong Kwan [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

1995-08-01

The study concerns the development of analysis models and computer codes for lower head failure analysis when a severe accident occurs in a nuclear reactor system. Although the lower head failure modes consists of several failure modes, the study this year was focused on the global rupture with the collapse pressure and mode by limit analysis and elastic deformation. The behavior of molten core causes elevation of temperature in the reactor vessel wall and deterioration of load-carrying capacity of a reactor vessel. The behavior of molten core and the heat transfer modes were, therefore, postulated in several types and the temperature distributions according to the assumed heat flux modes were calculated. The collapse pressure of a nuclear reactor lower head decreases rapidly with elevation of temperature as time passes. The calculation shows the safety of a nuclear reactor is enhanced with the lager collapse pressure when the hot spot is located far from the pole. 42 refs., 2 tabs., 31 figs. (author)

American Heart Association's Life's Simple 7: Avoiding Heart Failure and Preserving Cardiac Structure and Function.

Science.gov (United States)

Folsom, Aaron R; Shah, Amil M; Lutsey, Pamela L; Roetker, Nicholas S; Alonso, Alvaro; Avery, Christy L; Miedema, Michael D; Konety, Suma; Chang, Patricia P; Solomon, Scott D

2015-09-01

Many people may underappreciate the role of lifestyle in avoiding heart failure. We estimated whether greater adherence in middle age to American Heart Association's Life's Simple 7 guidelines—on smoking, body mass, physical activity, diet, cholesterol, blood pressure, and glucose—is associated with lower lifetime risk of heart failure and greater preservation of cardiac structure and function in old age. We studied the population-based Atherosclerosis Risk in Communities Study cohort of 13,462 adults ages 45-64 years in 1987-1989. From the 1987-1989 risk factor measurements, we created a Life's Simple 7 score (range 0-14, giving 2 points for ideal, 1 point for intermediate, and 0 points for poor components). We identified 2218 incident heart failure events using surveillance of hospital discharge and death codes through 2011. In addition, in 4855 participants free of clinical cardiovascular disease in 2011-2013, we performed echocardiography from which we quantified left ventricular hypertrophy and diastolic dysfunction. One in four participants (25.5%) developed heart failure through age 85 years. Yet, this lifetime heart failure risk was 14.4% for those with a middle-age Life's Simple 7 score of 10-14 (optimal), 26.8% for a score of 5-9 (average), and 48.6% for a score of 0-4 (inadequate). Among those with no clinical cardiovascular event, the prevalence of left ventricular hypertrophy in late life was approximately 40% as common, and diastolic dysfunction was approximately 60% as common, among those with an optimal middle-age Life's Simple 7 score, compared with an inadequate score. Greater achievement of American Heart Association's Life's Simple 7 in middle age is associated with a lower lifetime occurrence of heart failure and greater preservation of cardiac structure and function. Copyright © 2015 Elsevier Inc. All rights reserved.

[Examination of safety improvement by failure record analysis that uses reliability engineering].

Science.gov (United States)

Kato, Kyoichi; Sato, Hisaya; Abe, Yoshihisa; Ishimori, Yoshiyuki; Hirano, Hiroshi; Higashimura, Kyoji; Amauchi, Hiroshi; Yanakita, Takashi; Kikuchi, Kei; Nakazawa, Yasuo

2010-08-20

How the maintenance checks of the medical treatment system, including start of work check and the ending check, was effective for preventive maintenance and the safety improvement was verified. In this research, date on the failure of devices in multiple facilities was collected, and the data of the trouble repair record was analyzed by the technique of reliability engineering. An analysis of data on the system (8 general systems, 6 Angio systems, 11 CT systems, 8 MRI systems, 8 RI systems, and the radiation therapy system 9) used in eight hospitals was performed. The data collection period assumed nine months from April to December 2008. Seven items were analyzed. (1) Mean time between failures (MTBF) (2) Mean time to repair (MTTR) (3) Mean down time (MDT) (4) Number found by check in morning (5) Failure generation time according to modality. The classification of the breakdowns per device, the incidence, and the tendency could be understood by introducing reliability engineering. Analysis, evaluation, and feedback on the failure generation history are useful to keep downtime to a minimum and to ensure safety.

Statistical trend analysis methodology for rare failures in changing technical systems

International Nuclear Information System (INIS)

Ott, K.O.; Hoffmann, H.J.

1983-07-01

A methodology for a statistical trend analysis (STA) in failure rates is presented. It applies primarily to relatively rare events in changing technologies or components. The formulation is more general and the assumptions are less restrictive than in a previously published version. Relations of the statistical analysis and probabilistic assessment (PRA) are discussed in terms of categorization of decisions for action following particular failure events. The significance of tentatively identified trends is explored. In addition to statistical tests for trend significance, a combination of STA and PRA results quantifying the trend complement is proposed. The STA approach is compared with other concepts for trend characterization. (orig.)

Adaptation to periodic pressure chamber hypoxia and its influence on systolic and diastolic functions in chronic heart failure

Directory of Open Access Journals (Sweden)

Dmitrieva М.К.

2012-06-01

Full Text Available Research objective is to determine the influence of adaptation method to periodic pressure chamber hypoxia on dynamics of systolic and diastolic functions of myocardium in patients with early stages of chronic heart failure. Materials and Methods: 100 men with post-infarction cardiosclerosis at the age of 40-65 years with I and IIA stages and l-ll functional classes (NYHA of chronic heart failure have been examined. Results: Positive dynamics of systolic and diastolic cardiac functions and other parameters of echocardioscopy under the influence of the hypoxic therapy in comparison with classical physical rehabilitation have been obtained. Furthermore, a more significant effect has been observed in patients with CHF IIA. Conclusion: Improvement in the geometry of the heart has proved that adaptation method to periodic pressure chamber hypoxia could be recommended for rehabilitation of patients with heart failure of early stages.

Distributed analysis functional testing using GangaRobot in the ATLAS experiment

Science.gov (United States)

Legger, Federica; ATLAS Collaboration

2011-12-01

Automated distributed analysis tests are necessary to ensure smooth operations of the ATLAS grid resources. The HammerCloud framework allows for easy definition, submission and monitoring of grid test applications. Both functional and stress test applications can be defined in HammerCloud. Stress tests are large-scale tests meant to verify the behaviour of sites under heavy load. Functional tests are light user applications running at each site with high frequency, to ensure that the site functionalities are available at all times. Success or failure rates of these tests jobs are individually monitored. Test definitions and results are stored in a database and made available to users and site administrators through a web interface. In this work we present the recent developments of the GangaRobot framework. GangaRobot monitors the outcome of functional tests, creates a blacklist of sites failing the tests, and exports the results to the ATLAS Site Status Board (SSB) and to the Service Availability Monitor (SAM), providing on the one hand a fast way to identify systematic or temporary site failures, and on the other hand allowing for an effective distribution of the work load on the available resources.

Application of failure mode and effect analysis in an assisted reproduction technology laboratory.

Science.gov (United States)

Intra, Giulia; Alteri, Alessandra; Corti, Laura; Rabellotti, Elisa; Papaleo, Enrico; Restelli, Liliana; Biondo, Stefania; Garancini, Maria Paola; Candiani, Massimo; Viganò, Paola

2016-08-01

Assisted reproduction technology laboratories have a very high degree of complexity. Mismatches of gametes or embryos can occur, with catastrophic consequences for patients. To minimize the risk of error, a multi-institutional working group applied failure mode and effects analysis (FMEA) to each critical activity/step as a method of risk assessment. This analysis led to the identification of the potential failure modes, together with their causes and effects, using the risk priority number (RPN) scoring system. In total, 11 individual steps and 68 different potential failure modes were identified. The highest ranked failure modes, with an RPN score of 25, encompassed 17 failures and pertained to "patient mismatch" and "biological sample mismatch". The maximum reduction in risk, with RPN reduced from 25 to 5, was mostly related to the introduction of witnessing. The critical failure modes in sample processing were improved by 50% in the RPN by focusing on staff training. Three indicators of FMEA success, based on technical skill, competence and traceability, have been evaluated after FMEA implementation. Witnessing by a second human operator should be introduced in the laboratory to avoid sample mix-ups. These findings confirm that FMEA can effectively reduce errors in assisted reproduction technology laboratories. Copyright © 2016 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.

Modeling of fast reactor cladding failure for hypothetical accident transient analysis

International Nuclear Information System (INIS)

Kramer, J.M.; DiMelfi, R.J.; Hughes, T.H.; Deitrich, L.W.

1979-01-01

An analysis is made of burst experiments performed on neutron irradiated cladding tubes. This is done by employing a generalized Voce equation to describe the mechanical deformation of type 316 stainless steel, combined with an empirical creep crack growth law, each modified to account for the effects of irradiation matrix hardening, and irradiation induced grain boundary embrittlement, respectively. The results of this analysis indicate that for large initial hoop stress, failure occurs at relatively low temperature and is controlled by the onset of plastic instability. The increase in failure temperature of irradiated material, in this low temperature region, is due to irradiation strengthening. Failure in the case of relatively small initial hoop stress occurs at high temperature where the Voce equation reduces to a power law creep formula. The ductility of irradiated material, in this high temperature region, is adequately described through the use of an empirical intergranular crack growth law used in conjunction with the creep law. The effect of neutron irradiation is to reduce the activation energy for crack propagation from the value for creep to some lower value correlated to independent Dorn rupture parameter measurements. The result is a predicted reduced ductility which translates into a reduction in failure temperature at a given hoop stress value for irradiated material. (orig.)

Elastic-plastic failure analysis of pressure burst tests of thin toroidal shells

International Nuclear Information System (INIS)

Jones, D.P.; Holliday, J.E.; Larson, L.D.

1998-07-01

This paper provides a comparison between test and analysis results for bursting of thin toroidal shells. Testing was done by pressurizing two toroidal shells until failure by bursting. An analytical criterion for bursting is developed based on good agreement between structural instability predicted by large strain-large displacement elastic-plastic finite element analysis and observed burst pressure obtained from test. The failures were characterized by loss of local stability of the membrane section of the shells consistent with the predictions from the finite element analysis. Good agreement between measured and predicted burst pressure suggests that incipient structural instability as calculated by an elastic-plastic finite element analysis is a reasonable way to calculate the bursting pressure of thin membrane structures

Failure analysis of carbide fuels under transient overpower (TOP) conditions

International Nuclear Information System (INIS)

Nguyen, D.H.

1980-06-01

The failure of carbide fuels in the Fast Test Reactor (FTR) under Transient Overpower (TOP) conditions has been examined. The Beginning-of-Cycle Four (BOC-4) all-oxide base case, at $.50/sec ramp rate was selected as the reference case. A coupling between the advanced fuel performance code UNCLE-T and HCDA Code MELT-IIIA was necessary for the analysis. UNCLE-T was used to determine cladding failure and fuel preconditioning which served as initial conditions for MELT-III calculations. MELT-IIIA determined the time of molten fuel ejection from fuel pin

Transient acute renal failure and functional hemispheric depression after cerebral arteriography in diabetic patients

DEFF Research Database (Denmark)

Olsen, Tom Skyhøj; Lund, P; Praestholm, J

1981-01-01

Cerebral angiography was carried out in two diabetic patients in the evaluation of minor vascular ischemic episodes. A transient acute renal failure following cerebral angiography was accompanied by a transient comatose episode with severe unilateral neurological deficits. A functional depression...

Failure analysis of boiler tubes in lakhra coal power plant

International Nuclear Information System (INIS)

Shah, A.; Baluch, M.M.; Ali, A.

2010-01-01

Present work deals with the failure analysis of a boiler tube in Lakhra fluidized bed combustion power station. Initially, visual inspection technique was adopted to analyse the fractured surface. Detailed microstructural investigations of the busted boiler tube were carried out using light optical microscope and scanning electron microscope. The hardness tests were also performed. A 50 percent decrease in hardness of intact portion of the tube material and from area adjacent to failure was measured, which was found to be in good agreement with the wall thicknesses measured of the busted boiler tube i.e. 4 mm and 2 mm from unaffected portion and ruptured area respectively. It was concluded that the major cause of failure of boiler tube is erosion of material which occurs due the coal particles strike at the surface of the tube material. Since the temperature of boiler is not maintained uniformly. The variations in boiler temperature can also affect the material and could be another reason for the failure of the tube. (author)

[Retrieval and failure analysis of surgical implants in Brazil: the need for proper regulation].

Science.gov (United States)

Azevedo, Cesar R de Farias; Hippert, Eduardo

2002-01-01

This paper summarizes several cases of metallurgical failure analysis of surgical implants conducted at the Laboratory of Failure Analysis, Instituto de Pesquisas Tecnológicas (IPT), in Brazil. Failures with two stainless steel femoral compression plates, one stainless steel femoral nail plate, one Ti-6Al-4V alloy maxillary reconstruction plate, and five Nitinol wires were investigated. The results showed that the implants were not in accordance with ISO standards and presented evidence of corrosion-assisted fracture. Furthermore, some of the implants presented manufacturing/processing defects which also contributed to their premature failure. Implantation of materials that are not biocompatible may cause several types of adverse effects in the human body and lead to premature implant failure. A review of prevailing health legislation is needed in Brazil, along with the adoption of regulatory mechanisms to assure the quality of surgical implants on the market, providing for compulsory procedures in the reporting and investigation of surgical implants which have failed in service.

Failure mode and effects analysis outputs: are they valid?

Science.gov (United States)

Shebl, Nada Atef; Franklin, Bryony Dean; Barber, Nick

2012-06-10

Failure Mode and Effects Analysis (FMEA) is a prospective risk assessment tool that has been widely used within the aerospace and automotive industries and has been utilised within healthcare since the early 1990s. The aim of this study was to explore the validity of FMEA outputs within a hospital setting in the United Kingdom. Two multidisciplinary teams each conducted an FMEA for the use of vancomycin and gentamicin. Four different validity tests were conducted: Face validity: by comparing the FMEA participants' mapped processes with observational work. Content validity: by presenting the FMEA findings to other healthcare professionals. Criterion validity: by comparing the FMEA findings with data reported on the trust's incident report database. Construct validity: by exploring the relevant mathematical theories involved in calculating the FMEA risk priority number. Face validity was positive as the researcher documented the same processes of care as mapped by the FMEA participants. However, other healthcare professionals identified potential failures missed by the FMEA teams. Furthermore, the FMEA groups failed to include failures related to omitted doses; yet these were the failures most commonly reported in the trust's incident database. Calculating the RPN by multiplying severity, probability and detectability scores was deemed invalid because it is based on calculations that breach the mathematical properties of the scales used. There are significant methodological challenges in validating FMEA. It is a useful tool to aid multidisciplinary groups in mapping and understanding a process of care; however, the results of our study cast doubt on its validity. FMEA teams are likely to need different sources of information, besides their personal experience and knowledge, to identify potential failures. As for FMEA's methodology for scoring failures, there were discrepancies between the teams' estimates and similar incidents reported on the trust's incident

Structures for common-cause failure analysis

International Nuclear Information System (INIS)

Vaurio, J.K.

1981-01-01

Common-cause failure methodology and terminology have been reviewed and structured to provide a systematical basis for addressing and developing models and methods for quantification. The structure is based on (1) a specific set of definitions, (2) categories based on the way faults are attributable to a common cause, and (3) classes based on the time of entry and the time of elimination of the faults. The failure events are then characterized by their likelihood or frequency and the average residence time. The structure provides a basis for selecting computational models, collecting and evaluating data and assessing the importance of various failure types, and for developing effective defences against common-cause failure. The relationships of this and several other structures are described

Health Literacy and Global Cognitive Function Predict E-Mail but Not Internet Use in Heart Failure Patients

Directory of Open Access Journals (Sweden)

Jared P. Schprechman

2013-01-01

Full Text Available Background. The internet offers a potential for improving patient knowledge, and e-mail may be used in patient communication with providers. However, barriers to internet and e-mail use, such as low health literacy and cognitive impairment, may prevent patients from using technological resources. Purpose. We investigated whether health literacy, heart failure knowledge, and cognitive function were related to internet and e-mail use in older adults with heart failure (HF. Methods. Older adults (N=119 with heart failure (69.84±9.09 years completed measures of health literacy, heart failure knowledge, cognitive functioning, and internet use in a cross-sectional study. Results. Internet and e-mail use were reported in 78.2% and 71.4% of this sample of patients with HF, respectively. Controlling for age and education, logistic regression analyses indicated that higher health literacy predicted e-mail (P<.05 but not internet use. Global cognitive function predicted e-mail (P<.05 but not internet use. Only 45% used the Internet to obtain information on HF and internet use was not associated with greater HF knowledge. Conclusions. The majority of HF patients use the internet and e-mail, but poor health literacy and cognitive impairment may prevent some patients from accessing these resources. Future studies that examine specific internet and email interventions to increase HF knowledge are needed.

Diuretics as pathogenetic treatment for heart failure

Science.gov (United States)

Guglin, Maya

2011-01-01

Increased intracardiac filling pressure or congestion causes symptoms and leads to hospital admissions in patients with heart failure, regardless of their systolic function. A history of hospital admission, in turn, predicts further hospitalizations and morbidity, and a higher number of hospitalizations determine higher mortality. Congestion is therefore the driving force of the natural history of heart failure. Congestion is the syndrome shared by heart failure with preserved and reduced systolic function. These two conditions have almost identical morbidity, mortality, and survival because the outcomes are driven by congestion. A small difference in favor of heart failure with preserved systolic function comes from decreased ejection fraction and left ventricular remodeling which is only present in heart failure with decreased systolic function. The magnitude of this difference reflects the contribution of decreased systolic function and ventricular remodeling to the progression of heart failure. The only treatment available for congestion is fluid removal via diuretics, ultrafiltration, or dialysis. It is the only treatment that works equally well for heart failure with reduced and preserved systolic function because it affects congestion, the main pathogenetic feature of the disease. Diuretics are pathogenetic therapy for heart failure. PMID:21403798

ANALYSIS OF RELIABILITY OF NONRECTORABLE REDUNDANT POWER SYSTEMS TAKING INTO ACCOUNT COMMON FAILURES

Directory of Open Access Journals (Sweden)

V. A. Anischenko

2014-01-01

Full Text Available Reliability Analysis of nonrestorable redundant power Systems of industrial plants and other consumers of electric energy was carried out. The main attention was paid to numbers failures influence, caused by failures of all elements of System due to one general reason. Noted the main possible reasons of common failures formation. Two main indicators of reliability of non-restorable systems are considered: average time of no-failure operation and mean probability of no-failure operation. Modeling of failures were carried out by mean of division of investigated system into two in-series connected subsystems, one of them indicated independent failures, but the other indicated common failures. Due to joined modeling of single and common failures resulting intensity of failures is the amount incompatible components: intensity statistically independent failures and intensity of common failures of elements and system in total.It is shown the influence of common failures of elements on average time of no-failure operation of system. There is built the scale of preference of systems according to criterion of  average time maximum of no-failure operation, depending on portion of common failures. It is noticed that such common failures don’t influence on the scale of preference, but  change intervals of time, determining the moments of systems failures and excepting them from the number of comparators. There were discussed two problems  of conditionally optimization of  systems’  reservation choice, taking into account their reliability and cost. The first problem is solved due to criterion of minimum cost of system providing mean probability of no-failure operation, the second problem is solved due to criterion of maximum of mean probability of no-failure operation with cost limitation of system.

Quantification of a decision-making failure probability of the accident management using cognitive analysis model

Energy Technology Data Exchange (ETDEWEB)

Yoshida, Yoshitaka; Ohtani, Masanori [Institute of Nuclear Safety System, Inc., Mihama, Fukui (Japan); Fujita, Yushi [TECNOVA Corp., Tokyo (Japan)

2002-09-01

In the nuclear power plant, much knowledge is acquired through probabilistic safety assessment (PSA) of a severe accident, and accident management (AM) is prepared. It is necessary to evaluate the effectiveness of AM using the decision-making failure probability of an emergency organization, operation failure probability of operators, success criteria of AM and reliability of AM equipments in PSA. However, there has been no suitable qualification method for PSA so far to obtain the decision-making failure probability, because the decision-making failure of an emergency organization treats the knowledge based error. In this work, we developed a new method for quantification of the decision-making failure probability of an emergency organization using cognitive analysis model, which decided an AM strategy, in a nuclear power plant at the severe accident, and tried to apply it to a typical pressurized water reactor (PWR) plant. As a result: (1) It could quantify the decision-making failure probability adjusted to PSA for general analysts, who do not necessarily possess professional human factors knowledge, by choosing the suitable value of a basic failure probability and an error-factor. (2) The decision-making failure probabilities of six AMs were in the range of 0.23 to 0.41 using the screening evaluation method and in the range of 0.10 to 0.19 using the detailed evaluation method as the result of trial evaluation based on severe accident analysis of a typical PWR plant, and a result of sensitivity analysis of the conservative assumption, failure probability decreased about 50%. (3) The failure probability using the screening evaluation method exceeded that using detailed evaluation method by 99% of probability theoretically, and the failure probability of AM in this study exceeded 100%. From this result, it was shown that the decision-making failure probability was more conservative than the detailed evaluation method, and the screening evaluation method satisfied

Quantification of a decision-making failure probability of the accident management using cognitive analysis model

International Nuclear Information System (INIS)

Yoshida, Yoshitaka; Ohtani, Masanori; Fujita, Yushi

2002-01-01

In the nuclear power plant, much knowledge is acquired through probabilistic safety assessment (PSA) of a severe accident, and accident management (AM) is prepared. It is necessary to evaluate the effectiveness of AM using the decision-making failure probability of an emergency organization, operation failure probability of operators, success criteria of AM and reliability of AM equipments in PSA. However, there has been no suitable qualification method for PSA so far to obtain the decision-making failure probability, because the decision-making failure of an emergency organization treats the knowledge based error. In this work, we developed a new method for quantification of the decision-making failure probability of an emergency organization using cognitive analysis model, which decided an AM strategy, in a nuclear power plant at the severe accident, and tried to apply it to a typical pressurized water reactor (PWR) plant. As a result: (1) It could quantify the decision-making failure probability adjusted to PSA for general analysts, who do not necessarily possess professional human factors knowledge, by choosing the suitable value of a basic failure probability and an error-factor. (2) The decision-making failure probabilities of six AMs were in the range of 0.23 to 0.41 using the screening evaluation method and in the range of 0.10 to 0.19 using the detailed evaluation method as the result of trial evaluation based on severe accident analysis of a typical PWR plant, and a result of sensitivity analysis of the conservative assumption, failure probability decreased about 50%. (3) The failure probability using the screening evaluation method exceeded that using detailed evaluation method by 99% of probability theoretically, and the failure probability of AM in this study exceeded 100%. From this result, it was shown that the decision-making failure probability was more conservative than the detailed evaluation method, and the screening evaluation method satisfied

The Impact of Family Functioning on Caregiver Burden among Caregivers of Veterans with Congestive Heart Failure

Science.gov (United States)

Moore, Crystal Dea

2010-01-01

A cross-sectional study of 76 family caregivers of older veterans with congestive heart failure utilized the McMaster model of family functioning to examine the impact of family functioning variables (problem solving, communication, roles, affective responsiveness, and affective involvement) on caregiver burden dimensions (relationship burden,…

Safety Management in an Oil Company through Failure Mode Effects and Critical Analysis

Directory of Open Access Journals (Sweden)

Benedictus Rahardjo

2016-06-01

Full Text Available This study attempts to apply Failure Mode Effects and Criticality Analysis (FMECA to improve the safety of a production system, specifically the production process of an oil company. Since food processing is a worldwide issue and self-management of a food company is more important than relying on government regulations, therefore this study focused on that matter. The initial step of this study is to identify and analyze the criticality of the potential failure modes of the production process. Furthermore, take corrective action to minimize the probability of repeating the same failure mode, followed by a re-analysis of its criticality. The results of corrective actions were compared with those before improvement conditions by testing the significance of the difference using two sample t-test. The final measured result is the Criticality Priority Number (CPN, which refers to the severity category of the failure mode and the probability of occurrence of the same failure mode. The recommended actions proposed by the FMECA significantly reduce the CPN compared with the value before improvement, with increases of 38.46% for the palm olein case study.

Functional analysis

CERN Document Server

Kantorovich, L V

1982-01-01

Functional Analysis examines trends in functional analysis as a mathematical discipline and the ever-increasing role played by its techniques in applications. The theory of topological vector spaces is emphasized, along with the applications of functional analysis to applied analysis. Some topics of functional analysis connected with applications to mathematical economics and control theory are also discussed. Comprised of 18 chapters, this book begins with an introduction to the elements of the theory of topological spaces, the theory of metric spaces, and the theory of abstract measure space

Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

Energy Technology Data Exchange (ETDEWEB)

Lee C. Cadwallader

2010-06-01

This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance.

Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

Energy Technology Data Exchange (ETDEWEB)

Lee C. Cadwallader

2007-08-01

This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with “generic” component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance.

Preliminary Failure Modes and Effects Analysis of the US DCLL Test Blanket Module

International Nuclear Information System (INIS)

Lee C. Cadwallader

2007-01-01

This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a small tritium-breeding test blanket module design for the International Thermonuclear Experimental Reactor. The FMEA was quantified with 'generic' component failure rate data, and the failure events are binned into postulated initiating event families and frequency categories for safety assessment. An appendix to this report contains repair time data to support an occupational radiation exposure assessment for test blanket module maintenance

Effect of mibefradil on left ventricular diastolic function in patients with congestive heart failure

NARCIS (Netherlands)

Muntinga, HJ; vanderVring, JAFM; Niemeyer, MG; vandenBerg, F; Knol, HR; Bernink, PJLM; vanderWall, EE; Blanksma, PK; Lie, KI

Calcium antagonists have antihypertensive and antianginal properties. In heart failure, however, their use can be hazardous, as systolic function can deteriorate. This may nor be true of the new calcium antagonist mibefradil, which has a new chemical structure. Calcium antagonists may also be

Vascular endothelial cell function and cardiovascular risk factors in patients with chronic renal failure

DEFF Research Database (Denmark)

Haaber, A B; Eidemak, I; Jensen, T

1995-01-01

Cardiovascular risk factors and markers of endothelial cell function were studied in nondiabetic patients with mild to moderate chronic renal failure. The transcapillary escape rate of albumin and the plasma concentrations of von Willebrand factor, fibrinogen, and plasma lipids were measured in 29...

Preliminary Analysis of the Common Cause Failure Events for Domestic Nuclear Power Plants

International Nuclear Information System (INIS)

Kang, Daeil; Han, Sanghoon

2007-01-01

It is known that the common cause failure (CCF) events have a great effect on the safety and probabilistic safety assessment (PSA) results of nuclear power plants (NPPs). However, the domestic studies have been mainly focused on the analysis method and modeling of CCF events. Thus, the analysis of the CCF events for domestic NPPs were performed to establish a domestic database for the CCF events and to deliver them to the operation office of the international common cause failure data exchange (ICDE) project. This paper presents the analysis results of the CCF events for domestic nuclear power plants

Endothelial function is unaffected by changing between carvedilol and metoprolol in patients with heart failure-a randomized study

DEFF Research Database (Denmark)

Falskov, Britt; Hermann, Thomas Steffen; Raunsø, Jakob

2011-01-01

Carvedilol has been shown to be superior to metoprolol tartrate to improve clinical outcomes in patients with heart failure (HF), yet the mechanisms responsible for these differences remain unclear. We examined if there were differences in endothelial function, insulin stimulated endothelial func...... function, 24 hour ambulatory blood pressure and heart rate during treatment with carvedilol, metoprolol tartrate and metoprolol succinate in patients with HF.......Carvedilol has been shown to be superior to metoprolol tartrate to improve clinical outcomes in patients with heart failure (HF), yet the mechanisms responsible for these differences remain unclear. We examined if there were differences in endothelial function, insulin stimulated endothelial...

A model-based prognostic approach to predict interconnect failure using impedance analysis

Energy Technology Data Exchange (ETDEWEB)

Kwon, Dae Il; Yoon, Jeong Ah [Dept. of System Design and Control Engineering. Ulsan National Institute of Science and Technology, Ulsan (Korea, Republic of)

2016-10-15

The reliability of electronic assemblies is largely affected by the health of interconnects, such as solder joints, which provide mechanical, electrical and thermal connections between circuit components. During field lifecycle conditions, interconnects are often subjected to a DC open circuit, one of the most common interconnect failure modes, due to cracking. An interconnect damaged by cracking is sometimes extremely hard to detect when it is a part of a daisy-chain structure, neighboring with other healthy interconnects that have not yet cracked. This cracked interconnect may seem to provide a good electrical contact due to the compressive load applied by the neighboring healthy interconnects, but it can cause the occasional loss of electrical continuity under operational and environmental loading conditions in field applications. Thus, cracked interconnects can lead to the intermittent failure of electronic assemblies and eventually to permanent failure of the product or the system. This paper introduces a model-based prognostic approach to quantitatively detect and predict interconnect failure using impedance analysis and particle filtering. Impedance analysis was previously reported as a sensitive means of detecting incipient changes at the surface of interconnects, such as cracking, based on the continuous monitoring of RF impedance. To predict the time to failure, particle filtering was used as a prognostic approach using the Paris model to address the fatigue crack growth. To validate this approach, mechanical fatigue tests were conducted with continuous monitoring of RF impedance while degrading the solder joints under test due to fatigue cracking. The test results showed the RF impedance consistently increased as the solder joints were degraded due to the growth of cracks, and particle filtering predicted the time to failure of the interconnects similarly to their actual timesto- failure based on the early sensitivity of RF impedance.

Studies on failure kind analysis of the radiologic medical equipment in general hospital

International Nuclear Information System (INIS)

Lee, Woo Cheul; Kim, Jeong Lae

1999-01-01

This paper included a data analysis of the unit of medical devices using maintenance recording card that had medical devices of unit failure mode, hospital of failure mode and MTBF. The results of the analysis were as follows : 1. Medical devices of unit failure mode was the highest in QC/PM such A hospital as 33.9%, B hospital 30.9%, C hospital 30.3%, second degree was the Electrical and Electronic failure such A hospital as 23.5%, B hospital 25.3%, C hospital 28%, third degree was mechanical failure such A hospital as 19.6%, B hospital 22.5%, C hospital 25.4%. 2. Hospital of failure mode was the highest in Mobile X-ray device(A hospital 62.5%, B hospital 69.5%, C hospital 37.4%), and was the lowest in Sono devices(A hospital 16.76%, B hospital 8.4%, C hospital 7%). 3. Mean time between failures(MTBT) was the highest in SONO devices and was the lowest in Mobile X-ray devices which have 200 - 400 failure hours. 4. Average failure ratio was the highest in Mobile X-ray devices(A hospital 31.3%, B hospital 34.8%, C hospital 18.7%), and was the lowest in Sono(Ultrasound) devices (A hospital 8.4%, B hospital 4.2%, C hospital 3.5%). 5. Failure ratio results of medical devices according to QC/PM part of unit failure mode were as follows ; A hospital was the highest part of QC/PM (50%) in Mamo X-ray device and was the lowest part of QC/PM(26.4%) in Gastro X-ray. B hospital was the highest part of QC/PM(56%) in Mobile X-ray device, and the lowest part of QC/PM(12%) in Gastro X-ray. C hospital was the highest part of QC/PM(60%) in R/F X-ray device, and the lowest a part of QC/PM(21%) in Universal X-ray. It was found that the units responsible for most failure decreased by systematic management. We made the preventive maintenance schedule focusing on adjustment of operating and dust removal

Regulatory analysis for the resolution of Generic Issue 130: Essential service water system failures at multi-unit sites

International Nuclear Information System (INIS)

Leung, V.; Basdekas, D.; Mazetis, G.

1991-06-01

The essential service water system (ESWS) is required to provide cooling in nuclear power plants during normal operation and accident conditions. The ESWS typically supports component cooling water heat exchangers, containment spray heat exchangers, high-pressure injection pump oil coolers, emergency diesel generators, and auxiliary building ventilation coolers. Failure of the ESWS function could lead to severe consequences. This report presents the regulatory analysis for GI-130, ''Essential Service Water System Failures at Multi-Unit Sites.'' The risk reduction estimates, cost/benefit analyses, and other insights gained during this effort have shown that implementation of the recommendations will significantly reduce risk and that these improvements are warranted in accordance with the backfit rule, 10 CFR 50.109(a)(3). 19 refs., 16 tabs

Advanced composites structural concepts and materials technologies for primary aircraft structures: Structural response and failure analysis

Science.gov (United States)

Dorris, William J.; Hairr, John W.; Huang, Jui-Tien; Ingram, J. Edward; Shah, Bharat M.

1992-01-01

Non-linear analysis methods were adapted and incorporated in a finite element based DIAL code. These methods are necessary to evaluate the global response of a stiffened structure under combined in-plane and out-of-plane loading. These methods include the Arc Length method and target point analysis procedure. A new interface material model was implemented that can model elastic-plastic behavior of the bond adhesive. Direct application of this method is in skin/stiffener interface failure assessment. Addition of the AML (angle minus longitudinal or load) failure procedure and Hasin's failure criteria provides added capability in the failure predictions. Interactive Stiffened Panel Analysis modules were developed as interactive pre-and post-processors. Each module provides the means of performing self-initiated finite elements based analysis of primary structures such as a flat or curved stiffened panel; a corrugated flat sandwich panel; and a curved geodesic fuselage panel. This module brings finite element analysis into the design of composite structures without the requirement for the user to know much about the techniques and procedures needed to actually perform a finite element analysis from scratch. An interactive finite element code was developed to predict bolted joint strength considering material and geometrical non-linearity. The developed method conducts an ultimate strength failure analysis using a set of material degradation models.

Laboratory and 3-D distinct element analysis of the failure mechanism of a slope under external surcharge

Science.gov (United States)

Li, N.; Cheng, Y. M.

2015-01-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the post-failure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.

Systems analysis determining critical items, critical assembly processes, primary failure modes and corrective actions on ASST magnets

International Nuclear Information System (INIS)

Arden, C.S.

1993-04-01

During the assembly process through the completion of the Accelerator Surface String Test (ASST) phase one test, Magnet Systems Division Reliability Engineering has tracked all the known discrepancies utilizing the Failure Reporting, Analysis and Corrective Action System (FRACAS) and data base. This paper discusses the critical items, critical assembly processes, primary failure modes and corrective actions (lessons learned) based on actual data for the ASST magnets. The ASST magnets include seven Brookhaven Lab Dipoles (DCA-207 through 213), fourteen Fermi Lab Dipoles (DCA-310 through 323) and five Lawrence Berkeley Lab Quadrupoles (QCC-402 through 406). Between all the ASST magnets built there were one hundred eighty six (186) class one discrepancies reported out of approximately eleven hundred total discrepancy reports. The class one or critical discrepancies are defined as form, fit, function, safety or reliability problem. Each and every ASST magnet is considered a success, as they all achieved the quench performance requirements and were capable of being incorporated into the string test. This paper also discuss some specific magnet discrepancies, including failure cause(s), corrective action and possible open issues

Systems analysis determining critical items, critical assembly processes, primary failure modes and corrective actions on ASST magnets

International Nuclear Information System (INIS)

Arden, C.S.

1994-01-01

During the assembly process through the completion of the Accelerator Surface String Test (ASST) phase one test, Magnet Systems Division Reliability Engineering has tracked all the known discrepancies utilizing the Failure Reporting, Analysis and Corrective Action System (FRACAS) and data base. This paper discusses the critical items, critical assembly processes, primary failure modes and corrective actions (lessons learned) based on actual data for the ASST magnets. The ASST magnets include seven Brookhaven Lab Dipoles (DCA-207 through 213), fourteen Fermi Lab Dipoles (DCA-310 through 323) and five Lawrence Berkeley Lab Quadrupoles (QCC-402 through 406). Between all the ASST magnets built there were one hundred eighty six (186) class one discrepancies reported out of approximately eleven hundred total discrepancy reports. The class one or critical discrepancies are defined as form, fit, function, safety or reliability problem. Each and every ASST magnet is considered a success, as they all achieved the quench performance requirements and were capable of being incorporated into the string test. This paper will also discuss some specific magnet discrepancies, including failure cause(s), corrective action and possible open issues