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Sample records for failure analysis summary

  1. Summary of failure analysis activities at Brookhaven National Laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Cowgill, M.G.; Czajkowski, C.J.; Franz, E.M.

    1996-10-01

    Brookhaven National Laboratory has for many years conducted examinations related to the failures of nuclear materials and components. These examinations included the confirmation of root cause analyses, the determination of the causes of failure, identification of the species that accelerate corrosion, and comparison of the results of nondestructive examinations with those obtained by destructive examination. The results of those examinations, which had previously appeared in various formats (formal and informal reports, journal articles, etc.), have been collected together and summarized in the present report. The report is divided into sections according to the general subject matter (for example, corrosion, fatigue, etc.). Each section presents summaries of the information contained in specific reports and publications, all of which are fully identified as to title, authors, report number or journal reference, date of publication, and FIN number under which the work was performed.

  2. Integrated Logistics Support Analysis of the International Space Station Alpha, Background and Summary of Mathematical Modeling and Failure Density Distributions Pertaining to Maintenance Time Dependent Parameters

    Science.gov (United States)

    Sepehry-Fard, F.; Coulthard, Maurice H.

    1995-01-01

    The process of predicting the values of maintenance time dependent variable parameters such as mean time between failures (MTBF) over time must be one that will not in turn introduce uncontrolled deviation in the results of the ILS analysis such as life cycle costs, spares calculation, etc. A minor deviation in the values of the maintenance time dependent variable parameters such as MTBF over time will have a significant impact on the logistics resources demands, International Space Station availability and maintenance support costs. There are two types of parameters in the logistics and maintenance world: a. Fixed; b. Variable Fixed parameters, such as cost per man hour, are relatively easy to predict and forecast. These parameters normally follow a linear path and they do not change randomly. However, the variable parameters subject to the study in this report such as MTBF do not follow a linear path and they normally fall within the distribution curves which are discussed in this publication. The very challenging task then becomes the utilization of statistical techniques to accurately forecast the future non-linear time dependent variable arisings and events with a high confidence level. This, in turn, shall translate in tremendous cost savings and improved availability all around.

  3. Integrated Logistics Support Analysis of the International Space Station Alpha, Background and Summary of Mathematical Modeling and Failure Density Distributions Pertaining to Maintenance Time Dependent Parameters

    Science.gov (United States)

    Sepehry-Fard, F.; Coulthard, Maurice H.

    1995-01-01

    The process of predicting the values of maintenance time dependent variable parameters such as mean time between failures (MTBF) over time must be one that will not in turn introduce uncontrolled deviation in the results of the ILS analysis such as life cycle costs, spares calculation, etc. A minor deviation in the values of the maintenance time dependent variable parameters such as MTBF over time will have a significant impact on the logistics resources demands, International Space Station availability and maintenance support costs. There are two types of parameters in the logistics and maintenance world: a. Fixed; b. Variable Fixed parameters, such as cost per man hour, are relatively easy to predict and forecast. These parameters normally follow a linear path and they do not change randomly. However, the variable parameters subject to the study in this report such as MTBF do not follow a linear path and they normally fall within the distribution curves which are discussed in this publication. The very challenging task then becomes the utilization of statistical techniques to accurately forecast the future non-linear time dependent variable arisings and events with a high confidence level. This, in turn, shall translate in tremendous cost savings and improved availability all around.

  4. Failure Analysis Handbook

    Science.gov (United States)

    1989-08-18

    47) described a method they called the "failure-experience matrix." This matrix was a three-dimensional array of cells , with failure modes along one...Russo, DFat ý , compiled by McDonnell-Dcuglas Astrovautics Cmpany, Huntington Beach, California, published by Metals and Ceramics Information Center...matrix." This matrix was a three dimensional array of cells , with failure modes along one axis, ryont "mechardcal function along a second axis and

  5. BIOASSAY VESSEL FAILURE ANALYSIS

    Energy Technology Data Exchange (ETDEWEB)

    Vormelker, P

    2008-09-22

    Two high-pressure bioassay vessels failed at the Savannah River Site during a microwave heating process for biosample testing. Improper installation of the thermal shield in the first failure caused the vessel to burst during microwave heating. The second vessel failure is attributed to overpressurization during a test run. Vessel failure appeared to initiate in the mold parting line, the thinnest cross-section of the octagonal vessel. No material flaws were found in the vessel that would impair its structural performance. Content weight should be minimized to reduce operating temperature and pressure. Outer vessel life is dependent on actual temperature exposure. Since thermal aging of the vessels can be detrimental to their performance, it was recommended that the vessels be used for a limited number of cycles to be determined by additional testing.

  6. Time between failures model and failure analysis of CNC system

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hai-bo; JIA Ya-zhou; ZHOU Guang-wen

    2007-01-01

    To provide basis for the reliability improvement design of CNC system, the failure data of a type of CNC system in one year are collected under field conditions in workshops. The distribution model parameters of time between failures are estimated by least square method and hypothesis testing is done by d-test method. It is proved that the time between failures of the CNC system follows Weibull distribution and the system has entered into the wear-out failure period. The failure positions and failure causes are analyzed further to indicate the weak subsystems of the CNC system. It can be found that servo unit, electrical system, detecting unit and power supply are principal failure positions and the main failure cause is breakage of components. The corresponding improvement measures are put forward. The paper provides a reference to reliability design and analysis of CNC system for the manufacturer and has great guidance to using and maintaining CNC system for the user.

  7. Failure rate analysis using GLIMMIX

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-12-01

    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.

  8. Administrative Utility Analysis: Study Summary.

    Science.gov (United States)

    Peat, Marwick, Mitchell and Co., San Juan, Puerto Rico.

    This document summarizes the recommendations made as a result of a study on administrative utility analysis and vocational education programs for Puerto Rico. The major recommendation was that the Area of Vocational and Technical Education (AVTE) in the Puerto Rico Department of Education be restructured at the central organizational level, for…

  9. Mist lift analysis summary report

    Energy Technology Data Exchange (ETDEWEB)

    Davenport, R.L.

    1980-09-01

    The mist flow open-cycle OTEC concept proposed by S.L. Ridgway has much promise, but the fluid mechanics of the mist flow are not well understood. The creation of the mist and the possibility of droplet growth leading to rainout (when the vapor can no longer support the mist) are particularly troublesome. This report summarizes preliminary results of a numerical analysis initiated at SERI in FY79 to study the mist-lift process. The analysis emphasizes the mass transfer and fluid mechanics of the steady-state mist flow and is based on one-dimensional models of the mist flow developed for SERI by Graham Wallis. One of Wallis's models describes a mist composed of a single size of drops and another considers several drop sizes. The latter model, further developed at SERI, considers a changing spectrum of discrete drop sizes and incorporates the mathematics describing collisions and growth of the droplets by coalescence. The analysis results show that under conditions leading to maximum lift in the single-drop-size model, the multigroup model predicts significantly reduced lift because of the growth of droplets by coalescence. The predicted lift height is sensitive to variations in the mass flow rate and inlet pressure. Inclusion of a coasting section, in which the drops would rise ballistically without change in temperature, may lead to increased lift within the existing range of operation.

  10. Charles M. Russell National Wildlife Range Wilderness proposal public hearing summary analysis and wilderness study summary

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This document contains both a public hearing summary analysis and a wilderness study summary for the Charles M. Russell National Wildlife Range. The public hearing...

  11. 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

  12. Wind Turbine Failures - Tackling current Problems in Failure Data Analysis

    Science.gov (United States)

    Reder, M. D.; Gonzalez, E.; Melero, J. J.

    2016-09-01

    The wind industry has been growing significantly over the past decades, resulting in a remarkable increase in installed wind power capacity. Turbine technologies are rapidly evolving in terms of complexity and size, and there is an urgent need for cost effective operation and maintenance (O&M) strategies. Especially unplanned downtime represents one of the main cost drivers of a modern wind farm. Here, reliability and failure prediction models can enable operators to apply preventive O&M strategies rather than corrective actions. In order to develop these models, the failure rates and downtimes of wind turbine (WT) components have to be understood profoundly. This paper is focused on tackling three of the main issues related to WT failure analyses. These are, the non-uniform data treatment, the scarcity of available failure analyses, and the lack of investigation on alternative data sources. For this, a modernised form of an existing WT taxonomy is introduced. Additionally, an extensive analysis of historical failure and downtime data of more than 4300 turbines is presented. Finally, the possibilities to encounter the lack of available failure data by complementing historical databases with Supervisory Control and Data Acquisition (SCADA) alarms are evaluated.

  13. Renal sympathetic denervation for treatment of patients with heart failure: summary of the available evidence.

    Science.gov (United States)

    Nammas, Wail; Koistinen, Juhani; Paana, Tuomas; Karjalainen, Pasi P

    2017-02-10

    Heart failure syndrome results from compensatory mechanisms that operate to restore - back to normal - the systemic perfusion pressure. Sympathetic overactivity plays a pivotal role in heart failure; norepinephrine contributes to maintenance of the systemic blood pressure and increasing preload. Cardiac norepinephrine spillover increases in patients with heart failure; norepinephrine exerts direct toxicity on cardiac myocytes resulting in a decrease of synthetic activity and/or viability. Importantly, cardiac norepinephrine spillover is a powerful predictor of mortality in patients with moderate to severe HF. This provided the rationale for trials that demonstrated survival benefit associated with the use of beta adrenergic blockers in heart failure with reduced ejection fraction. Nevertheless, the MOXCON trial demonstrated that rapid uptitration of moxonidine (inhibitor of central sympathetic outflow) in patients with heart failure was associated with excess mortality and morbidity, despite reduction of plasma norepinephrine. Interestingly, renal norepinephrine spillover was the only independent predictor of adverse outcome in patients with heart failure, in multivariable analysis. Recently, renal sympathetic denervation has emerged as a novel approach for control of blood pressure in patients with treatment-resistant hypertension. This article summarizes the available evidence for the effect of renal sympathetic denervation in the setting of heart failure. Key messages Experimental studies supported a beneficial effect of renal sympathetic denervation in heart failure with reduced ejection fraction. Clinical studies demonstrated improvement of symptoms, and left ventricular function. In heart failure and preserved ejection fraction, renal sympathetic denervation is associated with improvement of surrogate endpoints.

  14. Uranium enrichment management review: summary of analysis

    Energy Technology Data Exchange (ETDEWEB)

    1981-01-01

    In May 1980, the Assistant Secretary for Resource Applications within the Department of Energy requested that a group of experienced business executives be assembled to review the operation, financing, and management of the uranium enrichment enterprise as a basis for advising the Secretary of Energy. After extensive investigation, analysis, and discussion, the review group presented its findings and recommendations in a report on December 2, 1980. The following pages contain background material on which that final report was based. This report is arranged in chapters that parallel those of the uranium enrichment management review final report - chapters that contain summaries of the review group's discussion and analyses in six areas: management of operations and construction; long-range planning; marketing of enrichment services; financial management; research and development; and general management. Further information, in-depth analysis, and discussion of suggested alternative management practices are provided in five appendices.

  15. 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.

  16. 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.

  17. Failure modes and effects analysis automation

    Science.gov (United States)

    Kamhieh, Cynthia H.; Cutts, Dannie E.; Purves, R. Byron

    1988-01-01

    A failure modes and effects analysis (FMEA) assistant was implemented as a knowledge based system and will be used during design of the Space Station to aid engineers in performing the complex task of tracking failures throughout the entire design effort. The three major directions in which automation was pursued were the clerical components of the FMEA process, the knowledge acquisition aspects of FMEA, and the failure propagation/analysis portions of the FMEA task. The system is accessible to design, safety, and reliability engineers at single user workstations and, although not designed to replace conventional FMEA, it is expected to decrease by many man years the time required to perform the analysis.

  18. SIMS analysis: Development and evaluation program summary

    Energy Technology Data Exchange (ETDEWEB)

    Groenewold, G.S.; Appelhans, A.D.; Ingram, J.C.; Delmore, J.E.; Dahl, D.A.

    1996-11-01

    This report provides an overview of the ``SIMS Analysis: Development and Evaluation Program``, which was executed at the Idaho National Engineering Laboratory from mid-FY-92 to the end of FY-96. It should be noted that prior to FY-1994 the name of the program was ``In-Situ SIMS Analysis``. This report will not go into exhaustive detail regarding program accomplishments, because this information is contained in annual reports which are referenced herein. In summary, the program resulted in the design and construction of an ion trap secondary ion mass spectrometer (IT-SIMS), which is capable of the rapid analysis of environmental samples for adsorbed surface contaminants. This instrument achieves efficient secondary ion desorption by use of a molecular, massive ReO{sub 4}{sup {minus}} primary ion particle. The instrument manages surface charge buildup using a self-discharging principle, which is compatible with the pulsed nature of the ion trap. The instrument can achieve high selectivity and sensitivity using its selective ion storage and MS/MS capability. The instrument was used for detection of tri-n-butyl phosphate, salt cake (tank cake) characterization, and toxic metal speciation studies (specifically mercury). Technology transfer was also an important component of this program. The approach that was taken toward technology transfer was that of component transfer. This resulted in transfer of data acquisition and instrument control software in FY-94, and ongoing efforts to transfer primary ion gun and detector technology to other manufacturers.

  19. Failure analysis of jet engine turbine blade

    OpenAIRE

    MILAN T. JOVANOVIĆ; Vesna Maksimović; Ivana Cvijović-Alagić

    2016-01-01

    Jet engine turbine blade cast by investment precision casting of Ni-base superalloy, which failed during exploatation, was the subject of investigation. Failure analysis was executed applying optical microscopy (OM), transmission electron microscopy (TEM) using replica technique, scaning electron microscopy (SEM) and stress rupture life tests. On the ground of obtained results it was concluded that the failure occurred as a result of structural changes caused by turbine blade overheating abov...

  20. Failure analysis of jet engine turbine blade

    Directory of Open Access Journals (Sweden)

    Milan T. Jovanović

    2016-03-01

    Full Text Available Jet engine turbine blade cast by investment precision casting of Ni-base superalloy, which failed during exploatation, was the subject of investigation. Failure analysis was executed applying optical microscopy (OM, transmission electron microscopy (TEM using replica technique, scaning electron microscopy (SEM and stress rupture life tests. On the ground of obtained results it was concluded that the failure occurred as a result of structural changes caused by turbine blade overheating above the exploitation temperature.

  1. Summary

    Science.gov (United States)

    Habing, H.

    2004-07-01

    Summaries of conferences consist of subjective views of the reviewer, on what he remarked, of what he thought was important. And yet some of these remarks may be of interest to all participants. The event called "inspiration" may happen when scientist A gets an idea because of a brilliant or of stupid remark she heard when scientist B gave a summary. So, what is a good review? A review that broadens the perspective of at least some people in the audience. I hope that my attempt works. Let's see.

  2. 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.

  3. FAILURE ANALYSIS: WASTEWATER DRUM BULGING

    Energy Technology Data Exchange (ETDEWEB)

    Vormelker, P

    2008-09-15

    A 55 gallon wastewater drum lid was found to be bulged during storage in a remote area. Drum samples were obtained for analysis. The interior surface of these samples revealed blistering and holes in the epoxy phenolic drum liner and corrosion of the carbon steel drum. It is suspected that osmotic pressure drove permeation of the water through the epoxy phenolic coating which was weakened from exposure to low pH water. The coating failed at locations throughout the drum interior. Subsequent corrosion of the carbon steel released hydrogen which pressurized the drum causing deformation of the drum lid. Additional samples from other wastewater drums on the same pallet were also evaluated and limited corrosion was visible on the interior surfaces. It is suspected that, with time, the corrosion would have advanced to cause pressurization of these sealed drums.

  4. Failure analysis of a polymer centrifugal impeller

    Directory of Open Access Journals (Sweden)

    Nikhil K. Kar

    2015-10-01

    Full Text Available A failure analysis investigation was performed on a fractured polymer impeller used in a respiratory blower. Light microscopy, scanning electron microscopy and finite element analysis techniques were utilized to characterize the mode(s of failure and fracture surfaces. A radial split down the impeller center was observed with symmetric fracture faces about the impeller bore. Fractographic analysis revealed brittle fracture features including Wallner lines, mirror, mist and hackle features stemming from the impeller bore, emanating radially outward. Crazed fibrils and faint fatigue striations suggest that intermittent load cycling led to initiation, and rapid propagation of multiple crack fronts originating along the impeller lip. Finite element analysis revealed a flexural condition induces localized stresses along the impeller lip. Significant wear features were also observed within the impeller bore, which may have contributed to premature failure of the impeller. The brittle fracture morphology and defects within the impeller bore suggest that premature failure occurred because of multiple interacting factors including: intermittently high centrifugal velocities, imbalance bore and shaft conditions, defects within the bore caused by machining, and stress concentrations along the circumference of the impeller lip.

  5. 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.

  6. Summary of coyote scat analysis for bird consumption : summer 2011

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Summary report for the summer project of coyote scat analysis on Fish Springs National Wildlife Refuge. The objective of this study was to determine what coyotes...

  7. FUZZY METHOD FOR FAILURE CRITICALITY ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The greatest benefit is realized from failure mode, effect and criticality analysis (FMECA) when it is done early in the design phase and tracks product changes as they evolve; design changes can then be made more economically than if the problems are discovered after the design has been completed. However, when the discovered design flaws must be prioritized for corrective actions, precise information on their probability of occurrence, the effect of the failure, and their detectability often are not availabe. To solve this problem, this paper described a new method, based on fuzzy sets, for prioritizing failures for corrective actions in a FMCEA. Its successful application to the container crane shows that the proposed method is both reasonable and practical.

  8. 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.

  9. 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.

  10. 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...

  11. 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...

  12. Failure Mode and Effect Analysis of Active Magnetic Bearings

    Directory of Open Access Journals (Sweden)

    K.P. Lijesh

    2016-03-01

    Full Text Available In the present research work Failure Mode and Effect Analysis (FMEA of an Active Magnetic Bearing (AMB has been presented. Various possible failures modes of AMBs and the corresponding effects of those failures on performance of AMBs have been identified. The identified failure modes of AMBs will facilitate designer to incorporate necessary design features that would prevent the occurrence of the failure. The severity, occurrence and detection of the failures modes are determined based on a rating scale of 1 to 5 to quantify the Risk Priority Number (RPN of the failure modes. The methods to eliminate or reduce the high-risk-failure modes are proposed.

  13. Failure-Modes-And-Effects Analysis Of Software Logic

    Science.gov (United States)

    Garcia, Danny; Hartline, Thomas; Minor, Terry; Statum, David; Vice, David

    1996-01-01

    Rigorous analysis applied early in design effort. Method of identifying potential inadequacies and modes and effects of failures caused by inadequacies (failure-modes-and-effects analysis or "FMEA" for short) devised for application to software logic.

  14. Timing analysis of PWR fuel pin failures

    Energy Technology Data Exchange (ETDEWEB)

    Jones, K.R.; Wade, N.L.; Katsma, K.R.; Siefken, L.J. (EG and G Idaho, Inc., Idaho Falls, ID (United States)); Straka, M. (Halliburton NUS, Idaho Falls, ID (United States))

    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 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 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 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.

  15. BUSINESS FAILURE PREDICTION FOR ROMANIAN SMES USING MULTIVARIATE DISCRIMINANT ANALYSIS

    OpenAIRE

    2012-01-01

    Business failure prediction is one of special importance for small and medium sized enterprises (SMEs) due to their increased vulnerability. Consequently, the purpose of this paper is to investigate the utility of financial ratios and other non-financial variables to predict business failure using a sample of Romanian SMEs and applying multiple discriminant analysis. The process that leads to failure is analyzed on a three year time horizon prior to failure and the results showed that failure...

  16. Staffing for Cyberspace Operations: Summary of Analysis

    Science.gov (United States)

    2016-08-01

    information , including suggestions for reducing the burden, to Department of Defense, Washington Headquarters Services , Directorate for Information Operations...Analysis and Integration , Office of the Secretary of Defense Cost Assessment and Program Evaluation; and the Director, Acquisition Resources and...findings and recommendations of a full-length report containing classified information .1 It is meant to make the key elements of the analysis accessible

  17. 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...

  18. System failure analysis based on DEMATEL-ISM and FMECA

    Institute of Scientific and Technical Information of China (English)

    申桂香; 孙曙光; 张英芝; 王志琼; 陈炳锟; 马闯

    2014-01-01

    A new method of system failure analysis was proposed. First, considering the relationships between the failure subsystems, the decision making trial and evaluation laboratory (DEMATEL) method was used to calculate the degree of correlation between the failure subsystems, analyze the combined effect of related failures, and obtain the degree of correlation by using the directed graph and matrix operations. Then, the interpretative structural modeling (ISM) method was combined to intuitively show the logical relationship of many failure subsystems and their influences on each other by using multilevel hierarchical structure model and obtaining the critical subsystems. Finally, failure mode effects and criticality analysis (FMECA) was used to perform a qualitative hazard analysis of critical subsystems, determine the critical failure mode, and clarify the direction of reliability improvement. Through an example, the result demonstrates that the proposed method can be efficiently applied to system failure analysis problems.

  19. Staffing for Cyberspace Operations: Summary of Analysis

    Science.gov (United States)

    2016-08-01

    Service’s current mix with the IDA alternative). The costing was performed in accordance with guidance and cost elements laid out in DoDI 7041.04.5 The...capable of carrying out cyberspace operations is currently a major force planning effort in the Department of Defense (DoD). Determining the...Analysis and Integration, Office of the Secretary of Defense Cost Assessment and Program Evaluation; and the Director, Acquisition Resources and

  20. Summary of CPAS Gen II Parachute Analysis

    Science.gov (United States)

    Morris, Aaron L.; Bledsoe, Kristin J.; Fraire, Usbaldo, Jr.; Moore, James W.; Olson, Leah M.; Ray, Eric

    2011-01-01

    The Orion spacecraft is currently under development by NASA and Lockheed Martin. Like Apollo, Orion will use a series of parachutes to slow its descent and splashdown safely. The Orion parachute system, known as the CEV Parachute Assembly System (CPAS), is being designed by NASA, the Engineering and Science Contract Group (ESCG), and Airborne Systems. The first generation (Gen I) of CPAS testing consisted of thirteen tests and was executed in the 2007-2008 timeframe. The Gen I tests provided an initial understanding of the CPAS parachutes. Knowledge gained from Gen I testing was used to plan the second generation of testing (Gen II). Gen II consisted of six tests: three singleparachute tests, designated as Main Development Tests, and three Cluster Development Tests. Gen II required a more thorough investigation into parachute performance than Gen I. Higher fidelity instrumentation, enhanced analysis methods and tools, and advanced test techniques were developed. The results of the Gen II test series are being incorporated into the CPAS design. Further testing and refinement of the design and model of parachute performance will occur during the upcoming third generation of testing (Gen III). This paper will provide an overview of the developments in CPAS analysis following the end of Gen I, including descriptions of new tools and techniques as well as overviews of the Gen II tests.

  1. Summary of CPAS EDU Testing Analysis Results

    Science.gov (United States)

    Romero, Leah M.; Bledsoe, Kristin J.; Davidson, John.; Engert, Meagan E.; Fraire, Usbaldo, Jr.; Galaviz, Fernando S.; Galvin, Patrick J.; Ray, Eric S.; Varela, Jose

    2015-01-01

    The Orion program's Capsule Parachute Assembly System (CPAS) project is currently conducting its third generation of testing, the Engineering Development Unit (EDU) series. This series utilizes two test articles, a dart-shaped Parachute Compartment Drop Test Vehicle (PCDTV) and capsule-shaped Parachute Test Vehicle (PTV), both of which include a full size, flight-like parachute system and require a pallet delivery system for aircraft extraction. To date, 15 tests have been completed, including six with PCDTVs and nine with PTVs. Two of the PTV tests included the Forward Bay Cover (FBC) provided by Lockheed Martin. Advancements in modeling techniques applicable to parachute fly-out, vehicle rate of descent, torque, and load train, also occurred during the EDU testing series. An upgrade from a composite to an independent parachute simulation allowed parachute modeling at a higher level of fidelity than during previous generations. The complexity of separating the test vehicles from their pallet delivery systems necessitated the use the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) simulator for modeling mated vehicle aircraft extraction and separation. This paper gives an overview of each EDU test and summarizes the development of CPAS analysis tools and techniques during EDU testing.

  2. Analysis on Failure Mode Severity of Machining Center Spindle System

    Institute of Scientific and Technical Information of China (English)

    Guixiang Shen; Shuguang Sun; Yingzhi Zhang; Xiaoyan Qi; Bingkun Chen

    2015-01-01

    According to the subjectivity and fuzziness of analysis on failure mode severity about spindle system of machining center, an analysis model of the failure mode severity of such a system is proposed based on the new fault severity index system, improved analytic hierarchy process ( IAHP ) and entropy⁃based fuzzy comprehensive evaluation. IAHP and entropy methods are adopted to determine the comprehensive failure severity index weight. The evaluation result is obtained after the factor set, comment set, weight set, and other parameters are determined, and then the level of risk degree and numerical value order of every spindle system failure mode is given. By taking an example, we verify that the proposed method can quantify the qualitative problem comprehensively, obtain more accurate analysis results, and provide the theoretical reference for mechanization and sequencing of failure mode effect analysis in reliability analysis. The calculation results can also serve as the basis of failure mode, effects, and criticality analysis in the subsequent step.

  3. Analysis of Waste Isolation Pilot Plant Samples: Integrated Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Britt, Phillip F [ORNL

    2015-03-01

    Analysis of Waste Isolation Pilot Plant Samples: Integrated Summary Report. Summaries of conclusions, analytical processes, and analytical results. Analysis of samples taken from the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico in support of the WIPP Technical Assessment Team (TAT) activities to determine to the extent feasible the mechanisms and chemical reactions that may have resulted in the breach of at least one waste drum and release of waste material in WIPP Panel 7 Room 7 on February 14, 2014. This report integrates and summarizes the results contained in three separate reports, described below, and draws conclusions based on those results. Chemical and Radiochemical Analyses of WIPP Samples R-15 C5 SWB and R16 C-4 Lip; PNNL-24003, Pacific Northwest National Laboratory, December 2014 Analysis of Waste Isolation Pilot Plant (WIPP) Underground and MgO Samples by the Savannah River National Laboratory (SRNL); SRNL-STI-2014-00617; Savannah River National Laboratory, December 2014 Report for WIPP UG Sample #3, R15C5 (9/3/14); LLNL-TR-667015; Lawrence Livermore National Laboratory, January 2015 This report is also contained in the Waste Isolation Pilot Plant Technical Assessment Team Report; SRNL-RP-2015-01198; Savannah River National Laboratory, March 17, 2015, as Appendix C: Analysis Integrated Summary Report.

  4. Failure Analysis of Aviation Torsional Springs

    Institute of Scientific and Technical Information of China (English)

    HOU Weiguo; ZHANG Weifang; LIU Xiao; WANG Zongren; DING Meili

    2011-01-01

    Cracks and fractures occur during the assembly process to a type of torsional springs used in the aviation mechanism.Besides visual examination,other experimental techniques used for the investigation are:1) fracture characteristics,damage morphology and ffactography by scanning electron microscopy(SEM),2) spectrum analysis of covering,3) metallographic observation of cracks and 4) hydrogen content testing.The results are obtained through the analysis of manufacture process and experimental data.Since no changes of microstructure are found,failures are irrelevant to the material.The cracks and fractures initiate on the inner surface,cracks initiate before the cadmium plating and after the winding.No obvious stress corrosion cracks are found near the crack source region.The opening direction of cracks is consistent with the residual tensile stress of the spring inner surface,and the springs are easy to contact hydrogen media between the spring winding and the cadmium plating.The cracks are caused by hydrogen-induced delayed cracking under the action of the residual tensile stress and hydrogen.

  5. Summary of Post Irradiation Examination Results of the AFIP-6 Failure

    Energy Technology Data Exchange (ETDEWEB)

    Adam Robinson; Daniel M. Wachs; Francine Rice; Danielle Perez

    2011-10-01

    The AFIP-6 test assembly was irradiated for one cycle in the Advanced Test Reactor at Idaho National Laboratory. The experiment was designed to test two monolithic fuel plates at power and burn-ups which bounded the operating conditions of both ATR and HFIR driver fuel. Both plates contain a solid U-Mo fuel foil with a zirconium diffusion barrier between 6061-aluminum cladding plates bonded by hot isostatic pressing. The experiment was designed with an orifice to restrict the coolant flow in order to obtain prototypic coolant temperature conditions. While these coolant temperatures were obtained, flow restriction resulted in low heat transfer coefficients and the failure of the fuel plates. The results from the post irradiation examinations and some observations of the failure mechanisms are outlined herein.

  6. 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.

  7. Microcircuit failure analysis using the SEM. [Scanning Electron Microscopes

    Science.gov (United States)

    Nicolas, D. P.

    1974-01-01

    The scanning electron microscope adds a new dimension to the knowledge that can be obtained from a failed microcircuit. When used with conventional techniques, SEM assists and clarifies the analysis, but it does not replace light microscopy. The most advantageous features for microcircuit analysis are long working distances and great depth of field. Manufacturer related failure modes of microcircuits are metallization defects, poor bonding, surface and particle contamination, and design and fabrication faults. User related failure modes are caused by abuse, such as overstress. The Physics of Failure Procedure followed by the Astrionics Laboratory in failure analysis is described, which is designed to obtain maximum information available from each step.

  8. Mod 1 wind turbine generator failure modes and effects analysis

    Science.gov (United States)

    1979-01-01

    A failure modes and effects analysis (FMEA) was directed primarily at identifying those critical failure modes that would be hazardous to life or would result in major damage to the system. Each subsystem was approached from the top down, and broken down to successive lower levels where it appeared that the criticality of the failure mode warranted more detail analysis. The results were reviewed by specialists from outside the Mod 1 program, and corrective action taken wherever recommended.

  9. Coal gasification systems engineering and analysis. Volume 1: Executive summary

    Science.gov (United States)

    1980-01-01

    Feasibility analyses and systems engineering studies for a 20,000 tons per day medium Btu (MBG) coal gasification plant to be built by TVA in Northern Alabama were conducted. Major objectives were as follows: (1) provide design and cost data to support the selection of a gasifier technology and other major plant design parameters, (2) provide design and cost data to support alternate product evaluation, (3) prepare a technology development plan to address areas of high technical risk, and (4) develop schedules, PERT charts, and a work breakdown structure to aid in preliminary project planning. Volume one contains a summary of gasification system characterizations. Five gasification technologies were selected for evaluation: Koppers-Totzek, Texaco, Lurgi Dry Ash, Slagging Lurgi, and Babcock and Wilcox. A summary of the trade studies and cost sensitivity analysis is included.

  10. Software Architecture Reliability Analysis using Failure Scenarios

    NARCIS (Netherlands)

    Tekinerdogan, B.; Sözer, Hasan; Aksit, Mehmet

    With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components

  11. Failure analysis of high performance ballistic fibers

    OpenAIRE

    Spatola, Jennifer S

    2015-01-01

    High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mo...

  12. Failure analysis of high performance ballistic fibers

    OpenAIRE

    Spatola, Jennifer S

    2015-01-01

    High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mo...

  13. Information architecture. Volume 2, Part 1: Baseline analysis summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    The Department of Energy (DOE) Information Architecture, Volume 2, Baseline Analysis, is a collaborative and logical next-step effort in the processes required to produce a Departmentwide information architecture. The baseline analysis serves a diverse audience of program management and technical personnel and provides an organized way to examine the Department`s existing or de facto information architecture. A companion document to Volume 1, The Foundations, it furnishes the rationale for establishing a Departmentwide information architecture. This volume, consisting of the Baseline Analysis Summary (part 1), Baseline Analysis (part 2), and Reference Data (part 3), is of interest to readers who wish to understand how the Department`s current information architecture technologies are employed. The analysis identifies how and where current technologies support business areas, programs, sites, and corporate systems.

  14. Information architecture. Volume 2, Part 1: Baseline analysis summary

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-12-01

    The Department of Energy (DOE) Information Architecture, Volume 2, Baseline Analysis, is a collaborative and logical next-step effort in the processes required to produce a Departmentwide information architecture. The baseline analysis serves a diverse audience of program management and technical personnel and provides an organized way to examine the Department`s existing or de facto information architecture. A companion document to Volume 1, The Foundations, it furnishes the rationale for establishing a Departmentwide information architecture. This volume, consisting of the Baseline Analysis Summary (part 1), Baseline Analysis (part 2), and Reference Data (part 3), is of interest to readers who wish to understand how the Department`s current information architecture technologies are employed. The analysis identifies how and where current technologies support business areas, programs, sites, and corporate systems.

  15. Micromechanics-Based Progressive Failure Analysis of Composite Laminates Using Different Constituent Failure Theories

    Science.gov (United States)

    Moncada, Albert M.; Chattopadhyay, Aditi; Bednarcyk, Brett A.; Arnold, Steven M.

    2008-01-01

    Predicting failure in a composite can be done with ply level mechanisms and/or micro level mechanisms. This paper uses the Generalized Method of Cells and High-Fidelity Generalized Method of Cells micromechanics theories, coupled with classical lamination theory, as implemented within NASA's Micromechanics Analysis Code with Generalized Method of Cells. The code is able to implement different failure theories on the level of both the fiber and the matrix constituents within a laminate. A comparison is made among maximum stress, maximum strain, Tsai-Hill, and Tsai-Wu failure theories. To verify the failure theories the Worldwide Failure Exercise (WWFE) experiments have been used. The WWFE is a comprehensive study that covers a wide range of polymer matrix composite laminates. The numerical results indicate good correlation with the experimental results for most of the composite layups, but also point to the need for more accurate resin damage progression models.

  16. Failure Analysis towards Reliable Performance of Aero-Engines

    Directory of Open Access Journals (Sweden)

    T. Jayakumar

    1999-10-01

    Full Text Available Aero-engines are critical components whose reliable performance decides the primary safety of anaircrafthelicopter. This is met by rigorous maintenance schedule with periodic inspection/nondestructive testingof various engine components. In spite of these measures, failure of areo-engines do occur rather frequentlyin comparison to failure of other components. Systematic failure analysis helps one to identify root causeof the failure, thus enabling remedial measures to prevent recurrence of such failures. Turbine blades madeof nickel or cobalt-based alloys are used in aero-engines. These blades are subjected to complex loadingconditions at elevated temperatures. The main causes of failure of blades are attributed to creep, thermalfatigue and hot corrosion. Premature failure of blades in the combustion zone was reported in one of theaero-engines. The engine had both the compressor and the free-turbine in a common shaft. Detailedfailure analysis revealed the presence of creep voids in the blades that failed. Failure of turbine bladeswas also detected in another aero-engine operating in a coastal environment. In this failure, the protectivecoating on the blades was cracked at many locations. Grain boundary spikes were observed on these locations.The primary cause of this failure was the hot corrosion followed by creep damage

  17. Analysis of Failure to Finish a Race in a Cohort of Thoroughbred Racehorses in New Zealand.

    Science.gov (United States)

    Tanner, Jasmine; Rogers, Chris; Bolwell, Charlotte; Cogger, Naomi; Gee, Erica; Mcllwraith, Wayne

    2016-05-25

    The objective was to describe the incidence of failure to finish a race in flat-racing Thoroughbreds in New Zealand as these are summary indicators of falls, injuries and poor performance. Retrospective data on six complete flat racing seasons (n = 188,615 race starts) of all Thoroughbred flat race starts from 1 August 2005 to 31 July 2011 were obtained. The incidence of failure to finish events and binomial exact 95% confidence intervals were calculated per 1000 horse starts. The association between horse-, rider- and race-level variables with the outcomes failure to finish, pulled-up/fell and lost rider were examined with a mixed effects Poisson regression model. A total of 544 horses failed to finish in 188,615 race starts with an overall incidence of 2.88 per 1000 horse starts (95% CI 2.64-3.12). The incidence of failure to finish horses across each race year showed little variability. In the univariable analysis race distance, larger field size, season, and ratings bands showed association with failing to finish a race. The overall failure to finish outcome was associated with season, race distance and ratings bands (horse experience and success ranking criteria). In the multivariable analysis, race distance and ratings bands were associated with horses that pulled-up/fell; season, apprentice allowances and ratings bands were associated with the outcome lost rider. The failure to finish rate was lower than international figures for race day catastrophic injury. Racing and environmental variables were associated with failure to finish a race highlighting the multifactorial nature of race-day events. Further investigation of risk factors for failure to finish is required to better understand the reasons for a low failure to finish rate in Thoroughbred flat races in New Zealand.

  18. Analysis of Failure to Finish a Race in a Cohort of Thoroughbred Racehorses in New Zealand

    Directory of Open Access Journals (Sweden)

    Jasmine Tanner

    2016-05-01

    Full Text Available The objective was to describe the incidence of failure to finish a race in flat-racing Thoroughbreds in New Zealand as these are summary indicators of falls, injuries and poor performance. Retrospective data on six complete flat racing seasons (n = 188,615 race starts of all Thoroughbred flat race starts from 1 August 2005 to 31 July 2011 were obtained. The incidence of failure to finish events and binomial exact 95% confidence intervals were calculated per 1000 horse starts. The association between horse-, rider- and race-level variables with the outcomes failure to finish, pulled-up/fell and lost rider were examined with a mixed effects Poisson regression model. A total of 544 horses failed to finish in 188,615 race starts with an overall incidence of 2.88 per 1000 horse starts (95% CI 2.64–3.12. The incidence of failure to finish horses across each race year showed little variability. In the univariable analysis race distance, larger field size, season, and ratings bands showed association with failing to finish a race. The overall failure to finish outcome was associated with season, race distance and ratings bands (horse experience and success ranking criteria. In the multivariable analysis, race distance and ratings bands were associated with horses that pulled-up/fell; season, apprentice allowances and ratings bands were associated with the outcome lost rider. The failure to finish rate was lower than international figures for race day catastrophic injury. Racing and environmental variables were associated with failure to finish a race highlighting the multifactorial nature of race-day events. Further investigation of risk factors for failure to finish is required to better understand the reasons for a low failure to finish rate in Thoroughbred flat races in New Zealand.

  19. 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

  20. Correlation failure analysis of an uncertain hysteretic vibration system

    Institute of Scientific and Technical Information of China (English)

    Zhang Xufang; Zhang Yimin; Hao Qiuju

    2008-01-01

    In this paper, a numerical method for correlation sensitivity analysis of a nonlinear random vibration system is presented. Based on the first passage failure model, the probability perturbation method is employed to determine the statistical characteristics of failure modes and the correlation between them. The sensitivity of correlation between failure modes with respect to random parameters characterizing the uncertainty of the hysteretic loop is discussed. In a numerical example, a two-DOF shear structure with uncertain hysteretic restoring force is considered. The statistical characteristics of response, failure modes and the sensitivity of random hysteretic loop parameters are provided, and also compared with a Monte Carlo simulation.

  1. A quantitative method for Failure Mode and Effects Analysis

    NARCIS (Netherlands)

    Braaksma, A.J.J.; 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

  2. Software architecture reliability analysis using failure scenarios

    NARCIS (Netherlands)

    Tekinerdogan, Bedir; Sozer, Hasan; Aksit, Mehmet

    2008-01-01

    With the increasing size and complexity of software in embedded systems, software has now become a primary threat for the reliability. Several mature conventional reliability engineering techniques exist in literature but traditionally these have primarily addressed failures in hardware components a

  3. Failure Analysis of Storage Data Magnetic Systems

    Directory of Open Access Journals (Sweden)

    Ortiz–Prado A.

    2010-10-01

    Full Text Available This paper shows the conclusions about the corrosion mechanics in storage data magnetic systems (hard disk. It was done from the inspection of 198 units that were in service in nine different climatic regions characteristic for Mexico. The results allow to define trends about the failure forms and the factors that affect them. In turn, this study has analyzed the causes that led to mechanical failure and those due to deterioration by atmospheric corrosion. On the basis of the results obtained from the field sampling, demonstrates that the hard disk failure is fundamentally by mechanical effects. The deterioration by environmental effects were found in read-write heads, integrated circuits, printed circuit boards and in some of the electronic components of the controller card of the device, but not in magnetic storage surfaces. There fore, you can discard corrosion on the surface of the disk as the main kind of failure due to environmental deterioration. To avoid any inconvenience in the magnetic data storage system it is necessary to ensure sealing of the system.

  4. Analysis of Field Data on Computer Failures

    Institute of Scientific and Technical Information of China (English)

    RavishankarK.Iyer; Mei-ChenHsueh

    1990-01-01

    This paper emphasizes the importance of making field measurements for effective and realistic dependability evaluatians.Two examples are given,both based on real data from IBM mainframes.The first evaluates the imnact of the operating environment on system failure characteristics and the second shows how an accurate model depicting this interaction can be extracted from real data.

  5. Analysis of causes of construction failure of road embankments

    Directory of Open Access Journals (Sweden)

    Ryszard Chmielewski

    2016-07-01

    Full Text Available The paper proposes a methodology for conducting the analysis of causes of con-struction failure of road embankments. First of all, it is focused on damaged road embankments, which represent a substantial percentage of this type of failure. At the beginning, current norms, regulations and rules of building art are presented, compliance with which should ensure a proper quality of construction, and thus should also reduce the risk of failure. In the next part, the paper is focused on the juxtaposition of the causes of construction failure of road at various stages of carrying out the investment projects. It is proposed a methodology for evaluating the causes of the construction failure of road and the methodology followed in the event of their occurrence. In the final part, practical applications of analytical results for the selected examples are presented. Keywords: earthworks, road embankments, slopes and embankments, trenches, failure

  6. OH-58 helicopter transmission failure analysis

    Science.gov (United States)

    Townsend, D. P.; Coy, J. J.; Hatvani, B. R.

    1976-01-01

    The OH-58 main transmission gearbox was run at varying output torques, speeds, and oil cooling rates. The gearbox was subsequently run to destruction by draining the oil from the gearbox while operating at a speed of 6200 revs per minute and 36,000 inch-pounds output torque. Primary cause of gearbox failure was overheating and melting of the planet bearing aluminum cages. Complete failure of the gearbox occurred in 28 1/2 minutes after the oil pressure dropped to zero. The alternating and maximum stresses in the gearbox top case were approximately 10 percent of the endurance limit for the material. Deflection of the bevel gear at 67000 inch-pounds output torque indicate a marginal stiffness for the bevel gear supporting system.

  7. Demographic analysis from summaries of an age-structured population

    Science.gov (United States)

    Link, William A.; Royle, J. Andrew; Hatfield, Jeff S.

    2003-01-01

    Demographic analyses of age-structured populations typically rely on life history data for individuals, or when individual animals are not identified, on information about the numbers of individuals in each age class through time. While it is usually difficult to determine the age class of a randomly encountered individual, it is often the case that the individual can be readily and reliably assigned to one of a set of age classes. For example, it is often possible to distinguish first-year from older birds. In such cases, the population age structure can be regarded as a latent variable governed by a process prior, and the data as summaries of this latent structure. In this article, we consider the problem of uncovering the latent structure and estimating process parameters from summaries of age class information. We present a demographic analysis for the critically endangered migratory population of whooping cranes (Grus americana), based only on counts of first-year birds and of older birds. We estimate age and year-specific survival rates. We address the controversial issue of whether management action on the breeding grounds has influenced recruitment, relating recruitment rates to the number of seventh-year and older birds, and examining the pattern of variation through time in this rate.

  8. Survival Analysis of Fatigue and Rutting Failures in Asphalt Pavements

    Directory of Open Access Journals (Sweden)

    Pabitra Rajbongshi

    2016-01-01

    Full Text Available Fatigue and rutting are two primary failure mechanisms in asphalt pavements. The evaluations of fatigue and rutting performances are significantly uncertain due to large uncertainties involved with the traffic and pavement life parameters. Therefore, deterministically it is inadequate to predict when an in-service pavement would fail. Thus, the deterministic failure time which is known as design life (yr of pavement becomes random in nature. Reliability analysis of such time (t dependent random variable is the survival analysis of the structure. This paper presents the survival analysis of fatigue and rutting failures in asphalt pavement structures. It is observed that the survival of pavements with time can be obtained using the bathtub concept that contains a constant failure rate period and an increasing failure rate period. The survival function (S(t, probability density function (pdf, and probability distribution function (PDF of failure time parameter are derived using bathtub analysis. It is seen that the distribution of failure time follows three parametric Weibull distributions. This paper also works out to find the most reliable life (YrR of pavement sections corresponding to any reliability level of survivability.

  9. 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.

  10. Strength Reliability Analysis of Stiffened Cylindrical Shells Considering Failure Correlation

    Institute of Scientific and Technical Information of China (English)

    Xu Bai; Liping Sun; Wei Qin; Yongkun Lv

    2014-01-01

    The stiffened cylindrical shell is commonly used for the pressure hull of submersibles and the legs of offshore platforms. There are various failure modes because of uncertainty with the structural size and material properties, uncertainty of the calculation model and machining errors. Correlations among failure modes must be considered with the structural reliability of stiffened cylindrical shells. However, the traditional method cannot consider the correlations effectively. The aim of this study is to present a method of reliability analysis for stiffened cylindrical shells which considers the correlations among failure modes. Firstly, the joint failure probability calculation formula of two related failure modes is derived through use of the 2D joint probability density function. Secondly, the full probability formula of the tandem structural system is given with consideration to the correlations among failure modes. At last, the accuracy of the system reliability calculation is verified through use of the Monte Carlo simulation. Result of the analysis shows the failure probability of stiffened cylindrical shells can be gained through adding the failure probability of each mode.

  11. FT4 Data Analysis Summary (SSI-ARC)

    Science.gov (United States)

    Isaacson, Douglas R.; Gong, Chester; Reardon, Scott Edward; Santiago, Confesor

    2016-01-01

    Standards for Unmanned Aircraft System (UAS) Detect-and-Avoid (DAA) systems are currently being developed under the auspices of the RTCA Special Committee 228 (SC-228). To support the development of these standards, a series of flight tests has been conducted at NASAs Armstrong Flight Research Center (NASA-AFRC). The fourth in this series of flight test activities (Flight Test 4, or simply FT4) was conducted during the Spring and Summer of 2016. FT4 supported the objectives of numerous organizations working toward UAS DAA Minimum Operational Performance Standards (MOPS) and UAS DAA Radar MOPS. The summary provided herein is limited to the objectives, analysis and conclusions of the NASA Ames Research Center (NASA-ARC) SSI team toward the refinement of UAS DAA MOPS. This document provides a high-level overview of FT4 and the SSI-ARC objectives, a summary of the data analysis methodology and recommendations for UAS DAA MOPS refinements based on the data analysis results. A total of 72 encounters were flown to support SSI-ARC objectives. Test results were generally consistent with acceptable UAS DAA system performance and will be considered in broader SC-228 requirements validation efforts. Observed alert lead times indicated acceptable UAS DAA alerting performance. Effective interoperability between the UAS DAA system and the Traffic Alert and Collision Avoidance System (TCAS) was observed with one notable exception: TCAS Resolutions Advisories (RA) were observed in the absence of any DAA alert on two occasions, indicating the need for alert parameter refinement. Findings further indicated the need for continued work in the areas of DAA Well Clear Recovery logic and alert stability for Mode-C-only intruders. Finally, results demonstrated a high level of compliance with a set of evaluation criteria designed to provide anecdotal evidence of acceptable UAS DAA system performance.

  12. Failure modes and effects analysis (RADL Item 2-23)

    Energy Technology Data Exchange (ETDEWEB)

    None

    1980-04-01

    The Pilot Plant is a central receiver design concept. It is comprised of five major subsystems as shown schematically, plus a set of equipment (Plant Support Subsystem) used to support total plant operation. The failure modes and effects analysis (FMEA) is a bottom-up analysis used to identify the failure characteristics of the system (total equipment used to produce electrical power), that is, the failure of a single component is assumed and the effect of that failure upon the system is determined. The FMEA is concerned with the plant from an operational standpoint (i.e., the production of electrical power). This analysis was performed to the component level. This was interpreted as a valve, computer, measurement sensor and its associated signal conditioning, an electronic black box, etc.

  13. Summary measures for clinical gait analysis: a literature review.

    Science.gov (United States)

    Cimolin, Veronica; Galli, Manuela

    2014-04-01

    Instrumented 3D-gait analysis (3D-GA) is an important method used to obtain information that is crucial for establishing the level of functional limitation due to pathology, observing its evolution over time and evaluating rehabilitative intervention effects. However, a typical 3D-GA evaluation produces a vast amount of data, and despite its objectivity, its use is complicated, and the data interpretation is difficult. It is even more difficult to obtain an overview on patient cohorts for a comparison. Moreover, there is a growing awareness of the need for a concise index, specifically, a single measure of the 'quality' of a particular gait pattern. Several gait summary measures, which have been used in conjunction with 3D-GA, have been proposed to objectify clinical impression, quantify the degree of gait deviation from normal, stratify the severity of pathology, document the changes in gait patterns over time and evaluate interventions.

  14. Linguistic analysis of IPCC summaries for policymakers and associated coverage

    Science.gov (United States)

    Barkemeyer, Ralf; Dessai, Suraje; Monge-Sanz, Beatriz; Renzi, Barbara Gabriella; Napolitano, Giulio

    2016-03-01

    The Intergovernmental Panel on Climate Change (IPCC) Summary for Policymakers (SPM) is the most widely read section of IPCC reports and the main springboard for the communication of its assessment reports. Previous studies have shown that communicating IPCC findings to a variety of scientific and non-scientific audiences presents significant challenges to both the IPCC and the mass media. Here, we employ widely established sentiment analysis tools and readability metrics to explore the extent to which information published by the IPCC differs from the presentation of respective findings in the popular and scientific media between 1990 and 2014. IPCC SPMs clearly stand out in terms of low readability, which has remained relatively constant despite the IPCC’s efforts to consolidate and readjust its communications policy. In contrast, scientific and quality newspaper coverage has become increasingly readable and emotive. Our findings reveal easy gains that could be achieved in making SPMs more accessible for non-scientific audiences.

  15. Failure analysis of air fan blades

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-qing; JI Zhe; CUI Yong-li; CUI Chun-zhi; SUN Zhi

    2008-01-01

    The failure of all 12 blades of an air fan was investigated by metallurgical and mechanical experiments and an examina-tion of the fracture surface. The experimental results show that the cast aluminium-silicon alloy without any modification had a number of material defects, such as coarse grains, a loose structure, a large number of shrinkage holes, a long and thin bold-pin shaped silicon-phase, poor material strength and serious brittleness. In addition, installed on the spindle without elastic conjunction,blade No. 10 vibrated and inevitably.spun off due to the large centrifugal force. Therefore, blade No. 10 first cracked at the locking handle, then broke at the root, which caused all the other 11 blades to be broken by the crack of blade No.10.

  16. 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.

  17. PCA oversedation: application of Healthcare Failure Mode Effect (HFMEA) Analysis.

    Science.gov (United States)

    Cronrath, Pam; Lynch, Timothy W; Gilson, Linda J; Nishida, Carol; Sembar, M Colleen; Spencer, Patricia J; West, Daidre Foote

    2011-01-01

    Hospital systems utilize many varied problem-solving processes to address system improvements and ensure patient safety. The Healthcare Failure Mode Effect Analysis (HFMEA) model is one of these tools and uses a multidisciplinary team to look at processes, diagramming the steps involved to identify potential failure points. The application of the HFMEA model allowed one large health care system to address a complex process by prioritizing proactive change improvements in order to prevent postoperative patient-controlled anesthesia oversedation events. The changes implemented identified 16 failure points with a hazard score of 16 or greater. One year later, the established system HFMEA goal was met: oversedation events were reduced by 50%.

  18. 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.

  19. 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.

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

    NARCIS (Netherlands)

    Sozer, Hasan; Tekinerdogan, Bedir; Aksit, Mehmet; Lemos, de 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.

  1. Storage Reliability of Missile Materiel Program. Storage Reliability Analysis Summary Report. Volume 1. Electrical and Electronic Devices

    Science.gov (United States)

    1976-05-01

    Donald R. Earles .. FOR , HEADQUARTERS , U. S. ARMY MISSILE COMMAND REDSTONE ARSENAL, ALABAMA IN COMPLIANCE WITH CONTRACT NO. DAAHOI-74-C-0853 DATED 4...not available. Data storage failure modes is mucl . less extensive. A summary of the failure modes is shown in Table 4.1-2. 4.1.2 Non-Operational Failure

  2. Early failure of bioabsorbable anterior cervical fusion plates: case report and failure analysis.

    Science.gov (United States)

    Brkaric, Mario; Baker, Kevin C; Israel, Raj; Harding, Trevor; Montgomery, David M; Herkowitz, Harry N

    2007-05-01

    Case report with forensic failure analysis. To determine the failure modes of 3 explanted 70:30 PLDLA Mystique (Medtronic Sofamor Danek, Memphis, TN) graft containment plates retrieved from revision surgery for early device failure. To reduce the problems of stress-shielding and radiopacity associated with metallic systems, bioabsorbable polymers have been used in anterior cervical discectomy and fusion procedures. Degradation of mechanical properties in vivo is a major concern when using bioabsorbable systems. Three of 6 patients who underwent anterior cervical discectomy with instrumented fusion, using Mystique graft containment systems experienced early failure requiring revision to alternate hardware. Devices were retrieved after failure and analyzed by light microscopy and environmental scanning electron microscopy. Simulations were performed with an unused plating system to induce damage for comparison with the retrieved devices. A detailed case review was performed to identify possible sources of extraordinary loading or damage. One plating system failed at 6 weeks postimplantation due to fatigue fracture of the screws. Crack initiation sites were identified at the interface of the thread root and mold line of the screw. Another plating system failed at 16 weeks postimplantation due to the coalescence of radial microcracking between holes in the plate, leading to catastrophic failure of the plate. The final plating system failed during the implantation surgery, when the screw fractured in torsion. Stress concentrations at the screw head-shaft interface and thread-shaft interface reduce the fatigue performance of bioabsorbable screws. Hydrolysis of the polymer may also play a role in the reduction of resistance to crack initiation and propagation.

  3. 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.

  4. Energy analysis for damage and catastrophic failure of rocks

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The development history and current state of studies on the characteristics and mechanisms of deformation and failure of rock materials were briefly reviewed from the viewpoint of energy.The main scope and the achievable objectives of the energy-based research system were expatiated.It was validated by experiments that the damage process of rocks can be well described by the rock damage evolution equation established based on energy dissipation.It was found from the uniaxial compression and biaxial compression tests that only a small proportion of the total input energy in hard rocks is dissipated before peak load and a large proportion in soft rocks is dissipated before peak load.For both hard and soft rocks,the energy dissipated after peak load accounts for a greater proportion.More energy would be required for rock failure under equal biaxial compression than under unequal biaxial compression.The total absorbed energy is different for rock failure under high-rate loading and low-rate loading.More fragmented failure pattern usually corresponds to higher energy absorption.The mesoscopic analysis on the damage and failure of bedded salt rocks showed that the energy dissipation is prominent and the total absorbed energy for rock failure is low when cracks propagate in the weak mud interlayer while it is contrary when cracks propagate in the salt rock.The energy accumulation,transfer,dissipation and release during the failure process of tunnel with impending failure under disturbance were analyzed theoretically based on the elastoplastic mechanics theory.Furthermore,the spatial distribution of energy dissipation and energy release of fractured rocks under unloading was simulated numerically.It was demonstrated that energy is likely to be released from the weakest surface under compression,which triggers the global failure of rocks.

  5. Probabilistic Nonlinear Analysis of Reinforced Concrete Bubbler Tower Structure Failure

    Directory of Open Access Journals (Sweden)

    Králik Juraj

    2014-06-01

    Full Text Available This paper describes the reliability analysis of concrete bubbler tower structure of nuclear power plant with the reactor WWER 440 under high internal overpressure. There is showed summary of calculation models and calculation methods for the probability analysis of the structural integrity considering degradation effects and high internal overpressure. The uncertainties of the resistance and the calculation model were taking in the account in the RSM method.

  6. The quantitative failure of human reliability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, C.T.

    1995-07-01

    This philosophical treatise argues the merits of Human Reliability Analysis (HRA) in the context of the nuclear power industry. Actually, the author attacks historic and current HRA as having failed in informing policy makers who make decisions based on risk that humans contribute to systems performance. He argues for an HRA based on Bayesian (fact-based) inferential statistics, which advocates a systems analysis process that employs cogent heuristics when using opinion, and tempers itself with a rational debate over the weight given subjective and empirical probabilities.

  7. 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...

  8. Northern Marshall Islands radiological survey: sampling and analysis summary

    Energy Technology Data Exchange (ETDEWEB)

    Robison, W.L.; Conrado, C.L.; Eagle, R.J.; Stuart, M.L.

    1981-07-23

    A radiological survey was conducted in the Northern Marshall Islands to document reamining external gamma exposures from nuclear tests conducted at Enewetak and Bikini Atolls. An additional program was later included to obtain terrestrial and marine samples for radiological dose assessment for current or potential atoll inhabitants. This report is the first of a series summarizing the results from the terrestrial and marine surveys. The sample collection and processing procedures and the general survey methodology are discussed; a summary of the collected samples and radionuclide analyses is presented. Over 5400 samples were collected from the 12 atolls and 2 islands and prepared for analysis including 3093 soil, 961 vegetation, 153 animal, 965 fish composite samples (average of 30 fish per sample), 101 clam, 50 lagoon water, 15 cistern water, 17 groundwater, and 85 lagoon sediment samples. A complete breakdown by sample type, atoll, and island is given here. The total number of analyses by radionuclide are 8840 for /sup 241/Am, 6569 for /sup 137/Cs, 4535 for /sup 239 +240/Pu, 4431 for /sup 90/Sr, 1146 for /sup 238/Pu, 269 for /sup 241/Pu, and 114 each for /sup 239/Pu and /sup 240/Pu. A complete breakdown by sample category, atoll or island, and radionuclide is also included.

  9. 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.

  10. Failure modes and effects analysis of fusion magnet systems

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Summary of Prometheus Radiation Shielding Nuclear Design Analysis

    Energy Technology Data Exchange (ETDEWEB)

    J. Stephens

    2006-01-13

    This report transmits a summary of radiation shielding nuclear design studies performed to support the Prometheus project. Together, the enclosures and references associated with this document describe NRPCT (KAPL & Bettis) shielding nuclear design analyses done for the project.

  12. Summary oral reflective analysis: a method for interview data analysis in feminist qualitative research.

    Science.gov (United States)

    Thompson, S M; Barrett, P A

    1997-12-01

    This article explores an innovative approach to qualitative data analysis called Summary Oral Reflective Analysis (SORA). The method preserves the richness and contextuality of in-depth interview data within a broader feminist philosophical perspective. This multidisciplinary approach was developed in two individual research programs within a cooperative, collaborative arrangement. It represents a creative response to perceived deficiencies in the pragmatics of qualitative data analysis where the maintenance of data contextuality is critical.

  13. Statistical analysis of cascading failures in power grids

    Energy Technology Data Exchange (ETDEWEB)

    Chertkov, Michael [Los Alamos National Laboratory; Pfitzner, Rene [Los Alamos National Laboratory; Turitsyn, Konstantin [Los Alamos National Laboratory

    2010-12-01

    We introduce a new microscopic model of cascading failures in transmission power grids. This model accounts for automatic response of the grid to load fluctuations that take place on the scale of minutes, when optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, caused by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systems consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascading outages over real-world power networks are discussed.

  14. Reliability test and failure analysis of high power LED packages*

    Institute of Scientific and Technical Information of China (English)

    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 ℃/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.

  15. Failure Analysis in Development & Manufacture for Customer

    Directory of Open Access Journals (Sweden)

    Darina Juhaszova

    2013-12-01

    Full Text Available Purpose of the article is to present partial results of research solutions in the doctoral thesis Risk Management of customer driven projects. Background is the data from the organization Johnson Controls Inc., s.r.o. – OZ Trencin, presented as a case study. The overall aim is to identify and reduce project risks which are considered as decisive steps in managing successful projects. The principle is based on mapping current literature on risk management as many of problems that currently exist with respect to various projects such as delay, framework changes and even cancellation or revocation of the project may be due to inefficient risk management. The solution is the FMEA method. In order to use this type of risk analysis, the values of severity, occurrence and detection are standard values of FMEA slightly modified according to the guidelines of the organization. The result is presented as a case study in the final section of the article.

  16. Low temperature fusion wafer bonding quality investigation for failure mode analysis

    NARCIS (Netherlands)

    Dragoi, V.; Czurratis, P.; Brand, S.; Beyersdorfer, J.; Patzig, C.; Krugers, J.P.; Schrank, F.; Siegert, J.; Petzold, M.

    2012-01-01

    In this paper, a brief summary of potential defect formation and failure characteristics for low temperature plasma-assisted Si wafer bonding in correlation to different influencing factors is given. In terms of a failure catalogue classification, these defects are related to incoming material quali

  17. Low temperature fusion wafer bonding quality investigation for failure mode analysis

    NARCIS (Netherlands)

    Dragoi, V.; Czurratis, P.; Brand, S.; Beyersdorfer, J.; Patzig, C.; Krugers, J.P.; Schrank, F.; Siegert, J.; Petzold, M.

    2012-01-01

    In this paper, a brief summary of potential defect formation and failure characteristics for low temperature plasma-assisted Si wafer bonding in correlation to different influencing factors is given. In terms of a failure catalogue classification, these defects are related to incoming material

  18. Low temperature fusion wafer bonding quality investigation for failure mode analysis

    NARCIS (Netherlands)

    Dragoi, V.; Czurratis, P.; Brand, S.; Beyersdorfer, J.; Patzig, C.; Krugers, J.P.; Schrank, F.; Siegert, J.; Petzold, M.

    2012-01-01

    In this paper, a brief summary of potential defect formation and failure characteristics for low temperature plasma-assisted Si wafer bonding in correlation to different influencing factors is given. In terms of a failure catalogue classification, these defects are related to incoming material quali

  19. Hope in elderly adults with chronic heart failure. Concept analysis.

    Science.gov (United States)

    Caboral, Meriam F; Evangelista, Lorraine S; Whetsell, Martha V

    2012-01-01

    This topic review employed Walker and Avant's method of concept analysis to explore the construct of hope in elderly adults with chronic heart failure. The articles analyzed revealed that hope, as the belief of the occurrence of a positive result without any guarantee that it will be produced, is necessary for the survival and wellbeing of the elderly adults enduring this disease.

  20. Bank stability analysis for fluvial erosion and mass failure

    Science.gov (United States)

    The central objective of this study was to highlight the differences in magnitude between mechanical and fluvial streambank erosional strength with the purpose of developing a more comprehensive bank stability analysis. Mechanical erosion and ultimately failure signifies the general movement or coll...

  1. Rooting out causes in failure analysis; Risk analysis

    Energy Technology Data Exchange (ETDEWEB)

    Keith, Graeme

    2010-07-01

    The Deepwater Horizon disaster was a terrible reminder of the consequences of equipment failure on facilities operating in challenging environments. Thankfully catastrophes on the scale of the Deepwater Horizon are rare, but equipment failure is a daily occurrence on installations around the globe. The consequences range from short unexpected downtime, to a total stop on production. from a brief burst of flaring to lasting environmental damage and from the momentary discomfiture of a worker to incapability or death. (Author)

  2. 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

  3. [Failure mode and effect analysis: application in chemotherapy].

    Science.gov (United States)

    Chuang, Ching-Hui; Chuang, Sheu-Wen

    2009-08-01

    Medical institutions are increasingly concerned about ensuring the safety of patients under their care. Failure mode and effect analysis (FMEA) is a qualitative approach based on a proactive process. Strongly promoted by the Joint Commission Accredited of Health Organization (JCAHO) since 2002, FMEA has since been adopted and widely practiced in healthcare organizations to assess and analyze clinical error events. FMEA has proven to be an effective method of minimizing errors in both manufacturing and healthcare industries. It predicts failure points in systems and allows an organization to address proactively the causes of problems and prioritize improvement strategies. The application of FMEA in chemotherapy at our department identified three main failure points: (1) inappropriate chemotherapy standard operating procedures (SOPs), (2) communication barriers, and (3) insufficient training of nurses. The application of FMEA in chemotherapy is expected to enhance the sensitivity and proactive abilities of healthcare practitioners during potentially risky situations as well as to improve levels of patient care safety.

  4. Augmenting health care failure modes and effects analysis with simulation

    DEFF Research Database (Denmark)

    Staub-Nielsen, Ditte Emilie; Dieckmann, Peter; Mohr, Marlene

    2014-01-01

    This study explores whether simulation plays a role in health care failure mode and effects analysis (HFMEA); it does this by evaluating whether additional data are found when a traditional HFMEA is augmented with simulation. Two multidisciplinary teams identified vulnerabilities in a process...... for deeper analysis. The study indicates that simulation has a role in HFMEA. Both ways of using simulation seemed feasible, and our results are not conclusive in selecting one over the other....

  5. User-oriented summary extraction for soccer video based on multimodal analysis

    Science.gov (United States)

    Liu, Huayong; Jiang, Shanshan; He, Tingting

    2011-11-01

    An advanced user-oriented summary extraction method for soccer video is proposed in this work. Firstly, an algorithm of user-oriented summary extraction for soccer video is introduced. A novel approach that integrates multimodal analysis, such as extraction and analysis of the stadium features, moving object features, audio features and text features is introduced. By these features the semantic of the soccer video and the highlight mode are obtained. Then we can find the highlight position and put them together by highlight degrees to obtain the video summary. The experimental results for sports video of world cup soccer games indicate that multimodal analysis is effective for soccer video browsing and retrieval.

  6. Reliability analysis of retaining walls with multiple failure modes

    Institute of Scientific and Technical Information of China (English)

    张道兵; 孙志彬; 朱川曲

    2013-01-01

    In order to reduce the errors of the reliability of the retaining wall structure in the establishment of function, in the estimation of parameter and algorithm, firstly, two new reliability and stability models of anti-slipping and anti-overturning based on the upper-bound theory of limit analysis were established, and two kinds of failure modes were regarded as a series of systems with multiple correlated failure modes. Then, statistical characteristics of parameters of the retaining wall structure were inferred by maximal entropy principle. At last, the structural reliabilities of single failure mode and multiple failure modes were calculated by Monte Carlo method in MATLAB and the results were compared and analyzed on the sensitivity. It indicates that this method, with a high precision, is not only easy to program and quick in calculation, but also without the limit of nonlinear functions and non-normal random variables. And the results calculated by this method which applies both the limit analysis theory, maximal entropy principle and Monte Carlo method into analyzing the reliability of the retaining wall structures is more scientific, accurate and reliable, in comparison with those calculated by traditional method.

  7. Experimental and failure analysis of the prosthetic finger joint implants

    Science.gov (United States)

    Naidu, Sanjiv H.

    Small joint replacement arthroplasty of the hand is a well accepted surgical procedure to restore function and cosmesis in an individual with a crippled hand. Silicone elastomers have been used as prosthetic material in various small hand joints for well over three decades. Although the clinical science aspects of silicone elastomer failure are well known, the physical science aspects of prosthetic failure are scant and vague. In the following thesis, using both an animal model, and actual retrieved specimens which have failed in human service, experimental and failure analysis of silicone finger joints are presented. Fractured surfaces of retrieved silicone trapezial implants, and silicone finger joint implants were studied with both FESEM and SEM; the mode of failure for silicone trapezium is by wear polishing, whereas the finger joint implants failed either by fatigue fracture or tearing of the elastomer, or a combination of both. Thermal analysis revealed that the retrieved elastomer implants maintained its viscoelastic properties throughout the service period. In order to provide for a more functional and physiologic arthroplasty a novel finger joint (Rolamite prosthesis) is proposed using more recently developed thermoplastic polymers. The following thesis also addresses the outcome of the experimental studies of the Rolamite prosthesis in a rabbit animal model, in addition to the failure analysis of the thermoplastic polymers while in service in an in vivo synovial environment. Results of retrieved Rolamite specimens suggest that the use for thermoplastic elastomers such as block copolymer based elastomers in a synovial environment such as a mammalian joint may very well be limited.

  8. [Primary failure of eruption (PFE). Clinical and molecular genetics analysis].

    Science.gov (United States)

    Stellzig-Eisenhauer, Angelika; Decker, Eva; Meyer-Marcotty, Philipp; Rau, Christiane; Fiebig, Britta S; Kress, Wolfram; Saar, Kathrin; Rüschendorf, Franz; Hubner, Norbert; Grimm, Tiemo; Witt, Emil; Weber, Bernhard H F

    2013-09-01

    The term "primary failure of eruption" (PFE) refers to the complete or partial failure of a primary non-ankylosed tooth to erupt due to a disturbance of the eruption mechanism. Up to now, the molecular basis for this failure was unknown. Four families were studied in whom at least two members were affected by non-syndromic PFE as part of a clinical and molecular genetics study. Radiological diagnostics (OPTs) were carried out in all patients and their unaffected relatives (control group). The genetic analysis included a genomewide linkage analysis followed by direct DNA sequencing of positional candidate genes. Starting from the index patients, we were able to reconstruct pedigrees over two and/or three generations in the families that indicated an autosomal-dominant mode of inheritance of non-syndromic PFE. Fifteen patients were diagnosed with PFE. Gender distribution was nearly equal (7 female, 8 male). Molecular genetic analysis of the PTHR1 gene revealed three distinct heterozygous mutations (c.1050-3C>G; c.543 + 1G>A; c.463G>T). Unaffected persons exhibited no mutations. Knowledge of the genetic causes of non-syndromic PFE can now be used for the differential diagnosis of eruption failure. It permits affected family members to be identified early and may lead to new treatment possibilities in the long term. The genetically-verified diagnosis of "primary failure of eruption" can protect patients and orthodontists from years of futile treatment, because orthodontic treatment alone does not lead to success. Moreover, it has a negative influence on unaffected teeth and areas of the jaw. © EDP Sciences, SFODF, 2013.

  9. Assessing short summaries with human judgments procedure and latent semantic analysis in narrative and expository texts.

    Science.gov (United States)

    León, José A; Olmos, Ricardo; Escudero, Inmaculada; Cañas, José J; Salmerón, Lalo

    2006-11-01

    In the present study, we tested a computer-based procedure for assessing very concise summaries (50 words long) of two types of text (narrative and expository) using latent semantic analysis (LSA) in comparison with the judgments of four human experts. LSA was used to estimate semantic similarity using six different methods: four holistic (summary-text, summary-summaries, summary-expert summaries, and pregraded-ungraded summary) and two componential (summary-sentence text and summary-main sentence text). A total of 390 Spanish middle and high school students (14-16 years old) and six experts read a narrative or expository text and later summarized it. The results support the viability of developing a computerized assessment tool using human judgments and LSA, although the correlation between human judgments and LSA was higher in the narrative text than in the expository, and LSA correlated more with human content ratings thanwith hu mancoherence ratings. Finally, theholistic methods were found to be more reliable than the componential methods analyzed in this study.

  10. Root Cause Failure Analysis of Stator Winding Insulation failure on 6.2 MW hydropower generator

    Science.gov (United States)

    Adhi Nugroho, Agus; Widihastuti, Ida; Ary, As

    2017-04-01

    Insulation failure on generator winding insulation occurred in the Wonogiri Hydropower plant has caused stator damage since ase was short circuited to ground. The fault has made the generator stop to operate. Wonogiri Hydropower plant is one of the hydroelectric plants run by PT. Indonesia Power UBP Mrica with capacity 2 × 6.2 MW. To prevent damage to occur again on hydropower generators, an analysis is carried out using Root Cause Failure Analysis RCFA is a systematic approach to identify the root cause of the main orbasic root cause of a problem or a condition that is not wanted. There are several aspects to concerned such as: loading pattern and operations, protection systems, generator insulation resistance, vibration, the cleanliness of the air and the ambient air. Insulation damage caused by gradual inhomogeneous cooling at the surface of winding may lead in to partial discharge. In homogeneous cooling may present due to lattice hampered by dust and oil deposits. To avoid repetitive defects and unwanted condition above, it is necessary to perform major maintenance overhaul every 5000-6000 hours of operation.

  11. 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.

  12. Fault tree analysis of most common rolling bearing tribological failures

    Science.gov (United States)

    Vencl, Aleksandar; Gašić, Vlada; Stojanović, Blaža

    2017-02-01

    Wear as a tribological process has a major influence on the reliability and life of rolling bearings. Field examinations of bearing failures due to wear indicate possible causes and point to the necessary measurements for wear reduction or elimination. Wear itself is a very complex process initiated by the action of different mechanisms, and can be manifested by different wear types which are often related. However, the dominant type of wear can be approximately determined. The paper presents the classification of most common bearing damages according to the dominant wear type, i.e. abrasive wear, adhesive wear, surface fatigue wear, erosive wear, fretting wear and corrosive wear. The wear types are correlated with the terms used in ISO 15243 standard. Each wear type is illustrated with an appropriate photograph, and for each wear type, appropriate description of causes and manifestations is presented. Possible causes of rolling bearing failure are used for the fault tree analysis (FTA). It was performed to determine the root causes for bearing failures. The constructed fault tree diagram for rolling bearing failure can be useful tool for maintenance engineers.

  13. Measurement and Analysis of Failures in Computer Systems

    Science.gov (United States)

    Thakur, Anshuman

    1997-01-01

    This thesis presents a study of software failures spanning several different releases of Tandem's NonStop-UX operating system running on Tandem Integrity S2(TMR) systems. NonStop-UX is based on UNIX System V and is fully compliant with industry standards, such as the X/Open Portability Guide, the IEEE POSIX standards, and the System V Interface Definition (SVID) extensions. In addition to providing a general UNIX interface to the hardware, the operating system has built-in recovery mechanisms and audit routines that check the consistency of the kernel data structures. The analysis is based on data on software failures and repairs collected from Tandem's product report (TPR) logs for a period exceeding three years. A TPR log is created when a customer or an internal developer observes a failure in a Tandem Integrity system. This study concentrates primarily on those TPRs that report a UNIX panic that subsequently crashes the system. Approximately 200 of the TPRs fall into this category. Approximately 50% of the failures reported are from field systems, and the rest are from the testing and development sites. It has been observed by Tandem developers that fewer cases are encountered from the field than from the test centers. Thus, the data selection mechanism has introduced a slight skew.

  14. Failure mode and effects analysis: too little for too much?

    Science.gov (United States)

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

    2012-07-01

    Failure mode and effects analysis (FMEA) is a structured prospective risk assessment method that is widely used within healthcare. FMEA involves a multidisciplinary team mapping out a high-risk process of care, identifying the failures that can occur, and then characterising each of these in terms of probability of occurrence, severity of effects and detectability, to give a risk priority number used to identify failures most in need of attention. One might assume that such a widely used tool would have an established evidence base. This paper considers whether or not this is the case, examining the evidence for the reliability and validity of its outputs, the mathematical principles behind the calculation of a risk prioirty number, and variation in how it is used in practice. We also consider the likely advantages of this approach, together with the disadvantages in terms of the healthcare professionals' time involved. We conclude that although FMEA is popular and many published studies have reported its use within healthcare, there is little evidence to support its use for the quantitative prioritisation of process failures. It lacks both reliability and validity, and is very time consuming. We would not recommend its use as a quantitative technique to prioritise, promote or study patient safety interventions. However, the stage of FMEA involving multidisciplinary mapping process seems valuable and work is now needed to identify the best way of converting this into plans for action.

  15. Failure Mode and Effect Analysis of Subsea Multiphase Pump Equipment

    Directory of Open Access Journals (Sweden)

    Oluwatoyin Shobowale Kafayat

    2014-07-01

    Full Text Available Finding oil and gas reserves in deep/harsh environment with challenging reservoir and field conditions, subsea multiphase pumping benefits has found its way to provide solutions to these issues. Challenges such as failure issues that are still surging the industry and with the current practice of information hiding, this issues becomes even more difficult to tackle. Although, there are some joint industry projects which are only accessible to its members, still there is a need to have a clear understanding of these equipment groups so as to know which issues to focus attention on. A failure mode and effect analysis (FMEA is a potential first aid in understanding this equipment groups. A survey questionnaire/interview was conducted with the oil and gas operating company and equipment manufacturer based on the literature review. The results indicates that these equipment’s group are similar with its onshore counterpart, but the difference is the robustness built into the equipment internal subsystems for subsea applications. The results from the manufacturer perspectives indicates that Helico-axial multiphase pump have a mean time to failure of more than 10 years, twin-screw and electrical submersible pumps are still struggling with a mean time to failure of less than 5 years.

  16. Defining Human Failure Events for Petroleum Risk Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring; Knut Øien

    2014-06-01

    In this paper, an identification and description of barriers and human failure events (HFEs) for human reliability analysis (HRA) is performed. The barriers, called target systems, are identified from risk significant accident scenarios represented as defined situations of hazard and accident (DSHAs). This report serves as the foundation for further work to develop petroleum HFEs compatible with the SPAR-H method and intended for reuse in future HRAs.

  17. Failure Analysis Seminar: Techniques and Teams. Seminar Notes. Volume I.

    Science.gov (United States)

    1981-01-01

    and Progress - Evaluate 7* 6 *~ 0 6 9 9 S 9 FAILURE ANALYSIS STRATEGY1 Augustine E. Magistro *. Introduction A primary task of management and systems...by Augustine Magistro , Picatinny Arsenal and Lawrence R. Seggel, U. S. Army Missile Command. The report Is available from the National Technical...to emphasize techniques - Identification and improvement of your leadership styles 2I BIOGRAPHIC SKETCHES: A.E. "Gus" Magistro - Systems Evaluation

  18. Water Ingress Failure Analysis of Whistler II Unit

    Science.gov (United States)

    2014-08-01

    be addressed to reduce the risk of water ingress. 15. SUBJECT TERMS Failure Analysis, Water Ingress, Ingress Protection, Rain Test 16. SECURITY...conversion coated and should not have been subject to corrosion with exposure to ordinary rain water . The batteries were highly corroded, and some...steel/chromate conversion coated. Corrosion of the star washers was greater than would be expected by normal rain water at normal temperatures

  19. 2014 TRI National Analysis: Toxic Release Inventory Releases at Various Summary Levels

    Data.gov (United States)

    U.S. Environmental Protection Agency — The TRI National Analysis is EPA's annual interpretation of TRI data at various summary levels. It highlights how toxic chemical wastes were managed, where toxic...

  20. 2015 TRI National Analysis: Toxics Release Inventory Releases at Various Summary Levels

    Data.gov (United States)

    U.S. Environmental Protection Agency — The TRI National Analysis is EPA's annual interpretation of TRI data at various summary levels. It highlights how toxic chemical wastes were managed, where toxic...

  1. The Analysis of the Pragmatic Failure in Intercultural communication

    Institute of Scientific and Technical Information of China (English)

    郑彤

    2005-01-01

    pragmatic failure is one of the key reasons which result in intercultural communicative failure. There are two types of pragmatic failure: Pragma-linguistic failure and Socio-pragmatic failure. The solutions to the problem are to have an understanding of cultural differences and to strengthen the understanding and the sensitivity to the culture of target language.

  2. Failure mode and effects analysis outputs: are they valid?

    Directory of Open Access Journals (Sweden)

    Shebl Nada

    2012-06-01

    Full Text Available Abstract Background 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. Methods 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. Results 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. Conclusion 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

  3. Analysis of surface insulation resistance related failures in electronics by circuit simulation

    DEFF Research Database (Denmark)

    Verdingovas, Vadimas; Joshy, Salil; Jellesen, Morten Stendahl

    2017-01-01

    Purpose-The purpose of this study is to show that the humidity levels for surface insulation resistance (SIR)-related failures are dependent on the type of activators used in no-clean flux systems and to demonstrate the possibility of simulating the effects of humidity and contamination on printed...... for the circuit analysis. The SIR data were compared to the surface resistance values observable on a real device printed circuit board assembly. SIR issues at the component and circuit levels were analysed on the basis of parasitic circuit effects owing to the formation of a water layer as an electrical...... conduction medium. Findings-This paper provides a summary of the effects of contamination with various weak organic acids representing the active components in no-clean solder flux residue, and demonstrates the effect of humidity and contamination on the possible malfunctions and errors in electronic...

  4. A case study on engineering failure analysis of link chain.

    Science.gov (United States)

    Kim, Tae-Gu; Lee, Seong-Beom; Lee, Hong-Chul

    2010-09-01

    The objective of this study was to investigate the effect of chain installation condition on stress distribution that could eventually cause disastrous failure from sudden deformation and geometric rupture. Fractographic method used for the failed chain indicates that over-stress was considered as the root cause of failure. 3D modeling and finite element analysis for the chain, used in a crane hook, were performed with a three-dimensional interactive application program, CATIA, commercial finite element analysis and computational fluid dynamic software, ANSYS. The results showed that the state of stress was changed depending on the initial position of the chain that was installed in the hook. Especially, the magnitude of the stress was strongly affected by the bending forces, which are 2.5 times greater (under the simulation condition currently investigated) than that from the plain tensile load. Also, it was noted that the change of load state is strongly related to the failure of parts. The chain can hold an ultimate load of about 8 tons with only the tensile load acting on it. The conclusions of this research clearly showed that a reduction of the loss from similar incidents can be achieved when an operator properly handles the installation of the chain.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Uncertainty Analysis via Failure Domain Characterization: Polynomial Requirement Functions

    Science.gov (United States)

    Crespo, Luis G.; Munoz, Cesar A.; Narkawicz, Anthony J.; Kenny, Sean P.; Giesy, Daniel P.

    2011-01-01

    This paper proposes an uncertainty analysis framework based on the characterization of the uncertain parameter space. This characterization enables the identification of worst-case uncertainty combinations and the approximation of the failure and safe domains with a high level of accuracy. Because these approximations are comprised of subsets of readily computable probability, they enable the calculation of arbitrarily tight upper and lower bounds to the failure probability. A Bernstein expansion approach is used to size hyper-rectangular subsets while a sum of squares programming approach is used to size quasi-ellipsoidal subsets. These methods are applicable to requirement functions whose functional dependency on the uncertainty is a known polynomial. Some of the most prominent features of the methodology are the substantial desensitization of the calculations from the uncertainty model assumed (i.e., the probability distribution describing the uncertainty) as well as the accommodation for changes in such a model with a practically insignificant amount of computational effort.

  7. Analysis of Service Recovery Failure: From Minority Perspective

    National Research Council Canada - National Science Library

    Yasemin Öcal Atınç

    2016-01-01

    .... Previous literature provided insights regarding the perception of service failures by minorities and the challenge of recovery due to racial implications driven from the failure, however lacked...

  8. Study on failure analysis of array chip components in IRFPA

    Science.gov (United States)

    Zhang, Xiaonan; He, Yingjie; Li, Jinping

    2016-10-01

    Infrared focal plane array detector has advantages of strong anti-interference ability and high sensitivity. Its size, weight and power dissipation has been noticeably decreased compared to the conventional infrared imaging system. With the development of the detector manufacture technology and the cost reduction, IRFPA detector has been widely used in the military and commercial fields. Due to the restricting of array chip manufacturing process and material defects, the fault phenomenon such as cracking, bad pixel and abnormal output was showed during the test, which restricts the performance of the infrared detector imaging system, and these effects are gradually intensified with the expanding of the focal plane array size and the shrinking of the pixel size. Based on the analysis of the test results for the infrared detector array chip components, the fault phenomenon was classified. The main cause of the chip component failure is chip cracking, bad pixel and abnormal output. The reason of the failure has been analyzed deeply. According to analyze the mechanism of the failure, a series of measures which contain filtrating materials and optimizing the manufacturing process of array chip components were used to improve the performance of the chip components and the test pass rate, which is used to meet the needs of the detector performance.

  9. Failure analysis of crush hammers based on damage fracture energy

    Institute of Scientific and Technical Information of China (English)

    HUANG Jun-ping; ZHOU Hong-yi; BAI Zhan-wei; YIN Yi-zhong

    2009-01-01

    To prolong the life-span of crush hammers in the pyrite concentrate workplace of Ganbazi Coal Preparation Plant of Chongqing Nantong Mining Ltd., we used a progressive damage constitutive model based on the ductile and shear damage fracture energy to analyze the hammer wear failure caused by the impact and abrasion on the hammer surface by pyrite, and carried out simulation analysis with the explicit algorithm on hammer leftovers from the plant during the process of coarser pyrite comminution. The simulation results are consistent with hammer wear failure caused by pyrite impact. Then we proposed corrective measures to prolong hammer life-span. Results of the production test in the Ganbazi Coal Preparation Plant showed that non-clearance hammers can avoid wear erosion, and adding steel bonded tungsten carbides F3002 prolonged the hammer life-span. The effect of austenitic manganese steel work-hardening was not prominent. Therefore, the hammer failure was mainly caused by superficial abrasion instead of fatigue cracks appearing when grains acted on the hardening layer.

  10. Failure analysis of resin composite bonded to ceramic.

    Science.gov (United States)

    Della Bona, Alvaro; Anusavice, Kenneth J; Mecholsky, John J

    2003-12-01

    To use fractographic principles to classify the mode of failure of resin composite bonded to ceramic specimens after microtensile testing. A leucite-based ceramic (IPS Empress)-E1) and a lithia disilicate-based ceramic (IPS Empress2)-E2) were selected for the study. Fifteen blocks of E1 and E2 were polished through 1 microm alumina abrasive. The following ceramic surface treatments were applied to three blocks of each ceramic: (1) 9.5% hydrofluoric acid (HF) for 2 min; (2) 4% acidulated phosphate fluoride (APF) for 2 min; (3) Silane coating (S); (4) HF+S; (5) APF+S. An adhesive resin and a resin composite were applied to all treated surfaces and light cured. Twenty bar specimens for each group were prepared from the composite-ceramic blocks and stored in 37 degrees C distilled water for 30 days before loading to failure under tension in an Instron testing machine. Fracture surfaces were examined using scanning electron microscopy and X-ray dot mapping. Statistical analysis was performed using one-way ANOVA, Duncan's multiple range test, and Weibull analyses. Similar surface treatments were associated with significantly different bond strengths and modes of failures for E1 and E2. All fractures occurred within the adhesion zone. The microstructural difference between etched E1 and E2 ceramics was a major controlling factor on adhesion. The quality of the bond should not be assessed based on bond strength data alone. Mode of failure and fractographic analyses should provide important information leading to predictions of clinical performance limits.

  11. Lithographic chip identification: meeting the failure analysis challenge

    Science.gov (United States)

    Perkins, Lynn; Riddell, Kevin G.; Flack, Warren W.

    1992-06-01

    This paper describes a novel method using stepper photolithography to uniquely identify individual chips for permanent traceability. A commercially available 1X stepper is used to mark chips with an identifier or `serial number' which can be encoded with relevant information for the integrated circuit manufacturer. The permanent identification of individual chips can improve current methods of quality control, failure analysis, and inventory control. The need for this technology is escalating as manufacturers seek to provide six sigma quality control for their products and trace fabrication problems to their source. This need is especially acute for parts that fail after packaging and are returned to the manufacturer for analysis. Using this novel approach, failure analysis data can be tied back to a particular batch, wafer, or even a position within a wafer. Process control can be enhanced by identifying the root cause of chip failures. Chip identification also addresses manufacturers concerns with increasing incidences of chip theft. Since chips currently carry no identification other than the manufacturer's name and part number, recovery efforts are hampered by the inability to determine the sales history of a specific packaged chip. A definitive identifier or serial number for each chip would address this concern. The results of chip identification (patent pending) are easily viewed through a low power microscope. Batch number, wafer number, exposure step, and chip location within the exposure step can be recorded, as can dates and other items of interest. An explanation of the chip identification procedure and processing requirements are described. Experimental testing and results are presented, and potential applications are discussed.

  12. Finite element model analysis of thermal failure in connector

    Institute of Scientific and Technical Information of China (English)

    WANG Xin; XU Liang-jun

    2007-01-01

    Thermal analysis and thermal diagnose are important for small power connector especially in electronic devices since their structure is usually compact. In this paper thermal behavior of small power connector was investigated. It was found that the contact resistance increased due to the Joule heating, and that increased contact resistance produced more Joule heating; this mutual action causes the connector to lose efficiency. The thermal distribution in the connector was analyzed using finite element method (FEM). The failure mechanism is discussed. It provides basis for improving the structure. The conclusion was verified by experimental results.

  13. Analysis of corrosion failure of petrochemical pipe elbow

    Institute of Scientific and Technical Information of China (English)

    LI Xiao-yan; L(U) Tao

    2005-01-01

    Corrosive failure is frequently found in petrochemical pipelines which may lead to the leakage of the pipes and even the shutdown of the system. However, the corrosion mechanism is still not well understood due to the complex service environment, e.g. the corrosive fluids and the long term operation at higher temperature. The corrosion behaviour of a petrochemical pipe elbow was evaluated via visual examination and microanalysis with optical microscope and scanning electron microscope(SEM) together with energy dispersive analysis X-ray (EDAX). The corresponding corrosion mechanisms, the combination of grain boundary attach and the crevice attach together with the flow-accelerated corrosion, were proposed consequently.

  14. Failure analysis of axle shaft of a fork lift

    Directory of Open Access Journals (Sweden)

    Souvik Das

    2015-04-01

    Full Text Available An axle shaft of fork lift failed at operation within 296 h of service. The shaft transmits torque from discrepancy to wheel through planetary gear arrangement. A section of fractured axle shaft made of induction-hardened steel was analyzed to determine the root cause of the failure. Optical microscopies as well as field emission gun scanning electron microscopy (FEG-SEM along with energy dispersive spectroscopy (EDS were carried out to characterize the microstructure. Hardness profile throughout the cross-section was evaluated by micro-hardness measurements. Chemical analysis indicated that the shaft was made of 42CrMo4 steel grade as per specification. Microstructural analysis and micro-hardness profile revealed that the shaft was improperly heat treated resulting in a brittle case, where crack was found to initiate from the case in a brittle mode in contrast to ductile mode within the core. This behaviour was related to differences in microstructure, which was observed to be martensitic within the case with a micro-hardness equivalent to 735 HV, and a mixture of non-homogeneous structure of pearlite and ferrite within the core with a hardness of 210 HV. The analysis suggests that the fracture initiated from the martensitic case as brittle mode due to improper heat treatment process (high hardness. Moreover the inclusions along the hot working direction i.e. in the longitudinal axis made the component more susceptible to failure.

  15. D-Zero Nitrogen Dewar Failure Mode and Effects Analysis and "What-If" Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rucisnki, R.A.; /Fermilab

    1990-12-05

    All components related to the nitrogen storage dewar were included. Pipe failures were excluded. Instrument air valves and components were excluded. See the 'What if' analysis for consequences from loss of instrument air.

  16. Country Social Analysis : Ethnicity and Development in Vietnam - Summary report

    OpenAIRE

    World Bank

    2009-01-01

    This report " Country Social Analysis (CSA) " focused on ethnicity and development in Vietnam is a provocative analysis of marginality in contemporary Southeast Asia. It seeks to understand the macro social and political processes, and provides an analysis of how social, political, and cultural factors influence the opportunities and constraints to more equitable, inclusive development. Th...

  17. A failure modes, mechanisms, and effects analysis (FMMEA) of lithium-ion batteries

    Science.gov (United States)

    Hendricks, Christopher; Williard, Nick; Mathew, Sony; Pecht, Michael

    2015-11-01

    Lithium-ion batteries are popular energy storage devices for a wide variety of applications. As batteries have transitioned from being used in portable electronics to being used in longer lifetime and more safety-critical applications, such as electric vehicles (EVs) and aircraft, the cost of failure has become more significant both in terms of liability as well as the cost of replacement. Failure modes, mechanisms, and effects analysis (FMMEA) provides a rigorous framework to define the ways in which lithium-ion batteries can fail, how failures can be detected, what processes cause the failures, and how to model failures for failure prediction. This enables a physics-of-failure (PoF) approach to battery life prediction that takes into account life cycle conditions, multiple failure mechanisms, and their effects on battery health and safety. This paper presents an FMMEA of battery failure and describes how this process enables improved battery failure mitigation control strategies.

  18. Analysis of Variance with Summary Statistics in Microsoft® Excel®

    Science.gov (United States)

    Larson, David A.; Hsu, Ko-Cheng

    2010-01-01

    Students regularly are asked to solve Single Factor Analysis of Variance problems given only the sample summary statistics (number of observations per category, category means, and corresponding category standard deviations). Most undergraduate students today use Excel for data analysis of this type. However, Excel, like all other statistical…

  19. Controllability Analysis for Multirotor Helicopter Rotor Degradation and Failure

    Science.gov (United States)

    Du, Guang-Xun; Quan, Quan; Yang, Binxian; Cai, Kai-Yuan

    2015-05-01

    This paper considers the controllability analysis problem for a class of multirotor systems subject to rotor failure/wear. It is shown that classical controllability theories of linear systems are not sufficient to test the controllability of the considered multirotors. Owing to this, an easy-to-use measurement index is introduced to assess the available control authority. Based on it, a new necessary and sufficient condition for the controllability of multirotors is derived. Furthermore, a controllability test procedure is approached. The proposed controllability test method is applied to a class of hexacopters with different rotor configurations and different rotor efficiency parameters to show its effectiveness. The analysis results show that hexacopters with different rotor configurations have different fault-tolerant capabilities. It is therefore necessary to test the controllability of the multirotors before any fault-tolerant control strategies are employed.

  20. Radiology failure mode and effect analysis: what is it?

    Science.gov (United States)

    Abujudeh, Hani H; Kaewlai, Rathachai

    2009-08-01

    Proactive prevention of medical errors is critical in medical practice. Root cause analysis (RCA) is a conventional method used to deal with errors that result in an adverse event. However, RCA has several limitations. An analytic method for health care risk management, health care failure mode and effect analysis (FMEA), has been introduced relatively recently. Health care FMEA combines several existing analytic approaches into one simple tool with which to analyze a particular health care process, determine the risks associated with it, and develop corrective actions and outcome measures. The authors provide a brief history of health care FMEA, describe its validation process, and relate their experience with its use in a radiology department.

  1. Tool Failure Analysis in High Speed Milling of Titanium Alloys

    Institute of Scientific and Technical Information of China (English)

    ZHAO Xiuxu; MEYER Kevin; HE Rui; YU Cindy; NI Jun

    2006-01-01

    In high speed milling of titanium alloys the high rate of tool failure is the main reason for its high manufacturing cost. In this study, fractured tools which were used in a titanium alloys 5-axis milling process have been observed both in the macro scale using a PG-1000 light microscope and in the micro scale using a Scanning Electron Microscope (SEM) respectively. These observations indicate that most of these tool fractures are the result of tool chipping. Further analysis of each chipping event has shown that beachmarks emanate from points on the cutting edge. This visual evidence indicates that the cutting edge is failing in fatigue due to cyclical mechanical and/or thermal stresses. Initial analyses explaining some of the outlying conditions for this phenomenon are discussed. Future analysis regarding determining the underlying causes of the fatigue phenomenon is then outlined.

  2. 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

  3. Discourse Analysis and Language Learning [Summary of a Symposium].

    Science.gov (United States)

    Hatch, Evelyn

    1981-01-01

    A symposium on discourse analysis and language learning is summarized. Discourse analysis can be divided into six fields of research: syntax, the amount of syntactic organization required for different types of discourse, large speech events, intra-sentential cohesion in text, speech acts, and unequal power discourse. Research on speech events and…

  4. Discourse Analysis and Language Learning [Summary of a Symposium].

    Science.gov (United States)

    Hatch, Evelyn

    1981-01-01

    A symposium on discourse analysis and language learning is summarized. Discourse analysis can be divided into six fields of research: syntax, the amount of syntactic organization required for different types of discourse, large speech events, intra-sentential cohesion in text, speech acts, and unequal power discourse. Research on speech events and…

  5. 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...

  6. Failure analysis of a kind of low power connector

    Institute of Scientific and Technical Information of China (English)

    ZHOU Yi-lin; ZENG Ning; XU Liang-jun; J(O)RGENS Stefan

    2007-01-01

    A kind of low power connector used e.g. in household appliances was partly burned in routine experiment. The heat sources were four paralleled contacts constructed by springs (Sn/CuSn-alloy) in socket and a plug sheet (Ni/Steel) while mating. The contact interfaces were detected by scanning electronic microscope (SEM) and X-ray energy dispersive spectroscopy (XEDS), obvious wear tracks and various contaminants, including element Si, Al, Na, K, S, C1, O, etc., were found. The contamination degrees on the four paralleled contacts .were different, so that the ratio of average contact resistance on the four contacts was about 5:8:3:1. The maximum contact resistance on contacts of the plug sheet reached 28 Ω. The main failure reasons were fretting and contamination between the contact interfaces. Fretting simulation showed that connection resistance of connectors was raised up, even to ohms level. When the current increased to 5 A, the socket housing was heated and decomposed. By the thermal analysis, it was estimated that the connector would be burned under the lower current if the current was not evenly distributed on the four paralleled contacts caused by uneven contamination. Improvement methods for connector failure are also discussed.

  7. Failure Analysis in Steam Generators: A Study Case

    Directory of Open Access Journals (Sweden)

    Alberto Eduardo Calvo González

    2016-04-01

    Full Text Available The use of crude oil as alternative to fuel steam power stations was justifi ed by economic reasons. Thischange of fuel required to modify the operational procedures, due fundamentally to its lower heating valueand its high density and viscosity. Nevertheless the changes made, the use of the crude oil caused aquick deterioration of the thermal exchange surfaces causing not planned forced outages. The statisticalanalysis of the steam generator forced outages went to reheater number two. Therefore the scope of thiswork is the study of the happened failures in reheater number two, of 433,536 kg/hr, 13,4 MPa, and 525 Ctemperature of superheated and reheated steam generator used to move 125 MW turbines. In the carriedout failure analysis, based on nondestructive evaluation methods, towered with metallographic test, waspossible to clarify the root cause, as well as establish the worsening growth rate that allowed establishingthe sequence of tests to avoid a possible not planned outage. In turn it was possible to choose the kind ofsteel should be used in that reheater to give the defi nitive solution of the problem. While steel substitutionis not carried out it sho uld stay the régime of tests and proposed assays. This experience can serve frombase to the design of a maintenance system based on the condition.

  8. Spatial Stratification of Order As Used in Failure Analysis

    Science.gov (United States)

    Leonard, Robert H.; Bachlechner, Martina E.

    2007-03-01

    Silicon nitride deposited on silicon substrates has application in dielectric layers for microelectronics as well as in photovoltaics. During production and operation of components involving silicon/silicon nitride interfaces, stresses and strains can build up at various temperatures resulting in component failure. Using molecular dynamics simulations the influence of temperature and rate of externally applied strain on silicon/silicon nitride interfaces has been analyzed. The primary purpose of this research is to understand the mechanisms leading to the failure of these films. Analyses involving bond lengths and angles have been developed to gain insight into these mechanisms. Methods for stratifying bond lengths and bond angles into unique sub-populations on the basis of spatial orientation have been developed, and have given much insight to how the material behaves, particularly with regards to the Poisson effect. Possible extensions of this stratification method to primitive rings will also be examined. In combination with experimental observations, this analysis will deepen our understanding of the structural properties of silicon/silicon nitride interfaces.

  9. A 3D Analysis of Rock Block Deformation and Failure Mechanics Using Terrestrial Laser Scanning

    Science.gov (United States)

    Rowe, Emily; Hutchinson, D. Jean; Kromer, Ryan A.; Edwards, Tom

    2017-04-01

    Many natural geological hazards are present along the Thompson River corridor in British Columbia, Canada, including one particularly hazardous rocky slope known as the White Canyon. Railway tracks used by Canadian National (CN) and Canadian Pacific (CP) Railway companies pass through this area at the base of the Canyon slope. The geologically complex and weathered rock face exposed at White Canyon is prone to rockfalls. With a limited ditch capacity, these falling rocks have the potential to land on the tracks and therefore increase the risk of train derailment. Since 2012, terrestrial laser scanning (TLS) data has been collected at this site on a regular basis to enable researchers at Queen's University to study these rockfalls in greater detail. In this paper, the authors present a summary of an analysis of these TLS datasets including an examination of the pre-failure deformation patterns exhibited by failed rock blocks as well as an investigation into the influence of structural constraints on the pre-failure behavior of these blocks. Aligning rockfall source zones in an early point cloud dataset to a later dataset generates a transformation matrix describing the movement of the block from one scan to the next. This process was repeated such that the motion of the block over the entire TLS data coverage period was measured. A 3D roto-translation algorithm was then used to resolve the motion into translation and rotation components (Oppikofer et al. 2009; Kromer et al. 2015). Structural information was plotted on a stereonet for further analysis. A total of 111 rockfall events exceeding a volume of 1 m3 were analyzed using this approach. The study reveals that although some rockfall source blocks blocks do not exhibit detectable levels of deformation prior to failure, others do experience cm-level translation and rotation on the order of 1 to 6 degrees before detaching from the slope. Moreover, these movements may, in some cases, be related to the discontinuity

  10. Summary of NGNP Engineering Analysis Progress in Fiscal Year 2010

    Energy Technology Data Exchange (ETDEWEB)

    Phillip M. Mills

    2010-09-01

    The Engineering Analysis work package accomplished a number of activities in FY2010 that will help to inform Licensing, R&D, and detailed design activities that will be performed during the preliminary design phase in Phase 2 of the NGNP Project. These activities were in the following areas: • Fission Product Transport • DDN Update and Consolidation • Gas Reactor Lessons Learned Review • Reactor Coolant Chemistry Control • Resilient Control Systems for High Temperature Gas-cooled Reactors • Water-ingress Analysis In total, the efforts associated with the Engineering Analysis work package accomplished four (4) Level 2 milestones and two (2) internal (Level 4) milestones. Details of the activities and milestones are included in the attached report.

  11. Photovoltaic venture analysis. Final report. Volume I. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    Costello, D.; Posner, D.; Schiffel, D.; Doane, J.; Bishop, C.

    1978-07-01

    The objective of the study, government programs under investigation, and a brief review of the approach are presented. Potential markets for photovoltaic systems relevant to the study are described. The response of the photovoltaic supply industry is then considered. A model which integrates the supply and demand characteristics of photovoltaics over time was developed. This model also calculates the economic benefits associated with various government subsidy programs. Results are derived under alternative possible supply, demand, and macroeconomic conditions. A probabilistic analysis of the costs and benefits of a $380 million federal photovoltaic procurement initiative, as well as certain alternative strategies, is summarized. Conclusions and recommendations based on the analysis are presented.

  12. Summary of fracture mechanics problems analysis method in ABAQUS

    Directory of Open Access Journals (Sweden)

    Duan Hongjun

    2015-07-01

    Full Text Available Fracture mechanics is the study of the strength of the materials or structures with crack and crack propagation regularity of a discipline. There are a lot of analysis function of ABAQUS, including fracture analysis. ABAQUS is very easy to use and easy to establish a model of the complicated problem. In order to effectively study of strong discontinuity problems such as crack, provides two methods of simulating the problem of cracks of ABAQUS. This paper describes the two methods respectively, and compare two methods.

  13. Comprehensive failure analysis of leakage faults in bipolar transistors

    Science.gov (United States)

    Domengès, B.; Murray, H.; Schwindenhammer, P.; Imbert, G.

    2004-02-01

    The origin of a leakage current in several failed NPN bipolar transistors has been identified by complementary advanced failure analysis techniques. After precise localization of the failing area by photon emission microscopy and optical beam induced resistance change investigations, a focus ion beam technique was used to prepare thin lamellae adequate for transmission electron microscopy (TEM) study. Characterization of the related microstructure was performed by TEM and energy-dispersive spectrometry nanobeam analyses. It was identified as Ti-W containing trickle-like residue located at the surface of the spacers. Current-voltage measurements could be related to such structure defects and the involved conduction mechanism was identified as the Poole-Frenkel effect.

  14. Failure analysis of the fractured wires in sternal perichronal loops.

    Science.gov (United States)

    Chao, Jesús; Voces, Roberto; Peña, Carmen

    2011-10-01

    We report failure analysis of sternal wires in two cases in which a perichronal fixation technique was used to close the sternotomy. Various characteristics of the retrieved wires were compared to those of unused wires of the same grade and same manufacturer and with surgical wire specifications. In both cases, wire fracture was un-branched and transgranular and proceeded by a high cycle fatigue process, apparently in the absence of corrosion. However, stress anlysis indicates that the effective stress produced during strong coughing is lower than the yield strength. Our findings suggest that in order to reduce the risk for sternal dehiscence, the diameter of the wire used should be increased. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Corrosion failure analysis of hearing aid battery-spring contacts

    DEFF Research Database (Denmark)

    Gudla, Visweswara Chakravarthy; Ambat, Rajan

    2017-01-01

    Reliability of low power electrical contacts such as those in hearing aid battery-spring systems is a very critical aspect for the overall performance of the device. These systems are exposed to certain harsh environments like high humidity and elevated temperatures, and often in combination...... with high levels of salt from human perspiration and environmental pollutants. In addition, the design aspects of such systems often call for multi-material combinations of substrate and coatings for catering to various requirements such as electrical conductivity and wear resistance, which in turn enhance...... the susceptibility of these systems to galvanic corrosion. In this study, traditional behind the ear (BTE) hearing aid systems, which failed during service were analysed. Failure analysis was performed on the dome type battery-spring contact systems. The morphology of the contact areas was observed using scanning...

  16. Cote d'Ivoire - Country Environmental Analysis : Executive Summary

    OpenAIRE

    World Bank

    2010-01-01

    The purpose of this country environmental analysis (CEA) is to assist the Government of Cote d'Ivoire, development partners and civil society to integrate environmental issues into policy dialogues and country programming through: a) assessing environmental priorities in Cote d'Ivoire, b) identifying environmental implications of key policies, c) evaluating the country's institutional capa...

  17. Analysis of Service Recovery Failure: From Minority Perspective

    Directory of Open Access Journals (Sweden)

    Yasemin Öcal Atınç

    2016-10-01

    Full Text Available We investigate the service failures towards diverse customer groups for the purpose to bring insightful proposals to the managers to recover from these failures. Previous literature provided insights regarding the perception of service failures by minorities and the challenge of recovery due to racial implications driven from the failure, however lacked to propose suggestions for the managers so that they can take either corrective steps toward service failure recovery or prevent service failure through an effective training program. In this conceptual paper, we propose that, when the service provider and the customer are from different races, and the customer experiences a service failure, without the understanding of the process, service recovery is very hard to achieve. Race is an important factor in intention to bring the customer back for repurchase. The main contribution of this research is adding the race factor and the understanding of the service process into the model.

  18. Business Case Analysis of Prototype Fabrication Division Recapitalization Plan. Summary

    Energy Technology Data Exchange (ETDEWEB)

    Booth, Steven Richard [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Benson, Faith Ann [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dinehart, Timothy Grant [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-04-30

    Business case studies were completed to support procurement of new machines and capital equipment in the Prototype Fabrication (PF) Division SM-39 and TA-03-0102 machine shops. Economic analysis was conducted for replacing the Mazak 30Y Mill-Turn Machine in SM-39, the Haas Vertical CNC Mill in Building 102, and the Hardinge Q10/65-SP Lathe in SM-39. Analysis was also conducted for adding a NanoTech Lathe in Building 102 and a new electrical discharge machine (EDM) in SM-39 to augment current capabilities. To determine the value of switching machinery, a baseline scenario was compared with a future scenario where new machinery was purchased and installed. Costs and benefits were defined via interviews with subject matter experts.

  19. The Reconstruction and Failure Analysis of The Space Shuttle Columbia

    Science.gov (United States)

    Russell, Richard W.

    2010-01-01

    This viewgraph presentation describes a very detailed reconstruction plan and failure analysis of The Space Shuttle Columbia accident. The contents include: 1) STS-107 Timeline; 2) Foam Impact; 3) Recovery; 4) Reconstruction; 5) Reconstruction Plan; 6) Reconstruction Hanger; 7) Pathfinders; 8) Aluminum Pathfinder; 9) Early Analysis - Left MLG Door Area; 10) Emphasis Switched to Left Hand Wing Leading Edge; 11) Wing Leading Edge Subsystem (LESS); 12) 3D Reconstruction of Left WLE; 13) Left Wing Tile Table; 14) LESS Observations; 15) Left Hand Wing Debris Points to RCC 8/9 - Slumped Tile; 16) Reconstructed View of LC/P 9 tile with I/B Tile; 17) Reconstructed View of Lower C/P 9 Tile; 18) Carrier Panel 8 - Upper; 19) Left Hand Wing Debris Points to RCC 8/9 - Erosion and RCC with attach hole intact; 20) Erosion on Panel 8 Upper Outboard Rib; 21) RCC Panels 8 & 9 Erosion Features; 22) Slumping Source for Carrier Panel 9 Tile was Revealed; 23) Debris Indicated Highest Probability Initiation Site; 24) Left Hand Wing Debris Points to RCC 8/9- Metallic Deposits; 25) Relative Metallic Deposition on L/H Wing Materials; 26) Metallic Deposit Example, LH RCC 8; 27) High Level Questions; 28) Analysis Plan Challenges; 29) Analysis Techniques; 30) Analysis Approach; 31) RCC Panel 8 Erosion Features; 32) Radiographic Features; 33) Radiography WLE LH Panel 8; 34) LH RCC 8 Upper Apex; 35) LH RCC 8 - Deposit Feature: Thick Tear Shaped; 36) LH RCC 8 - Deposit Feature: Thick Globules; 37) LH RCC 8 - Deposit Feature: Spheroids; 38) LH RCC 8 - Deposit Feature: Uniform Deposit; 39) Significant Findings - Sampling All Other panels; 40) Proposed Breach Location and Plasma Flow; 41) Corroborating Information - RCC Panel Debris Locations; 42) Corroborating Information - LH OMS Pod Analysis; 43) Corroborating Information - Impact Testing; and 44) Overall Forensic Conclusions.

  20. Tool to estimate optical metrics from summary wave-front analysis data in the human eye

    NARCIS (Netherlands)

    Jansonius, Nomdo M.

    2013-01-01

    Purpose Studies in the field of cataract and refractive surgery often report only summary wave-front analysis data data that are too condensed to allow for a retrospective calculation of metrics relevant to visual perception. The aim of this study was to develop a tool that can be used to estimate t

  1. Army Training Study: Training Effectiveness Analysis (TEA) Summary.

    Science.gov (United States)

    1978-08-08

    la In parallel with step 1 develop by analysis a list of areas in which learning is expected to occur by playing BATTLE. lb Take union of step 1 and...development of team proficiency and espirit , both of which are essential to Improve the generally unsatisfactory performance of the test sample. A 1 L’- "A...III model conducted using the mid-1980 European scenario modified for the study based upon the RED air raid expected over a division size ground force

  2. Liver support therapy with molecular adsorbents recirculating system in liver failure:a summary of 252 cases from 14 centers in China

    Institute of Scientific and Technical Information of China (English)

    WANG Min-min; HU Xiao-bin; LUO Hong-tao; LIU Yi-he; WANG Wen-ya; CHEN Shi-jun; YE Qi-fa; YANG Yi-jun; CHEN Shi-bin; ZHOU Xin-min; GUO Li-min; ZHANG Yue-xin; DING Xiao-qiang

    2008-01-01

    Background A liver support therapy,named molecular adsorbents recirculating system (MARS),has been used for more than 700 liver failure patients in China.We made here a summary to evaluate the effects of MARS treatment in different applications with emphasis on hepatitis B virus (HBV) based liver failure.Methods This report analyzed data of 252 patients (mean age (44.9±12.7) years) in three groups:acute severe hepatitis (ASH),subacute severe hepatitis (SSH) and chronic severe hepatitis (CSH).The largest group was CSH (156 patients,61.9%),and 188 patients (74.6%,188/252) were infected with HBV.Results MARS treatments were associated with significant reduction of albumin bound toxins and water-soluble toxins.Most of the patients showed a positive response with a significant improvement of multiple organ function substantiated by a significant increase in prothrombin time activity (PTA) and median arterial pressure (MAP).There was a decrease in hepatic encephalopathy (HE) grade and Child-Turcotte-Pugh (CTP) scale.Thirty-nine of 188 HBV patients (20.7%) dropped out of the commendatory consecutive therapy ending with lower survival of 43.6% while the rest of the 149 patients had a survival rate of 62.4%.Survival within the ASH and SSH groups were 81.2% and 75.0%,respectively.In the CSH group,end stage patients were predominant (65/151,43%),whereas the early and middle stage patients had a better prognosis:early stage survival,including orthotopic liver transplantation (OLT) survival of 91.7%,middle stage survival of 75%,end stage survival of 33.8%.Conclusions MARS continues to be the most favorable extracorporeal treatment for liver support therapy in China for a wide range of conditions,including the majority of hepatitis B related liver failure conditions.The appropriate application of MARS for the right indications and stage of hepatic failure,as well as the fulfillment of prescribed treatments,will lead to the optimal therapeutic result.

  3. Analysis of information systems for hydropower operations: Executive summary

    Science.gov (United States)

    Sohn, R. L.; Becker, L.; Estes, J.; Simonett, D.; Yeh, W.

    1976-01-01

    An analysis was performed of the operations of hydropower systems, with emphasis on water resource management, to determine how aerospace derived information system technologies can effectively increase energy output. Better utilization of water resources was sought through improved reservoir inflow forecasting based on use of hydrometeorologic information systems with new or improved sensors, satellite data relay systems, and use of advanced scheduling techniques for water release. Specific mechanisms for increased energy output were determined, principally the use of more timely and accurate short term (0-7 days) inflow information to reduce spillage caused by unanticipated dynamic high inflow events. The hydrometeorologic models used in predicting inflows were examined in detail to determine the sensitivity of inflow prediction accuracy to the many variables employed in the models, and the results were used to establish information system requirements. Sensor and data handling system capabilities were reviewed and compared to the requirements, and an improved information system concept was outlined.

  4. City of Hoboken Energy Surety Analysis: Preliminary Design Summary

    Energy Technology Data Exchange (ETDEWEB)

    Stamp, Jason Edwin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Military and Energy Systems Analysis Dept.; Baca, Michael J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Military and Energy Systems Analysis Dept.; Munoz-Ramos, Karina [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Military and Energy Systems Analysis Dept.; Schenkman, Benjamin L. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Military and Energy Systems Analysis Dept.; Eddy, John P. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Systems Readiness and Sustainment Technology Dept.; Smith, Mark A. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Systems Readiness and Sustainment Technology Dept.; Guttromson, Ross [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Electric Power Systems Research Dept.; Henry, Jordan M. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Critical Infrastructure Systems Dept.; Jensen, Richard Pearson [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States). Geomechanics Dept.

    2014-09-01

    In 2012, Hurricane Sandy devastated much of the U.S. northeast coastal areas. Among those hardest hit was the small community of Hoboken, New Jersey, located on the banks of the Hudson River across from Manhattan. This report describes a city-wide electrical infrastructure design that uses microgrids and other infrastructure to ensure the city retains functionality should such an event occur in the future. The designs ensure that up to 55 critical buildings will retain power during blackout or flooded conditions and include analysis for microgrid architectures, performance parameters, system control, renewable energy integration, and financial opportunities (while grid connected). The results presented here are not binding and are subject to change based on input from the Hoboken stakeholders, the integrator selected to manage and implement the microgrid, or other subject matter experts during the detailed (final) phase of the design effort.

  5. Physicochemical characterization and failure analysis of military coating systems

    Science.gov (United States)

    Keene, Lionel Thomas

    Modern military coating systems, as fielded by all branches of the U.S. military, generally consist of a diverse array of organic and inorganic components that can complicate their physicochemical analysis. These coating systems consist of VOC-solvent/waterborne automotive grade polyurethane matrix containing a variety of inorganic pigments and flattening agents. The research presented here was designed to overcome the practical difficulties regarding the study of such systems through the combined application of several cross-disciplinary techniques, including vibrational spectroscopy, electron microscopy, microtomy, ultra-fast laser ablation and optical interferometry. The goal of this research has been to determine the degree and spatial progression of weathering-induced alteration of military coating systems as a whole, as well as to determine the failure modes involved, and characterizing the impact of these failures on the physical barrier performance of the coatings. Transmission-mode Fourier Transform Infrared (FTIR) spectroscopy has been applied to cross-sections of both baseline and artificially weathered samples to elucidate weathering-induced spatial gradients to the baseline chemistry of the coatings. A large discrepancy in physical durability (as indicated by the spatial progression of these gradients) has been found between older and newer generation coatings. Data will be shown implicating silica fillers (previously considered inert) as the probable cause for this behavioral divergence. A case study is presented wherein the application of the aforementioned FTIR technique fails to predict the durability of the coating system as a whole. The exploitation of the ultra-fast optical phenomenon of femtosecond (10-15S) laser ablation is studied as a potential tool to facilitate spectroscopic depth profiling of composite materials. Finally, the interferometric technique of Phase Shifting was evaluated as a potential high-sensitivity technique applied to the

  6. [Failure mode and effects analysis on computerized drug prescriptions].

    Science.gov (United States)

    Paredes-Atenciano, J A; Roldán-Aviña, J P; González-García, Mercedes; Blanco-Sánchez, M C; Pinto-Melero, M A; Pérez-Ramírez, C; Calvo Rubio-Burgos, Miguel; Osuna-Navarro, F J; Jurado-Carmona, A M

    2015-01-01

    To identify and analyze errors in drug prescriptions of patients treated in a "high resolution" hospital by applying a Failure mode and effects analysis (FMEA).Material and methods A multidisciplinary group of medical specialties and nursing analyzed medical records where drug prescriptions were held in free text format. An FMEA was developed in which the risk priority index (RPI) was obtained from a cross-sectional observational study using an audit of the medical records, carried out in 2 phases: 1) Pre-intervention testing, and (2) evaluation of improvement actions after the first analysis. An audit sample size of 679 medical records from a total of 2,096 patients was calculated using stratified sampling and random selection of clinical events. Prescription errors decreased by 22.2% in the second phase. FMEA showed a greater RPI in "unspecified route of administration" and "dosage unspecified", with no significant decreases observed in the second phase, although it did detect, "incorrect dosing time", "contraindication due to drug allergy", "wrong patient" or "duplicate prescription", which resulted in the improvement of prescriptions. Drug prescription errors have been identified and analyzed by FMEA methodology, improving the clinical safety of these prescriptions. This tool allows updates of electronic prescribing to be monitored. To avoid such errors would require the mandatory completion of all sections of a prescription. Copyright © 2014 SECA. Published by Elsevier Espana. All rights reserved.

  7. Probabilistic Failure Analysis for Wound Composite Ceramic Cladding Assembly

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James Gordon [ORNL; Lara-Curzio, Edgar [ORNL

    2013-01-01

    Advanced ceramic matrix composites based on silicon carbide (SiC) are being considered as candidate material systems for nuclear fuel cladding in light water reactors. The SiC composite structure is considered due to its assumed exceptional performance under accident scenarios, where its excellent high-temperature strength and slow reaction kinetics with steam and associated mitigated hydrogen production are desirable. The specific structures of interest consist of a monolithic SiC cylinder surrounded by interphase-coated SiC woven fibers in a tubular form and infiltrated with SiC. Additional SiC coatings on the outermost surface of the assembly are also being considered to prevent hydrothermal corrosion of the fibrous structure. The inner monolithic cylinder is expected to provide a hermetic seal to contain fission products under normal conditions. While this approach offers the promise of higher burn-up rates and safer behavior in the case of LOCA events, the reliability of such structures must be demonstrated in advance. Therefore, a probability failure analysis study was performed of such monolithic-composite hybrid structures to determine the feasibility of these design concepts. This analysis will be used to predict the future performance of candidate systems in an effort to determine the feasibility of these design concepts and to make future recommendations regarding materials selection.

  8. Women's Experiences With Flap Failure After Autologous Breast Reconstruction: A Qualitative Analysis.

    Science.gov (United States)

    Higgins, Kristen S; Gillis, Joshua; Williams, Jason G; LeBlanc, Martin; Bezuhly, Michael; Chorney, Jill M

    2016-10-06

    Clinical experience suggests that flap failure after autologous breast reconstruction can be a devastating experience for women. Previous research has examined women's experiences with autologous breast reconstruction with and without complications, and patients' experiences with suboptimal outcomes from other medical procedures. The authors aimed to examine the psychosocial experience of flap failure from the patient's perspective. Seven women who had experienced unilateral flap failure after deep inferior epigastric perforator flap surgery in the past 12 years completed semistructured interviews about their breast cancer treatments, their experiences with flap failure, the impact of flap failure on their lives, and the coping strategies they used. Interpretive phenomenological analysis, a type of qualitative analysis that provides an in-depth account of participant's experiences and their meanings, was used to analyze the interview data. From these data, patient-derived recommendations were developed for surgeons caring for women who have experienced flap failure. Three main themes (6 subthemes) emerged: coming to terms with flap failure (coping with emotions, body dissatisfaction); making meaning of flap failure experience (questioning, relationship with surgeon); and care providers acknowledging the emotional experience of flap failure (experience of being treated "mechanically," suggestions for improvement). In conclusion, flap failure in breast reconstruction is an emotionally difficult experience for women. Although there are similarities to other populations of patients experiencing suboptimal outcomes from medical procedures, there are also unique aspects of the flap failure experience. A better understanding of women's experiences with flap failure will assist in providing more appropriate supports.

  9. ANALYSIS OF FAILURE MECHANISM IN MULTIPLE DISC WET BRAKES

    Institute of Scientific and Technical Information of China (English)

    1998-01-01

    By the numberical calculation of dynamic lining pressure distributions,temperature fields and thermal stress fields of steel plates,a method using nonlinear finite element techniques to analyze failure mechanism of a multiple disc wet brake is detailed ,and some measures for combatting these failures are provided.

  10. Identifying failure mechanisms in LDMOS transistors by analytical stability analysis

    NARCIS (Netherlands)

    Ferrara, A.; Steeneken, P.G.; Boksteen, B.K.; Heringa, A.; Scholten, A.J.; Schmitz, J.; Hueting, R.J.E.

    2014-01-01

    In this work, analytical stability equations are derived and combined with a physics-based model of an LDMOS transistor in order to identify the primary cause of failure in different operating and bias conditions. It is found that there is a gradual boundary between an electrical failure region at h

  11. Metallized Film Capacitor Lifetime Evaluation and Failure Mode Analysis

    CERN Document Server

    Gallay, R

    2015-01-01

    One of the main concerns for power electronic engineers regarding capacitors is to predict their remaining lifetime in order to anticipate costly failures or system unavailability. This may be achieved using a Weibull statistical law combined with acceleration factors for the temperature, the voltage, and the humidity. This paper discusses the different capacitor failure modes and their effects and consequences.

  12. Cascading failure analysis and restoration strategy in an interdependent network

    Science.gov (United States)

    Hong, Sheng; Lv, Chuan; Zhao, Tingdi; Wang, Baoqing; Wang, Jianghui; Zhu, Juxing

    2016-05-01

    In modern society, many infrastructures are interdependent owing to functional and logical relations among components in different systems. These networked infrastructures can be modeled as interdependent networks. In the real world, different networks carry different traffic loads whose values are dynamic and stem from the load redistribution in the same network and disturbance from the interdependent network. Interdependency makes interdependent networks so fragile that even a slight initial disturbance may lead to a cascading failure of the entire systems. In this paper, interdependencies among networks are modeled and a failure cascade process is studied considering their effects on failure propagation. Meanwhile, an in-process restoration strategy after the initial failure is investigated. The restoration effects depend strongly on the trigger timing, restoration probability and priority of the restoration actions along with the additional disturbances. Our findings highlight the necessity to decrease the large-scale cascading failure by structuring and managing an interdependent network reasonably.

  13. Effects of exercise training on maximal oxygen uptake in heart failure : a systematic review and meta-analysis

    OpenAIRE

    Kaski, Hanna

    2012-01-01

    SUMMARY Aims. Low cardiorespiratory fitness is a common physical status among patients with heart failure. Several studies have examined the effects of exercise training on maximal oxygen uptake (VO2max) in heart failure. Though, these studies had relatively small sample sizes and highly variable results. Therefore the aim of this study was to systemically review the effects of exercise training on VO2max in heart failure patients. Methods. Database search of randomized controlled t...

  14. Lifetime prediction and failure analysis of organic coatings by EIS

    Institute of Scientific and Technical Information of China (English)

    YAN Rui; WU Hang; MA Shi-ning; XU Bin-shi

    2004-01-01

    Organic coatings are widely used to control the corrosion of steel structure. The anticorrosive property of these coatings depends on their barrier properties, making a separation between the corrosive medium and the substrate. But unavoidable completely small pores, cracks and other defects in organic coatings may cause ions, water, gases, and other corrosive species penetrate and distribute in the coatings, causing accumulation and swelling of coatings, so leading to the degradation of coatings. In addition, water affects the permeation of oxygen and other corrosive medium, consequently the presence of such substances at coating-metal interface promotes corrosion of metal substrate. So the absorbability of the coatings to water may be one of the most important factors in undercoating corrosion. In recent years, electrochemical impedance spectroscopy (EIS) has been established and frequently used as a non-destructive testing method for assessing the performance of organic coatings, especially for the determination of the water content in organic coatings, since the capacitance of the coatings is sensitive to the penetration of water. So from EIS it can extract a wealth of information on the electrochemical corrosion of coated steels, especially, it can be utilized to assess organic coatings used under particular surroundings. The principle, methods and application of EIS on evaluating life-span and analyzing failure mechanism of organic coatings are also introduced briefly. Combining other analysis techniques such as XRD, SEM and FTIR with electrochemical technique, it will blaze a way in studying degradation mechanism of organic coatings and estimating their lifetime.

  15. Going South: Analysis of an Historic Project Engineering Failure

    Science.gov (United States)

    Scott, John H.

    2009-01-01

    NASA's successful conduct of the Apollo Program greatly enhanced the prestige of the United States and remains broadly accepted as America's gift to all Mankind. NASA's accomplishments continue to amaze the world. With the Vision for Space Exploration (VSE) Americans once again tasked NASA to carry out a project that is expected to provide inspiration and economic stimulus to the United States and to the world. In preparation NASA has thoroughly examined space program precedents. There is, however, another precedent which has not been examined in this context but whose scope and environment in many ways parallel the VSE. This project was initiated by a team that had, ten years before, successfully completed an effort that, at a cost of $173 billion (in 2008 dollars), had pushed the envelope of technology, brought economic growth, established their country as the world leader in engineering, and been broadly accepted as that country's gift to all Mankind. The new project was again inspired by popular desire to enhance national prestige and make yet another major contribution to Humanity. This effort was predicted to require eight years and $156 billion (2008 dollars). However, after nine years and expenditures of 96% beyond the baseline, the project collapsed amid bankruptcy, political scandal, and criminal prosecution. This paper applies current project management metrics, such as earned value analysis, to review the strategic decisions in this historic failure and describe its ultimate collapse. Key mistakes are identified, and lessons are drawn which may prove useful in guiding the VSE.

  16. Probabilistic analysis of cascade failure dynamics in complex network

    Science.gov (United States)

    Zhang, Ding-Xue; Zhao, Dan; Guan, Zhi-Hong; Wu, Yonghong; Chi, Ming; Zheng, Gui-Lin

    2016-11-01

    The impact of initial load and tolerance parameter distribution on cascade failure is investigated. By using mean field theory, a probabilistic cascade failure model is established. Based on the model, the damage caused by certain attack size can be predicted, and the critical attack size is derived by the condition of cascade failure end, which ensures no collapse. The critical attack size is larger than the case of constant tolerance parameter for network of random distribution. Comparing three typical distributions, simulation results indicate that the network whose initial load and tolerance parameter both follow Weibull distribution performs better than others.

  17. Fractographic ceramic failure analysis using the replica technique

    Science.gov (United States)

    Scherrer, Susanne S.; Quinn, Janet B.; Quinn, George D.; Anselm Wiskott, H. W.

    2007-01-01

    Objectives To demonstrate the effectiveness of in vivo replicas of fractured ceramic surfaces for descriptive fractography as applied to the analysis of clinical failures. Methods The fracture surface topography of partially failed veneering ceramic of a Procera Alumina molar and an In Ceram Zirconia premolar were examined utilizing gold-coated epoxy poured replicas viewed using scanning electron microscopy. The replicas were inspected for fractographic features such as hackle, wake hackle, twist hackle, compression curl and arrest lines for determination of the direction of crack propagation and location of the origin. Results For both veneering ceramics, replicas provided an excellent reproduction of the fractured surfaces. Fine details including all characteristic fracture features produced by the interaction of the advancing crack with the material's microstructure could be recognized. The observed features are indicators of the local direction of crack propagation and were used to trace the crack's progression back to its initial starting zone (the origin). Drawbacks of replicas such as artifacts (air bubbles) or imperfections resulting from inadequate epoxy pouring were noted but not critical for the overall analysis of the fractured surfaces. Significance The replica technique proved to be easy to use and allowed an excellent reproduction of failed ceramic surfaces. It should be applied before attempting to remove any failed part remaining in situ as the fracture surface may be damaged during this procedure. These two case studies are intended as an introduction for the clinical researcher in using qualitative (descriptive) fractography as a tool for understanding fracture processes in brittle restorative materials and, secondarily, to draw conclusions as to possible design inadequacies in failed restorations. PMID:17270267

  18. Speed of updating online evidence based point of care summaries: prospective cohort analysis

    Science.gov (United States)

    Cinquini, Michela; Liberati, Alessandro; Moschetti, Ivan; Pecoraro, Valentina; Tagliabue, Ludovica; Moja, Lorenzo

    2011-01-01

    Objective To evaluate the ability of international point of care information summaries to update evidence relevant to medical practice. Design Prospective cohort bibliometric analysis. Setting Top five point of care information summaries (Clinical Evidence, EBMGuidelines, eMedicine, Dynamed, UpToDate) ranked for coverage of medical conditions, editorial quality, and evidence based methodology. Main outcome measures From June 2009 to May 2010 we measured the incidence of research findings relating to potentially eligible newsworthy evidence. As samples, we chose systematic reviews rated as relevant by international research networks (such as, Evidence-Based Medicine, ACP Journal Club, and the Cochrane Collaboration). Every month we assessed whether each sampled review was cited in at least one chapter of the five summaries. The cumulative updating rate was analysed with Kaplan-Meier curves. Results From April to December 2009, 128 reviews were retrieved; 53% (68) from the literature surveillance journals and 47% (60) from the Cochrane Library. At nine months, Dynamed had cited 87% of the sampled reviews, while the other summaries had cited less than 50%. The updating speed of Dynamed clearly led the others. For instance, the hazard ratios for citations in EBM Guidelines and Clinical Evidence versus the top performer were 0.22 (95% confidence interval 0.17 to 0.29) and 0.03 (0.01 to 0.05). Conclusions Point of care information summaries include evidence relevant to practice at different speeds. A qualitative analysis of updating mechanisms is needed to determine whether greater speed corresponds to more appropriate incorporation of new information. PMID:21948588

  19. Prognostic Role of Hypothyroidism in Heart Failure: A Meta-Analysis.

    Science.gov (United States)

    Ning, Ning; Gao, Dengfeng; Triggiani, Vincenzo; Iacoviello, Massimo; Mitchell, Judith E; Ma, Rui; Zhang, Yan; Kou, Huijuan

    2015-07-01

    Hypothyroidism is a risk factor of heart failure (HF) in the general population. However, the relationship between hypothyroidism and clinical outcomes in patients with established HF is still inconclusive.We conducted a systematic review and meta-analysis to clarify the association of hypothyroidism and all-cause mortality as well as cardiac death and/or hospitalization in patients with HF. We searched MEDLINE via PubMed, EMBASE, and Scopus databases for studies of hypothyroidism and clinical outcomes in patients with HF published up to the end of January 2015. Random-effects models were used to estimate summary relative risk (RR) statistics. We included 13 articles that reported RR estimates and 95% confidence intervals (95% CIs) for hypothyroidism with outcomes in patients with HF. For the association of hypothyroidism with all-cause mortality and with cardiac death and/or hospitalization, the pooled RR was 1.44 (95% CI: 1.29-1.61) and 1.37 (95% CI: 1.22-1.55), respectively. However, the association disappeared on adjustment for B-type natriuretic protein level (RR 1.17, 95% CI: 0.90-1.52) and in studies of patients with mean age hypothyroidism associated with increased all-cause mortality as well as cardiac death and/or hospitalization in patients with HF. Further diagnostic and therapeutic procedures for hypothyroidism may be needed for patients with HF.

  20. SRM Internal Flow Test and Computational Fluid Dynamic Analysis. Volume 1; Major Task Summaries

    Science.gov (United States)

    Whitesides, R. Harold; Dill, Richard A.; Purinton, David C.

    1995-01-01

    During the four year period of performance for NASA contract, NASB-39095, ERC has performed a wide variety of tasks to support the design and continued development of new and existing solid rocket motors and the resolution of operational problems associated with existing solid rocket motor's at NASA MSFC. This report summarizes the support provided to NASA MSFC during the contractual period of performance. The report is divided into three main sections. The first section presents summaries for the major tasks performed. These tasks are grouped into three major categories: full scale motor analysis, subscale motor analysis and cold flow analysis. The second section includes summaries describing the computational fluid dynamics (CFD) tasks performed. The third section, the appendices of the report, presents detailed descriptions of the analysis efforts as well as published papers, memoranda and final reports associated with specific tasks. These appendices are referenced in the summaries. The subsection numbers for the three sections correspond to the same topics for direct cross referencing.

  1. Failure mode analysis of a post-tension anchored dam using linear finite element analysis

    Science.gov (United States)

    Corn, Aimee

    There are currently over 84,000 dams in the United States, and the average age of those dams is 52 years. Concrete gravity dams are the second most common dam type, with more than 3,000 in the United States. Current engineering technology and technical understanding of hydrologic and seismic events has resulted in significant increases to the required design loads for most dams; therefore, many older dams do not have adequate safety for extreme loading events. Concrete gravity dams designed and constructed in the early 20th century did not consider uplift pressures beneath the dam, which reduces the effective weight of the structure. One method that has been used to enhance the stability of older concrete gravity dams includes the post-tension anchor (PTA) system. Post-tensioning infers modifying cured concrete and using self-equilibrating elements to increase the weight of the section, which provides added stability. There is a lack of historical evidence regarding the potential failure mechanisms for PTA concrete gravity dams. Of particular interest, is how these systems behave during large seismic events. The objective of this thesis is to develop a method by which the potential failure modes during a seismic event for a PTA dam can be evaluated using the linear elastic finite element method of analysis. The most likely potential failure modes (PFM) for PTA designs are due to tensile failure and shear failure. A numerical model of a hypothetical project was developed to simulate PTAs in the dam. The model was subjected to acceleration time-history motions that simulated the seismic loads. The results were used to evaluate the likelihood of tendon failure due to both tension and shear. The results from the analysis indicated that the PTA load increased during the seismic event; however, the peak load in the tendons was less than the gross ultimate tensile strength (GUTS) and would not be expected to result in tensile failure at the assumed project. The analysis

  2. An Analysis of Pragmatic Failure in Intercultural Communication

    Institute of Scientific and Technical Information of China (English)

    赵要东

    2013-01-01

    With the globalization of the world economy, intercultural communication is becoming more and more important. In China, more and more people learn English,Even though they have little difficulty in understanding the literal meaning of utter⁃ances when confronted with authentic communication situations, they may not interpret the utterances correctly, or express themselves appropriately. The problem of pragmatic failure has been holding an important position in the study of intercultural communication. In this paper I will mainly analyze the phenomena of pragmatic failure in senior middle school students’daily conversations in intercultural communication, and discuss the nature and causes of pragmatic failure in intercultural communica⁃tion situations. After we gain a better understanding of the phenomena, recommendations will be made on how to avoid pragmat⁃ic failure, and to increase intercultural communicative competence in English.

  3. Forensic analysis of asphaltic pavement failures in Ghana: case histories

    CSIR Research Space (South Africa)

    Ampadu, SIK

    2015-08-01

    Full Text Available Many newly constructed asphaltic pavements in Ghana have suffered premature failures shortly after opening to traffic. In all cases, available records from the road agencies appeared to show that the roads were constructed in accordance...

  4. Sample Preservation - The Key to a Successful Failure Analysis

    Science.gov (United States)

    2008-09-01

    carburized tool steel. The outer surface rehardened, transforming into unstable, untempered martensite. The case below this layer was affected...Rehardening and retempering burn in a carburized tool steel subjected to abusive grinding. Litigation: High visibility failures leading to

  5. Failure Analysis of Heavy-Ion-Irradiated Schottky Diodes

    Science.gov (United States)

    Casey, Megan C.; Lauenstein, Jean-Marie; Wilcox, Edward P.; Topper, Alyson D.; Campola, Michael J.; Label, Kenneth A.

    2017-01-01

    In this work, we use high- and low-magnitude optical microscope images, infrared camera images, and scanning electron microscope images to identify and describe the failure locations in heavy-ion-irradiated Schottky diodes.

  6. Analysis of contaminated field failure data for repairable systems

    OpenAIRE

    Hansen, Christian Kornerup; Thyregod, Poul

    1991-01-01

    A simple model for electronic systems with repair, and a method for analyzing recorded field failure data for such systems are presented. The work performed has resulted in analytical results that may be used for assessing the product reliability. The method was originally developed for use under ideal circumstances, but it has been adapted for use with contaminated data (i.e., data where the failure times are observed embedded by noise). A simple model for the noise that enables an analytica...

  7. Failure Analysis and Prevention for the Air Logistics Center Engineer: CAStLE Course Development Summary

    Science.gov (United States)

    2006-09-01

    Strut Lock Basic Mode of Operation 14 - B17 - 7 Failed Assembly USA FA cade/ni LemtLrf for Aircraft. ’trcturaI Life Extension (CASTLE) S•4 in Situ...Building permits "* Massive court case - 3,000 witnesses - 40,000 pages of records - $1M (1925 dollars) paid in damages "* Heightened public and...Large explosion hear immediately after TO - Fire seen from area of right engine - Some witnesses believed right wing separated - G-78T, built in 1947

  8. Modular titanium alloy neck adapter failures in hip replacement - failure mode analysis and influence of implant material

    Directory of Open Access Journals (Sweden)

    Bloemer Wilhelm

    2010-01-01

    Full Text Available Abstract Background Modular neck adapters for hip arthroplasty stems allow the surgeon to modify CCD angle, offset and femoral anteversion intraoperatively. Fretting or crevice corrosion may lead to failure of such a modular device due to high loads or surface contamination inside the modular coupling. Unfortunately we have experienced such a failure of implants and now report our clinical experience with the failures in order to advance orthopaedic material research and joint replacement surgery. The failed neck adapters were implanted between August 2004 and November 2006 a total of about 5000 devices. After this period, the titanium neck adapters were replaced by adapters out of cobalt-chromium. Until the end of 2008 in total 1.4% (n = 68 of the implanted titanium alloy neck adapters failed with an average time of 2.0 years (0.7 to 4.0 years postoperatively. All, but one, patients were male, their average age being 57.4 years (36 to 75 years and the average weight 102.3 kg (75 to 130 kg. The failures of neck adapters were divided into 66% with small CCD of 130° and 60% with head lengths of L or larger. Assuming an average time to failure of 2.8 years, the cumulative failure rate was calculated with 2.4%. Methods A series of adapter failures of titanium alloy modular neck adapters in combination with a titanium alloy modular short hip stem was investigated. For patients having received this particular implant combination risk factors were identified which were associated with the occurence of implant failure. A Kaplan-Meier survival-failure-analysis was conducted. The retrieved implants were analysed using microscopic and chemical methods. Modes of failure were simulated in biomechanical tests. Comparative tests included modular neck adapters made of titanium alloy and cobalt chrome alloy material. Results Retrieval examinations and biomechanical simulation revealed that primary micromotions initiated fretting within the modular tapered neck

  9. Enforsing a system approach to composite failure criteria for reliability analysis

    DEFF Research Database (Denmark)

    Dimitrov, Nikolay Krasimirov; Friis-Hansen, Peter; Berggreen, Christian

    2011-01-01

    parameters are random, multiple failure modes may be identified which will jeopardize the FORM analysis and a system approach should be applied to assure a correct analysis. Although crude Monte Carlo simulation automatically may account for such effects, time constraints limit its useability in problems...... challenges with the use of failure criteria, since composite materials are a discontinuous medium, which invoke multiple failure modes. Under deterministic conditions the material properties and the stress vector are constant and will result in a single dominating failure mode. When any of these input...... involving advanced FEM models. When applying more computationally efficient methods based on FORM/SORM it is important to carefully account for the multiple failure modes described by the failure criterion. The present paper discusses how to handle this problem and presents examples where reliability...

  10. Computer-tomography and its use in failure analysis; Computertomographie und deren Anwendung in der Schadensanalytik

    Energy Technology Data Exchange (ETDEWEB)

    Panzenboeck, Michael; Freitag, Caroline [Montanuniv. Leoben (Austria). Dept. Metallkunde und Werkstoffpruefung; Borchert, Marlies [Materials Center Leoben (Austria)

    2017-04-15

    In the last fifteen years computer-tomography has proven to be a valuable aid in the fields of medicine, materials technology and forensics. Nowadays it is hard to image non-destructive testing being carried out without its use. This article serves to demonstrate the power of the technique within the field of failure analysis with reference to two chosen case studies. The first case concerns the failure of magnetic valves, the second case focusses on the failure of corrosion resistant screws.

  11. Risk Assessment Planning for Airborne Systems: An Information Assurance Failure Mode, Effects and Criticality Analysis Methodology

    Science.gov (United States)

    2012-06-01

    that a physical vehicle or system could fail, one of the earliest methodologies used was FMEA , failure mode and effects analysis (MIL-P-1629, 1949...marginal, and minor failures, and included both direct effects and 23 secondary effects. The early FMEA process was refined, and utilized in the space...systems (Goddard, Validating the Safety of Real-Time Control Systems Using FMEA , 1993) which moves into the realm of failure modes which are not

  12. Preliminary Failure Modes and Effects Analysis of the US Massive Gas Injection Disruption Mitigation System Design

    Energy Technology Data Exchange (ETDEWEB)

    Lee C. Cadwallader

    2013-10-01

    This report presents the results of a preliminary failure modes and effects analysis (FMEA) of a candidate design for the ITER Disruption Mitigation System. This candidate is the Massive Gas Injection System that provides machine protection in a plasma disruption event. The FMEA was quantified with “generic” component failure rate data as well as some data calculated from operating facilities, and the failure events were ranked for their criticality to system operation.

  13. 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.

  14. 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.

  15. Deformation tests and failure process analysis of an anchorage structure

    Institute of Scientific and Technical Information of China (English)

    Zhao Tongbin; Yin Yanchun; Tan Yunliang; Song Yimin

    2015-01-01

    In order to study the failure process of an anchorage structure and the evolution law of the body’s defor-mation field, anchor push-out tests were carried out based on digital speckle correlation methods (DSCM). The stress distribution of the anchorage interface was investigated using the particle flow numerical simulation method. The results indicate that there are three stages in the deformation and fail-ure process of an anchorage structure:elastic bonding stage, a de-bonding stage and a failure stage. The stress distribution in the interface controls the stability of the structure. In the elastic bonding stage, the shear stress peak point of the interface is close to the loading end, and the displacement field gradually develops into a ‘V’ shape. In the de-bonding stage, there is a shear stress plateau in the center of the anchorage section, and shear strain localization begins to form in the deformation field. In the failure stage, the bonding of the interface fails rapidly and the shear stress peak point moves to the anchorage free end. The anchorage structure moves integrally along the macro-crack. The de-bonding stage is a research focus in the deformation and failure process of an anchorage structure, and plays an important guiding role in roadway support design and prediction of the stability of the surrounding rock.

  16. Principle of the central liquid supply system and its common failure analysis%中央供液系统原理及常见故障分析

    Institute of Scientific and Technical Information of China (English)

    陈伟豪; 谢伟柯; 姜东尧

    2012-01-01

    To improve the 4008s normal operation time and reduce the failure. We summarized all equipment failures in this paper and analyzed the reasons, Then we decided how to maintain the device according to results of the analysis. Through fault classification summary and decision of maintenance mehtods, the failure rate was reduced greatly. The 4008s' faults are caused by the pressure problem in the central liquid supply. The pressure is related to the liquid supply equipment and pipeline.%通过对中央供液系统原理及常见故障的分析,总结归纳具体原因,按照分析结果进行保养,提高费森尤斯4008S血透机正常运行时间,减少故障率.

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

    Directory of Open Access Journals (Sweden)

    N. Li

    2014-09-01

    Full Text Available 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.

  18. Failure analysis of dissimilar single-lap joints

    Directory of Open Access Journals (Sweden)

    F.A. Stuparu

    2016-03-01

    Full Text Available Single-lap joints made of aluminium and carbon fibre adherends of different thickness are tested to understand better the behaviour of such dissimilar joints. The overlap length and the thickness of the adhesive are kept constant. Local deformation fields are onitored by using the digital image correlation method. Peeling and shearing strains are investigated, emphasizing that peeling is important in the region where failure is initiated, towards an extremity of the overlap region. The use of only carbon fibre adherends is not recommended for a smaller thickness as an additional interface failure is produced and compromises the integrity of the lap joint. However, a dissimilar joint (aluminium-carbon with smaller thickness adherends succeeds to maintain the stiffness of the assembly, but its strength is diminished. The obtained results are suggesting that a complete monitoring of the failure processes in the overlap region can be fully understood only if local deformation measurements are possible.

  19. Reliability Analysis of Geotechnical Failure Modes for Vertical Wall Breakwaters

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Burcharth, H. F.

    2000-01-01

    Vertical wall breakwaters are usually designed as concrete caissons placed on the top of a rubble mound foundation or a rubble bedding layer. The purpose of the breakwater is usually to protect the area behind the breakwater from being flooded by large waves. The area protected can for example be...... that the accepted probability of failure also varies considerably which also can be observed from the actual observed failure rates....... be a harbour of small or large importance, an important industrial area or a heavily populated coast line. This implies that vertical wall breakwaters are used under quite different conditions and therefore the consequences of a complete or partial failure also are very different. This implies...

  20. Embedded mechatronic systems 1 analysis of failures, predictive reliability

    CERN Document Server

    El Hami, Abdelkhalak

    2015-01-01

    In operation, mechatronics embedded systems are stressed by loads of different causes: climate (temperature, humidity), vibration, electrical and electromagnetic. These stresses in components which induce failure mechanisms should be identified and modeled for better control. AUDACE is a collaborative project of the cluster Mov'eo that address issues specific to mechatronic reliability embedded systems. AUDACE means analyzing the causes of failure of components of mechatronic systems onboard. The goal of the project is to optimize the design of mechatronic devices by reliability. The projec

  1. Failure analysis of energy storage spring in automobile composite brake chamber

    Science.gov (United States)

    Luo, Zai; Wei, Qing; Hu, Xiaofeng

    2015-02-01

    This paper set energy storage spring of parking brake cavity, part of automobile composite brake chamber, as the research object. And constructed the fault tree model of energy storage spring which caused parking brake failure based on the fault tree analysis method. Next, the parking brake failure model of energy storage spring was established by analyzing the working principle of composite brake chamber. Finally, the data of working load and the push rod stroke measured by comprehensive test-bed valve was used to validate the failure model above. The experimental result shows that the failure model can distinguish whether the energy storage spring is faulted.

  2. 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

  3. Failure analysis of fuel cell electrodes using three-dimensional multi-length scale X-ray computed tomography

    Science.gov (United States)

    Pokhrel, A.; El Hannach, M.; Orfino, F. P.; Dutta, M.; Kjeang, E.

    2016-10-01

    X-ray computed tomography (XCT), a non-destructive technique, is proposed for three-dimensional, multi-length scale characterization of complex failure modes in fuel cell electrodes. Comparative tomography data sets are acquired for a conditioned beginning of life (BOL) and a degraded end of life (EOL) membrane electrode assembly subjected to cathode degradation by voltage cycling. Micro length scale analysis shows a five-fold increase in crack size and 57% thickness reduction in the EOL cathode catalyst layer, indicating widespread action of carbon corrosion. Complementary nano length scale analysis shows a significant reduction in porosity, increased pore size, and dramatically reduced effective diffusivity within the remaining porous structure of the catalyst layer at EOL. Collapsing of the structure is evident from the combination of thinning and reduced porosity, as uniquely determined by the multi-length scale approach. Additionally, a novel image processing based technique developed for nano scale segregation of pore, ionomer, and Pt/C dominated voxels shows an increase in ionomer volume fraction, Pt/C agglomerates, and severe carbon corrosion at the catalyst layer/membrane interface at EOL. In summary, XCT based multi-length scale analysis enables detailed information needed for comprehensive understanding of the complex failure modes observed in fuel cell electrodes.

  4. Development of an Automated Technique for Failure Modes and Effect Analysis

    DEFF Research Database (Denmark)

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

    1999-01-01

    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...

  5. Development of an automated technique for failure modes and effect analysis

    DEFF Research Database (Denmark)

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

    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...

  6. Analysis of contaminated field failure data for repairable systems

    DEFF Research Database (Denmark)

    Hansen, Christian Kornerup; Thyregod, Poul

    1991-01-01

    A simple model for electronic systems with repair, and a method for analyzing recorded field failure data for such systems are presented. The work performed has resulted in analytical results that may be used for assessing the product reliability. The method was originally developed for use under...

  7. Failure Analysis of Wind Turbines by Probability Density Evolution Method

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Liu, W.F.

    2013-01-01

    The aim of this study is to present an efficient and accurate method for estimation of the failure probability of wind turbine structures which work under turbulent wind load. The classical method for this is to fit one of the extreme value probability distribution functions to the extracted maxima...

  8. Iron deficiency in chronic heart failure : An international pooled analysis

    NARCIS (Netherlands)

    Klip, IJsbrand T.; Comin-Colet, Josep; Voors, Adriaan A.; Ponikowski, Piotr; Enjuanes, Cristina; Banasiak, Waldemar; Lok, Dirk J.; Rosentryt, Piotr; Torrens, Ainhoa; Polonski, Lech; van Veldhuisen, Dirk J.; van der Meer, Peter; Jankowska, Ewa A.

    2013-01-01

    Background Iron deficiency (ID) is an emerging problem in patients with chronic heart failure (HF) and can be a potential therapeutic target. However, not much is known about the prevalence, predictors, and prognosis of ID in patients with chronic HF. Methods In an international pooled cohort compri

  9. Analysis of soft rock mineral components and roadway failure mechanism

    Institute of Scientific and Technical Information of China (English)

    CHEN Jie

    2001-01-01

    The mineral components and microstructure of soft rock sampled from ro adway floor in Xiagou pit are determined by X-ray diffraction and scanning elec t ron microscope. Combined with the test of expansion and water softening prop erty of the soft rock, the roadway failure mechanism is analyzed, and the reason able repair supporting principle of roadway is put forward.

  10. FMEAssist: A knowledge-based approach to Failure Modes and Effects Analysis

    Science.gov (United States)

    Carnes, James R.; Cutts, Dannie E.

    1987-01-01

    A Failure Modes and Effects Analysis workstation (FMESassist) was designed for use during the development of the space station. It assists engineers in the complex task of tracking failures and their effects on the system. Engineers experience increased productivity through reduced clerical loads, reduced data inconsistency, and significantly reduced analysis time. System developments benefit from a more thorough analysis than was available using previous methods.

  11. Failure analysis of bolted joints in foam-core sandwich composites

    DEFF Research Database (Denmark)

    Zabihpoor, M.; Moslemian, Ramin; Afshin, M.

    2008-01-01

    This study represents an effort to predict the bearing strength, failure modes, and failure load of bolted joints in foam-core sandwich composites. The studied joints have been used in a light full composite airplane. By using solid laminates, a new design for the joint zone is developed....... These solid laminates include a number of glass plies with total thickness equal to core thickness. The effect of solid laminate size and interface angle of foam -solid laminate in the bonding zone on the bearing strength, failure loads and type of modes are investigated. The numerical study is performed...... using 3D FEM in ANSYS commercial code. Tsai-Wu failure criterion is used in the failure analysis. The results indicate that the most important parameter in the proposed joint zone design is the foam -solid laminate interface angle which plays an important role on the value of failure criterion (damage...

  12. Slope stability analysis for Valles Marineris, Mars: a numerical analysis of controlling conditions and failure types

    Science.gov (United States)

    Crosta, G.; Castellanza, R.; De Blasio, F.; Utili, S.

    2012-04-01

    Valles Marineris (VM hereafter) in the equatorial area of Mars exhibits several gravitative failures often involving the whole 6-8 km thickness of the valley walls. The failures have resulted in a series of long-runout landslides up to several hundred cubic kilometres in volume (Quantin et al., 2004), and the formation of sub-circular alcoves perched on the top. Several questions arise as to forces at play in the stability of the walls of VM, the geometrical shape of the alcoves and the shape and long-runout of the landslides (see for example Lucas et al., 2011). In this work, we concentrate on the stability analysis of the walls of VM with two precise questions in mind starting from past studies (Bigot-Cormier and Montgomery, 2006; Neuffer and Schultz, 2006, Schultz, 2002). The first concerns the properties of the materials that give origin to instability. We performed several finite element and discrete element calculations tailored to slope stability analysis based on the genuine shape of the walls of VM taken from the MOLA topographic data. We considered stratified and differently altered/degraded materials to define the range of physical mechanical properties required for failure to occur and to explain the discrete distribution of failures along the VM valley flanks. A second question addressed in this work is the geometrical shape of the sub-circular alcoves. Normally, these shapes are commonplace for slopes made of uniform and isotropic properties, and are also observed in subaqueous environment. We performed calculations taking into consideration the progressive failure in the slope showing the final results in terms of surface failure geometry. Bigot-Cormier, F., Montgomery, D.R. (2007) Valles Marineris landslides: Evidence for a strength limit to Martian relief? Earth and Planetary Science Letters, 260, 1-2, 15, 179-186 Lucas, A., Mangeney, A., Mège, D., and Bouchut, F., 2011. Influence of the scar geometry on landslide dynamics and deposits

  13. Analysis of Machine Learning Techniques for Heart Failure Readmissions.

    Science.gov (United States)

    Mortazavi, Bobak J; Downing, Nicholas S; Bucholz, Emily M; Dharmarajan, Kumar; Manhapra, Ajay; Li, Shu-Xia; Negahban, Sahand N; Krumholz, Harlan M

    2016-11-01

    The current ability to predict readmissions in patients with heart failure is modest at best. It is unclear whether machine learning techniques that address higher dimensional, nonlinear relationships among variables would enhance prediction. We sought to compare the effectiveness of several machine learning algorithms for predicting readmissions. Using data from the Telemonitoring to Improve Heart Failure Outcomes trial, we compared the effectiveness of random forests, boosting, random forests combined hierarchically with support vector machines or logistic regression (LR), and Poisson regression against traditional LR to predict 30- and 180-day all-cause readmissions and readmissions because of heart failure. We randomly selected 50% of patients for a derivation set, and a validation set comprised the remaining patients, validated using 100 bootstrapped iterations. We compared C statistics for discrimination and distributions of observed outcomes in risk deciles for predictive range. In 30-day all-cause readmission prediction, the best performing machine learning model, random forests, provided a 17.8% improvement over LR (mean C statistics, 0.628 and 0.533, respectively). For readmissions because of heart failure, boosting improved the C statistic by 24.9% over LR (mean C statistic 0.678 and 0.543, respectively). For 30-day all-cause readmission, the observed readmission rates in the lowest and highest deciles of predicted risk with random forests (7.8% and 26.2%, respectively) showed a much wider separation than LR (14.2% and 16.4%, respectively). Machine learning methods improved the prediction of readmission after hospitalization for heart failure compared with LR and provided the greatest predictive range in observed readmission rates. © 2016 American Heart Association, Inc.

  14. Reprioritization of failures in a system failure mode and effects analysis by decision making trial and evaluation laboratory technique

    Energy Technology Data Exchange (ETDEWEB)

    Seyed-Hosseini, S.M. [Industrial Engineering Department, Iran University of Science and Technology, Narmak, Tehran, 16844 (Iran, Islamic Republic of)]. E-mail: seyedhoseini@yahoo.com; Safaei, N. [Industrial Engineering Department, Iran University of Science and Technology, Narmak, Tehran, 16844 (Iran, Islamic Republic of)]. E-mail: nimasafaei@iust.ac.ir; Asgharpour, M.J. [Industrial Engineering Department, Iran University of Science and Technology, Narmak, Tehran, 16844 (Iran, Islamic Republic of)]. E-mail: asgharpour@iust.ac.ir

    2006-08-15

    In this paper an effective methodology related to decision making field has been developed for reprioritization of failure modes in a system Failure Mode and Effects Analysis (FMEA) for corrective actions. The proposed methodology can cover some of inherently shortcomings of conventional Risk Priority Number (RPN) method and like. The current prioritization methods have two main deficiencies as: they have not considered indirect relations between components and are deficient for systems with many subsystems or components. The proposed method called Decision Making Trial and Evaluation Laboratory (DEMATEL) is an effective approach for analyzing relation between components of a system in respect to its type (direct/indirect) and severity. The main advantages of DEMATEL are involving indirect relations in analyze, allocating as possible as unique ranks to alternatives and clustering alternatives in large systems. The demonstrated results have shown that DEMATEL method can be an efficient, complementary and confident approach for reprioritization of failure modes in a FMEA. For verification of proposed methodology, two illustrative practical examples are solved and obtained outcomes are reported.

  15. A new modification of summary-based analysis method for large software system testing

    Directory of Open Access Journals (Sweden)

    A. V. Sidorin

    2015-01-01

    Full Text Available The automated testing tools becoming a frequent practice require thorough computer-aided testing of large software systems, including system inter-component interfaces. To achieve a good coverage, one should overcome scalability problems of different methods of analysis. These problems arise from impossibility to analyze all the execution paths. The objective of this research is to build a method for inter-procedural analysis, which efficiency enables us to analyse large software systems (such as Android OS codebase as a whole for a reasonable time (no more than 4 hours. This article reviews existing methods of software analysis to detect their potential defects. It focuses on the symbolic execution method since it is widely used both in static analysis of source code and in hybrid analysis of object files and intermediate representation (concolic testing. The method of symbolic execution involves separation of a set of input data values into equivalence classes while choosing an execution path. The paper also considers advantages of this method and its shortcomings. One of the main scalability problems is related to inter-procedural analysis. Analysis time grows rapidly if an inlining method is used for inter-procedural analysis. So this work proposes a summary-based analysis method to solve scalability problems. Clang Static Analyzer, an open source static analyzer (a part of the LLVM project, has been chosen as a target system. It allows us to compare performance of inlining and summary-based inter-procedural analysis. A mathematical model for preliminary estimations is described in order to identify possible factors of performance improvement.

  16. Energy engineering analysis, Iowa Army Ammunition Plant, Burlington, Iowa. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Jonik, D.M.

    1982-06-22

    This Energy Engineering Analysis consists of the main report, three appendices, and a summary of annual energy consumption on a per-building basis. The main report identifies the purpose of the study, describes the existing and anticipated energy use trends, and defines and summarizes specific energy conservation projects recommended to achieve the goals stated in the Army Facilities Energy Plan. Appendices I, II and III, and the Annual Energy Consumption Summary include building information, weather data, cost data, and detailed computer-generated and manual calculations for each individual project. The analysis will enable ammunition plant personnel to identify energy conservation measures and meet Army energy reduction goals. The report includes: Energy consumption by fuel type Energy consumption trends ECAM projects Other potential projects Quick-fix management form Description of analyzed buildings In addition, the Analysis is a detailed data base consisting of: An analysis of building energy use Energy Conservation Measures applied to each analyzed building to be improved A set of marked-up prints from the survey indicating the conditions when surveyed.

  17. Failure Analysis of a Water Supply Pumping Pipeline System

    Directory of Open Access Journals (Sweden)

    Oscar Pozos-Estrada

    2016-09-01

    Full Text Available This paper describes the most important results of a theoretical, experimental and in situ investigation developed in connection with a water supply pumping pipeline failure. This incident occurred after power failure of the pumping system that caused the burst of a prestressed concrete cylinder pipe (PCCP. Subsequently, numerous hydraulic transient simulations for different scenarios and various air pockets combinations were carried out in order to fully validate the diagnostic. As a result, it was determined that small air pocket volumes located along the pipeline profile were recognized as the direct cause of the PCCP rupture. Further, a detail survey of the pipeline was performed using a combination of non-destructive technologies in order to determine if immediate intervention was required to replace PCC pipes. In addition, a hydraulic model was employed to analyze the behavior of air pockets located at high points of the pipeline.

  18. Analysis of Emergency Diesel Generators Failure Incidents in Nuclear Power Plants

    Science.gov (United States)

    Hunt, Ronderio LaDavis

    In early years of operation, emergency diesel generators have had a minimal rate of demand failures. Emergency diesel generators are designed to operate as a backup when the main source of electricity has been disrupted. As of late, EDGs (emergency diesel generators) have been failing at NPPs (nuclear power plants) around the United States causing either station blackouts or loss of onsite and offsite power. These failures occurred from a specific type called demand failures. This thesis evaluated the current problem that raised concern in the nuclear industry which was averaging 1 EDG demand failure/year in 1997 to having an excessive event of 4 EDG demand failure year which occurred in 2011. To determine the next occurrence of the extreme event and possible cause to an event of such happening, two analyses were conducted, the statistical and root cause analysis. Considering the statistical analysis in which an extreme event probability approach was applied to determine the next occurrence year of an excessive event as well as, the probability of that excessive event occurring. Using the root cause analysis in which the potential causes of the excessive event occurred by evaluating, the EDG manufacturers, aging, policy changes/ maintenance practices and failure components. The root cause analysis investigated the correlation between demand failure data and historical data. Final results from the statistical analysis showed expectations of an excessive event occurring in a fixed range of probability and a wider range of probability from the extreme event probability approach. The root-cause analysis of the demand failure data followed historical statistics for the EDG manufacturer, aging and policy changes/ maintenance practices but, indicated a possible cause regarding the excessive event with the failure components. Conclusions showed the next excessive demand failure year, prediction of the probability and the next occurrence year of such failures, with an

  19. Failure Analysis and Design Changes of Oxygen Pump Inducers

    Institute of Scientific and Technical Information of China (English)

    梁恒力; 陈佐一

    2001-01-01

    The failure of an oxygen pump inducer during a test run was found to be the result of flow induced vibration. Oscillating fluid mechanics theory was used to determine the oscillating flow field around the inducer for various external oscillating perturbation fretuencies. Enormous pressures can occur at some frequencies, which are sufficient to break the inducer. Some design changes were analyzed to improve the flow induced vibration characteristics.

  20. Failure Mode and Effects Analysis (FMEA) Introductory Overview

    Science.gov (United States)

    2012-06-14

    effects based on how severe they are, how often they might occur, and how easily we can find them. 3. Effects: the consequences of failure. The...Actions ! 0 l!1 .. requirE-ments ~ l=ailure 1-’rP.vP.ntion .., llP.tP.c::tion Completion Dato Action• Taken P. il "’ ; · .. "’ = 0 i;r= ~ ~ " S pnrg

  1. Endochronic theory for inelasticity and failure analysis of concrete structures

    Energy Technology Data Exchange (ETDEWEB)

    Bazant, Z.P.; Bhat, P.D.; Shieh, C.L.

    1976-12-01

    A gradual accumulation of inelastic strain can be most conveniently described in terms of the so-called intrinsic time, whose increment depends on the time increment as well as the strain increments. This approach, which gives a particularly simple description of irreversibility of strain at unloading and cyclic loading, was previously developed for metals and is extended herein to concrete by introducing the hydrostatic pressure sensitivity of inelastic strain, the inelastic dilatancy produced by deviator strains, and the strain-softening tendency at high stress. Failure envelopes are obtained as a collection of the peaks of stress-strain diagrams. By comparison with experimental data from the literature, it is demonstrated that the proposed model predicts quite closely: stress-strain diagrams for concretes of different strength; uniaxial, biaxial and triaxial stress-strain diagrams and failure envelopes; failure envelopes for combined torsion and compression, lateral strains and volume expansion in uniaxial and biaxial tests; the behavior of spirally confined concrete; hysteresis loops or repeated high compression; cyclic creep up to 10/sup 6/ cycles; the strain rate effect; the decrease of long time strength; and the increase of short-time strength due to low stress creep.

  2. Experimental and Numerical Failure Analysis of Adhesive Composite Joints

    Directory of Open Access Journals (Sweden)

    Farhad Asgari Mehrabadi

    2012-01-01

    Full Text Available In the first section of this work, a suitable data reduction scheme is developed to measure the adhesive joints strain energy release rate under pure mode-I loading, and in the second section, three types of adhesive hybrid lap-joints, that is, Aluminum-GFRP (Glass Fiber Reinforced Plastic, GFRP-GFRP, and Steel-GFRP were employed in the determination of adhesive hybrid joints strengths and failures that occur at these assemblies under tension loading. To achieve the aims, Double Cantilever Beam (DCB was used to evaluate the fracture state under the mode-I loading (opening mode and also hybrid lap-joint was employed to investigate the failure load and strength of bonded joints. The finite-element study was carried out to understand the stress intensity factors in DCB test to account fracture toughness using J-integral method as a useful tool for predicting crack failures. In the case of hybrid lap-joint tests, a numerical modeling was also performed to determine the adhesive stress distribution and stress concentrations in the side of lap-joint. Results are discussed in terms of their relationship with adhesively bonded joints and thus can be used to develop appropriate approaches aimed at using adhesive bonding and extending the lives of adhesively bonded repairs for aerospace structures.

  3. Fractographic analysis of tensile failures of aerospace grade composites

    Directory of Open Access Journals (Sweden)

    Masa Suresh Kumar

    2012-12-01

    Full Text Available This paper describes fractographic features observed in aerospace composites failed under tensile loads. Unidirectional Carbon Fibre Reinforced Plastic (UD CFRP and Unidirectional Glass Fibre Reinforced Plastic (UD GFRP composite specimens were fabricated and tested in tension. The morphology of fractured surfaces was studied at various locations to identify failure mechanism and characteristic fractographic features. CFRP composites displayed transverse crack propagation and the fracture surface showed three distinct regions, viz., crack origin, propagation and final failure. Significant variations in the fractographic features were noticed in crack propagation and final failure regions. Crack propagation region exhibited brittle fracture with chevron lines emanating from the crack origin. The entire crack propagation region exhibited radial marks on the individual fibre broken ends. On the other hand, the final fracture region revealed longitudinal matrix splitting and radial marks in majority of locations, and chop marks at some locations. The change in fracture mode in the final fracture was attributed to superimposition of bending loads. GFRP composites exhibited broom like fracture with extensive longitudinal splitting with radial marks present on individual fibre broken ends. Transverse fracture was observed at a few locations. These fracture features were analyzed and correlated with the loading conditions.

  4. An analysis of policy success and failure in formal evaluations of Australia's national mental health strategy (1992-2012).

    Science.gov (United States)

    Grace, Francesca C; Meurk, Carla S; Head, Brian W; Hall, Wayne D; Harris, Meredith G; Whiteford, Harvey A

    2017-05-30

    Heightened fiscal constraints, increases in the chronic disease burden and in consumer expectations are among several factors contributing to the global interest in evidence-informed health policy. The present article builds on previous work that explored how the Australian Federal Government applied five instruments of policy, or policy levers, to implement a series of reforms under the Australian National Mental Health Strategy (NMHS). The present article draws on theoretical insights from political science to analyse the relative successes and failures of these levers, as portrayed in formal government evaluations of the NMHS. Documentary analysis of six evaluation documents corresponding to three National Mental Health Plans was undertaken. Both the content and approach of these government-funded, independently conducted evaluations were appraised. An overall improvement was apparent in the development and application of policy levers over time. However, this finding should be interpreted with caution due to variations in evaluation approach according to Plan and policy lever. Tabulated summaries of the success and failure of each policy initiative, ordered by lever type, are provided to establish a resource that could be consulted for future policy-making. This analysis highlights the complexities of health service reform and underscores the limitations of narrowly focused empirical approaches. A theoretical framework is provided that could inform the evaluation and targeted selection of appropriate policy levers in mental health.

  5. Coupled Mechanical-Electrochemical-Thermal Analysis of Failure Propagation in Lithium-ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

    2016-07-28

    This is a presentation given at the 12th World Congress for Computational Mechanics on coupled mechanical-electrochemical-thermal analysis of failure propagation in lithium-ion batteries for electric vehicles.

  6. Failure Analysis of CCD Image Sensors Using SQUID and GMR Magnetic Current Imaging

    Science.gov (United States)

    Felt, Frederick S.

    2005-01-01

    During electrical testing of a Full Field CCD Image Senor, electrical shorts were detected on three of six devices. These failures occurred after the parts were soldered to the PCB. Failure analysis was performed to determine the cause and locations of these failures on the devices. After removing the fiber optic faceplate, optical inspection was performed on the CCDs to understand the design and package layout. Optical inspection revealed that the device had a light shield ringing the CCD array. This structure complicated the failure analysis. Alternate methods of analysis were considered, including liquid crystal, light and thermal emission, LT/A, TT/A SQUID, and MP. Of these, SQUID and MP techniques were pursued for further analysis. Also magnetoresistive current imaging technology is discussed and compared to SQUID.

  7. An institution-specific analysis of ACL reconstruction failure.

    Science.gov (United States)

    Frank, Rachel M; McGill, Kevin C; Cole, Brian J; Bush-Joseph, Charles A; Bach, Bernard R; Verma, Nikhil N; Slabaugh, Mark A

    2012-05-01

    The purpose of this study was to determine the most common causes of failed anterior cruciate ligament reconstruction (ACLR) using modern reconstructive techniques at a single, high-volume institution. In addition, the clinical outcomes of patients undergoing revision ACLR will be reported. The surgical logs of four senior knee surgeons were retrospectively reviewed for all patients who had undergone ACLR between 2002 and 2009. Patients were excluded if they did not have both the primary and revision surgery on the same knee with the same surgeon. Out of 1944 ACL reconstructions, 28 patients (56 reconstructions) were included in the study. Radiographic studies, operative reports, KT-1000 scores, and chart notes were used to identify all potential factors that may have led to failure. All patients were invited to return for a follow-up examination and survey. Of the 28 patients, the mean age at the index and revision procedure was 22 +/- 11 (range, 12 to 50) and 24 +/- 11 (range, 14 to 57), respectively. In 20 cases, the cause of failure was determined to be acute trauma (sports, work, or accident); in 1 case, the cause was biologic failure; while in 7 cases, the cause was technical error. During the study period the surgeons performed a combined total of 1944 procedures, for an overall failure rate of 1.8%. Twenty patients (71%) were available for follow-up at a mean 30.2 +/- 17.7 months. The overall postrevision outcomes were good to excellent for a majority of patients, with an average Lysholm score of 84 +/- 15.5 and International Knee Documentation Committee score of 77.2 +/- 13.8. The pre- and postoperative KT-1000 scores were 12.1 +/- 2.8 and 6.7 +/- 2.8, respectively. The results from this study suggest that traumatic re-injury, and not surgical/surgeon error, is the most common cause of ACLR failure using anatomic reconstructive principles and strong fixation. In addition, good to excellent outcomes following revision ACLR can be expected in the majority of

  8. Process-Oriented Development of Failure Reporting, Analysis, and Corrective Action System

    OpenAIRE

    Jae Hoon Lee; SungIl Chan; Joong Soon Jang

    2010-01-01

    Although failure reporting, analysis, and corrective action system (FRACAS) has two management perspectives, its tasks and related information, the previous researches and applications mainly have focused on the data management. This study is to develop a process-oriented FRACAS which supports the operation of the failure-related activities. The development procedures are (1) to define the reporting and analysis tasks, (2) to define the information to be used at each task, and (3) to design ...

  9. Using the failure mode and effects analysis model to improve parathyroid hormone and adrenocorticotropic hormone testing

    Directory of Open Access Journals (Sweden)

    Magnezi R

    2016-12-01

    Full Text Available Racheli Magnezi,1 Asaf Hemi,1 Rina Hemi2 1Department of Management, Public Health and Health Systems Management Program, Bar Ilan University, Ramat Gan, 2Endocrine Service Unit, Sheba Medical Center, Tel Aviv, Israel Background: Risk management in health care systems applies to all hospital employees and directors as they deal with human life and emergency routines. There is a constant need to decrease risk and increase patient safety in the hospital environment. The purpose of this article is to review the laboratory testing procedures for parathyroid hormone and adrenocorticotropic hormone (which are characterized by short half-lives and to track failure modes and risks, and offer solutions to prevent them. During a routine quality improvement review at the Endocrine Laboratory in Tel Hashomer Hospital, we discovered these tests are frequently repeated unnecessarily due to multiple failures. The repetition of the tests inconveniences patients and leads to extra work for the laboratory and logistics personnel as well as the nurses and doctors who have to perform many tasks with limited resources.Methods: A team of eight staff members accompanied by the Head of the Endocrine Laboratory formed the team for analysis. The failure mode and effects analysis model (FMEA was used to analyze the laboratory testing procedure and was designed to simplify the process steps and indicate and rank possible failures.Results: A total of 23 failure modes were found within the process, 19 of which were ranked by level of severity. The FMEA model prioritizes failures by their risk priority number (RPN. For example, the most serious failure was the delay after the samples were collected from the department (RPN =226.1.Conclusion: This model helped us to visualize the process in a simple way. After analyzing the information, solutions were proposed to prevent failures, and a method to completely avoid the top four problems was also developed. Keywords: failure mode

  10. 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.

  11. Relationship between angina pectoris and outcomes in patients with heart failure and reduced ejection fraction : an analysis of the Controlled Rosuvastatin Multinational Trial in Heart Failure (CORONA)

    NARCIS (Netherlands)

    Badar, Athar A.; Perez-Moreno, Ana Cristina; Jhund, Pardeep S.; Wong, Chih M.; Hawkins, Nathaniel M.; Cleland, John G. F.; van Veldhuisen, Dirk J.; Wikstrand, John; Kjekshus, John; Wedel, Hans; Watkins, Stuart; Gardner, Roy S.; Petrie, Mark C.; McMurray, John J. V.

    2014-01-01

    Aim Angina pectoris is common in patients with heart failure and reduced ejection fraction (HF-REF) but its relationship with outcomes has not been well defined. This relationship was investigated further in a retrospective analysis of the Controlled Rosuvastatin Multinational Trial in Heart Failure

  12. CLINICAL ANALYSIS OF OBSTRUCTIVE SLEEP APNEASYNDROME WITH ACUTE RESPIRATORY FAILURE

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Objective To study the clinical characteristics of obstructive sleep apnea syndrome (OSAS) induced acute respiratory failure. Methods The clinical and laboratory characteristics of 9 patients were reviewed. Results 9 patients (8 females, 1 male) presented with obesity and mental disturbance, with a BMI being 44.97 kg /m2, (45.25 kg/m2 in the fe male). The mean age of the group was 67.89 years (61~74 years). All had respiratory acidosis (mean pH 7.17), hypercapni a (mean PaCO2 94.10mmHg) (63.97~143.18mmHg), and hypoxemia (mean PaO2 39mmHg) (29.03~44.03mmHg). During periods of clinical stability all but 2 had awaken hypercapnia (mean PaCO2 46.73mmHg) (38.25~54.68mmHg). Four of the 9 patients had pulmonary function test showing FEV1>70%. Conclusion OSAS induced acute respiratory fail ure has a sudden onset and various presentations and can be reversed with early and proper treatment. The severity of abnormal pulmonary function was less than what would be expected to cause respiratory failure.

  13. Failure modes and effects criticality analysis and accelerated life testing of LEDs for medical applications

    Science.gov (United States)

    Sawant, M.; Christou, A.

    2012-12-01

    While use of LEDs in Fiber Optics and lighting applications is common, their use in medical diagnostic applications is not very extensive. Since the precise value of light intensity will be used to interpret patient results, understanding failure modes [1-4] is very important. We used the Failure Modes and Effects Criticality Analysis (FMECA) tool to identify the critical failure modes of the LEDs. FMECA involves identification of various failure modes, their effects on the system (LED optical output in this context), their frequency of occurrence, severity and the criticality of the failure modes. The competing failure modes/mechanisms were degradation of: active layer (where electron-hole recombination occurs to emit light), electrodes (provides electrical contact to the semiconductor chip), Indium Tin Oxide (ITO) surface layer (used to improve current spreading and light extraction), plastic encapsulation (protective polymer layer) and packaging failures (bond wires, heat sink separation). A FMECA table is constructed and the criticality is calculated by estimating the failure effect probability (β), failure mode ratio (α), failure rate (λ) and the operating time. Once the critical failure modes were identified, the next steps were generation of prior time to failure distribution and comparing with our accelerated life test data. To generate the prior distributions, data and results from previous investigations were utilized [5-33] where reliability test results of similar LEDs were reported. From the graphs or tabular data, we extracted the time required for the optical power output to reach 80% of its initial value. This is our failure criterion for the medical diagnostic application. Analysis of published data for different LED materials (AlGaInP, GaN, AlGaAs), the Semiconductor Structures (DH, MQW) and the mode of testing (DC, Pulsed) was carried out. The data was categorized according to the materials system and LED structure such as AlGaInP-DH-DC, Al

  14. The AMÉLIE project: failure mode, effects and criticality analysis: a model to evaluate the nurse medication administration process on the floor.

    Science.gov (United States)

    Nguyen, Christina; Côté, Justine; Lebel, Denis; Caron, Elaine; Genest, Christine; Mallet, Monia; Phan, Véronique; Bussières, Jean-François

    2013-02-01

    The objective of this article was to critically evaluate the causes of adverse drug events during the nurse medication administration process in paediatric care units in order to identify and prioritize interventions that need to be implemented. This is a failure mode, effects and criticality analysis (FMECA) study. A multidisciplinary committee composed of nurses, pharmacists, physicians and risk managers evaluated through consensus the process of administering medications at the Centre hospitalier universitaire de Sainte-Justine. By mapping the process, all the failure modes were identified and associated with at least one cause each. Using a summary grid, each failure mode was evaluated by rating frequency (from 1 to 9), likelihood of failure detection (from 0 to 100%) and severity (from 1 to 9) using adapted versions of already published scales. A 10-member committee was set up, and it met eight times between January and April 2010. In the two specialized paediatric units selected (n = 38 beds), an average number of approximately 20 000 drug doses was administered monthly from about 400 non-proprietary names. Through consensus, the committee identified 16 processes and 53 failure modes. While frequency and severity were based on perceptions that could be objectivized with local data and scientific documentation, the likelihood of detection was mainly based on individual perception. FMECA is a useful approach to improve the medication process. © 2011 Blackwell Publishing Ltd.

  15. Predictive factors for liver dysfunction and failure after hepatectomy: Analysis of 467 patients with hepatocellular carcinoma

    Institute of Scientific and Technical Information of China (English)

    Guangjin Du; Liqun Wu; Chengzhan Zhu; Rong Ye; Xin Yi

    2012-01-01

    Objective: The aim of our study was to analyze hepatic dysfunction and failure after hepatocellular carcinoma (HCC) resection and relationship of clinical and pathological factors.Methods: Clinical and pathological data of 467 HCC patients was retrospectively reviewed, who underwent liver resection from January 2002 to December 2008 in the Affiliated Hospital of Medical College, Qingdao University, and the post-resectional liver dysfunction and failure risk factors were analyzed by univariate and multivariate analysis.Results: The morbidity of post-resectional liver dysfunction and failure was 1.7% and 2.1%.The post-resectional liver dysfunction and failure after HCC hepatectomy into the statistical analysis: univariate analysis revealed preoperative platelet level ( 64 U/L), Child-Pugh classification (B), MELD score (≥ 9), intraoperative bleeding (≥ 1000 mL), blood transfusion were positive factors, multivariate analysis (Logistic) revealed that preoperative platelet level (0.983, 95% CI = 0.971-0.995) and intraoperative blood transfusion (3.145, 95% CI = 1.027-12.028) were independent risk factors for post-resectional liver dysfunction and failure.Conclusion: Prevented liver failure and liver dysfunction occurring after liver resection, it is the key to accurate preoperative assessment of liver function and the patient's reserved liver functional, precise hepatectomy and reasonable blockage of hepatic inflow.

  16. Progressive failure analysis of slope with strain-softening behaviour based on strength reduction method

    Institute of Scientific and Technical Information of China (English)

    Ke ZHANG; Ping CAO; Rui BAO

    2013-01-01

    Based on the strength reduction method and strain-softening model,a method for progressive failure analysis of strain-softening slopes was presented in this paper.The mutation is more pronounced in strain-softening analysis,and the mutation of displacement at slope crest was taken as critical failure criterion.An engineering example was provided to demonstrate the validity of the present method.This method was applied to a cut slope in an industry site.The results are as follows: (1) The factor of safety and the critical slip surface obtained by the present method are between those by peak and residual strength.The analysis with peak strength would lead to non-conservative results,but that with residual strength tends to be overly conservative.(2) The thickness of the shear zone considering strain-softening behaviour is narrower than that with non-softening analysis.(3) The failure of slope is the process of the initiation,propagation and connection of potential failure surface.The strength parameters are mobilized to a non-uniform degree while progressive failure occurs in the slope.(4) The factor of safety increases with the increase of residual shear strain threshold and elastic modulus.The failure mode of slope changes from shallow slip to deep slip.Poisson's ratio and dilation angle have little effect on the results.

  17. Failure analysis of blistered organic coatings on gray iron castings

    Science.gov (United States)

    Tianen, Matthew N.

    This study investigates the blistering failure of a two part coating consisting of talc-filled polyester resin and polyurethane primer on large gray iron castings. Surface metallography was performed and failed coating was characterized by scanning electron microscopy. Corrosion products were found inside of coating blisters. The proposed blistering mechanism is osmosis as a result of soluble species produced by the corrosion. It was believed that excessively thin primer layers resulted in a poor barrier to permeation of water, leading to blisters, and that a basecoat containing a corrosion inhibitor like zinc phosphate would reduce blistering. These hypotheses were tested with designed experiments using environmental testing in humidity and submersion environments. Thicker primer layers resulted in significant reductions in blistering and prolonged the time required before blister formation. A basecoat containing zinc phosphate was not found to be effective at reducing blistering in this coating system.

  18. Failure Analysis of Wind Turbines by Probability Density Evolution Method

    DEFF Research Database (Denmark)

    Sichani, Mahdi Teimouri; Nielsen, Søren R.K.; Liu, W.F.

    2013-01-01

    The aim of this study is to present an efficient and accurate method for estimation of the failure probability of wind turbine structures which work under turbulent wind load. The classical method for this is to fit one of the extreme value probability distribution functions to the extracted maxima....... This is not practical due to its excessive computational load. This problem can alternatively be tackled if the evolution of the probability density function (PDF) of the response process can be realized. The evolutionary PDF can then be integrated on the boundaries of the problem. For this reason we propose to use...... the Probability Density Evolution Method (PDEM). PDEM can alternatively be used to obtain the distribution of the extreme values of the response process by simulation. This approach requires less computational effort than integrating the evolution of the PDF; but may be less accurate. In this paper we present...

  19. IMPACT STRENGTH AND FAILURE ANALYSIS OF WELDED DAMASCUS STEEL

    Directory of Open Access Journals (Sweden)

    Rastislav Mintách

    2012-01-01

    Full Text Available The aim of this work was the experimental research of damascus steel from point of view of the structural analyze, impact strength and failure analyzes. The damascus steel was produced by method of forged welding from STN 41 4260 spring steel and STN 41 9312 tool steel. The damascus steel consisted of both 84 and 168 layers. The impact strength was experimentally determined for original steels and damascus steels after heat treatment in dependence on temperature in the range from -60 to 160 °C. It has been found that the impact strength of experimental steels decreased with decreasing temperature behind with correlated change of damage mode. In the case of experimental tests performed at high temperature ductile fracture was revealed and with decreasing temperature proportion of cleavage facets increased. Only the STN 41 9312 steel did not show considerable difference in values of the impact strength with changing temperature.

  20. Failure Analysis and Regeneration Performances Evaluation on Engine Lubricating Oil

    Science.gov (United States)

    Wang, X. L.; Zhang, G. N.; Zhang, J. Y.; Yin, Y. L.; Xu, Y.

    To investigate the behavior of failure and recycling of lubricating oils, three sorts of typical 10w-40 lubricating oils used in heavy-load vehicle including the new oil, waste oil and regeneration oil regenerated by self-researched green regeneration technology were selected. The tribology properties were tested by four-ball friction wear tester as well. The results indicated that the performance of anti-extreme pressure of regeneration oil increase by 34.1% compared with the waste one and its load- carrying ability is close to the new oil; the feature of wear spot are better than those of the waste oil and frictional coefficient almost reach the level of the new oil's. As a result, the performance of anti-wear and friction reducing are getting better obviously.

  1. Worsening Heart Failure Following Admission for Acute Heart Failure A Pooled Analysis of the PROTECT and RELAX-AHF Studies

    NARCIS (Netherlands)

    Davison, Beth A.; Metra, Marco; Cotter, Gad; Massie, Barry M.; Cleland, John G. F.; Dittrich, Howard C.; Edwards, Christopher; Filippatos, Gerasimos; Givertz, Michael M.; Greenberg, Barry; Ponikowski, Piotr; Voors, Adriaan A.; O'Connor, Christopher M.; Teerlink, John R.

    2015-01-01

    OBJECTIVES These studies conducted analyses to examine patient characteristics and outcomes associated with worsening heart failure (WHF). BACKGROUND WHF during an admission for acute heart failure (AHF) represents treatment failure and is a potential therapeutic target for clinical trials of AHF. M

  2. Random safety auditing, root cause analysis, failure mode and effects analysis.

    Science.gov (United States)

    Ursprung, Robert; Gray, James

    2010-03-01

    Improving quality and safety in health care is a major concern for health care providers, the general public, and policy makers. Errors and quality issues are leading causes of morbidity and mortality across the health care industry. There is evidence that patients in the neonatal intensive care unit (NICU) are at high risk for serious medical errors. To facilitate compliance with safe practices, many institutions have established quality-assurance monitoring procedures. Three techniques that have been found useful in the health care setting are failure mode and effects analysis, root cause analysis, and random safety auditing. When used together, these techniques are effective tools for system analysis and redesign focused on providing safe delivery of care in the complex NICU system.

  3. Asymptotics on Semiparametric Analysis of Multivariate Failure Time Data Under the Additive Hazards Model

    Institute of Scientific and Technical Information of China (English)

    Huan-bin Liu; Liu-quan Sun; Li-xing Zhu

    2005-01-01

    Many survival studies record the times to two or more distinct failures on each subject. The failures may be events of different natures or may be repetitions of the same kind of event. In this article, we consider the regression analysis of such multivariate failure time data under the additive hazards model. Simple weighted estimating functions for the regression parameters are proposed, and asymptotic distribution theory of the resulting estimators are derived. In addition, a class of generalized Wald and generalized score statistics for hypothesis testing and model selection are presented, and the asymptotic properties of these statistics are examined.

  4. Failure analysis of multiple delaminated composite plates due to bending and impact

    Indian Academy of Sciences (India)

    P K Parhi; S K Bhattacharyya; P K Sinha

    2001-04-01

    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 eight-noded isoparametric quadratic elements to develop the finite element analysis procedure. Composite plates are assumed to contain both single and multiple delaminations. For the case of impact, Newmark time integration algorithm is employed for solving the time dependent multiple equations of the plate and the impactor. Tsai-Wu failure criterion is used to check for failure of the laminate for both the cases. To investigate the first ply failure, parametric studies are made for different cases by varying the size and number of delaminations as well as the stacking sequences and boundary conditions.

  5. Real-time automated failure analysis for on-orbit operations

    Science.gov (United States)

    Kirby, Sarah; Lauritsen, Janet; Pack, Ginger; Ha, Anhhoang; Jowers, Steven; Mcnenny, Robert; Truong, The; Dell, James

    1993-01-01

    A system which is to provide real-time failure analysis support to controllers at the NASA Johnson Space Center Control Center Complex (CCC) for both Space Station and Space Shuttle on-orbit operations is described. The system employs monitored systems' models of failure behavior and model evaluation algorithms which are domain-independent. These failure models are viewed as a stepping stone to more robust algorithms operating over models of intended function. The described system is designed to meet two sets of requirements. It must provide a useful failure analysis capability enhancement to the mission controller. It must satisfy CCC operational environment constraints such as cost, computer resource requirements, verification, and validation. The underlying technology and how it may be used to support operations is also discussed.

  6. Probabilistic Analysis of Failures Mechanisms of Large Dams

    NARCIS (Netherlands)

    Shams Ghahfarokhi, G.

    2014-01-01

    Risk and reliability analysis is presently being performed in almost all fields of engineering depending upon the specific field and its particular area. Probabilistic risk analysis (PRA), also called quantitative risk analysis (QRA) is a central feature of hydraulic engineering structural design.

  7. Multiscale Modeling Methods for Analysis of Failure Modes in Foldcore Sandwich Panels

    Science.gov (United States)

    Sturm, R.; Schatrow, P.; Klett, Y.

    2015-12-01

    The paper presents an homogenised core model suitable for use in the analysis of fuselage sandwich panels with folded composite cores under combined loading conditions. Within a multiscale numerical design process a failure criterion was derived for describing the macroscopic behaviour of folded cores under combined loading using a detailed foldcore micromodel. The multiscale modelling method was validated by simulation of combined compression/bending failure of foldcore sandwich panels.

  8. Photogrammetric analysis of slope failures feeding the head of the Illgraben debris flow channel

    Science.gov (United States)

    Bennett, G. L.; Molnar, P.; Eisenbeiss, H.; McArdell, B. W.

    2012-04-01

    Our understanding of slope failure is restricted by a lack of inventories of sufficient size and directly measured volumes. We used digital photogrammetry to produce a multi-temporal record of erosion of a rock slope in the Illgraben. From this we extracted an inventory of ~2500 slope failures for 3 epochs of 6/7 years between 1986 and 2005 ranging over 6 orders of magnitude in volume. Through analysis of their magnitude-frequency, volume-area and depth-slope gradient relations we aimed to understand the characteristics of slope failure at the head of this active alpine debris-flow catchment. The slope failure volumes follow a characteristic magnitude-frequency distribution with a roll-over at 50m3 and a power-law tail between ~200m3 and 1.6x106m3 with an exponent of 1.65. We compared different methods to estimate the power law scaling exponent and found the maximum likelihood estimator to be the most accurate. Conversely, least squares regression on the probability density function consistently underestimated the exponent. Slope failure volume scales with failure area as a power law with an exponent of 1.1. This exponent is low for the bedrock nature of the slope in comparison with worldwide studies of bedrock and soil landslides and likely results from the highly fractured and incohesive nature of the quartzitic bedrock of the study slope. Comparing the results for different epochs we find that the magnitude-frequency and volume-area relationships are reasonably time-invariant demonstrating their general nature for the setting. We interpret the magnitude-frequency distribution of slope failure volumes as the result of two separate slope failure processes. Type (1) failures are frequent, small slides and slumps within the weathered layer of highly fractured rock and loose sediment. These make up the roll-over of the distribution. Type (2) failures are less frequent rockslides and rockfalls within the internal bedded and fractured slope along pre

  9. Identification of hidden failures in process control systems through function-oriented system analysis

    Energy Technology Data Exchange (ETDEWEB)

    Jalashgar, A.

    1997-05-01

    The main subject of this thesis is to identify hidden failures in process control systems by developing and using a function-oriented system analysis method. Qualitative failure analysis and the characteristics of the classical failure analysis methods and function-oriented modelling methods are covered. The general limitations of the methods in connection with the identification and representation of hidden failures are discussed. The discussion has led to the justification of developing and using a function-oriented system analysis method to identify and represent the capabilities of the system components, which realize different sets of functions in connection with different sets of goals that the system must achieve. A terminology is introduced to define the basic aspects of technical systems including goals, functions, capabilities and physical structure. A function-oriented system analysis method using this terminology and a tailored combination of the two function-oriented modelling approaches, is also introduced. It is then explained how the method can be applied in the identification and representation of hidden failures. The building blocks of a knowledge-oriented system to perform the diagnosis on the basis of the developed method are equally described. A prototype of the knowledge-based system is developed to demonstrate the applicability of the function-oriented system analysis method and the knowledge-based system. The prototype is implemented within the object-oriented software environment G2. (au) 65 ills., 32 refs.

  10. Cognitive Impairment and Heart Failure: Systematic Review and Meta-Analysis.

    Science.gov (United States)

    Cannon, Jane A; Moffitt, Peter; Perez-Moreno, Ana Cristina; Walters, Matthew R; Broomfield, Niall M; McMurray, John J V; Quinn, Terence J

    2017-06-01

    Cognitive impairment and dementia are associated with a range of cardiovascular conditions, including hypertension, coronary artery disease, and atrial fibrillation. We aimed to describe the association with heart failure, summarizing published data to give estimates of prevalence, incidence, and relative risk of cognitive impairment/dementia in heart failure. We searched multidisciplinary databases including MEDLINE (OVID), EMBASE (OVID), CINAHL (EBSCO), PsychINFO (EBSCO), Web of Science (Thomson Reuters), and CENTRAL (Cochrane Library) from inception until May 31, 2015. All relevant studies looking at cognitive impairment/dementia in heart failure were included. Studies were selected by 2 independent reviewers using prespecified inclusion/exclusion criteria. Where data allowed, we performed meta-analysis and pooled results using random effects models. From 18,000 titles, 37 studies were eligible (n = 8411 participants). Data from 4 prospective cohorts (n = 2513 participants) suggest greater cognitive decline in heart failure compared with non-heart failure over the longer term. These data were not suitable for meta-analysis. In case control studies describing those with and without heart failure (n = 4 papers, 1414 participants) the odds ratio for cognitive impairment in the heart failure population was 1.67 (95% confidence interval 1.15-2.42). Prevalence of cognitive impairment in heart failure cohorts (n = 26 studies, 4176 participants) was 43% (95% confidence interval 30-55). This review suggests a substantial proportion of patients with heart failure have concomitant cognitive problems. This has implications for planning treatment and services. These data do not allow us to comment on causation, and further work is needed to describe the underlying pathophysiology. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Security Analysis of Selected AMI Failure Scenarios Using Agent Based Game Theoretic Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Abercrombie, Robert K [ORNL; Schlicher, Bob G [ORNL; Sheldon, Frederick T [ORNL

    2014-01-01

    Information security analysis can be performed using game theory implemented in dynamic Agent Based Game Theoretic (ABGT) simulations. Such simulations can be verified with the results from game theory analysis and further used to explore larger scale, real world scenarios involving multiple attackers, defenders, and information assets. We concentrated our analysis on the Advanced Metering Infrastructure (AMI) functional domain which the National Electric Sector Cyber security Organization Resource (NESCOR) working group has currently documented 29 failure scenarios. The strategy for the game was developed by analyzing five electric sector representative failure scenarios contained in the AMI functional domain. From these five selected scenarios, we characterize them into three specific threat categories affecting confidentiality, integrity and availability (CIA). The analysis using our ABGT simulation demonstrates how to model the AMI functional domain using a set of rationalized game theoretic rules decomposed from the failure scenarios in terms of how those scenarios might impact the AMI network with respect to CIA.

  12. The Analysis of Anemia in Chronic Heart Failure

    Institute of Scientific and Technical Information of China (English)

    Yuan Guiyi; Wu Wei; Luo Yilong; Li Yiqing; Zhou Shuxian; Fang Chang

    2006-01-01

    objectives To demonstrate the phenomena and explore the causes of anemia in patients with chronic heart failure (CHF). Methods To observe the phenomena of anemia in patients with CHF, a total of 276 patients with CHF were included in this retrospective study. The clinical characteristics of the patients are: mean age 69.2±11.0 years; male 151,female 125; NYHA Ⅲ and Ⅳ 115 (41.7%). Results ①Among the 276 patients with CHF, 81 (29.4%)had anemia (Mean hemoglobulin concentration 101.5±13.0g/L). ② Patients with Anemia were more likely to be female and to have greater NYHA (Ⅲ or Ⅳ) (P<0.05), higher serum creatinine, as well as lower serum albumin and low-density lipoprotein levels (P<0.01).③ A weak negative correlation was also noted between the level of NYHA and hemoglobulin. ④ There was no significant difference in age, the primary cardiac etiology of the CHF, the history of diabetes, left ventricular end diastolic diameter, and left ventricular ejection fraction between CHF patient with and without anemia. Conclusions The prevalence of anemia is high among patients with CHF. The anemia patients with CHF tend to be female, have greater cardiac and renal functional impairment, but with lower serum albumin and LDL that suggests some degree of malnutrition.

  13. 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, heat transfer analysis was conducted to predict the temperature history of the roll by 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.

  14. 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.

  15. Electromechanical actuators affected by multiple failures: Prognostic method based on spectral analysis techniques

    Science.gov (United States)

    Belmonte, D.; Vedova, M. D. L. Dalla; Ferro, C.; Maggiore, P.

    2017-06-01

    The proposal of prognostic algorithms able to identify precursors of incipient failures of primary flight command electromechanical actuators (EMA) is beneficial for the anticipation of the incoming failure: an early and correct interpretation of the failure degradation pattern, in fact, can trig an early alert of the maintenance crew, who can properly schedule the servomechanism replacement. An innovative prognostic model-based approach, able to recognize the EMA progressive degradations before his anomalous behaviors become critical, is proposed: the Fault Detection and Identification (FDI) of the considered incipient failures is performed analyzing proper system operational parameters, able to put in evidence the corresponding degradation path, by means of a numerical algorithm based on spectral analysis techniques. Subsequently, these operational parameters will be correlated with the actual EMA health condition by means of failure maps created by a reference monitoring model-based algorithm. In this work, the proposed method has been tested in case of EMA affected by combined progressive failures: in particular, partial stator single phase turn to turn short-circuit and rotor static eccentricity are considered. In order to evaluate the prognostic method, a numerical test-bench has been conceived. Results show that the method exhibit adequate robustness and a high degree of confidence in the ability to early identify an eventual malfunctioning, minimizing the risk of fake alarms or unannounced failures.

  16. Epilepsy surgery failure in children: a quantitative and qualitative analysis

    Science.gov (United States)

    Englot, Dario J.; Han, Seunggu J.; Rolston, John D.; Ivan, Michael E.; Kuperman, Rachel A.; Chang, Edward F.; Gupta, Nalin; Sullivan, Joseph E.; Auguste, Kurtis I.

    2015-01-01

    Object Resection is a safe and effective treatment option for children with pharmacoresistant focal epilepsy, but some patients continue experience seizures after surgery. While most studies of pediatric epilepsy surgery focus on predictors of postoperative seizure outcome, these factors are often not modifiable, and the reasons for surgical failure may remain unclear. Methods The authors performed a retrospective cohort study of children and adolescents who received focal resective surgery for pharmacoresistant epilepsy. Both quantitative and qualitative analyses of factors associated with persistent postoperative seizures were conducted. Results Records were reviewed from 110 patients, ranging in age from 6 months to 19 years at the time of surgery, who underwent a total of 115 resections. At a mean 3.1-year follow-up, 76% of patients were free of disabling seizures (Engel Class I outcome). Seizure freedom was predicted by temporal lobe surgery compared with extra-temporal resection, tumor or mesial temporal sclerosis compared with cortical dysplasia or other pathologies, and by a lower preoperative seizure frequency. Factors associated with persistent seizures (Engel Class II–IV outcome) included residual epileptogenic tissue adjacent to the resection cavity (40%), an additional epileptogenic zone distant from the resection cavity (32%), and the presence of a hemispheric epilepsy syndrome (28%). Conclusions While seizure outcomes in pediatric epilepsy surgery may be improved by the use of high-resolution neuroimaging and invasive electrographic studies, a more aggressive resection should be considered in certain patients, including hemispherectomy if a hemispheric epilepsy syndrome is suspected. Family counseling regarding treatment expectations is critical, and reoperation may be warranted in select cases. PMID:25127098

  17. 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

  18. 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.

  19. 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.

  20. Molecular analysis of the relationship between specific vaginal bacteria and bacterial vaginosis metronidazole therapy failure.

    Science.gov (United States)

    Wang, B; Xiao, B B; Shang, C G; Wang, K; Na, R S; Nu, X X; Liao, Q

    2014-10-01

    Bacterial vaginosis frequently persists, even after treatment. The role of some strains of bacteria associated with bacterial vaginosis treatment failure remains poorly defined. The aim of our study was to define the risk of bacterial vaginosis treatment failure, including pre-treatment detection of specific vaginal bacteria. Bacterial vaginosis is present when the Nugent score is ≥7 and the modified Amsel criteria is positive. Women with bacterial vaginosis were treated with intravaginal metronidazole gel nightly for 5 nights. The 454 pyrosequencing method was used to detect bacteria in vaginal fluid. By univariate analysis, a history of bacterial vaginosis, intrauterine device use and the presence of Facklamia, Corynebacterium and Veillonella were significantly associated with bacterial vaginosis treatment failure. Lactobacillus crispatus, Lactobacillus pentosus and Megasphaera were significantly associated with curing bacterial vaginosis. After logistic regression analysis and detection of these bacteria for test-of-cure, we found that women who had a history of bacterial vaginosis had a higher incidence of bacterial vaginosis treatment failure, whereas women with L. crispatus had a lower incidence of treatment failure. Post-treatment sexual activity was not associated with the treatment effect. Our data suggested that treatment failure may be not caused by drug resistance. Rather, it has a closer relationship with the failed restoration of lactobacilli.

  1. Influence of initial reservoir level and gate failure in dam safety analysis. Stochastic approach

    Science.gov (United States)

    Gabriel-Martin, Ivan; Sordo-Ward, Alvaro; Garrote, Luis; Castillo, Luis G.

    2017-07-01

    This study proposes a stochastic methodology to assess the influence of considering variable reservoir levels prior to the arrival of floods in hydrological dam safety; introducing probability associated to gate failure scenarios. The methodology was applied to the Riaño dam (northern Spain) by analyzing the effects of incoming floods with return periods ranging from one to 10,000 years. We studied four scenarios with different gate failure rates and compared the results assuming initial reservoir level equal to the maximum level allowed in the reservoir under normal operation conditions with those considering variable initial reservoir levels. The ratio of the return periods associated to different reference levels reached in the reservoir considering variable over constant initial level ranged from 2.0 to 4.1. The ratio of the return periods obtained assuming gate failure and no failure for the same reference reservoir level ranged up to 93, 160 and 240 depending on the gate failure rate assigned. The ratio of the return periods associated to different maximum spillway discharges considering variable over constant initial reservoir level ranged from 2.5 to 6.1. However, the ratio of the return periods obtained assuming gate failure and no failure for the same discharge ranged from 0.7 to 1.1, showing no influence of gate failure. For the study case, our analysis highlighted the importance of considering the fluctuation of the initial reservoir levels and different gate failure scenarios, emphasizing that the return periods of maximum levels reached in the reservoir and maximum outflows are the variables that best represent dam and downstream hydrological safety.

  2. WE-G-BRA-08: Failure Modes and Effects Analysis (FMEA) for Gamma Knife Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Y; Bhatnagar, J; Bednarz, G; Flickinger, J; Arai, Y; Huq, M Saiful [Department of Radiation Oncology, University of Pittsburgh Cancer Institute, Pittsburgh, PA (United States); Vacsulka, J; Monaco, E; Niranjan, A; Lunsford, L Dade [Department of Neurological Surgery, University of Pittsburgh Medical Center, Pittsburgh, PA (United States); Feng, W [Dept of Radiation Oncology, New York Presbyterian Hospital/Columbia Univ Medical Center, New York, NY (United States)

    2015-06-15

    Purpose: To perform a failure modes and effects analysis (FMEA) study for Gamma Knife (GK) radiosurgery processes at our institution based on our experience with the treatment of more than 13,000 patients. Methods: A team consisting of medical physicists, nurses, radiation oncologists, neurosurgeons at the University of Pittsburgh Medical Center and an external physicist expert was formed for the FMEA study. A process tree and a failure mode table were created for the GK procedures using the Leksell GK Perfexion and 4C units. Three scores for the probability of occurrence (O), the severity (S), and the probability of no detection (D) for failure modes were assigned to each failure mode by each professional on a scale from 1 to 10. The risk priority number (RPN) for each failure mode was then calculated (RPN = OxSxD) as the average scores from all data sets collected. Results: The established process tree for GK radiosurgery consists of 10 sub-processes and 53 steps, including a sub-process for frame placement and 11 steps that are directly related to the frame-based nature of the GK radiosurgery. Out of the 86 failure modes identified, 40 failure modes are GK specific, caused by the potential for inappropriate use of the radiosurgery head frame, the imaging fiducial boxes, the GK helmets and plugs, and the GammaPlan treatment planning system. The other 46 failure modes are associated with the registration, imaging, image transfer, contouring processes that are common for all radiation therapy techniques. The failure modes with the highest hazard scores are related to imperfect frame adaptor attachment, bad fiducial box assembly, overlooked target areas, inaccurate previous treatment information and excessive patient movement during MRI scan. Conclusion: The implementation of the FMEA approach for Gamma Knife radiosurgery enabled deeper understanding of the overall process among all professionals involved in the care of the patient and helped identify potential

  3. Automated Production Flow Line Failure Rate Mathematical Analysis with Probability Theory

    Directory of Open Access Journals (Sweden)

    Tan Chan Sin

    2014-12-01

    Full Text Available Automated lines have been widely used in the industries especially for mass production and to customize product. Productivity of automated line is a crucial indicator to show the output and performance of the production. Failure or breakdown of station or mechanisms is commonly occurs in the automated line in real condition due to the technological and technical problem which is highly affect the productivity. The failure rates of automated line are not express or analyse in terms of mathematic form. This paper presents the mathematic analysis by using probability theory towards the failure condition in automated line. The mathematic express for failure rates can produce and forecast the output of productivity accurately

  4. Numerical Analysis on Failure Modes and Mechanisms of Mine Pillars under Shear Loading

    Directory of Open Access Journals (Sweden)

    Tianhui Ma

    2016-01-01

    Full Text Available Severe damage occurs frequently in mine pillars subjected to shear stresses. The empirical design charts or formulas for mine pillars are not applicable to orebodies under shear. In this paper, the failure process of pillars under shear stresses was investigated by numerical simulations using the rock failure process analysis (RFPA 2D software. The numerical simulation results indicate that the strength of mine pillars and the corresponding failure mode vary with different width-to-height ratios and dip angles. With increasing dip angle, stress concentration first occurs at the intersection between the pillar and the roof, leading to formation of microcracks. Damage gradually develops from the surface to the core of the pillar. The damage process is tracked with acoustic emission monitoring. The study in this paper can provide an effective means for understanding the failure mechanism, planning, and design of mine pillars.

  5. failure analysis of a uav flight control system using markov analysis

    African Journals Online (AJOL)

    eobe

    2016-01-01

    Jan 1, 2016 ... model system with varied failure scenario such as those described above [1]. ... Active Transport Molecular Communication (ATMC) ... Figure 2 Research flowchart. Figure 3 ... operational failure of the entire FCS. The servo ...

  6. Smoking, radiotherapy, diabetes and osteoporosis as risk factors for dental implant failure: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    Hui Chen

    Full Text Available BACKGROUND: There are conflicting reports as to the association between smoking, radiotherapy, diabetes and osteoporosis and the risk of dental implant failure. We undertook a meta-analysis to evaluate the association between smoking, radiotherapy, diabetes and osteoporosis and the risk of dental implant failure. METHODS: A comprehensive research on MEDLINE and EMBASE, up to January 2013, was conducted to identify potential studies. References of relevant studies were also searched. Screening, data extraction and quality assessment were conducted independently and in duplicate. A random-effects meta-analysis was used to pool estimates of relative risks (RRs with 95% confidence intervals (CIs. RESULTS: A total of 51 studies were identified in this meta-analysis, with more than 40,000 dental implants placed under risk-threatening conditions. The pooled RRs showed a direct association between smoking (n = 33; RR = 1.92; 95% CI, 1.67-2.21 and radiotherapy (n = 16; RR = 2.28; 95% CI, 1.49-3.51 and the risk of dental implant failure, whereas no inverse impact of diabetes (n = 5; RR = 0.90; 95% CI, 0.62-1.32 on the risk of dental implant failure was found. The influence of osteoporosis on the risk of dental implant failure was direct but not significant (n = 4; RR = 1.09; 95% CI, 0.79-1.52. The subgroup analysis indicated no influence of study design, geographical location, length of follow-up, sample size, or mean age of recruited patients. CONCLUSIONS: Smoking and radiotherapy were associated with an increased risk of dental implant failure. The relationship between diabetes and osteoporosis and the risk of implant failure warrant further study.

  7. DETECTING CONGESTIVE HEART FAILURE USING HEART RATE SEQUENTIAL TREND ANALYSIS PLOT

    Directory of Open Access Journals (Sweden)

    SRINIVAS KUNTAMALLA,

    2010-12-01

    Full Text Available Heart rate variability analysis is gaining acceptance as a potential non-invasive means of autonomic nervous system assessment in research as well as clinical domains. In this study, a nonlinear analysis method is developed to detect congestive heart failure. The data obtained from an online and widely used public database (i.e., MIT/BIH physionet database, is used for testing the performance of the method. The method developed is based on the sequential trend analysis plot of heart rate variability and correlates well with the characteristic autonomic nervous system regulations in congestive heart failure. The proposed method can be used for screening as well as diagnosing the heart failure patients. The algorithm is computationally simple and can be implemented in a real time processing hardware. This method classifies 31 out of 32 subjects and has the highest discrimination power in terms of sensitivity, specificity and accuracy.

  8. AODV routing overhead analysis based on link failure probability in MANET

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qin-juan; WU Mu-qing; ZHEN Yan; SHANG Cui-li

    2010-01-01

    This article puts forward an Ad-hoc on-demand distance vector routing(AODV)routing overhead analysis method in mobile Ad-hoc network(MANET).Although multiple routing protocols have been proposed to improve the performance,scarcely any paper analyzed the routing overhead caused by routing setup and maintenance processes in mathematical way.Routing overhead consumes part of network resources and limits the supported traffic in the network.For on-demand routing protocols like AODV,the routing overhead depends on the link failure probability to a great extent.This article analyzes the collision probability caused by hidden-node problem and the impact on link failure probability.In chain and rectangle scenarios,it presents a mathematical analysis of the theoretical routing overhead of AODV protocol based on link failure probability.Simulations on OPNET 14.5platform match well with the theoretical derivation which confirms the effectiveness of the analysis method.

  9. Upper bound analysis for deep tunnel face with joined failure mechanism of translation and rotation

    Institute of Scientific and Technical Information of China (English)

    许敬叔; 杜佃春; 杨子汉

    2015-01-01

    A joined failure mechanism of translation and rotation was proposed for the stability analysis of deep tunnel face, and the upper bound solution of supporting force of deep tunnel was calculated under pore water pressure. The calculations were based on limit analysis method of upper bound theory, with the employment of non-associated Mohr-Coulomb flow rule. Nonlinear failure criterion was adopted. Optimized analysis was conducted for the effects of the tunnel depth, pore water pressure coefficient, the initial cohesive force and nonlinear coefficient on supporting force. The upper bound solutions are obtained by optimum method. Results are listed and compared with the previously published solutions for the verification of correctness and effectiveness. The failure shapes are presented, and results are discussed for different pore water pressure coefficients and nonlinear coefficients of tunnel face.

  10. 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

  11. 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.

  12. Failure mode analysis of silicon-based intracortical microelectrode arrays in non-human primates

    Science.gov (United States)

    Barrese, James C.; Rao, Naveen; Paroo, Kaivon; Triebwasser, Corey; Vargas-Irwin, Carlos; Franquemont, Lachlan; Donoghue, John P.

    2013-12-01

    Objective. Brain-computer interfaces (BCIs) using chronically implanted intracortical microelectrode arrays (MEAs) have the potential to restore lost function to people with disabilities if they work reliably for years. Current sensors fail to provide reliably useful signals over extended periods of time for reasons that are not clear. This study reports a comprehensive retrospective analysis from a large set of implants of a single type of intracortical MEA in a single species, with a common set of measures in order to evaluate failure modes. Approach. Since 1996, 78 silicon MEAs were implanted in 27 monkeys (Macaca mulatta). We used two approaches to find reasons for sensor failure. First, we classified the time course leading up to complete recording failure as acute (abrupt) or chronic (progressive). Second, we evaluated the quality of electrode recordings over time based on signal features and electrode impedance. Failure modes were divided into four categories: biological, material, mechanical, and unknown. Main results. Recording duration ranged from 0 to 2104 days (5.75 years), with a mean of 387 days and a median of 182 days (n = 78). Sixty-two arrays failed completely with a mean time to failure of 332 days (median = 133 days) while nine array experiments were electively terminated for experimental reasons (mean = 486 days). Seven remained active at the close of this study (mean = 753 days). Most failures (56%) occurred within a year of implantation, with acute mechanical failures the most common class (48%), largely because of connector issues (83%). Among grossly observable biological failures (24%), a progressive meningeal reaction that separated the array from the parenchyma was most prevalent (14.5%). In the absence of acute interruptions, electrode recordings showed a slow progressive decline in spike amplitude, noise amplitude, and number of viable channels that predicts complete signal loss by about eight years. Impedance measurements showed

  13. What is Scanning Probe Microscopy? And How Can It Be Used In Failure Analysis?

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, A.; Tangyunyong, P.

    1999-03-26

    Scanning probe microscopy (SPM) techniques are not suitable as global defect-localization tools. They can, however, pinpoint the exact location of the defects once the approximate locations of the defects have been identified by other failure analysis techniques. SPM techniques also provide information such as 3-D topology, current, surface potential, and 2-D dopant profile that may not be readily obtainable with other techniques. This information, coupled with the unparalleled spatial resolution and high detection sensitivity can be used by failure analysts for root cause analysis.

  14. Model-OA wind turbine generator - Failure modes and effects analysis

    Science.gov (United States)

    Klein, William E.; Lali, Vincent R.

    1990-01-01

    The results failure modes and effects analysis (FMEA) conducted for wind-turbine generators are presented. The FMEA was performed for the functional modes of each system, subsystem, or component. The single-point failures were eliminated for most of the systems. The blade system was the only exception. The qualitative probability of a blade separating was estimated at level D-remote. Many changes were made to the hardware as a result of this analysis. The most significant change was the addition of the safety system. Operational experience and need to improve machine availability have resulted in subsequent changes to the various systems, which are also reflected in this FMEA.

  15. Applying healthcare failure mode and effect analysis to patient pain management in the anesthesia recovery period

    Institute of Scientific and Technical Information of China (English)

    Zhao-Ping Xue; Hong-Yan Li; Rui-Tong Guan; Si Chen

    2016-01-01

    Objective: To standardize pain management in the anesthesia recovery period and improve the effects of analgesia on acute postoperative pain. Methods: Using healthcare failure mode and effect analysis (HFMEA), we analyzed the primary cause of patients' pain and subsequently determined the process and risk priority number (RPN). Results: Actions were taken to improve patients' pain. After using HFMEA, the experimental group's visual analog scale (VAS) scores were lower than those of the control group at 1 h and at discharge from the post-anesthetic intensive care unit (PAICU). The differences were statistically significant (P Conclusions: The application of failure mode and effect analysis can relieve pain and improve the quality of nursing.

  16. Analysis of failures of waterproofing cladding layers of terracotta tiles

    Directory of Open Access Journals (Sweden)

    Koláčný Milan

    2017-01-01

    Full Text Available The article is focused on one of the most important roof cladding layers – the waterproofing cladding layer of terracotta tiles. Its detailed analysis covers the main waterproofing cladding layers in terms of their material characteristics and installation methods. The article concludes by formulating principles for the correct design of the main waterproofing layer/construction.

  17. A novel approach of testability modeling and analysis for PHM systems based on failure evolution mechanism

    Institute of Scientific and Technical Information of China (English)

    Tan Xiaodong; Qiu Jing; Liu Guanjun; Lv Kehong; Yang Shuming; Wang Chao

    2013-01-01

    Prognostics and health management (PHM) significantly improves system availability and reliability,and reduces the cost of system operations.Design for testability (DFT) developed concurrently with system design is an important way to improve PHM capability.Testability modeling and analysis are the foundation of DFT.This paper proposes a novel approach of testability modeling and analysis based on failure evolution mechanisms.At the component level,the fault progression-related information of each unit under test (UUT) in a system is obtained by means of failure modes,evolution mechanisms,effects and criticality analysis (FMEMECA),and then the failure-symptom dependency can be generated.At the system level,the dynamic attributes of UUTs are assigned by using the bond graph methodology,and then the symptom-test dependency can be obtained by means of the functional flow method.Based on the failure-symptom and symptom-test dependencies,testability analysis for PHM systems can be realized.A shunt motor is used to verify the application of the approach proposed in this paper.Experimental results show that this approach is able to be applied to testability modeling and analysis for PHM systems very well,and the analysis results can provide a guide for engineers to design for testability in order to improve PHM performance.

  18. [Failure modes and effects analysis in the prescription, validation and dispensing process].

    Science.gov (United States)

    Delgado Silveira, E; Alvarez Díaz, A; Pérez Menéndez-Conde, C; Serna Pérez, J; Rodríguez Sagrado, M A; Bermejo Vicedo, T

    2012-01-01

    To apply a failure modes and effects analysis to the prescription, validation and dispensing process for hospitalised patients. A work group analysed all of the stages included in the process from prescription to dispensing, identifying the most critical errors and establishing potential failure modes which could produce a mistake. The possible causes, their potential effects, and the existing control systems were analysed to try and stop them from developing. The Hazard Score was calculated, choosing those that were ≥ 8, and a Severity Index = 4 was selected independently of the hazard Score value. Corrective measures and an implementation plan were proposed. A flow diagram that describes the whole process was obtained. A risk analysis was conducted of the chosen critical points, indicating: failure mode, cause, effect, severity, probability, Hazard Score, suggested preventative measure and strategy to achieve so. Failure modes chosen: Prescription on the nurse's form; progress or treatment order (paper); Prescription to incorrect patient; Transcription error by nursing staff and pharmacist; Error preparing the trolley. By applying a failure modes and effects analysis to the prescription, validation and dispensing process, we have been able to identify critical aspects, the stages in which errors may occur and the causes. It has allowed us to analyse the effects on the safety of the process, and establish measures to prevent or reduce them. Copyright © 2010 SEFH. Published by Elsevier Espana. All rights reserved.

  19. On the relative efficiency of using summary statistics versus individual-level data in meta-analysis.

    Science.gov (United States)

    Lin, D Y; Zeng, D

    2010-06-01

    Meta-analysis is widely used to synthesize the results of multiple studies. Although meta-analysis is traditionally carried out by combining the summary statistics of relevant studies, advances in technologies and communications have made it increasingly feasible to access the original data on individual participants. In the present paper, we investigate the relative efficiency of analyzing original data versus combining summary statistics. We show that, for all commonly used parametric and semiparametric models, there is no asymptotic efficiency gain by analyzing original data if the parameter of main interest has a common value across studies, the nuisance parameters have distinct values among studies, and the summary statistics are based on maximum likelihood. We also assess the relative efficiency of the two methods when the parameter of main interest has different values among studies or when there are common nuisance parameters across studies. We conduct simulation studies to confirm the theoretical results and provide empirical comparisons from a genetic association study.

  20. medplot: a web application for dynamic summary and analysis of longitudinal medical data based on R.

    Science.gov (United States)

    Ahlin, Črt; Stupica, Daša; Strle, Franc; Lusa, Lara

    2015-01-01

    In biomedical studies the patients are often evaluated numerous times and a large number of variables are recorded at each time-point. Data entry and manipulation of longitudinal data can be performed using spreadsheet programs, which usually include some data plotting and analysis capabilities and are straightforward to use, but are not designed for the analyses of complex longitudinal data. Specialized statistical software offers more flexibility and capabilities, but first time users with biomedical background often find its use difficult. We developed medplot, an interactive web application that simplifies the exploration and analysis of longitudinal data. The application can be used to summarize, visualize and analyze data by researchers that are not familiar with statistical programs and whose knowledge of statistics is limited. The summary tools produce publication-ready tables and graphs. The analysis tools include features that are seldom available in spreadsheet software, such as correction for multiple testing, repeated measurement analyses and flexible non-linear modeling of the association of the numerical variables with the outcome. medplot is freely available and open source, it has an intuitive graphical user interface (GUI), it is accessible via the Internet and can be used within a web browser, without the need for installing and maintaining programs locally on the user's computer. This paper describes the application and gives detailed examples describing how to use the application on real data from a clinical study including patients with early Lyme borreliosis.

  1. medplot: a web application for dynamic summary and analysis of longitudinal medical data based on R.

    Directory of Open Access Journals (Sweden)

    Črt Ahlin

    Full Text Available In biomedical studies the patients are often evaluated numerous times and a large number of variables are recorded at each time-point. Data entry and manipulation of longitudinal data can be performed using spreadsheet programs, which usually include some data plotting and analysis capabilities and are straightforward to use, but are not designed for the analyses of complex longitudinal data. Specialized statistical software offers more flexibility and capabilities, but first time users with biomedical background often find its use difficult. We developed medplot, an interactive web application that simplifies the exploration and analysis of longitudinal data. The application can be used to summarize, visualize and analyze data by researchers that are not familiar with statistical programs and whose knowledge of statistics is limited. The summary tools produce publication-ready tables and graphs. The analysis tools include features that are seldom available in spreadsheet software, such as correction for multiple testing, repeated measurement analyses and flexible non-linear modeling of the association of the numerical variables with the outcome. medplot is freely available and open source, it has an intuitive graphical user interface (GUI, it is accessible via the Internet and can be used within a web browser, without the need for installing and maintaining programs locally on the user's computer. This paper describes the application and gives detailed examples describing how to use the application on real data from a clinical study including patients with early Lyme borreliosis.

  2. A Report on Simulation-Driven Reliability and Failure Analysis of Large-Scale Storage Systems

    Energy Technology Data Exchange (ETDEWEB)

    Wan, Lipeng [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wang, Feiyi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Oral, H. Sarp [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Vazhkudai, Sudharshan S. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cao, Qing [Univ. of Tennessee, Knoxville, TN (United States)

    2014-11-01

    High-performance computing (HPC) storage systems provide data availability and reliability using various hardware and software fault tolerance techniques. Usually, reliability and availability are calculated at the subsystem or component level using limited metrics such as, mean time to failure (MTTF) or mean time to data loss (MTTDL). This often means settling on simple and disconnected failure models (such as exponential failure rate) to achieve tractable and close-formed solutions. However, such models have been shown to be insufficient in assessing end-to-end storage system reliability and availability. We propose a generic simulation framework aimed at analyzing the reliability and availability of storage systems at scale, and investigating what-if scenarios. The framework is designed for an end-to-end storage system, accommodating the various components and subsystems, their interconnections, failure patterns and propagation, and performs dependency analysis to capture a wide-range of failure cases. We evaluate the framework against a large-scale storage system that is in production and analyze its failure projections toward and beyond the end of lifecycle. We also examine the potential operational impact by studying how different types of components affect the overall system reliability and availability, and present the preliminary results

  3. A Modeling Technique and Representation of Failure in the Analysis of Triaxial Braided Carbon Fiber Composites

    Science.gov (United States)

    Littell, Justin D.; Binienda, Wieslaw K.; Goldberg, Robert K.; Roberts, Gary D.

    2008-01-01

    Quasi-static tests have been performed on triaxially braided carbon fiber composite materials with large unit cell sizes. The effects of different fibers and matrix materials on the failure mode were investigated. Simulations of the tests have been performed using the transient dynamic finite element code, LS-DYNA. However, the wide range of failure modes observed for the triaxial braided carbon fiber composites during tests could not be simulated using composite material models currently available within LS-DYNA. A macroscopic approach has been developed that provides better simulation of the material response in these materials. This approach uses full-field optical measurement techniques to measure local failures during quasi-static testing. Information from these experiments is then used along with the current material models available in LS-DYNA to simulate the influence of the braided architecture on the failure process. This method uses two-dimensional shell elements with integration points through the thickness of the elements to represent the different layers of braid along with a new analytical method for the import of material stiffness and failure data directly. The present method is being used to examine the effect of material properties on the failure process. The experimental approaches used to obtain the required data will be described, and preliminary results of the numerical analysis will be presented.

  4. Risk Factors Leading to Free Flap Failure: Analysis From the National Surgical Quality Improvement Program Database.

    Science.gov (United States)

    Sanati-Mehrizy, Paymon; Massenburg, Benjamin B; Rozehnal, John M; Ingargiola, Michael J; Hernandez Rosa, Jonatan; Taub, Peter J

    2016-11-01

    The objective of this study was to identify risk factors for free flap failure among various anatomically based free flap subgroups. The 2005 to 2012 American College of Surgeons National Surgical Quality Improvement Program database was queried for patients undergoing microvascular free tissue transfer based on current procedural terminology codes. Univariate analysis was performed to identify any association between flap failure and the following factors: age, gender, race, body mass index (BMI), diabetes, smoking, alcohol use, hypertension, intraoperative transfusion, functional health status, American Society of Anesthesiologists class, operative time, and flap location. Factors yielding a significance of P free flap reconstruction met inclusion criteria. Multivariate logistic regression identified BMI (adjusted odds ratio [AOR] = 1.07, P = 0.004) and male gender (AOR = 2.16, P = 0.033) as independent risk factors for flap failure. Among the "breast flaps" subgroup, BMI (AOR = 1.075, P = 0.012) and smoking (AOR = 3.35, P = 0.02) were independent variables associated with flap failure. In "head and neck flaps," operative time (AOR = 1.003, P = 0.018) was an independent risk factor for flap failure. No independent risk factors were identified for the "extremity flaps" or "trunk flaps" subtypes. BMI, smoking, and operative time were identified as independent risk factors for free flap failure among all flaps or within flap subsets.

  5. The analysis of repeated failures of pipelines in Kal'chinskoe oil field

    Science.gov (United States)

    Shavlov, E. N.; Brusnik, O. V.; Lukjanov, V. G.

    2016-09-01

    The paper presents the chemical analysis of oilfield water and hydraulic analysis of the liquid flow in Kal'chinskoe oil field pipeline that allow detecting the causes of the internal corrosion processes. The inhibitor protection is suggested to reduce the corrosion rate in the pipelines of Kal'chinskoe oil field. Based on the analysis of the pipeline failures, it is suggested to replace steel pipes by fiberglass pipes.

  6. Progressive failure analysis of composite structure based on micro- and macro-mechanics models

    Institute of Scientific and Technical Information of China (English)

    孙志刚; 阮绍明; 陈磊; 宋迎东

    2015-01-01

    Based on parameter design language, a program of progressive failure analysis in composite structures is proposed. In this program, the relationship between macro- and micro-mechanics is established and the macro stress distribution of the composite structure is calculated by commercial finite element software. According to the macro-stress, the damaged point is found and the micro-stress distribution of representative volume element is calculated by finite-volume direct averaging micromechanics (FVDAM). Compared with the results calculated by failure criterion based on macro-stress field (the maximum stress criteria and Hashin criteria) and micro-stress field (Huang model), it is proven that the failure analysis based on macro- and micro-mechanics model is feasible and efficient.

  7. A Fuzzy Approach of the Optimal Analysis Based of Failure States in Manufacturing Systems

    Directory of Open Access Journals (Sweden)

    E. Minca

    2012-12-01

    Full Text Available This article proposes an algorithm for prognosis in optimal analysis of manufacturing systems. Uncertain knowledge of such task requires for specific reasoning and adaptive model base of fuzzy logic analyzes. The proposed method performs the interfaces between the results provided by the fuzzy supervision model and the algorithm witch identify the real state of the monitored system. The supervisory system sends failure signals described in a fuzzy approach. These ones represent inputs values in the system of failure optimal analysis which identifies the current degradation states by recurrent identification cycle. The proposed algorithm has also predictive component capable to determine the possible evolution of the system state towards a critical state of failure.

  8. Failure Analysis of Main Flame Deflector Nelson Studs

    Science.gov (United States)

    Long, Victoria

    2009-01-01

    NASA Structures engineers submitted two Nelson refractory studs from the main flame deflector at Launch Complex (LC) 39 A for analysis when they were observed to be missing a significant amount of material after launch. The damaged stud and an unused comparative stud were analyzed by macroscopic and microscopic examination along with metallographic evaluation of the microstructure. The stud lost material due to a combination of erosion and corrosion. Plain carbon steel readily forms an oxide layer in the coastal launch environment at Kennedy Space Center. The blast during a launch removes this brittle oxide layer, which then forms again post-launch, thereby further removing material. No indications of melting were observed.

  9. Failure analysis on China power grid based on power law

    Institute of Scientific and Technical Information of China (English)

    Xiaofeng WENG; Yiguang HONG; Ancheng XUE; Shengwei MEI

    2006-01-01

    This paper is concerned with the mechanism of blackouts in China power system from the viewpoint of self-organized criticality. By using two estimation algorithms of scaled window variance (SWV) and rescaled rangestatistics (R/S), this paper studies the blackout data in China power system during 1988-1997. The result of analysis shows that the blackout data of 1994-1997 coincides well with the autocorrelation. Furthermore, it is found that the function of blackout probability vs. blackout size exhibits power law distribution.

  10. Analysis of Moderator System Failure Accidents by Using New Method for Wolsong-1 CANDU 6 Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Dongsik; Kim, Jonghyun; Cho, Cheonhwey [Atomic Creative Technology Co., Ltd., Daejeon (Korea, Republic of); Kim, Sungmin [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2013-05-15

    To reconfirm the safety of moderator system failure accidents, the safety analysis by using the reactor physics code, RFSP-IST, coupled with the thermal hydraulics code, CATHENA is performed additionally. In the present paper, the newly developed analysis method is briefly described and the results obtained from the moderator system failure accident simulations for Wolsong-1 CANDU 6 reactor by using the new method are summarized. The safety analysis of the moderator system failure accidents for Wolsong-1 CANDU 6 reactor was carried out by using the new code system, i. e., CATHENA and RFSP-IST, instead of the non-IST old codes, namely, SMOKIN G-2 and MODSTBOIL. The analysis results by using the new method revealed as same with the results by using the old method that the fuel integrity is warranted because the localized power peak remained well below the limits and, most importantly, the reactor operation enters into the self-shutdown mode due to the substantial loss of moderator D{sub 2}O inventory from the moderator system. In the analysis results obtained by using the old method, it was predicted that the ROP trip conditions occurred for the transient cases which are also studied in the present paper. But, in the new method, it was found that the ROP trip conditions did not occur. Consequently, in the safety analysis performed additionally by using the new method, the safety of moderator system failure accidents was reassured. In the future, the new analysis method by using the IST codes instead of the non-IST old codes for the moderator system failure accidents is strongly recommended.

  11. Learning from Trending, Precursor Analysis, and System Failures

    Energy Technology Data Exchange (ETDEWEB)

    Youngblood, R. W. [Idaho National Laboratory, Idaho Falls, ID (United States); Duffey, R. B. [Idaho National Laboratory, Idaho Falls, ID (United States)

    2015-11-01

    Models of reliability growth relate current system unreliability to currently accumulated experience. But “experience” comes in different forms. Looking back after a major accident, one is sometimes able to identify previous events or measurable performance trends that were, in some sense, signaling the potential for that major accident: potential that could have been recognized and acted upon, but was not recognized until the accident occurred. This could be a previously unrecognized cause of accidents, or underestimation of the likelihood that a recognized potential cause would actually operate. Despite improvements in the state of practice of modeling of risk and reliability, operational experience still has a great deal to teach us, and work has been going on in several industries to try to do a better job of learning from experience before major accidents occur. It is not enough to say that we should review operating experience; there is too much “experience” for such general advice to be considered practical. The paper discusses the following: 1. The challenge of deciding what to focus on in analysis of operating experience. 2. Comparing what different models of learning and reliability growth imply about trending and precursor analysis.

  12. 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.

  13. Advances on the Failure Analysis of the Dam—Foundation Interface of Concrete Dams

    Directory of Open Access Journals (Sweden)

    Luis Altarejos-García

    2015-12-01

    Full Text Available Failure analysis of the dam-foundation interface in concrete dams is characterized by complexity, uncertainties on models and parameters, and a strong non-linear softening behavior. In practice, these uncertainties are dealt with a well-structured mixture of experience, best practices and prudent, conservative design approaches based on the safety factor concept. Yet, a sound, deep knowledge of some aspects of this failure mode remain unveiled, as they have been offset in practical applications by the use of this conservative approach. In this paper we show a strategy to analyse this failure mode under a reliability-based approach. The proposed methodology of analysis integrates epistemic uncertainty on spatial variability of strength parameters and data from dam monitoring. The purpose is to produce meaningful and useful information regarding the probability of occurrence of this failure mode that can be incorporated in risk-informed dam safety reviews. In addition, relationships between probability of failure and factors of safety are obtained. This research is supported by a more than a decade of intensive professional practice on real world cases and its final purpose is to bring some clarity, guidance and to contribute to the improvement of current knowledge and best practices on such an important dam safety concern.

  14. A Procedure for Modeling Structural Component/Attachment Failure Using Transient Finite Element Analysis

    Science.gov (United States)

    Lovejoy, Andrew E.; Jegley, Dawn C. (Technical Monitor)

    2007-01-01

    Structures often comprise smaller substructures that are connected to each other or attached to the ground by a set of finite connections. Under static loading one or more of these connections may exceed allowable limits and be deemed to fail. Of particular interest is the structural response when a connection is severed (failed) while the structure is under static load. A transient failure analysis procedure was developed by which it is possible to examine the dynamic effects that result from introducing a discrete failure while a structure is under static load. The failure is introduced by replacing a connection load history by a time-dependent load set that removes the connection load at the time of failure. The subsequent transient response is examined to determine the importance of the dynamic effects by comparing the structural response with the appropriate allowables. Additionally, this procedure utilizes a standard finite element transient analysis that is readily available in most commercial software, permitting the study of dynamic failures without the need to purchase software specifically for this purpose. The procedure is developed and explained, demonstrated on a simple cantilever box example, and finally demonstrated on a real-world example, the American Airlines Flight 587 (AA587) vertical tail plane (VTP).

  15. Sedation for pediatric radiological procedures: analysis of potential causes of sedation failure and paradoxical reactions

    Energy Technology Data Exchange (ETDEWEB)

    Karian, V.E.; Burrows, P.E.; Connor, L. [Dept. of Radiology, Children' s Hospital, Boston, MA (United States); Zurakowski, D. [Dept. of Biostatistics, Children' s Hospital, Boston, MA (United States); Mason, K.P. [Dept. of Anesthesiology, Children' s Hospital, Boston, MA (United States)

    1999-11-01

    Background. Sedation for diagnostic imaging and interventional radiologic procedures in pediatrics has greatly increased over the past decade. With appropriate patient selection and monitoring, serious adverse effects are infrequent, but failure to sedate and paradoxical reactions do occur. Objective. The purpose of this study was to determine, among patients undergoing sedation for radiologic procedures, the incidence of sedation failure and paradoxical reaction to pentobarbital and to identify potentially correctable causes. Materials and methods. Records of 1665 patients who were sedated in the radiology department from 1 November 1997 to 1 July 1998 were reviewed. Patients failing sedation or experiencing paradoxical reaction were compared with respect to sex, age group, diagnosis, scan type, time of day, NPO status, use of IV contrast and type of sedation agent using the Fisher exact test, Pearson chi-square, analysis of variance (ANOVA), the Student t-test, and logistic regression. Results. Data analysis revealed a sedation failure rate of 1 % and paradoxical reaction rate of 1.2 %. Stepwise multiple logistic regression revealed that the only significant independent multivariate predictor of failure was the need for the administration of a combination of pentobarbital, fentanyl, and midazolam IV. Conclusion. The low rate of sedation failure and paradoxical reactions to pentobarbital was near optimal and probably cannot be improved with the currently available sedatives. (orig.)

  16. Failure analysis of parameter-induced simulation crashes in climate models

    Directory of Open Access Journals (Sweden)

    D. D. Lucas

    2013-01-01

    Full Text Available Simulations using IPCC-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 apply 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 predicts 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 are determined through a global sensitivity analysis. Combinations of 8 parameters related to ocean mixing and viscosity from three different POP2 parameterizations are 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.

  17. 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.

  18. Failure mode and effects analysis of witnessing protocols for ensuring traceability during IVF.

    Science.gov (United States)

    Rienzi, Laura; Bariani, Fiorenza; Dalla Zorza, Michela; Romano, Stefania; Scarica, Catello; Maggiulli, Roberta; Nanni Costa, Alessandro; Ubaldi, Filippo Maria

    2015-10-01

    Traceability of cells during IVF is a fundamental aspect of treatment, and involves witnessing protocols. Failure mode and effects analysis (FMEA) is a method of identifying real or potential breakdowns in processes, and allows strategies to mitigate risks to be developed. To examine the risks associated with witnessing protocols, an FMEA was carried out in a busy IVF centre, before and after implementation of an electronic witnessing system (EWS). A multidisciplinary team was formed and moderated by human factors specialists. Possible causes of failures, and their potential effects, were identified and risk priority number (RPN) for each failure calculated. A second FMEA analysis was carried out after implementation of an EWS. The IVF team identified seven main process phases, 19 associated process steps and 32 possible failure modes. The highest RPN was 30, confirming the relatively low risk that mismatches may occur in IVF when a manual witnessing system is used. The introduction of the EWS allowed a reduction in the moderate-risk failure mode by two-thirds (highest RPN = 10). In our experience, FMEA is effective in supporting multidisciplinary IVF groups to understand the witnessing process, identifying critical steps and planning changes in practice to enable safety to be enhanced.

  19. Failure analysis of parameter-induced simulation crashes in climate models

    Directory of Open Access Journals (Sweden)

    D. D. Lucas

    2013-08-01

    Full Text Available 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.

  20. Summary and Statistical Analysis of the First AIAA Sonic Boom Prediction Workshop

    Science.gov (United States)

    Park, Michael A.; Morgenstern, John M.

    2014-01-01

    A summary is provided for the First AIAA Sonic Boom Workshop held 11 January 2014 in conjunction with AIAA SciTech 2014. Near-field pressure signatures extracted from computational fluid dynamics solutions are gathered from nineteen participants representing three countries for the two required cases, an axisymmetric body and simple delta wing body. Structured multiblock, unstructured mixed-element, unstructured tetrahedral, overset, and Cartesian cut-cell methods are used by the participants. Participants provided signatures computed on participant generated and solution adapted grids. Signatures are also provided for a series of uniformly refined workshop provided grids. These submissions are propagated to the ground and loudness measures are computed. This allows the grid convergence of a loudness measure and a validation metric (dfference norm between computed and wind tunnel measured near-field signatures) to be studied for the first time. Statistical analysis is also presented for these measures. An optional configuration includes fuselage, wing, tail, flow-through nacelles, and blade sting. This full configuration exhibits more variation in eleven submissions than the sixty submissions provided for each required case. Recommendations are provided for potential improvements to the analysis methods and a possible subsequent workshop.

  1. Risk Analysis of the Space Shuttle: Pre-Challenger Bayeisan Prediction of Failure

    Energy Technology Data Exchange (ETDEWEB)

    Dana L. Kelly

    2008-02-01

    Dalal et al performed a statistical analysis of field and nozzle O-ring data collected prior to the ill-fated launch of the Challenger in January 1986. The purpose of their analysis was to show how statistical analysis could be used to provide information to decisionmakers prior to the launch, information that could have been expected to lead to a decision to abort the launch due to the low temperatures (~30o F.) present at the launch pad on the morning of the scheduled launch. Dalal et al. performed a frequentist analysis of the O-ring data, and found that a logistic regression model provided a relatively good fit to the past data. In the second portion of their paper, Dalal et al. propagated parameter uncertainties through the fitted logistic regression model in order to estimate the probability of shuttle failure due to O-ring failure at the estimated launch temperature of ~30o F. Because their analysis was frequentist in nature, probability distributions representing epistemic uncertainty in the input parameters were not available, and the authors had to resort to an approximate approach based on bootstrap confidence intervals. In this paper, we will re-evaluate the analyses of Dalal et al. from a Bayesian perspective. Markov chain Monte Carlo (MCMC) sampling will be used to sample from the joint posterior distribution of the model parameters, and to sample from the posterior predictive distributions at the estimated launch temperature, a temperature that had not been observed in prior launches of the space shuttle. Uncertainties, which are represented by probability distributions in the Bayesian approach, are propagated through the model to obtain a probability distribution for O-ring failure, and subsequently for shuttle failure as a result of O-ring failure. No approximations are required in the Bayesian approach and the resulting distributions can be input to a decision analysis to obtain expected utility for the decision to launch.

  2. Failure mode and effect analysis in asset maintenance : a multiple case study in the process industry

    NARCIS (Netherlands)

    Braaksma, Jan; Klingenberg, W.; Veldman, J.

    2013-01-01

    Failure mode and effect analysis (FMEA) is an important method for designing and prioritising preventive maintenance activities and is often used as the basis for preventive maintenance planning. Although FMEA was studied extensively, most of the published work so far covers FMEA concept design. Lit

  3. Failure mode and effect analysis in asset maintenance: a multiple case study in the process industry

    NARCIS (Netherlands)

    Braaksma, A.J.J.; Klingenberg, W.; Veldman, J.

    2013-01-01

    Failure mode and effect analysis (FMEA) is an important method for designing and prioritising preventive maintenance activities and is often used as the basis for preventive maintenance planning. Although FMEA was studied extensively, most of the published work so far covers FMEA concept design. Lit

  4. Root cause analysis of pump valve failures of three membrane pump systems

    NARCIS (Netherlands)

    Buijs, L.J.; Eijk, A.; Hooft, L. van

    2014-01-01

    This paper will present the root cause analysis and the solution of fatigue failures of the pump valves of three membrane pump systems installed on a chemical plant of Momentive in Pernis, the Netherlands. The membrane pumps were installed approximately 30 years ago. Each system has encountered fati

  5. Common-Cause Failure Analysis for Reactor Protection System Reliability Studies

    Energy Technology Data Exchange (ETDEWEB)

    Gentillon, C.; Rasmuson, D.; Eide, S.; Wierman, T.

    1999-08-01

    Analyses were performed of the safety-related performance of the reactor protection system (RPS) at U.S. Westinghouse and General Electric commercial reactors during the period 1984 through 1995. RPS operational data from these reactors were collected from the Nuclear Plant Reliability Data System (NPRDS) and Licensee Event Reports (LER). The common-cause failure (CCF) modeling in the fault trees developed for these studies and the analysis and use of common-cause failure data were sophisticated, state-of-the-art efforts. The overall CCF effort helped to test and expand the limits of the U.S. Nuclear Regulatory Commission's CCF methodology.

  6. A COCAP program for the statistical analysis of common cause failure parameters

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Baehyeuk; Jae, Moosung [Hanyang Univ., Seoul (Korea, Republic of). Dept. of Nuclear Engineering

    2016-03-15

    Probabilistic Safety Assessment (PSA) based applications and regulations are becoming more important in the field of nuclear energy. According to the results of a PSA in Korea, the common cause failure evaluates CDF (Core Damage Frequency) as one of the significant factors affecting redundancy of NPPs. The purpose of the study is to develop a COCAP (Common Cause Failure parameter Analysis for PSA) program for the accurate use of the alpha factor model parameter data provided by other countries and for obtaining the indigenous CCF data of NPPs in Korea through Bayesian updating.

  7. Failure Modes and Effects Analysis (FMEA) of the Residual Heat Removal System. [PWR

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Ship operation and failure mode analysis using a maneuver simulator

    Science.gov (United States)

    Cabrerizo-Morales, Miguel Angel; Molina, Rafael; de los Santos, Francisco; Camarero, Alberto

    2013-04-01

    In a ship or floating structure operation the agents that contribute to the systems behaviour are not only those derived from fluid-structure interaction, but also the ones linked to mooring-control line set-up evolution and human interaction. Therefore, the analysis of such systems is affected by boundary conditions that change during a complete operation. Frequently, monitoring techniques in laboratory (model) and field (prototype) are based in different instrumental techniques adding difficulty to data comparison and, in some cases, inducing precision and repeatability errors. For this reason, the main aim of this study is to develop the methods and tools to achieve a deep knowledge of those floating systems and obtain capabilities to optimize their operationally thresholds. This abstract presents a methodology and an instrumental system applicable both in field and laboratory: SRECMOCOS Project (Small scale REal-time Caisson MOnitoring and COntrol System). SRECMOCOS compiles three modules. For the monitoring and control of the structure it has been developed a synchronized open and modular microcontroller-based electronic system that comprises sensors, to monitor agents and reactions, and actuators to perform pertinent actions after processing the sensors' data. A secondary objective has been to design and implement a global scaled simulator (1:22), at the 3D basin of The Harbour Research Lab at Technical University of Madrid, in which climatic agents and those derived from the rig/maneuvering setup and the structural design were included. The particular case of Campamento's drydock, in Algeciras Bay (Spain), has been used to apply and validate the methodology. SRECMOCOS Project conjugates control, monitoring and wireless communication systems in a real time basis, offering the possibility to register and simulate all the parameters involved in port operations. This approach offers a step forward into a monitoring strategy to be included in monitoring

  9. Phase Field Theory and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic

    Science.gov (United States)

    2014-08-01

    Phase Field Theory and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic by John D Clayton ARL-RP...Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic John D Clayton Weapons and Materials Research Directorate, ARL...and Analysis of Pressure-Shear Induced Amorphization and Failure in Boron Carbide Ceramic 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM

  10. Bruxism and dental implant failures: a multilevel mixed effects parametric survival analysis approach.

    Science.gov (United States)

    Chrcanovic, B R; Kisch, J; Albrektsson, T; Wennerberg, A

    2016-11-01

    Recent studies have suggested that the insertion of dental implants in patients being diagnosed with bruxism negatively affected the implant failure rates. The aim of the present study was to investigate the association between the bruxism and the risk of dental implant failure. This retrospective study is based on 2670 patients who received 10 096 implants at one specialist clinic. Implant- and patient-related data were collected. Descriptive statistics were used to describe the patients and implants. Multilevel mixed effects parametric survival analysis was used to test the association between bruxism and risk of implant failure adjusting for several potential confounders. Criteria from a recent international consensus (Lobbezoo et al., J Oral Rehabil, 40, 2013, 2) and from the International Classification of Sleep Disorders (International classification of sleep disorders, revised: diagnostic and coding manual, American Academy of Sleep Medicine, Chicago, 2014) were used to define and diagnose the condition. The number of implants with information available for all variables totalled 3549, placed in 994 patients, with 179 implants reported as failures. The implant failure rates were 13·0% (24/185) for bruxers and 4·6% (155/3364) for non-bruxers (P < 0·001). The statistical model showed that bruxism was a statistically significantly risk factor to implant failure (HR 3·396; 95% CI 1·314, 8·777; P = 0·012), as well as implant length, implant diameter, implant surface, bone quantity D in relation to quantity A, bone quality 4 in relation to quality 1 (Lekholm and Zarb classification), smoking and the intake of proton pump inhibitors. It is suggested that the bruxism may be associated with an increased risk of dental implant failure.

  11. Failure mode and effect analysis-based quality assurance for dynamic MLC tracking systems

    Energy Technology Data Exchange (ETDEWEB)

    Sawant, Amit; Dieterich, Sonja; Svatos, Michelle; Keall, Paul [Stanford University, Stanford, California 94394 (United States); Varian Medical Systems, Palo Alto, California 94304 (United States); Stanford University, Stanford, California 94394 (United States)

    2010-12-15

    Purpose: To develop and implement a failure mode and effect analysis (FMEA)-based commissioning and quality assurance framework for dynamic multileaf collimator (DMLC) tumor tracking systems. Methods: A systematic failure mode and effect analysis was performed for a prototype real-time tumor tracking system that uses implanted electromagnetic transponders for tumor position monitoring and a DMLC for real-time beam adaptation. A detailed process tree of DMLC tracking delivery was created and potential tracking-specific failure modes were identified. For each failure mode, a risk probability number (RPN) was calculated from the product of the probability of occurrence, the severity of effect, and the detectibility of the failure. Based on the insights obtained from the FMEA, commissioning and QA procedures were developed to check (i) the accuracy of coordinate system transformation, (ii) system latency, (iii) spatial and dosimetric delivery accuracy, (iv) delivery efficiency, and (v) accuracy and consistency of system response to error conditions. The frequency of testing for each failure mode was determined from the RPN value. Results: Failures modes with RPN{>=}125 were recommended to be tested monthly. Failure modes with RPN<125 were assigned to be tested during comprehensive evaluations, e.g., during commissioning, annual quality assurance, and after major software/hardware upgrades. System latency was determined to be {approx}193 ms. The system showed consistent and accurate response to erroneous conditions. Tracking accuracy was within 3%-3 mm gamma (100% pass rate) for sinusoidal as well as a wide variety of patient-derived respiratory motions. The total time taken for monthly QA was {approx}35 min, while that taken for comprehensive testing was {approx}3.5 h. Conclusions: FMEA proved to be a powerful and flexible tool to develop and implement a quality management (QM) framework for DMLC tracking. The authors conclude that the use of FMEA-based QM ensures

  12. Analysis of potential failure modes and failure mechanisms in spacecrafts%航天机构潜在故障模式与故障机理分析

    Institute of Scientific and Technical Information of China (English)

    马明臻; 张新宇; 谭春林; 刘日平

    2014-01-01

    空间环境效应、制造加工质量以及所承受的工作载荷是诱发航天机构在轨服役过程中潜在故障的影响因素,对其服役寿命和可靠性将产生重要的影响。因此,开展航天机构潜在故障模式与故障机理分析具有重要科学意义和工程价值。本文对航天机构潜在故障的成因、故障模式、故障机理与影响因素之间的关系以及故障的种类进行了论述,梳理了3类15种可能引发航天机构潜在故障的因素,指出由润滑失效引起的摩擦磨损和载荷作用引起的疲劳失效是导致航天机构潜在故障的两个重要原因,并提出了故障机理的分析程序和方法。%The factors for potential failures in spacecrafts include the effects of the harsh space environment on it during the on-orbit servicing, manufacturing quality as well as the work load during service, which all have significant impacts on its service life and reliability. Therefore, it is of great scientific and technical importance to analyze potential failure mechanism and failure modes in the spacecrafts. In this paper, the types of failures and the relationship of the causes of potential failures, failure modes, failure mechanism and influencing factors for a space structure are discussed. Additionally, fifteen factors classified as three categories that could lead to potential failures of the spacecrafts are presented. It is concluded that the friction and wear phenomena resulted from lubrication failure and fatigue failure related to the loading are two major potential causes of failure in space structure. Pro-cedures and strategies for the analysis of failure mechanism are proposed.

  13. Low Carbon-Oriented Optimal Reliability Design with Interval Product Failure Analysis and Grey Correlation Analysis

    Directory of Open Access Journals (Sweden)

    Yixiong Feng

    2017-03-01

    Full Text Available The problem of large amounts of carbon emissions causes wide concern across the world, and it has become a serious threat to the sustainable development of the manufacturing industry. The intensive research into technologies and methodologies for green product design has significant theoretical meaning and practical value in reducing the emissions of the manufacturing industry. Therefore, a low carbon-oriented product reliability optimal design model is proposed in this paper: (1 The related expert evaluation information was prepared in interval numbers; (2 An improved product failure analysis considering the uncertain carbon emissions of the subsystem was performed to obtain the subsystem weight taking the carbon emissions into consideration. The interval grey correlation analysis was conducted to obtain the subsystem weight taking the uncertain correlations inside the product into consideration. Using the above two kinds of subsystem weights and different caution indicators of the decision maker, a series of product reliability design schemes is available; (3 The interval-valued intuitionistic fuzzy sets (IVIFSs were employed to select the optimal reliability and optimal design scheme based on three attributes, namely, low carbon, correlation and functions, and economic cost. The case study of a vertical CNC lathe proves the superiority and rationality of the proposed method.

  14. Using pattern analysis methods to do fast detection of manufacturing pattern failures

    Science.gov (United States)

    Zhao, Evan; Wang, Jessie; Sun, Mason; Wang, Jeff; Zhang, Yifan; Sweis, Jason; Lai, Ya-Chieh; Ding, Hua

    2016-03-01

    At the advanced technology node, logic design has become extremely complex and is getting more challenging as the pattern geometry size decreases. The small sizes of layout patterns are becoming very sensitive to process variations. Meanwhile, the high pressure of yield ramp is always there due to time-to-market competition. The company that achieves patterning maturity earlier than others will have a great advantage and a better chance to realize maximum profit margins. For debugging silicon failures, DFT diagnostics can identify which nets or cells caused the yield loss. But normally, a long time period is needed with many resources to identify which failures are due to one common layout pattern or structure. This paper will present a new yield diagnostic flow, based on preliminary EFA results, to show how pattern analysis can more efficiently detect pattern related systematic defects. Increased visibility on design pattern related failures also allows more precise yield loss estimation.

  15. A generalized rough set-based information filling technique for failure analysis of thruster experimental data

    Institute of Scientific and Technical Information of China (English)

    Han Shan; Zhu Qiang; Li Jianxun; Chen Lin

    2013-01-01

    Interval-valued data and incomplete data are two key problems for failure analysis of thruster experimental data and have been basically solved by the proposed methods in this paper. Firstly, information data acquired from the simulation and evaluation system formed as interval-valued information system (IIS) is classified by the interval similarity relation. Then, as an improve-ment of the classical rough set, a new kind of generalized information entropy called‘‘H0-informa-tion entropy’’ is suggested for the measurement of uncertainty and the classification ability of IIS. There is an innovative information filling technique using the properties of H0-information entropy to replace missing data by some smaller estimation intervals. Finally, an improved method of failure analysis synthesized by the above achievements is presented to classify the thruster experimental data, complete the information, and extract the failure rules. The feasibility and advantage of this method is testified by an actual application of failure analysis, whose performance is evaluated by the quantification of E-condition entropy.

  16. Continuum Damage Mechanics Models for the Analysis of Progressive Failure in Open-Hole Tension Laminates

    Science.gov (United States)

    Song, Kyonchan; Li, Yingyong; Rose, Cheryl A.

    2011-01-01

    The performance of a state-of-the-art continuum damage mechanics model for interlaminar damage, coupled with a cohesive zone model for delamination is examined for failure prediction of quasi-isotropic open-hole tension laminates. Limitations of continuum representations of intra-ply damage and the effect of mesh orientation on the analysis predictions are discussed. It is shown that accurate prediction of matrix crack paths and stress redistribution after cracking requires a mesh aligned with the fiber orientation. Based on these results, an aligned mesh is proposed for analysis of the open-hole tension specimens consisting of different meshes within the individual plies, such that the element edges are aligned with the ply fiber direction. The modeling approach is assessed by comparison of analysis predictions to experimental data for specimen configurations in which failure is dominated by complex interactions between matrix cracks and delaminations. It is shown that the different failure mechanisms observed in the tests are well predicted. In addition, the modeling approach is demonstrated to predict proper trends in the effect of scaling on strength and failure mechanisms of quasi-isotropic open-hole tension laminates.

  17. Analysis of seismic disaster failure mechanism and dam-break simulation of high arch dam

    Science.gov (United States)

    Zhang, Jingkui; Zhang, Liaojun

    2014-06-01

    Based on a Chinese national high arch dam located in a meizoseismal region, a nonlinear numerical analysis model of the damage and failure process of a dam-foundation system is established by employing a 3-D deformable distinct element code (3DEC) and its re-development functions. The proposed analysis model considers the dam-foundation-reservoir coupling effect, influence of nonlinear contact in the opening and closing of the dam seam surface and abutment rock joints during strong earthquakes, and radiation damping of far field energy dissipation according to the actual workability state of an arch dam. A safety assessment method and safety evaluation criteria is developed to better understand the arch dam system disaster process from local damage to ultimate failure. The dynamic characteristics, disaster mechanism, limit bearing capacity and the entire failure process of a high arch dam under a strong earthquake are then analyzed. Further, the seismic safety of the arch dam is evaluated according to the proposed evaluation criteria and safety assessment method. As a result, some useful conclusions are obtained for some aspects of the disaster mechanism and failure process of an arch dam. The analysis method and conclusions may be useful in engineering practice.

  18. Analysis of micro-failure behaviors in artificial muscles based on fishing line and sewing thread

    Science.gov (United States)

    Xu, J. B.; Cheng, K. F.; Tu, S. L.; He, X. M.; Ma, C.; Jin, Y. Z.; Kang, X. N.; Sun, T.; Zhang, Y.

    2017-06-01

    The aim of the present study was to discuss a new and effective method for testing artificial muscles based on micro-failure behaviors analysis. Thermo-mechanical actuators based on fishing line and sewing thread, also, the capability of responding to ambient temperature variations producing a large amount of shrinkage ratio of a resulting variation in longitudinal length. The minimum micro-failure value is 0.02μm and the maximum value is 1.72μm with nylon twist pattern. The discovery of an innovative effective testing of artificial muscles based on polymeric fibers specimens on micro-failure, rupture, slippage, etc. This research finds out a micro-failure behavior analysis of thermo-mechanical actuators based on fishing line and sewing thread. The specimens show large deformations when heated together with warping performance in terms of shrinkage of energy and densities. With the purpose of providing useful analysis data for the further technology applications, we attempt micrometre-sized artificial muscles which were also tested was readily accessible and also can be applied to other polymeric fibers. Effective use of this technique achievement relies on rotate speed, temperature and tensile direction. The results of the tensile testing experiments were outstanding with respect to some important issues related to the response of micro-structure, twisted polymeric fibers and shrinkage ratio.

  19. Reliability Analysis of Fatigue Failure of Cast Components for Wind Turbines

    Directory of Open Access Journals (Sweden)

    Hesam Mirzaei Rafsanjani

    2015-04-01

    Full Text Available Fatigue failure is one of the main failure modes for wind turbine drivetrain components made of cast iron. The wind turbine drivetrain consists of a variety of heavily loaded components, like the main shaft, the main bearings, the gearbox and the generator. The failure of each component will lead to substantial economic losses such as cost of lost energy production and cost of repairs. During the design lifetime, the drivetrain components are exposed to variable loads from winds and waves and other sources of loads that are uncertain and have to be modeled as stochastic variables. The types of loads are different for offshore and onshore wind turbines. Moreover, uncertainties about the fatigue strength play an important role in modeling and assessment of the reliability of the components. In this paper, a generic stochastic model for fatigue failure of cast iron components based on fatigue test data and a limit state equation for fatigue failure based on the SN-curve approach and Miner’s rule is presented. The statistical analysis of the fatigue data is performed using the Maximum Likelihood Method which also gives an estimate of the statistical uncertainties. Finally, illustrative examples are presented with reliability analyses depending on various stochastic models and partial safety factors.

  20. Copula-Based Slope Reliability Analysis Using the Failure Domain Defined by the g-Line

    Directory of Open Access Journals (Sweden)

    Xiaoliang Xu

    2016-01-01

    Full Text Available The estimation of the cross-correlation of shear strength parameters (i.e., cohesion and internal friction angle and the subsequent determination of the probability of failure have long been challenges in slope reliability analysis. Here, a copula-based approach is proposed to calculate the probability of failure by integrating the copula-based joint probability density function (PDF on the slope failure domain delimited with the g-line. Here, copulas are used to construct the joint PDF of shear strength parameters with specific marginal distributions and correlation structure. In the paper a failure (limit state function approach is applied to investigate a system characterized by a homogeneous slope. The results show that the values obtained by using the failure function approach are similar to those calculated by means of conventional methods, such as the first-order reliability method (FORM and Monte Carlo simulations (MC. In addition, an entropy weight (EW copula is proposed to address the discrepancies of the results calculated by different copulas to avoid over- or underestimating the slope reliability.

  1. Analysis of Noise Failure Characteristics for Superluminescent Diode Fiber-Optic Gyroscopes in Space Applications

    Science.gov (United States)

    Li, Min; Huang, Xiaokai; Jin, Jing; Chen, Yunxia; Kang, Rui

    Noise failure, particularly due to random walk error (RWE) degradation behavior, is one of the critical failure modes for fiber-optic gyroscopes (FOGs) in space applications. In this paper, firstly, the analytical model of RWE is presented and the affected parameters are listed according to the gamma irradiation damage mechanism. In addition, the influence of temperature is also included. The deterioration of affected parameters is determined through a 60Co radiation experiment on optic and optoelectronic components. Based on the parameters’ deterioration range and assumed distribution properties, their importance to the noise failure is calculated through the Sobol method, a global sensitivity analysis method. In the computation steps, the Latin Hyper Sampling (LHS) based Monte-Carlo numerical simulation technique is adopted. It is determined from calculation results that the detected light power (DLP) is the noise failure characteristic which is the most sensitive parameter in the space environment. Finally, another 60Co radiation experiment with the same conditions is performed on a superluminescent diode (SLD) FOG. The original noise degradation behavior is compared to the simulated RWE, calculated according to DLP, and the result shows that they follow trend almost identical. This supports the conclusion that DLP is the most sensitive noise failure characteristic for SLD-based FOGs.

  2. Abnormal Failure Analysis of H13 Punches in Steel Squeeze Casting Process

    Institute of Scientific and Technical Information of China (English)

    ZHANG Mi-lan; XING Shu-ming; XIN Qiao; XIAO Li-ming; GOU Jun-nian; WU Xia-ling

    2008-01-01

    In steel squeeze casting process, the working condition of a punch was very rigorous. The abnormal failure models of an H13 punch, such as plastic rubbed damnification, could not be avoided easily. Based on the analysis of the flow stress and the friction-shearing stress of an H13 punch in steel squeeze casting process, the following results were obtained: if the flow stress of an H13 punch was smaller than its friction-shearing stress, these abnormal failures could not be avoided; and if there were some protection measures that enable the flow stress to have a greater value than its friction-shearing one, the abnormal failures would not occur. In the production of 45# steel valves and eatenary system components, the flow stress of a lateral H13 punch without any protection measure was about 29 MPa and its friction-shearing stress.was about 51 MPa, then, the abnormal failures occurred: however, when the protection measures of the punch enabled its working temperature to have a value below 682 "C, its flow stress was greater than its friction-shearing stress, and the abnormal failures were avoided.

  3. Failure mode effect analysis applied to the use of infusion pumps.

    Science.gov (United States)

    Fechter, Richard J; Barba, Julio J

    2004-01-01

    Failure Mode Effect Analysis (FMEA) offers a prospective approach to reducing the risk associated with health care delivery. Beginning in February, 2002, an interdisciplinary team of fifteen individuals, including end-users, conducted an FMEA for the use of infusion pumps at UCSF Medical Center. The use of infusion pumps was identified as the area of highest risk, based on incident report data. The team identified sixteen potential failure modes, including their potential effects and causes, and assigned a risk priority number to each based on the potential severity, probability, and detectability of the failure. Notable failure modes included: incorrect programming; improper or inconsistent labeling of solution, tubing, and pump; potential use of malfunctioning or damaged pumps; and incorrect programming by nurses related to device design. The team then broke into smaller work groups and invited more end-users to perform root cause analyses and suggest recommended actions/outcome measures for each failure mode with a risk priority number of 32 or higher (on our scale of 1 to 64). Finally, the FMEA team assembled all of the data, prepared a final report, and assigned responsibility for key recommended actions.

  4. Stress and Failure Analysis of Rapidly Rotating Asteroid (29075) 1950 DA

    CERN Document Server

    Hirabayashi, Masatoshi

    2014-01-01

    Rozitis et al. recently reported that near-Earth asteroid (29075) 1950 DA, whose bulk density ranges from 1.0 g/cm3 to 2.4 g/cm3, is a rubble pile and requires a cohesive strength of at least 44 Pa to 74 Pa to keep from failing due to its fast spin period. Since their technique for giving failure conditions required the averaged stress over the whole volume, it discarded information about the asteroid's failure mode and internal stress condition. This paper develops a finite element model and revisits the stress and failure analysis of 1950 DA. For the modeling, we do not consider material-hardening and softening. Under the assumption of an associated flow rule and uniform material distribution, we identify the deformation process of 1950 DA when its constant cohesion reaches the lowest value that keeps its current shape. The results show that to avoid structural failure the internal core requires a cohesive strength of at least 75 Pa - 85 Pa. It suggests that for the failure mode of this body, the internal c...

  5. Evaluating the operational risks of biomedical waste using failure mode and effects analysis.

    Science.gov (United States)

    Chen, Ying-Chu; Tsai, Pei-Yi

    2017-06-01

    The potential problems and risks of biomedical waste generation have become increasingly apparent in recent years. This study applied a failure mode and effects analysis to evaluate the operational problems and risks of biomedical waste. The microbiological contamination of biomedical waste seldom receives the attention of researchers. In this study, the biomedical waste lifecycle was divided into seven processes: Production, classification, packaging, sterilisation, weighing, storage, and transportation. Twenty main failure modes were identified in these phases and risks were assessed based on their risk priority numbers. The failure modes in the production phase accounted for the highest proportion of the risk priority number score (27.7%). In the packaging phase, the failure mode 'sharp articles not placed in solid containers' had the highest risk priority number score, mainly owing to its high severity rating. The sterilisation process is the main difference in the treatment of infectious and non-infectious biomedical waste. The failure modes in the sterilisation phase were mainly owing to human factors (mostly related to operators). This study increases the understanding of the potential problems and risks associated with biomedical waste, thereby increasing awareness of how to improve the management of biomedical waste to better protect workers, the public, and the environment.

  6. Summary and analysis of 216 GHz polarimetric measurements of in-situ rain

    Science.gov (United States)

    Hedden, Abigail S.; Wikner, David A.; Bradley, Russell W.

    2015-05-01

    The Army Research Laboratory (ARL) has developed a polarimetric frequency-modulated continuous-wave (FMCW) instrumentation radar that has been used to study the polarization and backscatter properties of in-situ rain in the 220 GHz atmospheric window. A summary of the preliminary measurements is presented in this work including an analysis of the co-polarization backscatter and attenuation characteristics measured at 216 GHz. A marginal detection of the copolarization backscatter signature of rain was made during a series of fast-moving, heavy downpour thunderstorm events. A detection limit of -40±3 dB[m2/m3] was found for the VV-polarization cross section per unit volume for rain rates up to 150 mm/hr. Co-polarization (VV- and HH-polarization) attenuation characteristics measured at high rain rates (< 20 mm/hr) were well described by a Joss thunderstorm drop distribution in the high frequency limit, where drop size is much greater than the observation wavelength. Observations at 216 GHz suggest attenuation levels of 8-10 dB/km at rain rates above 20 mm/hr, strengthening previous evidence that attenuation through rain is independent of frequency under high rain rate conditions. Attenuation measurements at lower rain rates (< 20 mm/hr) were qualitatively consistent with both Laws and Parsons and Joss thunderstorm distributions.

  7. Material wear and failure mode analysis of breakfast cereal extruder barrels and screw elements

    Science.gov (United States)

    Mastio, Michael Joseph, Jr.

    2005-11-01

    Nearly seventy-five years ago, the single screw extruder was introduced as a means to produce metal products. Shortly after that, the extruder found its way into the plastics industry. Today much of the world's polymer industry utilizes extruders to produce items such as soda bottles, PVC piping, and toy figurines. Given the significant economical advantages of extruders over conventional batch flow systems, extruders have also migrated into the food industry. Food applications include the meat, pet food, and cereal industries to name just a few. Cereal manufacturers utilize extruders to produce various forms of Ready-to-Eat (RTE) cereals. These cereals are made from grains such as rice, oats, wheat, and corn. The food industry has been incorrectly viewed as an extruder application requiring only minimal energy control and performance capability. This misconception has resulted in very little research in the area of material wear and failure mode analysis of breakfast cereal extruders. Breakfast cereal extruder barrels and individual screw elements are subjected to the extreme pressures and temperatures required to shear and cook the cereal ingredients, resulting in excessive material wear and catastrophic failure of these components. Therefore, this project focuses on the material wear and failure mode analysis of breakfast cereal extruder barrels and screw elements, modeled as a Discrete Time Markov Chain (DTMC) process in which historical data is used to predict future failures. Such predictive analysis will yield cost savings opportunities by providing insight into extruder maintenance scheduling and interchangeability of screw elements. In this DTMC wear analysis, four states of wear are defined and a probability transition matrix is determined based upon 24,041 hours of operational data. This probability transition matrix is used to predict when an extruder component will move to the next state of wear and/or failure. This information can be used to determine

  8. Theory and analysis of nonlinear dynamics and stability in storage rings: A working group summary

    Energy Technology Data Exchange (ETDEWEB)

    Chattopadhyay, S.; Audy, P.; Courant, E.D.; Forest, E.; Guignard, G.; Hagel, J.; Heifets, S.; Keil, E.; Kheifets, S.; Mais, H.; Moshammer, H.; Pellegrini, C.; Pilat, F.; Suzuki, T.; Turchetti, G.; Warnock, R.L.

    1988-07-01

    A summary and commentary of the available theoretical and analytical tools and recent advances in the nonlinear dynamics, stability and aperture issues in storage rings are presented. 11 refs., 4 figs.

  9. Theoretical and experimental analysis of inverter fed induction motor system under DC link capacitor failure

    Directory of Open Access Journals (Sweden)

    Hadeed A. Sher

    2017-04-01

    Full Text Available In this paper theoretical and experimental analysis of an AC–DC–AC inverter under DC link capacitor failure is presented. The failure study conducted for this paper is the open circuit of the DC link capacitor. The presented analysis incorporates the results for both single and three phase AC input. It has been observed that the higher ripple frequency provides better ride through capability for this fault. Furthermore, the effects of this fault on electrical characteristics of AC–DC–AC inverter and mechanical properties of the induction motor are also presented. Moreover, the effect of pulsating torque as a result of an open circuited DC link capacitor is also taken into consideration. Theoretical analysis is supported by computer aided simulation as well as with a real time experimental prototype.

  10. Post-test creep analysis of piping failure tests in wind project

    Energy Technology Data Exchange (ETDEWEB)

    Chino, E.; Maruyama, Y.; Yuchi, Y.; Shibazaki, H.; Nakamura, H.; Hidaka, A.; Kudo, T.; Hashimoto, K. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Maeda, A. [Applied and Scientific Systems Department, MRI Systems Inc., Tokyo (Japan)

    2000-11-01

    Thermal and structural responses of the reactor coolant piping under elevated temperature and pressure conditions are being investigated in piping failure tests in WIND (Wide Range Piping Integrity Demonstration) project at JAERI (Japan Atomic Energy Research Institute). The elasto-plastic creep analysis was performed with ABAQUS code for the test using a nuclear grade type 316 stainless steel pipe, which had an outer diameter of 114.3 mm and a wall thickness of 13.5 mm. The major material properties at elevated temperature needed for the analysis were measured for specimen sectioned from the test pipe. Based on the measured creep data, a creep constitutive equation including the tertiary stage was developed and incorporated into ABAQUS code. We compared the results of the three-dimensional analysis with those of two-dimensional analysis and the piping failure test. The comparison showed that the piping failure timing and deformation of pipe obtained from the three dimensional analysis underestimated the test results, and that temperature history at the elevated temperature should be adequately considered. (author)

  11. A Framework for Performing Multiscale Stochastic Progressive Failure Analysis of Composite Structures

    Science.gov (United States)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2007-01-01

    A framework is presented that enables coupled multiscale analysis of composite structures. The recently developed, free, Finite Element Analysis-Micromechanics Analysis Code (FEAMAC) software couples the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC) with ABAQUS to perform micromechanics based FEA such that the nonlinear composite material response at each integration point is modeled at each increment by MAC/GMC. As a result, the stochastic nature of fiber breakage in composites can be simulated through incorporation of an appropriate damage and failure model that operates within MAC/GMC on the level of the fiber. Results are presented for the progressive failure analysis of a titanium matrix composite tensile specimen that illustrate the power and utility of the framework and address the techniques needed to model the statistical nature of the problem properly. In particular, it is shown that incorporating fiber strength randomness on multiple scales improves the quality of the simulation by enabling failure at locations other than those associated with structural level stress risers.

  12. An investigation into failure analysis of interfering part of a steam turbine journal bearing

    Directory of Open Access Journals (Sweden)

    M. Mehdizadeh

    2014-10-01

    Full Text Available Journal bearings as so sensitive parts of steam turbines are very susceptible to failure through different mechanisms of wear, fatigue and crush during service conditions. Failure occurring through these mechanisms lead to turbine completely shut down as a result of interfering in working conditions of bearing different parts. In this research, failed interfered part of a journal bearing related to a 320,000 kW steam turbine was examined. Failure analysis investigations were performed by utilizing of stereographic, optical microscopy, scanning electron microscopy (SEM, energy-dispersive X-ray spectroscopy (EDS analysis and hardness test. Surface crush, large amounts of surface cracks, no noticeable changes of failed surface chemical composition and microstructure with significant hardness improvement were the main obtained results. The studies were revealed that the bearing part loosing and inappropriate clearance can produce relative displacements under cyclic gradient loading. This condition was detrimental for the service life of turbine journal bearing via failure through fretting fatigue mechanism.

  13. Failure mode and effects analysis using intuitionistic fuzzy hybrid weighted Euclidean distance operator

    Science.gov (United States)

    Liu, Hu-Chen; Liu, Long; Li, Ping

    2014-10-01

    Failure mode and effects analysis (FMEA) has shown its effectiveness in examining potential failures in products, process, designs or services and has been extensively used for safety and reliability analysis in a wide range of industries. However, its approach to prioritise failure modes through a crisp risk priority number (RPN) has been criticised as having several shortcomings. The aim of this paper is to develop an efficient and comprehensive risk assessment methodology using intuitionistic fuzzy hybrid weighted Euclidean distance (IFHWED) operator to overcome the limitations and improve the effectiveness of the traditional FMEA. The diversified and uncertain assessments given by FMEA team members are treated as linguistic terms expressed in intuitionistic fuzzy numbers (IFNs). Intuitionistic fuzzy weighted averaging (IFWA) operator is used to aggregate the FMEA team members' individual assessments into a group assessment. IFHWED operator is applied thereafter to the prioritisation and selection of failure modes. Particularly, both subjective and objective weights of risk factors are considered during the risk evaluation process. A numerical example for risk assessment is given to illustrate the proposed method finally.

  14. BILAM: a composite laminate failure-analysis code using bilinear stress-strain approximations

    Energy Technology Data Exchange (ETDEWEB)

    McLaughlin, P.V. Jr.; Dasgupta, A.; Chun, Y.W.

    1980-10-01

    The BILAM code which uses constant strain laminate analysis to generate in-plane load/deformation or stress/strain history of composite laminates to the point of laminate failure is described. The program uses bilinear stress-strain curves to model layer stress-strain behavior. Composite laminates are used for flywheels. The use of this computer code will help to develop data on the behavior of fiber composite materials which can be used by flywheel designers. In this program the stress-strain curves are modelled by assuming linear response in axial tension while using bilinear approximations (2 linear segments) for stress-strain response to axial compressive, transverse tensile, transverse compressive and axial shear loadings. It should be noted that the program attempts to empirically simulate the effects of the phenomena which cause nonlinear stress-strain behavior, instead of mathematically modelling the micromechanics involved. This code, therefore, performs a bilinear laminate analysis, and, in conjunction with several user-defined failure interaction criteria, is designed to provide sequential information on all layer failures up to and including the first fiber failure. The modus operandi is described. Code BILAM can be used to: predict the load-deformation/stress-strain behavior of a composite laminate subjected to a given combination of in-plane loads, and make analytical predictions of laminate strength.

  15. Primary failure of eruption (PFE)--clinical and molecular genetics analysis.

    Science.gov (United States)

    Stellzig-Eisenhauer, Angelika; Decker, Eva; Meyer-Marcotty, Philipp; Rau, Christiane; Fiebig, Britta S; Kress, Wolfram; Saar, Kathrin; Rüschendorf, Franz; Hubner, Norbert; Grimm, Tiemo; Witt, Emil; Weber, Bernhard H F

    2010-01-01

    The term "primary failure of eruption" (PFE) refers to the complete or partial failure of a primary non-ankylosed tooth to erupt due to a disturbance of the eruption mechanism. Up to now, the molecular basis for this failure was unknown. Four families were studied in whom at least two members were affected by non-syndromic PFE as part of a clinical and molecular genetics study. Radiological diagnostics (OPTs) were carried out in all patients and their unaffected relatives (control group). The genetic analysis included a genomewide linkage analysis followed by direct DNA sequencing of positional candidate genes. Starting from the index patients, we were able to reconstruct pedigrees over two and/or three generations in the families that indicated an autosomal-dominant mode of inheritance of non-syndromic PFE. Fifteen patients were diagnosed with PFE. Gender distribution was nearly equal (7 female, 8 male). Molecular genetic analysis of the PTHR1 gene revealed three distinct heterozygous mutations (c.1050-3C>G; c.543+1G>A; c.463G>T). Unaffected persons exhibited no mutations. Knowledge of the genetic causes of non-syndromic PFE can now be used for the differential diagnosis of eruption failure. It permits affected family members to be identified early and may lead to new treatment possibilities in the long term. The genetically-verified diagnosis of "primary failure of eruption" can protect patients and orthodontists from years of futile treatment, because orthodontic treatment alone does not lead to success. Moreover, it has a negative influence on unaffected teeth and areas of the jaw.

  16. Effects of a Gluten-Free Diet on Rate of Learning in Autistic Children in an Applied Behavioral Analysis Program: Summary Analysis.

    Science.gov (United States)

    Pontino, Jamie Lyn; Schaal, Kelly; Chambliss, Catherine

    This summary analysis discusses a series of studies that used both between-subjects and within-subjects analyses to examine the effects of a gluten-free diet on the academic achievement of children with autism. In the first study, the between-subjects analysis included data from eight children with autism (ages 5-7), with four on a gluten-free…

  17. Identification of Modeling Approaches To Support Common-Cause Failure Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Korsah, Kofi [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wood, Richard Thomas [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-06-01

    Experience with applying current guidance and practices for common-cause failure (CCF) mitigation to digital instrumentation and control (I&C) systems has proven problematic, and the regulatory environment has been unpredictable. The impact of CCF vulnerability is to inhibit I&C modernization and, thereby, challenge the long-term sustainability of existing plants. For new plants and advanced reactor concepts, the issue of CCF vulnerability for highly integrated digital I&C systems imposes a design burden resulting in higher costs and increased complexity. The regulatory uncertainty regarding which mitigation strategies are acceptable (e.g., what diversity is needed and how much is sufficient) drives designers to adopt complicated, costly solutions devised for existing plants. The conditions that constrain the transition to digital I&C technology by the U.S. nuclear industry require crosscutting research to resolve uncertainty, demonstrate necessary characteristics, and establish an objective basis for qualification of digital technology for usage in Nuclear Power Plant (NPP) I&C applications. To fulfill this research need, Oak Ridge National Laboratory is conducting an investigation into mitigation of CCF vulnerability for nuclear-qualified applications. The outcome of this research is expected to contribute to a fundamentally sound, comprehensive technical basis for establishing the qualification of digital technology for nuclear power applications. This report documents the investigation of modeling approaches for representing failure of I&C systems. Failure models are used when there is a need to analyze how the probability of success (or failure) of a system depends on the success (or failure) of individual elements. If these failure models are extensible to represent CCF, then they can be employed to support analysis of CCF vulnerabilities and mitigation strategies. Specifically, the research findings documented in this report identify modeling approaches that

  18. Membrane dish analysis: A summary of structural and optical analysis capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Steele, C.R.; Balch, C.D.; Jorgensen, G.J.; Wendelin, T.; Lewandowski, A.

    1991-11-01

    Research at SERI within the Department of Energy's Solar Thermal Technology Program has focused on the development of membrane dish concentrators for space and terrestrial power applications. As potentially lightweight, inexpensive, high-performance structures, they are excellent candidates for space-deployable energy sources as well as cost-effective terrestrial energy concepts. A thorough engineering research treatment of these types of structures consists primarily of two parts: (1) structural mechanics of the membrane and ring support and (2) analysis and characterization of the concentrator optical performance. It is important to understand the effects of the membrane's structure and support system on the optical performance of the concentrator. This requires an interface between appropriate structural and optical models. Until recently, such models and the required interface have not existed. This report documents research that has been conducted at SERI in this area. It is a compilation of several papers describing structural models of membrane dish structures and optical models used to predict dish concentrator optical and thermal performance. The structural models were developed under SERI subcontract by Dr. Steele and Dr. Balch of Stanford University. The optical model was developed in-house by SERI staff. In addition, the interface between the models is described. It allows easy and thorough characterization of membrane dish systems from the mechanics to the resulting optical performance. The models described herein have been and continue to be extremely useful to SERI, industry, and universities involved with the modeling and analysis of lightweight membrane concentrators for solar thermal applications.

  19. 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

    BACKGROUND: 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. METHODS: 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. RESULTS: 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. CONCLUSION: “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”,

  20. Membrane dish analysis: A summary of structural and optical analysis capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Steele, C.R.; Balch, C.D.; Jorgensen, G.J.; Wendelin, T.; Lewandowski, A.

    1991-11-01

    Research at SERI within the Department of Energy`s Solar Thermal Technology Program has focused on the development of membrane dish concentrators for space and terrestrial power applications. As potentially lightweight, inexpensive, high-performance structures, they are excellent candidates for space-deployable energy sources as well as cost-effective terrestrial energy concepts. A thorough engineering research treatment of these types of structures consists primarily of two parts: (1) structural mechanics of the membrane and ring support and (2) analysis and characterization of the concentrator optical performance. It is important to understand the effects of the membrane`s structure and support system on the optical performance of the concentrator. This requires an interface between appropriate structural and optical models. Until recently, such models and the required interface have not existed. This report documents research that has been conducted at SERI in this area. It is a compilation of several papers describing structural models of membrane dish structures and optical models used to predict dish concentrator optical and thermal performance. The structural models were developed under SERI subcontract by Dr. Steele and Dr. Balch of Stanford University. The optical model was developed in-house by SERI staff. In addition, the interface between the models is described. It allows easy and thorough characterization of membrane dish systems from the mechanics to the resulting optical performance. The models described herein have been and continue to be extremely useful to SERI, industry, and universities involved with the modeling and analysis of lightweight membrane concentrators for solar thermal applications.

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

    Science.gov (United States)

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

    2017-05-01

    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

  2. Significant ELCAP analysis results: Summary report. [End-use Load and Consumer Assessment Program

    Energy Technology Data Exchange (ETDEWEB)

    Pratt, R.G.; Conner, C.C.; Drost, M.K.; Miller, N.E.; Cooke, B.A.; Halverson, M.A.; Lebaron, B.A.; Lucas, R.G.; Jo, J.; Richman, E.E.; Sandusky, W.F. (Pacific Northwest Lab., Richland, WA (USA)); Ritland, K.G. (Ritland Associates, Seattle, WA (USA)); Taylor, M.E. (USDOE Bonneville Power Administration, Portland, OR (USA)); Hauser, S.G. (Solar Energy Research Inst., Golden, CO (USA))

    1991-02-01

    The evolution of the End-Use Load and Consumer Assessment Program (ELCAP) since 1983 at Bonneville Power Administration (Bonneville) has been eventful and somewhat tortuous. The birth pangs of a data set so large and encompassing as this have been overwhelming at times. The early adolescent stage of data set development and use has now been reached and preliminary results of early analyses of the data are becoming well known. However, the full maturity of the data set and the corresponding wealth of analytic insights are not fully realized. This document is in some sense a milestone in the brief history of the program. It is a summary of the results of the first five years of the program, principally containing excerpts from a number of previous reports. It is meant to highlight significant accomplishments and analytical results, with a focus on the principal results. Many of the results have a broad application in the utility load research community in general, although the real breadth of the data set remains largely unexplored. The first section of the document introduces the data set: how the buildings were selected, how the metering equipment was installed, and how the data set has been prepared for analysis. Each of the sections that follow the introduction summarize a particular analytic result. A large majority of the analyses to date involve the residential samples, as these were installed first and had highest priority on the analytic agenda. Two exploratory analyses using commercial data are included as an introduction to the commercial analyses that are currently underway. Most of the sections reference more complete technical reports which the reader should refer to for details of the methodology and for more complete discussion of the results. Sections have been processed separately for inclusion on the data base.

  3. Summary report for Group X6: Heat removal system and system analysis

    Energy Technology Data Exchange (ETDEWEB)

    Leung, W

    2005-12-15

    This report is a summary of the activities of the X6 design support for the Heat Removal System (HRS) of MEGAPIE. It can be divided into two main parts: The first part is about the design and manufacturing of he cooling loop (the first 3 chapters), and the second part is dealing with the thermal hydraulic analysis of the overall HRS. This also reflects the change of the X6 activities from design to operation support. The activities of this group are more or less driven by the needs rather than a complete set of tasks given at the start of the project. The first part chronicles the system development. Some of the arguments are probably outdated but are kept in the original form to illustrate the evolution of concepts. The main objective is, of course, to design a heat removal system that can cool the liquid metal spallation target for a 1 MW proton beam i.e. 1.74 mA in 575 MeV). It is also reckoned that the liquid metal, BE (lead-bismuth-eutectic), must be kept liquid even when the proton beam was switched off. This requires either that the cooling system can be shut down or the operating temperature of the coolant be higher than the freezing point of LBE. As for safety concerns, the HRS system must not exert a pressure that exceeds the design pressure of the target beam window in case of a break at the target heat exchanger (THX); this limits the cover gas pressure to about 4 bar(a). These are the basic design principles that carry through the conceptual and engineering design of he system. The organic coolant Diphyl THT was then chosen, because of its wide range of operating temperature (i.e. from 0 to 340 degC) and high boiling point, and a proven record in industrial applications. (author)

  4. Co-morbidities in patients with heart failure : an analysis of the European Heart Failure Pilot Survey

    NARCIS (Netherlands)

    van Deursen, Vincent M.; Urso, Renato; Laroche, Cecile; Damman, Kevin; Dahlstrom, Ulf; Tavazzi, Luigi; Maggioni, Aldo P.; Voors, Adriaan A.

    2014-01-01

    Aims Co-morbidities frequently accompany heart failure (HF), contributing to increased morbidity and mortality, and an impairment of quality of life. We assessed the prevalence, determinants, regional variation, and prognostic implications of co-morbidities in patients with chronic HF in Europe. Met

  5. Failure Mode and Effect Analysis in Increasing the Revenue of Emergency Department

    Directory of Open Access Journals (Sweden)

    Farhad Rahmati

    2015-02-01

    Full Text Available Introduction: Successful performance of emergency department(ED is one of the important indications of increasing the satisfaction among referees. The insurance of such successful performance is fiscal discipline and avoiding from non-beneficial activities in this department. Therefore, the increasing revenue of emergency department is one of the interested goals of hospital management system. According to above-mentioned, the researchers assessed problems lead to loss the revenue of ED and eliminate them by using failure mode and effects analysis (FMEA.Methods: This was the prospective cohort study performed during 18 months, set in 6 phases. In the first phase, the failures were determined and some solutions suggested to eliminate them. During 2-5 phases, based on the prioritizing the problems, solutions were performed. In the sixth phase, final assessment of the study was done. Finally, the feedback of system’s revenue was evaluated and data analyzed using repeated measure ANOVA.Results: Lack of recording the consuming instrument and attribution of separate codes for emergency services of hospitalized patients were the most important failures that lead to decrease the revenue of ED. Such elimination caused to 75.9% increase in revenue within a month (df = 1.6; F = 84.0; p<0.0001.  Totally, 18 months following the eliminating of failures caused to 328.2% increase in the revenue of ED (df = 15.9; F = 215; p<0.0001.Conclusion: The findings of the present study shows that failure mode and effect analysis, can be used as a safe and effected method to reduce the expenses of ED and increase its revenue.

  6. Do antibiotics decrease implant failure and postoperative infections? A systematic review and meta-analysis.

    Science.gov (United States)

    Ata-Ali, J; Ata-Ali, F; Ata-Ali, F

    2014-01-01

    The purpose of this study was to systematically review and perform a comprehensive meta-analysis of the current literature to answer the following question: among patients receiving dental implants, does the use of antibiotics, when compared with a control group, reduce the frequency of implant failure and postoperative infection? A manual and electronic PubMed search of the literature was made to identify randomized controlled trials (RCTs) on the efficacy of antibiotics compared with a control group (not receiving antibiotics or receiving placebo). Four RCTs were included in the final review. These four RCTs grouped a total of 2063 implants and a total of 1002 patients. Antibiotic use significantly lowered the implant failure rate (P = 0.003), with an odds ratio of 0.331, implying that antibiotic treatment reduced the odds of failure by 66.9%. The number needed to treat (NNT) to prevent one patient from having an implant failure was 48 (95% confidence interval 31-109). In contrast, antibiotic use did not significantly reduce the incidence of postoperative infection (P = 0.754). Based on the results of this meta-analysis, and pending further research in the field, it can be concluded that there is evidence in favour of systematic antibiotic use in patients receiving dental implants, since such treatment significantly reduces implant failure. In contrast, antibiotic use does not exert a significant preventive effect against postoperative infection. Our recommendations for future research focus on the performance of large-scale RCTs to identify the best choice of antibiotic, timing of administration, and dose. Increased effort is also required to reach consensus and define the most effective antibiotic treatment protocol for patients who are allergic to beta-lactams and for those who are not.

  7. User-defined Material Model for Thermo-mechanical Progressive Failure Analysis

    Science.gov (United States)

    Knight, Norman F., Jr.

    2008-01-01

    Previously a user-defined material model for orthotropic bimodulus materials was developed for linear and nonlinear stress analysis of composite structures using either shell or solid finite elements within a nonlinear finite element analysis tool. Extensions of this user-defined material model to thermo-mechanical progressive failure analysis are described, and the required input data are documented. The extensions include providing for temperature-dependent material properties, archival of the elastic strains, and a thermal strain calculation for materials exhibiting a stress-free temperature.

  8. Predictive value of plasma copeptin level for the risk and mortality of heart failure: a meta-analysis.

    Science.gov (United States)

    Yan, Jian-Jun; Lu, Ying; Kuai, Zheng-Ping; Yong, Yong-Hong

    2017-02-28

    Epidemiologic studies are inconsistent regarding the association between plasma copeptin level and heart failure (HF). The aim of this study was to perform a meta-analysis to determine whether high level of copeptin is correlated with incidence of HF and mortality in patients with HF. We searched PUBMED and EMBASE databases for studies conducted from 1966 through May 2016 to identify studies reporting hazard ratio (HR) estimates with 95% confidence intervals (CIs) for the association between plasma copeptin level and HF. A random-effects model was used to combine study-specific risk estimates. A total of 13 studies were included in the meta-analysis, with five studies on the incidence of HF and eight studies on the mortality of patients with HF. For incidence of HF, the summary HR indicated a borderline positive association of high plasma copeptin level with HF risk (HR, 1.60; 95% CI, 0.90-2.85). Furthermore, an increase of 1 standard deviation in log copeptin level was associated with a 17% increase in the risk of incident HF (HR, 1.17; 95% CI, 1.02-1.33). For all-cause mortality of patients with HF, we also found a significant association between elevated plasma copeptin level and increased mortality of HF (HR, 1.76; 95% CI, 1.33-2.33). Our dose-response analysis indicated that an increment in copeptin level of 1 pmol/l was associated with a 3% increase in all-cause mortality (HR, 1.03; 95% CI, 1.01-1.05). In conclusion, our results suggest that elevated plasma copeptin level is associated with an increased risk of HF and all-cause mortality in patients with HF.

  9. Failure Analysis of PRDS Pipe in a Thermal Power Plant Boiler

    Science.gov (United States)

    Ghosh, Debashis; Ray, Subrata; Mandal, Jiten; Mandal, Nilrudra; Shukla, Awdhesh Kumar

    2016-06-01

    The pressure reducer desuperheater (PRDS) pipeline is used for reducing the pressure and desuperheating of the steam in different auxiliary pipeline. When the PRDS pipeline is failed, the reliability of the boiler is affected. This paper investigates the probable cause/causes of failure of the PRDS tapping line. In that context, visual inspection, outside diameter and wall thickness measurement, chemical analysis, metallographic examination and hardness measurement are conducted as part of the investigative studies. Apart from these tests, mechanical testing and fractographic analysis are also conducted as supplements. Finally, it has been concluded that the PRDS pipeline has mainly failed due to graphitization due to prolonged exposure of the pipe at higher temperature. The improper material used is mainly responsible for premature failure of the pipe.

  10. Numerical simulation and factor analysis of petrochemical pipe erosion-corrosion failure

    Science.gov (United States)

    XU, G. F.; OU, G. F.; Chen, T.; Li, P. X.; JIN, H. Z.

    2016-05-01

    Based on the behavior of carbon steel outlet tube in REAC pipes of Zhenhai Refining & Chemical Company, the mathematical model of fluid-solid interaction was established according to the mechanism of erosion-corrosion damage. The interaction between corrosion products protecting film and multiphase liquid was analyzed by numerical simulation method. The distribution of shearing stress on the inwall of elbow bend, and the distribution of principal displacement, stress and strain of corrosion products protecting film were disclosed, while the erosion-corrosion failure processes was studied. The simulation result coincides with that of the positioned thickness gauging which validated the reliability and feasibility of the finite element analysis software simulation method. The obtained results can be used in the erosion-corrosion failure analysis, structural optimization, in-service testing positioning, life prediction, risk assessment, safety and other security projects for multiphase flow pipeline.

  11. Regression Analysis of Right-censored Failure Time Data with Missing Censoring Indicators

    Institute of Scientific and Technical Information of China (English)

    Ping Chen; Ren He; Jun-shan Shen; Jian-guo Sun

    2009-01-01

    This paper discusses regression analysis of right-censored failure time data when censoring indicators are missing for some subjects. Several methods have been developed for the analysis under different situations and especially, Goetghebeur and Ryan[4] considered the situation where both the failure time and the censoring time follow the proportional hazards models marginally and developed an estimating equation approach. One limitation of their approach is that the two baseline hazard functions were assumed to be proportional to each other. We consider the same problem and present an efficient estimation procedure for regression parameters that does not require the proportionality assumption. An EM algorithm is developed and the method is evaluated by a simulation study, which indicates that the proposed methodology performs well for practical situations. An illustrative example is provided.

  12. Process-Oriented Development of Failure Reporting, Analysis, and Corrective Action System

    Directory of Open Access Journals (Sweden)

    Jae Hoon Lee

    2010-01-01

    Full Text Available Although failure reporting, analysis, and corrective action system (FRACAS has two management perspectives, its tasks and related information, the previous researches and applications mainly have focused on the data management. This study is to develop a process-oriented FRACAS which supports the operation of the failure-related activities. The development procedures are (1 to define the reporting and analysis tasks, (2 to define the information to be used at each task, and (3 to design a computerized business process model and set the attributes such as durations, rules, and document types. This computerized FRACAS process can be activated in a business process management system (BPMS which employs the enactment functions, deliver tasks to the proper workers, provide the necessary information, and alarm the abnormal status of the tasks (delay, incorrect delivery, cancellation. Through implementing the prototype system, improvements are found for automation of the tasks, prevention of disoperation, and real-time activity monitoring.

  13. Using Healthcare Failure Mode and Effect Analysis to Reduce Intravenous Chemotherapy Errors in Chinese Hospitalized Patients.

    Science.gov (United States)

    Li, Gui; Xu, Bo; He, Rui-Xian; Zhang, Shu-Xiang

    Intravenous chemotherapy administration is a high-risk process; attention must be paid to preventing errors that might occur during the administration of chemotherapy. The aim of this study is to investigate whether the healthcare failure mode and effect analysis (HFMEA) is a valid proactive method to apply to chemotherapy administration in the Chinese oncology inpatient setting. A multidisciplinary team created a flow diagram of the chemotherapy administration process and potential failure modes were identified and evaluated using a hazard-scoring matrix. Using a decision tree, failure mode recommendations were made. Chemotherapy error rates before and after the HFMEA were compared. A total of 5 failure modes were identified with high hazard scores, and 15 recommendations were made. After the intervention, the chemotherapy error rate decreased significantly from 2.05% to 0.17%. The complexity of intravenous chemotherapy makes it vulnerable to error, and with serious consequences. Multiple errors can occur during ordering, preparing, compounding, dispensing, and administering the chemotherapy. The process of HFMEA helped reduce the chemotherapy error rate in Chinese hospitalized patients. Clinicians in oncology can take effective measures to avoid chemotherapy errors using the HFMEA.

  14. Energy analysis of face stability of deep rock tunnels using nonlinear Hoek-Brown failure criterion

    Institute of Scientific and Technical Information of China (English)

    张佳华; 李永鑫; 许敬叔

    2015-01-01

    The nonlinear Hoek-Brown failure criterion was introduced to limit analysis by applying the tangent method. Based on the failure mechanism of double-logarithmic spiral curves on the face of deep rock tunnels, the analytical solutions of collapse pressure were derived through utilizing the virtual power principle in the case of pore water, and the optimal solutions of collapse pressure were obtained by using the optimization programs of mathematical model with regard of a maximum problem. In comparison with existing research with the same parameters, the consistency of change rule shows the validity of the proposed method. Moreover, parametric study indicates that nonlinear Hoek-Brown failure criterion and pore water pressure have great influence on collapse pressure and failure shape of tunnel faces in deep rock masses, particularly when the surrounding rock is too weak or under the condition of great disturbance and abundant ground water, and in this case, supporting measures should be intensified so as to prevent the occurrence of collapse.

  15. Failure Analysis in Magnetic Tunnel Junction Nanopillar with Interfacial Perpendicular Magnetic Anisotropy

    Directory of Open Access Journals (Sweden)

    Weisheng Zhao

    2016-01-01

    Full Text Available Magnetic tunnel junction nanopillar with interfacial perpendicular magnetic anisotropy (PMA-MTJ becomes a promising candidate to build up spin transfer torque magnetic random access memory (STT-MRAM for the next generation of non-volatile memory as it features low spin transfer switching current, fast speed, high scalability, and easy integration into conventional complementary metal oxide semiconductor (CMOS circuits. However, this device suffers from a number of failure issues, such as large process variation and tunneling barrier breakdown. The large process variation is an intrinsic issue for PMA-MTJ as it is based on the interfacial effects between ultra-thin films with few layers of atoms; the tunneling barrier breakdown is due to the requirement of an ultra-thin tunneling barrier (e.g., <1 nm to reduce the resistance area for the spin transfer torque switching in the nanopillar. These failure issues limit the research and development of STT-MRAM to widely achieve commercial products. In this paper, we give a full analysis of failure mechanisms for PMA-MTJ and present some eventual solutions from device fabrication to system level integration to optimize the failure issues.

  16. Using causal reasoning for automated failure modes and effects analysis (FMEA)

    Science.gov (United States)

    Bell, Daniel; Cox, Lisa; Jackson, Steve; Schaefer, Phil

    The authors have developed a tool that automates the reasoning portion of a failure modes and effects analysis (FMEA). It is built around a flexible causal reasoning module that has been adapted to the FMEA procedure. The approach and software architecture have been proven. A prototype tool has been created and successfully passed a test and evaluation program. The authors are expanding the operational capability and adapting the tool to various CAD/CAE (computer-aided design and engineering) platforms.

  17. INTEGRATION OF POKA YOKE INTO PROCESS FAILURE MODE AND EFFECT ANALYSIS: A CASE STUDY

    OpenAIRE

    A. P. Puvanasvaran; N. Jamibollah; N. Norazlin

    2014-01-01

    The Failure Mode and Effect Analysis (FMEA) is a one of the requirements which was required by the Automotive Industries Action Group (AIAG) to all the automotive suppliers and manufacturers worldwide through the TS16949 Quality System. There were a lot of dicrepencies detected on implementing the FMEA which directly related to the user experinces and knowledge. The descrepencies cause the FMEA not meeting the objectives of it. Conceptually, Poka Yoke is able to fit into the Process FMEA. Fai...

  18. A failure analysis study on the fractured connecting bolts of a filter press

    Directory of Open Access Journals (Sweden)

    Sh. Molaei

    2015-10-01

    Full Text Available The purpose of this study was to investigate the main causes of the co-fracture of sixteen connecting bolts of a filter press cylinder–piston system. Stress state of the bolts during the service conditions has been analyzed and the failure reasons were determined from the fractography analysis and gathered information. According to the obtained results, it was concluded that the bolts had failed by the fatigue mechanism. It seems that insufficient torque was used during assembly.

  19. MO-D-BRB-07: Failure-Mode and Effects Analysis Study for CyberKnife Stereotactic Radiosurgery.

    Science.gov (United States)

    Dieterich, S; Ford, E; Halasz, C

    2012-06-01

    The purpose of this study is to conduct a Failure Modes and Effect Analysis (FMEA) for CyberKnife Stereotactic Radiosurgery to determine the sensitivity of existing QA procedures and determine in which areas new QA procedures needed to be implemented. Members from each professional team providing service for CyberKnife radiosurgery (Medical Physicists, Nurses, Physicians, Radiation Therapists, and Administrators) were interviewed to gather potential failure modes. A patient flow chart was developed from patient consult to conclusion of last treatment. Failure modes were mapped to nodes in the flow charts to identify potential high-risk areas. A matrix was created to correlate existing QA procedures with failure modes to identify failure modes that were not covered by any QA as well as identify the sensitivity of QA procedures to prevent failures. 180 failure modes were identified. Current AAPM QA recommendations were found to focus preferentially on technical failure modes (15%), while the majority of failure modes found are process failures and human errors (85%). Creating a Venn diagram of CyberKnife and Gamma Knife failure modes revealed a large overlap area. The most effective QA checks are checklists for physics second chart review and pre- treatment time-out checklists. Existing checklists were modified and new checklists added to address high-ranked failure modes. New procedure guidelines, e.g. for contouring workflow and add-on simulations, were developed as QC to address clusters of failure modes. An ARIA-CyberKnife DICOM interface is being implemented to resolve failure modes centering around multiple fraction, multiple plan treatments and total dose tracking. This work is the first FMEA study for the CyberKnife stereotactic radiosurgery. It will facilitate medical physicists using the CyberKnife to deliver SRS/SBRT treatments to transition from experience-based technical QA to a comprehensive new quality paradigm including technical, process, and human

  20. Top-down and bottom-up definitions of human failure events in human reliability analysis

    Energy Technology Data Exchange (ETDEWEB)

    Boring, Ronald Laurids [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-10-01

    In the probabilistic risk assessments (PRAs) used in the nuclear industry, human failure events (HFEs) are determined as a subset of hardware failures, namely those hardware failures that could be triggered by human action or inaction. This approach is top-down, starting with hardware faults and deducing human contributions to those faults. Elsewhere, more traditionally human factors driven approaches would tend to look at opportunities for human errors first in a task analysis and then identify which of those errors is risk significant. The intersection of top-down and bottom-up approaches to defining HFEs has not been carefully studied. Ideally, both approaches should arrive at the same set of HFEs. This question is crucial, however, as human reliability analysis (HRA) methods are generalized to new domains like oil and gas. The HFEs used in nuclear PRAs tend to be top-down—defined as a subset of the PRA—whereas the HFEs used in petroleum quantitative risk assessments (QRAs) often tend to be bottom-up—derived from a task analysis conducted by human factors experts. The marriage of these approaches is necessary in order to ensure that HRA methods developed for top-down HFEs are also sufficient for bottom-up applications.

  1. Summary and Analysis of the U.S. Government Bat Banding Program

    Science.gov (United States)

    Ellison, Laura E.

    2008-01-01

    buried in the BBP files for further analyses. Lastly, I make several recommendations based on the findings of this summary and analysis, the most important of which is that marking bats with standard metal or split-ring forearm bands should not be considered for mark-recapture studies unless the information sought and the potential for obtaining unbiased estimates from that information vastly outweighs the potential negative effects to the bats.

  2. An Efficient Approach for the Reliability Analysis of Phased-Mission Systems with Dependent Failures

    Science.gov (United States)

    Xing, Liudong; Meshkat, Leila; Donahue, Susan K.

    2006-01-01

    We consider the reliability analysis of phased-mission systems with common-cause failures in this paper. Phased-mission systems (PMS) are systems supporting missions characterized by multiple, consecutive, and nonoverlapping phases of operation. System components may be subject to different stresses as well as different reliability requirements throughout the course of the mission. As a result, component behavior and relationships may need to be modeled differently from phase to phase when performing a system-level reliability analysis. This consideration poses unique challenges to existing analysis methods. The challenges increase when common-cause failures (CCF) are incorporated in the model. CCF are multiple dependent component failures within a system that are a direct result of a shared root cause, such as sabotage, flood, earthquake, power outage, or human errors. It has been shown by many reliability studies that CCF tend to increase a system's joint failure probabilities and thus contribute significantly to the overall unreliability of systems subject to CCF.We propose a separable phase-modular approach to the reliability analysis of phased-mission systems with dependent common-cause failures as one way to meet the above challenges in an efficient and elegant manner. Our methodology is twofold: first, we separate the effects of CCF from the PMS analysis using the total probability theorem and the common-cause event space developed based on the elementary common-causes; next, we apply an efficient phase-modular approach to analyze the reliability of the PMS. The phase-modular approach employs both combinatorial binary decision diagram and Markov-chain solution methods as appropriate. We provide an example of a reliability analysis of a PMS with both static and dynamic phases as well as CCF as an illustration of our proposed approach. The example is based on information extracted from a Mars orbiter project. The reliability model for this orbiter considers

  3. GNEP Material Transportation, Storage and Disposal Analysis FY-08 Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Halsey, W

    2009-01-15

    This report provides a summary for FY-2008 of activities, analyses and products from the Material Transportation, Storage and Disposal (M-TSD) sub-task of Systems Analysis within the Advanced Fuel Cycle Research & Development area of the Global Nuclear Energy Partnership. The objective of this work is to evaluate near-term material management requirements for initial GNEP facilities and activities, long-term requirements for large-scale GNEP technology deployment, and alternatives and paths forward to meet these needs. For FY-08, the work expanded to include the Integrated Waste Management Strategy as well as integration with the newly formed Waste Forms Campaign. The M-TSD team was expanded with the addition of support from Savannah River National Lab (SRNL) to the existing team of Lawrence Livermore National Lab (LLNL), Argonne National Lab (ANL), Idaho National Lab (INL), Sandia National Lab (SNL) and University of Nevada - Reno (UN-R). During the first half of the year, analysis was focused on providing supporting technical analysis and documentation to support anticipated high-level decisions on program direction. A number of analyses were conducted and reports prepared as program deliverables. This work is briefly summarized in this report. Analyses provided informally to other program efforts are included in this report to provide documentation. This year-end summary was planned primarily as a compilation of activities following the anticipated programmatic decisions. These decisions were deferred beyond the end of the year, and funds were reallocated in a number of areas, thus reducing the M-TSD activities. This report summarizes the miscellaneous 'ad-hoc' work conducted during the later part of the year, such as support to the draft Programmatic Environmental Impact Statement (PEIS), and support to other program studies. Major programmatic contributions from the M-TSD team during the year included: (1) Completion of the IWMS in March 2008 as the

  4. GNEP Material Transportation, Storage and Disposal Analysis FY-08 Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Halsey, W

    2009-01-15

    This report provides a summary for FY-2008 of activities, analyses and products from the Material Transportation, Storage and Disposal (M-TSD) sub-task of Systems Analysis within the Advanced Fuel Cycle Research & Development area of the Global Nuclear Energy Partnership. The objective of this work is to evaluate near-term material management requirements for initial GNEP facilities and activities, long-term requirements for large-scale GNEP technology deployment, and alternatives and paths forward to meet these needs. For FY-08, the work expanded to include the Integrated Waste Management Strategy as well as integration with the newly formed Waste Forms Campaign. The M-TSD team was expanded with the addition of support from Savannah River National Lab (SRNL) to the existing team of Lawrence Livermore National Lab (LLNL), Argonne National Lab (ANL), Idaho National Lab (INL), Sandia National Lab (SNL) and University of Nevada - Reno (UN-R). During the first half of the year, analysis was focused on providing supporting technical analysis and documentation to support anticipated high-level decisions on program direction. A number of analyses were conducted and reports prepared as program deliverables. This work is briefly summarized in this report. Analyses provided informally to other program efforts are included in this report to provide documentation. This year-end summary was planned primarily as a compilation of activities following the anticipated programmatic decisions. These decisions were deferred beyond the end of the year, and funds were reallocated in a number of areas, thus reducing the M-TSD activities. This report summarizes the miscellaneous 'ad-hoc' work conducted during the later part of the year, such as support to the draft Programmatic Environmental Impact Statement (PEIS), and support to other program studies. Major programmatic contributions from the M-TSD team during the year included: (1) Completion of the IWMS in March 2008 as the

  5. Failures to further developing orphan medicinal products after designation granted in Europe: an analysis of marketing authorisation failures and abandoned drugs.

    Science.gov (United States)

    Giannuzzi, Viviana; Landi, Annalisa; Bosone, Enrico; Giannuzzi, Floriana; Nicotri, Stefano; Torrent-Farnell, Josep; Bonifazi, Fedele; Felisi, Mariagrazia; Bonifazi, Donato; Ceci, Adriana

    2017-09-11

    The research and development process in the field of rare diseases is characterised by many well-known difficulties, and a large percentage of orphan medicinal products do not reach the marketing approval.This work aims at identifying orphan medicinal products that failed the developmental process and investigating reasons for and possible factors influencing failures. Drugs designated in Europe under Regulation (European Commission) 141/2000 in the period 2000-2012 were investigated in terms of the following failures: (1) marketing authorisation failures (refused or withdrawn) and (2) drugs abandoned by sponsors during development.Possible risk factors for failure were analysed using statistically validated methods. This study points out that 437 out of 788 designations are still under development, while 219 failed the developmental process. Among the latter, 34 failed the marketing authorisation process and 185 were abandoned during the developmental process. In the first group of drugs (marketing authorisation failures), 50% reached phase II, 47% reached phase III and 3% reached phase I, while in the second group (abandoned drugs), the majority of orphan medicinal products apparently never started the development process, since no data on 48.1% of them were published and the 3.2% did not progress beyond the non-clinical stage.The reasons for failures of marketing authorisation were: efficacy/safety issues (26), insufficient data (12), quality issues (7), regulatory issues on trials (4) and commercial reasons (1). The main causes for abandoned drugs were efficacy/safety issues (reported in 54 cases), inactive companies (25.4%), change of company strategy (8.1%) and drug competition (10.8%). No information concerning reasons for failure was available for 23.2% of the analysed products. This analysis shows that failures occurred in 27.8% of all designations granted in Europe, the main reasons being safety and efficacy issues. Moreover, the stage of development

  6. Failure Mode and Effects Analysis%故障模式与影响分析

    Institute of Scientific and Technical Information of China (English)

    胡仁飞

    2014-01-01

    故障模式与影响分析是一种可靠性设计的重要方法,它对各种可能的风险进行评价、分析,以便在现有技术的基础上消除这些风险或将这些风险减小到可接受水平,已经成为提高产品可靠性重要的途径,得到广泛的应用。文章首先分析软件的错误、缺陷、故障、失效之间的关系,进一步得出故障模式的定义。根据不同的角度将故障模式进行分类,并从影响性、危害性等多个方面分析故障模式。%Failure Mode and Effects Analysis is an important method for reliability design, it can assessment and analysis all possible risks. In order to eliminate these risks on the basis of existing technologies or reduce these risks to an acceptable level, it has be-come an important way to improve product reliability. The article first analyzes the relationship between software error, defect, failure, further get the definition of failure mode . classification the fault depending on the different angle , and analysis failure mode by the impact and hazardous and so on.

  7. Application of failure mode and effects analysis (FMEA) to pretreatment phases in tomotherapy.

    Science.gov (United States)

    Broggi, Sara; Cantone, Marie Claire; Chiara, Anna; Di Muzio, Nadia; Longobardi, Barbara; Mangili, Paola; Veronese, Ivan

    2013-09-06

    The aim of this paper was the application of the failure mode and effects analysis (FMEA) approach to assess the risks for patients undergoing radiotherapy treatments performed by means of a helical tomotherapy unit. FMEA was applied to the preplanning imaging, volume determination, and treatment planning stages of the tomotherapy process and consisted of three steps: 1) identification of the involved subprocesses; 2) identification and ranking of the potential failure modes, together with their causes and effects, using the risk probability number (RPN) scoring system; and 3) identification of additional safety measures to be proposed for process quality and safety improvement. RPN upper threshold for little concern of risk was set at 125. A total of 74 failure modes were identified: 38 in the stage of preplanning imaging and volume determination, and 36 in the stage of planning. The threshold of 125 for RPN was exceeded in four cases: one case only in the phase of preplanning imaging and volume determination, and three cases in the stage of planning. The most critical failures appeared related to (i) the wrong or missing definition and contouring of the overlapping regions, (ii) the wrong assignment of the overlap priority to each anatomical structure, (iii) the wrong choice of the computed tomography calibration curve for dose calculation, and (iv) the wrong (or not performed) choice of the number of fractions in the planning station. On the basis of these findings, in addition to the safety strategies already adopted in the clinical practice, novel solutions have been proposed for mitigating the risk of these failures and to increase patient safety.

  8. Energy analysis of stability of twin shallow tunnels based on nonlinear failure criterion

    Institute of Scientific and Technical Information of China (English)

    张佳华; 许敬叔; 张标

    2014-01-01

    Based on nonlinear Mohr−Coulomb failure criterion, the analytical solutions of stability number and supporting force on twin shallow tunnels were derived using upper bound theorem of limit analysis. The optimized solutions were obtained by the technique of sequential quadratic programming. When nonlinear coefficient equals 1 and internal friction angle equals 0, the nonlinear Mohr−Coulomb failure criterion degenerates into linear failure criterion. The calculated results of stability number in this work were compared with previous results, and the agreement verifies the effectiveness of the present method. Under the condition of nonlinear Mohr−Coulomb failure criterion, the results show that the supporting force on twin shallow tunnels obviously increases when the nonlinear coefficient, burial depth, ground load or pore water pressure coefficients increase. When the clear distance is 0.5 to 1.0 times the diameter of tunnel, the supporting force of twin shallow tunnels reaches its maximum value, which means that the tunnels are the easiest to collapse. While the clear distance increases to 3.5 times the diameter of tunnel, the calculation for twin shallow tunnels can be carried out by the method for independent single shallow tunnel. Therefore, 3.5 times the diameter of tunnel serves as a critical value to determine whether twin shallow tunnels influence each other. In designing twin shallow tunnels, appropriate clear distance value must be selected according to its change rules and actual topographic conditions, meanwhile, the influences of nonlinear failure criterion of soil materials and pore water must be completely considered. During the excavation process, supporting system should be intensified at the positions of larger burial depth or ground load to avoid collapses.

  9. STRESS AND FAILURE ANALYSIS OF RAPIDLY ROTATING ASTEROID (29075) 1950 DA

    Energy Technology Data Exchange (ETDEWEB)

    Hirabayashi, Masatoshi; Scheeres, Daniel J., E-mail: masatoshi.hirabayashi@colorado.edu [Research Associate, Colorado Center for Astrodynamics Research, Aerospace Engineering Sciences, University of Colorado Boulder. (United States)

    2015-01-01

    Rozitis et al. recently reported that near-Earth asteroid (29075) 1950 DA, whose bulk density ranges from 1.0 g cm{sup –3} to 2.4 g cm{sup –3}, is a rubble pile and requires a cohesive strength of at least 44-76 Pa to keep from failing due to its fast spin period. Since their technique for giving failure conditions required the averaged stress over the whole volume, it discarded information about the asteroid's failure mode and internal stress condition. This paper develops a finite element model and revisits the stress and failure analysis of 1950 DA. For the modeling, we do not consider material hardening and softening. Under the assumption of an associated flow rule and uniform material distribution, we identify the deformation process of 1950 DA when its constant cohesion reaches the lowest value that keeps its current shape. The results show that to avoid structural failure the internal core requires a cohesive strength of at least 75-85 Pa. It suggests that for the failure mode of this body, the internal core first fails structurally, followed by the surface region. This implies that if cohesion is constant over the whole volume, the equatorial ridge of 1950 DA results from a material flow going outward along the equatorial plane in the internal core, but not from a landslide as has been hypothesized. This has additional implications for the likely density of the interior of the body.

  10. Early tibial tray failure of a Duracon knee with retrieval analysis.

    Science.gov (United States)

    Ho, Ta-Feng; Tsai, Ruey-Yug; Lee, Pei-Yuan; Ku, Ming-Chou

    2004-09-01

    We report a case of early tibial tray fracture of a Duracon knee prosthesis. Aside from the clinical, radiographic, and gross analysis of the failed prosthesis, we also performed analysis on the retrieved polyethylene component and the fractured tibial baseplate. In the analyses, we noted significant femoral component malalignment, uneven tray cementation, and inherent metallurgical weakness. It appears that the high compressive load on the medial tray resulted in bending fatigue failure. To avoid this complication, it is important to restore the normal alignment of the knee joint and use a polyethylene insert of higher conformity, at least 6 mm thick.

  11. 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.

  12. Design Modification & Failure Analysis of a Driven Plate/Friction Plate of a Clutch using FEA.

    Directory of Open Access Journals (Sweden)

    Marella. Veerendra

    2014-10-01

    Full Text Available Clutch is device which is used to transmit power one component to another. It is a device used to connect the driving shaft to a driven shaft, so that the driven shaft may be started or stopped at will, without stopping the driving shaft. A clutch thus provides an interruptible connection between two rotating shafts Clutches allow a high inertia load to be stated with a small power. The engine power transmitted to the system through the clutch. The failure of such a critical component during service can stall the whole application. The objective of present project is to do analysis on driven plate of a clutch which is often fails during the operation. In this present research work analysis is conducted on driven plate of a clutch used in TATA Vehicle. There are so many complaints are noted against the failure of clutch during heavy loads. The driven main plate failed normally during its operation due to cyclic loading. For this reason we designed the driven plate and modeled in Pro-E and analyzed using FEA package in the process of designing and analyzing the actual design is changed to lower down the failure values. And the design may suggest to the company.

  13. Visibility graph analysis of heart rate time series and bio-marker of congestive heart failure

    Science.gov (United States)

    Bhaduri, Anirban; Bhaduri, Susmita; Ghosh, Dipak

    2017-09-01

    Study of RR interval time series for Congestive Heart Failure had been an area of study with different methods including non-linear methods. In this article the cardiac dynamics of heart beat are explored in the light of complex network analysis, viz. visibility graph method. Heart beat (RR Interval) time series data taken from Physionet database [46, 47] belonging to two groups of subjects, diseased (congestive heart failure) (29 in number) and normal (54 in number) are analyzed with the technique. The overall results show that a quantitative parameter can significantly differentiate between the diseased subjects and the normal subjects as well as different stages of the disease. Further, the data when split into periods of around 1 hour each and analyzed separately, also shows the same consistent differences. This quantitative parameter obtained using the visibility graph analysis thereby can be used as a potential bio-marker as well as a subsequent alarm generation mechanism for predicting the onset of Congestive Heart Failure.

  14. 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.

  15. Gearbox Reliability Collaborative Gearbox 1 Failure Analysis Report: December 2010 - January 2011

    Energy Technology Data Exchange (ETDEWEB)

    Errichello, R.; Muller, J.

    2012-02-01

    Unintended gearbox failures have a significant impact on the cost of wind farm operations. In 2007, NREL initiated the Gearbox Reliability Collaborative (GRC). The project combines analysis, field testing, dynamometer testing, condition monitoring, and the development and population of a gearbox failure database in a multi-pronged approach to determine why wind turbine gearboxes do not achieve their expected design life. The collaborative of manufacturers, owners, researchers, and consultants focuses on gearbox testing and modeling and the development of a gearbox failure database. Collaborative members also investigate gearbox condition monitoring techniques. Data gained from the GRC will enable designers, developers, and manufacturers to improve gearbox designs and testing standards and create more robust modeling tools. GRC project essentials include the development of two identical, heavily instrumented representative gearbox designs. Knowledge gained from the field and dynamometer tests conducted on these gearboxes builds an understanding of how the selected loads and events translate into bearing and gear response. This report contains the analysis of the first gearbox design.

  16. Potential failure mode and effects analysis for the ITER NB injector

    Energy Technology Data Exchange (ETDEWEB)

    Boldrin, M.; De Lorenzi, A.; Fiorentin, A.; Grando, L.; Marcuzzi, D.; Peruzzo, S. [Consorzio RFX, Association EURATOM-ENEA, C.so Stati Uniti 4, 35127 Padova (Italy); Pomaro, N. [Consorzio RFX, Association EURATOM-ENEA, C.so Stati Uniti 4, 35127 Padova (Italy)], E-mail: nicola.pomaro@igi.cnr.it; Rigato, W.; Serianni, G. [Consorzio RFX, Association EURATOM-ENEA, C.so Stati Uniti 4, 35127 Padova (Italy)

    2009-06-15

    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.

  17. Using Failure Mode and Effect Analysis (FMEA for Performing Good Ploughing with Mouldboard

    Directory of Open Access Journals (Sweden)

    M Namdari

    2011-03-01

    Full Text Available Farm management needs creative methods to success. FMEA (Failure Modes and Effects Analysis is a new method to analyze potential reliability problems in the development cycle of the project, making it easier to take actions to overcome such issues, thus enhancing the reliability through design or process. Anticipating these failure modes, being the central step in the analysis, needs to be carried on extensively, in order to prepare a list of maximum potential failure modes. Risk is measured in terms of Risk Priority Number (RPN that is a product of occurrence, severity, and detection difficulty. This study attempted to improve clod mean weight diameter and soil inversion as indicators of tillage quality by FMEA methodology. The results showed that low soil moisture, slow speed of ploughing and great depth of ploughing is the most important factors that increase clod MWD with 900, 630 and 560 RPN, respectively. Also for soil inversion the slow speed of ploughing, not using coulter, low soil moisture and great depth of ploughing are important factors with 720, 648, 490 and 420 RPN. Using a split - split factorial experiment with 16 treatments and three replications also acknowledged the results of this method. After reforming the conditions and re-testing the experiment, results showed that clod MWD was reduced 20% and soil inversion increased 2% approximately. This study proposes the use of this technique in agricultural management.

  18. Using Failure Mode and Effects Analysis to design a comfortable automotive driver seat.

    Science.gov (United States)

    Kolich, Mike

    2014-07-01

    Given enough time and use, all designs will fail. There are no fail-free designs. This is especially true when it comes to automotive seating comfort where the characteristics and preferences of individual customers are many and varied. To address this problem, individuals charged with automotive seating comfort development have, traditionally, relied on iterative and, as a result, expensive build-test cycles. Cost pressures being placed on today's vehicle manufacturers have necessitated the search for more efficient alternatives. This contribution aims to fill this need by proposing the application of an analytical technique common to engineering circles (but new to seating comfort development), namely Design Failure Mode and Effects Analysis (DFMEA). An example is offered to describe how development teams can use this systematic and disciplined approach to highlight potential seating comfort failure modes, reduce their risk, and bring capable designs to life.

  19. Reliability Analysis of Fatigue Failure of Cast Components for Wind Turbines

    DEFF Research Database (Denmark)

    Rafsanjani, Hesam Mirzaei; Sørensen, John Dalsgaard

    2015-01-01

    are different for offshore and onshore wind turbines. Moreover, uncertainties about the fatigue strength play an important role in modeling and assessment of the reliability of the components. In this paper, a generic stochastic model for fatigue failure of cast iron components based on fatigue test data...... and a limit state equation for fatigue failure based on the SN-curve approach and Miner’s rule is presented. The statistical analysis of the fatigue data is performed using the Maximum Likelihood Method which also gives an estimate of the statistical uncertainties. Finally, illustrative examples are presented...... to substantial economic losses such as cost of lost energy production and cost of repairs. During the design lifetime, the drivetrain components are exposed to variable loads from winds and waves and other sources of loads that are uncertain and have to be modeled as stochastic variables. The types of loads...

  20. Nonlinear Progressive Failure Analysis of Surrounding Rock System Based on Similarity Theory

    Directory of Open Access Journals (Sweden)

    Zhao Y.

    2016-01-01

    Full Text Available Nonlinear progressive failure study of surrounding rock is important for the stability analysis of underground engineering projects. Taking a deep-buried tunnel in Chongqing as an example, a three dimensional(3-D physical model was established based on similarity theory. To satisfy similarity requirement of physical–mechanical properties, such as elastic modulus, compressive strength and Poisson ratio, physical model materials were developed. Using full inner-spy photograph technology, the deformation and failure process of rock were studied under the situation of independent and combined action of anchor, shotcrete and reinforcing mesh. Based on experimental results, the interaction mechanism between rock and support structure under high stress was investigated.

  1. Failure Analysis of X80 Line Pipe’s Circumferential Weld

    Directory of Open Access Journals (Sweden)

    Liu Hong Liang

    2016-01-01

    Full Text Available One 530mm X80 pipeline weld failed infrequently in service process. This paper gives a systematic analysis in consideration of both material quality and loading condition. Inspection was performed on chemical composition, mechanical performance, metallograghy and micro-morphology. The result shows that weld joint’s leakage failure accident is fatigue failure. Under the effect of tensile- tensile stress fatigue stress, fatigue crack originated from weld fusion line near the pipe body and developed along the weld. Porosity defect in the weld reduced its bearing capacity, and promoted the formation and development of the fatigue crack. Fatigue strength and fatigue life of the weld has great relationship with the size and distribution of porosity. The greater the porosity, the more close to surface, the decrease of fatigue life is more obvious.

  2. A Modified Model of Failure Mode and Effects Analysis Based on Generalized Evidence Theory

    Directory of Open Access Journals (Sweden)

    Deyun Zhou

    2016-01-01

    Full Text Available Due to the incomplete knowledge, how to handle the uncertain risk factors in failure mode and effects analysis (FMEA is still an open issue. This paper proposes a new generalized evidential FMEA (GEFMEA model to handle the uncertain risk factor, which may not be included in the conventional FMEA model. In GEFMEA, not only the conventional risk factors, the occurrence, severity, and detectability of the failure mode, but also the other incomplete risk factors are taken into consideration. In addition, the relative importance among all these risk factors is well addressed in the proposed method. GEFMEA is based on the generalized evidence theory, which is efficient in handling incomplete information in the open world. The efficiency and some merit of the proposed method are verified by the numerical example and a real case study on aircraft turbine rotor blades.

  3. Launch Vehicle Abort Analysis for Failures Leading to Loss of Control

    Science.gov (United States)

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

    2013-01-01

    Launch vehicle ascent is a time of high risk for an onboard crew. 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 on data already available from the Guidance, Navigation, and Control system. This work is the result of failure analysis efforts performed during the Ares I launch vehicle development program. The two primary areas of focus are the derivation of abort triggers to ensure that abort occurs as quickly as possible when needed, but that false aborts are avoided, and evaluation of success in aborting off the failing launch vehicle.

  4. Failure mode and effect analysis on safety critical components of space travel

    Directory of Open Access Journals (Sweden)

    Kouroush Jenab

    2015-07-01

    Full Text Available Sending men to space has never been an ordinary activity, it requires years of planning and preparation in order to have a chance of success. The payoffs of reliable and repeatable space flight are many, including both Commercial and Military opportunities. In order for reliable and repeatable space flight to become a reality, catastrophic failures need to be detected and mitigated before they occur. It can be shown that small pieces of a design which seem ordinary can create devastating impacts if not designed and tested properly. This paper will address the use of a Failure Mode, Effects, and Criticality Analysis (FMECA with modified Risk Priority Number (RPN and its application to safety critical design components of shuttle liftoff. An example will be presented here which specifically focuses on the Solid Rocket Boosters (SRBs to illustrate the FMECA approach to reliable space travel.

  5. Failure analysis of corrosion cracking and simulated testing for a fluid catalytic cracking unit

    Institute of Scientific and Technical Information of China (English)

    Hua Chen; Xiaogang Li; Chaofang Dong; Ming Li; Jinwen Yang

    2005-01-01

    The failure of a fluid catalysis and cracking unit (FCCU) in a Chinese refinery was investigated by using nondestructive detection methods, fracture surface examination, hardness measurement, chemical composition and corrosion products analysis. The results showed that the failure was caused by the dew point nitrate stress corrosion cracking. For a long operation period, the wall temperature of the regenerator in the FCCU was below the fume dew point. As a result, an acid fume NOx-SOx-H2O medium presented on the surface, resulting in stress corrosion cracking of the component with high residual stress. In order to confirm the relative conclusion, simulated testing was conducted in laboratory, and the results showed similar cracking characteristics. Finally, some suggestions have been made to prevent the stress corrosion cracking of an FCCU from re-occurring in the future.

  6. Interfacing LabVIEW With Instrumentation for Electronic Failure Analysis and Beyond

    Science.gov (United States)

    Buchanan, Randy K.; Bryan, Coleman; Ludwig, Larry

    1996-01-01

    The Laboratory Virtual Instrumentation Engineering Workstation (LabVIEW) software is designed such that equipment and processes related to control systems can be operationally lined and controlled by the use of a computer. Various processes within the failure analysis laboratories of NASA's Kennedy Space Center (KSC) demonstrate the need for modernization and, in some cases, automation, using LabVIEW. An examination of procedures and practices with the Failure Analaysis Laboratory resulted in the conclusion that some device was necessary to elevate the potential users of LabVIEW to an operational level in minimum time. This paper outlines the process involved in creating a tutorial application to enable personnel to apply LabVIEW to their specific projects. Suggestions for furthering the extent to which LabVIEW is used are provided in the areas of data acquisition and process control.

  7. On the failure analysis of bondlines: Stress or energy based fracture criteria?

    DEFF Research Database (Denmark)

    Anyfantis, Konstantinos

    2014-01-01

    that characterizes a given bondline, both its cohesive strength and fracture toughness material parameters must be experimentally defined. Based on these properties, failure analysis of the bondline can be done either through stress- or energy-based criteria. The aim of this work is to investigate the effectiveness...... of each criteria type to effectively predict debonding initiation/propagation of different bondlines (brittle, quasi-brittle, ductile), which are eventually utilized for the evaluation of the joint's failure load. By representing a bondline according to its cohesive length scale, an effort is made...... experimentation programme. Fracture initiation and propagation of the bondlines was numerically simulated by cohesive zone models. (C) 2014 Elsevier Ltd. All rights reserved....

  8. Integrating decision-making trial and evaluation laboratory model and failure mode and effect analysis to determine the priority in solving production problems

    OpenAIRE

    Yu-Cheng Lee; Wen-Hua Chu; Quan Chen; Sang-Bing Tsai; Jiangtao Wang; Weiwei Dong

    2016-01-01

    Failure mode and effect analysis has been applied in manufacturing and service industries but can still be improved. Failure mode and effect analysis is a common tool used to evaluate risk priority number; however, numerous scholars have doubted the effectiveness of failure mode and effect analysis and have thus proposed methods for correcting failure mode and effect analysis from its conventional formula. Because implemented actions can determine or influence resource allocation and its effe...

  9. 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

  10. River Embankment and Bank Failure: A Study on Geotechnical Characteristics and Stability Analysis

    Directory of Open Access Journals (Sweden)

    M. B. Hossain

    2011-01-01

    Full Text Available Problem statement: Embankment failure and riverbank erosion are common problem in Bangladesh. Almost every year earthen embankments and riverbanks are facing problems like erosion, breaching or retirements. Among many reasons the major causes are considered due to the use of geotechnically unstable materials, improper method of construction, seepage and sliding. In this study the problem is considered geotechnical point of view where the geotechnical properties of failed Jamuna river embankment material and Padma riverbank material were investigated. Moreover, stability analysis technique of embankment has been reviewed through a case study of Manu river embankement. Approach: Sample materials were collected during field investigation and tested at laboratory according to Japanese Industrial Standard (JIS. Limit equilibrium stability analysis and steady state seepage analysis was conducted for Manu river embankment to review the existing design procedure of embankment. Results: Study results reveal that the soil of Jamuna river embankment is not well graded sand and the permeability is found minimum of 1.29×10-5 cm sec−1 (at w = 24% which increases rapidly in submerge condition. The maximum strength is found 51.8 kN m−2 which is not preferable as embankment material. Moreover, the slope is not well protected that makes the embankment vulnerable to erosion. In contrast, the soil of Padma riverbank contains mostly sand with 25% clay content. Both permeability and strength of bank material decrease rapidly with the increase of water content. Nevertheless, tension crack and toe erosion also accelerate the mass failure mechanism of riverbank. From case study the Factor of Safety (FS is found overestimated of about 22-24% in stability analysis of embankment in usual practice. Conclusion: Embankment soil needs to be improved geotechnically to minimize mass failure. Geo-bags, cement composites with reinforcement could be used for

  11. The prognostic value of arterial blood gas analysis in high-risk acute heart failure patients: an analysis of the Korean Heart Failure (KorHF) registry.

    Science.gov (United States)

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

    2015-06-01

    In acute heart failure (AHF) patients, pulmonary oedema and low tissue perfusion may lead to changes in the acid-base balance, which may be associated with worse outcomes. In this prospective nationwide cohort study from 24 academic hospitals, arterial blood gas (ABG) was measured in 1982 AHF patients at hospital admission. Acidosis was defined as pH 7.44. Mortality was stratified according to ABG results. Overall, 19% had acidosis, 37% had normal pH, and 44% had alkalosis. The most common type of acidosis was the mixed type (42%) followed by metabolic acidosis (40%), and the most common type of alkalosis was respiratory alkalosis (58%). At 12 months' follow-up 304 patients (15%) died. Patients with acidosis had higher mortality (acidosis 19.5%, neutral pH 13.7%, alkalosis 14.9%; P = 0.007). In the Cox proportional-hazards regression model, acidosis was a significant predictor of mortality (hazard ratio 1.93; 95% confidence intervals 1.27-2.93) along with N-terminal pro-brain type natriuretic peptide (NT-proBNP), among others. In contrast, alkalosis was not associated with increased mortality. pH had an incremental prognostic value over NT-proBNP (net reclassification improvement 30%; P analysis identified extra patients at increased risk for mortality among patients with an NT-proBNP level less than the median (12-month mortality 17.5% vs. 9.9%; P = 0.009). In high-risk AHF patients, the most common acid-base imbalance is respiratory alkalosis. Acidosis is observed in every fifth patient and is a significant predictor of mortality. pH provides an additional prognostic value and may be used to optimize risk stratification in high-risk AHF patients. © 2015 The Authors. European Journal of Heart Failure © 2015 European Society of Cardiology.

  12. One Size Does Not Fit All: Human Failure Event Decomposition and Task Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ronald Laurids Boring, PhD

    2014-09-01

    In the probabilistic safety assessments (PSAs) used in the nuclear industry, human failure events (HFEs) are determined as a subset of hardware failures, namely those hardware failures that could be triggered or exacerbated by human action or inaction. This approach is top-down, starting with hardware faults and deducing human contributions to those faults. Elsewhere, more traditionally human factors driven approaches would tend to look at opportunities for human errors first in a task analysis and then identify which of those errors is risk significant. The intersection of top-down and bottom-up approaches to defining HFEs has not been carefully studied. Ideally, both approaches should arrive at the same set of HFEs. This question remains central as human reliability analysis (HRA) methods are generalized to new domains like oil and gas. The HFEs used in nuclear PSAs tend to be top-down—defined as a subset of the PSA—whereas the HFEs used in petroleum quantitative risk assessments (QRAs) are more likely to be bottom-up—derived from a task analysis conducted by human factors experts. The marriage of these approaches is necessary in order to ensure that HRA methods developed for top-down HFEs are also sufficient for bottom-up applications. In this paper, I first review top-down and bottom-up approaches for defining HFEs and then present a seven-step guideline to ensure a task analysis completed as part of human error identification decomposes to a level suitable for use as HFEs. This guideline illustrates an effective way to bridge the bottom-up approach with top-down requirements.

  13. Failure mode and effects analysis (FMEA) for the Space Shuttle solid rocket motor

    Science.gov (United States)

    Russell, D. L.; Blacklock, K.; Langhenry, M. T.

    1988-01-01

    The recertification of the Space Shuttle Solid Rocket Booster (SRB) and Solid Rocket Motor (SRM) has included an extensive rewriting of the Failure Mode and Effects Analysis (FMEA) and Critical Items List (CIL). The evolution of the groundrules and methodology used in the analysis is discussed and compared to standard FMEA techniques. Especially highlighted are aspects of the FMEA/CIL which are unique to the analysis of an SRM. The criticality category definitions are presented and the rationale for assigning criticality is presented. The various data required by the CIL and contribution of this data to the retention rationale is also presented. As an example, the FMEA and CIL for the SRM nozzle assembly is discussed in detail. This highlights some of the difficulties associated with the analysis of a system with the unique mission requirements of the Space Shuttle.

  14. Topological Analysis and Mitigation Strategies for Cascading Failures in Power Grid Networks

    CERN Document Server

    Pahwa, Sakshi; Schulz, Noel

    2012-01-01

    Recently, there has been a growing concern about the overload status of the power grid networks, and the increasing possibility of cascading failures. Many researchers have studied these networks to provide design guidelines for more robust power grids. Topological analysis is one of the components of system analysis for its robustness. This paper presents a complex systems analysis of power grid networks. First, the cascading effect has been simulated on three well known networks: the IEEE 300 bus test system, the IEEE 118 bus test system, and the WSCC 179 bus equivalent model. To extend the analysis to a larger set of networks, we develop a network generator and generate multiple graphs with characteristics similar to the IEEE test networks but with different topologies. The generated graphs are then compared to the test networks to show the effect of topology in determining their robustness with respect to cascading failures. The generated graphs turn out to be more robust than the test graphs, showing the...

  15. Numerical analysis of open-hole multilateral completions minimizes the risk of costly junction failures

    Energy Technology Data Exchange (ETDEWEB)

    Suarez-Rivera, Roberto; Martin, J. Wesley [TerraTek, Rio de Janeiro, RJ (Brazil); Begnaud, Bill J. [BHP Billiton Petroleum (Americas) Inc. (United States)

    2004-07-01

    This paper discusses the numerical (3D FEA) modeling of open hole, horizontal, multilateral junctions, to evaluate their mechanical stability under various conditions of junction length, junction orientation, in-situ stress, and rock strength, during drilling and production operations. The objective of the numerical analysis is to evaluate the risk of multilateral junction failure associated to changes in the above parameters for the prediction of minimum rock strength (UCS) required for placing the junction, and for minimizing the risk of junction failure, under various conditions of drawdown and depletion. Results provide clear guidelines for multilateral junction construction (i.e., multilateral geometry), placement (i.e., minimum required rock strength) and safe conditions of operation (i.e., drawdown and depletion). Results also provide critical conditions of drawdown and depletion as a function of rock strength. Furthermore, 3D FEA results show that because of the asymmetry in the junction geometry, the resulting bending moments that develop along the mother-bore and the lateral wellbores reduce the mechanical stability of the multilateral junction. This effect cannot be adequately represented by 2D plane-strain solutions. The discussed methodology will minimize the risk of junction failures resulting in considerable savings to the operator. (author)

  16. Clinical and pathological analysis of IgA nephropathy with chronic renal failure.

    Science.gov (United States)

    Liu, Yuyuan; Hu, Qinfeng; Shen, Ping; Tang, Li; Yuan, Gang; Zhou, Yongmei; Chai, Huaqi

    2016-10-01

    To investigative clinical and pathological characteristics of IgA nephropathy with chronic renal failure. Clinical and pathological findings from 65 cases of IgA nephropathy with chronic renal failure were reviewed. Pathological characteristics of all the cases were analyzed according to WHO definition and Oxford Classification. Evaluating the severity of pathological lesions by the Katafuchi R semiquantitative scoring system, and analyzing their relationship with clinical indexes of renal function. Of all 65 cases the male and female ratio was 1.4, and the mean age was 37 ± 13 years old. Levels of systolic pressure, mean arterial pressure (MAP), blood urea nitrogen (BUN), serum creatinine (Scr), uric acid (UA), album (Alb), serum IgG and 24 h urinary protein were related with eGRF level (p IgA deposition was the most common immunopathologic type. Of all the cases, 44.6% accompanied with C3 while 4.6% with C1q. Further analysis revealed there were no relationships between severity of pathological lesion and levels of clinical indexes (Scr and eGRF) (p > 0.05). IgA nephropathy with chronic renal failure usually occurred in young adults, and it had severe clinical condition and pathological changes, while there was no significant relationship between them.

  17. Analysis of lower head failure with simplified models and a finite element code

    Energy Technology Data Exchange (ETDEWEB)

    Koundy, V. [CEA-IPSN-DPEA-SEAC, Service d' Etudes des Accidents, Fontenay-aux-Roses (France); Nicolas, L. [CEA-DEN-DM2S-SEMT, Service d' Etudes Mecaniques et Thermiques, Gif-sur-Yvette (France); Combescure, A. [INSA-Lyon, Lab. Mecanique des Solides, Villeurbanne (France)

    2001-07-01

    The objective of the OLHF (OECD lower head failure) experiments is to characterize the timing, mode and size of lower head failure under high temperature loading and reactor coolant system pressure due to a postulated core melt scenario. Four tests have been performed at Sandia National Laboratories (USA), in the frame of an OECD project. The experimental results have been used to develop and validate predictive analysis models. Within the framework of this project, several finite element calculations were performed. In parallel, two simplified semi-analytical methods were developed in order to get a better understanding of the role of various parameters on the creep phenomenon, e.g. the behaviour of the lower head material and its geometrical characteristics on the timing, mode and location of failure. Three-dimensional modelling of crack opening and crack propagation has also been carried out using the finite element code Castem 2000. The aim of this paper is to present the two simplified semi-analytical approaches and to report the status of the 3D crack propagation calculations. (authors)

  18. Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.

    2011-01-01

    This article presents summaries of three articles relevant to school crisis response: (1) "Factors Contributing to Posttraumatic Growth," summarized by Steve DeBlois; (2) "Psychological Debriefing in Cross-Cultural Contexts" (Stacey Rice); and (3) "Brain Abnormalities in PTSD" (Sunny Windingstad). The first summary reports the findings of a…

  19. Systems Analysis Programs for Hands-on Intergrated Reliability Evaluations (SAPHIRE) Summary Manual

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Smith

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment (PRA) using a personal computer (PC) running the Microsoft Windows operating system. SAPHIRE is primarily funded by the U.S. Nuclear Regulatory Commission (NRC) and developed by the Idaho National Laboratory (INL). INL's primary role in this project is that of software developer and tester. However, INL also plays an important role in technology transfer by interfacing and supporting SAPHIRE users, who constitute a wide range of PRA practitioners from the NRC, national laboratories, the private sector, and foreign countries. SAPHIRE can be used to model a complex system’s response to initiating events and quantify associated consequential outcome frequencies. Specifically, for nuclear power plant applications, SAPHIRE can identify important contributors to core damage (Level 1 PRA) and containment failure during a severe accident which lead to releases (Level 2 PRA). It can be used for a PRA where the reactor is at full power, low power, or at shutdown conditions. Furthermore, it can be used to analyze both internal and external initiating events and has special features for transforming an internal events model to a model for external events, such as flooding and fire analysis. It can also be used in a limited manner to quantify risk in terms of release consequences to the public and environment (Level 3 PRA). SAPHIRE also includes a separate module called the Graphical Evaluation Module (GEM). GEM is a special user interface linked to SAPHIRE that automates the SAPHIRE process steps for evaluating operational events at commercial nuclear power plants. Using GEM, an analyst can estimate the risk associated with operational events (for example, to calculate a conditional core damage probability) very efficiently and expeditiously. This report provides an overview of the functions

  20. Health-related quality of life and long-term prognosis in chronic hypercapnic respiratory failure: a prospective survival analysis

    Directory of Open Access Journals (Sweden)

    Schmidbauer Kathrin

    2007-12-01

    Full Text Available Abstract Background Health-related quality of life (HRQL is considered as an important outcome parameter in patients with chronic diseases. This study aimed to assess the role of disease-specific HRQL for long-term survival in patients of different diagnoses with chronic hypercapnic respiratory failure (CHRF. Methods In a cohort of 231 stable patients (chronic obstructive pulmonary disease (COPD, n = 98; non-COPD (obesity-hypoventilation syndrome, restrictive disorders, neuromuscular disorders, n = 133 with CHRF and current home mechanical ventilation (HMV, HRQL was assessed by the disease-specific Severe Respiratory Insufficiency (SRI questionnaire and its prognostic value was prospectively evaluated during a follow-up of 2–4 years, using univariate and multivariate regression analysis. Results HRQL was more impaired in COPD (mean ± SD SRI-summary score (SRI-SS 52.5 ± 15.6 than non-COPD patients (67.6 ± 16.4; p 1 turned out to be independent predictors (p Conclusion In patients with CHRF and HMV, the disease-specific SRI was an overall predictor of long-term survival in addition to established risk factors. However, the SRI predominantly beared information regarding long-term survival in non-COPD patients, while in COPD patients objective measures of the disease state were superior. This on one hand highlights the significance of HRQL in the long-term course of patients with CHRF, on the other hand it suggests that the predictive value of HRQL depends on the underlying disease.

  1. Modeling rock failure using the numerical manifold method followed by the discontinuous deformation analysis

    Institute of Scientific and Technical Information of China (English)

    You-Jun Ning; Xin-Mei An; Qing Lü; Guo-Wei Ma

    2012-01-01

    A complete rock failure process usually involves opening/sliding of preexisting discontinuities as well as fracturing in intact rock bridges to form persistent failure surfaces and subsequent motions of the generated rock blocks.The recently developed numerical manifold method (NMM)has potential for modelling such a complete failure process.However,the NMM suffers one limitation,i.e.,unexpected material domain area change occurs in rotation modelling.This problem can not be easily solved because the rigid body rotation is not represented explicitly in the NMM.The discontinuous deformation analysis (DDA) is specially developed for modelling discrete block systems.The rotationinduced material area change in the DDA modelling can be avoided conveniently because the rigid body rotation is represented in an explicit form.In this paper,a transition technique is proposed and implemented to convert a NMM modelling to a DDA modelling so as to simulate a complete rock failure process entirely by means of the two methods,in which the NMM is adopted to model the early fracturing as well as the transition from continua to discontinua,while the DDA is adopted to model the subsequent motion of the generated rock blocks.Such a numerical approach also improves the simulation efficiency greatly as compared with a complete NMM modelling approach.The fracturing of a rock slab with pre-existing non-persistent joints located on a slope crest and the induced rockfall process are simulated.The validity of the modelling transition from the NMM to the DDA is verified and the applicability of the proposed numerical approach is investigated.

  2. Clinical implications of chronic heart failure phenotypes defined by cluster analysis.

    Science.gov (United States)

    Ahmad, Tariq; Pencina, Michael J; Schulte, Phillip J; O'Brien, Emily; Whellan, David J; Piña, Ileana L; Kitzman, Dalane W; Lee, Kerry L; O'Connor, Christopher M; Felker, G Michael

    2014-10-28

    Classification of chronic heart failure (HF) is on the basis of criteria that may not adequately capture disease heterogeneity. Improved phenotyping may help inform research and therapeutic strategies. This study used cluster analysis to explore clinical phenotypes in chronic HF patients. A cluster analysis was performed on 45 baseline clinical variables from 1,619 participants in the HF-ACTION (Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training) study, which evaluated exercise training versus usual care in chronic systolic HF. An association between identified clusters and clinical outcomes was assessed using Cox proportional hazards modeling. Differential associations between clinical outcomes and exercise testing were examined using interaction testing. Four clusters were identified (ranging from 248 to 773 patients in each), in which patients varied considerably among measures of age, sex, race, symptoms, comorbidities, HF etiology, socioeconomic status, quality of life, cardiopulmonary exercise testing parameters, and biomarker levels. Differential associations were observed for hospitalization and mortality risks between and within clusters. Compared with cluster 1, risk of all-cause mortality and/or all-cause hospitalization ranged from 0.65 (95% confidence interval [95% CI]: 0.54 to 0.78) for cluster 4 to 1.02 (95% CI: 0.87 to 1.19) for cluster 3. However, for all-cause mortality, cluster 3 had a disproportionately lower risk of 0.61 (95% CI: 0.44 to 0.86). Evidence suggested differential effects of exercise treatment on changes in peak oxygen consumption and clinical outcomes between clusters (p for interaction Cluster analysis of clinical variables identified 4 distinct phenotypes of chronic HF. Our findings underscore the high degree of disease heterogeneity that exists within chronic HF patients and the need for improved phenotyping of the syndrome. (Exercise Training Program to Improve Clinical Outcomes in Individuals With

  3. CT healthcare failure mode effect analysis (HFMEA): the misadministration of IV contrast in outpatients.

    Science.gov (United States)

    Ouellette-Piazzo, Kathy; Asfaw, Ben; Cowen, June

    2007-01-01

    This article aims to inform and educate healthcare organizations about one of the Joint Commission on Accreditation of Healthcare Organizations (JCAHO) patient safety goals. The goal allows healthcare institutions to be proactive in identifying risks to patient safety and reduce medical errors at the same time. In this article, you will learn what a Healthcare Failure Mode and Effect Analysis (HFMEA) is, how to pick an appropriate topic, and the steps to follow to be able to implement your own HFMEA. The goal of the HFMEA performed at Massachusetts General Hospital (MGH) was to prevent the misadministration of IV contrast in outpatients in the CT department.

  4. A Review of Healthcare Failure Mode and Effects Analysis (HFMEA) in Radiotherapy.

    Science.gov (United States)

    Giardina, M; Cantone, M C; Tomarchio, E; Veronese, I

    2016-10-01

    This paper presents a review of risk analyses in radiotherapy (RT) processes carried out by using Healthcare Failure Mode Effect Analysis (HFMEA) methodology, a qualitative method that proactively identifies risks to patients and corrects medical errors before they occur. This literature review was performed to provide an overview of how to approach the development of HFMEA applications in modern RT procedures, comparing recently published research conducted to support proactive programs to identify risks. On the basis of the reviewed literature, the paper suggests HFMEA shortcomings that need to be addressed.

  5. Shock Analysis on a Packaged Washing Machine from Damage Boundary: Shock Response Spectrum to Component Failure

    Directory of Open Access Journals (Sweden)

    Jing Qian

    2015-01-01

    Full Text Available Both analyses of the damage boundary and shock response spectrum (RSR are the basis for the development of the protective packaging system. The shock analysis through lab test and numerical simulation found that the root cause of packaging failure was due to the stress of the critical component beyond the yield limit of the material. Lab shock test data showed that the packaging design based on the damage boundary is conservative, and the RSR could be helpful and provide support to develop more effective packaging system. Furthermore, numerical simulation can accurately analyze the component and the entire product packaging system in great detail.

  6. Software Tool for Automated Failure Modes and Effects Analysis (FMEA) of Hydraulic Systems

    DEFF Research Database (Denmark)

    Stecki, J. S.; Conrad, Finn; Oh, B.

    2002-01-01

    Offshore, marine,aircraft and other complex engineering systems operate in harsh environmental and operational conditions and must meet stringent requirements of reliability, safety and maintability. To reduce the hight costs of development of new systems in these fields improved the design...... management techniques and a vast array of computer aided techniques are applied during design and testing stages. The paper present and discusses the research and development of a software tool for automated failure mode and effects analysis - FMEA - of hydraulic systems. The paper explains the underlying...

  7. Pressure Load Analysis during Severe Accidents for the Evaluation of Late Containment Failure in OPR-1000

    Energy Technology Data Exchange (ETDEWEB)

    Park, S. Y.; Ahn, K. I. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    The MAAP code is a system level computer code capable of performing integral analyses of potential severe accident progressions in nuclear power plants, whose main purpose is to support a level 2 probabilistic safety assessment or severe accident management strategy developments. The code employs lots of user-options for supporting a sensitivity and uncertainty analysis. The present application is mainly focused on determining an estimate of the containment building pressure load caused by severe accident sequences. Key modeling parameters and phenomenological models employed for the present uncertainty analysis are closely related to in-vessel hydrogen generation, gas combustion in the containment, corium distribution in the containment after a reactor vessel failure, corium coolability in the reactor cavity, and molten-corium interaction with concrete. The phenomenology of severe accidents is extremely complex. In this paper, a sampling-based phenomenological uncertainty analysis was performed to statistically quantify uncertainties associated with the pressure load of a containment building for a late containment failure evaluation, based on the key modeling parameters employed in the MAAP code and random samples for those parameters. Phenomenological issues surrounding the late containment failure mode are highly complex. Included are the pressurization owing to steam generation in the cavity, molten corium-concrete interaction, late hydrogen burn in the containment, and the secondary heat removal availability. The methodology and calculation results can be applied for the optimum assessment of a late containment failure model. The accident sequences considered were a loss of coolant accidents and loss of offsite accidents expected in the OPR-1000 plant. As a result, uncertainties addressed in the pressure load of the containment building were quantified as a function of time. A realistic evaluation of the mean and variance estimates provides a more complete

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

    Science.gov (United States)

    Bittencourt, Hugo Souza; dos Reis, Helena França Correia; Lima, Melissa Santos; Gomes Neto, Mansueto

    2017-01-01

    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. PMID:28099587

  9. Premature ovarian failure (POF) syndrome: towards the molecular clinical analysis of its genetic complexity.

    Science.gov (United States)

    Fassnacht, W; Mempel, A; Strowitzki, T; Vogt, P H

    2006-01-01

    The Premature Ovarian Failure (POF) syndrome is a very heterogeneous clinical disorder due probably to the complex genetic networks controlling human folliculogenesis. Clinical subgroups of POF patients whose aetiology of ovarian failure is based on the same genetic factors are therefore difficult to establish. Some experimental evidence suggests that these genes might be clustered on the female sex chromosome in the POF1 and POF2 loci. This review is aimed to present an overview of the actual structural changes of the X chromosome causing POF, and to present a number of X and autosomal female fertility genes which are probably key genes in human folliculogenesis and are therefore prominent POF candidate genes. Towards the molecular analysis of their functional contribution to the genetic aetiology of POF in the clinic, an interdisciplinary scheme for their diagnostic analysis is presented in a pilot study focussed on chromosome analyses and the expression analysis of some major POF candidate genes (DAZL, DBX, FOXL2, INHalpha, GDF9, USP9X) in the leukocytes of 101 POF patients. It starts with a comprehensive and significantly improved clinical diagnostic program for this large and heterogeneous patient group.

  10. Failure analysis of an aluminum alloy material framework component induced by casting defects

    Science.gov (United States)

    Li, Bo; Hu, Weiye

    2017-09-01

    Failure analysis on a fractured radome framework component was carried out through visual observations, metallographic examination using optical microscope, fractog-raphy inspections using scanning electron microscope and chemical composition analysis. The failed frame was made of casting Al–Si7–Mg0.4 aluminum alloy. It had suffered a former vi-bration performance tests. It was indicated that the fractures were attributed to fatigue cracks which were induced by casting porosities at the outer surfaces of frame. Failure analysis was carefully conducted for the semi-penetrating crack appearing on the framework. According to the fractography inspected by scanning electron microscope, it was indicated that numerous casting porosities at the outer surface of the framework played the role of multiple fracture sources due to some applied stresses. Optical microstructure observations suggested that the dendrite-shaped casting porosities largely contributed to the crack-initiation. The groove-shaped structure at roots of spatial convex-bodies on the edge of casting porosities supplied the preferred paths of the crack-propagation. Besides, the brittle silicon eutectic particles distrib-uting along grain boundaries induced the intergranular fracture mode in the region of the over-load final fracture surface.

  11. How to make the most of failure mode and effect analysis.

    Science.gov (United States)

    Stalhandske, Erik; DeRosier, Joseph; Patail, Bryanne; Gosbee, John

    2003-01-01

    Current accreditation standards issued by the Joint Commission for the Accreditation of Healthcare Organizations (JCAHO) require hospitals to carry out a proactive risk assessment on at least 1 high-risk activity each year for each accredited program. Because hospital risk managers and patient safety managers generally do not have the knowledge or level of comfort for conducting a proactive risk assessment, they will appreciate the expertise offered by biomedical equipment technicians (BMETs), occupational safety and health professionals, and others. The skills that have been developed by BMETs and others while conducting job safety analyses or failure mode effect analysis can now be applied to a health care proactive analysis. This article touches on the Health Care Failure Mode and Effect Analysis (HFMEA) model that the Department of Veterans Affairs (VA) National Center for Patient Safety developed for proactive risk assessment within the health care community. The goal of this article is to enlighten BMETs and others on the growth of proactive risk assessment within health care and also on the support documents and materials produced by the VA. For additional information on HFMEA, visit the VA website at www.patientsafety.gov/HFMEA.html.

  12. Estimation of failure criteria in multivariate sensory shelf life testing using survival analysis.

    Science.gov (United States)

    Giménez, Ana; Gagliardi, Andrés; Ares, Gastón

    2017-09-01

    For most food products, shelf life is determined by changes in their sensory characteristics. A predetermined increase or decrease in the intensity of a sensory characteristic has frequently been used to signal that a product has reached the end of its shelf life. Considering all attributes change simultaneously, the concept of multivariate shelf life allows a single measurement of deterioration that takes into account all these sensory changes at a certain storage time. The aim of the present work was to apply survival analysis to estimate failure criteria in multivariate sensory shelf life testing using two case studies, hamburger buns and orange juice, by modelling the relationship between consumers' rejection of the product and the deterioration index estimated using PCA. In both studies, a panel of 13 trained assessors evaluated the samples using descriptive analysis whereas a panel of 100 consumers answered a "yes" or "no" question regarding intention to buy or consume the product. PC1 explained the great majority of the variance, indicating all sensory characteristics evolved similarly with storage time. Thus, PC1 could be regarded as index of sensory deterioration and a single failure criterion could be estimated through survival analysis for 25 and 50% consumers' rejection. The proposed approach based on multivariate shelf life testing may increase the accuracy of shelf life estimations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Weibull-Based Parts Failure Analysis Computer Program User’s Manual

    Science.gov (United States)

    1989-01-25

    and ETA are based on (required) 4) Estimated value of time to first failure (This value has no effect on the calculations) (optional) Output data: 1...Confidence interval (range) for time to first failure 2) Estimated value of time to first failure (same as 4 above) A quick estimate of time to first...NUMBER OF FAILURES BETA AND ETA ARE BASED ON IS : 4 ESTIMATED (CALCULATED) VALUE OF TIME TO FIRST FAILURE IS : 6000 FIGURE 27: CNFIN INTERVAL CALCULATION

  14. Analysis and dynamic modeling of a moraine failure and glacier lake outburst flood at Ventisquero Negro, Patagonian Andes (Argentina)

    Science.gov (United States)

    Worni, Raphael; Stoffel, Markus; Huggel, Christian; Volz, Christian; Casteller, Alejandro; Luckman, Brian

    2012-06-01

    SummaryAlthough moraine dams are inherently prone to failure because of their often weak structure, loose internal composition and lack of an engineered spillway, the understanding of dam breaching processes remains largely incomplete and appropriate modeling approaches are scarce. This paper analyzes a recent glacier lake outburst, caused by the failure of the terminal moraine of Ventisquero Negro (Patagonian Andes, Argentina) in May 2009. The dam breach trigger, breaching and lake emptying processes, plus the dynamics of the outburst flood were reconstructed based on field evidence and the application of a dynamic dam break model. Results indicate that the moraine failure was caused most probably by a rising lake level due to heavy precipitation, resulting in high lake outflow which led to dam erosion and finally to dam failure. The lake volume of ca. 10 × 106 m3 was released in ca. 3 h, producing high-discharge (ca. 4100 m3 s-1) debris flows and hyperconcentrated flows as the escaping water entrained large volumes of clastic material. The methodology presented in this paper provides valuable insights into complex dam breach and GLOF processes, and closes a critical gap in dynamic dam break modeling aimed at providing the lake outburst hydrograph. An accurate determination of outburst hydrographs constitutes one of the most crucial aspects for hazard assessment of unstable lakes and will gain further importance with ongoing glacier retreat and glacier lake formation.

  15. Hierarchical models for failure analysis of plates bent by distributed and localized transverse loadings

    Institute of Scientific and Technical Information of China (English)

    Erasmo CARRERA; Gaetano GIUNTA

    2008-01-01

    The failure analysis of simply supported, isotropic, square plates is addressed. Attention focuses on minimum failure load amplitudes and failure locations, von Mises' equivalent stress along the plate thickness is also addressed. Several distributed and localized loading conditions are considered. Loads act on the top of the plate. Bi-sinusoidal and uniform loads are taken into account for distributed loadings, while stepwise constant centric and off-centric loadings are addressed in the case of localized loadings. Analysis is performed considering plates whose length-to-thickness ratio a/h can be as high as 100 (thin plates) and as low as 2 (very thick plates). Results are obtained via several 2D plate models. Classical theories (CTs) and higher order models are applied. Those theories are based on polynomial approximation of the displacement field. Among the higher order theories (HOTs), HOTsd models account for the transverse shear deformations, while HOTs models account for both transverse shear and transverse normal deformations. LHOTs represent a local application of the higher order theories. A layerwise approach is thus assumed: by means of mathematical interfaces, the plate is considered to be made of several fictitious layers. The exact 3D solution is presented in order to determine the accuracy of the results obtained via the 2D models. In this way a hierarchy among the 2D theories is established. CTs provide highly accurate results for a/h greater than 10 in the case of distributed loadings and greater than 20 for localized Ioadings. Results obtained via HOTs are highly accurate in the case of very thick plates for bi-sinusoidal and centric loadings. In the case of uniform and off-centric loadings a high gradient is present in the neighborhood of the plate top. In those cases, LHOTs yield results that match the exact solution.

  16. Mechanical strength, fatigue life, and failure analysis of two prototypes and five conventional tibial locking screws.

    Science.gov (United States)

    Hou, Sheng-Mou; Wang, Jaw-Lin; Lin, Jinn

    2002-01-01

    To investigate the effects of the design and microstructure on the mechanical strength of tibial locking devices. The mechanical strength of two prototypes of specially developed locking devices (a both-ends-threaded screw and an unthreaded bolt) was tested and compared with that of five types of commercially available tibial locking screws (Synthes, Howmedica, Richards, Osteo AG, and Zimmer) with similar dimensions. The devices were inserted into a polyethylene tube and loaded at their midpoint by a materials testing machine to simulate a three-point bending test. Single-loading yielding strength and cyclic-loading fatigue life were then measured. Failure analysis of the fractured screws was performed to investigate the microstructure and potential causes of the fatigue fracture. Test results showed that both yielding strength and fatigue life were closely related to the section modulus of the inner diameter of screws. Among the threaded screws, the both-ends-threaded screws had a higher yielding strength and longer fatigue life than the Osteo AG, Howmedica, Richards, and Zimmer screws. The unthreaded bolts had a lower yielding strength than Synthes screws, but they demonstrated the longest fatigue life among all. In failure analysis of broken screws, no metallurgical or manufacturing defects were found except for surface microimperfections. The implants investigated in this study are manufactured with high-quality materials and manufacturing processes. The main cause of hardware failure was mechanical overloading. The five commercially used tibial locking screws had a relatively short fatigue life under high loading. Removing the screw threads might substantially increase the fatigue life of the locking devices. In unthreaded bolts, this increase might be tenfold to a hundredfold.

  17. Incident learning and failure-mode-and-effects-analysis guided safety initiatives in radiation medicine

    Directory of Open Access Journals (Sweden)

    Ajay eKapur

    2013-12-01

    Full Text Available By combining incident learning and process failure-mode-and-effects-analysis in a structure-process-outcome framework we have created a risk profile for our radiation medicine practice and implemented evidence-based risk mitigation initiatives focused on patient safety. Based on reactive reviews of incidents reported in our departmental incident-reporting system and proactive failure-mode-and-effects-analysis, high safety-risk procedures in our paperless radiation medicine process and latent risk factors were identified. Six initiatives aimed at the mitigation of associated severity, likelihood of occurrence and detectability risks were implemented. These were the standardization of care pathways and toxicity grading, pre-treatment-planning peer review, a policy to thwart delay-rushed processes, an electronic whiteboard to enhance coordination and the use of six-sigma metrics to monitor operational efficiencies. The effectiveness of these initiatives over a three year period was assessed using process and outcome specific metrics within the framework of the department structure. There has been a 47% increase in incident reporting, with no increase in adverse events. Care pathways have been used with greater than 97% clinical compliance rate. The implementation of peer review prior to treatment planning and use of the whiteboard have provided opportunities for proactive detection and correction of errors. There has been a twofold drop in the occurrence of high-risk procedural delays. Patient treatment start delays are routinely enforced on cases that would have historically been rushed. Z-scores for high risk procedures have steadily improved from 1.78 to 2.35. The initiatives resulted in sustained reductions of failure-mode risks as measured by a set of evidence-based metrics over a three year period. These augment or incorporate many of the published recommendations for patient safety in radiation medicine by translating them to clinical

  18. Analysis of Renal Artery Stenosis in Patients with Heart Failure: A RASHEF Study

    Institute of Scientific and Technical Information of China (English)

    Bin Zheng; Qin Ma; Li-Hong Zheng; Qiang Yong; Yi-Hua He; Jing-Hua Liu

    2015-01-01

    Background:Previous data are controversial about the association of renal artery stenosis (RAS) with clinical outcome in patients with heart failure.Definition of RAS in previous studies might not be appropriate.By definition of RAS with renal duplex sonography,we investigated the association of RAS with clinical outcome in patients with heart failure.Methods:In this retrospective study,we identified 164 patients with heart failure (New York Heart Association classification ≥Ⅱ;left ventricular ejection fraction <50%) who had received renal duplex sonography during hospital stay.RAS was defined as renal-aortic ratio ≥3.5 or a peak systolic velocity ≥200 cm/s (or both),or occlusion of the renal artery.Categorical data of patients were compared using the Chi-square test or Fisher's exact test.Cox proportional hazards regression modeling technique was used to investigate the prognostic significance of possible predictors.Results:Finally,143 patients were enrolled.Median follow-up time was 32 months (1-53 months).Twenty-two patients were diagnosed as RAS by renal duplex sonography,including 13 unilateral RAS (3 left RAS,10 right RAS) and 9 bilateral RAS.There were more all-cause mortality and cardiovascular death in patients with RAS than patients without RAS.By multivariate analysis,RAS was a significant predictor for all-cause death and cardiovascular death (hazard ratio [HR] =4.155,95% confidence interval [CI]:1.546-11.164,P =0.005;and HR =3.483,95% CI:1.200-10.104,P =0.022,respectively).As for composite endpoint events,including death,nonfatal myocardial infarction,ischemic stroke or intracranial hemorrhage,rehospitalization for cardiac failure,and renal replacement therapy,only angiotensin-converting enzyme inhibitor or angiotensin-receptor blocker was significant predictor.RAS was not a significant predictor for composite endpoint events.Conclusions:Our data suggested that RAS is associated with a poorer clinical outcome in patients with heart

  19. Use of failure mode effect analysis (FMEA) to improve medication management process.

    Science.gov (United States)

    Jain, Khushboo

    2017-03-13

    Purpose Medication management is a complex process, at high risk of error with life threatening consequences. The focus should be on devising strategies to avoid errors and make the process self-reliable by ensuring prevention of errors and/or error detection at subsequent stages. The purpose of this paper is to use failure mode effect analysis (FMEA), a systematic proactive tool, to identify the likelihood and the causes for the process to fail at various steps and prioritise them to devise risk reduction strategies to improve patient safety. Design/methodology/approach The study was designed as an observational analytical study of medication management process in the inpatient area of a multi-speciality hospital in Gurgaon, Haryana, India. A team was made to study the complex process of medication management in the hospital. FMEA tool was used. Corrective actions were developed based on the prioritised failure modes which were implemented and monitored. Findings The percentage distribution of medication errors as per the observation made by the team was found to be maximum of transcription errors (37 per cent) followed by administration errors (29 per cent) indicating the need to identify the causes and effects of their occurrence. In all, 11 failure modes were identified out of which major five were prioritised based on the risk priority number (RPN). The process was repeated after corrective actions were taken which resulted in about 40 per cent (average) and around 60 per cent reduction in the RPN of prioritised failure modes. Research limitations/implications FMEA is a time consuming process and requires a multidisciplinary team which has good understanding of the process being analysed. FMEA only helps in identifying the possibilities of a process to fail, it does not eliminate them, additional efforts are required to develop action plans and implement them. Frank discussion and agreement among the team members is required not only for successfully conducing

  20. Time-to-event analysis of individual variables associated with nursing students' academic failure: a longitudinal study.

    Science.gov (United States)

    Dante, Angelo; Fabris, Stefano; Palese, Alvisa

    2013-12-01

    Empirical studies and conceptual frameworks presented in the extant literature offer a static imagining of academic failure. Time-to-event analysis, which captures the dynamism of individual factors, as when they determine the failure to properly tailor timely strategies, impose longitudinal studies which are still lacking within the field. The aims of this longitudinal study were to investigate the time which elapses from a nursing student's admission to a Bachelor of Nursing program to their academic failure and to estimate the predictive power of individual variables on academic failure. Enrolled students (n = 170) in two Italian nursing degree programs during academic year 2008-2009, received at the beginning of each years a questionnaire which evaluated individual variables. Academic failure rate was 37.2 %. Time-to-event analysis has shown that academic failure occurred after an average of 664.52 days of course attendance ((95 %)CI = 623.2-705.8). Kaplan-Meier analyses demonstrated a high likelihood of failure among males (χ(2) 7.790, p 0.005) and among those who had obtained a final average grade in their secondary education ≤73/100 (χ(2)11.676, p 0.001). Cox regression analysis confirmed an increased likelihood of failure over time among males as compared to females (HR 1.931, (95 %)CI = 1.017-3.670), and among students living more than a 30 min commute from their place of study (HR 1.898, (95 %)CI = 1.015-3.547). The effect of these two factors on academic failure has been seen to manifest primarily toward the end of students' second academic year; students at risk might be supported by the appropriate university staff prior to this period.

  1. Reliability analysis of supporting pressure in tunnels based on three-dimensional failure mechanism

    Institute of Scientific and Technical Information of China (English)

    罗卫华; 李闻韬

    2016-01-01

    Based on nonlinear failure criterion, a three-dimensional failure mechanism of the possible collapse of deep tunnel is presented with limit analysis theory. Support pressure is taken into consideration in the virtual work equation performed under the upper bound theorem. It is necessary to point out that the properties of surrounding rock mass plays a vital role in the shape of collapsing rock mass. The first order reliability method and Monte Carlo simulation method are then employed to analyze the stability of presented mechanism. Different rock parameters are considered random variables to value the corresponding reliability index with an increasing applied support pressure. The reliability indexes calculated by two methods are in good agreement. Sensitivity analysis was performed and the influence of coefficient variation of rock parameters was discussed. It is shown that the tensile strength plays a much more important role in reliability index than dimensionless parameter, and that small changes occurring in the coefficient of variation would make great influence of reliability index. Thus, significant attention should be paid to the properties of surrounding rock mass and the applied support pressure to maintain the stability of tunnel can be determined for a given reliability index.

  2. A critical analysis of the failure of nurses to raise concerns about poor patient care.

    Science.gov (United States)

    Roberts, Marc

    2016-10-28

    The occurrence of poor patient care is emerging as one of the most significant, challenging, and critical issues confronting contemporary nursing and those responsible for the provision of health care more generally. Indeed, as a consequence of the increased recognition of the manner in which nurses can be implicated in the occurrence of poor patient care, there has been sustained critical debate that seeks to understand how such healthcare failings can occur and, in particular, why nurses seemingly fail to intervene, raise concerns, and effectively respond to prevent the occurrence and continuation of such poor patient care. In seeking to contribute to this critical discussion, and in contrast to those "situational explanations" that maintain that the failure to raise concerns is a consequence of the contextual factors and challenging conditions to which nurses can be subject in the clinical setting, this paper will provide a resolutely philosophical analysis of that failure. In particular, it will draw upon the work of Jean-Paul Sartre-the French philosopher generally regarded as one of the most influential thinkers of the twentieth century-in order to propose that his work can be productively recontextualized to provide a detailed, challenging, and provocative critical analysis of the occurrence and continuation of poor patient care and the role of individual nurse practitioners in such healthcare failings.

  3. Reduced Data Dualscale Entropy Analysis of HRV Signals for Improved Congestive Heart Failure Detection

    Science.gov (United States)

    Kuntamalla, Srinivas; Lekkala, Ram Gopal Reddy

    2014-10-01

    Heart rate variability (HRV) is an important dynamic variable of the cardiovascular system, which operates on multiple time scales. In this study, Multiscale entropy (MSE) analysis is applied to HRV signals taken from Physiobank to discriminate Congestive Heart Failure (CHF) patients from healthy young and elderly subjects. The discrimination power of the MSE method is decreased as the amount of the data reduces and the lowest amount of the data at which there is a clear discrimination between CHF and normal subjects is found to be 4000 samples. Further, this method failed to discriminate CHF from healthy elderly subjects. In view of this, the Reduced Data Dualscale Entropy Analysis method is proposed to reduce the data size required (as low as 500 samples) for clearly discriminating the CHF patients from young and elderly subjects with only two scales. Further, an easy to interpret index is derived using this new approach for the diagnosis of CHF. This index shows 100 % accuracy and correlates well with the pathophysiology of heart failure.

  4. A failure mode effect analysis on extracorporeal circuits for cardiopulmonary bypass.

    Science.gov (United States)

    Wehrli-Veit, Michel; Riley, Jeffrey B; Austin, Jon W

    2004-12-01

    Although many refinements in perfusion methodology and devices have been made, extracorporeal circulation remains a contributor to neurological complications, bleeding coagulopathies, use of blood products, as well as systemic inflammatory response. With the exposure of these adverse effects of cardiopulmonary bypass, the necessity to re-examine the safety of extracorporeal circuits is vital. A failure mode effect analysis (FMEA) is a proven proactive technique developed to evaluate system effect or equipment failure. FMEA was used to evaluate the six different types of extracorporeal circuits based on feedback from five clinical experts. Cardiovascular device manufacturers, the Veteran's Administration National Center for Patient Safety, and the Joint Commission on Accreditation of Healthcare Organizations recommend the use of FMEA to assess and manage risks in current and developing technologies and therapies. This analysis investigates the safety of six types of extracorporeal circuits used in coronary revascularization, including the newer miniaturized extracorporeal circuits. The FMEA lists and ranks the hazards associated with the use of each cardiopulmonary bypass extracorporeal circuit type. To increase the safety of extracorporeal circuits and minimize the effects associated with cardiopulmonary bypass, perfusionists must incorporate FMEA into their clinical practice.

  5. Failure Mode Analysis Of Torsion Shaft In Garrett-5 Engine Using Two Test Pieces

    Directory of Open Access Journals (Sweden)

    Rio Melvin Aro. T

    2014-08-01

    Full Text Available This work deals with “Failure Analysis of Internal splines in Torsion Shaft” of “TPE 331-5-252D - GARRET ENGINE” which is used in Dornier aircraft. Garret Engine is a type of air breathing engine. It comes under the category of Turboprop engines of Gas turbine engine. As separate shafts are used for propeller and turbine, this aids them to rotate at different RPM. A torsion shaft is used to transmit the torque from main shaft to propeller shaft. Torsion shaft is used to give a deflection which is also used to measure the torque of the engine. This torsion shaft is internally connected with the main power transmission shaft and its other end is coupled to a coupler shaft with engagement of its internal splines to the external splines of coupler shaft. Further this coupler connects to the gearing system and transmits power to the propeller shaft. Due to Continues variable load over internal splines, it is subjected to high rate of wear and tear. This problem can be rectified by Failure Mode Analysis Method, in which heat treatment process of torsion shaft is being carried out. Two test pieces are heat treated separately at different temperatures of 5800C and 5400C at variable time durations. Tuffriding which is a Liquid nitriding process is done with this two test pieces and results are analyzed. The hardness of the material is increased to desired values and its life time is also increased which overcomes the problem.

  6. Risk management for outsourcing biomedical waste disposal – Using the failure mode and effects analysis

    Energy Technology Data Exchange (ETDEWEB)

    Liao, Ching-Jong; Ho, Chao Chung, E-mail: ho919@pchome.com.tw

    2014-07-15

    Highlights: • This study is based on a real case in hospital in Taiwan. • We use Failure Mode and Effects Analysis (FMEA) as the evaluation method. • We successfully identify the evaluation factors of bio-medical waste disposal risk. - Abstract: Using the failure mode and effects analysis, this study examined biomedical waste companies through risk assessment. Moreover, it evaluated the supervisors of biomedical waste units in hospitals, and factors relating to the outsourcing risk assessment of biomedical waste in hospitals by referring to waste disposal acts. An expert questionnaire survey was conducted on the personnel involved in waste disposal units in hospitals, in order to identify important factors relating to the outsourcing risk of biomedical waste in hospitals. This study calculated the risk priority number (RPN) and selected items with an RPN value higher than 80 for improvement. These items included “availability of freezing devices”, “availability of containers for sharp items”, “disposal frequency”, “disposal volume”, “disposal method”, “vehicles meeting the regulations”, and “declaration of three lists”. This study also aimed to identify important selection factors of biomedical waste disposal companies by hospitals in terms of risk. These findings can serve as references for hospitals in the selection of outsourcing companies for biomedical waste disposal.

  7. Heart Failure Care in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

    Science.gov (United States)

    Callender, Thomas; Woodward, Mark; Roth, Gregory; Farzadfar, Farshad; Lemarie, Jean-Christophe; Gicquel, Stéphanie; Atherton, John; Rahimzadeh, Shadi; Ghaziani, Mehdi; Shaikh, Maaz; Bennett, Derrick; Patel, Anushka; Lam, Carolyn S. P.; Sliwa, Karen; Barretto, Antonio; Siswanto, Bambang Budi; Diaz, Alejandro; Herpin, Daniel; Krum, Henry; Eliasz, Thomas; Forbes, Anna; Kiszely, Alastair; Khosla, Rajit; Petrinic, Tatjana; Praveen, Devarsetty; Shrivastava, Roohi; Xin, Du; MacMahon, Stephen; McMurray, John; Rahimi, Kazem

    2014-01-01

    failure vary substantially across LMICs. On average, the use of evidence-based medications tends to be suboptimal. Better strategies for heart failure surveillance and management in LMICs are needed. Please see later in the article for the Editors' Summary PMID:25117081

  8. SU-E-T-627: Failure Modes and Effect Analysis for Monthly Quality Assurance of Linear Accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Xie, J [Fudan University shanghai cancer center, Shanghai, Shanghai (China); Xiao, Y [Thomas Jefferson UniversityHospital, Philadelphia, PA (United States); Wang, J; Peng, J; Lu, S [Fudan University Shanghai Cancer Center, Shanghai, Shanghai (China); Hu, W [Fudan University Shanghai Caner Center, Shanghai, Shanghai (China)

    2014-06-15

    Purpose: To develop and implement a failure mode and effect analysis (FMEA) on routine monthly Quality Assurance (QA) tests (physical tests part) of linear accelerator. Methods: A systematic failure mode and effect analysis method was performed for monthly QA procedures. A detailed process tree of monthly QA was created and potential failure modes were defined. Each failure mode may have many influencing factors. For each factor, a risk probability number (RPN) was calculated from the product of probability of occurrence (O), the severity of effect (S), and detectability of the failure (D). The RPN scores are in a range of 1 to 1000, with higher scores indicating stronger correlation to a given influencing factor of a failure mode. Five medical physicists in our institution were responsible to discuss and to define the O, S, D values. Results: 15 possible failure modes were identified and all RPN scores of all influencing factors of these 15 failue modes were from 8 to 150, and the checklist of FMEA in monthly QA was drawn. The system showed consistent and accurate response to erroneous conditions. Conclusion: The influencing factors of RPN greater than 50 were considered as highly-correlated factors of a certain out-oftolerance monthly QA test. FMEA is a fast and flexible tool to develop an implement a quality management (QM) frame work of monthly QA, which improved the QA efficiency of our QA team. The FMEA work may incorporate more quantification and monitoring fuctions in future.

  9. Survey Summary

    Data.gov (United States)

    U.S. Department of Health & Human Services — Nursing home summary information for the Health and Fire Safety Inspections currently listed on Nursing Home Compare, including dates of the three most recent...

  10. Meteorological Summaries

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Multi-year summaries of one or more meteorological elements at a station or in a state. Primarily includes Form 1078, a United States Weather Bureau form designed...

  11. Executive Summary

    DEFF Research Database (Denmark)

    Katritsis, Demosthenes G; Boriani, Giuseppe; Cosio, Francisco G

    2016-01-01

    This paper is an executive summary of the full European Heart Rhythm Association (EHRA) consensus document on the management of supraventricular arrhythmias, published in Europace. It summarises developments in the field and provides recommendations for patient management, with particular emphasi...

  12. Characterization and Failure Analysis of Ceramic Filters Utilized for Emission Control Coal Gasification

    Energy Technology Data Exchange (ETDEWEB)

    Daniel Mei; Jianren Zhou; Ziaul Huque

    1998-03-01

    Advanced integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) power system requires both hot gas desulfurization and particulate filtration to improve system thermal efficiency and overall performance. Therefore, effective high temperature ceramic filters are indispensable key component in both of the advanced IGCC and PFBC coal based power systems to perform hot gas cleanup work. To meet the environmental particulate emission requirements and improve thermal efficiency, ceramic filters are mainly utilized to cleanup the hot gas particulate to protect downstream heat exchanger and gas turbine components from fouling and corrosion. The mechanical integrity of ceramic filters and an efficient dust cake removal system are the key issues for hot gas cleanup systems. The filters must survive combined stresses due to mechanical, thermal, chemical and steam attack throughout normal operations (cold back pulse cleaning jets), unexpected excessive ash accumulation, and the start up and shut down conditions. To evaluate the design and performance of ceramic filters, different long term filter testing programs were conducted. To fulfill this purpose, two Advanced Particle Filter (APF) systems were complete at Tidd PFBC Demonstration Plant, in Brilliant, Ohio in late 1990 as part of the Department of Energy's (DOE) Clean Coal Technology Program. But the most undesirable thing ever happened was the sudden functional and physical failures of filters prior to its designed life time. In Tidd APF filter vessel, twenty eight (28) filters failed one time. Significant research effort has been carried out to find out the causes that led to the early failure of filters. In this work, the studies are emphasized on the possible failure causes analysis of rigid ceramic candle filters. The objectives of this program were to provide an systematic study on the characterization of filters, material laboratory analysis on filter micro-structure, the

  13. Failure analysis of satellite subsystems to define suitable de-orbit devices

    Science.gov (United States)

    Palla, Chiara; Peroni, Moreno; Kingston, Jennifer

    2016-11-01

    Space missions in Low Earth Orbit (LEO) are severely affected by the build-up of orbital debris. A key practice, to be compliant with IADC (Inter-Agency Space Debris Coordination Committee) mitigation guidelines, is the removal of space systems that interfere with the LEO region not later than 25 years after the End of Mission. It is important to note that the current guidelines are not generally legally binding, even if different Space Agencies are now looking at the compliance for their missions. If the guidelines will change in law, it will be mandatory to have a postmission disposal strategy for all satellites, including micro and smaller classes. A potential increased number of these satellites is confirmed by different projections, in particular in the commercial sector. Micro and smaller spacecraft are, in general, not provided with propulsion capabilities to achieve a controlled re-entry, so they need different de-orbit disposal methods. When considering the utility of different debris mitigation methods, it is useful to understand which spacecraft subsystems are most likely to fail and how this may affect the operation of a de-orbit system. This also helps the consideration of which components are the most relevant or should be redundant depending on the satellite mass class. This work is based on a sample of LEO and MEO satellites launched between January 2000 and December 2014 with mass lower than 1000 kg. Failure analysis of satellite subsystems is performed by means of the Kaplan-Meier survival analysis; the parametric fits are conducted with Weibull distributions. The study is carried out by using the satellite database SpaceTrak™ which provides anomalies, failures, and trends information for spacecraft subsystems and launch vehicles. The database identifies five states for each satellite subsystem: three degraded states, one fully operational state, and one failed state (complete failure). The results obtained can guide the identification of the

  14. RELIABILITY ANALYSIS FOR A REPAIRABLE PARALLEL SYSTEM WITH TIME-VARYING FAILURE RATES

    Institute of Scientific and Technical Information of China (English)

    TangShengdao; WangFengquan

    2005-01-01

    To solve a real problem :how to calculate the reliability of a system with time-varying failure rates in industry systems,this paper studies a model for the load-sharing parallel system with time-varying failure rates,and obtains calculating formulas of reliability and availability of the system by solving differential equations. In this paper, the failure rates are expressed in polynomial configuration. The constant,linear and Weibull failure rate are in their special form. The polynomial failure rates provide flexibility in modeling the practical time-varying failure rates.

  15. 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 anemia, and CRF demonstrated that each one was an independent predictor for the presence of the others. These findings point to the presence of cardio-renal-anemia syndrome and the necessity of treating these comorbidities in patients with HF.

  16. Vulnerabilities to Rock-Slope Failure Impacts from Christchurch, NZ Case History Analysis

    Science.gov (United States)

    Grant, A.; Wartman, J.; Massey, C. I.; Olsen, M. J.; Motley, M. R.; Hanson, D.; Henderson, J.

    2015-12-01

    Rock-slope failures during the 2010/11 Canterbury (Christchurch), New Zealand Earthquake Sequence resulted in 5 fatalities and caused an estimated US$400 million of damage to buildings and infrastructure. Reducing losses from rock-slope failures requires consideration of both hazard (i.e. likelihood of occurrence) and risk (i.e. likelihood of losses given an occurrence). Risk assessment thus requires information on the vulnerability of structures to rock or boulder impacts. Here we present 32 case histories of structures impacted by boulders triggered during the 2010/11 Canterbury earthquake sequence, in the Port Hills region of Christchurch, New Zealand. The consequences of rock fall impacts on structures, taken as penetration distance into structures, are shown to follow a power-law distribution with impact energy. Detailed mapping of rock fall sources and paths from field mapping, aerial lidar digital elevation model (DEM) data, and high-resolution aerial imagery produced 32 well-constrained runout paths of boulders that impacted structures. Impact velocities used for structural analysis were developed using lumped mass 2-D rock fall runout models using 1-m resolution lidar elevation data. Model inputs were based on calibrated surface parameters from mapped runout paths of 198 additional boulder runouts. Terrestrial lidar scans and structure from motion (SfM) imagery generated 3-D point cloud data used to measure structural damage and impacting boulders. Combining velocity distributions from 2-D analysis and high-precision boulder dimensions, kinetic energy distributions were calculated for all impacts. Calculated impact energy versus penetration distance for all cases suggests a power-law relationship between damage and impact energy. These case histories and resulting fragility curve should serve as a foundation for future risk analysis of rock fall hazards by linking vulnerability data to the predicted energy distributions from the hazard analysis.

  17. Direct Torque Control in presence of Current sensor failure in Variable Speed Wind System: Effect analysis, detection and control reconfiguration

    Directory of Open Access Journals (Sweden)

    A. J. Arbi

    2008-03-01

    Full Text Available This paper presents a study of current sensor failure in a Direct Torque Control applied to a Double Fed Induction Generator based Variable Speed Wind System. The effect of scaling and offset current sensor errors is discussed through sensibility analysis. A control reconfiguration is then proposed to remedy this sensor failure. Simulation results emphasize the good performances of the proposed current sensor fault tolerant control

  18. Analysis of scale effect in compressive ice failure and implications for design

    Science.gov (United States)

    Taylor, Rocky Scott

    The main focus of the study was the analysis of scale effect in local ice pressure resulting from probabilistic (spalling) fracture and the relationship between local and global loads due to the averaging of pressures across the width of a structure. A review of fundamental theory, relevant ice mechanics and a critical analysis of data and theory related to the scale dependent pressure behavior of ice were completed. To study high pressure zones (hpzs), data from small-scale indentation tests carried out at the NRC-IOT were analyzed, including small-scale ice block and ice sheet tests. Finite element analysis was used to model a sample ice block indentation event using a damaging, viscoelastic material model and element removal techniques (for spalling). Medium scale tactile sensor data from the Japan Ocean Industries Association (JOIA) program were analyzed to study details of hpz behavior. The averaging of non-simultaneous hpz loads during an ice-structure interaction was examined using local panel pressure data. Probabilistic averaging methodology for extrapolating full-scale pressures from local panel pressures was studied and an improved correlation model was formulated. Panel correlations for high speed events were observed to be lower than panel correlations for low speed events. Global pressure estimates based on probabilistic averaging were found to give substantially lower average errors in estimation of load compared with methods based on linear extrapolation (no averaging). Panel correlations were analyzed for Molikpaq and compared with JOIA results. From this analysis, it was shown that averaging does result in decreasing pressure for increasing structure width. The relationship between local pressure and ice thickness for a panel of unit width was studied in detail using full-scale data from the STRICE, Molikpaq, Cook Inlet and Japan Ocean Industries Association (JOIA) data sets. A distinct trend of decreasing pressure with increasing ice thickness

  19. Dam failure analysis for the Lago de Matrullas Dam, Orocovis, Puerto Rico

    Science.gov (United States)

    Torres-Sierra, Heriberto; Gómez-Fragoso, Julieta

    2015-01-01

    The U.S. Geological Survey, in cooperation with the Puerto Rico Electric Power Authority, completed a hydrologic and hydraulic study to assess the potential hazard to human life and property associated with the hypothetical failure of the Lago de Matrullas Dam, located within the headwaters of the Río Grande de Manatí. The hydrologic study yielded outflow hydrographs and peak discharges for Lago de Matrullas and other subbasins in the Río Grande de Manatí hydrographic basin for three extreme rainfall events: (1) a 6-hour probable maximum precipitation (PMP) event, (2) a 24-hour PMP event, and (3) a 100-year-recurrence, 24-hour rainfall event. The hydraulic study simulated the hypothetical dam failure of Lago de Matrullas using hypothetical flood hydrographs generated from the hydrologic study and selected dam breach parameters. The flood wave resulting from the failure was downstream-routed through the lower reaches of the Río Matrullas, the Río Toro Negro, and the Río Grande de Manatí for determination of water-surface profiles developed from the event-based hydrologic scenarios and “sunny day” (no precipitation) conditions. The Hydrologic Modeling System (HEC–HMS) and the River Analysis System (HEC–RAS) computer programs, developed by the Hydrologic Engineering Center (HEC) of the U.S. Army Corps of Engineers, were used for the hydrologic and hydraulic modeling, respectively. The flow routing in the hydraulic analyses was performed using the unsteady-state flow module available in the HEC–RAS model.

  20. Mission analysis of photovoltaic solar energy systems. Final report. Volume I. Summary

    Energy Technology Data Exchange (ETDEWEB)

    1975-12-01

    A summary report of a study program whose principal objective was to develop methods for the technical and economic evaluation of potential missions (applications) for photovoltaic solar energy conversion in the southwestern United States in the 1980 to 2000 period is presented. A secondary objective was to apply the methodology, when developed, to the evaluation of a number of illustrative examples of candidate missions in order to obtain at least a preliminary indication of the competitive position of the photovoltaic technology in the future energy economy of the Southwest. Because of their large potential significance, most of the effort in the study was devoted to two main classes of missions: on-site applications (in which the photovoltaic system serves an electric load point that is colocated with the system) and central station power plant applications. A smaller amount of attention was given to the electrolytic production of hydrogen with electric power generated by the photovoltaic conversion of solar energy. (WHK)

  1. Diagnostic prediction of renal failure from blood serum analysis by FTIR spectrometry and chemometrics

    Science.gov (United States)

    Khanmohammadi, Mohammdreza; Ghasemi, Keyvan; Garmarudi, Amir Bagheri; Ramin, Mehdi

    2015-02-01

    A new diagnostic approach based on Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectrometry and classification algorithm has been introduced which provides a rapid, reliable, and easy way to perform blood test for the diagnosis of renal failure. Blood serum samples from 35 renal failure patients and 40 healthy persons were analyzed by ATR-FTIR spectrometry. The resulting data was processed by Quadratic Discriminant Analysis (QDA) and QDA combined with simple filtered method. Spectroscopic studies were performed in 900-2000 cm-1 spectral region with 3.85 cm-1 data space. Results showed 93.33% and 100% of accuracy for QDA and filter-QDA models, respectively. In the first step, 30 samples were applied to construct the model. In order to modify the capability of QDA in prediction of test samples, filter-based feature selection methods were applied. It was found that the filtered spectra coupled with QDA could correctly predict the test samples in most of the cases.

  2. FUZZY ANALYSIS OF MACHINE REPAIR PROBLEM WITH SWITCHING FAILURE AND REBOOT

    Directory of Open Access Journals (Sweden)

    Chandra Shekhar

    2014-04-01

    Full Text Available Multi-component machining systems are being used in every sphere of engineering sector such as job shops, flow lines, communication system, computer system, etc. This paper presents fuzzy analysis of availability characteris tics of machining system comprising of multi- active units and multi-standby units. The Markov ma chine repair model has been developed by incorporating the concepts of switching failure and reboot. The life times of identical active units and identical standby units follow the fuzzified ex ponential distribution. The time-to-repair of failed unit is also governed by the fuzzified expon ential distribution. The automatic switching of standby unit to replace the failed units may not be perfect in many realistic scenarios as we assume the switching failure probability . The system may reboot itself automatically if the active unit fails and available standby unit is not able to replace the failed unit perfectly. We employ the parametric non-linear program with -cut approach to establish the membership function of availability of the system and availabi lity of both standbys. A numerical example is also provided to validate the suggested approach wh ich facilitates more useful information for the designers and practitioners to examine general repa irable system more accurately.

  3. Risk-Cost Estimation of On-Site Wastewater Treatment System Failures Using Extreme Value Analysis.

    Science.gov (United States)

    Kohler, Laura E; Silverstein, JoAnn; Rajagopalan, Balaji

    2017-05-01

      Owner resistance to increasing regulation of on-site wastewater treatment systems (OWTS), including obligatory inspections and upgrades, moratoriums and cease-and-desist orders in communities around the U.S. demonstrate the challenges associated with managing risks of inadequate performance of owner-operated wastewater treatment systems. As a result, determining appropriate and enforceable performance measures in an industry with little history of these requirements is challenging. To better support such measures, we develop a statistical method to predict lifetime failure risks, expressed as costs, in order to identify operational factors associated with costly repairs and replacement. A binomial logistic regression is used to fit data from public records of reported OWTS failures, in Boulder County, Colorado, which has 14 300 OWTS to determine the probability that an OWTS will be in a low- or high-risk category for lifetime repair and replacement costs. High-performing or low risk OWTS with repairs and replacements below the threshold of $9000 over a 40-year life are associated with more frequent inspections and upgrades following home additions. OWTS with a high risk of exceeding the repair cost threshold of $18 000 are further analyzed in a variation of extreme value analysis (EVA), Points Over Threshold (POT) where the distribution of risk-cost exceedance values are represented by a generalized Pareto distribution. The resulting threshold cost exceedance estimates for OWTS in the high-risk category over a 40-year expected life ranged from $18 000 to $44 000.

  4. 拖拉机故障分析与维修%Tractor Failure Analysis and Maintenance

    Institute of Scientific and Technical Information of China (English)

    何家潮

    2013-01-01

    The tractor is to have the largest number of agricultural machinery, one of the most versatile machines. The course of the tractor, as parts wear, variations and other reasons, causing decreased performance, affect normal use, ie a failure occurs tractor. Tractor out of the failure to timely repair, do not let the machine work sick, or small problems will cause major accidents, outweigh the benefits. Article mainly discusses the tractor fault repair analysis.%拖拉机是农业机械中拥有量最多、用途最广泛的机械之一。在拖拉机使用过程中,由于零件磨损,变型等原因,引起使用性能下降,影响正常使用,也就是说拖拉机产生了故障。拖拉机出了故障要及时进行修理,不能让机器带病作业,否则小毛病就会造成大事故,得不偿失。文章主要对拖拉机的故障维修进行探讨分析。

  5. 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.

  6. Practical Implementation of Failure Mode and Effects Analysis for Safety and Efficiency in Stereotactic Radiosurgery

    Energy Technology Data Exchange (ETDEWEB)

    Younge, Kelly Cooper, E-mail: kyounge@med.umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Wang, Yizhen [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Thompson, John; Giovinazzo, Julia; Finlay, Marisa [Department of Radiation Oncology, Trillium Health Partners - Credit Valley Hospital Site, Mississauga Halton/Central West Regional Cancer Program, Mississauga, ON (Canada); Sankreacha, Raxa [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States)

    2015-04-01

    Purpose: To improve the safety and efficiency of a new stereotactic radiosurgery program with the application of failure mode and effects analysis (FMEA) performed by a multidisciplinary team of health care professionals. Methods and Materials: Representatives included physicists, therapists, dosimetrists, oncologists, and administrators. A detailed process tree was created from an initial high-level process tree to facilitate the identification of possible failure modes. Group members were asked to determine failure modes that they considered to be the highest risk before scoring failure modes. Risk priority numbers (RPNs) were determined by each group member individually and then averaged. Results: A total of 99 failure modes were identified. The 5 failure modes with an RPN above 150 were further analyzed to attempt to reduce these RPNs. Only 1 of the initial items that the group presumed to be high-risk (magnetic resonance imaging laterality reversed) was ranked in these top 5 items. New process controls were put in place to reduce the severity, occurrence, and detectability scores for all of the top 5 failure modes. Conclusions: FMEA is a valuable team activity that can assist in the creation or restructuring of a quality assurance program with the aim of improved safety, quality, and efficiency. Performing the FMEA helped group members to see how they fit into the bigger picture of the program, and it served to reduce biases and preconceived notions about which elements of the program were the riskiest.

  7. Physical and chemical analysis of lithium-ion battery cell-to-cell failure events inside custom fire chamber

    Science.gov (United States)

    Spinner, Neil S.; Field, Christopher R.; Hammond, Mark H.; Williams, Bradley A.; Myers, Kristina M.; Lubrano, Adam L.; Rose-Pehrsson, Susan L.; Tuttle, Steven G.

    2015-04-01

    A 5-cubic meter decompression chamber was re-purposed as a fire test chamber to conduct failure and abuse experiments on lithium-ion batteries. Various modifications were performed to enable remote control and monitoring of chamber functions, along with collection of data from instrumentation during tests including high speed and infrared cameras, a Fourier transform infrared spectrometer, real-time gas analyzers, and compact reconfigurable input and output devices. Single- and multi-cell packages of LiCoO2 chemistry 18650 lithium-ion batteries were constructed and data was obtained and analyzed for abuse and failure tests. Surrogate 18650 cells were designed and fabricated for multi-cell packages that mimicked the thermal behavior of real cells without using any active components, enabling internal temperature monitoring of cells adjacent to the active cell undergoing failure. Heat propagation and video recordings before, during, and after energetic failure events revealed a high degree of heterogeneity; some batteries exhibited short burst of sparks while others experienced a longer, sustained flame during failure. Carbon monoxide, carbon dioxide, methane, dimethyl carbonate, and ethylene carbonate were detected via gas analysis, and the presence of these species was consistent throughout all failure events. These results highlight the inherent danger in large format lithium-ion battery packs with regards to cell-to-cell failure, and illustrate the need for effective safety features.

  8. 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

  9. Application of Design Failure Modes and Effect Analysis (DFMEA to Vertical Roller Mill Gearbox

    Directory of Open Access Journals (Sweden)

    Gaurav J. Pawar 1 ,

    2015-12-01

    Full Text Available Design FMEA is structured method of identifying potential failure modes and providing corrective actions before first production run occurs. This paper aims to provide probable causes of failure, levels of effects of failure and corrective actions to be taken in the design phase for BevelPlanetary Vertical Roller Mill Gearbox.

  10. Expert system for failure analysis of shafts; Sistema experto para analisis de falla de ejes

    Energy Technology Data Exchange (ETDEWEB)

    Jacobo Armendariz, V.H.; Cerrud Sanchez, S.M.; Ramirez Rodriguez, M.A.; Ortiz Prado, A. [Facultad de Ingenieria, UNAM, Mexico, D.F. (Mexico)

    2002-09-01

    An expert system for the failure analysis in metallic mechanical devices is being Developer at the Mechanical Engineering departments of the Faculty of Engineering of the Universidad Nacional Autonoma de Mexico (UNAM) to provide a solution for the failure analysis in cases where considerable experience in needed. The system pretends to resolve the scarceness of experts in the field of failure analysis and is oriented toward the metal-mechanics industry and will also have didactic applications. The main complication in the development of the system is the broad range of applications envisioned, like gears, shafts, bolts and springs between others. Therefore, it was decided to develop the system in a modular way, using the experience obtained in a first module to proceed faster in the others. The present paper presents the elaboration of the module that analyses shafts. This will serve as the base to expand the system toward other components. It uses the general structure of the global system, including an auxiliary software for the determination of maximum stresses in the corresponding parts. [Spanish] Con el fin de contar con un medio eficaz para la solucion de problemas relacionados con el analisis de falla, en donde la experiencia juega un papel fundamental, el Departamento de Ingenieria Mecanica de la Facultad de ingenieria de la Universidad Nacional Autonoma de Mexico (UNAM) , esta desarrollando el proyecto Sistema experto para analisis de falla de elementos mecanicos, dicho sistema busca resolver el inconveniente de la escasez de expertos y se orienta, tanto a la necesidad de la industria metalmecanica como a la de la docencia. Presenta tambien complicaciones en su desarrollo, ya que se pretende la posibilidad de realizar analisis de falla de elementos como ejes, engranes, pernos, bielas, resortes, tornillos etc. Por lo anterior, se establecio como estrategia el desarrollo del sistema por modulos, ya que teniendo la experiencia de elaboracion de un primer

  11. A Study of Failure Criteria of Fibrous Composite Materials

    Science.gov (United States)

    Paris, Federico; Jackson, Karen E. (Technical Monitor)

    2001-01-01

    The research described in this paper is focused on two areas: (1) evaluation of existing composite failure criteria in the nonlinear, explicit transient dynamic finite element code, MSC.Dytran, and (2) exploration of the possibilities for modification of material and failure models to account for large deformations, progressive failure, and interaction of damage accumulation with stress/strain response of laminated composites. Following a review of the MSC.Dytran user manual, a bibliographical review of existing failure criteria of composites was performed. The papers considered most interesting for the objective of this report are discussed in section 2. The failure criteria included in the code under consideration are discussed in section 3. A critical summary of the present procedures to perform analysis and design of composites is presented in section 4. A study of the most important historical failure criteria for fibrous composite materials and some of the more recent modifications proposed were studied. The result of this analysis highlighted inadequacies in the existing failure criteria and the need to perform some numerical analyses to elucidate the answer to questions on which some of the proposed criteria are based. A summary of these ideas, which is a proposal of studies to be developed, is presented in section 5. Finally, some ideas for future developments are summarized in section 6.

  12. Root-cause analysis and health failure mode and effect analysis: two leading techniques in health care quality assessment.

    Science.gov (United States)

    Shaqdan, Khalid; Aran, Shima; Daftari Besheli, Laleh; Abujudeh, Hani

    2014-06-01

    In this review article, the authors provide a detailed series of guidelines for effectively performing root-cause analysis (RCA) and health failure mode and effect analysis (HFMEA). RCA is a retrospective approach used to ascertain the "root cause" of a problem that has already occurred, whereas HFMEA is a prospective risk assessment tool whose aim is to recognize risks to patient safety. RCA and HFMEA are used for the prevention of errors or recurring errors to create a safer workplace, maintain high standards in health care quality, and incorporate time-saving and cost-saving modifications to favorably affect the patient care environment. The principles and techniques provided here should allow reviewers to better understand the features of RCA and HFMEA and how to apply these processes appropriately. These principles include how to organize a team, identify root causes, seed out proximate causes, graphically describe the process, conduct a hazard analysis, and develop and implement potential action plans.

  13. Summary receiver operating characteristics (SROC) and hierarchical SROC models for analysis of diagnostic test evaluations of antibody ELISAs for paratuberculosis.

    Science.gov (United States)

    Toft, Nils; Nielsen, Søren S

    2009-11-15

    Critical, systematic reviews of available diagnostic test evaluations are a meticulous approach to synthesize evidence about a diagnostic test. However, often the review finds that data quality is poor due to deficiencies in design and reporting of the test evaluations and formal statistical comparisons are discouraged. Even when only simple summary measures are appropriate, the strong correlation between sensitivity and specificity and their dependence on differences in diagnostic threshold across studies, creates the need for tools to summarise properties of the diagnostic test under investigation. This study presents summary receiver operating characteristics (SROC) analysis as a means to synthesize information from diagnostic test evaluation studies. Using data from a review of diagnostic tests for ante mortem diagnosis of paratuberculosis as an illustration, SROC and hierarchical SROC (HSROC) analysis were used to estimate overall diagnostic accuracies of antibody ELISAs for bovine paratuberculosis while accounting for covariates: the target condition (infectious or infected) used in the test evaluation (one for the evaluation of Se and one for Sp); and the type of test (serum vs. milk). The methods gave comparable results (regarding the estimated diagnostic log odds ratio), considering the small sample size and the quality of data. The SROC analysis found a difference in the performance of tests when the target condition for evaluation of Se was infected rather than infectious, suggesting that ELISAs are not suitable for detecting infected cattle. However, the SROC model does not take differences in sample size between study units into account, whereas the HSROC allows for both between and within study variation. Considering the small sample size, more credibility should be given to the results of the HSROC. For both methods the area under the (H)SROC curve was calculated and results were comparable. The conclusion is that while the SROC is simpler and easier

  14. Analysis of a Large Rock Slope Failure on the East Wall of the LAB Chrysotile Mine in Canada: Back Analysis, Impact of Water Infilling and Mining Activity

    Science.gov (United States)

    Grenon, Martin; Caudal, Philippe; Amoushahi, Sina; Turmel, Dominique; Locat, Jacques

    2017-02-01

    A major mining slope failure occurred in July 2012 on the East wall of the LAB Chrysotile mine in Canada. The major consequence of this failure was the loss of the local highway (Road 112), the main commercial link between the region and the Northeast USA. LiDAR scanning and subsequent analyses were performed and enabled quantifying the geometry and kinematics of the failure area. Using this information, this paper presents the back analysis of the July 2012 failure. The analyses are performed using deterministic and probabilistic limit equilibrium analysis and finite-element shear strength reduction analysis modelling. The impact of pit water infilling on the slope stability is investigated. The impact of the mining activity in 2011 in the lower part of the slope is also investigated through a parametric analysis.

  15. Reliability Analysis of Phased Mission Systems by the Considering the Sensitivity Analysis, Uncertainty and Common Cause Failure Analysis using the GO-FLOW Methodology

    Directory of Open Access Journals (Sweden)

    Muhammad Hashim

    2013-04-01

    Full Text Available The reliability is the probability that a device will perform its required function under stated conditions for a specified period of time. The Common Cause Failure (CCFs is the multiple failures and has long been recognized (U.S. NRC, 1975 as an important issue in the Probabilistic Safety Assessment (PSA and uncertainty and sensitivity analysis has the important information for the evaluation of system reliability. In this study, two cases has been considered, in the first case, author have made the analysis of reliability of PWR safety system by GO-FLOW methodology alternatively to Fault Tree Analysis and Even Tree because it is success-oriented system analysis technique and comparatively easy to conduct the reliability analysis of the complex system. In the second case, sensitivity analysis has been made in order to prioritize the important parameters which have largest contribution to system reliability and also for common cause failure analysis and uncertainty analysis. For an example of phased mission system, PWR containment spray system has been considered.

  16. A Mid-Layer Model for Human Reliability Analysis: Understanding the Cognitive Causes of Human Failure Events

    Energy Technology Data Exchange (ETDEWEB)

    Stacey M. L. Hendrickson; April M. Whaley; Ronald L. Boring; James Y. H. Chang; Song-Hua Shen; Ali Mosleh; Johanna H. Oxstrand; John A. Forester; Dana L. Kelly; Erasmia L. Lois

    2010-06-01

    The Office of Nuclear Regulatory Research (RES) is sponsoring work in response to a Staff Requirements Memorandum (SRM) directing an effort to establish a single human reliability analysis (HRA) method for the agency or guidance for the use of multiple methods. As part of this effort an attempt to develop a comprehensive HRA qualitative approach is being pursued. This paper presents a draft of the method’s middle layer, a part of the qualitative analysis phase that links failure mechanisms to performance shaping factors. Starting with a Crew Response Tree (CRT) that has identified human failure events, analysts identify potential failure mechanisms using the mid-layer model. The mid-layer model presented in this paper traces the identification of the failure mechanisms using the Information-Diagnosis/Decision-Action (IDA) model and cognitive models from the psychological literature. Each failure mechanism is grouped according to a phase of IDA. Under each phase of IDA, the cognitive models help identify the relevant performance shaping factors for the failure mechanism. The use of IDA and cognitive models can be traced through fault trees, which provide a detailed complement to the CRT.

  17. Analysis of middle bearing failure in rotor jet engine using tip-timing and tip-clearance techniques

    Science.gov (United States)

    Rzadkowski, R.; Rokicki, E.; Piechowski, L.; Szczepanik, R.

    2016-08-01

    The reported problem is the failure of the middle bearing in an aircraft rotor engine. Tip-timing and tip-clearance and variance analyses are carried out on a compressor rotor blade in the seventh stage above the middle bearing. The experimental analyses concern both an aircraft engine with a middle bearing in good working order and an engine with a damaged middle bearing. A numerical analysis of seventh stage blade free vibration is conducted to explain the experimental results. This appears to be an effective method of predicting middle bearing failure. The results show that variance first increases in the initial stages of bearing failure, but then starts to decrease and stabilize, and then again decrease shortly before complete bearing failure.

  18. Optimisation of shock absorber process parameters using failure mode and effect analysis and genetic algorithm

    Science.gov (United States)

    Mariajayaprakash, Arokiasamy; Senthilvelan, Thiyagarajan; Vivekananthan, Krishnapillai Ponnambal

    2013-07-01

    The various process parameters affecting the quality characteristics of the shock absorber during the process were identified using the Ishikawa diagram and by failure mode and effect analysis. The identified process parameters are welding process parameters (squeeze, heat control, wheel speed, and air pressure), damper sealing process parameters (load, hydraulic pressure, air pressure, and fixture height), washing process parameters (total alkalinity, temperature, pH value of rinsing water, and timing), and painting process parameters (flowability, coating thickness, pointage, and temperature). In this paper, the process parameters, namely, painting and washing process parameters, are optimized by Taguchi method. Though the defects are reasonably minimized by Taguchi method, in order to achieve zero defects during the processes, genetic algorithm technique is applied on the optimized parameters obtained by Taguchi method.

  19. Molecular analysis of genes on Xp controlling Turner syndrome and premature ovarian failure (POF).

    Science.gov (United States)

    Zinn, A R; Ross, J L

    2001-06-01

    Monosomy X has been known to be the chromosomal basis of Turner syndrome (TS) for more than four decades. A large body of cytogenetic data indicates that most TS features are due to reduced dosage of genes on the short arm of the X chromosome (Xp). Phenotype mapping studies using molecular cytogenetic and genetic techniques are beginning to localize the Xp genes that are important for various TS features, and a comprehensive catalog of candidate genes is becoming available through the Human Genome Project and related research. It is now possible to assess the contributions of individual genes to the TS phenotype by mutational analysis of karyotypically normal persons with specific TS features. This strategy has succeeded in identifying a gene involved in short stature and is being applied to premature ovarian failure and other TS phenotypes.

  20. Human factors process failure modes and effects analysis (HF PFMEA) software tool

    Science.gov (United States)

    Chandler, Faith T. (Inventor); Valentino, William D. (Inventor); Philippart, Monica F. (Inventor); Relvini, Kristine M. (Inventor); Bessette, Colette I. (Inventor); Shedd, Nathaneal P. (Inventor)

    2011-01-01

    Methods, computer-readable media, and systems for automatically performing Human Factors Process Failure Modes and Effects Analysis for a process are provided. At least one task involved in a process is identified, where the task includes at least one human activity. The human activity is described using at least one verb. A human error potentially resulting from the human activity is automatically identified, the human error is related to the verb used in describing the task. A likelihood of occurrence, detection, and correction of the human error is identified. The severity of the effect of the human error is identified. The likelihood of occurrence, and the severity of the risk of potential harm is identified. The risk of potential harm is compared with a risk threshold to identify the appropriateness of corrective measures.

  1. Damage and Failure Analysis of AZ31 Alloy Sheet in Warm Stamping Processes

    Science.gov (United States)

    Zhao, P. J.; Chen, Z. H.; Dong, C. F.

    2016-07-01

    In this study, a combined experimental-numerical investigation on the failure of AZ31 Mg alloy sheet in the warm stamping process was carried out based on modified GTN damage model which integrated Yld2000 anisotropic yield criterion. The constitutive equations of material were implemented into a VUMAT subroutine for solver ABAQUS/Explicit and applied to the formability analysis of mobile phone shell. The morphology near the crack area was observed using SEM, and the anisotropic damage evolution at various temperatures was simulated. The distributions of plastic strain, damage evolution, thickness, and fracture initiation obtained from FE simulation were analyzed. The corresponding forming limit diagrams were worked out, and the comparison with the experimental data showed a good agreement.

  2. A blackboard model of an expert system for failure mode and effects analysis

    Science.gov (United States)

    Russomanno, David J.; Bonnell, Ronald D.; Bowles, John B.

    The design of an expert system to assist in performing a failure mode and effects analysis (FMEA) is approached from a knowledge-use-level perspective to provide a thorough understanding of the problem and insight into the knowledge and expertise needed to automate the FMEA process. A blackboard model is a conceptual model that provides the organizational principles required for the design of an expert system without actually specifying its realization. In the blackboard model of an intelligent FMEA, the system is functionally decomposed into a set of knowledge sources, each containing the knowledge associated with a subfunction of the FMEA process. The conceptual model derived can be used to evaluate attempts to automate the FMEA process, and it can serve as the foundation for further research into automating the FMEA process. An example is presented illustrating the interaction among the knowledge sources in the blackboard model to construct a FMEA for a domestic hot water heater.

  3. An approach to support entries for a design failure modes and effects analysis

    Directory of Open Access Journals (Sweden)

    Banciu Felicia Veronica

    2017-01-01

    Full Text Available The design of a fixture device is very laborious, requiring consideration of many issues from series production, information on the raw part material, required precision surfaces, ensuring an appropriate orientation scheme, continue with requirements related device itself as number of parts, parts type, complexity, manageability, easy operation and maintenance. That is why realising a proper analyse regarding the possible failures associated to these issues is overwhelming. This paper’s aim is to propose an approach for collection of items necessary for starting a Design FMEA, using Functional Analysis, TRIZ functional modelling and axiomatic design approaches. The proposed approach – to extract items for a FMEA analyse – is applied to an example of an expanding mandrel regarding its internal components and theirs relations in order to accomplish the main requirement: the accurate locating and clamping of a part.

  4. Association Analysis of System Failure in Wide Area Backup Protection System

    Science.gov (United States)

    Zhang, Yagang; Sun, Yi

    2015-12-01

    Wide area backup protection algorithm based on fault component identification is the heart of the whole wide area backup protection system, its validity and reliability is a problem which needs to be first considered in the engineering practice applications of wide area backup protection system. Wide are backup protection algorithm mainly use two kinds of wide area information to realize protection criterion, one is electrical quantity information, such as voltage, current, etc. Another one is protection action and circuit breaker information. The wide area backup protection algorithm based on electrical quantity information is mainly utilizing the significant change of electrical quantity to search fault component, and the primary means include current differential method of wide area multi-measuring points, the comparison method of calculation and measurement, the multiple statistics method. In this paper, a novel and effective association analysis of system failure in wide area backup protection system will be discussed carefully, and the analytical results are successful and reliable.

  5. A Review of Failure Analysis Methods for Advanced 3D Microelectronic Packages

    Science.gov (United States)

    Li, Yan; Srinath, Purushotham Kaushik Muthur; Goyal, Deepak

    2016-01-01

    Advanced three dimensional (3D) packaging is a key enabler in driving form factor reduction, performance benefits, and package cost reduction, especially in the fast paced mobility and ultraportable consumer electronics segments. The high level of functional integration and the complex package architecture pose a significant challenge for conventional fault isolation (FI) and failure analysis (FA) methods. Innovative FI/FA tools and techniques are required to tackle the technical and throughput challenges. In this paper, the applications of FI and FA techniques such as Electro Optic Terahertz Pulse Reflectometry, 3D x-ray computed tomography, lock-in thermography, and novel physical sample preparation methods to 3D packages with package on package and stacked die with through silicon via configurations are reviewed, along with the key FI and FA challenges.

  6. Statistical Analysis of the Progressive Failure Behavior for Fiber-Reinforced Polymer Composites under Tensile Loading

    Directory of Open Access Journals (Sweden)

    Fang Wang

    2014-01-01

    Full Text Available An analytical approach with the help of numerical simulations based on the equivalent constraint model (ECM was proposed to investigate the progressive failure behavior of symmetric fiber-reinforced composite laminates damaged by transverse ply cracking. A fracture criterion was developed to describe the initiation and propagation of the transverse ply cracking. This work was also concerned with a statistical distributions of the critical fracture toughness values with due consideration given to the scale size effect. The Monte Carlo simulation technique coupled with statistical analysis was applied to study the progressive cracking behaviors of composite structures, by considering the effects of lamina properties and lay-up configurations. The results deduced from the numerical procedure were in good agreement with the experimental results obtained for laminated composites formed by unidirectional fiber reinforced laminae with different orientations.

  7. Noninvasive ventilation and exercise tolerance in heart failure: A systematic review and meta-analysis

    Directory of Open Access Journals (Sweden)

    Daiana C. Bündchen

    2014-10-01

    Full Text Available Background: Patients with heart failure (HF usually develop exercise intolerance. In this context, noninvasive ventilation (NIV can help to increase physical performance. Objective: To undertake a systematic review and meta-analysis of randomized controlled trials that evaluated the effects of NIV on exercise tolerance in patients with HF. Method: Search Strategy: Articles were searched in the following databases: Physiotherapy Evidence Database (PEDro, Scientific Electronic Library Online (SciELO, and MEDLINE. Selection Criteria: This review included only randomized controlled trials involving patients with HF undergoing NIV, with or without other therapies, that used exercise tolerance as an outcome, verified by the distance travelled in the six-minute walk test (6MWT, VO2peak in the cardiopulmonary test, time spent in testing, and dyspnea. Data Collection and Analysis: The methodological quality of the studies was rated according to the PEDro scale. Data were pooled in fixed-effect meta-analysis whenever possible. Results: Four studies were selected. A meta-analysis including 18 participants showed that the use of NIV prior to the 6MWT promoted increased distance, [mean difference 65.29 m (95% CI 38.80 to 91.78]. Conclusions: The use of NIV prior to the 6MWT in patients with HF may promote increased distance. However, the limited number of studies may have compromised a more definitive conclusion on the subject.

  8. Logistic regression analysis of the risk factors of acute renal failure complicating limb war injuries

    Directory of Open Access Journals (Sweden)

    Chang-zhi CHENG

    2011-06-01

    Full Text Available Objective To explore the risk factors of complication of acute renal failure(ARF in war injuries of limbs.Methods The clinical data of 352 patients with limb injuries admitted to 303 Hospital of PLA from 1968 to 2002 were retrospectively analyzed.The patients were divided into ARF group(n=9 and non-ARF group(n=343 according to the occurrence of ARF,and the case-control study was carried out.Ten factors which might lead to death were analyzed by logistic regression to screen the risk factors for ARF,including causes of trauma,shock after injury,time of admission to hospital after injury,injured sites,combined trauma,number of surgical procedures,presence of foreign matters,features of fractures,amputation,and tourniquet time.Results Fifteen of the 352 patients died(4.3%,among them 7 patients(46.7% died of ARF,3(20.0% of pulmonary embolism,3(20.0% of gas gangrene,and 2(13.3% of multiple organ failure.Univariate analysis revealed that the shock,time before admitted to hospital,amputation and tourniquet time were the risk factors for ARF in the wounded with limb injuries,while the logistic regression analysis showed only amputation was the risk factor for ARF(P < 0.05.Conclusion ARF is the primary cause-of-death in the wounded with limb injury.Prompt and accurate treatment and optimal time for amputation may be beneficial to decreasing the incidence and mortality of ARF in the wounded with severe limb injury and ischemic necrosis.

  9. INTEGRATION OF POKA YOKE INTO PROCESS FAILURE MODE AND EFFECT ANALYSIS: A CASE STUDY

    Directory of Open Access Journals (Sweden)

    A. P. Puvanasvaran

    2014-01-01

    Full Text Available The Failure Mode and Effect Analysis (FMEA is a one of the requirements which was required by the Automotive Industries Action Group (AIAG to all the automotive suppliers and manufacturers worldwide through the TS16949 Quality System. There were a lot of dicrepencies detected on implementing the FMEA which directly related to the user experinces and knowledge. The descrepencies cause the FMEA not meeting the objectives of it. Conceptually, Poka Yoke is able to fit into the Process FMEA. Failure Mode and Effect Analysis (FMEA helps predict and prevent problems through proper control or detection methods. Mistake proofing emphasizes detection and correction of mistakes before they become defects. Poka Yoke helps people and processes work correctly the first time. It refers to techniques that make mistakes impossible to commit. These techniques eliminate defects from products and processes as well as substantially improve their quality and reliability. Poka Yoke can be considered an extension of FMEA. The use of simple Poka Yoke ideas and methods in product and process design eliminates both human and mechanical errors. Ultimately, both FMEA and Poka Yoke methodologies result in zero defects and benefit either the end or the next-in-line customer. The first concept of Poka Yoke emphasizes elimination of the cause or occurrence of the error that creates the defects by concentrating on the cause of the error in the process. The defect is prevented by stopping the line or the machine when the root cause of the defect is triggered or detected. The second concept of Poka Yoke focuses on the effectiveness of the detection system. The foolproof detection system eliminates the defect or detects the error that causes defects. The implementation of the Poka Yoke concept in a foolproof detection system eliminates the possibility that error or defects will slip through the process and reach the customer.

  10. A Case Study on Improving Intensive Care Unit (ICU) Services Reliability: By Using Process Failure Mode and Effects Analysis (PFMEA)

    Science.gov (United States)

    Yousefinezhadi, Taraneh; Jannesar Nobari, Farnaz Attar; Goodari, Faranak Behzadi; Arab, Mohammad

    2016-01-01

    Introduction: In any complex human system, human error is inevitable and shows that can’t be eliminated by blaming wrong doers. So with the aim of improving Intensive Care Units (ICU) reliability in hospitals, this research tries to identify and analyze ICU’s process failure modes at the point of systematic approach to errors. Methods: In this descriptive research, data was gathered qualitatively by observations, document reviews, and Focus Group Discussions (FGDs) with the process owners in two selected ICUs in Tehran in 2014. But, data analysis was quantitative, based on failures’ Risk Priority Number (RPN) at the base of Failure Modes and Effects Analysis (FMEA) method used. Besides, some causes of failures were analyzed by qualitative Eindhoven Classification Model (ECM). Results: Through FMEA methodology, 378 potential failure modes from 180 ICU activities in hospital A and 184 potential failures from 99 ICU activities in hospital B were identified and evaluated. Then with 90% reliability (RPN≥100), totally 18 failures in hospital A and 42 ones in hospital B were identified as non-acceptable risks and then their causes were analyzed by ECM. Conclusions: Applying of modified PFMEA for improving two selected ICUs’ processes reliability in two different kinds of hospitals shows that this method empowers staff to identify, evaluate, prioritize and analyze all potential failure modes and also make them eager to identify their causes, recommend corrective actions and even participate in improving process without feeling blamed by top management. Moreover, by combining FMEA and ECM, team members can easily identify failure causes at the point of health care perspectives. PMID:27157162

  11. 塑封IC失效分析及对策%Failure Analysis and Countermeasures for Plastic IC

    Institute of Scientific and Technical Information of China (English)

    王立国; 邵刚

    2012-01-01

    阐述了塑封IC(集成电路)常见的失效现象,对塑封IC失效的几种分析方法和分析技术做了叙述,然后提出塑封IC失效分析的步骤,并从设计、工艺和材料控制、包装、运输等方面提出改善塑封IC可靠性的措施。%Described the failure of plastic IC common phenomenon in detail several of Plastic IC failure analysis methods and analysis techniques do narrative,and then put forward the steps Plastic IC failure analysis and design,process and material control,transportation and other aspects of the box measures to improve the reliability of plastic IC.

  12. The L(1/2) regularization approach for survival analysis in the accelerated failure time model.

    Science.gov (United States)

    Chai, Hua; Liang, Yong; Liu, Xiao-Ying

    2015-09-01

    The analysis of high-dimensional and low-sample size microarray data for survival analysis of cancer patients is an important problem. It is a huge challenge to select the significantly relevant bio-marks from microarray gene expression datasets, in which the number of genes is far more than the size of samples. In this article, we develop a robust prediction approach for survival time of patient by a L(1/2) regularization estimator with the accelerated failure time (AFT) model. The L(1/2) regularization could be seen as a typical delegate of L(q)(0regularization methods and it has shown many attractive features. In order to optimize the problem of the relevant gene selection in high-dimensional biological data, we implemented the L(1/2) regularized AFT model by the coordinate descent algorithm with a renewed half thresholding operator. The results of the simulation experiment showed that we could obtain more accurate and sparse predictor for survival analysis by the L(1/2) regularized AFT model compared with other L1 type regularization methods. The proposed procedures are applied to five real DNA microarray datasets to efficiently predict the survival time of patient based on a set of clinical prognostic factors and gene signatures.

  13. [Pharmacological Basis for Therapeutics. Pharmacological Analysis of Summary of Product Characteristics (SPC) for Physicians].

    Science.gov (United States)

    Lechat, Philippe

    2015-01-01

    The summary of product characteristics, the SPC, is the major annex document of Marketing Authorisation (MA) dossier for a medicine. This document is the reference document for health care professionnals since it contains all necessary and opposable information for its therapeutic use. The SPC is initially submitted by the MA applicant and deeply revised in details by regulatory authorities, the national agencies for national MA, and the European Medicine Agency (EMA) for the european centralized procedures. The SPC presents with 12 sections each one being divided into several paragraphs. Sections 1-3 present the name, dosage, qualitative and quantitative composition, the pharmaceutical form of the medicine. Section 4 contains all the clinical particulars: Therapeutic indications, posology and methods of administration, contra-indications, special warnings and precautions for use, interactions, impact on fertility, contraception, pregnancy, lactation, effects on ability to drive and use machines, undesirable effects and risk associated with overdose. Section 5 describes pharmacological properties (pharmacodynamics and pharmacokinetics) and preclinical safety data. Section 6 describes the pharmaceutical particulars: excipients, incompatibilities, shelf live, nature and content of container, special precautions for disposal. Sections 7-10 are administrative ones (date of MA, MA holder), sections 11 and 12 are specific to radiopharmaceuticals (dosimetry and modalities of preparation). SPC is available free of charge on national regulatory agency websites and on EMA website. Sections of SPC finally have to be considered as the pharmacological basis of therapeutic use for each medicine. © 2015 Société Française de Pharmacologie et de Thérapeutique.

  14. Research Summaries

    Science.gov (United States)

    Brock, Stephen E., Ed.

    2012-01-01

    In this column, members of the NASP Crisis Management in the Schools Interest Group provide summaries of three studies relevant to school crisis response. The first study investigated the prevalence of posttraumatic stress disorder (PTSD) among rescue workers. The second article explored the Child and Family Traumatic Stress Intervention, which is…

  15. Mergeable summaries

    DEFF Research Database (Denmark)

    Agarwal, Pankaj K.; Graham, Graham; Huang, Zengfeng;

    2013-01-01

    of the datasets. But some other fundamental ones, like those for heavy hitters and quantiles, are not (known to be) mergeable. In this article, we demonstrate that these summaries are indeed mergeable or can be made mergeable after appropriate modifications. Specifically, we show that for ϵ-approximate heavy...

  16. Executive summary

    NARCIS (Netherlands)

    van Nimwegen, N.; van Nimwegen, N.; van der Erf, R.

    2009-01-01

    The Demography Monitor 2008 gives a concise overview of current demographic trends and related developments in education, the labour market and retirement for the European Union and some other countries. This executive summary highlights the major findings of the Demography Monitor 2008 and further

  17. The history of NATO TNF policy: The role of studies, analysis and exercises conference proceedings. Volume 1, Introduction and summary

    Energy Technology Data Exchange (ETDEWEB)

    Rinne, R.L. [ed.

    1994-02-01

    This conference was organized to study and analyze the role of simulation, analysis, modeling, and exercises in the history of NATO policy. The premise was not that the results of past studies will apply to future policy, but rather that understanding what influenced the decision process -- and how -- would be of value. The structure of the conference was built around discussion panels. The panels were augmented by a series of papers and presentations focusing on particular TNF events, issues, studies or exercise. The conference proceedings consist of three volumes. This volume, Volume 1, contains the conference introduction, agenda, biographical sketches of principal participants, and analytical summary of the presentations and discussion panels. Volume 2 contains a short introduction and the papers and presentations from the conference. Volume 3 contains selected papers by Brig. Gen. Robert C. Richardson III (Ret.).

  18. Integrating decision-making trial and evaluation laboratory model and failure mode and effect analysis to determine the priority in solving production problems

    Directory of Open Access Journals (Sweden)

    Yu-Cheng Lee

    2016-04-01

    Full Text Available Failure mode and effect analysis has been applied in manufacturing and service industries but can still be improved. Failure mode and effect analysis is a common tool used to evaluate risk priority number; however, numerous scholars have doubted the effectiveness of failure mode and effect analysis and have thus proposed methods for correcting failure mode and effect analysis from its conventional formula. Because implemented actions can determine or influence resource allocation and its effects, completing one corrective action can occasionally simultaneously improve various failure modes. In this study, failure mode and effect analysis and decision-making trial and evaluation laboratory were integrated to correct failure modes and increase their effectiveness. First, failure mode and effect analysis was employed to identify the items for improvement. Second, decision-making trial and evaluation laboratory was adopted to examine the reciprocal influences and causality among these items. Finally, the priority for improving the items was proposed. By combining the advantages of failure mode and effect analysis and decision-making trial and evaluation laboratory, this research method complemented the shortcomings of the two techniques. According to the empirical research of this case study in which decision-making trial and evaluation laboratory was employed to analyze the causality among the items of the failure modes, the malfunction of production lines can be solved faster and more effectively compared with merely considering the size of risk priority number values.

  19. Failure probability analysis of coal crushing induced by uncertainty of influential parameters under condition of in-situ reservoir

    Institute of Scientific and Technical Information of China (English)

    张立松; 闫相祯; 杨秀娟; 田中兰; 杨恒林

    2014-01-01

    The uncertainties of some key influence factors on coal crushing, such as rock strength, pore pressure and magnitude and orientation of three principal stresses, can lead to the uncertainty of coal crushing and make it very difficult to predict coal crushing under the condition of in-situ reservoir. To account for the uncertainty involved in coal crushing, a deterministic prediction model of coal crushing under the condition of in-situ reservoir was established based on Hoek-Brown criterion. Through this model, key influence factors on coal crushing were selected as random variables and the corresponding probability density functions were determined by combining experiment data and Latin Hypercube method. Then, to analyze the uncertainty of coal crushing, the first- order second-moment method and the presented model were combined to address the failure probability involved in coal crushing analysis. Using the presented method, the failure probabilities of coal crushing were analyzed for WS5-5 well in Ningwu basin, China, and the relations between failure probability and the influence factors were furthermore discussed. The results show that the failure probabilities of WS5-5 CBM well vary from 0.6 to 1.0; moreover, for the coal seam section at depth of 784.3-785 m, the failure probabilities are equal to 1, which fit well with experiment results; the failure probability of coal crushing presents nonlinear growth relationships with the increase of principal stress difference and the decrease of uniaxial compressive strength.

  20. Statistical analysis of the nuclear power plant equipment failure data in non-homogeneous flow of events

    Directory of Open Access Journals (Sweden)

    A.V. Antonov

    2016-12-01

    Full Text Available Operation of technical equipment involves three consecutive stages, each of which is characterized by a particular trend in the behavior of the failure flow parameter (FFP. The FFP value is approximately constant during normal operation. In this case, the equipment operation process is assumed to be temporally homogeneous and the reliability indicators are calculated by conventional methods. At the burn-in stage, the FFP decreases with time while increasing at the aging stage. Therefore, the operating times between two successive failures at the burn-in and aging stages are not similarly distributed random values and the flow of events cannot be assumed to be recurrent. It shall be taken into account in the reliability performance calculation that the flow of failures is temporally inhomogeneous. The paper describes a method to estimate the NPP equipment reliability indicators allowing the potential inhomogeneity of the failure flow to be taken into account. The specific nature of incoming statistical data on failures is shown. The application of the normalizing flow function model for the calculation of required reliability indicators is described. A practical example of an analysis of data on the Bilibino NPP CPS KNK-56 component failures is presented.

  1. Face haulage equipment failure analysis. Volume I. Technical information and conclusions. Final technical report as of November 30, 1980

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, W.N.; Orona, F.

    1980-11-01

    Face haulage equipment used in conjunction with continuous miners (shuttle cars, diesel haulers, battery scoops, and bridge conveyors) was investigated by recording section delay reports for computer analysis to determine the effect of haulage equipment failures and downtime on productivity, pinpoint the causes of machine failures and downtime, and develop the possible design and operational changes required to reduce machine failures and downtime and increase section productivity. For the mobile vehicle type of haulage (shuttle car, diesel hauler, and battery scoop) failure of one unit in multiple unit haulage operations would not normally stop section production. Bridge conveyors as a haulage system provide continuous haulage of section production but when any part of the bridge system fails, the section production is stopped. In the course of this program, it was determined through the use of daily section shift reports on 200 machines that face haulage equipment is responsible for about 40 to 56 minutes of lost section production time per shift. The most prevalent failure for shuttle cars was found to be the trailing cable umbilical. Bridge conveyors had the most trouble with the conveyor subsystem. Discussions of these and other recorded failures are developed with possible solutions outlined for future implementation. This report only covers the face haulage element of the continuous miner system. Companion reports were developed for the continuous miner and roof bolter elements under separate task orders.

  2. Secondary Containment System component failure data analysis from 1984 to 1991

    Energy Technology Data Exchange (ETDEWEB)

    Cadwallader, L.C. [EG and G Idaho, Inc., Idaho Falls, ID (United States); Sanchez, D.P. [Los Alamos National Lab., NM (United States)

    1992-08-01

    This report gives the failure rates for the major tritium containing glovebox systems that comprise the Secondary Containment System at the Tritium systems Test Assembly, which is a fusion research and technology facility at the Los Alamos National Laboratory. The component failure reports, the numbers of components, and operating times or demands are all given in this report, and sample calculations of the binomial demand failure rates and poisson hourly failure rates are given in the appendices. The failure rates for these components form a solid data point based on actual operating experience, where there is very little published information. The eight years of nearly continuous Secondary Containment System operations should result in steady state failure rate values. These data should be useful for future fusion reactor design work and safety assessment tasks.

  3. III SBC Guidelines on the Analysis and Issuance of Electrocardiographic Reports - Executive Summary

    Directory of Open Access Journals (Sweden)

    Carlos Alberto Pastore

    Full Text Available Abstract The third version of the guidelines covers recently described topics, such as ion channel diseases, acute ischemic changes, the electrocardiogram in athletes, and analysis of ventricular repolarization. It sought to revise the criteria for overloads, conduction disorders, and analysis of data for internet transmission.

  4. Summary Report: First Research Coordination Meeting on ReferenceDatabase for Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Richard B.; Trkov, Andrej

    2005-10-31

    Potential problems associated with nuclear data for neutronactivation analysis were identified, the scope of the work to beundertaken was defined together with its priorities, and tasks wereassigned to participants. Data testing and measurements refer to gammaspectrum peak evaluations, detector efficiency calibration, neutronspectrum characteristics and reference materials analysis.

  5. Summary Report: First Research Coordination Meeting on ReferenceDatabase for Neutron Activation Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Firestone, Richard B.; Trkov, Andrej

    2005-10-01

    Potential problems associated with nuclear data for neutronactivation analysis were identified, the scope of the work to beundertaken was defined together with its priorities, and tasks wereassigned to participants. Data testing and measurements refer to gammaspectrumpeak evaluations, detector efficiency calibration, neutronspectrum characteristics and reference materials analysis.

  6. Summary of research in applied mathematics, numerical analysis, and computer sciences

    Science.gov (United States)

    1986-01-01

    The major categories of current ICASE research programs addressed include: numerical methods, with particular emphasis on the development and analysis of basic numerical algorithms; control and parameter identification problems, with emphasis on effective numerical methods; computational problems in engineering and physical sciences, particularly fluid dynamics, acoustics, and structural analysis; and computer systems and software, especially vector and parallel computers.

  7. III SBC Guidelines on the Analysis and Issuance of Electrocardiographic Reports - Executive Summary

    Science.gov (United States)

    Pastore, Carlos Alberto; Samesima, Nelson; Pereira-Filho, Horacio Gomes

    2016-01-01

    The third version of the guidelines covers recently described topics, such as ion channel diseases, acute ischemic changes, the electrocardiogram in athletes, and analysis of ventricular repolarization. It sought to revise the criteria for overloads, conduction disorders, and analysis of data for internet transmission. PMID:27982266

  8. Instructional Changes Adopted for an Engineering Course: Cluster Analysis on Academic Failure

    Science.gov (United States)

    Álvarez-Bermejo, José A.; Belmonte-Ureña, Luis J.; Martos-Martínez, África; Barragán-Martín, Ana B.; Simón-Márquez, María M.

    2016-01-01

    As first year students come from diverse backgrounds, basic skills should be accessible to everyone as soon as possible. Transferring such skills to these students is challenging, especially in highly technical courses. Ensuring that essential knowledge is acquired quickly promotes the student’s self-esteem and may positively influence failure rates. Metaphors can help do this. Metaphors are used to understand the unknown. This paper shows how we made a turn in student learning at the University of Almeria. Our hypothesis assumed that metaphors accelerate the acquisition of basic knowledge so that other skills built on that foundation are easily learned. With these goals in mind, we changed the way we teach by using metaphors and abstract concepts in a computer organization course, a technical course in the first year of an information technology engineering degree. Cluster analysis of the data on collective student performance after this methodological change clearly identified two distinct groups. These two groups perfectly matched the “before and after” scenarios of the use of metaphors. The study was conducted during 11 academic years (2002/2003 to 2012/2013). The 475 observations made during this period illustrate the usefulness of this change in teaching and learning, shifting from a propositional teaching/learning model to a more dynamic model based on metaphors and abstractions. Data covering the whole period showed favorable evolution of student achievement and reduced failure rates, not only in this course, but also in many of the following more advanced courses. The paper is structured in five sections. The first gives an introduction, the second describes the methodology. The third section describes the sample and the study carried out. The fourth section presents the results and, finally, the fifth section discusses the main conclusions. PMID:27895611

  9. Instructional changes adopted for an engineering course: cluster analysis on academic failure.

    Directory of Open Access Journals (Sweden)

    Jose Antonio Alvarez Bermejo

    2016-11-01

    Full Text Available As first-year students come from diverse backgrounds, basic skills should be accessible to everyone as soon as possible. Transferring such skills to these students is challenging, especially in highly technical courses. Ensuring that essential knowledge is acquired quickly promotes the student’s self-esteem and may positively influence failure rates. Metaphors can help do this. Metaphors are used to understand the unknown. This paper shows how we made a turn in student learning at the University of Almeria. Our hypothesis assumed that metaphors accelerate the acquisition of basic knowledge so that other skills built on that foundation are easily learned. With these goals in mind, we changed the way we teach by using metaphors and abstract concepts in a computer organisation course, a technical course in the first year of an information technology engineering degree. Cluster analysis of the data on collective student performance after this methodological change clearly identified two distinct groups. These two groups perfectly matched the before and after scenarios of the use of metaphors. The study was conducted during 11 academic years (2002/2003 to 2012/2013. The 475 observations made during this period illustrate the usefulness of this change in teaching and learning, shifting from a propositional teaching/learning model to a more dynamic model based on metaphors and abstractions. Data covering the whole period showed favourable evolution of student achievement and reduced failure rates, not only in this course, but also in many of the following more advanced courses.The paper is structured in five sections. The first gives an introduction, the second describes the methodology. The third section describes the sample and the study carried out. The fourth section presents the results and, finally, the fifth section discusses the main conclusions.

  10. Failure-mode and effects analysis in improving a drug distribution system.

    Science.gov (United States)

    McNally, K M; Page, M A; Sunderland, V B

    1997-01-15

    The medication error rate in an existing ward stock drug distribution system and in an alternative system developed after failure-mode and effects analysis (FMEA) was applied to the ward stock system was studied. In the ward stock system of a large teaching hospital in Western Australia, bulk drug packs were stored in cupboards on the wards, and drug products were transferred to drug trolleys before dose administration by nurses. A pharmacist used the disguised-observer technique to determine the error rate in the ward stock system for a medical ward and a surgical ward. The errors and each step in the system were studied by FMEA. A unit supply individual-patient dispensing (USIPD) system was formulated to respond to the failure modes identified. In this system, a five-day supply of medication was dispensed for each patient from a satellite pharmacy close to the ward. Medication charts were reviewed by a pharmacist, and drugs were dispensed in labeled vials that were placed in a locked drawer at the patient's bedside. The error rate under the USIPD system was determined. Problem areas in the ward stock system identified by FMEA included drug availability, review of orders, drug selection, patient-related issues, and use of nurses' time. The percentage of opportunities during which any error occurred was significantly lower under the USIPD system on both wards. FMEA was used to identify deficiencies in the ward stock system that led to medication errors in an Australian hospital. An alternative drug distribution system designed to address the problems identified was associated with fewer errors.

  11. A Systematic Review and Meta-Analysis of Circulating Biomarkers Associated with Failure of Arteriovenous Fistulae for Haemodialysis

    Science.gov (United States)

    Morris, Dylan R.; Bhandari, Abhishta P.; Moxon, Joseph V.

    2016-01-01

    Background Arteriovenous fistula (AVF) failure is a significant cause of morbidity and expense in patients on maintenance haemodialysis (HD). Circulating biomarkers could be valuable in detecting patients at risk of AVF failure and may identify targets to improve AVF outcome. Currently there is little consensus on the relationship between circulating biomarkers and AVF failure. The aim of this systematic review was to identify circulating biomarkers associated with AVF failure. Methods Studies evaluating the association between circulating biomarkers and the presence or risk of AVF failure were systematically identified from the MEDLINE, EMBASE and Cochrane Library databases. No restrictions on the type of study were imposed. Concentrations of circulating biomarkers of routine HD patients with and without AVF failure were recorded and meta-analyses were performed on biomarkers that were assessed in three or more studies with a composite population of at least 100 participants. Biomarker concentrations were synthesized into inverse-variance random-effects models to calculate standardized mean differences (SMD) and 95% confidence intervals (CI). Results Thirteen studies comprising a combined population of 1512 participants were included after screening 2835 unique abstracts. These studies collectively investigated 48 biomarkers, predominantly circulating molecules which were assessed as part of routine clinical care. Meta-analysis was performed on twelve eligible biomarkers. No significant association between any of the assessed biomarkers and AVF failure was observed. Conclusion This paper is the first systematic review of biomarkers associated with AVF failure. Our results suggest that blood markers currently assessed do not identify an at-risk AVF. Further, rigorously designed studies assessing biological plausible biomarkers are needed to clarify whether assessment of circulating markers can be of any clinical value. PROSPERO registration number CRD42016033845

  12. A Systematic Review and Meta-Analysis of Circulating Biomarkers Associated with Failure of Arteriovenous Fistulae for Haemodialysis.

    Directory of Open Access Journals (Sweden)

    Susan K Morton

    Full Text Available Arteriovenous fistula (AVF failure is a significant cause of morbidity and expense in patients on maintenance haemodialysis (HD. Circulating biomarkers could be valuable in detecting patients at risk of AVF failure and may identify targets to improve AVF outcome. Currently there is little consensus on the relationship between circulating biomarkers and AVF failure. The aim of this systematic review was to identify circulating biomarkers associated with AVF failure.Studies evaluating the association between circulating biomarkers and the presence or risk of AVF failure were systematically identified from the MEDLINE, EMBASE and Cochrane Library databases. No restrictions on the type of study were imposed. Concentrations of circulating biomarkers of routine HD patients with and without AVF failure were recorded and meta-analyses were performed on biomarkers that were assessed in three or more studies with a composite population of at least 100 participants. Biomarker concentrations were synthesized into inverse-variance random-effects models to calculate standardized mean differences (SMD and 95% confidence intervals (CI.Thirteen studies comprising a combined population of 1512 participants were included after screening 2835 unique abstracts. These studies collectively investigated 48 biomarkers, predominantly circulating molecules which were assessed as part of routine clinical care. Meta-analysis was performed on twelve eligible biomarkers. No significant association between any of the assessed biomarkers and AVF failure was observed.This paper is the first systematic review of biomarkers associated with AVF failure. Our results suggest that blood markers currently assessed do not identify an at-risk AVF. Further, rigorously designed studies assessing biological plausible biomarkers are needed to clarify whether assessment of circulating markers can be of any clinical value. PROSPERO registration number CRD42016033845.

  13. Failure analysis of micro-heating elements suspended on thin membranes

    OpenAIRE

    Briand, Danick; Beaudoin, F.; Courbat, Jérôme; de Rooij, Nicolaas F.; Desplats, R.; Perdu, P.

    2010-01-01

    We report on the degradation of platinum micro-heating elements operating at high temperatures. Devices with platinum heaters suspended on micro-machined dielectric membranes were self-heated at high temperature until failure. Optical and SEM observations combined with mechanical deformation measurements and Thermal Laser Stimulation techniques were used to analyze the failure mechanisms of the micro-heating elements. Platinum atoms migration and breaking of the membrane were two failure mode...

  14. Bayesian Analysis of Zero-failure Data Based on IFRA Distribution

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhi-hua; LIU Hai-tao

    2009-01-01

    For many products, distributions of their life mostly comply with increasing failure rates in average (IFRA). Aiming to these distributions, using properties of IFRA classification, this paper gives a non-parametric method for processing zero-failure data. Estimations of reliabilities in any time are first obtained, and based on a regression model of failure rates, estimations of reliability indexes are given. Finally, a practical example is processed with this method.

  15. Steam generator tube failures

    Energy Technology Data Exchange (ETDEWEB)

    MacDonald, P.E.; Shah, V.N.; Ward, L.W.; Ellison, P.G.

    1996-04-01

    A review and summary of the available information on steam generator tubing failures and the impact of these failures on plant safety is presented. The following topics are covered: pressurized water reactor (PWR), Canadian deuterium uranium (CANDU) reactor, and Russian water moderated, water cooled energy reactor (VVER) steam generator degradation, PWR steam generator tube ruptures, the thermal-hydraulic response of a PWR plant with a faulted steam generator, the risk significance of steam generator tube rupture accidents, tubing inspection requirements and fitness-for-service criteria in various countries, and defect detection reliability and sizing accuracy. A significant number of steam generator tubes are defective and are removed from service or repaired each year. This wide spread damage has been caused by many diverse degradation mechanisms, some of which are difficult to detect and predict. In addition, spontaneous tube ruptures have occurred at the rate of about one every 2 years over the last 20 years, and incipient tube ruptures (tube failures usually identified with leak detection monitors just before rupture) have been occurring at the rate of about one per year. These ruptures have caused complex plant transients which have not always been easy for the reactor operators to control. Our analysis shows that if more than 15 tubes rupture during a main steam line break, the system response could lead to core melting. Although spontaneous and induced steam generator tube ruptures are small contributors to the total core damage frequency calculated in probabilistic risk assessments, they are risk significant because the radionuclides are likely to bypass the reactor containment building. The frequency of steam generator tube ruptures can be significantly reduced through appropriate and timely inspections and repairs or removal from service.

  16. Failure Mode and Effect Analysis (FMEA for confectionery manufacturing in developing countries: Turkish delight production as a case study

    Directory of Open Access Journals (Sweden)

    Sibel Ozilgen

    2012-09-01

    Full Text Available The Failure Mode and Effect Analysis (FMEA was applied for risk assessment of confectionary manufacturing, in whichthe traditional methods and equipment were intensively used in the production. Potential failure modes and effects as well as their possible causes were identified in the process flow. Processing stages that involve intensive handling of food by workers had the highest risk priority numbers (RPN = 216 and 189, followed by chemical contamination risks in different stages of the process. The application of corrective actions substantially reduced the RPN (risk priority number values. Therefore, the implementation of FMEA (The Failure Mode and Effect Analysis model in confectionary manufacturing improved the safety and quality of the final products.

  17. Using a failure modes, effects and diagnostic analysis (FMEDA) to measure diagnostic coverage in programmable electronic systems

    Energy Technology Data Exchange (ETDEWEB)

    Goble, W.M.; Brombacher, A.C

    1999-11-01

    One of the key issues in the quantitative evaluation of programmable electronic systems is the diagnostic capability of the equipment. This is measured by a parameter called the Coverage Factor, C. This factor can vary widely. The range of possible values is often the subject of great debate. Within limits, the diagnostic coverage factor can be calculated by knowing which component failure modes are detected by diagnostics. An extension of the Failure Modes and Effects Analysis (FMEA) can be used to show this information. This extension, called a Failure Modes, Effects and Diagnostic Analysis can serve as a useful design verification tool as well as a means to provide more precise input to reliability and safety modeling.

  18. Noninvasive Ventilation Practice Patterns for Acute Respiratory Failure in Canadian Tertiary Care Centres: A Descriptive Analysis

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    Geneviève C Digby

    2015-01-01

    Full Text Available BACKGROUND: The extent of noninvasive ventilation (NIV use for patients with acute respiratory failure in Canadian hospitals, indications for use and associated outcomes are unknown.

  19. Development of methodology for horizontal-axis wind-turbine dynamic analysis. Summary report

    Energy Technology Data Exchange (ETDEWEB)

    Dugundji, J.

    1982-09-01

    The 3-year effort reported included: (1) review of the MOSTAS computer programs for dynamic analysis of horizontal-axis wind turbines; (2) review of various analysis methods for rotating systems with periodic coefficients; (3) review of structural dynamics analysis tools for large wind turbine; (4) experiments for yaw characteristics of a rotating rotar; (5) development of a finite element model for rotors; (6) development of simple models for aeroelastic; and (7) development of simple models for stability and response of wind turbines on flexible towers.

  20. Assessment of the Reliability ofFractionator Column of the Kaduna Refinery using Failure Modes Effects and Criticality Analysis (FMECA

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    Ibrahim A

    2016-06-01

    Full Text Available —The reliability of a process equipment is the probability that an item will perform a required function under stated condition(s. It is an important issue in any process industry. Failure to assess the reliability of most process equipment had led to huge financial losses. As a result, this research aims at assessing the reliability of the Fractionator column of the Kaduna Refining and Petrochemicals (KRPC, Fluid Catalytic Cracking Unit (FCCU, using the Failure mode, effects and criticality analysis (FMECA. The failure mode effects analysis (FMEA was firstused to identify failure modes, mechanisms, cause, effects severity of the fractionator column through its fourteen (14 sub-units(fractionator primary condenser, bottoms product cooler, debutanizer oil condenser, main fractionator, main fractionator oil drum, main fractionator reflux drum, heavy naphtha exchanger, heavy cycle oil exchanger, bottoms exchanger, BFW heater, steam generator, stripper reboiler, debutanizer reboiler, top reflux pumps. Both quantitative and qualitative criticality analyses (CA were used to determine the effectiveness and reliability of the unit (Fractionator column. For the qualitative analysis, items risk priority number (RPN were computed and it was found that, six (6 of the sub-units (feed/ main fractionator bottoms exchanger, main fractionator reflux drum, main fractionator bottoms pumps, feed/ heavy naphtha exchanger, main fractionator, and main fractionator bottoms/BFW heater had their RPN>300, with feed/ main fractionator bottoms exchanger having the highest RPN of 460. For the quantitative analysis, items criticality number (Cr were computed and it was found that most of the sub-units had their Cr>0.002. In addition, the results of the criticality matrix showed that, fifteen (15 out of the twenty nine (29 failure modes identifiedwere above or closely below the criticality line. Therefore, the effectiveness and reliability of the unit is low. As such, sub