WorldWideScience

Sample records for head failure modes

  1. Failure Modes

    DEFF Research Database (Denmark)

    Jakobsen, K. P.; Burcharth, H. F.; Ibsen, Lars Bo;

    1999-01-01

    The present appendix contains the derivation of ten different limit state equations divided on three different failure modes. Five of the limit state equations can be used independently of the characteristics of the subsoil, whereas the remaining five can be used for either drained or undrained...

  2. Damage mechanics - failure modes

    Energy Technology Data Exchange (ETDEWEB)

    Krajcinovic, D.; Vujosevic, M. [Arizona State Univ., Tempe, AZ (United States)

    1996-12-31

    The present study summarizes the results of the DOE sponsored research program focused on the brittle failure of solids with disordered microstructure. The failure is related to the stochastic processes on the microstructural scale; namely, the nucleation and growth of microcracks. The intrinsic failure modes, such as the percolation, localization and creep rupture, are studied by emphasizing the effect of the micro-structural disorder. A rich spectrum of physical phenomena and new concepts that emerges from this research demonstrates the reasons behind the limitations of traditional, deterministic, and local continuum models.

  3. 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.

  4. Failure Mode/Mechanism Distributions

    Science.gov (United States)

    1991-09-01

    nsc. Modas /Mach Dist. Dist. Suurce(,%)/Detai19 Bolt, MahineSources :1 Brcikon 𔃺.1% 59.0% Broken Bolt(s) (25j01-(000,Qty:l) C25101-000,Qty:Ij., Part...Center (RAC) * 201 Mill St., Rome, NY 13440 * 315-337-0900 3-114 Failure Distribution Summaries FMD-91 ? art Failure Norm Fail Data Docm. Mode/Moch Dist... Deco . Mode/Mech Dist. Dist. Source(s)/Details Lamp,Bulb Sourcent 4 Lamp Failure 68.8% 53.8% Light Bulb Failure (23038-00l,Qty:3) (23038-004,Qty:l

  5. Rubble Mound Breakwater Failure Modes

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Z., Liu

    1995-01-01

    The RMBFM-Project (Rubble Mound Breakwater Failure Modes) is sponsored by the Directorate General XII of the Commission of the European Communities under the Contract MAS-CT92- 0042, with the objective of contributing to the development of rational methods for the design of rubble mound breakwaters...... modes, plus development of related partial coefficients which make it possible to design according to preselected reliability levels. Due to limited space only the major activities are described....

  6. Photovoltaic failure and degradation modes: PV failure and degradation modes

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk C. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Silverman, Timothy J. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Wohlgemuth, John H. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; Kurtz, Sarah R. [National Renewable Energy Laboratory (NREL), 15013 Denver West Parkway Golden Colorado 80401 USA; VanSant, Kaitlyn T. [Colorado School of Mines, 1500 Illinois Street Golden Colorado 8040 USA

    2017-01-30

    The extensive photovoltaic field reliability literature was analyzed and reviewed. Future work is prioritized based upon information assembled from recent installations, and inconsistencies in degradation mode identification are discussed to help guide future publication on this subject. Reported failure rates of photovoltaic modules fall mostly in the range of other consumer products; however, the long expected useful life of modules may not allow for direct comparison. In general, degradation percentages are reported to decrease appreciably in newer installations that are deployed after the year 2000. However, these trends may be convoluted with varying manufacturing and installation quality world-wide. Modules in hot and humid climates show considerably higher degradation modes than those in desert and moderate climates, which warrants further investigation. Delamination and diode/j-box issues are also more frequent in hot and humid climates than in other climates. The highest concerns of systems installed in the last 10 years appear to be hot spots followed by internal circuitry discoloration. Encapsulant discoloration was the most common degradation mode, particularly in older systems. In newer systems, encapsulant discoloration appears in hotter climates, but to a lesser degree. Thin-film degradation modes are dominated by glass breakage and absorber corrosion, although the breadth of information for thin-film modules is much smaller than for x-Si.

  7. Failure Modes of thin supported Membranes

    DEFF Research Database (Denmark)

    Hendriksen, Peter Vang; Høgsberg, J.R.; Kjeldsen, Ane Mette;

    2007-01-01

    Four different failure modes relevant to tubular supported membranes (thin dense films on a thick porous support) were analyzed. The failure modes were: 1) Structural collapse due to external pressure 2) burst of locally unsupported areas, 3) formation of surface cracks in the membrane due to TEC......-mismatches, and finally 4) delamination between membrane and support due to expansion of the membrane on use. Design criteria to minimize risk of failure by the four different modes are discussed. The theoretical analysis of the two last failure modes is compared to failures observed on actual components....

  8. Failure modes of composite sandwich beams

    Directory of Open Access Journals (Sweden)

    Gdoutos E.

    2008-01-01

    Full Text Available A thorough investigation of failure behavior of composite sandwich beams under three-and four-point bending was undertaken. The beams were made of unidirectional carbon/epoxy facings and a PVC closed-cell foam core. The constituent materials were fully characterized and in the case of the foam core, failure envelopes were developed for general two-dimensional states of stress. Various failure modes including facing wrinkling, indentation failure and core failure were observed and compared with analytical predictions. The initiation, propagation and interaction of failure modes depend on the type of loading, constituent material properties and geometrical dimensions.

  9. Failure modes in surface micromachined microelectromechanical actuators

    Energy Technology Data Exchange (ETDEWEB)

    Miller, S.L.; Rodgers, M.S.; LaVigne, G.; Sniegowski, J.J.; Clews, P.; Tanner, D.M.; Peterson, K.A.

    1998-03-01

    In order for the rapidly emerging field of MicroElectroMechanical Systems (MEMS) to meet its extraordinary expectations regarding commercial impact, issues pertaining to how they fail must be understood. The authors identify failure modes common to a broad range of MEMS actuators, including adhesion (stiction) and friction induced failures caused by improper operational methods, mechanical instabilities, and electrical instabilities. Demonstrated methods to mitigate these failure modes include implementing optimized designs, model based operational methods, and chemical surface treatments.

  10. 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.

  11. 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.

  12. 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.

  13. A study of rock bolting failure modes

    Institute of Scientific and Technical Information of China (English)

    Cao Chen; Jan Nemcik; Ren Ting; Naj Aziz

    2013-01-01

    Rock bolting has advanced rapidly during the past 4 decades due to a better understanding of load transfer mechanisms and advances made in the bolt system technology.Bolts are used as permanent and temporary support systems in tunnelling and mining operations.A review of has indicated that three systems of reinforcement devices have evolved as part of rock bolt and ground anchor while the rock is not generally thought of as being a component of the reinforcement system.A classification of rock bolting reinforcement systems is presented,followed by the fundamental theory of the load transfer mechanism.The failure mode of two phases of rock bolting system is formularised.The failure modes of cable bolting are discussed using a bond strength model as well as an iterative method.Finally,the interfacial shear stress model for ribbed bar is introduced and a closed form solution is obtained using a tri-line stress strain relationship.

  14. 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.

  15. Head-Tail Modes for Strong Space Charge

    Energy Technology Data Exchange (ETDEWEB)

    Burov, Alexey

    2008-12-01

    Head-tail modes are described here for the space charge tune shift significantly exceeding the synchrotron tune. General equation for the modes is derived. Spatial shapes of the modes, their frequencies, and coherent growth rates are explored. The Landau damping rates are also found. Suppression of the transverse mode coupling instability by the space charge is explained.

  16. Modelling the failure modes in geobag revetments.

    Science.gov (United States)

    Akter, A; Crapper, M; Pender, G; Wright, G; Wong, W S

    2012-01-01

    In recent years, sand filled geotextile bags (geobags) have been used as a means of long-term riverbank revetment stabilization. However, despite their deployment in a significant number of locations, the failure modes of such structures are not well understood. Three interactions influence the geobag performance, i.e. geobag-geobag, geobag-water flow and geobag-water flow-river bank. The aim of the research reported here is to develop a detailed understanding of the failure mechanisms in a geobag revetment using a discrete element model (DEM) validated by laboratory data. The laboratory measured velocity data were used for preparing a mapped velocity field for a coupled DEM simulation of geobag revetment failure. The validated DEM model could identify well the critical bag location in varying water depths. Toe scour, one of the major instability factors in revetments, and its influence on the bottom-most layer of the bags were also reasonably represented in this DEM model. It is envisaged that the use of a DEM model will provide more details on geobag revetment performance in riverbanks.

  17. Failure modes of lead/acid batteries

    Science.gov (United States)

    Culpin, B.; Rand, D. A. J.

    , have been afforded little discussion. Progressive life-limiting factors encountered with flooded-electrolyte batteries are discussed in detail. These are mainly associated with degradation of the positive plate, the negative plate and the separator. The technology of valve-regulated (i.e., immobilized-electrolyte) batteries is still at an early stage compared with that of flooded designs and, consequently, published information on failure modes is very limited. Nevertheless, based on the reports that are available and the authors' own knowledge, it is possible to make estimates of the major and minor causes of failure (note, these will also occur in flooded systems, but with shifted emphasis). Grid corrosion and growth are generally considered to be of major importance. Both negative-plate sulphation and water loss are also of concern, particularly in cycling applications. By contrast, the traditional problems associated mossing and dendritic growth of the active material should be reduced in valve-regulated batteries.

  18. Gearbox Typical Failure Modes, Detection, and Mitigation Methods (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, S.

    2014-01-01

    This presentation was given at the AWEA Operations & Maintenance and Safety Seminar and focused on what the typical gearbox failure modes are, how to detect them using detection techniques, and strategies that help mitigate these failures.

  19. 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.

  20. 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.

  1. 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

  2. CSM RCS Design Considerations and Failure Modes

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    Objectives include: a) Define major Command and Service Module (CSM) design considerations; b) List Command Module (CM) RCS failures and lessons learned; and c) List Service Module (SM) RCS failures and lessons learned.

  3. 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)

  4. 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.

  5. 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.

  6. Wind Turbine Gearbox Failure Modes - A Brief (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, S.; McDade, M.; Errichello, R.

    2011-10-01

    Wind turbine gearboxes are not always meeting 20-year design life. Premature failure of gearboxes increases cost of energy, turbine downtime, unplanned maintenance, gearbox replacement and rebuild, and increased warranty reserves. The problem is widespread, affects most Original Equipment Manufacturers, and is not caused by manufacturing practices. There is a need to improve gearbox reliability and reduce turbine downtime. The topics of this presentation are: GRC (Gearbox Reliability Collaborative) technical approach; Gearbox failure database; Recorded incidents summary; Top failure modes for bearings; Top failure modes for gears; GRC test gearbox; Bearing nomenclature; Test history; Real damage; Gear sets; Bearings; Observations; and Summary. 5 refs.

  7. 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

  8. 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.

  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. 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.

  11. Predicting Modes and Displacements of Seismic Rock Slope Failures

    Science.gov (United States)

    Gibson, M. D.; Wartman, J.; Keefer, D. K.; Maclaughlin, M.; Arnold, L.; Applegate, K. N.; Smith, S.; Adams, S.

    2013-12-01

    Seismically induced rock slope failures have resulted in billions of dollars of economic damage and enormous loss of life throughout the world. Accurate prediction of the triggering and run out of these failures is elusive for a variety of reasons, including knowledge of the physical modes of failure. Our research explores the potential failure modes of an idealized rigid rock block and expands the modes typically considered to include not only sliding but also toppling (pure forward rotation) and slumping (combined backward rotation and translation). The yield acceleration (or minimum inertial acceleration to cause block movement) for slumping, similar to toppling, is found to be lower than for pure translational sliding. These yield accelerations indicate the initial modes of rock block failure; however, they do not always predict the ultimate failure mode. To predict the final failure modes, the results of discrete element numerical analyses were compared to pseudo static yield acceleration to develop a seismic failure mode decision-making chart based on block geometry and interface friction. With regard to seismic displacement predictions, current simplified models predicting ultimate displacement of a mass under seismic conditions are limited to purely translating, sliding blocks (i.e. Newmark's sliding block method). Our modeling introduces additional simplified analyses to predict ultimate displacement in toppling and slumping modes as well. Important findings from these new methods are that the magnitude of seismically-induced displacement is dependent on the size of the block (or failure mass) and that as the yield acceleration decreases the seismically induced displacements increase. We plan to map these tools into analyses that evaluate rock slope systems with complex geology and geotechnical characteristics. It is envisioned that the decision chart, which predicts the initial and ultimate modes of failure based on block geometry and interface friction

  12. 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.

  13. Failure mode classification of reinforced concrete column using Fisher method

    Institute of Scientific and Technical Information of China (English)

    戚永乐; 韩小雷; 季静

    2013-01-01

    In order to apply the performance-based seismic design, an engineer must first find out whether the column is expected to fail in shear before or after flexural yielding. According to column failure characteristics and failure mode of reinforced concrete column, the UW-PEER structure performance database was discussed and analyzed. In order to investigate the relevance of failure mode and factors such as longitudinal reinforcement ratio, transverse reinforcement ratio, hoop spacing to depth ratio, aspect ratio, shearing resistance demand to shear capacity ratio and axial load ratio, Fisher’s discriminant analysis(FDA) of the above factors was carried out. A discriminant function was developed to identify column failure mode. Results show that three factors, i.e., Vp /Vn, hoop spacing to depth ratio and aspect ratio have important influence on the failure mode. The failure mode has less to do with longitudinal reinforcement ratio, transverse reinforcement ratio and axial load ratio. Through using these three factors and the model proposed, over 85.6% of the original grouped cases were correctly classified. The value of coefficient of Vp /Vn is the largest, which means that discriminant equation is most sensitive to the shearing resistance demand to shear capacity ratio.

  14. Maximum likelihood estimation for life distributions with competing failure modes

    Science.gov (United States)

    Sidik, S. M.

    1979-01-01

    The general model for the competing failure modes assuming that location parameters for each mode are expressible as linear functions of the stress variables and the failure modes act independently is presented. The general form of the likelihood function and the likelihood equations are derived for the extreme value distributions, and solving these equations using nonlinear least squares techniques provides an estimate of the asymptotic covariance matrix of the estimators. Monte-Carlo results indicate that, under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slightly biased, and the asymptotic covariances are rapidly approached.

  15. 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.

  16. 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%.

  17. 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.

  18. UAV Swarm Behavior Modeling for Early Exposure of Failure Modes

    Science.gov (United States)

    2016-09-01

    is present. If that is not feasible, the UAV should immediately reduce altitude and land. The landing method is a mission driven behavior that does...new operation to allow the nearest UAV to relieve the bingo fueled UAV. Once the new UAV arrives, the UAV experiencing the bingo fuel failure mode

  19. PV Degradation Curves: Non-Linearities and Failure Modes

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, Dirk C.; Silverman, Timothy J.; Sekulic, Bill; Kurtz, Sarah R.

    2016-09-03

    Photovoltaic (PV) reliability and durability have seen increased interest in recent years. Historically, and as a preliminarily reasonable approximation, linear degradation rates have been used to quantify long-term module and system performance. The underlying assumption of linearity can be violated at the beginning of the life, as has been well documented, especially for thin-film technology. Additionally, non-linearities in the wear-out phase can have significant economic impact and appear to be linked to different failure modes. In addition, associating specific degradation and failure modes with specific time series behavior will aid in duplicating these degradation modes in accelerated tests and, eventually, in service life prediction. In this paper, we discuss different degradation modes and how some of these may cause approximately linear degradation within the measurement uncertainty (e.g., modules that were mainly affected by encapsulant discoloration) while other degradation modes lead to distinctly non-linear degradation (e.g., hot spots caused by cracked cells or solder bond failures and corrosion). The various behaviors are summarized with the goal of aiding in predictions of what may be seen in other systems.

  20. 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.

  1. Failure mode interaction in fiber reinforced laminated composites

    Science.gov (United States)

    Prabhakar, Pavana

    A novel computational modeling framework to predict the compressive strength of fiber reinforced polymer matrix composite (FRPC) laminates has been presented. The model development has been motivated by a set of experimental results on the compression response of two different FRPCs. The model accounts for failure mode interaction between kink-banding and interface fracture (or delamination), which are observed in the experimental results. To reduce the size of the computational model, those interfaces that are most susceptible to delamination are first determined through a free-edge stress analysis. Furthermore, 0-axis layers, which are passive in the failure process are represented through an equivalent homogenized model, but the microstructural features of the on-axis layers (zero plies) are retained in the computational model. The predictions of the model matched well with the experimental observations, and they were found to accurately account for failure mechanism interactions. Therefore, this model has the potential to replace the need to carry out large numbers of tests to obtain the compressive strength allowable for FRPC laminates, the latter allowable being an essential element in the design of lightweight FRPC aerostructures. Furthermore, the thesis presents a new computational model to predict fiber/matrix splitting failure, a failure mode that is frequently observed in in-plane tensile failure of FRPC's. By considering a single lamina, this failure mechanism was seamlessly modeled through the development of a continuum-decohesive nite element (CDFE). The CDFE was motivated by the variational multiscale cohesive method (VMCM) presented earlier by Rudraraju et al. (2010) at the University of Michigan. In the CDFE, the transition from a continuum to a non-continuum is modeled directly (physically) without resorting to enrichment of the shape functions of the element. Thus, the CDFE is a natural merger between cohesive elements and continuum elements. The

  2. Effect of fiber-reinforced composites on the failure load and failure mode of composite veneers.

    Science.gov (United States)

    Turkaslan, Suha; Tezvergil-Mutluay, Arzu; Bagis, Bora; Vallittu, Pekka k; Lassila, Lippo V J

    2009-09-01

    This study compared the initial and final failure loads and failure modes of indirect resin composite laminate veneers with and without fiber reinforcement. Forty intact lower canines received standard laminate preparations and were randomly assigned into four test groups (n=10). In Group 1, indirect resin composite veneers were repaired with two layers of preimpregnated bidirectional glass fiber weave and a restorative composite; in Group 2, with a layer of preimpregnated unidirectional glass fibers and a restorative composite; and in Group 3, with an experimental semi-IPN matrix composed of multidirectional short glass fibers. Indirect resin composite veneers without any fiber reinforcement were used as control (Group 4). All specimens were thermocycled and tested with a universal testing machine. On the final failure load, there were no statistically significant differences (p>0.05) among the test groups. Within each group, pairwise comparison of initial and final failure loads revealed statistically significant differences (p0.05). On failure mode, unreinforced specimens showed instantaneous failure, whereas reinforced specimens mostly demonstrated elongated failure.

  3. Failure modes of PDC cutters under different loads

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The capability of several types of flat PDC cutters to withstand combined loads were tested and evaluated by the impact and cutting of single PDC cutter on granite in a linear impact-cutting table.The primary failure modes of PDC cutters withstading different combined loads wrer investigated and analyzed.The suggestions of enhancing PDC cutters to be suitables for drilling very hard rock have been made.

  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. Seismic failure modes and seismic safety of Hardfill dam

    Institute of Scientific and Technical Information of China (English)

    Kun XIONG; Yong-hong WENG; Yun-long HE

    2013-01-01

    Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and greater seismic safety.

  6. [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.

  7. 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.

  8. 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

  9. Breathing mode influence on craniofacial development and head posture.

    Science.gov (United States)

    Chambi-Rocha, Annel; Cabrera-Domínguez, Mª Eugenia; Domínguez-Reyes, Antonia

    2017-08-14

    The incidence of abnormal breathing and its consequences on craniofacial development is increasing, and is not limited to children with adenoid faces. The objective of this study was to evaluate the cephalometric differences in craniofacial structures and head posture between nasal breathing and oral breathing children and teenagers with a normal facial growth pattern. Ninety-eight 7-16 year-old patients with a normal facial growth pattern were clinically and radiographically evaluated. They were classified as either nasal breathing or oral breathing patients according to the predominant mode of breathing through clinical and historical evaluation, and breathing respiratory rate predomination as quantified by an airflow sensor. They were divided in two age groups (G1: 7-9) (G2: 10-16) to account for normal age-related facial growth. Oral breathing children (8.0±0.7 years) showed less nasopharyngeal cross-sectional dimension (MPP) (p=0.030), whereas other structures were similar to their nasal breathing counterparts (7.6±0.9 years). However, oral breathing teenagers (12.3±2.0 years) exhibited a greater palate length (ANS-PNS) (p=0.049), a higher vertical dimension in the lower anterior face (Xi-ANS-Pm) (p=0.015), and a lower position of the hyoid bone with respect to the mandibular plane (H-MP) (p=0.017) than their nasal breathing counterparts (12.5±1.9 years). No statistically significant differences were found in head posture. Even in individuals with a normal facial growth pattern, when compared with nasal breathing individuals, oral breathing children present differences in airway dimensions. Among adolescents, these dissimilarities include structures in the facial development and hyoid bone position. Copyright © 2017 Sociedade Brasileira de Pediatria. Published by Elsevier Editora Ltda. All rights reserved.

  10. MEMS Reliability: Infrastructure, Test Structures, Experiments, and Failure Modes

    Energy Technology Data Exchange (ETDEWEB)

    TANNER,DANELLE M.; SMITH,NORMAN F.; IRWIN,LLOYD W.; EATON,WILLIAM P.; HELGESEN,KAREN SUE; CLEMENT,J. JOSEPH; MILLER,WILLIAM M.; MILLER,SAMUEL L.; DUGGER,MICHAEL T.; WALRAVEN,JEREMY A.; PETERSON,KENNETH A.

    2000-01-01

    The burgeoning new technology of Micro-Electro-Mechanical Systems (MEMS) shows great promise in the weapons arena. We can now conceive of micro-gyros, micro-surety systems, and micro-navigators that are extremely small and inexpensive. Do we want to use this new technology in critical applications such as nuclear weapons? This question drove us to understand the reliability and failure mechanisms of silicon surface-micromachined MEMS. Development of a testing infrastructure was a crucial step to perform reliability experiments on MEMS devices and will be reported here. In addition, reliability test structures have been designed and characterized. Many experiments were performed to investigate failure modes and specifically those in different environments (humidity, temperature, shock, vibration, and storage). A predictive reliability model for wear of rubbing surfaces in microengines was developed. The root causes of failure for operating and non-operating MEMS are discussed. The major failure mechanism for operating MEMS was wear of the polysilicon rubbing surfaces. Reliability design rules for future MEMS devices are established.

  11. Reliability models of belt drive systems under slipping failure mode

    Directory of Open Access Journals (Sweden)

    Peng Gao

    2017-01-01

    Full Text Available Conventional reliability assessment and reliability-based optimal design of belt drive are based on the stress–strength interference model. However, the stress–strength interference model is essentially a static model, and the sensitivity analysis of belt drive reliability with respect to design parameters needs further investigations. In this article, time-dependent factors that contribute the dynamic characteristics of reliability are pointed out. Moreover, dynamic reliability models and failure rate models of belt drive systems under the failure mode of slipping are developed. Furthermore, dynamic sensitivity models of belt drive reliability based on the proposed dynamic reliability models are proposed. In addition, numerical examples are given to illustrate the proposed models and analyze the influences of design parameters on dynamic characteristics of reliability, failure rate, and sensitivity functions. The results show that the statistical properties of design parameters have different influences on reliability and failure rate of belt drive in cases of different values of design parameters and different operational durations.

  12. 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.

  13. 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.

  14. 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

  15. Microstructural Study of IF-WS2 Failure Modes

    Directory of Open Access Journals (Sweden)

    Jamie Cook

    2014-07-01

    Full Text Available This manuscript summarizes the failure mechanisms found in inorganic fullerene-type tungsten disulfide (IF-WS2 nanoparticles treated with diverse pressure loading methods. The approaches utilized to induce failure included: the use of an ultrasonic horn, the buildup of high pressures inside a shock tube which created a shock wave that propagated and impinged in the sample, and impact with military rounds. After treatment, samples were characterized using electron microscopy, powder X-ray diffraction, energy dispersive X-ray spectroscopy, and surface area analysis. The microstructural changes observed in the IF-WS2 particulates as a consequence of the treatments could be categorized in two distinct fracture modes. The most commonly observed was the formation of a crack at the particles surface followed by a phase transformation from the 3D cage-like structures into the 2D layered polymorphs, with subsequent agglomeration of the plate-like sheets to produce larger particle sizes. The secondary mechanism identified was the incipient delamination of IF-WS2. We encountered evidence that the IF-WS2 structure collapse initiated in all cases at the edges and vertices of the polyhedral particles, which acted as stress concentrators, independent of the load application mode or its duration.

  16. Seismic failure modes and seismic safety of Hardfill dam

    Directory of Open Access Journals (Sweden)

    Kun XIONG

    2013-04-01

    Full Text Available Based on microscopic damage theory and the finite element method, and using the Weibull distribution to characterize the random distribution of the mechanical properties of materials, the seismic response of a typical Hardfill dam was analyzed through numerical simulation during the earthquakes with intensities of 8 degrees and even greater. The seismic failure modes and failure mechanism of the dam were explored as well. Numerical results show that the Hardfill dam remains at a low stress level and undamaged or slightly damaged during an earthquake with an intensity of 8 degrees. During overload earthquakes, tensile cracks occur at the dam surfaces and extend to inside the dam body, and the upstream dam body experiences more serious damage than the downstream dam body. Therefore, under the seismic conditions, the failure pattern of the Hardfill dam is the tensile fracture of the upstream regions and the dam toe. Compared with traditional gravity dams, Hardfill dams have better seismic performance and greater seismic safety.

  17. Failure modes and materials design for biomechanical layer structures

    Science.gov (United States)

    Deng, Yan

    Ceramic materials are finding increasing usage in the area of biomechanical replacements---dental crowns, hip and bone implants, etc.---where strength, wear resistance, biocompatibility, chemical durability and even aesthetics are critical issues. Aesthetic ceramic crowns have been widely used in dentistry to replace damaged or missing teeth. However, the failure rates of ceramic crowns, especially all-ceramic crowns, can be 1%˜6% per year, which is not satisfactory to patients. The materials limitations and underlying fracture mechanisms of these prostheses are not well understood. In this thesis, fundamental fracture and damage mechanisms in model dental bilayer and trilayer structures are studied. Principle failure modes are identified from in situ experimentation and confirmed by fracture mechanics analysis. In bilayer structures of ceramic/polycarbonate (representative of ceramic crown/dentin structure), three major damage sources are identified: (i) top-surface cone cracks or (ii) quasiplasticity, dominating in thick ceramic bilayers; (iii) bottom-surface radial cracks, dominating in thin ceramic bilayers. Critical load P for each damage mode are measured in six dental ceramics: Y-TZP zirconia, glass-infiltrated zirconia and alumina (InCeram), glass-ceramic (Empress II), Porcelain (Mark II and Empress) bonded to polymer substrates, as a function of ceramic thickness d in the range of 100 mum to 10 mm. P is found independent of d for mode (i) and (ii), but has a d 2 relations for mode (iii)---bottom surface radial cracking. In trilayer structures of glass/core-ceramic/polycarbonate (representing veneer porcelain/core/dentin structures), three inner fracture origins are identified: radial cracks from the bottom surface in the (i) first and (ii) second layers; and (iii) quasiplasticity in core-ceramic layer. The role of relative veneer/core thickness, d1/d 2 and materials properties is investigated for three core materials with different modulus (114--270GPa

  18. The influence of temperature on failure modes for Solnhofen limestone

    Science.gov (United States)

    Zhu, W.; Xiao, X.; Evans, B.

    2003-04-01

    The initiation and growth of shear localization is of fundamental importance in understanding the mechanics of earthquake and faulting. Because dilatancy is generally observed as a precursor to brittle faulting, early laboratory and theoretical studies tended to focus on dilatant materials. However, recent laboratory studies demonstrated that investigating the complex interplay between dilatancy and compaction is crucial in understanding this brittle failure phenomenon in many porous rocks. In this study, we deformed Solnhofen limestone with initial porosity of 4.5% at temperatures of 473, 523, 573 and 673 K, at confining pressures (argon) of 70 to 300 MPa, and a constant pore pressure (distilled water or argon) of 50 MPa. In situ measurements of dilatancy, permeability and storage capacity were performed with Argon gas as pore fluid. To elucidate the mechanisms that control the failure modes in Solnhofen limestone, both SEM and TEM studies are conducted on the deformed samples. Our experimental results indicate that the deformation mechanisms and failure modes are sensitive to both pressure and temperature conditions. At low pressures and temperatures, significant amount of strain softening and an abrupt stress drop were observed during localization. However, at higher pressure and temperature, the localization process became rather progressive, with strain softening and dilatancy accumulating over large amount of axial strain. Our experimental results also demonstrate that shear-enhanced compaction can evolve to dilatant cataclasis at elevated temperature, which is consistent with previous low temperature experimental data (Baud et al., 2000). This implies that stress-induced compaction and dilation should not be viewed as mutually exclusive processes. Testing existing theoretical models using well-constraint laboratory studies is the critical first step towards a better understanding of the physics of deformation processes. Following the localization model

  19. 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

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

    Science.gov (United States)

    Corn, Aimee

    also indicated there was a potential for permanent horizontal displacement along the dam/foundation interface. The horizontal movement was not considered large enough to develop a shear failure of the tendons at the project. The results from this study indicate demand to capacity ratios (DCR) of 0.79 for the anchor head, 0.75 for the tendon, and 0.63 for the foundation cone failure, and a potential displacement of 0.33 inches, which is not large enough to shear the tendon. The methods developed are appropriate for the evaluation of the tensile and shear failure modes for the PTA tendons. Based on the results, it would appear that shear failure of the tendon is a more likely failure mechanism. Thus, shear failure of the tendon should be a focus of seismic evaluations.

  1. 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.

  2. Influence of crosshead speed on failure load and failure mode of restored maxillary premolars

    Directory of Open Access Journals (Sweden)

    Lucas Zago NAVES

    2016-01-01

    Full Text Available We analyzed the effect of the crosshead speed of an applied load on failure load and failure mode of restored human premolars. Fifty intact, noncarious human premolars were selected. Class II mesio-occlusodistal preparations were made with a water-cooled high-speed preparation machine, and the teeth were restored with composite resin. The specimens were divided into five groups (n = 10 each and tested individually in a mechanical testing machine, in which a 6.0-mm-diameter steel cylinder was mounted to vary the crosshead speed: v0.5: 0.5 mm/min; v1: 1.0 mm/min; v2.5: 2.5 mm/min; v5: 5.0 mm/min; and v10: 10.0 mm/min. The cylinder contacted the facial and lingual ridges beyond the margins of the restorations. Peak load to fracture was measured for each specimen (N. The means were calculated and analyzed with one-way analysis of variance followed by Tukey's test (a = 0.05. The mean load at failure values were (N as follows: v0.5, 769.4 ± 174.8; v1, 645.2 ± 115.7; v5, 614.3 ± 126.0; v2.5, 609.2 ± 208.1; and v10, 432.5 ± 136.9. The fracture modes were recorded on the basis of the degree of the tooth structural and restorative damage: (I fracture of the restoration involving a small portion of the tooth; (II fractures involving the coronal portion of the tooth with cohesive failure of the composite resin; (III oblique tooth and restoration fracture with periodontal involvement; and (IV vertical root and coronal fracture. Varying crosshead speeds of 0.5–5.0 mm/min did not influence the failure load of restored maxillary premolars; however, increasing the crosshead speed to 10 mm/min decreased the failure load values and the degree of tooth structural damage.

  3. Failure mode transition in AHSS resistance spot welds. Part I. Controlling factors

    Energy Technology Data Exchange (ETDEWEB)

    Pouranvari, M., E-mail: mpouranvari@yahoo.com [Young Researchers Club, Dezful Branch, Islamic Azad University, Dezful (Iran, Islamic Republic of); Marashi, S.P.H. [Mining and Metallurgical Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2011-11-15

    Highlights: {yields} Interfacial to pullout failure mode transition for AHSS RSWs is studied. {yields} An analytical mode is proposed to predict failure mode of AHSS RSWs. {yields} Hardness characteristics of RSWs plays key role in the failure mode transition. - Abstract: Failure mode of resistance spot welds is a qualitative indicator of weld performance. Two major types of spot weld failure are pull-out and interfacial fracture. Interfacial failure, which typically results in reduced energy absorption capability, is considered unsatisfactory and industry standards are often designed to avoid this occurrence. Advanced High Strength Steel (AHSS) spot welds exhibit high tendency to fail in interfacial failure mode. Sizing of spot welds based on the conventional recommendation of 4t{sup 0.5} (t is sheet thickness) does not guarantee the pullout failure mode in many cases of AHSS spot welds. Therefore, a new weld quality criterion should be found for AHSS resistance spot welds to guarantee pull-out failure. The aim of this paper is to investigate and analyze the transition between interfacial and pull-out failure modes in AHSS resistance spot welds during the tensile-shear test by the use of analytical approach. In this work, in the light of failure mechanism, a simple analytical model is presented for estimating the critical fusion zone size to prevent interfacial fracture. According to this model, the hardness ratio of fusion zone to pull-out failure location and the volume fraction of voids in fusion zone are the key metallurgical factors governing type of failure mode of AHSS spot welds during the tensile-shear test. Low hardness ratio and high susceptibility to form shrinkage voids in the case of AHSS spot welds appear to be the two primary causes for their high tendency to fail in interfacial mode.

  4. [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.

  5. Failure to Obtain Computed Tomography Imaging in Head Trauma: A Review of Relevant Case Law.

    Science.gov (United States)

    Lindor, Rachel A; Boie, Eric T; Campbell, Ronna L; Hess, Erik P; Sadosty, Annie T

    2015-12-01

    The objectives were to describe lawsuits against providers for failing to order head computed tomography (CT) in cases of head trauma and to determine the potential effects of available clinical decision rules (CDRs) on each lawsuit. The authors collected jury verdicts, settlements, and court opinions regarding alleged malpractice for failure to order head CT in the setting of head trauma from 1972 through February 2014 from an online legal research tool (WestlawNext). Data were abstracted onto a standardized data form. The performance of five CDRs was evaluated. Sixty relevant cases were identified (52 adult, eight children). Of 48 cases with known outcomes, providers were found negligent in 10 cases (six adult, four pediatric), settled in 11 cases (nine adult, two pediatric), and were found not liable in 27 cases. In all 10 cases in which providers were found negligent, every applicable CDR studied would have indicated the need for head CT. In all eight cases involving children, the applicable CDR would have suggested the need for head CT or observation. A review of legal cases reported in a major online legal research system revealed 60 lawsuits in which providers were sued for failing to order head CTs in cases of head trauma. In all cases in which providers were found negligent, CT imaging or observation would have been indicated by every applicable CDR. © 2015 by the Society for Academic Emergency Medicine.

  6. Is neonatal head circumference related to caesarean section for failure to progress?

    Science.gov (United States)

    de Vries, Bradley; Bryce, Bianca; Zandanova, Tatiana; Ting, Jason; Kelly, Patrick; Phipps, Hala; Hyett, Jon A

    2016-12-01

    There is global concern about rising caesarean section rates. Identification of risk factors could lead to preventative measures. To describe the association between neonatal head circumference and (i) caesarean section for failure to progress, (ii) intrapartum caesarean section overall. This was a retrospective cohort study of 11 687 singleton live births with cephalic presentation, attempted vaginal birth and at least 37 completed weeks gestation from January 2005 to June 2009. Neonatal head circumference was grouped into quartiles and multiple logistic regressions performed. The rates of caesarean section for failure to progress were 4.1, 6.4, 8.8 and 14.3% in successive head circumference quartiles. Rates of intrapartum caesarean section overall were 8.7, 12.1, 15.8 and 21.5%. The odds ratios for caesarean section for failure to progress were: 1.00, 1.33 (95% CI 1.02- 1.73), 1.54 (1.18-2.02) and 1.93 (1.44-2.57) for successive head circumference quartiles after adjusting for multiple demographic and clinical factors. The adjusted odds ratios for intrapartum caesarean section for any indication were: 1.00, 1.52 (95% CI 1.24-1.87), 1.99 (1.62-2.46) and 2.38 (1.89-3.00), respectively. There is a strong positive relationship between head circumference quartile and both caesarean section for failure to progress and caesarean for any indication. If this finding is confirmed using ultrasound measurements, there is potential for head circumference to be incorporated into predictive models for intrapartum caesarean section with a view to offering interventions to reduce the risk of caesarean section. © 2016 The Royal Australian and New Zealand College of Obstetricians and Gynaecologists.

  7. On a common critical state in localized and diffuse failure modes

    Science.gov (United States)

    Zhu, Huaxiang; Nguyen, Hien N. G.; Nicot, François; Darve, Félix

    2016-10-01

    Accurately modeling the critical state mechanical behavior of granular material largely relies on a better understanding and characterizing the critical state fabric in different failure modes, i.e. localized and diffuse failure modes. In this paper, a mesoscopic scale is introduced, in which the organization of force-transmission paths (force-chains) and cells encompassed by contacts (meso-loops) can be taken into account. Numerical drained biaxial tests using a discrete element method are performed with different initial void ratios, in order to investigate the critical state fabric on the meso-scale in both localized and diffuse failure modes. According to the displacement and strain fields extracted from tests, the failure mode and failure area of each specimen are determined. Then convergent critical state void ratios are observed in failure area of specimens. Different mechanical features of two kinds of meso-structures (force-chains and meso-loops) are investigated, to clarify whether there exists a convergent meso-structure inside the failure area of granular material, as the signature of critical state. Numerical results support a positive answer. Failure area of both localized and diffuse failure modes therefore exhibits the same fabric in critical state. Hence, these two failure modes prove to be homological with respect to the concept of the critical state.

  8. Failure Modes of Lead Free Solder Bumps Formed by Induction Spontaneous Heating Reflow

    Institute of Scientific and Technical Information of China (English)

    Mingyu LI; Hongbo XU; Jongmyung KIM; Hongbae KIM

    2007-01-01

    The shear failure modes and respective failure mechanism of Sn3.5Ag and Sn3.0Ag0.5Cu lead-free solder bumping on Au/Ni/Cu metallization formed by induction spontaneous heating reflow process have been investigated through the shear test after aging at 120℃ for 0, 1, 4, 9 and 16 d. Different typical shear failure behaviors have been found in the loading curves (shear force vs displacement). From the results of interfacial morphology analysis of the fracture surfaces and cross-sections, two main typical failure modes have been identified. The probabilities of the failure modes occurrence are inconsistent when the joints were aged for different times. The evolution of the brittle Ni3Sn4 and Cu-Ni-Au-Sn layers and the grains coarsening of the solder bulk are the basic reasons for the change of shear failure modes.

  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. 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.

  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. MOM Failure Modes: An In-Depth Look at Metal Ions and Implant Wear

    Directory of Open Access Journals (Sweden)

    Tom Donaldson, MD

    2014-03-01

    Full Text Available Contemporary MOM bearings (large-diameter heads offered the perceived benefits of much greater range of motion and greater stability with reduced risk of impingement and dislocation. A variety of design and Both positive [1-3] and negative reports [4-8] have now emerged with regard to total hip arthroplasty (THA and resurfacing arthroplasty. As a result, there has been an avalanche of studies focused on critical issues such as: surgical positioning, shallow cups (face angles 144-170° [9-11] and “edge loading”. [5,7,12-17] However, there are several, possibly synergistic, risk scenarios that could trigger adverse MOM wear and very little progress has been made in understanding such interacting parameters. In an effort to understand the role of metal ion analysis and how it relates to revision surgery and implant wear, selected MOM revised cases were reviewed [28]. Retrieval data was included in conjunction with metal ion analyses and intraoperative observations to determine various failure modes.  We suggest MOM devices that are well fixed but fail after 2 years can be classified into one of six modes: (i normal, (ii allergic reaction, (iii 3rd body wear, (iv repetitive subluxation with metal impingement, (v multi-directional subluxation with soft tissue impingement, and (vi repetitive subluxation with soft tissue impingement.

  13. Effect of Fiber Orientation Angle on the Failure Mode of Pin Jointed Laminated Composite Plates

    Directory of Open Access Journals (Sweden)

    Kadir TURAN

    2010-02-01

    Full Text Available In this study, the major aim is to investigate change effects of fiber orientation angles on the failure loads and failure modes for the pin jointed laminated composite plates. In the analysis, laminated composite plates with epoxy matrix resin reinforced unidirectional carbon fibers are used. The ply arrangements are chosen [?0]4 and ?; fiber reinforced angle changes from 00 to 900 with 150 increments. The failure load and failure mode are analyzed experimentally and numerically. In the numerical analysis Ansys program is used. In the program, material properties are degraded using APDL code which is written for progressive failure analysis and contains Hashin failure criteria for laminated composite plates. In the experimental study, the maximum failure load for [150]4 laminae cofiguration, 749.917 N and minimum failure load for [600]4, 467.483 N laminae configuration are obtained. A good agreement between experimental and numerical solution is obtained.

  14. 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.

  15. Head-Positioning Control Using Virtual Resonant Modes in a Hard Disk Drive

    Science.gov (United States)

    Atsumi, Takenori

    In conventional control systems in hard disk drives, it is difficult to compensate for disturbances above the primary mechanical resonance. In this paper, a design method that uses a virtual resonant mode in head-positioning systems of hard disk drives was developed. The virtual resonant mode is a digital filter that works like a mechanical resonant mode. Using the proposed method, stable resonant modes in a control system can be designed with a high degree of accuracy to compensate for disturbances whose frequencies are higher than that of the primary mechanical resonance. Application of this method to a hard disk drive showed that it significantly suppresses disturbances beyond the primary mechanical resonance.

  16. Lunar Module Electrical Power System Design Considerations and Failure Modes

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    This slide presentation reviews the design and redesign considerations of the Apollo lunar module electrical power system. Included in the work are graphics showing the lunar module power system. It describes the in-flight failures, and the lessons learned from these failures.

  17. Acute renal failure following contrast injection for head computerized tomography in two patients with diabetic nephropathy

    Energy Technology Data Exchange (ETDEWEB)

    Matsunaga, H.; Sando, H.; Nunokawa, T.; Murakami, T.; Miyakawa, Y. (Tokyo Univ. (Japan). Faculty of Medicine)

    1981-10-01

    Two cases of diabetes mellitus with renal and retinal involvement developed acute renal failure after undergoing head computerized tomography. The first case was a 62-year-old male who had been diagnosed as having diabetes 25 years before. He had diabetic retinopathy of Scott IIIb. Before head computerized tomography, the serum BUN was 37 mg/dl, and creatinine was 4.1 mg/dl. Oliguria began immediately after the scanning and confinued for 48 hr. The serum levels of BUN and creatinine rose to 106 and 7.7 mg/dl, respectively. Case 2 was a 49-year-old male who had been diagnosed as having diabetes 15 years before. He showed Scott IIb and IV retinopathy. The BUN and creatinine levels in the serum were 32 and 2.3 mg/dl, respectively. After receiving head computerized tomography, he developed oliguria and remained oliguric for 48 hr. During that period, the serum levels of BUN and creatinin were elevated to 112 and 7.5 mg/dl, respectively. Fortunately, both of these patients recovered from the oliguria without resorting to hemodialysis. The iodine contrast medium routinely used for contrast enhancement in the head computerized tomography was implicated in the acute renal failure of these patients. Only eleven cases have so far been reported in the literature who developed acute renal failure following computerized tomography. In view of the three or four times greater dosis of iodine contrast medium employed in computerized tomography compared to intravenous pyelography, the acute incidence of such complications might be much higher. Among the thirteen cases including the two reported here, as many as eight were diabetic. It is well recongnized that the incidence of acute renal failure after intravenous pyelography is particularly high in cases of diabetic nephropathy.

  18. The operating mode of the two-cascade thermoelectric cooling device providing the minimum failure rate

    Directory of Open Access Journals (Sweden)

    Socheslav D. P.

    2011-04-01

    Full Text Available The model of interrelation of reliability indicators and the basic significant parameters of the two-cascade thermoelectric cooling device (TED with consecutive electric connection of cascades is considered. The relations are received allowing to estimate reliability indicators, namely failure rate at construction two-cascade ТED working in current mode, providing the minimum failure rate in a wide range of temperature drops taking into account thermal loading.Possibility of use of this mode when the prevailing requirement is maintenance of the minimum failure rate and the maximum probability of non-failure operation cascade TED is shown.

  19. Weighted Fuzzy Risk Priority Number Evaluation of Turbine and Compressor Blades Considering Failure Mode Correlations

    Science.gov (United States)

    Gan, Luping; Li, Yan-Feng; Zhu, Shun-Peng; Yang, Yuan-Jian; Huang, Hong-Zhong

    2014-06-01

    Failure mode, effects and criticality analysis (FMECA) and Fault tree analysis (FTA) are powerful tools to evaluate reliability of systems. Although single failure mode issue can be efficiently addressed by traditional FMECA, multiple failure modes and component correlations in complex systems cannot be effectively evaluated. In addition, correlated variables and parameters are often assumed to be precisely known in quantitative analysis. In fact, due to the lack of information, epistemic uncertainty commonly exists in engineering design. To solve these problems, the advantages of FMECA, FTA, fuzzy theory, and Copula theory are integrated into a unified hybrid method called fuzzy probability weighted geometric mean (FPWGM) risk priority number (RPN) method. The epistemic uncertainty of risk variables and parameters are characterized by fuzzy number to obtain fuzzy weighted geometric mean (FWGM) RPN for single failure mode. Multiple failure modes are connected using minimum cut sets (MCS), and Boolean logic is used to combine fuzzy risk priority number (FRPN) of each MCS. Moreover, Copula theory is applied to analyze the correlation of multiple failure modes in order to derive the failure probabilities of each MCS. Compared to the case where dependency among multiple failure modes is not considered, the Copula modeling approach eliminates the error of reliability analysis. Furthermore, for purpose of quantitative analysis, probabilities importance weight from failure probabilities are assigned to FWGM RPN to reassess the risk priority, which generalize the definition of probability weight and FRPN, resulting in a more accurate estimation than that of the traditional models. Finally, a basic fatigue analysis case drawn from turbine and compressor blades in aeroengine is used to demonstrate the effectiveness and robustness of the presented method. The result provides some important insights on fatigue reliability analysis and risk priority assessment of structural

  20. 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

  1. Concepts for measuring maintenance performance and methods for analysing competing failure modes

    DEFF Research Database (Denmark)

    Cooke, R.; Paulsen, J.L.

    1997-01-01

    competing failure modes. This article examines ways to assess maintenance performance without introducing statistical assumptions, then introduces a plausible statistical model for describing the interaction of preventive and corrective maintenance, and finally illustrates these with examples from...

  2. 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

  3. Life Prediction and Classification of Failure Modes in Solid State Luminaires Using Bayesian Probabilistic Models

    Energy Technology Data Exchange (ETDEWEB)

    Lall, Pradeep; Wei, Junchao; Sakalaukus, Peter

    2014-05-27

    A new method has been developed for assessment of the onset of degradation in solid state luminaires to classify failure mechanisms by using metrics beyond lumen degradation that are currently used for identification of failure. Luminous Flux output, Correlated Color Temperature Data on Philips LED Lamps has been gathered under 85°C/85%RH till lamp failure. The acquired data has been used in conjunction with Bayesian Probabilistic Models to identify luminaires with onset of degradation much prior to failure through identification of decision boundaries between lamps with accrued damage and lamps beyond the failure threshold in the feature space. In addition luminaires with different failure modes have been classified separately from healthy pristine luminaires. It is expected that, the new test technique will allow the development of failure distributions without testing till L70 life for the manifestation of failure.

  4. TARDEC FMEA TRAINING: Understanding and Evaluating Failure Mode and Effects Analyses (FMEA)

    Science.gov (United States)

    2012-06-07

    Unclassified TARDEC FMEA TRAINING: Understanding and Evaluating Failure Mode and Effects Analyses ( FMEA ) TARDEC Systems Engineering Risk...JUN 2012 2. REPORT TYPE Briefing Charts 3. DATES COVERED 01-05-2012 to 31-05-2012 4. TITLE AND SUBTITLE TARDEC FMEA TRAINING: Understanding...and Evaluating Failure Mode and Effects Analyses ( FMEA ) 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Kadry Rizk

  5. 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...

  6. 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.

  7. A map of competing buckling-driven failure modes of substrate-supported thin brittle films

    Energy Technology Data Exchange (ETDEWEB)

    Jia, Zheng [Department of Mechanical Engineering and Maryland NanoCenter, University of Maryland, College Park, MD 20742 (United States); Peng, Cheng [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005 (United States); Lou, Jun, E-mail: jlou@rice.edu [Department of Mechanical Engineering and Materials Science, Rice University, Houston, TX 77005 (United States); Li, Teng, E-mail: lit@umd.edu [Department of Mechanical Engineering and Maryland NanoCenter, University of Maryland, College Park, MD 20742 (United States)

    2012-08-31

    Our in situ experiments of polyimide-supported thin indium tin oxide (ITO) films reveal buckling-driven film cracking in some samples and buckling-driven interfacial delamination in other samples. Although studies of individual buckling-driven failure mode exist, it still remains unclear what governs the competition between these two different failure modes in a given film/substrate structure. Through theoretical analysis and numerical simulations, we delineate a map of competing buckling-driven failure modes of substrate-supported thin brittle films in the parameter space of interfacial adhesion and interfacial imperfection size. Such a map can offer insight on the mechanical durability of functional thin films. For example, interestingly, we show that strongly bonded thin brittle films are more prone to buckling-driven cracking, a more detrimental failure mode for thin brittle ITO transparent conductors widely used in displays and flexible electronics. - Highlights: Black-Right-Pointing-Pointer Map of buckling-driven failure modes of thin brittle films on substrates. Black-Right-Pointing-Pointer We study key parameters that govern buckling-driven failure modes. Black-Right-Pointing-Pointer The map offers insights on optimal design of functional thin films.

  8. 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...

  9. 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...

  10. Failure modes of prestressed CFRP rods in a wedge anchored set-up

    DEFF Research Database (Denmark)

    Bennitz, Anders; Schmidt, Jacob Wittrup; Täljsten, Björn

    2009-01-01

    : soft slip, power slip, cutting of fibres, crushing of rod, bending of fibres, frontal overload and intermediate rupture. In this paper the failure modes are discussed further. The failures are documented with explanatory figures and their backgrounds are found in the theory. Suggestions are given...

  11. 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.

  12. 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.

  13. 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.

  14. A new mixed-mode failure criterion for weak snowpack layers

    Science.gov (United States)

    Reiweger, I.; Gaume, J.; Schweizer, J.

    2015-03-01

    The failure of a weak snow layer is the first in a series of processes involved in dry-snow slab avalanche release. The nature of the initial failure within the weak layer is not yet fully understood but widely debated. The knowledge of the failure criterion is essential for developing avalanche release models and hence for avalanche hazard assessment. Yet different release models assume contradictory criteria as input parameters. We analyzed loading experiments on snow failure performed in a cold laboratory with samples containing a persistent weak snow layer of either faceted crystal, depth hoar, or buried surface hoar. The failure behavior of these layers can be described well with a modified Mohr-Coulomb model accounting for the possible compressive failure of snow. We consequently propose a new mixed-mode shear-compression failure criterion that can be used in avalanche release models.

  15. 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

  16. 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.

  17. Transition among failure modes of the bending system with a stiff film on a soft substrate

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Longchao [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Department of Engineering, The University of Leicester, Leicester LE27GP (United Kingdom); Huang, Yin; Chen, Hang; Feng, Xue, E-mail: fengxue@tsinghua.edu.cn [AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084 (China); Center for Mechanics and Materials, Tsinghua University, Beijing 100084 (China); Fang, Daining [LTCS and College of Engineering, Peking University, Beijing 100871 (China)

    2015-01-12

    Growing interest is being attracted by stretchable and flexible electronics recently due to their attractive characteristics, commercial potentials, and engineering challenges. In comparison with the system on a macroscopic scale, different failure modes are observed in a system with a thin film bonded on an elastomeric substrate. Furthermore, the experimental observations reveal that failure modes occur in turn with the increasing of thickness ratio of the film to substrate. In this paper, theoretical analysis is performed on the failure mechanism in this system with the focus on transitions among these failure modes based on the theory of fracture mechanics. The present theoretical predictions are coincident with related experiment results and can be used to guide the related structural design.

  18. FMEA Based Risk Assessment of Component Failure Modes in Industrial Radiography

    CERN Document Server

    Pandey, Alok; Sonawane, A U; Rawat, Prashant S

    2016-01-01

    Industrial radiography has its inimitable role in non-destructive examinations. Industrial radiography devices, consisting of significantly high activity of the radioisotopes, are operated manually by remotely held control unit. Malfunctioning of these devices may cause potential exposure to the operator and nearby public, and thus should be practiced under a systematic risk control. To ensure the radiation safety, proactive risk assessment should be implemented. Risk assessment in industrial radiography using the Failure Modes & Effect Analysis (FMEA) for the design and operation of industrial radiography exposure devices has been carried out in this study. Total 56 component failure modes were identified and Risk Priority Numbers (RPNs) were assigned by the FMEA expert team, based on the field experience and reported failure data of various components. Results shows all the identified failure modes have RPN in the range of 04 to 216 and most of the higher RPN are due to low detectability and high severi...

  19. Failure mode diagram of rubble pile asteroids: Application to (25143) asteroid Itokawa

    Science.gov (United States)

    Hirabayashi, Masatoshi; Scheeres, Daniel J.

    2016-01-01

    Proposing a diagram which shows the variation in asteroidal failure as a function of a spin period, later called the failure mode diagram, this paper considers the failure modes and conditions of asteroid (25143) Itokawa. This diagram is useful to describe when and where failure occurs in an asteroid. Assuming that Itokawa is homogeneous, we use a plastic finite element code to obtain the diagram for this object. The results show that if the bulk cohesive strength is less than 0.1 Pa, Itokawa experiences compressional failure on the neck surface at the current spin period 12.1 hours. At a spin period shorter than 4.5 hours, tension across the neck causes this asteroid to split into two components. It is also found that if the breakup spin period is longer than 5.2 hours, their motion is bounded. This implies that once Itokawa splits, the components may escape from one another.

  20. Failure pattern and salvage treatment after radical treatment of head and neck cancer

    DEFF Research Database (Denmark)

    Pagh, Anja; Grau, Cai; Overgaard, Jens

    2016-01-01

    Purpose The aim of the study was to test the hypothesis that head and neck cancer (HNC) patients benefit from specialized follow-up (FU), as this strategy ensures timely detection of relapses for successful salvage treatment. This was done by evaluation of the pattern of failure, the temporal...... recordings of recurrent disease in 567 patients with primary tumors of the larynx, pharynx, oral cavity, nasal cavity, paranasal sinuses and salivary glands. A review of medical records was performed in order to update and supplement the database. Results Failures of the 567 patients were primarily in T...... in terms of a complete response. Permanent tumor control was observed in 128 patients (23%) after one or two salvage attempts. The highest salvage rate was recorded in patients with primary glottic carcinoma (41%) and the lowest among hypopharyngeal cancers (2%). Asymptomatic recurrence was recorded in 12...

  1. 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.

  2. [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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. Specific Energy as an Index to Identify the Critical Failure Mode Transition Depth in Rock Cutting

    Science.gov (United States)

    He, Xianqun; Xu, Chaoshui

    2016-04-01

    Rock cutting typically involves driving a rigid cutter across the rock surface at certain depth of cut and is used to remove rock material in various engineering applications. It has been established that there exist two distinct failure modes in rock cutting, i.e. ductile mode and brittle mode. The ductile mode takes precedence when the cut is shallow and the increase in the depth of cut leads to rock failure gradually shifted to brittle-dominant mode. The threshold depth or the critical transition depth, at which rock failure under cutting changes from the ductile to the brittle mode, is associated with not only the rock properties but also the cutting operational parameters and the understanding of this threshold is important to optimise the tool design and operational parameters. In this study, a new method termed the specific cutting energy transition model is proposed from an energy perspective which is demonstrated to be much more effective in identifying the critical transition depth compared with existing approaches. In the ductile failure cutting mode, the specific cutting energy is found to be independent of the depth of cut; but in the brittle failure cutting mode, the specific cutting energy is found to be dependent on the depth of cut following a power-law relationship. The critical transition depth is identified as the intersection point between these two relationships. Experimental tests on two types of rocks with different combinations of cutting velocity, depth of cut and back rake angle are conducted and the application of the proposed model on these cutting datasets has demonstrated that the model can provide a very effective tool to analyse the cutting mechanism and to identify the critical transition depth.

  8. 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

  9. Research on Failure Modes and Key Parameters of Corrugated Steel Shear Walls

    Directory of Open Access Journals (Sweden)

    Cao Qiang

    2016-01-01

    Full Text Available The corrugated steel plate shear wall is an effective and economical lateral load resisting system. And the thin steel plate is easy to buckle. And it is necessary to use much more thickness or ribs to prevent the buckle at out of plane direction, which is not economical or complicated to construct. A number of corrugated shear walls are analyzed by nonlinear static pushover analysis method. And failure modes, buckling, the ultimate capacity, and shear force-drift curves are studied. The results showed that the corrugated steel plate can be designed according to the failure modes, in order to have a desirable failure mode that the corrugated steel plate yield before buckling.

  10. Study of electrical breakdown and secondary pull-in failure modes for NEM relays

    Science.gov (United States)

    Ramezani, M.; Severi, S.; Tilmans, H. A. C.; De Meyer, K.

    2017-01-01

    In this work, two common failure modes of nano-electro-mechanical (NEM) relays: (1) electrical breakdown and (2) stiction due to secondary pull-in were analyzed. These effects are dominant when dimensions of the device are scaled to the sub-micrometer scale. Like MEMS devices, design adjustments, such as introduction of dimples, cannot provide a solution. The geometrical parameters and working environment drive directly the occurrence of these failure modes. The beam length is the key parameter in driving the electrical breakdown while the distance of the gate to the drain, the beam thickness, and the actuation gap set the limits for secondary pull-in voltage. The analysis shows that these failure modes could be mitigated and a physical parameters design space could be identified to achieve NEM devices for high speed operation.

  11. The Influence of Pier Stiffness Ratio on the Failure Modes of Masonry Structures

    Directory of Open Access Journals (Sweden)

    Yanru Wang

    2015-01-01

    Full Text Available Masonry structure is the main form of Chinese urban and rural housing construction structure. And heavy casualties and huge economic losses are caused by the damages of masonry structures in the previous destructive earthquake. So the failure modes of masonry structures are analyzed in the paper. ABAQUS software was used; and the Xuankou High School Student Dormitory of masonry structure in Yingxiu town, severely damaged under the Wenchuan earthquake, was taken for example. The influence of the stiffness ratio of pier between windows and spandrel on the failure modes of masonry structures is discussed. The results show that the failure modes in the earthquake could be changed by controlling the stiffness ratio. Suitable stiffness ratio helps proper design of masonry structures.

  12. Failure mode transition in AHSS resistance spot welds. Part II: Experimental investigation and model validation

    Energy Technology Data Exchange (ETDEWEB)

    Pouranvari, M., E-mail: mpouranvari@yahoo.com [Young Researchers Club, Dezful Branch, Islamic Azad University, Dezful (Iran, Islamic Republic of); Marashi, S.P.H.; Safanama, D.S. [Mining and Metallurgical Engineering Department, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of)

    2011-11-15

    Highlights: {yields} Interfacial to pullout failure mode transition for AHSS RSWs is experimentally studied. {yields} Relation between failure mode and metallurgical factors of AHSS RSW is studied. {yields} HAZ softening reduces FZ size require to ensure pullout failure. {yields} HAZ softening enhances energy absorption capability of AHSS RSW. {yields} Good agreement between model prediction and experimental results was observed. - Abstract: The objective of this paper is to investigate and analyze the transition criteria from interfacial to pullout failure mode in AHSS resistance spot welds during the tensile-shear test by the use of both experimental and analytical approaches. Spot welds were made on three dual phase steel grades including DP600, DP780 and DP980. A low strength drawing quality special killed (DQSK) steel and AISI 304 austenitic stainless steel were also tested as a baseline for comparison. The microstructure and mechanical strength of the welds were characterized using metallographic techniques and the tensile-shear testing. Correlations among critical fusion zone (FZ) size required to ensure the pullout failure mode, weld microstructure and weld hardness characteristics were developed. It was found that critical FZ size increases in the order of DQSK, DP600, DP980, DP780 and AISI304. No direct relationship was found between the tensile strength of the base metal and the critical FZ size. It was concluded that low hardness ratio of FZ to pullout failure location and high susceptibility to form shrinkage voids are two primary reasons for high tendency of AHSS to fail in interfacial mode. HAZ softening can improve RSW mechanical performance in terms of load bearing capacity and energy absorption capability. This phenomenon promotes PF mode at smaller FZ sizes. This fact can explain smaller critical FZ size measured for DP980 in comparison with DP780. The results obtained from the model were compared to the experimental results and the literature

  13. 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.

  14. 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.

  15. 一种FIFO器件的失效模式分析%A FIFO Device Failure Mode Analysis

    Institute of Scientific and Technical Information of China (English)

    朱野; 李华旺; 戴娅; 赵毅

    2012-01-01

    异步FIFO常应用于在异步时钟域之间进行数据传输。本文根据应用过程中数据帧头重复首字节的异常现象,对FIFO器件M67024的一种失效模式进行分析和说明。进而分析FIFO因设计原理而存在的共性使用要求,并提出针对该类型FIFO失效模式,电路设计人员应当注意的设计规则。%Asynchronous FIFO often used in asynchronous clock domain data transfer.According to the frame repeat failure mode duringa data communication system development, this article description and analysis head FIFO device M67204' s anomaly behavior. Further analysis of FIFO for the design principle and the common application requirements, attentmn to according to type of FIFO failure mode, what design rules the circuit designer should pay

  16. 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.

  17. 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.

  18. Effects of soil-engineering properties on the failure mode of shallow landslides

    Science.gov (United States)

    McKenna, Jonathan Peter; Santi, Paul Michael; Amblard, Xavier; Negri, Jacquelyn

    2012-01-01

    Some landslides mobilize into flows, while others slide and deposit material immediately down slope. An index based on initial dry density and fine-grained content of soil predicted failure mode of 96 landslide initiation sites in Oregon and Colorado with 79% accuracy. These material properties can be used to identify potential sources for debris flows and for slides. Field data suggest that loose soils can evolve from dense soils that dilate upon shearing. The method presented herein to predict failure mode is most applicable for shallow (depth 8), with few to moderate fines (fine-grained content <18%), and with liquid limits <40.

  19. Global Failure Modes in Composite Structures for High Altitudes

    Science.gov (United States)

    Knauss, W. G.

    2004-01-01

    This report summarizes the accomplishments under the referenced grant. The work described was started under the guidance and supervision of the late Dr. James Stames as the technical contact. It was aimed at investigating the development of analysis tools to deal with the problem of rupture in reinforced structural skin of future composites-based aircraft. It was of particular interest to assess methods by which failure features reminiscent of cracks in metallic structures would develop and propagate in fiber reinforced structures in interaction with the reinforcing frame. To eventually achieve that goal it was necessary to first understand the stress or strain distribution at the front of such features so that interactions between such features and reinforcing agents could be assessed computationally. Thus the major emphasis here was on the assessment of damage front and methods on how to assess or characterize it. During the conduct of this research program Dr. Stames changed to a different NASA- internal assignment, which divorced him of the direct supervision of this grant. A student who was approximately % into the completion of his Ph.D. research needed to finish this work, and NASA funds were made available under Dr. Damodar Ambur, the successor Branch Manager for Dr. James Starnes, for the completion of this work. The current grant was the thus a new and fmal support increment for completion of the started research. Final reports for previous funding have been completed and submitted. Because of the interconnection of this last phase of the investigation with previous work it is deemed useful to make the Ph.D. thesis by Luis Gonzales the body of this report.

  20. Interface failure modes explain non-monotonic size-dependent mechanical properties in bioinspired nanolaminates

    Science.gov (United States)

    Song, Z. Q.; Ni, Y.; Peng, L. M.; Liang, H. Y.; He, L. H.

    2016-03-01

    Bioinspired discontinuous nanolaminate design becomes an efficient way to mitigate the strength-ductility tradeoff in brittle materials via arresting the crack at the interface followed by controllable interface failure. The analytical solution and numerical simulation based on the nonlinear shear-lag model indicates that propagation of the interface failure can be unstable or stable when the interfacial shear stress between laminae is uniform or highly localized, respectively. A dimensionless key parameter defined by the ratio of two characteristic lengths governs the transition between the two interface-failure modes, which can explain the non-monotonic size-dependent mechanical properties observed in various laminate composites.

  1. Risk assessment of failure modes of gas diffuser liner of V94.2 siemens gas turbine by FMEA method

    Science.gov (United States)

    Mirzaei Rafsanjani, H.; Rezaei Nasab, A.

    2012-05-01

    Failure of welding connection of gas diffuser liner and exhaust casing is one of the failure modes of V94.2 gas turbines which are happened in some power plants. This defect is one of the uncertainties of customers when they want to accept the final commissioning of this product. According to this, the risk priority of this failure evaluated by failure modes and effect analysis (FMEA) method to find out whether this failure is catastrophic for turbine performance and is harmful for humans. By using history of 110 gas turbines of this model which are used in some power plants, the severity number, occurrence number and detection number of failure determined and consequently the Risk Priority Number (RPN) of failure determined. Finally, critically matrix of potential failures is created and illustrated that failure modes are located in safe zone.

  2. Failure Modes for Single-Layer Reticulated Domes Under Impact Loads

    Institute of Scientific and Technical Information of China (English)

    FAN Feng; WANG Duozhi; ZHI Xudong; SHEN Shizhao

    2008-01-01

    The paper presents the theory of Hamilton variation principle which is the current method for impact problem,central difference method which is efficient solution of finite element (FE)method for impact problem and adapts to solve non-linear dynamic problem.And it introduces the ANSYS/LS-DYNA which is the popular FE software for impact problem both at home and abroad.Then it gives solutions for one simple model by analytical method and ANSYS/LS-DYNA respectively to validate function of software,and they are consistent.Afterward,it gives model of singlelayer Kiewitt reticulated dome with a span of 60 m,and the cylinder impactor,and introduces the contact interface arithmetic,especially the material model of steel (piecewise linear plasticity model) which takes stain rate into account and makes steel failure stress higher under impact loads.The vertical displacement,stress in main members,and the plastic deformation for dome under impact loads were obtained.Then four failure modes (no failure,moderate failure,global failure and slight failure) were summarized according to the rules of dynamic response.And the characteristics of dynamic response for each failure mode were shown.

  3. Finite element modelling of woven composite failure modes at the mesoscopic scale: deterministic versus stochastic approaches

    Science.gov (United States)

    Roirand, Q.; Missoum-Benziane, D.; Thionnet, A.; Laiarinandrasana, L.

    2017-09-01

    Textile composites are composed of 3D complex architecture. To assess the durability of such engineering structures, the failure mechanisms must be highlighted. Examinations of the degradation have been carried out thanks to tomography. The present work addresses a numerical damage model dedicated to the simulation of the crack initiation and propagation at the scale of the warp yarns. For the 3D woven composites under study, loadings in tension and combined tension and bending were considered. Based on an erosion procedure of broken elements, the failure mechanisms have been modelled on 3D periodic cells by finite element calculations. The breakage of one element was determined using a failure criterion at the mesoscopic scale based on the yarn stress at failure. The results were found to be in good agreement with the experimental data for the two kinds of macroscopic loadings. The deterministic approach assumed a homogeneously distributed stress at failure all over the integration points in the meshes of woven composites. A stochastic approach was applied to a simple representative elementary periodic cell. The distribution of the Weibull stress at failure was assigned to the integration points using a Monte Carlo simulation. It was shown that this stochastic approach allowed more realistic failure simulations avoiding the idealised symmetry due to the deterministic modelling. In particular, the stochastic simulations performed have shown several variations of the stress as well as strain at failure and the failure modes of the yarn.

  4. Modeling of failure mode in knee ligaments depending on the strain rate

    Directory of Open Access Journals (Sweden)

    Hyman William

    2002-01-01

    Full Text Available Abstract Background The failure mechanism of the knee ligament (bone-ligament-bone complex at different strain rates is an important subject in the biomechanics of the knee. This study reviews and summarizes the literature describing ligament injury as a function of stain rate, which has been published during the last 30 years. Methods Three modes of injury are presented as a function of strain rate, and they are used to analyze the published cases. The number of avulsions is larger than that of ligament tearing in mode I. There is no significant difference between the number of avulsions and ligament tearing in mode II. Ligament tearing happens more frequently than avulsion in mode III. Results When the strain rate increases, the order of mode is mode I, II, III, I, and II. Analytical models of ligament behavior as a function of strain rate are also presented and used to provide an integrated framework for describing all of the failure regimes. In addition, this study showed the failure mechanisms with different specimens, ages, and strain rates. Conclusion There have been several a numbers of studies of ligament failure under various conditions including widely varying strain rates. One issue in these studies is whether ligament failure occurs mid-ligament or at the bone attachment point, with assertions that this is a function of the strain rate. However, over the range of strain rates and other conditions reported, there has appeared to be discrepancies in the conclusions on the effect of strain rate. The analysis and model presented here provides a unifying assessment of the previous disparities, emphasizing the differential effect of strain rate on the relative strengths of the ligament and the attachment.

  5. 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

  6. 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.

  7. Structural integrity and potential failure modes of hanford high-level waste tanks

    Energy Technology Data Exchange (ETDEWEB)

    Han, F.C.

    1996-09-30

    Structural Integrity of the Hanford High-Level Waste Tanks were evaluated based on the existing Design and Analysis Documents. All tank structures were found adequate for the normal operating and seismic loads. Potential failure modes of the tanks were assessed by engineering interpretation and extrapolation of the existing engineering documents.

  8. 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

  9. 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

  10. 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.

  11. 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.

  12. 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.

  13. Simulation and design of fuzzy sliding-mode controller for ship heading-tracking

    Science.gov (United States)

    Yuan, Lei; Wu, Hansong

    2011-03-01

    In considering the characteristic of a rudder, the maneuvers of a ship were described by an unmatched uncertain nonlinear mathematic model with unknown virtual control coefficient and parameter uncertainties. In order to solve the uncertainties in the ship heading control, specifically the controller singular and paramount re-estimation problem, a new multiple sliding-mode adaptive fuzzy control algorithm was proposed by combining Nussbaum gain technology, the approximation property of fuzzy logic systems, and a multiple sliding-mode control algorithm. Based on the Lyapunov function, it was proven in theory that the controller made all signals in the nonlinear system of unmatched uncertain ship motion uniformly bounded, with tracking errors converging to zero. Simulation results show that the demonstrated controller design can track a desired course fast and accurately. It also exhibits strong robustness peculiarity in relation to system uncertainties and disturbances.

  14. 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”,

  15. Mixed-mode shear-compression failure criterion for weak snowpack layers

    Science.gov (United States)

    Reiweger, Ingrid; Gaume, Johan; Schweizer, Jürg

    2015-04-01

    The failure of a weak snow layer below a cohesive slab is a prerequisite for the release of a dry-snow snow slab avalanche. Once an initial failure in the weak layer reaches its critical size to become self-propagating, the slab will release as an avalanche - provided the slope is steep enough. However, the nature of the initial failure within the weak layer is still unknown - but strongly debated among avalanche researchers. Moreover, different avalanche release models assume contradictory failure criteria as input parameters. We analysed a unique data set stemming from laboratory experiments on snow failure with samples containing a weak snow layer of either depth hoar or buried surface hoar. Depth and surface hoar layers are the most relevant weak layers for avalanche release. The failure behaviour of these types of weak layers can well be described with a modified Mohr-Coulomb model. We therefore propose a mixed-mode failure criterion to be used in avalanche release models.

  16. 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.

  17. Change of the mode of failure by interface friction and width-to-height ratio of coal specimens

    Directory of Open Access Journals (Sweden)

    Gamal Rashed

    2015-06-01

    Full Text Available Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings. Previous studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height (W/H ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed.

  18. Change of the mode of failure by interface friction and width-to-height ratio of coal specimens

    Institute of Scientific and Technical Information of China (English)

    Gamal Rashed; Syd S. Peng

    2015-01-01

    abstract Bumps in coal mines have been recognized as a major hazard for many years. These sudden and violent failures around mine openings have compromised safety, ventilation and access to mine workings. Previous studies showed that the violence of coal specimen failure depends on both the interface friction and width-to-height (W/H) ratio of coal specimen. The mode of failure for a uniaxially loaded coal specimen or a coal pillar is a combination of both shear failure along the interface and compressive failure in the coal. The shear failure along the interface triggered the compressive failure in coal. The compressive failure of a coal specimen or a coal pillar can be controlled by changing its W/H ratio. As the W/H ratio increases, the ultimate strength increases. Hence, with a proper combination of interface friction and the W/H ratio of pillar or coal specimen, the mode of failure will change from sudden violent failure which is brittle failure to non-violent failure which is ductile failure. The main objective of this paper is to determine at what W/H ratio and interface friction the mode of failure changes from violent to non-violent. In this research, coal specimens of W/H ratio ranging from 1 to 10 were uniaxially tested under two interface frictions of 0.1 and 0.25, and the results are presented and discussed.

  19. Numerical simulation study of the failure evolution process and failure mode of surrounding rock in deep soft rock roadways

    Institute of Scientific and Technical Information of China (English)

    Meng Qingbin; Han Lijun; Xiao Yu; Li Hao; Wen Shengyong; Zhang Jian

    2016-01-01

    Based on the safety coefficient method, which assigns rock failure criteria to calculate the rock mass unit, the safety coefficient contour of surrounding rock is plotted to judge the distribution form of the frac-tured zone in the roadway. This will provide the basis numerical simulation to calculate the surrounding rock fractured zone in a roadway. Using the single factor and multi-factor orthogonal test method, the evolution law of roadway surrounding rock displacements, plastic zone and stress distribution under different conditions is studied. It reveals the roadway surrounding rock burst evolution process, and obtains five kinds of failure modes in deep soft rock roadway. Using the fuzzy mathematics clustering analysis method, the deep soft surrounding rock failure model in Zhujixi mine can be classified and pat-terns recognized. Compared to the identification results and the results detected by geological radar of surrounding rock loose circle, the reliability of the results of the pattern recognition is verified and lays the foundations for the support design of deep soft rock roadways.

  20. Rapid repair of severely earthquake-damaged bridge piers with flexural-shear failure mode

    Science.gov (United States)

    Sun, Zhiguo; Wang, Dongsheng; Du, Xiuli; Si, Bingjun

    2011-12-01

    An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural-shear failure mode. Six circular pier specimens were first tested to severe damage in flexural-shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers (CFRP). After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural-shear failure to ductile flexural failure. Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.5 times more FRP sheets is provided.

  1. Data Collection Plan to Populate the Light Water Reactor Sustainability Failure Mode Degradation Library

    Energy Technology Data Exchange (ETDEWEB)

    Magdy S. Tawfik; Binh T. Pham; Vivek Agarwal; Nancy J. Lybeck

    2011-09-01

    Interest in implementing advanced Prognostic Health Management (PHM) systems in commercial nuclear power plants (NPPs) has increased rapidly in recent years, with an overarching goal of implementing of improving the safety, reliability, and economics/profitability of the aging nuclear fleet and extending their service life in the most cost-effective manner. The PHM system utilizes prognostic tools to estimate the remaining useful life (RUL) of a component or system of components based on current and predicted operating conditions. An effective implementation of the PHM system will anticipate and identify unique age-dependent degradation modes to provide early warning of emerging problems. Selection of the components and structures to be monitored is a crucial step for successful PHM implementation in NPPs. A selection framework is recommended for risk significant components (both safety-related and non-safety related) based on the Fussell-Vesely (F-V) Importance Measure and the Risk Achievement Worth (RAW) measure. For the selected components, a failure mode degradation library will be developed consisting of data corresponding to different failure/degradation modes. In lieu of constructing an expensive scaled test facility, several data sources are identified for populating the failure mode degradation library, including various national laboratories, universities, agencies, and industries.

  2. Periodic imperfect preventive maintenance with two categories of competing failure modes

    Energy Technology Data Exchange (ETDEWEB)

    Zequeira, R.I. [ISTIT FRE CNRS 2732-Equipe LM2S, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France)]. E-mail: romulo.zequeira@utt.fr; Berenguer, C. [ISTIT FRE CNRS 2732-Equipe LM2S, Universite de Technologie de Troyes, 12 rue Marie Curie, BP 2060, 10010 Troyes (France)]. E-mail: christophe.berenguer@utt.fr

    2006-04-15

    A maintenance policy is studied for a system with two types of failure modes: maintainable and non-maintainable. The quality of maintenance actions is modelled by its effect on the system failure rate. Preventive maintenance actions restore the system to a condition between as good as new and as bad as immediately before the maintenance action. The model presented permits to study the equipment condition improvement (improvement factor) as a function of the time of the preventive maintenance action. The determination of the maintenance policy, which minimizes the cost rate for an infinite time span, is examined. Conditions are given under which a unique optimal policy exists.

  3. 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.

  4. Sliding Mode Control of the X-33 with an Engine Failure

    Science.gov (United States)

    Shtessel, Yuri B.; Hall, Charles E.

    2000-01-01

    Ascent flight control of the X-3 is performed using two XRS-2200 linear aerospike engines. in addition to aerosurfaces. The baseline control algorithms are PID with gain scheduling. Flight control using an innovative method. Sliding Mode Control. is presented for nominal and engine failed modes of flight. An easy to implement, robust controller. requiring no reconfiguration or gain scheduling is demonstrated through high fidelity flight simulations. The proposed sliding mode controller utilizes a two-loop structure and provides robust. de-coupled tracking of both orientation angle command profiles and angular rate command profiles in the presence of engine failure, bounded external disturbances (wind gusts) and uncertain matrix of inertia. Sliding mode control causes the angular rate and orientation angle tracking error dynamics to be constrained to linear, de-coupled, homogeneous, and vector valued differential equations with desired eigenvalues. Conditions that restrict engine failures to robustness domain of the sliding mode controller are derived. Overall stability of a two-loop flight control system is assessed. Simulation results show that the designed controller provides robust, accurate, de-coupled tracking of the orientation angle command profiles in the presence of external disturbances and vehicle inertia uncertainties, as well as the single engine failed case. The designed robust controller will significantly reduce the time and cost associated with flying new trajectory profiles or orbits, with new payloads, and with modified vehicles

  5. Failure mode and bending moment of canine pancarpal arthrodesis constructs stabilized with two different implant systems.

    Science.gov (United States)

    Wininger, Fred A; Kapatkin, Amy S; Radin, Alex; Shofer, Frances S; Smith, Gail K

    2007-12-01

    To compare failure mode and bending moment of a canine pancarpal arthrodesis construct using either a 2.7 mm/3.5 mm hybrid dynamic compression plate (HDCP) or a 3.5 mm dynamic compression plate (DCP). Paired in vitro biomechanical testing of canine pancarpal arthrodesis constructs stabilized with either a 2.7/3.5 HDCP or 3.5 DCP. Paired cadaveric canine antebrachii (n=5). Pancarpal arthrodesis constructs were loaded to failure (point of maximum load) in 4-point bending using a materials-testing machine. Using this point of failure, bending moments were calculated from system variables for each construct and the 2 plating systems compared using a paired t-test. To examine the relationship between metacarpal diameter and screw diameter failure loads, linear regression was used and Pearson' correlation coefficient was calculated. Significance was set at Pbending strength. There was a significant linear correlation r=0.74 (P-slope=.014) and 0.8 (P-slope=.006) between metacarpal diameter and failure loads for the HDCP and 3.5 DCP, respectively. There was a small but significant difference between bending moment at failure between 2.7/3.5 HDCP and 3.5 DCP constructs; however, the difference may not be clinically evident in all patients. The 2.7/3.5 HDCP has physical and mechanical properties making it a more desirable plate for pancarpal arthrodesis.

  6. A structured analysis of in vitro failure loads and failure modes of fiber, metal, and ceramic post-and-core systems.

    NARCIS (Netherlands)

    Fokkinga, W.A.; Kreulen, C.M.; Vallittu, P.K.; Creugers, N.H.J.

    2004-01-01

    PURPOSE: This study sought to aggregate literature data on in vitro failure loads and failure modes of prefabricated fiber-reinforced composite (FRC) post systems and to compare them to those of prefabricated metal, custom-cast, and ceramic post systems. MATERIALS AND METHODS: The literature was sea

  7. 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.

  8. 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.

  9. Characteristics of Welding Crack Defects and Failure Mode in Resistance Spot Welding of DP780 Steel

    Institute of Scientific and Technical Information of China (English)

    Xiao-pei WANG; Yong-qiang ZHANG; Jian-bin JU; Jian-qiang ZHANG; Jian-wei YANG

    2016-01-01

    The mechanical properties of welded joints in resistance spot welding of DP780 steel were tested,and three dif-ferent types of welding cracks in welded joints were investigated by optical microscopy,scanning electron microscopy and electron back-scattered diffraction.Finally,the failure mode of the welded joints in shear tensile test was dis-cussed.It is found the shear tensile strength of welded joints can be greatly improved by adding preheating current or tempering current.The surface crack in welded joint is intergranular fracture,while the inner crack in welded joint is transgranular fracture,and the surface crack on the edge of the electrode imprint can be improved by adding prehea-ting current or tempering current.The traditional failure mode criterion advised by American Welding Society is no longer suitable for DP780 spot welds and the critical nugget size suggested by Pouranvari is overestimated.

  10. Diagnostic assessment of search controls and failure modes in many-objective evolutionary optimization.

    Science.gov (United States)

    Hadka, David; Reed, Patrick

    2012-01-01

    The growing popularity of multiobjective evolutionary algorithms (MOEAs) for solving many-objective problems warrants the careful investigation of their search controls and failure modes. This study contributes a new diagnostic assessment framework for rigorously evaluating the effectiveness, reliability, efficiency, and controllability of MOEAs as well as identifying their search controls and failure modes. The framework is demonstrated using the recently introduced Borg MOEA, [Formula: see text]-NSGA-II, [Formula: see text]-MOEA, IBEA, OMOPSO, GDE3, MOEA/D, SPEA2, and NSGA-II on 33 instances of 18 test problems from the DTLZ, WFG, and CEC 2009 test suites. The diagnostic framework exploits Sobol's variance decomposition to provide guidance on the algorithms' non-separable, multi-parameter controls when performing a many-objective search. This study represents one of the most comprehensive empirical assessments of MOEAs ever completed.

  11. Head-on collision of the second mode internal solitary waves

    Science.gov (United States)

    Terletska, Kateryna; Maderich, Vladimir; Jung, Kyung Tae

    2017-04-01

    Second mode internal waves are widespread in offshore areas, and they frequently follow the first mode internal waves on the oceanic shelf. Large amplitude internal solitary waves (ISW) of second mode containing trapped cores associated with closed streamlines can also transport plankton and nutrients. An interaction of ISWs with trapped cores takes place in a specific manner. It motivated us to carry out a computational study of head-on collision of ISWs of second mode propagating in a laboratory-scale numerical tank using the nonhydrostatic 3D numerical model based on the Navier-Stokes equations for a continuously stratified fluid. Three main classes of ISW of second mode propagating in the pycnocline layer of thickness h between homogeneous deep layers can be identified: (i) the weakly nonlinear waves; (ii) the stable strongly nonlinear waves with trapped cores; and (iii) the shear unstable strongly nonlinear waves (Maderich et al., 2015). Four interaction regimes for symmetric collision were separated from simulation results using this classification: (A) an almost elastic interaction of the weakly nonlinear waves; (B) a non-elastic interaction of waves with trapped cores when ISW amplitudes were close to critical non-dimensional amplitude a/h; (C) an almost elastic interaction of stable strongly nonlinear waves with trapped cores; (D) non-elastic interaction of the unstable strongly nonlinear waves. The unexpected result of simulation was that relative loss of energy due to the collision was maximal for regime B. New regime appeared when ISW of different amplitudes belonged to class (ii) collide. In result of interaction the exchange of mass between ISW occurred: the trapped core of smaller wave was entrained by core of larger ISW without mixing forming a new ISW of larger amplitude whereas in smaller ISW core of smaller wave totally substituted by fluid from larger wave. Overall, the wave characteristics induced by head-on collision agree well with the

  12. 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.

  13. True Triaxial Strength and Failure Modes of Cubic Rock Specimens with Unloading the Minor Principal Stress

    Science.gov (United States)

    Li, Xibing; Du, Kun; Li, Diyuan

    2015-11-01

    True triaxial tests have been carried out on granite, sandstone and cement mortar using cubic specimens with the process of unloading the minor principal stress. The strengths and failure modes of the three rock materials are studied in the processes of unloading σ 3 and loading σ 1 by the newly developed true triaxial test system under different σ 2, aiming to study the mechanical responses of the rock in underground excavation at depth. It shows that the rock strength increases with the raising of the intermediate principal stress σ 2 when σ 3 is unloaded to zero. The true triaxial strength criterion by the power-law relationship can be used to fit the testing data. The "best-fitting" material parameters A and n ( A > 1.4 and n < 1.0) are almost located in the same range as expected by Al-Ajmi and Zimmerman (Int J Rock Mech Min Sci 563 42(3):431-439, 2005). It indicates that the end effect caused by the height-to-width ratio of the cubic specimens will not significantly affect the testing results under true triaxial tests. Both the strength and failure modes of cubic rock specimens under true triaxial unloading condition are affected by the intermediate principal stress. When σ 2 increases to a critical value for the strong and hard rocks (R4, R5 and R6), the rock failure mode may change from shear to slabbing. However, for medium strong and weak rocks (R3 and R2), even with a relatively high intermediate principal stress, they tend to fail in shear after a large amount of plastic deformation. The maximum extension strain criterion Stacey (Int J Rock Mech Min Sci Geomech Abstr 651 18(6):469-474, 1981) can be used to explain the change of failure mode from shear to slabbing for strong and hard rocks under true triaxial unloading test condition.

  14. Lunar Module ECS (Environmental Control System) - Design Considerations and Failure Modes. Part 1

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    Design considerations and failure modes for the Lunar Module (LM) Environmental Control System (ECS) are described. An overview of the the oxygen supply and cabin pressurization, atmosphere revitalization, water management and heat transport systems are provided. Design considerations including reliability, flight instrumentation, modularization and the change to the use of batteries instead of fuel cells are discussed. A summary is provided for the LM ECS general testing regime.

  15. Memories and NASA Spacecraft: A Description of Memories, Radiation Failure Modes, and System Design Considerations

    Science.gov (United States)

    LaBel, Kenneth A.; Ladbury, Ray; Oldhamm, Timothy

    2010-01-01

    As NASA has evolved it's usage of spaceflight computing, memory applications have followed as well. In this slide presentation, the history of NASA's memories from magnetic core and tape recorders to current semiconductor approaches is discussed. There is a brief description of current functional memory usage in NASA space systems followed by a description of potential radiation-induced failure modes along with considerations for reliable system design.

  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. Predicting the creep life and failure mode of low-alloy steel weldments

    Energy Technology Data Exchange (ETDEWEB)

    Brear, J.M.; Middleton, C.J.; Aplin, P.F. [ERA Technology Ltd., Leatherhead (United Kingdom)

    1998-12-31

    This presentation reviews and consolidates experience gained through a number of research projects and practical plant assessments in predicting both the life and the likely failure mode and location in low alloy steel weldments. The approach adopted begins with the recognition that the relative strength difference between the microstructural regions is a key factor controlling both life and failure location. Practical methods based on hardness measurement and adaptable to differing weld geometries are presented and evidence for correlations between hardness ratio, damage accumulation and strain development is discussed. Predictor diagrams relating weld life and failure location to the service conditions and the hardness of the individual microstructural constituents are suggested and comments are given on the implications for identifying the circumstances in which Type IV cracking is to be expected. (orig.) 6 refs.

  19. Cardiac and Hemodynamic Benefits: Mode of Action of Ivabradine in Heart Failure.

    Science.gov (United States)

    Pereira-Barretto, Antonio Carlos

    2015-10-01

    Heart failure has seen a number of therapeutic advances in recent years. Despite this, heart failure is still related to increasing rates of morbidity, repeated hospitalizations, and mortality. Ivabradine is a recent treatment option for heart failure. It has a mode of action that includes reduction in heart rate, and leads to improvement in outcomes related to heart failure mortality and morbidity, as demonstrated by the results of the SHIFT trial in patients with systolic heart failure, functional classes II and III on the New York Heart Association classification, and left ventricular ejection fraction ≤ 35%. These results are intriguing since many heart failure drugs reduce heart rate without such benefits, or with quite different effects, making it more difficult to understand the novelty of ivabradine in this setting. Many of the drugs used in heart failure modify heart rate, but most have other pathophysiological effects beyond their chronotropic action, which affect their efficacy in preventing morbidity and mortality outcomes. For instance, heart rate reduction at rest or exercise with ivabradine prolongs diastolic perfusion time, improves coronary blood flow, and increases exercise capacity. Another major difference is the increase in stroke volume observed with ivabradine, which may underlie its beneficial cardiac effects. Finally, there is mounting evidence from both preclinical and clinical studies that ivabradine has an anti-remodeling effect, improving left ventricular structures and functions. All together, these mechanisms have a positive impact on the prognosis of ivabradine-treated patients with heart failure, making a compelling argument for use of ivabradine in combination with other treatments.

  20. 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.

  1. Precursory changes in seismic velocity for the spectrum of earthquake failure modes

    Science.gov (United States)

    Scuderi, M. M.; Marone, C.; Tinti, E.; di Stefano, G.; Collettini, C.

    2016-09-01

    Temporal changes in seismic velocity during the earthquake cycle have the potential to illuminate physical processes associated with fault weakening and connections between the range of fault slip behaviours including slow earthquakes, tremor and low-frequency earthquakes. Laboratory and theoretical studies predict changes in seismic velocity before earthquake failure; however, tectonic faults fail in a spectrum of modes and little is known about precursors for those modes. Here we show that precursory changes of wave speed occur in laboratory faults for the complete spectrum of failure modes observed for tectonic faults. We systematically altered the stiffness of the loading system to reproduce the transition from slow to fast stick-slip and monitored ultrasonic wave speed during frictional sliding. We find systematic variations of elastic properties during the seismic cycle for both slow and fast earthquakes indicating similar physical mechanisms during rupture nucleation. Our data show that accelerated fault creep causes reduction of seismic velocity and elastic moduli during the preparatory phase preceding failure, which suggests that real-time monitoring of active faults may be a means to detect earthquake precursors.

  2. 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.

  3. Long-term lumen depreciation behavior and failure modes of multi-die array LEDs

    Science.gov (United States)

    Jayawardena, Asiri; Marcus, Daniel; Prugue, Ximena; Narendran, Nadarajah

    2013-09-01

    One of the main advantages of multi-die array light-emitting diodes (LEDs) is their high flux density. However, a challenge for using such a product in lighting fixture applications is the heat density and the need for thermal management to keep the junction temperatures of all the dies low for long-term reliable performance. Ten multi-die LED array samples for each product from four different manufacturers were subjected to lumen maintenance testing (as described in IES-LM-80-08), and their resulting lumen depreciation and failure modes were studied. The products were tested at the maximum case (or pin) temperature reported by the respective manufacturer by appropriately powering the LEDs. In addition, three samples for each product from two different manufacturers were subjected to rapid thermal cycling, and the resulting lumen depreciation and failure modes were studied. The results showed that the exponential lumen decay model using long-term lumen maintenance data as recommended in IES TM-21 does not fit for all package types. The failure of a string of dies and single die failure in a string were observed in some of the packages.

  4. Buried free flaps in head and neck reconstruction: higher risk of free flap failure?

    Science.gov (United States)

    Reiter, M; Harréus, U; Kisser, U; Betz, C S; Baumeister, Ph

    2017-01-01

    Thrombosis of the pedicle is central to free flap failure, and early revision of a compromised flap is the key to successfully salvage a flap. Therefore, the majority of free flaps in reconstructive head and neck surgery are used with the ability to visually examine the flap. Sometimes, due to intra-operative circumstances, it is necessary to use a flap that cannot be monitored externally. These flaps are called buried flaps and have the reputation of being put at risk. The current literature provides only limited data to support or disprove this position. A single institution retrospective review of patient charts between 2007 and 2015 was performed. Flap monitoring was carried out with hand-held Doppler of the pedicle hourly for the first 72 h in all cases. Additional duplex ultrasound was performed in the majority of buried flaps. A total of 437 flaps were included into the study. 37 flaps (7.8 %) were identified to fulfill the criteria of a buried free flap. In total, four patients had complications, three of which required operative reexploration. All interventions were successful, resulting in no flap loss in our series. An accurate operation technique combined with meticulous monitoring protocols supported by duplex ultrasound can result in satisfactory outcome of buried flaps. No enhanced risk of flap loss of buried flaps was found in our cohort.

  5. 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.

  6. 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.

  7. The assessment of low probability containment failure modes using dynamic PRA

    Science.gov (United States)

    Brunett, Acacia Joann

    Although low probability containment failure modes in nuclear power plants may lead to large releases of radioactive material, these modes are typically crudely modeled in system level codes and have large associated uncertainties. Conventional risk assessment techniques (i.e. the fault-tree/event-tree methodology) are capable of accounting for these failure modes to some degree, however, they require the analyst to pre-specify the ordering of events, which can vary within the range of uncertainty of the phenomena. More recently, dynamic probabilistic risk assessment (DPRA) techniques have been developed which remove the dependency on the analyst. Through DPRA, it is now possible to perform a mechanistic and consistent analysis of low probability phenomena, with the timing of the possible events determined by the computational model simulating the reactor behavior. The purpose of this work is to utilize DPRA tools to assess low probability containment failure modes and the driving mechanisms. Particular focus is given to the risk-dominant containment failure modes considered in NUREG-1150, which has long been the standard for PRA techniques. More specifically, this work focuses on the low probability phenomena occurring during a station blackout (SBO) with late power recovery in the Zion Nuclear Power Plant, a Westinghouse pressurized water reactor (PWR). Subsequent to the major risk study performed in NUREG-1150, significant experimentation and modeling regarding the mechanisms driving containment failure modes have been performed. In light of this improved understanding, NUREG-1150 containment failure modes are reviewed in this work using the current state of knowledge. For some unresolved mechanisms, such as containment loading from high pressure melt ejection and combustion events, additional analyses are performed using the accident simulation tool MELCOR to explore the bounding containment loads for realistic scenarios. A dynamic treatment in the

  8. 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.

  9. Reliability, failure modes, and degradation mechanisms in high power single- and multi-mode InGaAs-AlGaAs strained quantum well lasers

    Science.gov (United States)

    Sin, Yongkun; Presser, Nathan; Lingley, Zachary; Brodie, Miles; Foran, Brendan; Moss, Steven C.

    2016-03-01

    High power single-mode (SM) and multi-mode (MM) InGaAs-AlGaAs strained quantum well (QW) lasers are critical components for both telecommunications and potential space satellite communications systems. However, little has been reported on failure modes of state-of-the-art SM InGaAs-AlGaAs strained QW lasers although it is crucial to understand failure modes and underlying degradation mechanisms in developing these lasers that meet lifetime requirements for space satellite systems, where extremely high reliability of these lasers is required. Our present study addresses the aforementioned issues by performing long-term life tests under different test conditions followed by failure mode analysis (FMA) and physics of failure investigation. We performed long-term accelerated life-tests on state-of-the-art SM and MM InGaAs-AlGaAs strained QW lasers under ACC (automatic current control) mode. Our life-tests have accumulated over 25,000 test hours for SM lasers and over 35,000 test hours for MM lasers. FMA was performed on failed SM lasers using electron beam induced current (EBIC). This technique allowed us to identify failure types by observing dark line defects. All the SM failures we studied showed catastrophic and sudden degradation and all of these failures were bulk failures. Our group previously reported that bulk failure or COBD (catastrophic optical bulk damage) is the dominant failure mode of MM InGaAs-AlGaAs strained QW lasers. To the best of our knowledge, this is the first report demonstrating that the dominant failure mode of both SM and MM InGaAs-AlGaAs strained QW lasers is the bulk failure. Since degradation mechanisms responsible for COBD are still not well understood, we also employed other techniques including focused ion beam (FIB) processing and high-resolution TEM to further study dark line defects and dislocations in post-aged SM and MM lasers. Our long-term life test results and FMA results are reported.

  10. 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

  11. 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.

  12. 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...

  13. 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

  14. The Role of Head and Neck Squamous Cell Carcinoma Cancer Stem Cells in Tumorigenesis, Metastasis and Treatment Failure

    OpenAIRE

    2012-01-01

    Head and neck squamous cell cancer (HNSCC) is the 6th most common cancer worldwide. Despite advances in diagnostic and therapeutic methods, survival of HNSCC remains unchanged over the last 30 years with treatment failure and metastases being the strongest indicators of poor outcome. Cancer stem cells (CSC) have been identified in multiple other solid tumors, including breast, prostate and pancreatic carcinoma. Recently, a subpopulation of tumor cells has been identified in HNSCC based on the...

  15. The role of head and neck squamous cell carcinoma cancer stem cells in tumorigenesis, metastasis, and treatment failure

    OpenAIRE

    2012-01-01

    Head and neck squamous cell carcinoma (HNSCC) is the sixth most common cancer worldwide. Despite advances in diagnostic and therapeutic methods, survival of HNSCC remains unchanged over the last 30 years with treatment failure and metastases being the strongest indicators of poor outcome. Cancer stem cells (CSC) have been identified in multiple other solid tumors, including breast, prostate, and pancreatic carcinoma. Recently, a subpopulation of tumor cells has been identified in HNSCC based ...

  16. Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

    Science.gov (United States)

    Gabb, Timothy P.; Kantzos, Pete T.; Palsa, Bonnie; Telesman, Jack; Gayda, John; Sudbrack, Chantal K.

    2012-01-01

    Mechanical property requirements vary with location in nickel-based superalloy disks. In order to maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored grain microstructures. In this study, fatigue failure modes of a grain size transition zone in a dual microstructure disk were evaluated. A specialized heat treatment method was applied to produce varying grain microstructure in the bore to rim portions of a powder metallurgy processed nickel-based superalloy disk. The transition in grain size was concentrated in a zone of the disk web, between the bore and rim. Specimens were extracted parallel and transversely across this transition zone, and multiple fatigue tests were performed at 427 C and 704 C. Grain size distributions were characterized in the specimens, and related to operative failure initiation modes. Mean fatigue life decreased with increasing maximum grain size, going out through the transition zone. The scatter in limited tests of replicates was comparable for failures of uniform gage specimens in all transition zone locations examined.

  17. Failure modes and conditions of a cohesive, spherical body due to YORP spin-up

    CERN Document Server

    Hirabayashi, Masatoshi

    2015-01-01

    This paper presents transition of the failure mode of a cohesive, spherical body due to YORP spin-up. On the assumption that the distribution of materials in the body is homogeneous, failed regions first appearing in the body at different spin rates are predicted by comparing the yield condition of an elastic stress in the body. It is found that as the spin rate increases, the locations of the failed regions move from the equatorial surface to the central region. To avoid such failure modes, the body should have higher cohesive strength. The results by this model are consistent with those by a plastic finite element model. Then, this model and a two-layered-cohesive model first proposed by Hirabayashi et al. are used to classify possible evolution and disruption of a spherical body. There are three possible pathways to disruption. First, because of a strong structure, failure of the central region is dominant and eventually leads to a breakup into multiple components. Second, a weak surface and a weak interio...

  18. 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.

  19. Failure Modes and Causes for Swing and Lift Type Check Valves.

    Energy Technology Data Exchange (ETDEWEB)

    McElhaney, K.L.

    1997-12-31

    Prior to the recent work performed by Oak Ridge National Laboratory (ORNL)relative to nuclear industry check valve performance, no information was readily available regarding the failure characteristics of check valves based on valve type (e.g., swing check, lift check). Although it had been recognized by component experts that the two most significant factors in determining check valve performance were valve design (i.e., type) and operating conditions, no industry data was available relative to the former. In cooperation with the Nuclear Industry Check Valve Group (NIC), ORNL has reviewed and analyzed check valve failures from the Institute of Nuclear Power Operations` (INPOs`) Nuclear Plant Reliability Database System (NPRDS) according to several parameters,including valve type. Since the valve type identification is not inherently included within the NPRDS engineering record for each component, ORNL had to rely upon input from NIC, valve manufacturers, and catalogs to supply the missing information. As a result of this effort, approximately 77% of the check valve failures occurring during the 1991-1996 study period and nearly 62% of the overall installed population were identified according to type. This data provided the basis to perform previously unavailable cross-correlations between parameters such as valve type versus failure mode and failure cause. Design characteristics and service applications differ markedly among check valve types, resulting in discernible differences in performance. This paper focuses on the performance characteristics of swing and lift type check valves since failure and population distributions have shown these to be the two most common types employed in a wide range of nuclear plant applications.

  20. Current modes of failure in TKA: infection, instability, and stiffness predominate.

    Science.gov (United States)

    Le, David H; Goodman, Stuart B; Maloney, William J; Huddleston, James I

    2014-07-01

    Historically, polyethylene wear and its sequelae (osteolysis, late instability, aseptic loosening) were common causes for revision total knee arthroplasty (TKA). Recently, polyethylene manufacturing has become more consistent; furthermore, a clearer understanding of the importance of oxidation on polyethylene performance led to packaging of the polyethylene bearings in an inert environment. This improved the quality and consistency of polyethylene used in TKA, raising the question of whether different failure modes now predominate after TKA. The purpose of this study was to determine the current reasons for (1) early and (2) late failures after TKA at one high-volume arthroplasty center. We reviewed all first-time revision TKAs performed between 2001 and 2011 at one institution, yielding a group of 253 revision TKAs in 251 patients. Mean age at the time of revision was 64 years (SD 10 years). Mean time to revision was 35 months (SD 23 months). Preoperative evaluations, laboratory data, radiographs, and intraoperative findings were used to determine causes for revision. Early failure was defined as revision within 2 years of the index procedure. The primary failure mechanism was determined by the operating surgeon. Early failure accounted for 46% (116 of 253) of all revisions with infection (28 of 116 [24%]), instability (30 of 116 [26%]), and stiffness (21 of 116 [18%]) being the leading causes. Late failure accounted for 54% (137 of 253) of all revisions with the most common causes including infection (34 of 137 [25%]), instability (24 of 137 [18%]), and stiffness (19 of 253 [14%]). Polyethylene wear was implicated as the failure mechanism in 2% of early cases (two of 116) and 9% of late cases (13 of 137). In contrast to previous studies, wear-related implant failure in TKA was relatively uncommon in this series. Changes in polyethylene manufacturing, sterilization, and storage may have accounted for some of this difference; however, longer-term followup will

  1. Value of the post-operative CT in predicting delayed flap failures following head and neck cancer surgery

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bitna; Yoon, Dae Young; Seo, Young Lan; Park, Min Woo; Kwon, Kee Hwan; Rho, Young Soo; Chung, Chul Hoon [Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul (Korea, Republic of)

    2017-06-15

    To identify post-operative computed tomography (CT) findings associated with delayed flap failures following head and neck cancer surgery. We retrospectively reviewed 60 patients who underwent flap reconstruction after head and neck cancer surgery and post-operative (3–14 days) contrast-enhanced CT scans for suspected complications. Patients were divided into two groups: delayed flap failure patients (patients required flap revision) (n = 18) and flap success patients (n = 42). Clinical data (age, sex, T-stage, type of flap, and time interval between reconstruction surgery and CT) and post-operative CT findings of flap status (maximum dimension of the flap, intra- or peri-flap fluid collection and intra- or peri-flap air collection, fat infiltration within the flap, fistula to adjacent aerodigestive tract or skin, and enhanced vascular pedicle) were assessed and compared between the two groups. CT findings showed that the following flap anomalies were observed more frequently in the delayed flap failure group than in the flap success group: intra- or peri-flap fluid collection > 4 cm (61.1% vs. 23.8%, p < 0.05), intra- or peri-flap air collection > 2 cm (61.1% vs. 2.4%, p < 0.001), and fistula to adjacent aerodigestive tract or skin (44.4% vs. 0%, p < 0.001). The maximum dimension of the flap, fat infiltration within the flap, and enhanced vascular pedicle were not associated with delayed flap failures. A large amount of fluid or air collection and fistula are the CT findings that were associated with delayed flap failures in patients with suspected post-operative complications after head and neck cancer surgery.

  2. Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

    Science.gov (United States)

    Dong, Xin; Lu, Hao; Huang, Houxu; Hao, Yiqing; Xia, Yuanpu

    2017-06-01

    Water-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

  3. Failure Mode of the Water-filled Fractures under Hydraulic Pressure in Karst Tunnels

    Directory of Open Access Journals (Sweden)

    Dong Xin

    2017-06-01

    Full Text Available Water-filled fractures continue to grow after the excavation of karst tunnels, and the hydraulic pressure in these fractures changes along with such growth. This paper simplifies the fractures in the surrounding rock as flat ellipses and then identifies the critical hydraulic pressure values required for the occurrence of tensile-shear and compression-shear failures in water-filled fractures in the case of plane stress. The occurrence of tensile-shear fracture requires a larger critical hydraulic pressure than compression-shear failure in the same fracture. This paper examines the effects of fracture strike and lateral pressure coefficient on critical hydraulic pressure, and identifies compression-shear failure as the main failure mode of water-filled fractures. This paper also analyses the hydraulic pressure distribution in fractures with different extensions, and reveals that hydraulic pressure decreases along with the continuous growth of fractures and cannot completely fill a newly formed fracture with water. Fracture growth may be interrupted under the effect of hydraulic tensile shear.

  4. Classification and calculation of primary failure modes in bread production line

    Energy Technology Data Exchange (ETDEWEB)

    Tsarouhas, Panagiotis H. [Department of Standardization and Transportation of Products-Logistics, Alexander Technological Educational Institute of Thessaloniki, Agiou Dimitriou 93, 60100 Katerini, Hellas (Greece)], E-mail: ptsarouh@teilam.gr

    2009-02-15

    In this study, we describe the classification methodology over a 2-year period of the primary failure modes in categories based on failure data of bread production line. We estimate the probabilities of these categories applying the chi-square goodness of fit test, and we calculate their joint probabilities of mass function at workstation and line level. Then, we present numerical examples in order to predict the causes and frequencies of breakdowns for workstations and for the entire bread production line that will occur in the future. The methodology is meant to guide bread and bakery product manufacturers, improving the operation of the production lines. It can also be a useful tool to maintenance engineers, who wish to analyze and improve the reliability and efficiency of the manufacturing systems.

  5. 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.

  6. List-Mode PET Motion Correction Using Markerless Head Tracking: Proof-of-Concept With Scans of Human Subject

    DEFF Research Database (Denmark)

    Olesen, Oline Vinter; Sullivan, Jenna M.; Mulnix, Tim

    2013-01-01

    scanner. Head motion was independently measured, with a commercial marker-based device and the proposed vision-based system. A list-mode event-by-event reconstruction algorithm using the detected motion was applied. A phantom study with hand-controlled continuous random motion was obtained. Motion...

  7. 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

  8. Capacities and failure modes of suction bucket foundation with internal bulkheads

    Science.gov (United States)

    Xiao, Zhong; Ge, Borui; Wang, Yan

    2017-08-01

    Suction bucket foundations can be divided into four compartments by cruciform internal bulkheads, thereby yielding better capacity in certain conditions than those without internal bulkheads. As yet, no systematic study has been conducted regarding the effects of cruciform internal bulkheads on the capacities of suction bucket foundations. In this study, we established a large number of finite element models of suction bucket foundations with and without cruciform internal bulkheads and of solid embedded circular foundations. We found the uniaxial capacities and failure modes of suction bucket foundations with various depth ratios to remain basically unaffected by internal bulkheads in uniform clays. However, in inhomogeneous clay with high strength heterogeneity, we observed the uniaxial moment and horizontal capacities and corresponding failure modes of suction bucket foundations with a low depth ratio to be obviously affected by internal bulkheads. In this case, the uniaxial moment capacities, in particular, as well as the horizontal capacities of suction bucket foundations with cruciform internal bulkheads become obviously greater than those without internal bulkheads. Under combined loading, we found the failure envelopes of suction bucket foundations with and without cruciform internal bulkheads and of solid circular foundation to also be basically consistent in uniform clays. However, in inhomogeneous clay with high strength heterogeneity, cruciform internal bulkheads can obviously change the shapes of the failure envelopes of bucket foundations with a small depth ratio. We conclude that when the acting vertical load or foundation depth is relatively small, suction bucket foundations with cruciform internal bulkheads can be subjected to larger moment and horizontal loads in soft clays with high strength heterogeneity.

  9. Pretreatment nutritional status and locoregional failure of patients with head and neck cancer undergoing definitive concurrent chemoradiation therapy.

    Science.gov (United States)

    Platek, Mary E; Reid, Mary E; Wilding, Gregory E; Jaggernauth, Wainwright; Rigual, Nestor R; Hicks, Wesley L; Popat, Saurin R; Warren, Graham W; Sullivan, Maureen; Thorstad, Wade L; Khan, Mohamed K; Loree, Thom R; Singh, Anurag K

    2011-11-01

    This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity-modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN). We performed a retrospective chart review of 78 patients with SCCHN who received definitive CCRT. We compared patient factors, tumor characteristics, and nutritional status indicators between patients with and without locoregional failure. Fifteen of 78 patients (19%) experienced locoregional failure. Median follow-up for live patients was 38 months. On univariate analysis, pretreatment percentage of ideal body weight (%IBW) (p cancer undergoing definitive CCRT based on pretreatment %IBW should be examined further. Copyright © 2010 Wiley Periodicals, Inc.

  10. PRETREATMENT NUTRITIONAL STATUS AND LOCOREGIONAL FAILURE IN PATIENTS WITH HEAD AND NECK CANCER UNDERGOING DEFINITIVE CONCURRENT CHEMORADIATION THERAPY

    Science.gov (United States)

    Platek, Mary E.; Reid, Mary E.; Wilding, Gregory E.; Jaggernauth, Wainwright; Rigual, Nestor R.; Hicks, Wesley L.; Popat, Saurin R.; Warren, Graham W.; Sullivan, Maureen; Thorstad, Wade L.; Khan, Mohamed K.; Loree, Thom R.; Singh, Anurag K.

    2015-01-01

    Background This study was carried out to determine if markers of nutritional status predict for locoregional failure following intensity-modulated radiation therapy (IMRT) with concurrent chemoradiotherapy (CCRT) for squamous cell carcinoma of the head and neck (SCCHN). Methods We performed a retrospective chart review of 78 patients with SCCHN who received definitive CCRT. We compared patient factors, tumor characteristics, and nutritional status indicators between patients with and without locoregional failure. Results Fifteen of 78 patients (19%) experienced locoregional failure. Median follow-up for live patients was 38 months. On univariate analysis, pretreatment percentage of ideal body weight (%IBW) (p cancer undergoing definitive CCRT based on pre-treatment %IBW should be examined further. PMID:21990220

  11. 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.

  12. 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.

  13. 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...

  14. Predicting the occurrence of mixed mode failure associated with hydraulic fracturing, part 2 water saturated tests

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Stephen J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Broome, Scott Thomas [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Choens, Charles [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Barrow, Perry Carl [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-09-14

    Seven water-saturated triaxial extension experiments were conducted on four sedimentary rocks. This experimental condition was hypothesized more representative of that existing for downhole hydrofracture and thus it may improve our understanding of the phenomena. In all tests the pore pressure was 10 MPa and confirming pressure was adjusted to achieve tensile and transitional failure mode conditions. Using previous work in this LDRD for comparison, the law of effective stress is demonstrated in extension using this sample geometry. In three of the four lithologies, no apparent chemo-mechanical effect of water is apparent, and in the fourth lithology test results indicate some chemo-mechanical effect of water.

  15. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Directory of Open Access Journals (Sweden)

    Shuai Huang

    Full Text Available Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  16. Failure Mode Identification and End of Life Scenarios of Offshore Wind Turbines: A Review

    Directory of Open Access Journals (Sweden)

    Maria Martinez Luengo

    2015-08-01

    Full Text Available In 2007, the EU established challenging goals for all Member States with the aim of obtaining 20% of their energy consumption from renewables, and offshore wind is expected to be among the renewable energy sources contributing highly towards achieving this target. Currently wind turbines are designed for a 25-year service life with the possibility of operational extension. Extending their efficient operation and increasing the overall electricity production will significantly increase the return on investment (ROI and decrease the levelized cost of electricity (LCOE, considering that Capital Expenditure (CAPEX will be distributed over a larger production output. The aim of this paper is to perform a detailed failure mode identification throughout the service life of offshore wind turbines and review the three most relevant end of life (EOL scenarios: life extension, repowering and decommissioning. Life extension is considered the most desirable EOL scenario due to its profitability. It is believed that combining good inspection, operations and maintenance (O&M strategies with the most up to date structural health monitoring and condition monitoring systems for detecting previously identified failure modes, will make life extension feasible. Nevertheless, for the cases where it is not feasible, other options such as repowering or decommissioning must be explored.

  17. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope

    Science.gov (United States)

    Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei

    2015-01-01

    Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping. PMID:26560103

  18. Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope.

    Science.gov (United States)

    Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei

    2015-01-01

    Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping.

  19. 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.

  20. Dynamic Response and Dynamic Failure Mode of a Weak Intercalated Rock Slope Using a Shaking Table

    Science.gov (United States)

    Fan, Gang; Zhang, Jianjing; Wu, Jinbiao; Yan, Kongming

    2016-08-01

    A large-scale shaking table test was performed to study the dynamic response of slopes parallel to geological bedding (bedding slopes) and slopes that cross-cut geological bedding (counter-bedding slopes). The test results show that the acceleration amplification coefficients increase with increasing elevation and, when the input earthquake amplitude is greater than 0.3 g, both bedding and counter-bedding slopes begin to show nonlinear dynamic response characteristics. With increasing elevation, the displacement of the bedding slope surface increases greatly. Conversely, the displacement of the counter-bedding slope surface increases first and then decreases; the slope develops a bulge at the relative elevation of 0.85. The displacement of the bedding slope surface is greater than that of the counter-bedding slope. The counter-bedding slope is more seismically stable compared with the bedding slope. Based on the Hilbert-Huang transform and marginal spectrum theories, the processes that develop dynamic damage of the bedding and counter-bedding slopes are identified. It is shown that the dynamic failure mode of the bedding slope is mainly represented by vertical tensile cracks at the rear of the slope, bedding slide of the strata along the weak intercalation, and rock collapse from the slope crest. However, the dynamic failure mode of the counter-bedding slope is mainly represented by staggered horizontal and vertical fissures, extrusion of the weak intercalation, and breakage at the slope crest.

  1. 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.

  2. An unusual mode of failure of a tripolar constrained acetabular liner: a case report.

    LENUS (Irish Health Repository)

    Banks, Louisa N

    2012-02-01

    Dislocation after primary total hip arthroplasty (THA) is the most commonly encountered complication and is unpleasant for both the patient and the surgeon. Constrained acetabular components can be used to treat or prevent instability after primary total hip arthroplasty. We present the case of a 42-year-old female with a BMI of 41. At 18 months post-primary THA the patient underwent further revision hip surgery after numerous (more than 20) dislocations. She had a tripolar Trident acetabular cup (Stryker-Howmedica-Osteonics, Rutherford, New Jersey) inserted. Shortly afterwards the unusual mode of failure of the constrained acetabular liner was noted from radiographs in that the inner liner had dissociated from the outer. The reinforcing ring remained intact and in place. We believe that the patient\\'s weight, combined with poor abductor musculature caused excessive demand on the device leading to failure at this interface when the patient flexed forward. Constrained acetabular components are useful implants to treat instability but have been shown to have up to 42% long-term failure rates with problems such as dissociated inserts, dissociated constraining rings and dissociated femoral rings being sited. Sometimes they may be the only option left in difficult cases such as illustrated here, but still unfortunately have the capacity to fail in unusual ways.

  3. Distinct failure modes in bio-inspired 3D-printed staggered composites under non-aligned loadings

    Science.gov (United States)

    Slesarenko, Viacheslav; Kazarinov, Nikita; Rudykh, Stephan

    2017-03-01

    The superior mechanical properties of biological materials originate in their complex hierarchical microstructures, combining stiff and soft constituents at different length scales. In this work, we employ a three-dimensional multi-materials printing to fabricate the bio-inspired staggered composites, and study their mechanical properties and failure mechanisms. We observe that bio-inspired staggered composites with inclined stiff tablets are able to undergo two different failure modes, depending on the inclination angle. We find that such artificial structure demonstrates high toughness only under loading applied at relatively small angle to the tablets stacking direction, while for higher angles the composites fail catastrophically. This aspect of the failure behavior was captured experimentally as well as by means of the finite element analysis. We show that even a relatively simple failure model with a strain energy limiter, can be utilized to qualitatively distinguish these two different modes of failure, occurring in the artificial bio-inspired composites.

  4. A CRITICAL ANALYSIS OF MANAGERIAL SKILLS COMPETENCIES OF SECONDARY SCHOOL HEADS TRAINED THROUGH DISTANCE MODE OF ALLAMA IQBAL OPEN UNIVERSITY

    Directory of Open Access Journals (Sweden)

    Muhammad AKHLAQ

    2010-07-01

    Full Text Available The premise of this article is to analyze the managerial skills competencies of secondary schools heads trained through distance mode of education in Pakistan. For this purpose a sample 300 secondary school teachers and 100 secondary schools head-teachers trained through distance mode and working in the Federal Government Educational Institutions (FGEI functioning under the administration of Pakistan army. The objectives of the study were: 1 to describe the M.Ed programme of AIOU, 2 to identify the managerial skills competencies of secondary school heads trained through Allama Iqbal Open University, 3 to find-out the managerial problems faced by the secondary school heads of FGEI, 4 to suggest some further suggestion to improve the managerial skills competencies of working heads of FGEI. The study focused the following categories of skills, Ø interpersonal communication skills, Ø planning skills, Ø collaboration/ teamwork skills, (iv proficiency skills, Ø organizational skills, Ø feedback skills, Ø basic technology knowledge, and Ø technology access knowledge. Major recommendations of the study were: 1 the scheme of study of M.Ed of Allama Iqbal Open University program be change as per need of administrator and it should focus be on management and administration, 2 For better performance of heads, an induction course covering all the managerial skills relevant to the job principal-sip should be arranged after each term and to be continue through out the service, 3 the present scheme of study of M.Ed program focus on teaching methodology, one additional semester be included that should cover the management courses and ,4 as the present study was delimited to the Federal Governmental Educational Institutions to analyze the managerial skills competencies of working heads of secondary schools. One logical avenue for future is to replicate this study on the whole the country to generalize the results.

  5. Observations of meteor-head echoes using the Jicamarca 50MHz radar in interferometer mode

    Directory of Open Access Journals (Sweden)

    J. L. Chau

    2004-01-01

    Full Text Available We present results of recent observations of meteor-head echoes obtained with the high-power large-aperture Jicamarca 50MHz radar (11.95°S, 76.87°W in an interferometric mode. The large power-aperture of the system allows us to record more than 3000 meteors per hour in the small volume subtended by the 1° antenna beam, albeit when the cluttering equatorial electrojet (EEJ echoes are not present or are very weak. The interferometry arrangement allows the determination of the radiant (trajectory and speed of each meteor. It is found that the radiant distribution of all detected meteors is concentrated in relative small angles centered around the Earth's Apex as it transits over the Jicamarca sky, i.e. around the corresponding Earth heading for the particular observational day and time, for all seasons observed so far. The dispersion around the Apex is ~18° in a direction transverse to the Ecliptic plane and only 8.5° in heliocentric longitude in the Ecliptic plane both in the Earth inertial frame of reference. No appreciable interannual variability has been observed. Moreover, no population related to the optical (larger meteors Leonid showers of 1998-2002 is found, in agreement with other large power-aperture radar observations. A novel cross-correlation detection technique (adaptive match-filtering is used in combination with a 13 baud Barker phase-code. The technique allows us to get good range resolution (0.75km without any sensitivity deterioration for the same average power, compared to the non-coded long pulse scheme used at other radars. The matching Doppler shift provides an estimation of the velocity within a pulse with the same accuracy as if a non-coded pulse of the same length had been used. The velocity distribution of the meteors is relatively narrow and centered around 60kms-1. Therefore most of the meteors have an almost circular retrograde orbit around the Sun. Less than 8% of the velocities correspond to interstellar orbits

  6. 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.

  7. Binary choice health state valuation and mode of administration: head-to-head comparison of online and CAPI.

    Science.gov (United States)

    Mulhern, Brendan; Longworth, Louise; Brazier, John; Rowen, Donna; Bansback, Nick; Devlin, Nancy; Tsuchiya, Aki

    2013-01-01

    Health state valuation exercises can be conducted online, but the quality of data generated is unclear. To investigate whether responses to binary choice health state valuation questions differ by administration mode: online versus face to face. Identical surveys including demographic, self-reported health status, and seven types of binary choice valuation questions were administered in online and computer-assisted personal interview (CAPI) settings. Samples were recruited following procedures employed in typical online or CAPI studies. Analysis included descriptive comparisons of the distribution of responses across the binary options and probit regression to explain the propensity to choose one option across modes of administration, controlling for background characteristics. Overall, 422 (221 online; 201 CAPI) respondents completed a survey. There were no overall age or sex differences. Online respondents were educated to a higher level than were the CAPI sample and general population, and employment status differed. CAPI respondents reported significantly better general health and health/life satisfaction. CAPI took significantly longer to complete. There was no effect of the mode of administration on responses to the valuation questions, and this was replicated when demographic differences were controlled. The findings suggest that both modes may be equally valid for health state valuation studies using binary choice methods (e.g., discrete choice experiments). There are some differences between the observable characteristics of the samples, and the groups may differ further in terms of unobservable characteristics. When designing health state valuation studies, the advantages and disadvantages of both approaches must be considered. Copyright © 2013 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

  8. Evaluation of detector readout gain mode and bowtie filters for cone-beam CT imaging of the head

    Science.gov (United States)

    Xu, Jennifer; Sisniega, Alejandro; Zbijewski, Wojciech; Dang, Hao; Webster Stayman, J.; Wang, Xiaohui; Foos, David H.; Aygun, Nafi; Koliatsos, Vassillis E.; Siewerdsen, Jeffrey H.

    2016-08-01

    The effects of detector readout gain mode and bowtie filters on cone-beam CT (CBCT) image quality and dose were characterized for a new CBCT system developed for point-of-care imaging of the head, with potential application to diagnosis of traumatic brain injury, intracranial hemorrhage (ICH), and stroke. A detector performance model was extended to include the effects of detector readout gain on electronic digitization noise. The noise performance for high-gain (HG), low-gain (LG), and dual-gain (DG) detector readout was evaluated, and the benefit associated with HG mode in regions free from detector saturation was quantified. Such benefit could be realized (without detector saturation) either via DG mode or by incorporation of a bowtie filter. Therefore, three bowtie filters were investigated that varied in thickness and curvature. A polyenergetic gain correction method was developed to equalize the detector response between the flood-field and projection data in the presence of a bowtie. The effect of bowtie filters on dose, scatter-to-primary ratio, contrast, and noise was quantified in phantom studies, and results were compared to a high-speed Monte Carlo (MC) simulation to characterize x-ray scatter and dose distributions in the head. Imaging in DG mode improved the contrast-to-noise ratio (CNR) by ~15% compared to LG mode at a dose (D 0, measured at the center of a 16 cm CTDI phantom) of 19 mGy. MC dose calculations agreed with CTDI measurements and showed that bowtie filters reduce peripheral dose by as much as 50% at the same central dose. Bowtie filters were found to increase the CNR per unit square-root dose near the center of the image by ~5-20% depending on bowtie thickness, but reduced CNR in the periphery by ~10-40%. Images acquired at equal CTDIw with and without a bowtie demonstrated a 24% increase in CNR at the center of an anthropomorphic head phantom. Combining a thick bowtie filter with a short arc (180°  +  fan angle) scan centered

  9. Evaluation of detector readout gain mode and bowtie filters for cone-beam CT imaging of the head.

    Science.gov (United States)

    Xu, Jennifer; Sisniega, Alejandro; Zbijewski, Wojciech; Dang, Hao; Stayman, J Webster; Wang, Xiaohui; Foos, David H; Aygun, Nafi; Koliatsos, Vassillis E; Siewerdsen, Jeffrey H

    2016-08-21

    The effects of detector readout gain mode and bowtie filters on cone-beam CT (CBCT) image quality and dose were characterized for a new CBCT system developed for point-of-care imaging of the head, with potential application to diagnosis of traumatic brain injury, intracranial hemorrhage (ICH), and stroke. A detector performance model was extended to include the effects of detector readout gain on electronic digitization noise. The noise performance for high-gain (HG), low-gain (LG), and dual-gain (DG) detector readout was evaluated, and the benefit associated with HG mode in regions free from detector saturation was quantified. Such benefit could be realized (without detector saturation) either via DG mode or by incorporation of a bowtie filter. Therefore, three bowtie filters were investigated that varied in thickness and curvature. A polyenergetic gain correction method was developed to equalize the detector response between the flood-field and projection data in the presence of a bowtie. The effect of bowtie filters on dose, scatter-to-primary ratio, contrast, and noise was quantified in phantom studies, and results were compared to a high-speed Monte Carlo (MC) simulation to characterize x-ray scatter and dose distributions in the head. Imaging in DG mode improved the contrast-to-noise ratio (CNR) by ~15% compared to LG mode at a dose (D 0, measured at the center of a 16 cm CTDI phantom) of 19 mGy. MC dose calculations agreed with CTDI measurements and showed that bowtie filters reduce peripheral dose by as much as 50% at the same central dose. Bowtie filters were found to increase the CNR per unit square-root dose near the center of the image by ~5-20% depending on bowtie thickness, but reduced CNR in the periphery by ~10-40%. Images acquired at equal CTDIw with and without a bowtie demonstrated a 24% increase in CNR at the center of an anthropomorphic head phantom. Combining a thick bowtie filter with a short arc (180°  +  fan angle) scan centered

  10. An efficient and robust maneuvering mode to calibrate low cost magnetometer for improved heading estimation for pedestrian navigation

    Science.gov (United States)

    Ali, A. S.; Siddharth, S.; Syed, Z.; Goodall, C. L.; El-Sheimy, N.

    2013-03-01

    Personal navigation systems intend to provide the navigation information in any environment, indoors and outdoors, and at any time. In outdoor environments, the positioning solution is typically provided by using Global Positioning System (GPS). However, GPS is inaccurate or unavailable in most of indoor environments and therefore other externally-referenced sensing techniques are required. Inertial sensing techniques are used for pedestrian navigation in association with dead reckoning approach. Magnetometers can be used to derive the user's heading by sensing the Earth's magnetic field. In this paper, an efficient and robust maneuvering mode to calibrate low cost magnetometer is recommended for pedestrian navigation applications. Additionally, other maneuvering modes and errors associated with each mode to achieve best estimation for the calibration parameters in the 3D Space are also provided. Also, the effect of using different maneuvering modes (DMM) on the heading estimation for the pedestrian navigation is studied. The results show that the coordinated mode is suitable to perform the calibration process as the unit is rotated in a way to cover the whole 3D space.

  11. 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.

  12. 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.

  13. 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.

  14. Comparison of Failure Modes in 2-D and 3-D Woven Carbon Phenolic Systems

    Science.gov (United States)

    Rossman, Grant A.; Stackpoole, Mairead; Feldman, Jay; Venkatapathy, Ethiraj; Braun, Robert D.

    2013-01-01

    NASA Ames Research Center is developing Woven Thermal Protection System (WTPS) materials as a new class of heatshields for entry vehicles (Stackpoole). Currently, there are few options for ablative entry heatshield materials, none of which is ideally suited to the planetary probe missions currently of interest to NASA. While carbon phenolic was successfully used for the missions Pioneer Venus and Galileo (to Jupiter), the heritage constituents are no longer available. An alternate carbon phenolic would need to be qualified for probe missions, which is most efficient at heat fluxes greater than those currently of interest. Additional TPS materials such as Avcoat and PICA are not sufficiently robust for the heat fluxes required. As a result, there is a large TPS gap between the materials efficient at very high conditions (carbon phenolic) and those that are effective at low-moderate conditions (all others). Development of 3D Woven TPS is intended to fill this gap, targeting mid-density weaves that could with withstand mid-range heat fluxes between 1100 W/sq cm and 8000 W/sq cm (Venkatapathy (2012). Preliminary experimental studies have been performed to show the feasibility of WTPS as a future mid-range TPS material. One study performed in the mARC Jet Facility at NASA Ames Research Center characterized the performance of a 3D Woven TPS sample and compared it to 2D carbon phenolic samples at ply angles of 0deg, 23.5deg, and 90deg. Each sample contained similar compositions of phenolic and carbon fiber volume fractions for experimental consistency. The goal of this study was to compare the performance of the TPS materials by evaluating resulting recession and failure modes. After exposing both samples to similar heat flux and pressure conditions, the 2D carbon phenolic laminate was shown to experience significant delamination between layers and further pocketing underneath separated layers. The 3D Woven TPS sample did not experience the delamination or pocketing

  15. 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.

  16. 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.

  17. Temperature effect on the performance of a dissipative dielectric elastomer generator with failure modes

    Science.gov (United States)

    Chen, S. E.; Deng, L.; He, Z. C.; Li, Eric; Li, G. Y.

    2016-05-01

    Research on dielectric elastomer generators (DEGs) which can be utilized to convert mechanical energy to electrical energy has gained wide attention lately. However, very few works account for the operating temperature, viscoelasticity and current leakage in the analysis of DEGs simultaneously. In this study, under several compound four-stroke conversion cycles, the electromechanical performance and energy conversion of a dissipative DEG made of a very-high-bond (VHB) elastomer are investigated at different operating temperatures. The performance parameters such as energy density and conversion efficiency are calculated under different temperatures. Moreover, the common failure modes of the generator are considered: material rupture, loss of tension, electrical breakdown and electromechanical instability. The numerical results have distinctly shown that the operating temperature plays an important role in the performance of DEGs, which could possibly make a larger conversion efficiency for the DEG.

  18. Properties of failure mode and thermal damage for limestone at high temperature

    Institute of Scientific and Technical Information of China (English)

    MAO Xian-biao; ZHANG Lian-ying; LI Tian-zhen; LIU Hai-shun

    2009-01-01

    The mechanical properties of limestone such as the stress-strain curve, the variable characteristics of peak strength and the modulus of elasticity of limestone were studied under the action of temperatures ranging from room temperature to 800℃. Our results show that: 1) the temperature has not clear effect on the mechanical properties of limestone from room temperature to 600 ℃. However, the mechanical properties of limestone deteriorate rapidly when the temperature is above 600 ℃. In this case, the peak stress and modulus of elasticity decrease rapidly. When the temperature reaches 800 ℃, the entire process, showing the stress-strain curve is displayed indicating an obvious state of plastic-deformation; 2) the failure mode of limestone shows the breakdown of tensile strength from room temperature to 600 ℃, as well as the compress shearing damage over 600 ℃; 3) combining our test results with the concept of thermal damage, a thermal damage equation was derived.

  19. Fracture Resistance and Failure Mode of Endodontically Treated Premolars Restored with Different Adhesive Restorations

    Directory of Open Access Journals (Sweden)

    Nasrin Sarabi

    2015-03-01

    Full Text Available Introduction: The restoration of endodontically treated teeth is a topic that has been studied extensively but it is still a challenge for dental practitioners. The aim of this study was to evaluate fracture resistance, fracture patterns and fracture location of endodontically treated human maxillary premolars restored with direct and indirect composite resin and ceramic restoration. Methods: Eighty non-carious maxillary premolars were selected and divided into four groups (n=20. Endodontic treatment and mesio-occluso-distal preparations were carried out in all the groups except for the control group (group I. Subsequently, the prepared teeth were restored as follows: group II: indirect composite restoration; group III: ceramic restoration; group IV: direct composite restoration. The specimens were subjected to compressive axial loading until fracture occurred. The mode of failure was also recorded. Results: Group I had higher fracture resistance (1196.82±241.74 than the other groups (P

  20. Changes of Some Capacities and Failure Mode of Ni/MH Batteries During Cycling

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The changes of capacities of positive and negative electrodes,reserve capacities of charging and discharging, and the weight of batteries during cycling have been determined. The increase of the discharging reserve capacity due to the conjugated electrochemical reactions of the oxidation of hydrogen-storage alloy is estimated. The results show that the failure mode of Ni/MH batteries developed is as follows: during the increase of cycles, the hydrogen-storage alloy is oxidized continuously and the charging reserve capacity is decreased rapidly while the discharging reserve capacity is increased gradually, thus the internal pressure is increasing, first H2 leaks out from the battery, then the mixture of H2 and O2. The leakage of gases and the total reaction of oxidation of the alloy consume H2O, and the surface oxides on the alloy increase, so that the internal resistance of the battery increases.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Fatigue resistance and failure mode of adhesively restored custom metal-composite resin premolar implant abutments.

    Science.gov (United States)

    Boff, Luís Leonildo; Oderich, Elisa; Cardoso, Antônio Carlos; Magne, Pascal

    2014-01-01

    To evaluate the fatigue resistance and failure mode of composite resin and porcelain onlays and crowns bonded to premolar custom metal-composite resin premolar implant abutments. Sixty composite resin mesostructures were fabricated with computer assistance with two preparation designs (crown vs onlay) and bonded to a metal implant abutment. Following insertion into an implant with a tapered abutment interface (Titamax CM), each metal-composite resin abutment was restored with either composite resin (Paradigm MZ100) or ceramic (Paradigm C) (n = 15) and attached with adhesive resin (Optibond FL) and a preheated light-curing composite resin (Filtek Z100). Cyclic isometric chewing (5 Hz) was then simulated, starting with 5,000 cycles at a load of 50 N, followed by stages of 200, 400, 600, 800, 1,000, 1,200, and 1,400 N (25,000 cycles each). Samples were loaded until fracture or to a maximum of 180,000 cycles. The four groups were compared using life table survival analysis (log-rank test). Previously published data using zirconia abutments of the same design were included for comparison. Paradigm C and MZ100 specimens fractured at average loads of 1,133 N and 1,266 N, respectively. Survival rates ranged from 20% to 33.3% (ceramic crowns and onlays) to 60% (composite resin crowns and onlays) and were significantly different (pooled data for restorative material). There were no restoration failures, but there were adhesive failures at the connection between the abutment and the mesostructure. The survival of the metal-composite resin premolar abutments was inferior to that of identical zirconia abutments from a previous study (pooled data for abutment material). Composite resin onlays/crowns bonded to metal-composite resin premolar implant abutments presented higher survival rates than comparable ceramic onlays/crowns. Zirconia abutments outperformed the metal-composite resin premolar abutments.

  8. 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.

  9. 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

  10. Adaptive Integral-type Sliding Mode Control for Spacecraft Attitude Maneuvering Under Actuator Stuck Failures

    Institute of Scientific and Technical Information of China (English)

    HU Qinglei; ZHANG Youmin; HUO Xing; XIAO Bing

    2011-01-01

    A fault tolerant control (FTC) design technique against actuator stuck faults is investigated using integral-type sliding mode control (ISMC) with application to spacecraft attitude maneuvering control system. The principle of the proposed FTC scheme is to design an integral-type sliding mode attitude controller using on-line parameter adaptive updating law to compensate for the effects of stuck actuators. This adaptive law also provides both the estimates of the system parameters and external disturbances such that a prior knowledge of the spacecraft inertia or boundedness of disturbances is not required. Moreover, by including the integral feedback term, the designed controller can not only tolerate actuator stuck faults, but also compensate the disturbances with constant components. For the synthesis of controller, the fault time, patterns and values are unknown in advance, as motivated from a practical spacecraft control application. Complete stability and performance analysis are presented and illustrative simulation results of application to a spacecraft show that high precise attitude control with zero steady-error is successfully achieved using various scenarios of stuck failures in actuators.

  11. A multi-component and multi-failure mode inspection model based on the delay time concept

    Energy Technology Data Exchange (ETDEWEB)

    Wang Wenbin, E-mail: w.wang@salford.ac.u [Salford Business School, University of Salford, Salford, M5 4WT (United Kingdom); PHM Centre of City University of Hong Kong (Hong Kong); Banjevic, Dragan [Department of Mechanical and Industrial Engineering, University of Toronto (Canada); Pecht, Michael [PHM Centre of City University of Hong Kong (Hong Kong); CALCE Electronic Products and Systems, University of Maryland, College Park, MD 20742 (United States)

    2010-08-15

    The delay time concept and the techniques developed for modelling and optimising plant inspection practices have been reported in many papers and case studies. For a system comprised of many components and subject to many different failure modes, one of the most convenient ways to model the inspection and failure processes is to use a stochastic point process for defect arrivals and a common delay time distribution for the duration between defect the arrival and failure of all defects. This is an approximation, but has been proven to be valid when the number of components is large. However, for a system with just a few key components and subject to few major failure modes, the approximation may be poor. In this paper, a model is developed to address this situation, where each component and failure mode is modelled individually and then pooled together to form the system inspection model. Since inspections are usually scheduled for the whole system rather than individual components, we then formulate the inspection model when the time to the next inspection from the point of a component failure renewal is random. This imposes some complication to the model, and an asymptotic solution was found. Simulation algorithms have also been proposed as a comparison to the analytical results. A numerical example is presented to demonstrate the model.

  12. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2006-04-28

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  13. Comparison of fracture strength and failure mode of different ceramic implant abutments.

    Science.gov (United States)

    Elsayed, Adham; Wille, Sebastian; Al-Akhali, Majed; Kern, Matthias

    2017-04-01

    The whitish color of zirconia (ZrO2) abutments offers favorable esthetics compared with the grayish color of titanium (Ti) abutments. Nonetheless, ZrO2 has greater opacity, making it difficult to achieve natural tooth color. Therefore, lithium disilicate (LaT) abutments have been suggested to replace metal abutments. The purpose of this in vitro study was to evaluate the fracture strength and failure mode of single-tooth implant restorations using ZrO2 and LaT abutments, and to compare them with titanium (Ti) abutments. Five different types of abutments, Ti; ZrO2 with no metal base; ZrO2 with a metal base (ZrT); LaT; and LaT combination abutment and crown (LcT) were assembled on 40 Ti implants and restored with LaT crowns. Specimens were subjected to quasistatic loading using a universal testing machine, until the implant-abutment connection failed. As bending of the metal would be considered a clinical failure, the values of force (N) at which the plastic deformation of the metal occurred were calculated, and the rate of deformation was analyzed. Statistical analysis was done using the Mann-Whitney U test (α=.05). Group ZrO2 revealed the lowest resistance to failure with a mean of 202 ±33 N. Groups ZrT, LaT, and LaC withstood higher forces without fracture or debonding of the ceramic suprastructure, and failure was due to deformation of metal bases, with no statistically significant differences between these groups regarding the bending behavior. Within the limitations of this in vitro study, it was concluded that LaT abutments have the potential to withstand the physiological occlusal forces that occur in the anterior region and that ZrO2 abutments combined with Ti inserts have much higher fracture strength than pure ZrO2 abutments. Copyright © 2016 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  14. Assessment of the Reliability ofFractionator Column of the Kaduna Refinery using Failure Modes Effects and Criticality Analysis (FMECA

    Directory of Open Access Journals (Sweden)

    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

  15. Testing Studies on Rock Failure Modes of Statically Loads Under Dynamic Loading

    Institute of Scientific and Technical Information of China (English)

    YE Zhouyuan; LI Xibing; LIU Xiling; MA Chunde; YIN Tubing

    2008-01-01

    By means of the improved split Hopkionson pressure bar(SHPB) with axial pre-pressure and confined pressure,two series of experiments on sandstone are earned out to research the failure mode of rock during the course of exploitation of resources in deep.One is under the conditions that the confining pressure is fixed and the axial pressure is changeable.The other is under the conditions that the confining pressure becomes and the axial pressure is fixed.It is found that samples break up evenly after impacting when axial static pressures are low,there is great disparity in size of fragments when axial static pressures are high,and the main bodies of samples after the tests under the combination of dynamic and static loads frequently show the type of V or X.The samples are more close-grained at the elastic stage and impacts make many cracks be generated and developed,as makes samples more crackable.At the initial phase of damage stage,the static pressures make some cracks in the samples which are undeveloped and the impacts' role is similar to that at the elastic stage.At the metaphase or anaphase of damage stage,these cracks in the samples develop adequately and the impacts mainly accelerate samples' failure.The main bodies of samples show the type of V or X after impacting due to the confining pressures' restraining samples' lateral formation at the elastic stage or the initial phase of damage stage,the main bodies of samples have almost formed at the stage loading static pressures and the results after impacting usually are similar to those under the axial pressures tests.

  16. Interim report on the state-of-the-art of solid-state motor controllers. Part 4. Failure-rate and failure-mode data

    Energy Technology Data Exchange (ETDEWEB)

    Jaross, R.A.

    1983-09-01

    An assessment of the reliability of solid-state motor controllers for nuclear power plants is made. Available data on failure-rate and failure-mode data for solid-state motor controllers based on industrial operating experience is meager; the data are augmented by data on other solid-state power electronic devices that are shown to have components similar to those found in solid-state motor controllers. In addition to large nonnuclear solid-state adjustable-speed motor drives, the reliability of nuclear plant inverter systems and high-voltage solid-state dc transmission-line converters is assessed. Licensee Event Report analyses from several sources, the open literature, and personal communications are used to determine the realiability of solid-state devices typical of those expected to be used in nuclear power plants in terms of failures per hour.

  17. Serum Leptin in Patients with Chronic Renal Failure on Different Modes of Management

    Directory of Open Access Journals (Sweden)

    Hala M. EL-Mougi*, Samiha Abo EL-Yazeed **, Zeinab A. Yousry

    2006-12-01

    Full Text Available Aim: To study serum leptin level in chronic renal failure (CRF patients on different modes of management and to analyze the impact of the mode of therapy on serum leptin level. Subjects and Methods: This study was conducted on 64 patients (33males&31females with chronic renal failure divided into three groups: group I: Twenty-six patients treated conservatively and did not start dialysis yet (predialysis, group II: Twenty-four patients treated by hemodialysis, group III: Fourteen patients treated by continuous ambulatory peritoneal dialysis (CAPD. Twenty healthy subjects were included as control group. All patients and controls were subjected to full clinical examination including height and weight to calculate body mass index (BMI. Blood urea and serum creatinine were measured as renal function tests. Serum leptin was measured by EASIA and so serum insulin. Results: In predialysis and CAPD groups, there is a significant increase in leptin , leptin/ BMI and insulin in patients in comparison to control subjects. In hemodialysis group, there is a significant increase in leptin and leptin/ BMI and a non-significant increase in insulin level in patients in comparison to control subjects. Insulin is significantly correlated with leptin in the first group, while in the second and third groups there is no correlation. The highest leptin level is found in the CAPD group of patients followed by the predialysis one then the hemodialysis group. Leptin level is significantly higher in females than males in all groups. This difference remained after adjusting leptin level to BMI. No correlation was found between leptin level and age or between leptin level and renal function in the three groups of patients. No correlation was found between leptin level and the duration of dialysis in the hemodialysis and CAPD groups. Conclusion: Serum leptin is elevated in CRF patients irrespective of the type of management they are undergoing. Dialysis, has no significant

  18. Modeling freedom from progression for standard-risk medulloblastoma: a mathematical tumor control model with multiple modes of failure

    DEFF Research Database (Denmark)

    Brodin, Nils Patrik; Vogelius, Ivan R.; Bjørk-Eriksson, Thomas

    2013-01-01

    As pediatric medulloblastoma (MB) is a relatively rare disease, it is important to extract the maximum information from trials and cohort studies. Here, a framework was developed for modeling tumor control with multiple modes of failure and time-to-progression for standard-risk MB, using publishe...

  19. Comprehensive characterization and failure modes of tungsten microwire arrays in chronic neural implants

    Science.gov (United States)

    Prasad, Abhishek; Xue, Qing-Shan; Sankar, Viswanath; Nishida, Toshikazu; Shaw, Gerry; Streit, Wolfgang J.; Sanchez, Justin C.

    2012-10-01

    activated microglia were present near the electrode tracks in all non-acute animals studied, thus indicating presence of a neuroinflammatory response regardless of post-implantation survival times and electrode performance. Conversely, dystrophic microglia detectable as fragmented cells were found almost exclusively in acute animals surviving only few hours after implantation. While there was no consistent relationship between microglial cell responses and electrode performance, we noticed co-occurrence of high ferritin expression, intraparenchymal bleeding, and microglial degeneration suggesting presence of excessive oxidative stress via Fenton chemistry. Biochemical analysis indicated that these electrodes always caused a persistent release of axonal injury biomarkers even several months after implantation suggesting persistent tissue damage. Our study suggests that mechanisms of electrode failure are multi-factorial involving both abiotic and biotic parameters. Since these failure modes occur concurrently and cannot be isolated from one another, the lack of consistent relationship between electrode performance and microglial responses in our results suggest that one or more of the abiotic factors were equally responsible for degradation in electrode performance over long periods of time.

  20. Fracture Resistance and Mode of Failure of Ceramic versus Titanium Implant Abutments and Single Implant-Supported Restorations.

    Science.gov (United States)

    Sghaireen, Mohd G

    2015-06-01

    The material of choice for implant-supported restorations is affected by esthetic requirements and type of abutment. This study compares the fracture resistance of different types of implant abutments and implant-supported restorations and their mode of failure. Forty-five Oraltronics Pitt-Easy implants (Oraltronics Dental Implant Technology GmbH, Bremen, Germany) (4 mm diameter, 10 mm length) were embedded in clear autopolymerizing acrylic resin. The implants were randomly divided into three groups, A, B and C, of 15 implants each. In group A, titanium abutments and metal-ceramic crowns were used. In group B, zirconia ceramic abutments and In-Ceram Alumina crowns were used. In group C, zirconia ceramic abutments and IPS Empress Esthetic crowns were used. Specimens were tested to failure by applying load at 130° from horizontal plane using an Instron Universal Testing Machine. Subsequently, the mode of failure of each specimen was identified. Fracture resistance was significantly different between groups (p ceramic crowns supported by titanium abutments (p = .000). IPS Empress crowns supported by zirconia abutments had the lowest fracture loads (p = .000). Fracture modes of metal-ceramic crowns supported by titanium abutments included screw fracture and screw bending. Fracture of both crown and abutment was the dominant mode of failure of In-Ceram/IPS Empress crowns supported by zirconia abutments. Metal-ceramic crowns supported by titanium abutments were more resistant to fracture than In-Ceram crowns supported by zirconia abutments, which in turn were more resistant to fracture than IPS Empress crowns supported by zirconia abutments. In addition, failure modes of restorations supported by zirconia abutments were more catastrophic than those for restorations supported by titanium abutments. © 2013 Wiley Periodicals, Inc.

  1. Analyzing planned maintenance (PM) inspection data by failure mode and effect analysis methodology.

    Science.gov (United States)

    Ridgway, Malcolm

    2003-01-01

    There is no question that medical devices are becoming more reliable. However, we have had some difficulty finding a satisfactory method for providing persuasive documentary evidence that this improved reliability will allow us to relax our traditional planned maintenance (PM) practices without compromising patient safety. The acceptance and increasing use of Failure Mode and Effect Analysis (FMEA) by several of the oversight agencies, including the Joint Commission on Accreditation of Healthcare Organizations, provides us with an important opportunity to take another shot at this vexing problem. Using this proven FMEA methodology and some relatively simple rules to quantify the results of the routine PM inspections that all healthcare providers are still performing in considerable abundance, we have developed a method that allows us to reduce the test results to a simple, single measure (the Risk Score) that can be used to characterize the effectiveness and levels of safety of our current PM regimens. When tested on theoretical data and a sample of real PM inspection results, the method provides answers that seem reasonable. Although it will probably require some modification as we begin the standardized data gathering and gain working experience, it is our hope that this new approach will become generally accepted within the industry. This kind of positive response should enable us to persuade the various accrediting and licensing agencies to similarly accept the concept.

  2. Effectiveness and cost of failure mode and effects analysis methodology to reduce neurosurgical site infections.

    Science.gov (United States)

    Hover, Alexander R; Sistrunk, William W; Cavagnol, Robert M; Scarrow, Alan; Finley, Phillip J; Kroencke, Audrey D; Walker, Judith L

    2014-01-01

    Mercy Hospital Springfield is a tertiary care facility with 32 000 discharges and 15 000 inpatient surgeries in 2011. From June 2009 through January 2011, a stable inpatient elective neurosurgery infection rate of 2.15% was observed. The failure mode and effects analysis (FMEA) methodology to reduce inpatient neurosurgery infections was utilized. Following FMEA implementation, overall elective neurosurgery infection rates were reduced to 1.51% and sustained through May 2012. Compared with baseline, the post-FMEA deep-space and organ infection rate was reduced by 41% (P = .052). Overall hospital inpatient clean surgery infection rates for the same time frame did not decrease to the same extent, suggesting a specific effect of the FMEA. The study team believes that the FMEA interventions resulted in 14 fewer expected infections, $270 270 in savings, a 168-day reduction in expected length of stay, and 22 fewer readmissions. Given the serious morbidity and cost of health care-associated infections, the study team concludes that FMEA implementation was clinically cost-effective.

  3. Hydrocephalus and Ventriculoperitoneal Shunts: Modes of Failure and Opportunities for Improvement.

    Science.gov (United States)

    Jorgensen, Julianne; Williams, Corin; Sarang-Sieminski, Alisha

    2016-01-01

    Between 0.5 and 4 of every 1000 children are born with hydrocephalus. Hydrocephalus is an over-accumulation of cerebrospinal fluid (CSF) in the ventricles of the brain, which can affect cognitive function, vision, appetite, and cranial nerve function. Left untreated, hydrocephalus can result in death. The current treatment for hydrocephalus uses ventriculoperitoneal (VP) shunts with valves to redirect CSF from the ventricles into the peritoneum. Shunt technology is limited by a number of complications, which include infection after implantation, shunt obstruction due to clot formation or catheter obstruction by scar tissue or choroid plexus, disconnection and tubing migration, and overdrainage or underdrainage of CSF due to valve malfunction. While modifications to surgical procedures and shunt design have been introduced, only modest improvements in outcomes have been observed. Here we provide an overview of hydrocephalus, VP shunts, and their modes of failure, and we identify numerous areas of opportunity for biomedical engineers and physicians to collaborate to improve the performance of VP shunts.

  4. Failure modes and effects analysis of total skin electron irradiation technique.

    Science.gov (United States)

    Ibanez-Rosello, B; Bautista, J A; Bonaque, J; Perez-Calatayud, J; Gonzalez-Sanchis, A; Lopez-Torrecilla, J; Brualla-Gonzalez, L; Garcia-Hernandez, T; Vicedo-Gonzalez, A; Granero, D; Serrano, A; Borderia, B; Solera, C; Rosello, J

    2017-08-04

    Total skin electron irradiation (TSEI) is a radiotherapy technique which consists of an homogeneous body surface irradiation by electrons. This treatment requires very strict technical and dosimetric conditions, requiring the implementation of multiple controls. Recently, the Task Group 100 report of the AAPM has recommended adapting the quality assurance program of the facility to the risks of their processes. A multidisciplinary team evaluated the potential failure modes (FMs) of every process step, regardless of the management tools applied in the installation. For every FM, occurrence (O), severity (S) and detectability (D) by consensus was evaluated, which resulted in the risk priority number (RPN), which permitted the ranking of the FMs. Subsequently, all the management tools used, related to the TSEI process, were examined and the FMs were reevaluated, to analyze the effectiveness of these tools and to propose new management tools to cover the greater risk FMs. 361 FMs were identified, 103 of which had RPN ≥80, initially, and 41 had S ≥ 8. Taking this into account the quality management tools FMs were reevaluated and only 30 FMs had RPN ≥80. The study of these 30 FMs emphasized that the FMs that involved greater risk were related to the diffuser screen placement and the patient's position during treatment. The quality assurance program of the facility has been adapted to the risk of this treatment process, following the guidelines proposed by the TG-100. However, clinical experience continually reveals new FMs, so the need for periodic risk analysis is required.

  5. Risk management for outsourcing biomedical waste disposal - using the failure mode and effects analysis.

    Science.gov (United States)

    Liao, Ching-Jong; Ho, Chao Chung

    2014-07-01

    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.

  6. Gravitational wave luminosity and net momentum flux in head-on mergers of black holes: Radiative patterns and mode mixing

    Science.gov (United States)

    Aranha, Rafael Fernandes; Soares, Ivano Damião; Tonini, Eduardo Valentino

    2016-09-01

    We show that gravitational wave radiative patterns from a point test particle falling radially into a Schwarzschild black hole, as derived by Davis, Ruffini, Press and Price [M. Davis et al., Phys. Rev. Lett. 27, 1466 (1971).], are present in the nonlinear regime of head-on mergers of black holes. We use the Bondi-Sachs characteristic formulation and express the gravitational wave luminosity and the net momentum flux in terms of the news functions. We then evaluate the (-2 )-spin-weighted ℓ-multipole decomposition of these quantities via exact expressions valid in the nonlinear regime and defined at future null infinity. Our treatment is made in the realm of Robinson-Trautman dynamics, with characteristic initial data corresponding to the head-on merger of two black holes. We consider mass ratios in the range 0.01 ≤α ≤1 . We obtain the exponential decay with ℓ of the total energy contributed by each multipole ℓ, with an accurate linear correlation in the log-linear plot of the points up to α ≃0.7 . Above this mass ratio the contribution of the odd modes to the energy decreases faster than that of the even modes, leading to the breaking of the linear correlation; for α =1 the energy in all odd modes is zero. The dominant contribution to the total radiated energy comes from the quadrupole mode ℓ=2 corresponding, for instance, to about ≃84 % for small mass ratios up to ≃99.8 % for the limit case α =1 . The total rescaled radiated energy EWtotal/m0α2 decreases linearly with decreasing α , yielding for the point particle limit α →0 the value ≃0.0484 , about 5 times larger than the result of Davis et al. [1]. The mode decomposition of the net momentum flux and of the associated gravitational wave impulses results in an adjacent-even-odd mode-mixing pattern. We obtain that the impulses contributed by each (ℓ,ℓ+1 ) mixed mode also accurately satisfy the exponential decay with ℓ, for the whole mass ratio domain considered, 0.01 ≤α 0

  7. Fuzzy Risk Evaluation in Failure Mode and Effects Analysis Using a D Numbers Based Multi-Sensor Information Fusion Method.

    Science.gov (United States)

    Deng, Xinyang; Jiang, Wen

    2017-09-12

    Failure mode and effect analysis (FMEA) is a useful tool to define, identify, and eliminate potential failures or errors so as to improve the reliability of systems, designs, and products. Risk evaluation is an important issue in FMEA to determine the risk priorities of failure modes. There are some shortcomings in the traditional risk priority number (RPN) approach for risk evaluation in FMEA, and fuzzy risk evaluation has become an important research direction that attracts increasing attention. In this paper, the fuzzy risk evaluation in FMEA is studied from a perspective of multi-sensor information fusion. By considering the non-exclusiveness between the evaluations of fuzzy linguistic variables to failure modes, a novel model called D numbers is used to model the non-exclusive fuzzy evaluations. A D numbers based multi-sensor information fusion method is proposed to establish a new model for fuzzy risk evaluation in FMEA. An illustrative example is provided and examined using the proposed model and other existing method to show the effectiveness of the proposed model.

  8. An assessment of BWR (boiling water reactor) Mark III containment challenges, failure modes, and potential improvements in performance

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, J.A.; Pafford, D.J.; Kelly, D.L.; Jones, K.R.; Dallman, F.J. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

    1991-01-01

    This report describes risk-significant challenges posed to Mark III containment systems by severe accidents as identified for Grand Gulf. Design similarities and differences between the Mark III plants that are important to containment performance are summarized. The accident sequences responsible for the challenges and the postulated containment failure modes associated with each challenge are identified and described. Improvements are discussed that have the potential either to prevent or delay containment failure, or to mitigate the offsite consequences of a fission product release. For each of these potential improvements, a qualitative analysis is provided. A limited quantitative risk analysis is provided for selected potential improvements. 21 refs., 5 figs., 46 tabs.

  9. List-mode PET motion correction using markerless head tracking: proof-of-concept with scans of human subject.

    Science.gov (United States)

    Olesen, Oline V; Sullivan, Jenna M; Mulnix, Tim; Paulsen, Rasmus R; Højgaard, Liselotte; Roed, Bjarne; Carson, Richard E; Morris, Evan D; Larsen, Rasmus

    2013-02-01

    A custom designed markerless tracking system was demonstrated to be applicable for positron emission tomography (PET) brain imaging. Precise head motion registration is crucial for accurate motion correction (MC) in PET imaging. State-of-the-art tracking systems applied with PET brain imaging rely on markers attached to the patient's head. The marker attachment is the main weakness of these systems. A healthy volunteer participating in a cigarette smoking study to image dopamine release was scanned twice for 2 h with (11)C-racolopride on the high resolution research tomograph (HRRT) PET scanner. Head motion was independently measured, with a commercial marker-based device and the proposed vision-based system. A list-mode event-by-event reconstruction algorithm using the detected motion was applied. A phantom study with hand-controlled continuous random motion was obtained. Motion was time-varying with long drift motions of up to 18 mm and regular step-wise motion of 1-6 mm. The evaluated measures were significantly better for motion-corrected images compared to no MC. The demonstrated system agreed with a commercial integrated system. Motion-corrected images were improved in contrast recovery of small structures.

  10. A Failure Mode in Dense Infrared Detector Arrays Resulting in Increased Dark Current

    Science.gov (United States)

    Pinkie, Benjamin; Bellotti, Enrico

    2016-09-01

    In this paper, we investigate a failure mode that arises in dense infrared focal plane detector arrays as a consequence of the interactions of neighboring pixels through the minority carrier profiles in the common absorber layer. We consider the situation in which one pixel in a hexagonal array becomes de-biased relative to its neighbors and show that the dark current in the six neighboring pixels increases exponentially as a function of the difference between the nominal and anomalous biases. Moreover, we show that the current increase in the six nearest-neighbor pixels is in total larger than that by which the current in the affected pixel decreases, causing a net increase in the dark current. The physical origins of this effect are explained as being due to increased lateral diffusion currents that arise as a consequence of breaking the symmetry of the minority carrier profiles. We then perform a parametric study to quantify the magnitude of this effect for a number of detector geometric parameters, operating temperatures, and spectral bands. Particularly, numerical simulations are carried out for short-, mid-, and long-wavelength HgCdTe infrared detectors operating between 77 K and 210 K. We show that this effect is most prevalent in architectures for which the lateral diffusion current is the largest component of the total dark current—high operating temperature devices with narrow epitaxial absorber thicknesses and pitches small compared to the diffusion length of minority carriers. These results could prove significant particularly for short- and mid-wave infrared detectors, which are typically designed to fit these conditions.

  11. Radiation therapy, an important mode of treatment for head and neck chemodectomas

    Energy Technology Data Exchange (ETDEWEB)

    Verniers, D.A. (Dr. Daniel den Hoad Cancer Centre, Rotterdam (Netherlands)); Keus, R.B.; Schouwenburg, P.F.; Bartelink, H. (Nederlands Kanker Inst. ' Antoni van Leeuwenhoekhuis' , Amsterdam (Netherlands))

    1992-05-01

    Between 1970 and 1990, 22 patients with 44 chemodectomas in the head and neck region were seen at the Netherlands Cancer Institute in Amsterdam. All patients were treated with radiation therapy (17 patients with radiation therapy only and 5 in combination with surgery). One patient was treated two times with an interval of 12 years at each side of the neck. Standard dose was 50 Gy in 25 fractions over 5 weeks. A radiation portal arrangement with oblique fields with paired wedges was used most frequently. The follow-up period ranged from 1 year to 20 years. Two recurrences at 2 and 9 years after treatment were observed. The actuarial local control rate was 88% at 10 years follow-up. Comparison of the results of surgery and radiotherapy demonstrates that radiation therapy is an effective treatment modality without mutilation or severe late morbidity for chemodectomas in the head and neck region. (Author).

  12. Matrix Failure Modes and Effects Analysis as a Knowledge Base for a Real Time Automated Diagnosis Expert System

    Science.gov (United States)

    Herrin, Stephanie; Iverson, David; Spukovska, Lilly; Souza, Kenneth A. (Technical Monitor)

    1994-01-01

    Failure Modes and Effects Analysis contain a wealth of information that can be used to create the knowledge base required for building automated diagnostic Expert systems. A real time monitoring and diagnosis expert system based on an actual NASA project's matrix failure modes and effects analysis was developed. This Expert system Was developed at NASA Ames Research Center. This system was first used as a case study to monitor the Research Animal Holding Facility (RAHF), a Space Shuttle payload that is used to house and monitor animals in orbit so the effects of space flight and microgravity can be studied. The techniques developed for the RAHF monitoring and diagnosis Expert system are general enough to be used for monitoring and diagnosis of a variety of other systems that undergo a Matrix FMEA. This automated diagnosis system was successfully used on-line and validated on the Space Shuttle flight STS-58, mission SLS-2 in October 1993.

  13. Application of ISO22000 and Failure Mode and Effect Analysis (fmea) for Industrial Processing of Poultry Products

    Science.gov (United States)

    Varzakas, Theodoros H.; Arvanitoyannis, Ioannis S.

    Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of poultry slaughtering and manufacturing. In this work comparison of ISO22000 analysis with HACCP is carried out over poultry slaughtering, processing and packaging. Critical Control points and Prerequisite programs (PrPs) have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram and fishbone diagram).

  14. Use of healthcare failure mode and effect analysis (HFMEA) to quantify risks of the human milk feeding process.

    Science.gov (United States)

    Zhang, Beilei Belinda; LaFleur, Elizabeth A; Ballweg, Diane D; Mulholland, Kristi L; Wild, Jodi A; Shedenhelm, Heidi J; Stirn, Susan L; Gannon, Janet L; Fjerstad, Kelly A; Morgenthaler, Timothy I

    2014-01-01

    The complexity of the expressed breast milk feeding process in the neonatal intensive care unit was not fully appreciated until we used a healthcare failure mode and effect analysis. This approach identified latent risks and provided semiquantitative estimates of the effectiveness of recommendations. Findings demonstrated nursing interruptions and multitasking requirements contributed to risk, emphasizing the need for focused and isolated expressed breast milk handling to improve patient safety and outcomes.

  15. Heat Transfer and Failure Mode Analyses of Ultrahigh-Temperature Ceramic Thermal Protection System of Hypersonic Vehicles

    OpenAIRE

    Tianbao Cheng; Weiguo Li; Wei Lu; Yushan Shi

    2014-01-01

    The transient temperature distribution of the ultrahigh-temperature ceramic (UHTC) thermal protection system (TPS) of hypersonic vehicles is calculated using finite volume method. Convective cooling enables a balance of heat increment and loss to be achieved. The temperature in the UHTC plate at the balance is approximately proportional to the surface heat flux and is approximately inversely proportional to the convective heat transfer coefficient. The failure modes of the UHTCs are presented...

  16. Probability of loss of assured safety in systems with multiple time-dependent failure modes.

    Energy Technology Data Exchange (ETDEWEB)

    Helton, Jon Craig; Pilch, Martin.; Sallaberry, Cedric Jean-Marie.

    2012-09-01

    Weak link (WL)/strong link (SL) systems are important parts of the overall operational design of high-consequence systems. In such designs, the SL system is very robust and is intended to permit operation of the entire system under, and only under, intended conditions. In contrast, the WL system is intended to fail in a predictable and irreversible manner under accident conditions and render the entire system inoperable before an accidental operation of the SL system. The likelihood that the WL system will fail to deactivate the entire system before the SL system fails (i.e., degrades into a configuration that could allow an accidental operation of the entire system) is referred to as probability of loss of assured safety (PLOAS). Representations for PLOAS for situations in which both link physical properties and link failure properties are time-dependent are derived and numerically evaluated for a variety of WL/SL configurations, including PLOAS defined by (i) failure of all SLs before failure of any WL, (ii) failure of any SL before failure of any WL, (iii) failure of all SLs before failure of all WLs, and (iv) failure of any SL before failure of all WLs. The effects of aleatory uncertainty and epistemic uncertainty in the definition and numerical evaluation of PLOAS are considered.

  17. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    Science.gov (United States)

    Zhao, Bo; Li, Chenghao; Liu, Derong; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

  18. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure.

    Directory of Open Access Journals (Sweden)

    Bo Zhao

    Full Text Available This paper considers a decentralized fault tolerant control (DFTC scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO. Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations.

  19. Quasi-Static Crushing Simulation Research and Failure Mode Analysis of Composite Thin-Walled C-Channel Specimen

    Directory of Open Access Journals (Sweden)

    XIE Jiang

    2017-04-01

    Full Text Available To study the crushing energy-absorbing characteristics and failure mode, the multi-shells finite element model of composite thin-walled C-channel specimen was established based on the quasi-static crushing test results. The simulation results show that the delamination failure, local buckling and beam bending failure of C-channel specimen can be simulated with the multi-shells finite element model. The load-displacement curve well fits the test results, and the deviation of initial peak load (Fmax, specific energy absorption (Es and crushing mean load (Fmean is small compared with the test results. The initial peak load of C-channel specimen is larger and the load efficiency is lower, so it is necessary to further reduce the initial peak load by the design optimization.

  20. FAILURE MODE EFFECTS AND CRITICALITY ANALYSIS (FMECA AS A QUALITY TOOL TO PLAN IMPROVEMENTS IN ULTRASONIC MOULD CLEANING SYSTEMS

    Directory of Open Access Journals (Sweden)

    Cristiano Fragassa

    2016-12-01

    Full Text Available Inside the complex process used for tire production, ultrasonic cleaning treatment probably represents the best solution to preserve the functionality of tire moulds, by removing residuals from moulds and keeping an unaltered quality for their surfaces. Ultrasonic Mould Cleaning Systems (UMCS is, however, a complicated technology that combines ultrasonic waves, high temperature and a succession of acid and basic attacks. At the same time, an UMCS plant, as part of a long productive chain, has to guarantee the highest productivity reducing failures and maintenances. This article describes the use of Failure Mode Effects and Criticality Analysis (FMECA as a methodology for improving quality in cleaning process. In particular, FMECA was utilized to identify potential defects in the original plant design, to recognize the inner causes of some failures actually occurred during operations and, finally, to suggest definitive re-design actions. Changes were implemented and the new UMCS offers a better quality in term of higher availability and productivity.

  1. Decentralized Sliding Mode Observer Based Dual Closed-Loop Fault Tolerant Control for Reconfigurable Manipulator against Actuator Failure

    Science.gov (United States)

    Zhao, Bo; Li, Yuanchun

    2015-01-01

    This paper considers a decentralized fault tolerant control (DFTC) scheme for reconfigurable manipulators. With the appearance of norm-bounded failure, a dual closed-loop trajectory tracking control algorithm is proposed on the basis of the Lyapunov stability theory. Characterized by the modularization property, the actuator failure is estimated by the proposed decentralized sliding mode observer (DSMO). Moreover, the actuator failure can be treated in view of the local joint information, so its control performance degradation is independent of other normal joints. In addition, the presented DFTC scheme is significantly simplified in terms of the structure of the controller due to its dual closed-loop architecture, and its feasibility is highly reflected in the control of reconfigurable manipulators. Finally, the effectiveness of the proposed DFTC scheme is demonstrated using simulations. PMID:26181826

  2. [Morphological and failure mode study of different fiber posts luted with different adhesive systems to root dentin].

    Science.gov (United States)

    Zhang, Xiao; Li, Jin-Le; Hao, Liang

    2011-04-01

    To investigate the correlation of morphological characteristics and failure modes of two types of glass-fiber posts luted with self-adhesive resin cement and etch-and-rinse adhesive system. Thirty-six intact single-rooted premolars were collected and removed the crown. After root canal therapy, teeth were randomly divided into 4 groups. Group A: Self-adhesive with POPO fiber post. Group B: Etch-and-rinse with POPO fiber posts. Group C: Self-adhesive with Para Post. Group D: Etch-and-rinse with Para Post. Each root was sectioned into six 1 mm-thick serial slices and a push-out test was performed. The dentin-cement-post adhesive interface of each specimen and failure modes after fracture were evaluated by stereomicroscope observation. Interface morphology observe indicated that voids present in group B (64.2%) and D (66.7%) were significantly higher than group A (5.8%) and C (13.7%) (P adhesive interface were discrepant with failure modes in different root region. There were interaction between adhesive systems and fiber posts.

  3. 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

  4. 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

  5. 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

  6. Designing a safer process to prevent retained surgical sponges: a healthcare failure mode and effect analysis.

    Science.gov (United States)

    Steelman, Victoria M; Cullen, Joseph J

    2011-08-01

    A retained surgical sponge is a sentinel event that can result in serious negative outcomes for the patient. Current standards rely on manual counting, the accuracy of which may be suspect, yet little is known about why counting fails to prevent retained sponges. The objectives of this project were to describe perioperative processes to prevent retained sponges after elective abdominal surgery; to identify potential failures; and to rate the causes, probability, and severity of these failures. A total of 57 potential failures were identified, associated with room preparation, the initial count, adding sponges, removing sponges, the first closing count, and the final closing count. The most frequently identified causes of failures included distraction, multitasking, not following procedure, and time pressure. Most of the failures are not likely to be affected by an educational intervention, so additional technological controls should be considered in efforts to improve safety.

  7. Comprehensive Reliability Allocation Method for CNC Lathes Based on Cubic Transformed Functions of Failure Mode and Effects Analysis

    Institute of Scientific and Technical Information of China (English)

    YANG Zhou; ZHU Yunpeng; REN Hongrui; ZHANG Yimin

    2015-01-01

    Reliability allocation of computerized numerical controlled(CNC) lathes is very important in industry. Traditional allocation methods only focus on high-failure rate components rather than moderate failure rate components, which is not applicable in some conditions. Aiming at solving the problem of CNC lathes reliability allocating, a comprehensive reliability allocation method based on cubic transformed functions of failure modes and effects analysis(FMEA) is presented. Firstly, conventional reliability allocation methods are introduced. Then the limitations of direct combination of comprehensive allocation method with the exponential transformed FMEA method are investigated. Subsequently, a cubic transformed function is established in order to overcome these limitations. Properties of the new transformed functions are discussed by considering the failure severity and the failure occurrence. Designers can choose appropriate transform amplitudes according to their requirements. Finally, a CNC lathe and a spindle system are used as an example to verify the new allocation method. Seven criteria are considered to compare the results of the new method with traditional methods. The allocation results indicate that the new method is more flexible than traditional methods. By employing the new cubic transformed function, the method covers a wider range of problems in CNC reliability allocation without losing the advantages of traditional methods.

  8. A reassessment of the potential for an alpha-mode containment failure and a review of the current understanding of broader fuel-coolant interaction issues. Second steam explosion review group workshop

    Energy Technology Data Exchange (ETDEWEB)

    Basu, S. [Nuclear Regulatory Commission, Washington, DC (United States); Ginsberg, T. [Brookhaven National Lab., Upton, NY (United States)

    1996-08-01

    This report summarizes the review and evaluation by experts of the current understanding of the molten fuel-coolant interaction (FCI) issues covering the complete spectrum of interactions, i.e., from mild quenching to very energetic interactions including those that could lead to the alpha-mode containment failure. Of the eleven experts polled, all but two concluded that the alpha-mode failure issue was resolved from a risk perspective, meaning that this mode of failure is of very low probability, that it is of little or no significance to the overall risk from a nuclear power plant, and that any further reduction in residual uncertainties is not likely to change the probability in an appreciable manner. To a lesser degree, discussions also took place on the broader FCI issues such as mild quenching of core melt during non-explosive FCI, and shock loading of lower head and ex-vessel support structures arising from explosive localized FCIs. These latter issues are relevant with regard to determining the efficacy of certain accident management strategies for operating reactors as well as for advanced light water reactors. The experts reviewed the status of understanding of the FCI phenomena in the context of these broader issues, identified residual uncertainties in the understanding, and recommended future research (both experimental and analytical) to reduce the uncertainties.

  9. Meteorological Satellites (METSAT) and Earth Observing System (EOS) Advanced Microwave Sounding Unit-A (AMSU-A) Failure Modes and Effects Analysis (FMEA) and Critical Items List (CIL)

    Science.gov (United States)

    1996-01-01

    This Failure Modes and Effects Analysis (FMEA) is for the Advanced Microwave Sounding Unit-A (AMSU-A) instruments that are being designed and manufactured for the Meteorological Satellites Project (METSAT) and the Earth Observing System (EOS) integrated programs. The FMEA analyzes the design of the METSAT and EOS instruments as they currently exist. This FMEA is intended to identify METSAT and EOS failure modes and their effect on spacecraft-instrument and instrument-component interfaces. The prime objective of this FMEA is to identify potential catastrophic and critical failures so that susceptibility to the failures and their effects can be eliminated from the METSAT/EOS instruments.

  10. Apollo CSM Power Generation System Design Considerations, Failure Modes and Lessons Learned

    Science.gov (United States)

    Interbartolo, Michael

    2009-01-01

    The objectives of this slide presentation are to: review the basic design criteria for fuel cells (FC's), review design considerations during developmental phase that affected Block I and Block II vehicles, summarize the conditions that led to the failure of components in the FC's, and state the solution implemented for each failure. It reviews the location of the fuel cells, the fuel cell theory the design criteria going into development phase and coming from the development phase, failures and solutions of Block I and II, and the lessons learned.

  11. SU-E-T-421: Failure Mode and Effects Analysis (FMEA) of Xoft Electronic Brachytherapy for the Treatment of Superficial Skin Cancers

    Energy Technology Data Exchange (ETDEWEB)

    Hoisak, J; Manger, R; Dragojevic, I [University of California San Diego, La Jolla, CA (United States)

    2015-06-15

    Purpose: To perform a failure mode and effects analysis (FMEA) of the process for treating superficial skin cancers with the Xoft Axxent electronic brachytherapy (eBx) system, given the recent introduction of expanded quality control (QC) initiatives at our institution. Methods: A process map was developed listing all steps in superficial treatments with Xoft eBx, from the initial patient consult to the completion of the treatment course. The process map guided the FMEA to identify the failure modes for each step in the treatment workflow and assign Risk Priority Numbers (RPN), calculated as the product of the failure mode’s probability of occurrence (O), severity (S) and lack of detectability (D). FMEA was done with and without the inclusion of recent QC initiatives such as increased staffing, physics oversight, standardized source calibration, treatment planning and documentation. The failure modes with the highest RPNs were identified and contrasted before and after introduction of the QC initiatives. Results: Based on the FMEA, the failure modes with the highest RPN were related to source calibration, treatment planning, and patient setup/treatment delivery (Fig. 1). The introduction of additional physics oversight, standardized planning and safety initiatives such as checklists and time-outs reduced the RPNs of these failure modes. High-risk failure modes that could be mitigated with improved hardware and software interlocks were identified. Conclusion: The FMEA analysis identified the steps in the treatment process presenting the highest risk. The introduction of enhanced QC initiatives mitigated the risk of some of these failure modes by decreasing their probability of occurrence and increasing their detectability. This analysis demonstrates the importance of well-designed QC policies, procedures and oversight in a Xoft eBx programme for treatment of superficial skin cancers. Unresolved high risk failure modes highlight the need for non-procedural quality

  12. Lunar Module Environmental Control System Design Considerations and Failure Modes. Part 2

    Science.gov (United States)

    Interbartolo, Michael A.

    2009-01-01

    This viewgraph presentation seeks to describe the Lunar Module Environmental Control System (ECS) subsystem testing and redesign and seeks to summarize the in-flight failures of the Lunar Module (LM) Environmental Control System (ECS).

  13. 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.

  14. Evaluation of the Prevalence of Different Treatment Failure Modes after Crown Lengthening Surgical Procedures

    Directory of Open Access Journals (Sweden)

    Amirreza Babaloo

    2016-07-01

    Full Text Available Introduction: Preservation of the health of periodontium is very important for the long-term success of restored teeth and a balance should always be created between the patients’ esthetic requirements and the periodontal health. Failures of crown lengthening procedures are classified into early and late failures. The aim of this study was to evaluate the prevalence of early failures of crown leathering surgical procedures. Materials and methods: In this descriptive/cross-sectional study, 96 patients were selected from those referring to the Department of Periodontitis, Tabriz Faculty of Dentistry, who required crown lengthening procedures. The particulars of these patients were recorded in special forms and the reasons for the failure of surgical procedures were separately determined at 2- and 6-week intervals. In addition, the frequencies of the reasons for failures were determined in percentages and absolute frequencies. Data were analyzed with descriptive statistics (frequencies and percentages using SPSS 21. Statistical significance was set at P<0.05. Results: Evaluation of patients 6 weeks after surgery showed a failure rate of 14.5% for crown lengthening procedures in patients referring to the Department of Periodontics, Tabriz Faculty of Dentistry. The most common reasons for such early failures in the 6th week, in descending order, were a lack of sufficient keratinized gingiva around in tooth in question, fracture of the tooth structure after surgery, inadequate surgery (not creating a proper distance between the healthy margin and the crest and the coronal returning of the gingival tissue on the tooth. A lack of sufficient keratinized gingiva around the tooth was the most frequent reason for the early failure of crown lengthening procedure at both study intervals. Conclusion: It can be concluded from the results of the present study that during the 6th postoperative week the crown lengthening procedures exhibited a 14.5% failure rate

  15. Strength Prediction and Failure Modes of Concrete Specimens Subjected to the Split Test

    DEFF Research Database (Denmark)

    Hoang, Linh Cao; Andersen, M.E.; Hansen, N.T.;

    2014-01-01

    tensile strength as crack propagation take place. The residual tensile strength is thereafter used in a rigid plastic analysis of the splitting failure. Based on this combined approach, the ultimate load may either be governed by crack propagation or by a plastic failure, which then terminates the crack...... growth process. It is shown that the model is able to replicate a number of experimental observations. This includes size effect and influence of loading width....

  16. 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.

  17. Wrinkling, fracture, and necking: The various failure modes in maritime crash

    NARCIS (Netherlands)

    Atli-Veltin, B.; Dekker, R.; Brunner, S.K.; Walters, C.L.

    2016-01-01

    Depending on the state of stress, material can fait in a number of different modes during a collision. Three modes are identified here as material separation in the absence of necking, material separation after the onset of necking, and localized buckling/wrinkling. Through a series of case studies,

  18. Identification of independent risk factors for flap failure: A retrospective analysis of 1530 free flaps for breast, head and neck and extremity reconstruction.

    Science.gov (United States)

    Las, David E; de Jong, Tim; Zuidam, J Michiel; Verweij, Norbert M; Hovius, Steven E R; Mureau, Marc A M

    2016-07-01

    Reconstructive microsurgery is a powerful method of treating various complex defects. However, flap loss remains a possibility, leading to additional surgery, hospitalisation and costs. Consequently, it is important to know which factors lead to an increased risk of flap failure, so that measures can be undertaken to reduce this risk. Therefore, we analysed our results over a 20-year period to identify risk factors for flap failure after breast, head and neck and extremity reconstruction. The medical files of all patients treated between 1992 and 2012 were reviewed. Patient characteristics, surgical data and post-operative complications were scored, and independent risk factors for flap loss were identified. Reconstruction with a total of 1530 free flaps was performed in 1247 patients. Partial and total flap loss occurred in 5.5% and 4.4% of all free flaps, respectively. In all flaps, signs of compromised flap circulation were a risk factor for flap failure. More specifically, the risk factors for flap failure in breast reconstruction were previous radiotherapy, venous anastomosis revision, gluteal artery perforator (GAP) flap choice and post-operative bleeding. In head and neck reconstruction, pulmonary co-morbidity and anastomosis to the lingual vein or superficial temporal artery were risk factors, whereas a radial forearm flap reduced the risk. In extremity reconstruction, diabetes, prolonged anaesthesia time and post-operative wound infection were risk factors. Independent pre-, intra- and post-operative risk factors for flap failure after microvascular breast, head and neck and extremity reconstruction were identified. These results may be used to improve patient counselling and to adjust treatment algorithms to further reduce the chance of flap failure.

  19. Effect of ferrule height and glass fibre post length on fracture resistance and failure mode of endodontically treated teeth.

    Science.gov (United States)

    Abdulrazzak, Shurooq S; Sulaiman, Eshamsul; Atiya, Basim K; Jamaludin, Marhazlinda

    2014-08-01

    The purpose of this study was to evaluate the combined effect of ferrule height and post length on fracture resistance and failure mode of endodontically treated teeth restored with glass fibre posts, composite resin cores and crowns. Ninety human maxillary central incisors were endodontically treated and divided into three groups (n = 30) according to the ferrule heights: 4, 2 and 0 mm, respectively. Post spaces in each group were prepared at 2/3, 1/2 and 1/3 of the root length (n = 10). The specimens were received fibre posts, composite resin core build up and cast metal crowns. After thermocycling, compressive static load was applied at an angle of 135° to the crowns. Two-way analysis of variance showed significant differences in the failure load in the ferrule height groups, no significant differences in post length groups and no significant interaction between ferrule heights and post lengths. More restorable failure modes were observed.

  20. Behavior and Failure Modes of Sandwich T-Joint Using Cohesive Zone Material Model and Contact Elements

    Science.gov (United States)

    Khalili, S. M. R.; Ghaznavi, A.

    2013-02-01

    One of the significant concerns of sandwich panels is their joints. T-joint is one the most common joint in sandwich structures. This paper deals with the numerical study of triangle T-joint under static loading. The results of numerical solution obtained by ANSYS modeling are verified with the results of experimental tests obtained in the literature. In general, the results obtained for anticipated failure load by numerical solution with the results of experimental test is in good agreement. Contact elements and cohesive zone material model are used to model the adhesive layer, hence debonding and fracture of adhesive is observed by the numerical modeling. Also, by using a written macro code in the ANSYS software, the ability of damage is explained for the core of sandwich panels; thus both the modes in fracture of T-joints (core shear failure in base panel and debonding of adhesive) are modeled. Core materials consist of Divinycell H100, H160, H250, and HCP70 are used for modeling sandwich panels, so that the function of joint is studied under different conditions of the sandwich core material. Nine different geometrical models are created by changing the base angle of the core triangle. The absorbed energy associated with different segments of the T-joint are used to investigate the effect of joint geometry and core material on the load transfer and failure mode of the T-joint.

  1. APPLICATION OF FAILURE MODE & EFFECT ANALYSIS (FMEA FOR CONTINUOUS QUALITY IMPROVEMENT - MULTIPLE CASE STUDIES IN AUTOMOBILE SMES

    Directory of Open Access Journals (Sweden)

    Jigar Doshi

    2017-06-01

    Full Text Available Failure Mode and Effects Analysis (FMEA is a quality tool used to identify potential failures and related effects on processes and products, so continuous improvement in quality can be achieved by reducing them. The purpose of this research paper is to showcase the contribution of FMEA to achieve Continuous Quality Improvement (CQI by multiple case study research. The outcome research conducted by implementing FMEA; one of the Auto Core Tools (ACTs, in the automobile Small and Medium Enterprises (SMEs in Gujarat, India is presented in this paper which depict various means of Continuous Quality Improvements. The case study based research was carried out in four automobile SMEs; all of them are supplied to automotive Original Equipment Manufacturer (OEM. The FMEA was implemented with the help of Cross Functional Team (CFT to identify the potential failure modes and effects, in overall effect on Continuous Quality Improvement. The outcome of FMEA at four companies' reveals the scope of improvement exists in the manufacturing process. Implementation of those improvement points shows the definite signs of continuous improvement of the quality of process and product as well. The FMEA and subsequent implementations had reduced the quality rejections around 3% to 4% in case companies.

  2. Use of risk assessment analysis by failure mode, effects, and criticality to reduce door-to-balloon time.

    Science.gov (United States)

    Khare, Rahul K; Nannicelli, Anna P; Powell, Emilie S; Seivert, Nicholas P; Adams, James G; Holl, Jane L

    2013-10-01

    The Centers for Medicare & Medicaid Services currently endorses a door-to-balloon time of 90 minutes or less for patients presenting to the emergency department (ED) with ST-segment elevation myocardial infarction. Recent evidence shows that a door-to-balloon time of 60 minutes significantly decreases inhospital mortality. We seek to use a proactive risk assessment method of failure mode, effects, and criticality analysis (FMECA) to evaluate door-to-balloon time process, to investigate how each component failure may affect the performance of a system, and to evaluate the frequency and the potential severity of harm of each failure. We conducted a 2-part study: FMECA of the door-to-balloon time system and process of care, and evaluation of a single institution's door-to-balloon time operational data using a retrospective observational cohort design. A multidisciplinary group of FMECA participants described the door-to-balloon time process to then create a comprehensive map and table listing all process steps and identified process failures, including their frequency, consequence, and causes. Door-to-balloon time operational data were assessed by "on" versus "off" hours. Fifty-one failure points were identified across 4 door-to-balloon time phases. Of the 12 high-risk failures, 58% occurred between ECG and catheterization laboratory activation. Total door-to-balloon time during on hours had a median time of 55 minutes (95% confidence interval 46 to 60 minutes) compared with 77 minutes (95% confidence interval 68 to 83 minutes) during off hours. The FMECA revealed clear areas of potential delay and vulnerability that can be addressed to decrease door-to-balloon time from 90 to 60 minutes. FMECAs can provide a robust assessment of potential risks and can serve as the platform for significant process improvement and system redesign for door-to-balloon time. Copyright © 2013 American College of Emergency Physicians. Published by Mosby, Inc. All rights reserved.

  3. An application of failure mode and effect analysis (FMEA to assess risks in petrochemical industry in Iran

    Directory of Open Access Journals (Sweden)

    Mehdi Kangavari

    2015-06-01

    Full Text Available Petrochemical industries have a high rate of accidents. Failure mode and effect analysis (FMEA is a systematic method and thus is capable of analyzing the risks of systems from concept phase to system disposal, detecting the failures in design stage, and determining the control measures and corrective actions for failures to reduce their impacts. The objectives of this research were to perform FMEA to identify risks in an Iranian petrochemical industry and determine the decrease of the risk priority number (RPN after implementation of intervention programs. This interventional study was performed at one petrochemical plant in Tehran, Iran in 2014. Relevant information about job categories and plant process was gathered using brainstorming techniques, fishbone diagram, and group decision making. The data were collected through interviews, observation, and documents investigations and was recorded in FMEA worksheets. The necessary corrective measures were performed on the basis of the results of initial FMEA. Forty eight failures were identified in welding unit by application of FMEA to assess risks. Welding processes especially working at height got the highest RPN. Obtained RPN for working at height before performing the corrective actions was 120 and the score was reduced to 96 after performing corrective measures. Calculated RPN for all processes was significantly reduced (p≤0.001 by implementing the corrective actions. Scores of RPN in all studied processes effectively decreased after performing corrective actions in a petrochemical industry. FMEA method is a useful tool for identifying risk intervention priorities and effectiveness in a studied petrochemical industry.

  4. The effect of transverse shear on the face sheets failure modes of sandwich beams loaded in three points bending

    Directory of Open Access Journals (Sweden)

    BOUROUIS FAIROUZ

    2012-04-01

    Full Text Available Sandwich beams loaded in three points bending may fail in several ways including tension or compression failure of facings. In this paper , The effect of the transverse shear on the face yielding and face wrinkling failure modes of sandwich beams loaded in three points bending have been studied, the beams were made of various composites materials carbon/epoxy, kevlar/epoxy, glass/epoxy at sequence [+θ/-θ]3s, [0°/90°]3s. . The stresses in the face were calculated using maximum stress criterion and the simple beam theory. The obtained different results show that the sandwich beams with carbon/epoxy, and glass/epoxy face sheets are the best materials, inreturn the kevlar /epoxy facing characterised by low resistance of transverse shear in compression and tensile.

  5. Failure Analysis of a New Irrigation Water Allocation Mode Based on Copula Approaches in the Zhanghe Irrigation District, China

    Directory of Open Access Journals (Sweden)

    Haoxin Li

    2016-06-01

    Full Text Available The risk analysis of an irrigation water allocation strategy based on physical mechanisms is critically important in practice. Conventional risk analysis only considers the role of the channel system and ignores the factors related to on-farm ponds. This paper proposes a channel-pond joint water supply mode (CPJM based on copula approaches. Two copulas, the Plackett copula and No.16 copula, are chosen and two types of analyses are carried out with the proposed mode: (1 a risk assessment of CPJM with joint probability and conditional probability; and (2 determination of the water supply strategy given the pond water supply frequency. With a case study of the second channel in the Zhanghe Irrigation District (ZID, Southern China, nine combinations of channel water supply frequency (CWSF and pond water supply frequency (PWSF are studied. The results reveal that the failure probabilities of the joint distribution and the conditional distribution of the CPJM are 0.02%–16.54% and 0.45%–33.08%, respectively, with corresponding return period of 42–5000 and 10–222 years. Nevertheless, a previous study has shown that the real probability is 33.3%, which means that the return period is equals to three years. Therefore, the objective failure evaluation of the irrigation water-use strategy is useful for water saving in this channel system. Moreover, the irrigation water allocation strategy can be determined and the failure charts relating the CWSF and PWSF can be obtained for a predetermined PWSF. Thus, the channel-pond joint water supply mode provides a more reasonable estimate of the irrigation water allocation strategy reliability.

  6. Failure modes and fracture origins of porcelain veneers on bilayer dental crowns.

    Science.gov (United States)

    Liu, Yihong; Liu, Guanghua; Wang, Yong; Shen, James Zhijian; Feng, Hailan

    2014-01-01

    The aims of this study were to determine the fracture origins and crack paths in the porcelain of clinically failed bilayer ceramic restorations and to reveal the correlation between the porcelain failures and material properties. Three clinically failed crowns of each material (bilayer zirconia crowns, galvano-ceramic crowns, and porcelain-fused-to-metal crowns) were collected and underwent failure analysis. The fractures found in porcelain veneers showed several characteristics including wear, Hertzian cone crack, chipping off, and delamination. The results indicated that the fracture origins and features of the porcelain in bilayer ceramic restorations might be affected by the rigidity of core materials and thickness of copings.

  7. Reliability analysis of multi-degree-of-freedom nonlinear random structure vibration systems with correlation failure modes

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Yimin; (张义民); WANG; Shun; (王; 顺); LIU; Qiaoling; (刘巧伶); WEN; Bangchun; (闻邦椿)

    2003-01-01

    Based on the generalized probabilistic finite element method, this paper presents an approximate solution technique for general multi-degree-of-freedom nonlinear random vibration systems with random parameters. The fourth-moment technique, maximum entropy theory and incomplete probability information theory are employed to systematically develop a reliability analysis method for dynamic random structural systems with correlation failure modes under unavailable joint probability density functions of basic random variables. The first passage problem of multi-degree-of-freedom nonlinear random vibration systems is solved.

  8. Flexible Control of Small Wind Turbines With Grid Failure Detection Operating in Stand-Alone and Grid-Connected Mode

    DEFF Research Database (Denmark)

    Teodorescu, Remus; Blaabjerg, Frede

    2004-01-01

    -locked loop controller is developed in order to detect the grid failure or recovery and switch the operation mode accordingly. A flexible digital signal processor (DSP) system that allows user-friendly code development and on-line tuning is used to implement and test the different control strategies. The back......-to-back power conversion configuration is chosen where the generator converter uses a built-in standard flux vector control to control the speed of the turbine shaft while the grid-side converter uses a standard pulse-width modulation active rectifier control strategy implemented in a DSP controller. The design...

  9. Shear Fracture of Dual Phase AHSS in the Process of Stamping: Macroscopic Failure Mode and Micro-level Metallographical Observation

    Science.gov (United States)

    Wang, Wurong; Wei, Xicheng; Yang, Jun; Shi, Gang

    2011-08-01

    Due to its excellent strength and formability combinations, dual phase (DP) steels offer the potential to improve the vehicle crashworthiness performance without increasing car body weight and have been increasingly used into new vehicles. However, a new type of crack mode termed as shear fracture is accompanied with the application of these high strength DP steel sheets. With the cup drawing experiment to identify the limit drawing ratio (LDR) of three DP AHSS with strength level from 600 MPa to 1000 MPa, the study compared and categorized the macroscopic failure mode of these three types of materials. The metallographical observation along the direction of crack was conducted for the DP steels to discover the micro-level propagation mechanism of the fracture.

  10. Reliability measurement for mixed mode failures of 33/11 kilovolt electric power distribution stations.

    Directory of Open Access Journals (Sweden)

    Faris M Alwan

    Full Text Available The reliability of the electrical distribution system is a contemporary research field due to diverse applications of electricity in everyday life and diverse industries. However a few research papers exist in literature. This paper proposes a methodology for assessing the reliability of 33/11 Kilovolt high-power stations based on average time between failures. The objective of this paper is to find the optimal fit for the failure data via time between failures. We determine the parameter estimation for all components of the station. We also estimate the reliability value of each component and the reliability value of the system as a whole. The best fitting distribution for the time between failures is a three parameter Dagum distribution with a scale parameter [Formula: see text] and shape parameters [Formula: see text] and [Formula: see text]. Our analysis reveals that the reliability value decreased by 38.2% in each 30 days. We believe that the current paper is the first to address this issue and its analysis. Thus, the results obtained in this research reflect its originality. We also suggest the practicality of using these results for power systems for both the maintenance of power systems models and preventive maintenance models.

  11. Mixed-mode failure strength of implant-cement interface specimens with varying surface roughness

    NARCIS (Netherlands)

    Zelle, J.G.; Janssen, D.; Peeters, S.; Brouwer, C.; Verdonschot, N.J.J.

    2011-01-01

    Aseptic loosening at the implant-cement interface is a well-documented cause of failure in joint arthroplasty. Traditionally, the strength of the implant-cement interface is determined using uni-axial normal and shear loading tests. However, during functional loading, the implant fixation sites are

  12. Stripper foil failure modes and cures at the Oak Ridge Spallation Neutron Source

    Directory of Open Access Journals (Sweden)

    M. A. Plum

    2011-03-01

    Full Text Available The Oak Ridge Spallation Neutron Source comprises a 1 GeV, 1.5 MW linear accelerator followed by an accumulator ring and a liquid mercury target. To manage the beam loss caused by the H^{0} excited states created during the H^{-} charge-exchange injection into the accumulator ring, the stripper foil is located inside one of the chicane dipoles. This has some interesting consequences that were not fully appreciated until the beam power reached about 840 kW. One consequence was sudden failure of the stripper foil system due to convoy electrons stripped from the incoming H^{-} beam, which circled around to strike the foil bracket and cause bracket failure. Another consequence is that convoy electrons can reflect back up from the electron catcher and strike the foil and bracket. An additional contributor to foil system failure is vacuum breakdown due to the charge developed on the foil by secondary electron emission. In this paper we detail these and other interesting failure mechanisms and describe the improvements we have made to mitigate them.

  13. Comparison of failure modes below footings on carbonate and silica sands

    NARCIS (Netherlands)

    Dijkstra, J.; Gaudin, C.; White, D.J.

    2013-01-01

    To investigate the differences in failure mechanisms beneath vertically loaded shallow foundations on silica and carbonate sands by way of particle image velocimetry analysis, 1g and centrifuge model tests have been performed. A comparison of silica and carbonate sand behaviour at low stresses and

  14. Comparison of failure modes below footings on carbonate and silica sands

    NARCIS (Netherlands)

    Dijkstra, J.; Gaudin, C.; White, D.J.

    2013-01-01

    To investigate the differences in failure mechanisms beneath vertically loaded shallow foundations on silica and carbonate sands by way of particle image velocimetry analysis, 1g and centrifuge model tests have been performed. A comparison of silica and carbonate sand behaviour at low stresses and l

  15. Compressive failure modes and parameter optimization of the trabecular structure of biomimetic fully integrated honeycomb plates.

    Science.gov (United States)

    Chen, Jinxiang; Tuo, Wanyong; Zhang, Xiaoming; He, Chenglin; Xie, Juan; Liu, Chang

    2016-12-01

    To develop lightweight biomimetic composite structures, the compressive failure and mechanical properties of fully integrated honeycomb plates were investigated experimentally and through the finite element method. The results indicated that: fracturing of the fully integrated honeycomb plates primarily occurred in the core layer, including the sealing edge structure. The morphological failures can be classified into two types, namely dislocations and compactions, and were caused primarily by the stress concentrations at the interfaces between the core layer and the upper and lower laminations and secondarily by the disordered short-fiber distribution in the material; although the fully integrated honeycomb plates manufactured in this experiment were imperfect, their mass-specific compressive strength was superior to that of similar biomimetic samples. Therefore, the proposed bio-inspired structure possesses good overall mechanical properties, and a range of parameters, such as the diameter of the transition arc, was defined for enhancing the design of fully integrated honeycomb plates and improving their compressive mechanical properties.

  16. The use of failure mode and effects analysis to construct an effective disposal and prevention mechanism for infectious hospital waste.

    Science.gov (United States)

    Ho, Chao Chung; Liao, Ching-Jong

    2011-12-01

    In recent times, the quality of medical care has been continuously improving in medical institutions wherein patient-centred care has been emphasized. Failure mode and effects analysis (FMEA) has also been promoted as a method of basic risk management and as part of total quality management (TQM) for improving the quality of medical care and preventing mistakes. Therefore, a study was conducted using FMEA to evaluate the potential risk causes in the process of infectious medical waste disposal, devise standard procedures concerning the waste, and propose feasible plans for facilitating the detection of exceptional cases of infectious waste. The analysis revealed the following results regarding medical institutions: (a) FMEA can be used to identify the risk factors of infectious waste disposal. (b) During the infectious waste disposal process, six items were scored over 100 in the assessment of uncontrolled risks: erroneous discarding of infectious waste by patients and their families, erroneous discarding by nursing staff, erroneous discarding by medical staff, cleaning drivers pierced by sharp articles, cleaning staff pierced by sharp articles, and unmarked output units. Therefore, the study concluded that it was necessary to (1) provide education and training about waste classification to the medical staff, patients and their families, nursing staff, and cleaning staff; (2) clarify the signs of caution; and (3) evaluate the failure mode and strengthen the effects.

  17. European Clearinghouse: Incidents related to reactivity management. Failure modes and corrective actions

    OpenAIRE

    BRUYNOOGHE Christiane; NOEL MARC

    2010-01-01

    This work is part of the European Clearinghouse on Nuclear Power Plant Operational Experience Feedback (NPP OEF) activity carried out at the Joint Research Centre/Institute for Energy (JRC/IE) with the participation of nine EU Regulatory Authorities. It investigates the 1999 Shika-1 criticality event together with other shortcomings in reactivity management reported to the IAEA Incident Reporting System in the period 1981-2008. The aim of the work was to identify reactivity control failure mo...

  18. SU-E-T-179: Clinical Impact of IMRT Failure Modes at Or Near TG-142 Tolerance Criteria Levels

    Energy Technology Data Exchange (ETDEWEB)

    Faught, J Tonigan; Balter, P; Johnson, J; Kry, S; Court, L; Stingo, F; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: Quantitatively assess the clinical impact of 11 critical IMRT dose delivery failure modes. Methods: Eleven step-and-shoot IMRT failure modes (FMs) were introduced into twelve Pinnacle v9.8 treatment plans. One standard and one highly modulated plan on the IROC IMRT phantom and ten previous H&N patient treatment plans were used. FMs included physics components covered by basic QA near tolerance criteria levels (TG-142) such as beam energy, MLC positioning, and MLC modeling. Resultant DVHs were compared to those of failure-free plans and the severity of plan degradation was assessed considering PTV coverage and OAR and normal tissue tolerances and used for FMEA severity scoring. Six of these FMs were physically simulated and phantom irradiations performed. TLD and radiochromic film results are used for comparison to treatment planning studies. Results: Based on treatment planning studies, the largest clinical impact from the phantom cases was induced by 2 mm systematic MLC shift in one bank with the combination of a D95% target under dose near 16% and OAR overdose near 8%. Cord overdoses of 5%–11% occurred with gantry angle, collimator angle, couch angle, MLC leaf end modeling, and MLC transmission and leakage modeling FMs. PTV coverage and/or OAR sparing was compromised in all FMs introduced in phantom plans with the exception of CT number to electron density tables, MU linearity, and MLC tongue-and-groove modeling. Physical measurements did not entirely agree with treatment planning results. For example, symmetry errors resulted in the largest physically measured discrepancies of up to 3% in the PTVs while a maximum of 0.5% deviation was seen in the treatment planning studies. Patient treatment plan study results are under analysis. Conclusion: Even in the simplistic anatomy of the IROC phantom, some basic physics FMs, just outside of TG-142 tolerance criteria, appear to have the potential for large clinical implications.

  19. MO-D-213-02: Quality Improvement Through a Failure Mode and Effects Analysis of Pediatric External Beam Radiotherapy

    Energy Technology Data Exchange (ETDEWEB)

    Gray, J; Lukose, R; Bronson, J; Chandler, B; Merchant, T; Farr, J [St. Jude Children’s Research Hospital, Memphis, TN (United States)

    2015-06-15

    Purpose: To conduct a failure mode and effects analysis (FMEA) as per AAPM Task Group 100 on clinical processes associated with teletherapy, and the development of mitigations for processes with identified high risk. Methods: A FMEA was conducted on clinical processes relating to teletherapy treatment plan development and delivery. Nine major processes were identified for analysis. These steps included CT simulation, data transfer, image registration and segmentation, treatment planning, plan approval and preparation, and initial and subsequent treatments. Process tree mapping was utilized to identify the steps contained within each process. Failure modes (FM) were identified and evaluated with a scale of 1–10 based upon three metrics: the severity of the effect, the probability of occurrence, and the detectability of the cause. The analyzed metrics were scored as follows: severity – no harm = 1, lethal = 10; probability – not likely = 1, certainty = 10; detectability – always detected = 1, undetectable = 10. The three metrics were combined multiplicatively to determine the risk priority number (RPN) which defined the overall score for each FM and the order in which process modifications should be deployed. Results: Eighty-nine procedural steps were identified with 186 FM accompanied by 193 failure effects with 213 potential causes. Eighty-one of the FM were scored with a RPN > 10, and mitigations were developed for FM with RPN values exceeding ten. The initial treatment had the most FM (16) requiring mitigation development followed closely by treatment planning, segmentation, and plan preparation with fourteen each. The maximum RPN was 400 and involved target delineation. Conclusion: The FMEA process proved extremely useful in identifying previously unforeseen risks. New methods were developed and implemented for risk mitigation and error prevention. Similar to findings reported for adult patients, the process leading to the initial treatment has an

  20. Safety and feasibility of STAT RAD: Improvement of a novel rapid tomotherapy-based radiation therapy workflow by failure mode and effects analysis.

    Science.gov (United States)

    Jones, Ryan T; Handsfield, Lydia; Read, Paul W; Wilson, David D; Van Ausdal, Ray; Schlesinger, David J; Siebers, Jeffrey V; Chen, Quan

    2015-01-01

    The clinical challenge of radiation therapy (RT) for painful bone metastases requires clinicians to consider both treatment efficacy and patient prognosis when selecting a radiation therapy regimen. The traditional RT workflow requires several weeks for common palliative RT schedules of 30 Gy in 10 fractions or 20 Gy in 5 fractions. At our institution, we have created a new RT workflow termed "STAT RAD" that allows clinicians to perform computed tomographic (CT) simulation, planning, and highly conformal single fraction treatment delivery within 2 hours. In this study, we evaluate the safety and feasibility of the STAT RAD workflow. A failure mode and effects analysis (FMEA) was performed on the STAT RAD workflow, including development of a process map, identification of potential failure modes, description of the cause and effect, temporal occurrence, and team member involvement in each failure mode, and examination of existing safety controls. A risk probability number (RPN) was calculated for each failure mode. As necessary, workflow adjustments were then made to safeguard failure modes of significant RPN values. After workflow alterations, RPN numbers were again recomputed. A total of 72 potential failure modes were identified in the pre-FMEA STAT RAD workflow, of which 22 met the RPN threshold for clinical significance. Workflow adjustments included the addition of a team member checklist, changing simulation from megavoltage CT to kilovoltage CT, alteration of patient-specific quality assurance testing, and allocating increased time for critical workflow steps. After these modifications, only 1 failure mode maintained RPN significance; patient motion after alignment or during treatment. Performing the FMEA for the STAT RAD workflow before clinical implementation has significantly strengthened the safety and feasibility of STAT RAD. The FMEA proved a valuable evaluation tool, identifying potential problem areas so that we could create a safer workflow

  1. [THE FAILURE MODES AND EFFECTS ANALYSIS FACILITATES A SAFE, TIME AND MONEY SAVING OPEN ACCESS COLONOSCOPY SERVICE].

    Science.gov (United States)

    Gingold-Belfer, Rachel; Niv, Yaron; Horev, Nehama; Gross, Shuli; Sahar, Nadav; Dickman, Ram

    2017-04-01

    Failure modes and effects analysis (FMEA) is used for the identification of potential risks in health care processes. We used a specific FMEA - based form for direct referral for colonoscopy and assessed it for procedurerelated perforations. Ten experts in endoscopy evaluated and computed the entire referral process, modes of preparation for the endoscopic procedure, the endoscopic procedure itself and the discharge process. We used FMEA assessing for likelihood of occurrence, detection and severity and calculated the risk profile number (RPN) for each of the above points. According to the highest RPN results we designed a specific open access referral form and then compared the occurrence of colonic perforations (between 2010 and 2013) in patients who were referred through the open access arm (Group 1) to those who had a prior clinical consultation (non-open access, Group 2). Our experts in endoscopy (5 physicians and 5 nurses) identified 3 categories of failure modes that, on average, reached the highest RPNs. We identified 9,558 colonoscopies in group 1, and 12,567 in group 2. Perforations were identified in three patients from the open access group (1:3186, 0.03%) and in 10 from group 2 (1:1256, 0.07%) (p = 0.024). Direct referral for colonoscopy saved 9,558 pre-procedure consultations and the sum of $850,000. The FMEA tool-based specific referral form facilitates a safe, time and money saving open access colonoscopy service. Our form may be adopted by other gastroenterological clinics in Israel.

  2. Applying micromechanic failure models for description of failure modes in the ductile-brittle transition region; Einsatz mikromechanischer Schaedigungsmodelle im sproed-duktilen Uebergangsbereich

    Energy Technology Data Exchange (ETDEWEB)

    Bernauer, G.

    1997-07-01

    The work reported was to examine whether the modified Gurson model and the Beremin model can be applied to the brittle-ductile transition region of a ferritic steel, and whether the material`s behaviour can be characterized with a failure model integrating the two models mentioned above into one. Any possible improvements of this approach were to be found. The report at first gives a brief list of terminology and formulas used. Chapter 3 explains the microscopic processes typically observed in the transition region in connection with the failure modes of ductile fracture and cleavage fracture, and shows possible approaches for modelling. Chapter 4 defines the specimens and materials, and chapter 5 explains the experiments as well as the microscopic analyses of the fracture surfaces. Chapter 6 presents subsequent calculations representing the processes observed. Based on the stress distributions thus derived, the Beremin model is re-examined for further development. Chapter 7 summarizes the results obtained. (orig./CB) [Deutsch] Ziel der Arbeit ist, zu untersuchen, ob das modifizierte Gurson-Modell und das Beremin-Modell im sproed-duktilen Uebergangsbereich eines ferritischen Stahls einsetzbar sind und ob das Werkstoffverhalten mit einem aus beiden Modellen kombinierten Schaedigungsmodell berechnet werden kann. Gegebenenfalls sind Verbesserungen herbeizufuehren. Die vorliegende Arbeit beginnt mit einer kurzen Einfuehrung der verwendeten Begriffe und Formalismen. In Kap. 3 werden die mikroskopischen Vorgaenge bei den im Uebergangsbereich typischerweise auftretenden Versagensarten duktiler Bruch und Spaltbruch vorgestellt und verschiedene Moeglichkeiten ihrer Modellierung aufgezeigt. Nach der Vorstellung des Probenwerkstoffs werden in Kap. 4 die Experimente beschrieben und die mikroskopischen Untersuchungen der Bruchflaechen in Kap. 5 dargestellt. Die Nachrechnungen der Experimente werden in Kap. 6 vorgestellt. Auf der Grundlage der dadurch bereitgestellten

  3. Applying micromechanic failure models for description of failure modes in the ductile-brittle transition region; Einsatz mikromechanischer Schaedigungsmodelle im sproed-duktilen Uebergangsbereich

    Energy Technology Data Exchange (ETDEWEB)

    Bernauer, G.

    1997-07-01

    The work reported was to examine whether the modified Gurson model and the Beremin model can be applied to the brittle-ductile transition region of a ferritic steel, and whether the material`s behaviour can be characterized with a failure model integrating the two models mentioned above into one. Any possible improvements of this approach were to be found. The report at first gives a brief list of terminology and formulas used. Chapter 3 explains the microscopic processes typically observed in the transition region in connection with the failure modes of ductile fracture and cleavage fracture, and shows possible approaches for modelling. Chapter 4 defines the specimens and materials, and chapter 5 explains the experiments as well as the microscopic analyses of the fracture surfaces. Chapter 6 presents subsequent calculations representing the processes observed. Based on the stress distributions thus derived, the Beremin model is re-examined for further development. Chapter 7 summarizes the results obtained. (orig./CB) [Deutsch] Ziel der Arbeit ist, zu untersuchen, ob das modifizierte Gurson-Modell und das Beremin-Modell im sproed-duktilen Uebergangsbereich eines ferritischen Stahls einsetzbar sind und ob das Werkstoffverhalten mit einem aus beiden Modellen kombinierten Schaedigungsmodell berechnet werden kann. Gegebenenfalls sind Verbesserungen herbeizufuehren. Die vorliegende Arbeit beginnt mit einer kurzen Einfuehrung der verwendeten Begriffe und Formalismen. In Kap. 3 werden die mikroskopischen Vorgaenge bei den im Uebergangsbereich typischerweise auftretenden Versagensarten duktiler Bruch und Spaltbruch vorgestellt und verschiedene Moeglichkeiten ihrer Modellierung aufgezeigt. Nach der Vorstellung des Probenwerkstoffs werden in Kap. 4 die Experimente beschrieben und die mikroskopischen Untersuchungen der Bruchflaechen in Kap. 5 dargestellt. Die Nachrechnungen der Experimente werden in Kap. 6 vorgestellt. Auf der Grundlage der dadurch bereitgestellten

  4. Canonical failure modes of real-time control systems: insights from cognitive theory

    Science.gov (United States)

    Wallace, Rodrick

    2016-04-01

    Newly developed necessary conditions statistical models from cognitive theory are applied to generalisation of the data-rate theorem for real-time control systems. Rather than graceful degradation under stress, automatons and man/machine cockpits appear prone to characteristic sudden failure under demanding fog-of-war conditions. Critical dysfunctions span a spectrum of phase transition analogues, ranging from a ground state of 'all targets are enemies' to more standard data-rate instabilities. Insidious pathologies also appear possible, akin to inattentional blindness consequent on overfocus on an expected pattern. Via no-free-lunch constraints, different equivalence classes of systems, having structure and function determined by 'market pressures', in a large sense, will be inherently unreliable under different but characteristic canonical stress landscapes, suggesting that deliberate induction of failure may often be relatively straightforward. Focusing on two recent military case histories, these results provide a caveat emptor against blind faith in the current path-dependent evolutionary trajectory of automation for critical real-time processes.

  5. Spaceflight-induced bone loss alters failure mode and reduces bending strength in murine spinal segments.

    Science.gov (United States)

    Berg-Johansen, Britta; Liebenberg, Ellen C; Li, Alfred; Macias, Brandon R; Hargens, Alan R; Lotz, Jeffrey C

    2016-01-01

    Intervertebral disc herniation rates are quadrupled in astronauts following spaceflight. While bending motions are main contributors to herniation, the effects of microgravity on the bending properties of spinal discs are unknown. Consequently, the goal of this study was to quantify the bending properties of tail discs from mice with or without microgravity exposure. Caudal motion segments from six mice returned from a 30-day Bion M1 mission and eight vivarium controls were loaded to failure in four-point bending. After testing, specimens were processed using histology to determine the location of failure, and adjacent motion segments were scanned with micro-computed tomography (μCT) to quantify bone properties. We observed that spaceflight significantly shortened the nonlinear toe region of the force-displacement curve by 32% and reduced the bending strength by 17%. Flight mouse spinal segments tended to fail within the growth plate and epiphyseal bone, while controls tended to fail at the disc-vertebra junction. Spaceflight significantly reduced vertebral bone volume fraction, bone mineral density, and trabecular thickness, which may explain the tendency of flight specimens to fail within the epiphyseal bone. Together, these results indicate that vertebral bone loss during spaceflight may degrade spine bending properties and contribute to increased disc herniation risk in astronauts.

  6. Failure Mode Analysis of Aluminium Alloy 2024-T3 in Double-Lap Bolted Joints with Single and Double Fasteners; A Numerical and Experimental Study

    Directory of Open Access Journals (Sweden)

    Khosro Fallahnezhad

    2015-06-01

    Full Text Available This paper aims to study the mechanical behaviour and failure mode of Al 2024-T3 in double-lap bolted joints. To accomplish this, the effect of geometric parameters was investigated in both configurations of single and double fasteners. Using ABAQUS/Standard, a three-dimensional finite element model was developed and verified against the experimental results of the joints loaded in tension. In general, double bolt joints were found to have greater load carrying capacities than single bolt joints (by 40%–49%. In single bolt joints, the plate width had insignificant effect on the behaviour of the joint under tensile loading; whereas, increasing the distance of the hole from the edge, considerably enhanced the strength of the joint. In double bolt joints, changing the edge distance had almost no effect on the behaviour of the joint. However, increasing the plate width from 25.4 to 30 mm increased the load carrying capacity by 28%. This study showed that in single bolt connections, with increasing the edge distance, the failure mode can favourably shift from shear-out to bearing. Also, double bolt joints with wider plates (increased width can beneficially shift the failure mode from net-tension to bearing. The geometric parameters were found to play an important role in controlling the failure mode so that catastrophic failure modes of net-tension and shear-out can be prevented in bolted joint.

  7. Quality risk analysis in a cGMP environment: multiple models for comprehensive failure mode identification during the computer system lifecycle.

    Science.gov (United States)

    Gervais, Brian; D'Arcy, Deirdre M

    2014-01-01

    Pharmaceutical quality systems use various inputs to ensure product quality and prevent failures that might have patient consequences. These inputs are generally data from failures that have already occurred, for example process deviations or customer complaints. Risk analysis techniques are well-established in certain other industries and have become of interest to pharmaceutical manufacturers because they allow potential quality failures to be predicted and mitigating action taken in advance of their occurring. Failure mode and effects analysis (FMEA) is one such technique, and in this study it was applied to implement a computerized manufacturing execution system in a pharmaceutical manufacturing environment. After introduction, the system was monitored to detect failures that did occur and these were analyzed to determine why the risk analysis method failed to predict them. Application of FMEA in other industries has identified weaknesses in predicting certain error types, specifically its dependence on other techniques to model risk situations and its poor analysis of non-hardware risks, such as human error, and this was confirmed in this study. Hierarchical holographic modeling (HHM), a technique for identifying risk scenarios in wide-scope analyses, was applied subsequently and identified additional potential failure modes. The technique for human error rate prediction (THERP) has previously been used for the quantitative analysis of human error risk and the event tree from this technique was adapted and identified further human error scenarios. These were input to the FMEA for prioritization and mitigation, thereby strengthening the risk analysis in terms of failure modes considered.

  8. 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.

  9. Functional failure modes cause-consequence logic suited for mobile robots used at scientific facilities

    CERN Document Server

    Khan, Douzi Imran; Bonnal, Pierre; Verma, A K

    2014-01-01

    The scientific facilities emitting ionizing radiation may have some significant failures and hazard issues, in and around their infrastructure. Significantly, this will also cause risks to workers and environment, which has led engineers to explore the use and implementation of mobile robots (MR), in order to reduce or eliminate such risks concerned with safety issues. Safe functioning of MR and the systems working at hazardous facilities is essential and therefore all the systems, structures and components (SSC) of a hazardous facility have to correspond to high reliability, availability, maintainability and safety (=RAMS) demands. RAMS characteristics have a causal relationship with the risks related to the facility systems availability, safety and life cycle costs. They also form the basis for the operating systems and MR performance, to carry out the desired functions. In this paper we have developed and presented a method for how to consider and model a SSC with respect to its desired functions and also ...

  10. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  11. 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.

  12. Application of ISO 22000 and Failure Mode and Effect Analysis (FMEA) for industrial processing of salmon: a case study.

    Science.gov (United States)

    Arvanitoyannis, Ioannis S; Varzakas, Theodoros H

    2008-05-01

    The Failure Mode and Effect Analysis (FMEA) model was applied for risk assessment of salmon manufacturing. A tentative approach of FMEA application to the salmon industry was attempted in conjunction with ISO 22000. Preliminary Hazard Analysis was used to analyze and predict the occurring failure modes in a food chain system (salmon processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points were identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram and fishbone diagram). In this work, a comparison of ISO 22000 analysis with HACCP is carried out over salmon processing and packaging. However, the main emphasis was put on the quantification of risk assessment by determining the RPN per identified processing hazard. Fish receiving, casing/marking, blood removal, evisceration, filet-making cooling/freezing, and distribution were the processes identified as the ones with the highest RPN (252, 240, 210, 210, 210, 210, 200 respectively) and corrective actions were undertaken. After the application of corrective actions, a second calculation of RPN values was carried out resulting in substantially lower values (below the upper acceptable limit of 130). It is noteworthy that the application of Ishikawa (Cause and Effect or Tree diagram) led to converging results thus corroborating the validity of conclusions derived from risk assessment and FMEA. Therefore, the incorporation of FMEA analysis within the ISO 22000 system of a salmon processing industry is anticipated to prove advantageous to industrialists, state food inspectors, and consumers.

  13. Unraveling the success and failure of mode coupling theory from consideration of entropy.

    Science.gov (United States)

    Nandi, Manoj Kumar; Banerjee, Atreyee; Sengupta, Shiladitya; Sastry, Srikanth; Bhattacharyya, Sarika Maitra

    2015-11-07

    We analyze the dynamics of model supercooled liquids in a temperature regime where predictions of mode coupling theory (MCT) are known to be valid qualitatively. In this regime, the Adam-Gibbs (AG) relation, based on an activation picture of dynamics, also describes the dynamics satisfactorily, and we explore the mutual consistency and interrelation of these descriptions. Although entropy and dynamics are related via phenomenological theories, the connection between MCT and entropy has not been argued for. In this work, we explore this connection and provide a microscopic derivation of the phenomenological Rosenfeld theory. At low temperatures, the overlap between the MCT power law regime and AG relation implies that the AG relation predicts an avoided divergence at Tc, the origin of which can be related to the vanishing of pair configurational entropy, which we find occurring at the same temperature. We also show that the residual multiparticle entropy plays an important role in describing the relaxation time.

  14. Unraveling the success and failure of mode coupling theory from consideration of entropy

    Science.gov (United States)

    Nandi, Manoj Kumar; Banerjee, Atreyee; Sengupta, Shiladitya; Sastry, Srikanth; Bhattacharyya, Sarika Maitra

    2015-11-01

    We analyze the dynamics of model supercooled liquids in a temperature regime where predictions of mode coupling theory (MCT) are known to be valid qualitatively. In this regime, the Adam-Gibbs (AG) relation, based on an activation picture of dynamics, also describes the dynamics satisfactorily, and we explore the mutual consistency and interrelation of these descriptions. Although entropy and dynamics are related via phenomenological theories, the connection between MCT and entropy has not been argued for. In this work, we explore this connection and provide a microscopic derivation of the phenomenological Rosenfeld theory. At low temperatures, the overlap between the MCT power law regime and AG relation implies that the AG relation predicts an avoided divergence at Tc, the origin of which can be related to the vanishing of pair configurational entropy, which we find occurring at the same temperature. We also show that the residual multiparticle entropy plays an important role in describing the relaxation time.

  15. Pinless Friction Stir Welding of AA2024-T3 Joint and Its Failure Modes

    Institute of Scientific and Technical Information of China (English)

    李文亚; 李锦锋; 张志函; 高大路; 王卫兵; 栾国红

    2014-01-01

    The joining of aluminum alloy sheets with thickness less than 2.0 mm is difficult via conventional friction stir welding owing to the defects in the joint, such as root flaw, keyhole and lazy S. In the present research, a newly designed pinless tool with involute grooves on its shoulder surface was applied to weld 1.5 mm thick AA2024-T3. The effects of the rotating speed and welding speed on the microstructure and mechanical properties of the joints were ana-lyzed. The experimental results showed that the root flaw and keyhole were successfully eliminated. The lazy S was also eliminated under the optimized welding parameters. The maximum tensile strength of the joints was 326 MPa, which is about 74.1% that of the base material. Moreover, all the tensile samples fractured from the retreating side. Two fracture modes were observed during the tensile tests, which are related with the lazy S.

  16. An assessment of BWR (boiling water reactor) Mark-II containment challenges, failure modes, and potential improvements in performance

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, D.L.; Jones, K.R.; Dallman, R.J. (EG and G Idaho, Inc., Idaho Falls, ID (USA)); Wagner, K.C. (Science Applications International Corp., Albuquerque, NM (USA))

    1990-07-01

    This report assesses challenges to BWR Mark II containment integrity that could potentially arise from severe accidents. Also assessed are some potential improvements that could prevent core damage or containment failure, or could mitigate the consequences of such failure by reducing the release of fission products to the environment. These challenges and improvements are analyzed via a limited quantitative risk/benefit analysis of a generic BWR/4 reactor with Mark II containment. Point estimate frequencies of the dominant core damage sequences are obtained and simple containment event trees are constructed to evaluate the response of the containment to these severe accident sequences. The resulting containment release modes are then binned into source term release categories, which provide inputs to the consequence analysis. The output of the consequences analysis is used to construct an overall base case risk profile. Potential improvements and sensitivities are evaluated by modifying the event tree spilt fractions, thus generating a revised risk profile. Several important sensitivity cases are examined to evaluate the impact of phenomenological uncertainties on the final results. 75 refs., 25 figs., 65 tabs.

  17. Evaluation of shear bond strength of porcelain bonded to laser welded titanium surface and determination of mode of bond failure.

    Science.gov (United States)

    Patil, Narendra P; Dandekar, Minal; Nadiger, Ramesh K; Guttal, Satyabodh S

    2010-09-01

    The aim of this study was to evaluate the shear bond strength of porcelain to laser welded titanium surface and to determine the mode of bond failure through scanning electron microscopy (SEM) and energy dispersive spectrophotometry (EDS). Forty five cast rectangular titanium specimens with the dimension of 10 mm x 8 mm x 1 mm were tested. Thirty specimens had a perforation of 2 mm diameter in the centre. These were randomly divided into Group A and B. The perforations in the Group B specimens were repaired by laser welding using Cp Grade II titanium wire. The remaining 15 specimens were taken as control group. All the test specimens were layered with low fusing porcelain and tested for shear bond strength. The debonded specimens were subjected to SEM and EDS. Data were analysed with 1-way analysis of variance and Student's t-test for comparison among the different groups. One-way analysis of variance (ANOVA) showed no statistically significant difference in shear bond strength values at a 5% level of confidence. The mean shear bond strength values for control group, Group A and B was 8.4 +/- 0.5 Mpa, 8.1 +/- 0.4 Mpa and 8.3 +/- 0.3 Mpa respectively. SEM/EDS analysis of the specimens showed mixed and cohesive type of bond failure. Within the limitations of the study laser welding did not have any effect on the shear bond strength of porcelain bonded to titanium.

  18. The use of failure mode and effect analysis in a radiation oncology setting: the Cancer Treatment Centers of America experience.

    Science.gov (United States)

    Denny, Diane S; Allen, Debra K; Worthington, Nicole; Gupta, Digant

    2014-01-01

    Delivering radiation therapy in an oncology setting is a high-risk process where system failures are more likely to occur because of increasing utilization, complexity, and sophistication of the equipment and related processes. Healthcare failure mode and effect analysis (FMEA) is a method used to proactively detect risks to the patient in a particular healthcare process and correct potential errors before adverse events occur. FMEA is a systematic, multidisciplinary team-based approach to error prevention and enhancing patient safety. We describe our experience of using FMEA as a prospective risk-management technique in radiation oncology at a national network of oncology hospitals in the United States, capitalizing not only on the use of a team-based tool but also creating momentum across a network of collaborative facilities seeking to learn from and share best practices with each other. The major steps of our analysis across 4 sites and collectively were: choosing the process and subprocesses to be studied, assembling a multidisciplinary team at each site responsible for conducting the hazard analysis, and developing and implementing actions related to our findings. We identified 5 areas of performance improvement for which risk-reducing actions were successfully implemented across our enterprise.

  19. Heat Transfer and Failure Mode Analyses of Ultrahigh-Temperature Ceramic Thermal Protection System of Hypersonic Vehicles

    Directory of Open Access Journals (Sweden)

    Tianbao Cheng

    2014-01-01

    Full Text Available The transient temperature distribution of the ultrahigh-temperature ceramic (UHTC thermal protection system (TPS of hypersonic vehicles is calculated using finite volume method. Convective cooling enables a balance of heat increment and loss to be achieved. The temperature in the UHTC plate at the balance is approximately proportional to the surface heat flux and is approximately inversely proportional to the convective heat transfer coefficient. The failure modes of the UHTCs are presented by investigating the thermal stress field of the UHTC TPS under different thermal environments. The UHTCs which act as the thermal protection materials of hypersonic vehicles can fail because of the tensile stress at the lower surface, an area above the middle plane, and the upper surface as well as because of the compressive stress at the upper surface. However, the area between the lower surface and the middle plane and a small area near the upper surface are relatively safe. Neither the compressive stress nor the tensile stress will cause failure of these areas.

  20. Modeling Freedom From Progression for Standard-Risk Medulloblastoma: A Mathematical Tumor Control Model With Multiple Modes of Failure

    Energy Technology Data Exchange (ETDEWEB)

    Brodin, N. Patrik, E-mail: nils.patrik.brodin@rh.dk [Radiation Medicine Research Center, Department of Radiation Oncology, Rigshospitalet, Copenhagen (Denmark); Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Vogelius, Ivan R. [Radiation Medicine Research Center, Department of Radiation Oncology, Rigshospitalet, Copenhagen (Denmark); Björk-Eriksson, Thomas [Department of Oncology, Skåne University Hospital and Lund University, Lund (Sweden); Munck af Rosenschöld, Per [Radiation Medicine Research Center, Department of Radiation Oncology, Rigshospitalet, Copenhagen (Denmark); Niels Bohr Institute, University of Copenhagen, Copenhagen (Denmark); Bentzen, Søren M. [Radiation Medicine Research Center, Department of Radiation Oncology, Rigshospitalet, Copenhagen (Denmark); Department of Human Oncology, University of Wisconsin Medical School, Madison, Wisconsin (United States)

    2013-10-01

    Purpose: As pediatric medulloblastoma (MB) is a relatively rare disease, it is important to extract the maximum information from trials and cohort studies. Here, a framework was developed for modeling tumor control with multiple modes of failure and time-to-progression for standard-risk MB, using published pattern of failure data. Methods and Materials: Outcome data for standard-risk MB published after 1990 with pattern of relapse information were used to fit a tumor control dose-response model addressing failures in both the high-dose boost volume and the elective craniospinal volume. Estimates of 5-year event-free survival from 2 large randomized MB trials were used to model the time-to-progression distribution. Uncertainty in freedom from progression (FFP) was estimated by Monte Carlo sampling over the statistical uncertainty in input data. Results: The estimated 5-year FFP (95% confidence intervals [CI]) for craniospinal doses of 15, 18, 24, and 36 Gy while maintaining 54 Gy to the posterior fossa was 77% (95% CI, 70%-81%), 78% (95% CI, 73%-81%), 79% (95% CI, 76%-82%), and 80% (95% CI, 77%-84%) respectively. The uncertainty in FFP was considerably larger for craniospinal doses below 18 Gy, reflecting the lack of data in the lower dose range. Conclusions: Estimates of tumor control and time-to-progression for standard-risk MB provides a data-driven setting for hypothesis generation or power calculations for prospective trials, taking the uncertainties into account. The presented methods can also be applied to incorporate further risk-stratification for example based on molecular biomarkers, when the necessary data become available.

  1. 铸造铝合金镦粗挤压铆接接头失效形式和强度的分析%Analysis on failure modes and strength for upset protrusion riveted joints of casting aluminum alloy

    Institute of Scientific and Technical Information of China (English)

    李渭佳; 杨连发

    2016-01-01

    Upset protrusion riveting method was used to join castings. The performance of joint obtained by the method upsetting-extrusion was analyzed based on the failure modes and strength. The various testing schemes were obtained through orthogonal test method by chan-ging diameters and depths of the punch. Furthermore, based on the principle of constant volume, rivet heights under different test schemes were calculated, and the upset protrusion riveting tests were carried out. Then, it was conducted the shearing and tensile tests of parts. According to the results, the failure modes were analyzed and the failure limit diagram of joints was obtained. At last, the effects of the geometrical dimensions of the punch on the shear strength and tensile strength of joints were studied. The results show that the tensile strength of joints is lower than the shear strength;joints occur to shearing failure on tail under the shear loading. However, joints occur to head peeling, head shearing and joint pulling failure on tail under the tensile loading.%镦粗挤压铆接是针对铸造件的连接提出的一种铆接技术,从失效形式和强度两个方面对镦粗挤压铆接得到的接头性能进行分析,通过改变冲头直径和深度,采用正交试验,得到不同的试验组合。基于体积不变原理,计算出各个试验组合下需要的铆钉高度,进行镦粗挤压铆接试验,对铆接得到的试件进行剪切和拉伸试验。根据试验结果,分析接头的失效形式,并且绘制出接头的失效极限图,最后分析了冲头尺寸对接头抗剪强度和抗拉强度的影响。研究结果表明:采用镦粗挤压铆接方法得到的接头,其抗剪强度高于抗拉强度;剪切载荷下,接头只发生根部剪断失效;拉伸载荷下,接头发生头部剥离、头部剪断和铆钉根部拉断失效。

  2. Failure modes in high-power lithium-ion batteries for use inhybrid electric vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Kostecki, R.; Zhang, X.; Ross Jr., P.N.; Kong, F.; Sloop, S.; Kerr, J.B.; Striebel, K.; Cairns, E.; McLarnon, F.

    2001-06-22

    The Advanced Technology Development (ATD) Program seeks to aid the development of high-power lithium-ion batteries for hybrid electric vehicles. Nine 18650-size ATD baseline cells were tested under a variety of conditions. The cells consisted of a carbon anode, LiNi{sub 0.8}Co{sub 0.2}O{sub 2} cathode and DEC-EC-LiPF{sub 6} electrolyte, and they were engineered for high-power applications. Selected instrumental techniques such as synchrotron IR microscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, gas chromatography, etc. were used to characterize the anode, cathode, current collectors and electrolyte from these cells. The goal was to identify detrimental processes which lead to battery failure under a high-current cycling regime as well as during storage at elevated temperatures. The diagnostic results suggest that the following factors contribute to the cell power loss: (a) SEI deterioration and non-uniformity on the anode, (b) morphology changes, increase of impedance and phase separation on the cathode, (c) pitting corrosion on the cathode Al current collector, and (d) decomposition of the LiPF{sub 6} salt in the electrolyte at elevated temperature.

  3. Survival and failure modes: platform-switching for internal and external hexagon cemented fixed dental prostheses.

    Science.gov (United States)

    Anchieta, Rodolfo B; Machado, Lucas S; Hirata, Ronaldo; Coelho, Paulo G; Bonfante, Estevam A

    2016-10-01

    This study evaluated the probability of survival (reliability) of platform-switched fixed dental prostheses (FDPs) cemented on different implant-abutment connection designs. Eighty-four-three-unit FDPs (molar pontic) were cemented on abutments connected to two implants of external or internal hexagon connection. Four groups (n = 21 each) were established: external hexagon connection and regular platform (ERC); external hexagon connection and switched platform (ESC); internal hexagon and regular platform (IRC); and internal hexagon and switched platform (ISC). Prostheses were subjected to step-stress accelerated life testing in water. Weibull curves and probability of survival for a mission of 100,000 cycles at 400 N (two-sided 90% CI) were calculated. The beta values of 0.22, 0.48, 0.50, and 1.25 for groups ERC, ESC, IRC, and ISC, respectively, indicated a limited role of fatigue in damage accumulation, except for group ISC. Survival decreased for both platform-switched groups (ESC: 74%, and ISC: 59%) compared with the regular matching platform counterparts (ERC: 95%, and IRC: 98%). Characteristic strength was higher only for ERC compared with ESC, but not different between internal connections. Failures chiefly involved the abutment screw. Platform switching decreased the probability of survival of FDPs on both external and internal connections. The absence in loss of characteristic strength observed in internal hexagon connections favor their use compared with platform-switched external hexagon connections. © 2016 Eur J Oral Sci.

  4. Hydrogen in Ti and Zr alloys: industrial perspective, failure modes and mechanistic understanding

    Science.gov (United States)

    Chapman, T. P.; Dye, D.; Rugg, D.

    2017-06-01

    Titanium is widely used in demanding applications, such as in aerospace. Its strength-to-weight ratio and corrosion resistance make it well suited to highly stressed rotating components. Zirconium has a no less critical application where its low neutron capture cross section and good corrosion resistance in hot water and steam make it well suited to reactor core use, including fuel cladding and structures. The similar metallurgical behaviour of these alloy systems makes it alluring to compare and contrast their behaviour. This is rarely undertaken, mostly because the industrial and academic communities studying these alloys have little overlap. The similarities with respect to hydrogen are remarkable, albeit potentially unsurprising, and so this paper aims to provide an overview of the role hydrogen has to play through the material life cycle. This includes the relationship between alloy design and manufacturing process windows, the role of hydrogen in degradation and failure mechanisms and some of the underpinning metallurgy. The potential role of some advanced experimental and modelling techniques will also be explored to give a tentative view of potential for advances in this field in the next decade or so. This article is part of the themed issue 'The challenges of hydrogen and metals'.

  5. Black and solder joint fracture failure mode of ENIG PCB%黑盘与化镍金PCB焊点失效模式

    Institute of Scientific and Technical Information of China (English)

    李伏; 李斌

    2013-01-01

      文章通过多个化镍金PCB焊接失效案例,探讨了黑盘与化镍金PCB焊点失效模式之间的关系。%This article explores the relationship between the black pad with Electroless Nickel Immersion Gold PCB solder joint failure mode through multiple nickel gold PCB soldering failure cases.

  6. Failure mechanism analysis of a discrete 650V enhancement mode GaN-on-Si power device with reverse conduction accelerated power cycling test

    DEFF Research Database (Denmark)

    Song, Sungyoung; Munk-Nielsen, Stig; Uhrenfeldt, Christian

    2017-01-01

    A commercial discrete enhancement mode gallium nitride power component employing advanced package technology without conventional bond wire possesses the ability for bidirectional conduction. The gallium nitride power components can provide not only higher forward conductivity but also superior r...... of cycles to failure. In physical failure analysis, delamination of a solder joint between a chip and a copper layer of an aluminum print circuit board is observed with a scanning acoustic microscope....

  7. Spatial and Temporal Mode-Of-Failure Transitions in Faulted Earth Materials: A Link Between Mechanics and Hydrology

    Science.gov (United States)

    Goodwin, L. B.; Wilson, J. E.; Rawling, G. C.; Tobin, H.; Mozley, P. S.; Wilson, J. L.

    2002-12-01

    Research into fluid-fault interactions generally falls into two categories: 1) work that considers fault impacts on fluid flow (typically based on static conceptual models of fault-zone architecture) and 2) studies that address fluid impacts on fault-zone mechanics (in which dynamic mechanical processes are considered in detail but the hydrology of the fault-protolith system is not quantified). Bridging the gap between these end-member approaches, and considering dynamic fluid-rock interactions, requires consideration of three-dimensional spatial and temporal variations in fault-zone character, and their resulting impact on both the hydrology and mechanics of fault-protolith systems. We argue that understanding how spatial and temporal mode-of-failure transitions are controlled by the evolving petrophysical characteristics of both protolith and fault rock is a key part of this analysis. Examples of spatial transitions in faulted ignimbrites (Los Alamos, NM and Nevada Test Site, NV) and temporal transitions in faulted sedimentary sequences (Sand Hill fault zone, NM and San Gregorio fault, CA) illustrate this point. In all cases, the primary control on mode of failure at a given location and time appears to be the strength and number of contacts between clasts in the faulted material. Contact area increases with increasing consolidation (which increases with overburden and by particulate flow in a fault zone), cementation (a record of fluid-rock interaction), and welding, and is inversely proportional to porosity. In the weakest, highest porosity materials, failure is accomplished by particulate flow with minor cataclasis. With increasing contact area, sand and non-welded tuff fail through formation of deformation bands. In the strongest materials (fully lithified sedimentary rock and welded tuff), the rocks fail by fracture. The 3-D distribution of structures within a given fault zone will therefore reflect the petrophysical features of the geomaterials intersected

  8. 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.

  9. Design of a Programmable System for Failure Modes and Effect Analysis of Steam-Power Plant Based on the Fault Tree Analysis

    Directory of Open Access Journals (Sweden)

    Dr. Zuhair I. Ahmad Al- Dauod

    2005-01-01

    Full Text Available In this paper, the system of the power plant has been investigated as a special type of industrial systems, which has a significant role in improving societies since the electrical energy has entered all kinds of industries, and it is considered as the artery of modern life. The aim of this research is to construct a programming system, which could be used to identify the most important failure modes that are occur in a steam type of power plants. Also the effects and reasons of each failure mode could be analyzed through the usage of this programming system reaching to the basic events (main reasons that causing each failure mode. The construction of this system for FMEA is depending on the logical relationships of the fault tree analysis for the systems that contained in the power station. The designing of such system could be used as an assistance tool for the specialist user (the power engineer in identifying of all reasons and effects for any type of failures. So this is help to fastening the repairing operation of the identified failure mode to improve the efficiency of operating system as represented by the maintainability, which is a function of system reliability. The selection of the steam type of power generation systems for the application of this study, because this type is the most common type of Iraqi power plants. While such the designed system could be programmed to be use in another types of industrial systems.

  10. 空空导弹冗余系统共模失效%Approach of Common Mode Failure Analysis in Redundant System of Air-to-Air Missile

    Institute of Scientific and Technical Information of China (English)

    王丽丽; 周光巍; 王俊华

    2011-01-01

    为避免空空导弹冗余系统产生共模失效,提高产品可靠性和安全性。在研究共模失效分析方法的基础上,结合空空导弹的研制特点,对某型空空导弹电源组件点火电路冗余系统共模故障进行了定性分析,识别了点火电路中的共模故障,分析了故障原因和耦合因素,并提出了相应的改进措施。%In order to avoiding common mode failure of the air-to-air missile, and improving the reliability and safety of the product, combine the developing character of the air-to-air missile, made a qualitative a- nalysis of the common mode failure in the redundant system of a type air-to-air missile power supply module igniting circuit based on the study of the method of common mode failure analysis, identified the com- mon mode failure of the equipment, analyzed the cause of failure and the coupling factor, put forward improvement measures.

  11. First-principle and data-driven model- based approach in rotating machinery failure mode detection

    Directory of Open Access Journals (Sweden)

    G. Wszołek

    2010-12-01

    Full Text Available Purpose: A major concern of modern diagnostics is the use of vibration or acoustic signals generated by a machine to reveal its operating conditions. This paper presents a method which allows to periodically obtain estimates of model eigenvalues represented by complex numbers. The method is intended to diagnose rotating machinery under transient conditions.Design/methodology/approach: The method uses a parametric data-driven model, the parameters of which are estimated using operational data.Findings: Experimental results were obtained with the use of a laboratory single-disc rotor system equipped with both sliding and hydrodynamic bearings. The test rig used allows measurements of data under normal, or reference, and malfunctioning operation, including oil instabilities, rub, looseness and unbalance, to be collected.Research limitations/implications: Numerical and experimental studies performed in order to validate the method are presented in the paper. Moreover, literature and industrial case studies are analyzed to better understand vibration modes of the rotor under abnormal operating conditions. Practical implications: A model of the test rig has been developed to verify the method proposed herein and to understand the results of the experiments. Hardware realization of the proposed method was implemented as a standalone operating module developed using the Texas Instruments TMS3200LF2407 Starter Kit.Originality/value: The parametric approach was proposed instead of nonparametric one towards diagnosing of rotating machinery.

  12. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-01-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using limit load based analytical model and micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 materials examined. The critical fusion zone size for nugget pullout shall be derived for individual materials based on different base metal properties as well as different heat affected zone (HAZ) and weld properties resulted from different welding parameters.

  13. Effects of Fusion Zone Size on Failure Modes and Performance of Advanced High Strength Steel Spot Welds (2006-01-0531)

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-03-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using the limit load based analytical model and the micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied using statistical data analysis tools. The results in this study show that the conventional weld size of 4 t1/2 can not produce nugget pullout mode for both the DP800 and TRIP800 materials. The results also suggest that performance based spot weld acceptance criteria should be developed for different AHSS spot welds.

  14. Influence of preparation design and ceramic thicknesses on fracture resistance and failure modes of premolar partial coverage restorations.

    Science.gov (United States)

    Guess, Petra C; Schultheis, Stefan; Wolkewitz, Martin; Zhang, Yu; Strub, Joerg R

    2013-10-01

    Preparation designs and ceramic thicknesses are key factors for the long-term success of minimally invasive premolar partial coverage restorations. However, only limited information is presently available on this topic. The purpose of this in vitro study was to evaluate the fracture resistance and failure modes of ceramic premolar partial coverage restorations with different preparation designs and ceramic thicknesses. Caries-free human premolars (n=144) were divided into 9 groups. Palatal onlay preparation comprised reduction of the palatal cusp by 2 mm (Palatal Onlay Standard), 1 mm (Palatal-Onlay-Thin), or 0.5 mm (Palatal Onlay Ultrathin). Complete-coverage onlay preparation additionally included the buccal cusp (Occlusal Onlay Standard; Occlusal Onlay Thin; Occlusal Onlay Ultrathin). Labial surface preparations with chamfer reductions of 0.8 mm (Complete-Veneer-Standard), 0.6 mm (Complete-Veneer-Thin), and 0.4 mm (Complete Veneer Ultrathin) were implemented for complete veneer restorations. Restorations were fabricated from a pressable lithium disilicate ceramic (IPS-e.max-Press) and cemented adhesively (Syntac-Classic/Variolink-II). All specimens were subjected to cyclic mechanical loading (F=49 N, 1.2 million cycles) and simultaneous thermocycling (5°C to 55°C) in a mouth-motion simulator. After fatigue, restorations were exposed to single-load-to-failure. Two-way ANOVA was used to identify statistical differences. Pair-wise differences were calculated and P-values were adjusted by the Tukey-Kramer method (α=.05). All specimens survived fatigue. Mean (SD) load to failure values (N) were as follows: 837 (320/Palatal-Onlay-Standard), 1055 (369/Palatal-Onlay-Thin), 1192 (342/Palatal-Onlay-Ultrathin), 963 (405/Occlusal-Onlay-Standard), 1108 (340/Occlusal-Onlay-Thin), 997 (331/Occlusal-Onlay-Ultrathin), 1361 (333/Complete-Veneer-Standard), 1087 (251/Complete-Veneer-Thin), 883 (311/Complete-Veneer-Ultrathin). Palatal-onlay restorations revealed a significantly

  15. Evaluation of failure modes of computerized planning phase of interstitial implants with high dose rate brachytherapy using HFMEA; Avaliacao dos modos de falha do planejamento computadorizado em implantes intersticiais com braquiterapia de alta taxa de dose usando HFMEA

    Energy Technology Data Exchange (ETDEWEB)

    Biazotto, Bruna; Tokarski, Marcio, E-mail: bruna@ceb.unicamp.br [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Engenharia Biomedica

    2014-08-15

    This paper evaluates the failure modes of the computerized planning step in interstitial implants with high dose rate brachytherapy. The prospective tool of risk management Health Care Failure Mode and Effects Analysis (HFMEA) was used. Twelve subprocesses were identified, and 33 failure modes of which 21 justified new safety actions, and 9 of them were intolerable risks. The method proved itself useful in identifying failure modes, but laborious and subjective in their assessment. The main risks were due to human factors, which require training and commitment of management to their mitigation. (author)

  16. Use of failure modes and effects analysis in design of the tracker system for the HET wide-field upgrade

    Science.gov (United States)

    Hayes, Richard; Beets, Tim; Beno, Joseph; Booth, John; Cornell, Mark; Good, John; Heisler, James; Hill, Gary; Kriel, Herman; Penney, Charles; Rafal, Marc; Savage, Richard; Soukup, Ian; Worthington, Michael; Zierer, Joseph

    2012-09-01

    In support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), the Center for Electromechanics at The University of Texas at Austin was tasked with developing the new Tracker and control system to support the HETDEX Wide-Field Upgrade. The tracker carries the 3,100 kg Prime Focus Instrument Package and Wide Field Corrector approximately 13 m above the 10 m diameter primary mirror. Its safe and reliable operation by a sophisticated control system, over a 20 year life time is a paramount requirement for the project. To account for all potential failures and potential hazards, to both the equipment and personnel involved, an extensive Failure Modes and Effects Analysis (FMEA) was completed early in the project. This task required participation of all the stakeholders over a multi-day meeting with numerous follow up exchanges. The event drove a number of significant design decisions and requirements that might not have been identified this early in the project without this process. The result is a system that has multiple layers of active and passive safety systems to protect the tens of millions of dollars of hardware involved and the people who operate it. This paper will describe the background of the FMEA process, how it was utilized on HETDEX, the critical outcomes, how the required safety systems were implemented, and how they have worked in operation. It should be of interest to engineers, designers, and managers engaging in complex multi-disciplinary and parallel engineering projects that involve automated hardware and control systems with potentially hazardous operating scenarios.

  17. RISIKO RANTAI PASOK KAKAO DI INDONESIA DENGAN METODE ANALYTIC NETWORK PROCESS DAN FAILURE MODE EFFECT ANALYSIS TERINTEGRASI

    Directory of Open Access Journals (Sweden)

    Harumi Aini

    2015-03-01

    Full Text Available Cocoa is one of the plantation commodities whose role is quite important for the national economy of Indonesia. However, the cocoa industry faces several problems including the various risks involved in the cocoa supply chain. The aim of this study were: 1 Identify the various risks involved in the cocoa supply chain, 2 analyze and evaluate the supply chain actors members with the highest risk in the cocoa supply chain management, and 3 understand how to evaluate and mitigate the highest risk in the cocoa supply chain effectively and efficiently. An Integrated Analytic Network Process (ANP and Weighted Failure Mode Effect Analysis (WFMEA method will be used to determine and analyze the highest risk in the cocoa supply chain. The results of the priority of the members of the value chain in the cocoa supply chain risk management are the farmer (0.408 with the risk of having the greatest priority is production risk (0.221. Risk control could be done by improving the productivity and competitiveness of cocoa.Keywords: ANP, FMEA, cocoa, risk management, supply chainABSTRAKKakao merupakan salah satu komoditas perkebunan yang peranannya cukup penting bagi perekonomian Indonesia. Industri kakao menghadapi beberapa masalah termasuk berbagai risiko yang timbul dalam rantai pasokan kakao. Tujuan penelitian ini adalah 1 mengidentifikasi macam-macam risiko pada rantai pasok kakao, 2 menganalisis dan mengevaluasi anggota pelaku rantai pasok dengan risiko tertinggi dalam manajemen rantai pasok kakao, dan 3 mengetahui cara mengevaluasi dan memitigasi risiko tertinggi pada rantai pasok kakao dengan efektif dan efisien. Metode Analytic Network Process (ANP dan Weighted Failure Mode Effect Analysis (WFMEA terintegrasi digunakan untuk mengetahui dan menganalisis risiko tertinggi dalam rantai pasokan kakao. Hasil prioritas anggota pelaku rantai pasok dalam manajemen risiko rantai pasokan kakao petani (0,408 dengan risiko yang memiliki prioritas terbesar adalah

  18. Usulan Perbaikan Mutu Produk Sarung Tangan dengan Menggunakan Metode Statistical Quality Control (SQC) dan Metode Failure Mode and Effect Analysis (FMEA) pada PT. Medisafe Technologies

    OpenAIRE

    Hasibuan, Ali Abbas

    2016-01-01

    PT. Medisafe Technologies adalah perusahaan yang bergerak dibidang produksi sarung tangan. Permasalahan yang sedang dihadapi PT. Medisafe Technologies adalah kecacatan sarung tangan melebihi batas standar kecacatan yang diinginkan oleh perusahaan yaitu maksimum sebesar 5%. Berdasarkan kondisi tersebut, maka perlu dilakukan penyelesaian terhadap penyebab kecacatan sarung tangan dengan menggunakan Statistical Quality Control (SQC) dengan Seven Tools dan Failure Mode and Effect Analysis (FMEA). ...

  19. The effect of a fiber reinforced cavity configuration on load bearing capacity and failure mode of endodontically treated molars restored with CAD/CAM resin composite overlay restorations

    NARCIS (Netherlands)

    Rocca, G.T.; Saratti, C.M.; Cattani-Lorente, M.; Feilzer, A.J.; Scherrer, S.; Krecji, I.

    2015-01-01

    Objectives To evaluate the fracture strength and the mode of failure of endodontically treated molars restored with CAD/CAM overlays with fiber reinforced composite build-up of the pulp chamber. Methods 40 Devitalized molars were cut over the CEJ and divided into five groups (n = 8). The pulp chambe

  20. Effects of the tool rotational speed and shoulder penetration depth on mechanical properties and failure modes of friction stir spot welds of aluminum 2024-T3 sheets

    Energy Technology Data Exchange (ETDEWEB)

    Paidar, Moslem; Khodabandeh, Alireza; Najafi, Hamidreza [Islamic Azad University, Tehran (Iran, Islamic Republic of); Roughaghdam, Alireza Sabour [Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2014-12-15

    In this work, friction stir spot welding with 1.6 mm thickness of the 2024-T3 aluminum alloy is carried out. The effects of the tool rotational speed and shoulder penetration depth on surface appearance, macrostructure, temperature profile, maximum failure load and failure modes are investigated. Results show that, the effect of the tool rotational speed on maximum tensile shear load is similar to the effect of the shoulder penetration depth, increasing tool rotational speed and shoulder penetration depth resulted in the increase of the tensile shear load. Maximum load of about 8282 N is obtained by using 1000 rpm rotational speed and 0.7 mm shoulder penetration depth. Observation of the failed specimens indicates two types of failure modes under tensile shear loading, the shear fracture that occurs in low shoulder penetration depths and tensile shear fracture that occurs in high shoulder penetration depths.

  1. Analysis of failure in patients with adenoid cystic carcinoma of the head and neck an international collaborative study

    DEFF Research Database (Denmark)

    Amit, Moran; Binenbaum, Yoav; Sharma, Kanika

    2014-01-01

    BACKGROUND Adenoid cystic carcinoma (ACC) is a locally aggressive tumor with a high prevalence of distant metastases. The current study aimed to identify independent predictors of outcome and to characterize the patterns of failure. METHODS: An international retrospective review of 489 ACC patients...

  2. Investigation on the Mechanism and Failure Mode of Laser Transmission Spot Welding Using PMMA Material for the Automotive Industry.

    Science.gov (United States)

    Wang, Xiao; Liu, Baoguang; Liu, Wei; Zhong, Xuejiao; Jiang, Yingjie; Liu, Huixia

    2017-01-01

    To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA) is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s) and type II (pulse frequency and the duration is 5 Hz, 3 s)) to the welding quality was investigated. The result showed that, in the case of the same peak voltages and defocusing distances, the number of bubbles for type I was obviously more than type II. The failure mode of type I was the base plate fracture along the solder joint, and the connection strength of type I was greater than type II. The weld pool diameter:depth ratio for type I was significantly greater than type II. It could be seen that there was a certain relationship between the weld pool diameter:depth ratio and the welding strength. By the finite element simulation, the weld pool for type I was more slender than type II, which was approximately the same as the experimental results.

  3. Investigation on the Mechanism and Failure Mode of Laser Transmission Spot Welding Using PMMA Material for the Automotive Industry

    Directory of Open Access Journals (Sweden)

    Xiao Wang

    2017-01-01

    Full Text Available To satisfy the need of polymer connection in lightweight automobiles, a study on laser transmission spot welding using polymethyl methacrylate (PMMA is conducted by using an Nd:YAG pulse laser. The influence of three variables, namely peak voltages, defocusing distances and the welding type (type I (pulse frequency and the duration is 25 Hz, 0.6 s and type II (pulse frequency and the duration is 5 Hz, 3 s to the welding quality was investigated. The result showed that, in the case of the same peak voltages and defocusing distances, the number of bubbles for type I was obviously more than type II. The failure mode of type I was the base plate fracture along the solder joint, and the connection strength of type I was greater than type II. The weld pool diameter:depth ratio for type I was significantly greater than type II. It could be seen that there was a certain relationship between the weld pool diameter:depth ratio and the welding strength. By the finite element simulation, the weld pool for type I was more slender than type II, which was approximately the same as the experimental results.

  4. Failure mode and effects analysis in designing a virtual reality-based training simulator for bilateral sagittal split osteotomy.

    Science.gov (United States)

    Sofronia, R E; Knott, T; Davidescu, A; Savii, G G; Kuhlen, T; Gerressen, M

    2013-03-01

    Virtual reality-based simulators offer a cost-effective and efficient alternative to traditional medical training and planning. Developing a simulator that enables the training of medical skills and also supports recognition of errors made by the trainee is a challenge. The first step in developing such a system consists of error identification in the real procedure, in order to ensure that the training environment covers the most significant errors that can occur. This paper focuses on identifying the main system requirements for an interactive simulator for training bilateral sagittal split osteotomy (BSSO). An approach is proposed based on failure mode and effects analysis (FMEA), a risk analysis method that is well structured and already an approved technique in other domains. Based on the FMEA results, a BSSO training simulator is currently being developed, which centres upon the main critical steps of the procedure (sawing and splitting) and their main errors. FMEA seems to be a suitable tool in the design phase of developing medical simulators. Herein, it serves as a communication medium for knowledge transfer between the medical experts and the system developers. The method encourages a reflective process and allows identification of the most important elements and scenarios that need to be trained. Copyright © 2013 John Wiley & Sons, Ltd.

  5. Risiko Kegagalan pada Kualitas Produksi Air Minum Isi Ulang di Kecamatan Sukolilo Surabaya Menggunakan Failure Mode and Effect Analysis (FMEA

    Directory of Open Access Journals (Sweden)

    Egy Asri Yassin Utami

    2017-01-01

    Full Text Available Kebutuhan manusia terhadap air minum yang layak konsumsi semakin lama semakin berkembang sebanding dengan perkembangan penduduk yang kian lama kian meningkat. Untuk dapat memenuhi kebutuhan air minum sehari-hari, banyak industri yang membuka usaha air minum diantaranya adalah adanya depot air minum isi ulang (DAMIU. Pemilihan depot air minum isi ulang sebagai alternatif air minum menjadi risiko yang dapat membahayakan kesehatan jika kualitas depot air minum isi ulang masih diragukan. Penilitian ini menggunakan metode FMEA (Failure Mode and Effect Analysis untuk mencari prioritas terjadinya kegagalan dalam proses pengolahan air minum isi ulang. Risiko-risiko yang didapat harus memiliki nilai agar terukur sehingga ditemukan prioritas penanganan dan dicari upaya untuk perbaikan. Penilaian tersebut dikenal dengan nilai RPN (Risk Priority Number yaitu hasil pengalian dari tingkat keparahan (severity, frekuensi kejadian (occurrence dan tingkat deteksi (detection. Berdasarkan hasil analisa dan identifikasi menggunakan metode FMEA diketahui bahwa kegagalan yang terjadi pada sistem UV dengan 3 prioritas tertinggi yaitu penggunaan UV dengan nilai RPN 100, waktu kontak UV dengan nilai RPN 100 dan penggantian filter awal dengan nilai RPN 64. Pada sistem UV dan ozon, 3 prioritas tertinggi yaitu waktu kontak sistem ozon, waktu kontak UV dan penggunaan UV dengan masing-masing nilai RPN yaitu 100. Sedangkan pada sistem UV, ozon dan RO (Reverse Osmosis 3 prioritas tertinggi sama seperti dengan sistem UV dan ozon dengan nilai RPN yang berbeda yaitu lama pengoperasian dengan nilai 100, waktu kontak dan kesesuaian penggunaan UV dengan nilai 64.

  6. Incomplete excision of non-melanoma skin cancer of the head and neck: can we predict failure?

    DEFF Research Database (Denmark)

    Kjerkegaard, Ulrik Knap; Stolle, Lars Bjørn

    2014-01-01

    Background Reported incomplete excision rates vary widely. This study described a single center's treatment of basal cell carcinoma (BCC) and squamous cell carcinomas (SCC) of the head and neck and investigated possible causes of incomplete excision. Methods All excised BCCs and SCCs in 2011 were...... cases. Four significant factors were identified to predict incomplete excision, including age >75 years (relative risk (RR) = 14.8 % (95 %-CI: 5.8–24.7 %)), BCC tumor size above 1.5 cm (RR = 17.1 % (95 %-CI: 3.7–28.7 %)), lack of sufficient excision margin in SCC (....1–36.9 %)) and lack of frozen sectioning in high-risk areas (RR = 16.9 % (95 %-CI: 7.5–27.2 %)). Neither gender, tumor type, histological subtype, biopsy prior to surgery, tumor location nor surgeon grade predicted incomplete excision. Conclusions Head and neck BCCs, and SCCs are difficult to treat, and the need...

  7. ANALISA PENENTUAN FAKTOR DOMINAN KEGAGALAN DESAIN KOMPONEN SEAT ASS’Y OIL FILTER DENGAN METODE FMEA (FAILUR MODE AND EFFECTS ANALYSIS DI PT. SELAMAT SEMPURNA TBK

    Directory of Open Access Journals (Sweden)

    Dimas Novrizal

    2013-10-01

    Full Text Available Filter oli terdiri dari berbagai macam komponen dan beberapa diantaranya adalah seat, elco  dan  seat  assy.  Kadangkalanya komponen-komponen tersebt  mengalami kegagalan desain. Dari bermacam-macam bentuk kegagalan yang berasal dari klaim pelanggan yang terangkum dalam Rekaman Klaim Pelanggan, ada yang memerlukan perhatian serius. Yaitu potensi kegagalan yang dominan. Untu mengetahui klaim yang dominan terhadap (potensial failure, dilakukan analisa terhadap bermacam-macam kegagalan yang ada.Kegagalan- kegagalam tersebut yang pada awalnya berbentuk kasus, ditransformasikan kedalam bentuk angka/nilai, yang  mana  nilai-nilai tersebut adalah sebuah standar  yang  telah  ditetapkan didalam Referensi Manual Potential Failure Mode and Efects Analysis (Chrysler Corporation, Ford Motor Company, General Motor Corporation. Dari nilai-nilai yang telah ditetapkan, yaitu nilai Detection serta nilai severity yang diperoleh dari brainstorming serta pengalaman team, serta nilai occurance yang diperoleh dari penghitungan nilai PPM yang kesemua Potensi kegagalan tersebut ditransformasikan kedalam Possible failure Rates, didapat nilai RPN. Nilai RPN itu adalah hasil perkalian dari ketiga unsur diatas. RPN yang telah dibuat listnya menggambarkan bahwa RPN dengan nilai 192, Potensial Failure Mode; Tinggi titik emboss tidak seragam, menduduki peringkat tertinggi. Meskipun demikian, Potential Failure yang lainpun juga perlu ditindak lanjuti sesuai hasil analisanya, yang mana perbaikan dilakukan dengan skala prioritas, dari RPN tertinggi ke RPN terendah. 

  8. Improvement of the safety of a clinical process using failure mode and effects analysis: Prevention of venous thromboembolic disease in critical patients.

    Science.gov (United States)

    Viejo Moreno, R; Sánchez-Izquierdo Riera, J Á; Molano Álvarez, E; Barea Mendoza, J A; Temprano Vázquez, S; Díaz Castellano, L; Montejo González, J C

    2016-11-01

    To improve critical patient safety in the prevention of venous thromboembolic disease, using failure mode and effects analysis as safety tool. A contemporaneous cohort study covering the period January 2014-March 2015 was made in 4 phases: phase 1) prior to failure mode and effects analysis; phase 2) conduction of mode analysis and implementation of the detected improvements; phase 3) evaluation of outcomes, and phase 4) (post-checklist introduction impact. Patients admitted to the adult polyvalent ICU of a third-level hospital center. A total of 196 patients, older than 18 years, without thromboembolic disease upon admission to the ICU and with no prior anticoagulant treatment. A series of interventions were implemented following mode analysis: training, and introduction of a protocol and checklist to increase preventive measures in relation to thromboembolic disease. Indication and prescription of venous thrombosis prevention measures before and after introduction of the measures derived from the failure mode and effects analysis. A total of 59, 97 and 40 patients were included in phase 1, 3 and 4, respectively, with an analysis of the percentage of subjects who received thromboprophylaxis. The failure mode and effects analysis was used to detect potential errors associated to a lack of training and protocols referred to thromboembolic disease. An awareness-enhancing campaign was developed, with staff training and the adoption of a protocol for the prevention of venous thromboembolic disease. The prescription of preventive measures increased in the phase 3 group (91.7 vs. 71.2%, P=.001). In the post-checklist group, prophylaxis was prescribed in 97.5% of the patients, with an increase in the indication of dual prophylactic measures (4.7, 6.7 and 41%; P<.05). There were no differences in complications rate associated to the increase in prophylactic measures. The failure mode and effects analysis allowed us to identify improvements in the prevention of

  9. Environmental risk assessment of low density polyethylene unit using the method of failure mode and effect analysis

    Directory of Open Access Journals (Sweden)

    Salati Parinaz

    2012-01-01

    Full Text Available The ninth olefin plan of Arya Sasol Petrochemical Company (A.S.P.C. is regarded the largest gas Olefin Unit located on Pars Special Economic Energy Zone (P.S.E.E.Z. Considering the importance of the petrochemical unit, its environmental assessment seems necessary to identify and reduce potential hazards. For this purpose, after determining the scope of the study area, identification and measurement of the environmental parameters, environmental risk assessment of the unit was carried out using Environment Failure Mode and Effect Analysis (EFMEA. Using the noted method, sources causing environmental risks were identified, rated and prioritized. Beside, the impacts of the environmental aspects derived from the unit activities as well as their consequences were also analyzed. Furthermore, the identified impacts were prioritized based on Risk Priority Number (RPN and severity level of the consequences imposed on the affected environment. After performing statistical calculations, it was found that the environmental aspects owing the risk priority number higher than 15 have a high level of risk. Results obtained from Low Density Polyethylene Unit revealed that the highest risk belongs to the emergency vent system with risk priority number equal to 48. It is occurred due to imperfect performance of the reactor safety system leading to the emissions of ethylene gas, particles, and radioactive steam as well as air and noise pollutions. Results derived from secondary assessment of the environmental aspects, through difference in calculated RPN and activities risk levels showed that employing modern methods and risk assessment are have remarkably reduced the severity of risk and consequently detracted the damages and losses incurred on the environment.

  10. Prediction of Short-Term Outcome in Acute Superior Vestibular Nerve Failure: Three-Dimensional Video-Head-Impulse Test and Caloric Irrigation

    Directory of Open Access Journals (Sweden)

    Holger A. Rambold

    2015-01-01

    Full Text Available This retrospective study examines acute unilateral vestibular failure (up to seven days after onset with modern vestibular testing (caloric irrigation and video-head-impulse test, vHIT in 54 patients in order to test if the short-term outcome of the patients depends on the lesion pattern defined by the two tests. Patients were grouped according to a pathological unilateral caloric weakness without a pathological vHIT: group I; additional a pathological vHIT of the lateral semicircular canal (SCC: group II; and an additional pathological vHIT of the anterior SCC: group III. Patients with involvement of the posterior SCC were less frequent and not included in the analysis. Basic parameters, such as age of the subjects, days after symptom onset, gender, side of the lesion, treatment, and dizziness handicap inventory, were not different in groups I to III. The frequency of pathological clinical findings and pathological quantified measurements increased from groups I to III. The outcome parameter “days spent in the hospital” was significantly higher in group III compared to group I. The analysis shows that differential vestibular testing predicts short-term outcome of the patients and might be in future important to treat and coach patients with vestibular failure.

  11. Skin Cancer of the Head and Neck with Perineural Invasion: Defining the Clinical Target Volumes Based on the Pattern of Failure

    Science.gov (United States)

    Gluck, Iris; Ibrahim, Mohannad; Popovtzer, Aron; Teknos, Theodoros N.; Chepeha, Douglas B; Prince, Mark E; Moyer, Jeffrey S; Bradford, Carol R; Eisbruch, Avraham

    2009-01-01

    Purpose To analyze patterns of failure in patients with head and neck cutaneous squamous cell carcinoma (HNCSCC) and clinical/radiological evidence of perineural invasion (CPNI), in order to define neural clinical target volume (CTV) for treatment planning. Methods Patients treated with 3D conformal or intensity modulated radiotherapy (IMRT) for HNCSCC with CPNI were included in the study. A retrospective review of the clinical charts, radiotherapy (RT) plans and radiological studies has been conducted. Results Eleven consecutive patients with HNCSCCs with CPNI were treated from 2000 through 2007. Most patients received multiple surgical procedures and RT courses. The most prevalent failure pattern was along cranial nerves (CNs), and multiple CNs were ultimately involved in the majority of cases. In all cases the involved CNs at recurrence were the main nerves innervating the primary tumor sites, as well as their major communicating nerves. We have found several distinct patterns of disease spread along specific CNs depending on the skin regions harboring the primary tumors, including multiple branches of CN V and VII. These patterns and the pertinent anatomy are detailed in the paper. Conclusions Predictable disease spread patterns along cranial nerves supplying the primary tumor sites were found in this study. Awareness of these patterns, as well as knowledge of the relevant cranial nerve anatomy, should be the basis for CTV definition and delineation for RT treatment planning. PMID:18938044

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

    Science.gov (United States)

    Varzakas, Theodoros H; Arvanitoyannis, Ioannis S

    2007-01-01

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

  13. 组件架构系统的失效模式和影响分析%Failure mode and effect analysis of component architecture system

    Institute of Scientific and Technical Information of China (English)

    鲁守荣

    2016-01-01

    文章对安全性分析技术失效模式和影响分析(Failure Mode and Effect Analysis,FMEA)在组件架构系统中的应用和处理进行了研究.基于组件构造系统的特点和FMEA方法,构造了基于消息序列图确定FMEA的失效模式.

  14. Recognising and referring children exposed to domestic abuse: a multi-professional, proactive systems-based evaluation using a modified Failure Mode and Effects Analysis (FMEA).

    Science.gov (United States)

    Ashley, Laura; Armitage, Gerry; Taylor, Julie

    2017-03-01

    Failure Modes and Effects Analysis (FMEA) is a prospective quality assurance methodology increasingly used in healthcare, which identifies potential vulnerabilities in complex, high-risk processes and generates remedial actions. We aimed, for the first time, to apply FMEA in a social care context to evaluate the process for recognising and referring children exposed to domestic abuse within one Midlands city safeguarding area in England. A multidisciplinary, multi-agency team of 10 front-line professionals undertook the FMEA, using a modified methodology, over seven group meetings. The FMEA included mapping out the process under evaluation to identify its component steps, identifying failure modes (potential errors) and possible causes for each step and generating corrective actions. In this article, we report the output from the FMEA, including illustrative examples of the failure modes and corrective actions generated. We also present an analysis of feedback from the FMEA team and provide future recommendations for the use of FMEA in appraising social care processes and practice. Although challenging, the FMEA was unequivocally valuable for team members and generated a significant number of corrective actions locally for the safeguarding board to consider in its response to children exposed to domestic abuse.

  15. TP53 disruptive mutations lead to head and neck cancer treatment failure through inhibition of radiation-induced senescence.

    Science.gov (United States)

    Skinner, Heath D; Sandulache, Vlad C; Ow, Thomas J; Meyn, Raymond E; Yordy, John S; Beadle, Beth M; Fitzgerald, Alison L; Giri, Uma; Ang, K Kian; Myers, Jeffrey N

    2012-01-01

    Mortality of patients with head and neck squamous cell carcinoma (HNSCC) is primarily driven by tumor cell radioresistance leading to locoregional recurrence (LRR). In this study, we use a classification of TP53 mutation (disruptive vs. nondisruptive) and examine impact on clinical outcomes and radiation sensitivity. Seventy-four patients with HNSCC treated with surgery and postoperative radiation and 38 HNSCC cell lines were assembled; for each, TP53 was sequenced and the in vitro radioresistance measured using clonogenic assays. p53 protein expression was inhibited using short hairpin RNA (shRNA) and overexpressed using a retrovirus. Radiation-induced apoptosis, mitotic cell death, senescence, and reactive oxygen species (ROS) assays were carried out. The effect of the drug metformin on overcoming mutant p53-associated radiation resistance was examined in vitro as well as in vivo, using an orthotopic xenograft model. Mutant TP53 alone was not predictive of LRR; however, disruptive TP53 mutation strongly predicted LRR (P = 0.03). Cell lines with disruptive mutations were significantly more radioresistant (P disruptive TP53 mutations significantly decreased radiation-induced senescence, as measured by SA-β-gal staining, p21 expression, and release of ROS. The mitochondrial agent metformin potentiated the effects of radiation in the presence of a disruptive TP53 mutation partially via senescence. Examination of our patient cohort showed that LRR was decreased in patients taking metformin. Disruptive TP53 mutations in HNSCC tumors predicts for LRR, because of increased radioresistance via the inhibition of senescence. Metformin can serve as a radiosensitizer for HNSCC with disruptive TP53, presaging the possibility of personalizing HNSCC treatment. © 2011 AACR.

  16. Utilization of Failure Mode and Effects Analysis (FMEA Method in Increasing the Revenue of Emergency Department; a Prospective Cohort Study

    Directory of Open Access Journals (Sweden)

    Ali Shahrami

    2013-12-01

    Full Text Available Introduction: The balance between revenue and cost of an organization/system is essential to maintain its survival and quality of services. Emergency departments (ED are one of the most important parts of health care delivery system. Financial discipline of EDs, by increasing the efficiency and profitability, can directly affect the quality of care and subsequently patient satisfaction. Accordingly, the present study attempts to investigate failure mode and effects analysis (FMEA method in identifying the problems leading to the loss of ED revenue and offer solutions to help fix these problems. Methods: This prospective cohort study investigated the financial records of ED patients and evaluated the effective errors in reducing the revenue in ED of Imam Hossein hospital, Tehran, Iran, from October 2007 to November 2009. The whole department was divided based on FMEA into one main system and six subsystems. The study was divided in two phases. In the first phase, the problems leading to the loss in the revenue in each subsystem were identified and weighted to four groups using risk priority number (RPN, and the solutions for fixing them were planned. Then, at the second phase discovered defects in the first phase were fixed according to their priority. Finally, the impact of each solution was compared before and after interventions using the repeated measure ANOVA test. Results: At last, 100 financial records of ED patients were evaluated during the first phase of the study. The average of ED revenue in the six months of the first phase was 73.1±3.65 thousands US dollar/month. 12 types of errors were detected in the predefined subsystems. ED revenue rose from 73.1 to 153.1, 207.06, 240, and 320 thousands US dollar/month after solving of first, second, third, and fourth priority problems, respectively (337.75% increase in two years (p<0.001. 111.0% increase in the ED revenue after solving of first priority problems reveals that they were

  17. Utilization of Failure Mode and Effects Analysis (FMEA Method in Increasing the Revenue of Emergency Department; a Prospective Cohort Study

    Directory of Open Access Journals (Sweden)

    Ali Shahrami

    2015-05-01

    Full Text Available Introduction: The balance between revenue and cost of an organization/system is essential to maintain its survival and quality of services. Emergency departments (ED are one of the most important parts of health care delivery system. Financial discipline of EDs, by increasing the efficiency and profitability, can directly affect the quality of care and subsequently patient satisfaction. Accordingly, the present study attempts to investigate failure mode and effects analysis (FMEA method in identifying the problems leading to the loss of ED revenue and offer solutions to help fix these problems. Methods: This prospective cohort study investigated the financial records of ED patients and evaluated the effective errors in reducing the revenue in ED of Imam Hossein hospital, Tehran, Iran, from October 2007 to November 2009. The whole department was divided based on FMEA into one main system and six subsystems. The study was divided in two phases. In the first phase, the problems leading to the loss in the revenue in each subsystem were identified and weighted to four groups using risk priority number (RPN, and the solutions for fixing them were planned. Then, at the second phase discovered defects in the first phase were fixed according to their priority. Finally, the impact of each solution was compared before and after interventions using the repeated measure ANOVA test. Results: At last, 100 financial records of ED patients were evaluated during the first phase of the study. The average of ED revenue in the six months of the first phase was 73.1±3.65 thousands US dollar/month. 12 types of errors were detected in the predefined subsystems. ED revenue rose from 73.1 to 153.1, 207.06, 240, and 320 thousands US dollar/month after solving of first, second, third, and fourth priority problems, respectively (337.75% increase in two years (p<0.001. 111.0% increase in the ED revenue after solving of first priority problems reveals that they were

  18. Administrative risk quantification of subcutaneous and intravenous therapies in Italian centers utilizing the Failure Mode and Effects Analysis approach

    Directory of Open Access Journals (Sweden)

    Ponzetti C

    2016-08-01

    Full Text Available Clemente Ponzetti,1 Monica Canciani,2 Massimo Farina,2 Sara Era,3 Stefan Walzer4,5 1Gruppo Policlinico di Monza, Alessandria, ANMDO National Association of Hospital Physicians, Bologna, 2Studio EmmEffe Srl, Milan, 3Roche Spa, Monza, Italy; 4MArS Market Access & Pricing Strategy GmbH, Weil am Rhein, 5State University Baden-Wuerttemberg, Health Care Management, Loerrach, Germany Background: In oncology, an important parameter of safety is the potential treatment error in hospitals. The analyzed hypothesis is that of subcutaneous therapies would provide a superior safety benefit over intravenous therapies through fixed-dose administrations, when analyzed with trastuzumab and rituximab.Methods: For the calculation of risk levels, the Failure Mode and Effect Analysis approach was applied. Within this approach, the critical treatment path is followed and risk classification for each individual step is estimated. For oncology and hematology administration, 35 different risk steps were assessed. The study was executed in 17 hematology and 16 breast cancer centers in Italy. As intravenous and subcutaneous were the only injection routes in medical available for trastuzumab and rituximab in oncology at the time of the study, these two therapies were chosen.Results: When the risk classes were calculated, eight high-risk areas were identified for the administration of an intravenous therapy in hematology or oncology; 13 areas would be defined as having a median-risk classification and 14 areas as having a low-risk classification (total risk areas: n=35. When the new subcutaneous formulation would be applied, 23 different risk levels could be completely eliminated (65% reduction. Important high-risk classes such as dose calculation, preparation and package labeling, preparation of the access to the vein, pump infusion preparation, and infusion monitoring were included in the eliminations. The overall risk level for the intravenous administration was estimated

  19. Palliative radiotherapy in locally advanced head and neck cancer after failure of induction chemotherapy: Comparison of two fractionation schemes

    Directory of Open Access Journals (Sweden)

    Kailash Chandra Pandey

    2013-01-01

    Full Text Available Context: Among patients with locally advanced head and neck squamous cell cancers (LAHNSCC, the prognosis after nonresponse or progression despite induction chemotherapy (IC is dismal, and further treatment is often palliative in intent. Given that nonresponse to chemotherapy could indicate subsequent radioresistance, we intended to assess the outcomes with two different fractionation schemes. Aims: To compare the outcomes of two fractionation schemes- ′standard′ (consisting 3GyX5 daily fractions for 2 consecutive weeks versus ′hybrid′ (6GyX3 fractions on alternate days during the 1 st week, followed by 2GyX5 daily fractions in the 2 nd week. Settings and Design: Prospective randomized controlled two-arm unblinded trial. Materials and Methods: Patients with locally advanced oropharyngeal, laryngeal, and hypopharyngeal cancers treated with a minimum of two cycles of taxane, platinum, and fluorouracil-based IC were eligible if residual disease volume amounted >30 cm 3 . Kaplan-Meier survival curves were compared by the log-rank test. Response rates were compared using the unpaired t-test. Quality of life (QOL was measured via patient reported questionnaires. Results: Of the initially enrolled 51 patients, 45 patients (24 from standard arm, and 21 from the hybrid arm were eligible for analysis. Despite being underpowered to attain statistical significance, there still seemed to be a trend towards improvement in progression-free (Hazard ratio (HR for progression: 0.5966; 95% CI 0.3216-1.1066 and overall survival (HR for death: 0.6062; 95% CI 0.2676-1.3734 with the hybrid arm when compared to the standard arm. Benefits were also observed with regards to response rates and QOL. Rate of complications were similar in both arms. Conclusions: In comparison to the routinely used palliative fractionation scheme of 30 Gray (Gy in 10 fractions (Fr, the use of hybrid fractionation which integrates hypofractionation in the 1 st week, followed by

  20. The Pattern of Failure after Re-Irradiation of Recurrent Squamous Cell Head and Neck Cancer: Implications for Defining the Targets

    Science.gov (United States)

    Popovtzer, Aron; Gluck, Iris; Chepeha, Douglas B; Teknos, Theodoros N; Moyer, Jeffrey S; Prince, Mark E; Bradford, Carol R; Eisbruch, Avraham

    2009-01-01

    Purpose Re-irradiation (re-RT) of recurrent head and neck cancer (HNC) may achieve long term disease control in some patients, at the expense of high rates of late sequelae. Limiting the re-RT targets to the recurrent gross tumor volume (rGTV) would reduce the volumes of re-irradiated tissues, however, its effect on tumor recurrence pattern is unknown. Methods Retrospective review of 66 patients who underwent curative-intent re-RT for non-resectable recurrent or second primary mucosal squamous cell HNC. Treatment was delivered with 3-dimensional conformal (3D) RT or intensity modulated RT (IMRT). The targets in all patients consisted of the rGTVs with tight (0.5 cm) margins, with no intent to treat prophylactically lymph nodes or sub-clinical disease in the vicinity of the rGTVs. The sites of local-regional failures (LRFs) were determined using imaging at the time of failure, and were compared to the rGTVs. Results Median re-RT dose was 68 Gy. 47 patients (71%) received concomitant chemotherapy and 31 (47%) received hyperfractionated, accelerated RT. At a median follow up 42 month, 16 (23%) are alive and free of disease. Fifty patients (77%) had a third recurrence or persistent disease, including 47 LRFs. All LRFs occurred within the rGTVs except for two (4%) (95% C.I. 0; 11 %). Nineteen patients (29%) had grade ≥3 late complications, mostly dysphagia (12 patients). Conclusion Almost all LRFs occurred within the re-irradiated rGTVs despite avoiding prophylactic RT of tissue at risk of subclinical disease. These results support confining the re-RT targets to the rGTVs to reduce re-irradiated tissue volumes. PMID:19135312

  1. 某型手榴弹故障模式及影响分析研究%Research on Failure Mode and Analysis of Grenade

    Institute of Scientific and Technical Information of China (English)

    成云; 赵晓利; 仲伟君; 杨岩峰

    2016-01-01

    The grenade is one of the most important infantry weapons. But several accidents have happened when the troops store and use the grenade. The paper has introduced the structure and principle of the grenade. The failure mode and effect analysis( FMEA ) is used to obtain all possible failure modes,the causes of failure and the effect of failure,according to the structural features of the grenade. Fault criticality,detection methods and preventive measures are determined. The reasons of security failure and possible weak links are acquired. It lays the foundation of researching quality changing law and evaluating storage reliability of the grenade.%某型手榴弹是我军重要的单兵武器装备之一,但在部队实际储存和使用过程中曾发生多起安全事故,本文介绍了该型手榴弹的结构和作用原理,结合手榴弹的结构特点,利用故障模式及影响分析的方法分析手榴弹所有可能的故障模式、故障原因及对手榴弹的影响,确定了不同故障模式的严酷度等级、故障检测方法和预防措施,找到了系统内造成安全失效的原因和潜在的薄弱环节,为研究手榴弹整体质量变化规律和评估手榴弹储存可靠性奠定了一定的理论基础。

  2. Life Cost Based FMEA Manual: A Step by Step Guide to Carrying Out a Cost-based Failure Modes and Effects Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Rhee, Seung; Spencer, Cherrill; /Stanford U. /SLAC

    2009-01-23

    Failure occurs when one or more of the intended functions of a product are no longer fulfilled to the customer's satisfaction. The most critical product failures are those that escape design reviews and in-house quality inspection and are found by the customer. The product may work for a while until its performance degrades to an unacceptable level or it may have not worked even before customer took possession of the product. The end results of failures which may lead to unsafe conditions or major losses of the main function are rated high in severity. Failure Modes and Effects Analysis (FMEA) is a tool widely used in the automotive, aerospace, and electronics industries to identify, prioritize, and eliminate known potential failures, problems, and errors from systems under design, before the product is released (Stamatis, 1997). Several industrial FMEA standards such as those published by the Society of Automotive Engineers, US Department of Defense, and the Automotive Industry Action Group employ the Risk Priority Number (RPN) to measure risk and severity of failures. The Risk Priority Number (RPN) is a product of 3 indices: Occurrence (O), Severity (S), and Detection (D). In a traditional FMEA process design engineers typically analyze the 'root cause' and 'end-effects' of potential failures in a sub-system or component and assign penalty points through the O, S, D values to each failure. The analysis is organized around categories called failure modes, which link the causes and effects of failures. A few actions are taken upon completing the FMEA worksheet. The RPN column generally will identify the high-risk areas. The idea of performing FMEA is to eliminate or reduce known and potential failures before they reach the customers. Thus, a plan of action must be in place for the next task. Not all failures can be resolved during the product development cycle, thus prioritization of actions must be made within the design group. One

  3. Joint loads resulting in ACL rupture: Effects of age, sex, and body mass on injury load and mode of failure in a mouse model.

    Science.gov (United States)

    Blaker, Carina L; Little, Christopher B; Clarke, Elizabeth C

    2016-09-07

    Anterior cruciate ligament (ACL) tears are a common knee injury with a known but poorly understood association with secondary joint injuries and post-traumatic osteoarthritis (OA). Female sex and age are known risk factors for ACL injury but these variables are rarely explored in mouse models of injury. This study aimed to further characterize a non-surgical ACL injury model to determine its clinical relevance across a wider range of mouse specifications. Cadaveric and anesthetized C57BL/6 mice (9-52 weeks of age) underwent joint loading to investigate the effects of age, sex, and body mass on ACL injury mechanisms. The ACL injury load (whole joint load required to rupture the ACL) was measured from force-displacement data, and mode of failure was assessed using micro-dissection and histology. ACL injury load was found to increase with body mass and age (p mode of ACL failure varied with both age and sex groups. Avulsion fractures (complete or mixed with mid-substance tears) were common in all age groups but the proportion of mixed and mid-substance failures increased with age. Females were more likely than males to have a major avulsion relative to a mid-substance tear (p model. © 2016 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res.

  4. Failure and Degradation Modes of PV modules in a Hot Dry Climate: Results after 4 and 12 years of field exposure

    Science.gov (United States)

    Mallineni, Jaya krishna

    This study evaluates two photovoltaic (PV) power plants based on electrical performance measurements, diode checks, visual inspections and infrared scanning. The purpose of this study is to measure degradation rates of performance parameters (Pmax, Isc, Voc, Vmax, Imax and FF) and to identify the failure modes in a "hot-dry desert" climatic condition along with quantitative determination of safety failure rates and reliability failure rates. The data obtained from this study can be used by module manufacturers in determining the warranty limits of their modules and also by banks, investors, project developers and users in determining appropriate financing or decommissioning models. In addition, the data obtained in this study will be helpful in selecting appropriate accelerated stress tests which would replicate the field failures for the new modules and would predict the lifetime for new PV modules. The study was conducted at two, single axis tracking monocrystalline silicon (c-Si) power plants, Site 3 and Site 4c of Salt River Project (SRP). The Site 3 power plant is located in Glendale, Arizona and the Site 4c power plant is located in Mesa, Arizona both considered a "hot-dry" field condition. The Site 3 power plant has 2,352 modules (named as Model-G) which was rated at 250 kW DC output. The mean and median degradation of these 12 years old modules are 0.95%/year and 0.96%/year, respectively. The major cause of degradation found in Site 3 is due to high series resistance (potentially due to solder-bond thermo-mechanical fatigue) and the failure mode is ribbon-ribbon solder bond failure/breakage. The Site 4c power plant has 1,280 modules (named as Model-H) which provide 243 kW DC output. The mean and median degradation of these 4 years old modules are 0.96%/year and 1%/year, respectively. At Site 4c, practically, none of the module failures are observed. The average soiling loss is 6.9% in Site 3 and 5.5% in Site 4c. The difference in soiling level is attributed

  5. How to apply clinical cases and medical literature in the framework of a modified "failure mode and effects analysis" as a clinical reasoning tool--an illustration using the human biliary system.

    Science.gov (United States)

    Wong, Kam Cheong

    2016-04-06

    Clinicians use various clinical reasoning tools such as Ishikawa diagram to enhance their clinical experience and reasoning skills. Failure mode and effects analysis, which is an engineering methodology in origin, can be modified and applied to provide inputs into an Ishikawa diagram. The human biliary system is used to illustrate a modified failure mode and effects analysis. The anatomical and physiological processes of the biliary system are reviewed. Failure is defined as an abnormality caused by infective, inflammatory, obstructive, malignancy, autoimmune and other pathological processes. The potential failures, their effect(s), main clinical features, and investigation that can help a clinician to diagnose at each anatomical part and physiological process are reviewed and documented in a modified failure mode and effects analysis table. Relevant medical and surgical cases are retrieved from the medical literature and weaved into the table. A total of 80 clinical cases which are relevant to the modified failure mode and effects analysis for the human biliary system have been reviewed and weaved into a designated table. The table is the backbone and framework for further expansion. Reviewing and updating the table is an iterative and continual process. The relevant clinical features in the modified failure mode and effects analysis are then extracted and included in the relevant Ishikawa diagram. This article illustrates an application of engineering methodology in medicine, and it sows the seeds of potential cross-pollination between engineering and medicine. Establishing a modified failure mode and effects analysis can be a teamwork project or self-directed learning process, or a mix of both. Modified failure mode and effects analysis can be deployed to obtain inputs for an Ishikawa diagram which in turn can be used to enhance clinical experiences and clinical reasoning skills for clinicians, medical educators, and students.

  6. 电机转子失效模式分析%On the Motor Armature Failure Mode Analysis

    Institute of Scientific and Technical Information of China (English)

    李军毓; 蒲瑜

    2013-01-01

    In the test and use of power tools, it’s very common to see the motor armature failure phenomenon of commutator shorted, winding burned, electrical corrosion, shaft broken when the electromechanical energy transforms. This article analyses the causes of various failure phenomenon, preventing and reducing the incidence of potential failure.%在电动工具的测试和使用中,机电能量转换时换向器短路、线圈烧毁、电气腐蚀、轴断裂等电机转子失效现象较为常见。分析各类失效现象的产生原因,避免和减少潜在失效的发生。

  7. Reliability Evaluation of Monolithic Vertical Wall Breakwaters Considering Impulsive Wave Breaking Forces and Failure Modes of the Foundation

    DEFF Research Database (Denmark)

    Burcharth, H. F.; Sørensen, Jørgen S.; Christiani, E.

    1994-01-01

    Impulsive wave breaking forces on a vertical caisson breakwater has been included by Takahashi et al, (1994) in Goda's wave pressure formula (Goda et al. 1972 and Goda 1974). Based on these formulae a deterministic design method following the Japanese recommendations has been used for the design ...... stability analysis is presented by the example of a rotation slip failure involving kinematically correct slip surfaces and failure zones in undrained clay. A conventional static quasi-static analysis based on equating external and internal work is used....

  8. Arrival by ambulance in acute heart failure: insights into the mode of presentation from Acute Studies of Nesiritide in Decompensated Heart Failure (ASCEND-HF).

    Science.gov (United States)

    Ezekowitz, Justin A; Podder, Mohua; Hernandez, Adrian F; Armstrong, Paul W; Starling, Randall C; O'Connor, Christopher M; Califf, Robert M

    2016-03-17

    Limited data exist assessing the relationship between ambulance versus self-presentation and outcomes in patients with acute heart failure (AHF). Clinical trial sites in North America. 1068 patients enrolled in the Acute Studies of Nesiritide in Decompensated Heart Failure (ASCEND-HF) trial. The association between ambulance use and dyspnoea improvement, 30-day mortality or HF rehospitalisation and 180-day mortality. Of the 1068 patients in the substudy, 832 (78%) self-presented (SP) and 236 (22%) patients presented via ambulance. Patients presenting via ambulance were older, more likely to be female, have a higher ejection fraction but similar natriuretic peptide levels as patients who SP. Patients presenting by ambulance (compared with SP) trended towards more dyspnoea improvement at 6 (p=0.09) and 24 h (p=0.10). The co-primary end point (30-day mortality or HF rehospitalisation) was similar between groups (ambulance 12.2% vs SP 11.4%, p=0.74). Patients who presented by ambulance had a higher 30-day and 180-day mortality rate than those who SP (30-day: 4.3% vs 2.2%, p=0.08; 180-day: 15.1% vs 10.3%, p=0.04). After adjustment for baseline characteristics, patients arriving by ambulance (compared with SP) had a 2-fold high risk of 30-day mortality (OR 2.12, 95% CI 0.94 to 4.79), but no relationship to the composite of 30-day mortality/HF rehospitalisation (OR 1.01, 95% CI 0.63 to 1.63). Among patients with AHF, 30-day and 180-day mortality is 1.5-2 times higher for those with presenting via ambulance compared with patients who self-present. Understanding patient-related and system-related factors of ambulance use for patients with AHF is important. NCT00475852. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  9. Application of ISO22000, failure mode, and effect analysis (FMEA) cause and effect diagrams and pareto in conjunction with HACCP and risk assessment for processing of pastry products.

    Science.gov (United States)

    Varzakas, Theodoros H

    2011-09-01

    The Failure Mode and Effect Analysis (FMEA) model has been applied for the risk assessment of pastry processing. A tentative approach of FMEA application to the pastry industry was attempted in conjunction with ISO22000. Preliminary Hazard Analysis was used to analyze and predict the occurring failure modes in a food chain system (pastry processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram, and fishbone diagram). In this work a comparison of ISO22000 analysis with HACCP is carried out over pastry processing and packaging. However, the main emphasis was put on the quantification of risk assessment by determining the Risk Priority Number (RPN) per identified processing hazard. Storage of raw materials and storage of final products at -18°C followed by freezing were the processes identified as the ones with the highest RPN (225, 225, and 144 respectively) and corrective actions were undertaken. Following the application of corrective actions, a second calculation of RPN values was carried out leading to considerably lower values (below the upper acceptable limit of 130). It is noteworthy that the application of Ishikawa (Cause and Effect or Tree diagram) led to converging results thus corroborating the validity of conclusions derived from risk assessment and FMEA. Therefore, the incorporation of FMEA analysis within the ISO22000 system of a pastry processing industry is considered imperative.

  10. Application of Failure Mode and Effect Analysis (FMEA) and cause and effect analysis in conjunction with ISO 22000 to a snails (Helix aspersa) processing plant; A case study.

    Science.gov (United States)

    Arvanitoyannis, Ioannis S; Varzakas, Theodoros H

    2009-08-01

    Failure Mode and Effect Analysis (FMEA) has been applied for the risk assessment of snails manufacturing. A tentative approach of FMEA application to the snails industry was attempted in conjunction with ISO 22000. Preliminary Hazard Analysis was used to analyze and predict the occurring failure modes in a food chain system (snails processing plant), based on the functions, characteristics, and/or interactions of the ingredients or the processes, upon which the system depends. Critical Control points have been identified and implemented in the cause and effect diagram (also known as Ishikawa, tree diagram, and fishbone diagram). In this work a comparison of ISO22000 analysis with HACCP is carried out over snails processing and packaging. However, the main emphasis was put on the quantification of risk assessment by determining the RPN per identified processing hazard. Sterilization of tins, bioaccumulation of heavy metals, packaging of shells and poisonous mushrooms, were the processes identified as the ones with the highest RPN (280, 240, 147, 144, respectively) and corrective actions were undertaken. Following the application of corrective actions, a second calculation of RPN values was carried out leading to considerably lower values (below the upper acceptable limit of 130). It is noteworthy that the application of Ishikawa (Cause and Effect or Tree diagram) led to converging results thus corroborating the validity of conclusions derived from risk assessment and FMEA. Therefore, the incorporation of FMEA analysis within the ISO22000 system of a snails processing industry is considered imperative.

  11. Improved Re-Configurable Sliding Mode Controller for Reusable Launch Vehicle of Second Generation Addressing Aerodynamic Surface Failures and Thrust Deficiencies

    Science.gov (United States)

    Shtessel, Yuri B.

    2002-01-01

    In this report we present a time-varying sliding mode control (TV-SMC) technique for reusable launch vehicle (RLV) attitude control in ascent and entry flight phases. In ascent flight the guidance commands Euler roll, pitch and yaw angles, and in entry flight it commands the aerodynamic angles of bank, attack and sideslip. The controller employs a body rate inner loop and the attitude outer loop, which are separated in time-scale by the singular perturbation principle. The novelty of the TVSMC is that both the sliding surface and the boundary layer dynamics can be varied in real time using the PD-eigenvalue assignment technique. This salient feature is used to cope with control command saturation and integrator windup in the presence of severe disturbance or control effector failure, which enhances the robustness and fault tolerance of the controller. The TV-SMC is developed and tuned up for the X-33 sub-orbital technology demonstration vehicle in launch and re-entry modes. A variety of nominal, dispersion and failure scenarios have tested via high fidelity 6DOF simulations using MAVERIC/SLIM simulation software.

  12. Study Of The Risks Arising From Natural Disasters And Hazards On Urban And Intercity Motorways By Using Failure Mode Effect Analysis (FMEA) Methods

    Science.gov (United States)

    DELİCE, Yavuz

    2015-04-01

    Highways, Located in the city and intercity locations are generally prone to many kind of natural disaster risks. Natural hazards and disasters that may occur firstly from highway project making to construction and operation stages and later during the implementation of highway maintenance and repair stages have to be taken into consideration. And assessment of risks that may occur against adverse situations is very important in terms of project design, construction, operation maintenance and repair costs. Making hazard and natural disaster risk analysis is largely depending on the definition of the likelihood of the probable hazards on the highways. However, assets at risk , and the impacts of the events must be examined and to be rated in their own. With the realization of these activities, intended improvements against natural hazards and disasters will be made with the utilization of Failure Mode Effects Analysis (FMEA) method and their effects will be analyzed with further works. FMEA, is a useful method to identify the failure mode and effects depending on the type of failure rate effects priorities and finding the most optimum economic and effective solution. Although relevant measures being taken for the identified risks by this analysis method , it may also provide some information for some public institutions about the nature of these risks when required. Thus, the necessary measures will have been taken in advance in the city and intercity highways. Many hazards and natural disasters are taken into account in risk assessments. The most important of these dangers can be listed as follows; • Natural disasters 1. Meteorological based natural disasters (floods, severe storms, tropical storms, winter storms, avalanches, etc.). 2. Geological based natural disasters (earthquakes, tsunamis, landslides, subsidence, sinkholes, etc) • Human originated disasters 1. Transport accidents (traffic accidents), originating from the road surface defects (icing

  13. Lightning observation on 77 KV transmission lines and survey on their failure modes. 77kV sodensen no kaminari kansoku to kosho yoso no chosa

    Energy Technology Data Exchange (ETDEWEB)

    Katsuragi, Y.; Kato, K.; Yokotani, M. (Chubu Electric Power Co. Inc., Nagoya (Japan))

    1991-11-01

    It was intended to investigate comprehensively lightning arrestors to prevent two-line power failure due to lightning on a transmission line and the optical ground wire (OPGW), which was found lately problematical due to damages. Lightning observations were carried out for three years on lightning damages to the entire 77 kV transmission lines which carry both two items. This paper summarizes the discussions done by Chubu Electric Power Company of Japan on its 77kV Mizunami-Oi line in the Gifu prefectural district. The lightning observing equipment is an air-cored Rogowskii coil, consisted of a personal computer linked to series of processors and CPU buses including a lightning surge memory to catch lightning behaviors. The power supply is a lithium battery with a capacity of 90 AH which is light in weight and portable. The observation cost is as low as (1/20) of the conventional method. The use of the equipment clarified the lightning modes, and the data analyses elucidated the effects of the lightning arrestor, as well as reduced the power failures and determined the correlation of lightnings with lightning current waveforms which cause damages to the OPGW. The utilization of the developed lightning surge memory, the lightning arrestor operation annunciator, and the ground failure indicator resulted in a great deal of success. 5 refs., 20 figs., 15 tabs.

  14. FRACTURE FAILURE MODES ANALYSIS OF BRIDGE CABLES%桥梁缆索特殊断口失效机理分析

    Institute of Scientific and Technical Information of China (English)

    左海宏; 田飞龙

    2012-01-01

    为延长桥梁缆索的使用寿命,必须确定其失效机理.通过调研国内外大量的桥检资料,将现场取回的桥梁缆索钢丝做断口电镜扫描( SEM)后,对缆索钢丝断口的两种特殊类型(阶梯状断口和杯口状断口)进行了失效机理分析.结果表明,阶梯状断口主要是由于腐蚀疲劳所致;在钢丝无明显锈蚀,当外界荷载超过钢丝的极限承载力时出现塑性破坏是导致杯口状断口的主要原因.%To lengthen the service life of bridge cables, its failure modes must be ascertained. According to investigation of bridge-testing data from home and abroad, and fracture analysis of steel wires of bridge cables fetched from testing ground using electron microscope scanning, two special fracture (cascade fracture & cup and cone-shaped fracture) failure modes of steel wires of bridge cables have been analyzed. The results show that cascade fracture mainly arises from corrosion fatigue;the main reason that leads to cup and cone-shaped fracture is plastic failure which is caused when steel wire corrosion is not serious and external load exceeds ultimate load carrying capacity of steel wire.

  15. Real System Failures

    Data.gov (United States)

    National Aeronautics and Space Administration — This resource area contains descriptions of actual electronic systems failure scenarios with an emphasis on the diversity of failure modes and effects that can...

  16. Establishment of design criteria for acceptable failure modes and fail safe considerations for the space shuttle structural system

    Science.gov (United States)

    Westrup, R. W.

    1972-01-01

    Investigations of fatigue life, and safe-life and fail-safe design concepts as applied to space shuttle structure are summarized. The results are evaluated to select recommended structural design criteria to provide assurance that premature failure due to propagation of undetected crack-like defects will not occur during shuttle operational service. The space shuttle booster, GDC configuration B-9U, is selected as the reference vehicle. Structural elements used as basis of detail analyses include wing spar caps, vertical stabilizer skins, crew compartment skin, orbiter support frame, and propellant tank shell structure. Fatigue life analyses of structural elements are performed to define potential problem areas and establish upper limits of operating stresses. Flaw growth analyses are summarized in parametric form over a range of initial flaw types and sizes, operating stresses and service life requirements. Service life of 100 to 500 missions is considered.

  17. Transformer failure and common-mode loss of instrument power at Nine Mile Point Unit 2 on August 13, 1991

    Energy Technology Data Exchange (ETDEWEB)

    1991-10-01

    On August 13, 1991, at Nine Mile Point Unit 2 nuclear power plant, located near Scriba, New York, on Lake Ontario, the main transformer experienced an internal failure that resulted in degraded voltage which caused the simultaneous loss of five uninterruptible power supplies, which in turn caused the loss of several nonsafety systems, including reactor control rod position indication, some reactor power and water indication, control room annunciators, the plant communications system, the plant process computer, and lighting at some locations. The reactor was subsequently brought to a safe shutdown. Following this event, the US Nuclear Regulatory Commission dispatched an Incident Investigation Team to the site to determine what happened, to identify the probable causes, and to make appropriate findings and conclusions. This report describes the incident, the methodology used by the team in its investigation, and presents and the team's findings and conclusions. 59 figs., 14 tabs.

  18. A periodic inspection and replacement policy for systems subject to competing failure modes due to degradation and traumatic events

    Energy Technology Data Exchange (ETDEWEB)

    Huynh, K.T., E-mail: tuan.huynh@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Barros, A., E-mail: anne.barros@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Berenguer, C., E-mail: christophe.berenguer@utt.f [Universite de technologie de Troyes, Institut Charles Delaunay and STMR UMR CNRS 6279-12, rue Marie Curie, BP2060, 10010 Troyes cedex (France); Castro, I.T., E-mail: inmatorres@unex.e [Departamento de Matematicas, Escuela Politecnica, 10071 Caceres (Spain)

    2011-04-15

    This paper deals with the condition-based maintenance of single-unit systems which are subject to the competing and dependent failures due deterioration and traumatic shock events. The main aim is to provide a model to assess the value of condition monitoring information for the maintenance decision-making. A condition-based periodic inspection/replacement policy is developed and compared with a benchmark time-based block replacement policy. Numerical results show that it is indeed useful to follow closely the actual evolution of the system to adapt the maintenance decisions to the true system state to improve the performance of maintenance policies. The analysis of the maintenance costs savings can be used to justify or not the choice to implement a policy based on condition monitoring information and to invest in condition monitoring devices.

  19. Integration of Value Stream Map and Healthcare Failure Mode and Effect Analysis into Six Sigma Methodology to Improve Process of Surgical Specimen Handling

    Directory of Open Access Journals (Sweden)

    Sheng-Hui Hung

    2015-01-01

    Full Text Available Specimen handling is a critical patient safety issue. Problematic handling process, such as misidentification (of patients, surgical site, and specimen counts, specimen loss, or improper specimen preparation can lead to serious patient harms and lawsuits. Value stream map (VSM is a tool used to find out non-value-added works, enhance the quality, and reduce the cost of the studied process. On the other hand, healthcare failure mode and effect analysis (HFMEA is now frequently employed to avoid possible medication errors in healthcare process. Both of them have a goal similar to Six Sigma methodology for process improvement. This study proposes a model that integrates VSM and HFMEA into the framework, which mainly consists of define, measure, analyze, improve, and control (DMAIC, of Six Sigma. A Six Sigma project for improving the process of surgical specimen handling in a hospital was conducted to demonstrate the effectiveness of the proposed model.

  20. Integration of Value Stream Map and Healthcare Failure Mode and Effect Analysis into Six Sigma Methodology to Improve Process of Surgical Specimen Handling.

    Science.gov (United States)

    Hung, Sheng-Hui; Wang, Pa-Chun; Lin, Hung-Chun; Chen, Hung-Ying; Su, Chao-Ton

    2015-01-01

    Specimen handling is a critical patient safety issue. Problematic handling process, such as misidentification (of patients, surgical site, and specimen counts), specimen loss, or improper specimen preparation can lead to serious patient harms and lawsuits. Value stream map (VSM) is a tool used to find out non-value-added works, enhance the quality, and reduce the cost of the studied process. On the other hand, healthcare failure mode and effect analysis (HFMEA) is now frequently employed to avoid possible medication errors in healthcare process. Both of them have a goal similar to Six Sigma methodology for process improvement. This study proposes a model that integrates VSM and HFMEA into the framework, which mainly consists of define, measure, analyze, improve, and control (DMAIC), of Six Sigma. A Six Sigma project for improving the process of surgical specimen handling in a hospital was conducted to demonstrate the effectiveness of the proposed model.

  1. Using Healthcare Failure Mode and Effect Analysis tool to review the process of ordering and administrating potassium chloride and potassium phosphate.

    Science.gov (United States)

    Esmail, Rosmin; Cummings, Cheryl; Dersch, Deonne; Duchscherer, Greg; Glowa, Judy; Liggett, Gail; Hulme, Terrance

    2005-01-01

    During the spring of 2004, in the Calgary Health Region (CHR) two critical incidents occurred involving patients receiving continuous renal replacement therapy (CRRT) in the intensive care unit (ICU). The outcome of these events resulted in the sudden death of both patients. The Department of Critical Care Medicine's Patient Safety and Adverse Events Team (PSAT), utilized the Healthcare Failure Mode and Effect Analysis (HFMEA) tool to review the process and conditions surrounding the ordering and administration of potassium chloride (KCI) and potassium phosphate (KPO4) in our ICUs. The HFMEA tool and the multidisciplinary team structure provided a solid framework for systematic analysis and prioritization of areas for improvement regarding the use of intravenous, high-concentration KCL and KPO4 in the ICU.

  2. Applicability of NASA contract quality management and failure mode effect analysis procedures to the USGS Outer Continental Shelf oil and gas lease management program

    Science.gov (United States)

    Dyer, M. K.; Little, D. G.; Hoard, E. G.; Taylor, A. C.; Campbell, R.

    1972-01-01

    An approach that might be used for determining the applicability of NASA management techniques to benefit almost any type of down-to-earth enterprise is presented. A study was made to determine the following: (1) the practicality of adopting NASA contractual quality management techniques to the U.S. Geological Survey Outer Continental Shelf lease management function; (2) the applicability of failure mode effects analysis to the drilling, production, and delivery systems in use offshore; (3) the impact on industrial offshore operations and onshore management operations required to apply recommended NASA techniques; and (4) the probable changes required in laws or regulations in order to implement recommendations. Several management activities that have been applied to space programs are identified, and their institution for improved management of offshore and onshore oil and gas operations is recommended.

  3. A New Scale for Evaluating the Risks for In-Hospital Falls of Newborn Infants: A Failure Modes and Effects Analysis Study

    Directory of Open Access Journals (Sweden)

    Faruk Abike

    2010-01-01

    Full Text Available We aimed to develop a new scale for evaluating risks and preventive measures for in-hospital falls of newborn infants, from admission to discharge of the expectant mother. Our study was prepared in accordance with Failure Modes and Effects Analysis criteria. The risks and preventive measures for in-hospital falls of newborns were determined. Risk Priority Numbers (RPNs were determined by multiplication of the scores of severity, probability of occurrence, and probability of detection. Analyses showed that risks having the highest RPNs were the mother with epidural anesthesia (RPN: 350 point, holding of the baby at the moment of delivery (RPN: 240, and transportation of baby right after delivery (RPN: 240. A reduction was detected in all RPNs after the application of preventive measures. Our risk model can function as a guide for obstetric clinics that need to form strategies to prevent newborn falls.

  4. Failure Mode and Effects Analysis of CO2 Gas Shield Welding%CO2气保焊的故障模式与影响分析

    Institute of Scientific and Technical Information of China (English)

    王余海

    2012-01-01

    Welding is a main operating process in the manufacturing of pressure vessels for commercial air- conditions. During processing, CO2 gas shield welding is mainly used, especially for fabrication of evaporators and condensers. In the actual production process, leakage faults caused by welding seriously affect the quality of prod- ucts, so it needs to optimize the welding parameters by experimental design method. However, there are. many fac- tors that affect the welds quality, so it is necessary to analyze the failure modes by FMEA before parameters de- sign to make the factors selection more accurate and effective, and pick out the key factors.%焊接是商用空调设备压力容器制造过程中的主要操作工序。CO2气体保护焊主要在蒸发器、冷凝器的装配过程中被使用。在实际生产过程中,焊接造成的故障泄漏严重影响产品质量,需要使用试验设计方法对焊接参数进行优化.但影响焊缝质量的因素众多,在进行参数设计之前,为使因素选择更准确、有效,使用FMEA(failure mode effects analysis)方法对气保焊故障模式进行分析,从中选择出关键因素。

  5. Correction factor determination on failure rate equation of MacLaurin series for low and high mode application

    Directory of Open Access Journals (Sweden)

    Totok R. Biyanto

    2016-06-01

    Full Text Available Safety Instrumented Function (SIF is implemented on the system to prevent hazard in process industry. In general, most of SIF implementation in process industry works in low demand condition. Safety valuation of SIF that works in low demand can be solved by using quantitative method. The quantitative method is a simplified exponential equation form of MacLaurin series, which can be called simplified equation. Simplified equation used in high demand condition will generate a higher Safety Integrity Level (SIL and it will affect the higher safety cost. Therefore, the value of low or high demand rate limit should be determined to prevent it. The result of this research is a first order equation that can fix the error of SIL, which arises from the usage of simplified equation, without looking the demand rate limit for low and high demand. This equation is applied for SIL determination on SIF with 1oo1 vote. The new equation from this research is λ = 0.9428 λMC + 1.062E−04 H/P, with 5% average of error, where λMC is a value of λ from the simplified equation, Hazardous event frequency (H is a probabilistic frequency of hazard event and P is Probability of Failure on Demand (PFD in Independent Protection Layers (IPLs. The equation generated from this research could correct SIL of SIF in various H and P. Therefore, SIL design problem could be solved and it provides an appropriate SIL.

  6. 基于多失效模式的扭簧可靠性优化分析%Optimal Analysis of the Reliability for Torsion Spring Based on Multi-failure Modes

    Institute of Scientific and Technical Information of China (English)

    王梅; 陈国定; 肖勇

    2011-01-01

    基于广义应力-广义强度分布干涉理论和单一失效模式下扭簧可靠性计算模型,建立了多失效模式下扭簧可靠度优化数学模型,采用规格化加权法进行各失效模式影响相同(等失效效应)和有差异(非等失效效应)两种情况下的扭簧可靠度计算.在给定扭簧结构和工况约束条件下,应用提出的计算模型和技术进行了失效模式影响相同和有差异的基于可靠度最大的扭簧结构优化,与非优化结构的扭簧可靠度的比较,以及这两种情况下的扭簧可靠度比较.结果表明,提出的可靠度优化模型和方法是可靠和有效的,对于航天工程中零部件的可靠性优化分析具有很好的借鉴作用.%Based on the general stress-intensity distribution of a broad interference theory and reliability model of a single failure mode, the torsion spring reliability optimization model was established under multi-failure mode. The normalized weighted method was used to solve the torsion spring reliability calculation under equal failure effect mode and unequal failure effect mode. Under given structure and constraint conditions of torsion spring, the best reliability optimization of torsion spring structure was done in the same failure mode (equal failure effect) and different failure mode (unequal failure effect) one using the proposed model and techniques. Under equal failure effect and unequal failure effect, compared with the torsion spring reliability of non-optimized structure, the proposed reliability optimization models and methods proposed are reliable, valid and good reference for the reliability optimization of the spacecraft components.

  7. Ulnar head replacement.

    Science.gov (United States)

    Herbert, Timothy J; van Schoonhoven, Joerg

    2007-03-01

    Recent years have seen an increasing awareness of the anatomical and biomechanical significance of the distal radioulnar joint (DRUJ). With this has come a more critical approach to surgical management of DRUJ disorders and a realization that all forms of "excision arthroplasty" can only restore forearm rotation at the expense of forearm stability. This, in turn, has led to renewed interest in prosthetic replacement of the ulnar head, a procedure that had previously fallen into disrepute because of material failures with early implants, in particular, the Swanson silicone ulnar head replacement. In response to these early failures, a new prosthesis was developed in the early 1990s, using materials designed to withstand the loads across the DRUJ associated with normal functional use of the upper limb. Released onto the market in 1995 (Herbert ulnar head prosthesis), clinical experience during the last 10 years has shown that this prosthesis is able to restore forearm function after ulnar head excision and that the materials (ceramic head and noncemented titanium stem), even with normal use of the limb, are showing no signs of failure in the medium to long term. As experience with the use of an ulnar head prosthesis grows, so does its acceptance as a viable and attractive alternative to more traditional operations, such as the Darrach and Sauve-Kapandji procedures. This article discusses the current indications and contraindications for ulnar head replacement and details the surgical procedure, rehabilitation, and likely outcomes.

  8. SU-E-T-105: An FMEA Survey of Intensity Modulated Radiation Therapy (IMRT) Step and Shoot Dose Delivery Failure Modes

    Energy Technology Data Exchange (ETDEWEB)

    Faught, J Tonigan; Johnson, J; Stingo, F; Kry, S; Court, L; Balter, P; Followill, D [UT MD Anderson Cancer Center, Houston, TX (United States)

    2015-06-15

    Purpose: To assess the perception of TG-142 tolerance level dose delivery failures in IMRT and the application of FMEA process to this specific aspect of IMRT. Methods: An online survey was distributed to medical physicists worldwide that briefly described 11 different failure modes (FMs) covered by basic quality assurance in step- and-shoot IMRT at or near TG-142 tolerance criteria levels. For each FM, respondents estimated the worst case H&N patient percent dose error and FMEA scores for Occurrence, Detectability, and Severity. Demographic data was also collected. Results: 181 individual and three group responses were submitted. 84% were from North America. Most (76%) individual respondents performed at least 80% clinical work and 92% were nationally certified. Respondent medical physics experience ranged from 2.5–45 years (average 18 years). 52% of individual respondents were at least somewhat familiar with FMEA, while 17% were not familiar. Several IMRT techniques, treatment planning systems and linear accelerator manufacturers were represented. All FMs received widely varying scores ranging from 1–10 for occurrence, at least 1–9 for detectability, and at least 1–7 for severity. Ranking FMs by RPN scores also resulted in large variability, with each FM being ranked both most risky (1st ) and least risky (11th) by different respondents. On average MLC modeling had the highest RPN scores. Individual estimated percent dose errors and severity scores positively correlated (p<0.10) for each FM as expected. No universal correlations were found between the demographic information collected and scoring, percent dose errors, or ranking. Conclusion: FMs investigated overall were evaluated as low to medium risk, with average RPNs less than 110. The ranking of 11 FMs was not agreed upon by the community. Large variability in FMEA scoring may be caused by individual interpretation and/or experience, thus reflecting the subjective nature of the FMEA tool.

  9. Mode-of-Failure Transitions in High Porosity Sedimentary and Ignimbrite Deposits, and Implications for Fault-Zone Structure and Architecture

    Science.gov (United States)

    Goodwin, L. B.; Rawling, G. C.; Wilson, J. E.; Tobin, H.

    2001-12-01

    Recent studies have demonstrated that fault-zone deformation processes, and thus structures and fault-zone architecture, vary with the petrophysical properties of the protolith. Factors controlling whether or not open fractures form within a given fault zone are of particular importance to understanding fault-zone impacts on fluid flow. We discuss three examples of mode-of-failure transitions from strike-slip and normal faults in sedimentary and volcanic protoliths. Each example illustrates a mechanism by which porosity was reduced over time, resulting in changes in the mechanical behavior of the faulted material. These temporal variations are recorded by overprinting relationships within fault-zone architectural elements. The Sand Hill normal growth fault cuts poorly lithified sediments of the Rio Grande rift, NM. Architectural elements include a fault core bound by tabular mixed zones, which are in turn bracketed by deformation-band damage zones. The mixed zones have been described in poorly lithified sediments only; they consist of material derived from adjacent beds during slip, which has been disaggregated and tectonically mixed. Structures developed during mixing and particulate flow include foliations defined by compositional bands and aligned grains and attenuated and disarticulated beds. These structures are cut by deformation bands in the footwall mixed zone. We interpret these relationships as recording a transition from bulk particulate flow (in normally consolidated sediment) to localized shear within deformation bands (in overconsolidated sediment) as the footwall of the fault was syntectonically exhumed. Mixed zones are also present in the San Gregorio fault zone, a branch of the San Andreas fault system. The San Gregorio fault was active through sedimentation and lithification of rocks currently exposed along the CA coast. Attenuated and boudinaged beds on the SW side of the fault are cut by fractures and veins. We interpret these features as

  10. 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

  11. 单板计算机的故障模式与机理及影响分析%Failure Modes, Mechanisms and Effects Analysis of Single Board Computers

    Institute of Scientific and Technical Information of China (English)

    夏欣; 谢丽梅; 时钟

    2015-01-01

    Failure Modes, Mechanisms and Effects Analysis ( FMMEA) is a kind of reliability analysis method to study the possible failure modes and failure mechanisms of each component of products, and to identify the effects of various failure modes on the components and functions of productes. The way to implement FMMEA for the Single Board Computer, including defining the system, identifying the potential failure modes, and analyzing the causes, mechanisms and effects of the failure, are introduced in detail. And the finite element analysis has been adopted to carry out the process of FMMEA for the Single Board Computer.Besides, through thermal stress analysis and vibration stress analysis, temperature distribution and vibration modes under different environment are obtained, which are the inputs of physics model of failure. And then the quantitative calculation of single point failure of the Single Board Computer is carried out by using a variety of physics of failure models. Results show that the time to failure ( TTF) of random access memory chip with SOP ( small outline package) is the shortest and the failure is due to solder joint fatigue failure caused by the temperature cycle.It is the weak point of the entire circuit board. Thus solder joint thermal fatigue failure is the main failure mechanism of the Single Board Computer. Therefore, in the implementation process of PHM for the Single Board Computer, the failure condition of this position should be monitored intensively.%故障模式、机理及影响分析((FMMEA)是研究产品的每个组成部分可能存在的故障模式、故障机理并确定各个故障模式对产品组成部分和功能的影响的一种可靠性分析方法。详细介绍了对单板计算机进行FM-MEA的实施过程,包括系统定义,确定潜在的故障模式,分析故障原因、故障机理、故障影响等一系列的过程。对单板计算机进行了有限元建模,并通过热应力分析和振动应力分析

  12. Discussion on Several Failure Modes of Environmental Stress Testing%几种环境应力试验的失效模式探讨

    Institute of Scientific and Technical Information of China (English)

    庄少红

    2013-01-01

      环境应力试验是检验产品质量的重要手段之一,对评价产品质量意义重大。产品使用环境复杂多样,环境温度是影响产品性能不可避免的关键因素。建议采用高温应力、温度循环应力、温度冲击应力三种环境应力进行筛选试验,试验中向产品施加合理的环境应力和电应力。本文对环境应力筛选试验的失效模式进行了讨论。%  Environmental stress testing is one of the important means for testing product quality, which is very significant for product quality evaluation. Products will be used in various environments, so the environment temperature is an inevitable influence on most products. We suggest that high temperature stress, temperature cyclic stress,and temperature shock stress be used for environmental stress screening tests, with proper environment stress and electrical stress applying to the product. This paper discuses the failure modes of environmental stress screening tests.

  13. Safety Management of a Clinical Process Using Failure Mode and Effect Analysis: Continuous Renal Replacement Therapies in Intensive Care Unit Patients.

    Science.gov (United States)

    Sanchez-Izquierdo-Riera, Jose Angel; Molano-Alvarez, Esteban; Saez-de la Fuente, Ignacio; Maynar-Moliner, Javier; Marín-Mateos, Helena; Chacón-Alves, Silvia

    2016-01-01

    The failure mode and effect analysis (FMEA) may improve the safety of the continuous renal replacement therapies (CRRT) in the intensive care unit. We use this tool in three phases: 1) Retrospective observational study. 2) A process FMEA, with implementation of the improvement measures identified. 3) Cohort study after FMEA. We included 54 patients in the pre-FMEA group and 72 patients in the post-FMEA group. Comparing the risks frequencies per patient in both groups, we got less cases of under 24 hours of filter survival time in the post-FMEA group (31 patients 57.4% vs. 21 patients 29.6%; p < 0.05); less patients suffered circuit coagulation with inability to return the blood to the patient (25 patients [46.3%] vs. 16 patients [22.2%]; p < 0.05); 54 patients (100%) versus 5 (6.94%) did not get phosphorus levels monitoring (p < 0.05); in 14 patients (25.9%) versus 0 (0%), the CRRT prescription did not appear on medical orders. As a measure of improvement, we adopt a dynamic dosage management. After the process FMEA, there were several improvements in the management of intensive care unit patients receiving CRRT, and we consider it a useful tool for improving the safety of critically ill patients.

  14. Tools for developing a quality management program: proactive tools (process mapping, value stream mapping, fault tree analysis, and failure mode and effects analysis).

    Science.gov (United States)

    Rath, Frank

    2008-01-01

    This article examines the concepts of quality management (QM) and quality assurance (QA), as well as the current state of QM and QA practices in radiotherapy. A systematic approach incorporating a series of industrial engineering-based tools is proposed, which can be applied in health care organizations proactively to improve process outcomes, reduce risk and/or improve patient safety, improve through-put, and reduce cost. This tool set includes process mapping and process flowcharting, failure modes and effects analysis (FMEA), value stream mapping, and fault tree analysis (FTA). Many health care organizations do not have experience in applying these tools and therefore do not understand how and when to use them. As a result there are many misconceptions about how to use these tools, and they are often incorrectly applied. This article describes these industrial engineering-based tools and also how to use them, when they should be used (and not used), and the intended purposes for their use. In addition the strengths and weaknesses of each of these tools are described, and examples are given to demonstrate the application of these tools in health care settings.

  15. 电磁阀的失效模式及维修策略%Solenoid Valve Failure Mode and Maintenance Strategy

    Institute of Scientific and Technical Information of China (English)

    蒋道福

    2012-01-01

    大亚湾和岭澳核电站使用了很多进口电磁阀.随着服役时间不断增加,大量电磁阀出现了漏气、漏油和生锈等故障现象;对这些故障现象进行分类,并结合相关资料分析了电磁阀的工作原理,总结出电磁阀的失效模式;参考法国电力公司(EDF)的维修方法,提出了大亚湾与岭澳核电站电磁阀的维修策略,对相关核电厂电磁阀的维修具有一定的参考价值.%Many solenoid valves were imported from France for Daya Bay and Ling'Ao nuclear power plants. Some phenomena of leaking air or oil and rustiness occurred in solenoid valves with the serve time increases. All malfunction phenomena were classified, operation principle of the solenoid valve was analyzed in combination with relevant information, and the failure mode was summarized. The maintenance strategy of the solenoid valve for Daya Bay and Ling'Ao nuclear power plants was put forward, with reference to the maintenance methods of EDF. It could be served as reference for solenoid valve maintenance in nuclear power plants of similar kind.

  16. Cube or block. Statistical analysis, historial review, failure mode and behaviour; Cubo o bloque. Ajuste estadistico, analisis historico, modo de fallo y comportamiento

    Energy Technology Data Exchange (ETDEWEB)

    Negro, V.; Varela, O.; Campo, J. M. del; Lopez Gutierrez, J. S.

    2010-07-01

    Many different concrete shapes have been developed as armour units for rubble mound breakwaters. Nearly all are mass concrete construction and can be classified as random placed or regular patterns Placed. the majority of artificial armour unit are placed in two layers and they are massive. they intended to function in a similar way to natural rock (cubes, blocks, antifer cubes,...). More complex armour units were designed to achieve greater stability by obtaining a high degree of interlock (dolosse, accropode, Xbloc, core-loc,...). finally, the third group are the regular pattern placed units with a greater percentage of voids for giving a stronger dissipation of cement hydration (cob, shed, hollow cubes,...), This research deals about the comparison between two massive concrete units, the cubes and the blocks and the analysis of the geometry, the porosity, the construction process and the failure mode. The first stage is the statistical analysis. the scope of it is based on the historical reference of the Spanish Breakwaters with main layer of cubes and blocks (ministry of Public Works, General Directorate of Ports, 1988). (Author) 9 refs.

  17. Study and analysis of failure modes of the electrolytic capacitors and thyristors, applied to the protection system of the LHC (Large Hadron Collider); Etude et analyse des modes de defaillances des condensateurs electrolytiques a l'aluminium et des thyristors: appliquees au systeme de protection du LHC (Large Hadron Collider)

    Energy Technology Data Exchange (ETDEWEB)

    Perisse, F

    2003-07-15

    The study presented in this thesis is a contribution about the analysis of failures modes of electrolytic capacitors and thyristors. The studied components are main elements of the protection system of the superconductive magnets of the LHC. The study of the ageing of the electrolytic capacitors has shown that their reliability is strongly related to their technological characteristic. Evolution of their principal indicator of ageing (ESR) can be modeled according to different laws chosen according to their running mode. It appears that the prediction of failure of these components other than that due to wear can be only statistical taking into account the many causes of failure involving various modes of failure. In order to be able to evaluate influence of the ageing of the electrolytic capacitors on a system, simple models taking into account this parameters as well as the effective temperature of the component are proposed. An acceptable precision taking into account the simplicity of the models is obtained. The study of the thyristors has shown that these components have little drift of parameters in static ageing, on the other hand of many failures by short-circuit were observed. These failures always have a local origin, and are due to defects of the components. The breakdown voltage strongly depends on the quality of the thyristor as well as the technology employed. (author)

  18. Failure Atlas for Rolling Bearings in Wind Turbines

    Energy Technology Data Exchange (ETDEWEB)

    Tallian, T. E.

    2006-01-01

    systems used, and by several indexes. The present Atlas is intended as a supplement to the book. It has the same structure but contains only Plate pages, arranged in chapters, each with a chapter heading page giving a short definition of the failure mode illustrated. Each Plate page is self contained, with images, bearing and application data, and descriptions of the failure mode, the images and the suspected causes. Images are provided in two resolutions: The text page includes 6 by 9 cm images. In addition, high resolution image files are attached, to be retrieved by clicking on their 'push pin' icon. While the material in the present Atlas is self-contained, it is nonetheless a supplement to the book and the complete interpretation of the terse image descriptions and of the system underlying the failure code presupposes familiarity with the book. Since this Atlas is a supplement to the book, its chapter numbering follows that of the book. Not all failure modes covered in the book have been found among the observed wind turbines. For that reason, and because of the omission of introductory matter, the chapter numbers in this Atlas are not a continuous sequence.

  19. Failure Modes in Composite Materials.

    Science.gov (United States)

    1987-05-19

    Derek, An Introduction to Composite Materials , New York: Cambridge University Press, 1981. 12. Jamison, R. D., Mechanical Engineering Department...1978. 19. Tsai, Stephen W., Introduction to Composite Materials , Lancaster, Pennsylvania: Technomic Publishing Company, Inc., 1980. 4,’ * .20. Vernon

  20. Air-Cooled Stack Freeze Tolerance Freeze Failure Modes and Freeze Tolerance Strategies for GenDriveTM Material Handling Application Systems and Stacks Final Scientific Report

    Energy Technology Data Exchange (ETDEWEB)

    Hancock, David, W.

    2012-02-14

    Air-cooled stack technology offers the potential for a simpler system architecture (versus liquid-cooled) for applications below 4 kilowatts. The combined cooling and cathode air allows for a reduction in part count and hence a lower cost solution. However, efficient heat rejection challenges escalate as power and ambient temperature increase. For applications in ambient temperatures below freezing, the air-cooled approach has additional challenges associated with not overcooling the fuel cell stack. The focus of this project was freeze tolerance while maintaining all other stack and system requirements. Through this project, Plug Power advanced the state of the art in technology for air-cooled PEM fuel cell stacks and related GenDrive material handling application fuel cell systems. This was accomplished through a collaborative work plan to improve freeze tolerance and mitigate freeze-thaw effect failure modes within innovative material handling equipment fuel cell systems designed for use in freezer forklift applications. Freeze tolerance remains an area where additional research and understanding can help fuel cells to become commercially viable. This project evaluated both stack level and system level solutions to improve fuel cell stack freeze tolerance. At this time, the most cost effective solutions are at the system level. The freeze mitigation strategies developed over the course of this project could be used to drive fuel cell commercialization. The fuel cell system studied in this project was Plug Power's commercially available GenDrive platform providing battery replacement for equipment in the material handling industry. The fuel cell stacks were Ballard's commercially available FCvelocity 9SSL (9SSL) liquid-cooled PEM fuel cell stack and FCvelocity 1020ACS (Mk1020) air-cooled PEM fuel cell stack.

  1. SU-E-T-128: Applying Failure Modes and Effects Analysis to a Risk-Based Quality Management for Stereotactic Radiosurgery in Brazil

    Energy Technology Data Exchange (ETDEWEB)

    Teixeira, F [comissao nacional de energia nuclear, Rio De Janeiro, RJ (Brazil); Universidade do Estado do Rio de Janeiro, Rio De Janeiro, RJ (Brazil); Almeida, C de [Universidade do Estado do Rio de Janeiro, Rio De Janeiro, RJ (Brazil); Huq, M [University of Pittsburgh Medical Center, Pittsburgh, PA (United States)

    2015-06-15

    Purpose: The goal of the present work was to evaluate the process maps for stereotactic radiosurgery (SRS) treatment at three radiotherapy centers in Brazil and apply the FMEA technique to evaluate similarities and differences, if any, of the hazards and risks associated with these processes. Methods: A team, consisting of professionals from different disciplines and involved in the SRS treatment, was formed at each center. Each team was responsible for the development of the process map, and performance of FMEA and FTA. A facilitator knowledgeable in these techniques led the work at each center. The TG100 recommended scales were used for the evaluation of hazard and severity for each step for the major process “treatment planning”. Results: Hazard index given by the Risk Priority Number (RPN) is found to range from 4–270 for various processes and the severity (S) index is found to range from 1–10. The RPN values > 100 and severity value ≥ 7 were chosen to flag safety improvement interventions. Number of steps with RPN ≥100 were found to be 6, 59 and 45 for the three centers. The corresponding values for S ≥ 7 are 24, 21 and 25 respectively. The range of RPN and S values for each center belong to different process steps and failure modes. Conclusion: These results show that interventions to improve safety is different for each center and it is associated with the skill level of the professional team as well as the technology used to provide radiosurgery treatment. The present study will very likely be a model for implementation of risk-based prospective quality management program for SRS treatment in Brazil where currently there are 28 radiotherapy centers performing SRS. A complete FMEA for SRS for these three radiotherapy centers is currently under development.

  2. FAILURE MODE AND CONSTITUTIVE MODEL OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION AFTER EXPOSURE TO HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Zhenjun He; Yupu Song

    2008-01-01

    An orthotropic constitutive relationship with temperature parameters for plain highstrength high-performance concrete (HSHPC) under biaxial compression is developed. It is based on the experiments performed for characterizing the strength and deformation behavior at two strength levels of HSHPC at 7 different stress ratios including α = σ2 : σ3 = 0.00 : -1, -0.20 : -1, -0.30 : -1, -0.40 : -1, -0.50 : -1, -0.75 : -1, -1.00 : -1, after the exposure to normal and high temperatures of 20, 200, 300, 400, 500 and 600℃, and using a large static-dynamic true triaxial machine. The biaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens, and friction-reducing pads were used consisting of three layers of plastic membrane with glycerine in-between for the compressive loading plane. Based on the experimental results, failure modes of HSHPC specimens were described. The principal static compressive strengths, strains at the peak stress and stress-strain curves were measured; and the influence of the temperature and stress ratios on them was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease dramatically with the increase of temperature. The ratio of the biaxial to its uniaxial compressive strength depends on the stress ratios and brittleness-stiffness of HSHPC after exposure to different temperature levels. Comparison of the stress-strain results obtained from the theoretical model and the experimental data indicates good agreement.

  3. Failure mode effects and criticality analysis of a cooling cycling-water system of a oil refinery%某炼油厂冷却循环水系统故障与危害性分析

    Institute of Scientific and Technical Information of China (English)

    盛况; 李洪海

    2012-01-01

    Based on the failure data of a cooling cycling-water system in a oil refinery which was collected for a year, analyzes the reliability of the system was analyzed using failure mode effects and criticality analysis. According to the characteristic of the system' s structure, the cooling cycling-water system had 19 failure modes and was divided into 7 sub-systems including the water cooling tower sub-system, the heat exchanger sub-system, the fan of water cooling tower sub-system, the water pump sub-system, the pipe sub-system, the valve sub-system, the pipe connecting sub-system. The failure rate of each sub-system was calculated, the failure modes and their failure causes were analysed, and the criticality of each subsystem was calculated. The results indicated that the water pump and the fan of water cooling tower have the highest criticality. The criticality of the heat exchanger was the third highest, whereas its failure rate was the fourth highest. It means that only calculating the failure rate was not e-nough when implement failure analysis, the criticality analysis should be considered as well. Finally, the corresponding measures were proposed to improve the reliability of the cooling cycling-water system, which had an obvious effect after a year's application.%根据采集的某炼油厂一年的冷却循环水系统的故障数据,采用故障模式影响及危害性分析方法对该系统的可靠性进行了分析.由该系统结构特点,划分了水冷塔、换热器、水冷塔风机、水泵、水管、阀门等7个子系统及19种故障模式,统计了各子系统的故障率,分析了系统的故障模式及其故障原因,计算了各子系统的危害度.结果表明水泵及水冷塔风机的危害度最高,换热器的危害度排第三,但其故障率排第四,说明在做故障分析时不能只统计故障率而不进行危害度分析.最后提出了相应的改进措施,经过一年的实际运行,效果明显.

  4. RELIABILITY SENSITIVITY DESIGN FOR MECHANICAL COMPONENTS WITH MULTI-FAILURE MODES%多失效模式机械零部件可靠性灵敏度设计

    Institute of Scientific and Technical Information of China (English)

    张义民; 张旭方; 杨周; 黄贤振

    2009-01-01

    基于应力-强度干涉模型,应用概率摄动法及四阶矩技术,讨论多失效模式下机械零部件可靠性分析问题.利用灵敏度分析的梯度算法,确定各个随机参数对机械零部件可靠性灵敏度.在随机参数前四阶矩已知的情况下,放松对随机参数的分布概型限制,使之更接近于工程实际,从而为多失效模式作用下机械零部件可靠性分析和可靠性设计等方面提供理论依据和方法参考.%The failure criteria of reliability processes, which correspond to first excursion probabilities, are defined in terms of a single output state or system response function. However, for more general cases, failure criteria may be defined in terms of several output states. On the other hand, since most of mechanical components in engineering have common source of excitations, the different failure modes are mutually correlated. So the reliability solution for such mechanical components with failure dependencies has been an interesting and challenging subject. Sensitivity is one of the ways to evaluate the performance of structures when the design variables are under the influences of parametric changes. The reliability sensitivity design of structural responses represents an essential ingredient for gradient-based methods needed in structural reliability analysis, optimization, identification etc.An algorithm is presented for evaluating the analytical sensitivity of reliability for mechanical components with correlated failure modes. In doing so, based on the stress-strength interference model, probability perturbation theory and the fourth-order moments technology are extend to discuss the system reliability with multiple failure modes. The proposed formulation computes the analytical sensitivity gradient of reliability with respect to the random parameters. Then a numerical method for reliability sensitivity analysis is discussed and the effects of design parameters on system reliability are

  5. Reliability Analysis of Metallized Film Pulse Capacitors under Competing Failure Modes Based on Regression Analysis%基于参数回归分析的金属化膜脉冲电容器竞争失效分析

    Institute of Scientific and Technical Information of China (English)

    刘芳; 赵建印; 彭绍雄

    2011-01-01

    The failures of metallized-film capacitor have two modes:traumatic and degradation failures. By analyzing degradation mechanism of metallized-film capacitor, a general model under competing failure modes involving both traumatic and degradation failures is given based on parameter regression analysis, and used to analyze the test data of some capacitors. According to the assessment results, the reliability probability of the capacitors is 0. 7986 for 10 000 shots. This model provides an effective method to assess the reliability of electronic products under competing failures modes.%金属化膜脉冲电容器既有突发型失效又有退化型失效.通过分析金属化膜脉冲电容器的退化失效机理,在假设突发失效与退化失效相关的条件下,给出了基于参数回归分析的电容器竞争失效的一般模型,最后利用该模型对某金属化膜脉冲电容器的试验数据进行可靠性分析.根据评估结论,该电容器打靶10 000发的可靠度为0.798 6.该模型为竞争失效模式下电子产品可靠性评估提供了一种新的有效途径.

  6. Preconditioning and triggering of offshore slope failures and turbidity currents revealed by most detailed monitoring yet at a fjord-head delta

    Science.gov (United States)

    Clare, M. A.; Hughes Clarke, J. E.; Talling, P. J.; Cartigny, M. J. B.; Pratomo, D. G.

    2016-09-01

    Rivers and turbidity currents are the two most important sediment transport processes by volume on Earth. Various hypotheses have been proposed for triggering of turbidity currents offshore from river mouths, including direct plunging of river discharge, delta mouth bar flushing or slope failure caused by low tides and gas expansion, earthquakes and rapid sedimentation. During 2011, 106 turbidity currents were monitored at Squamish Delta, British Columbia. This enables statistical analysis of timing, frequency and triggers. The largest peaks in river discharge did not create hyperpycnal flows. Instead, delayed delta-lip failures occurred 8-11 h after flood peaks, due to cumulative delta top sedimentation and tidally-induced pore pressure changes. Elevated river discharge is thus a significant control on the timing and rate of turbidity currents but not directly due to plunging river water. Elevated river discharge and focusing of river discharge at low tides cause increased sediment transport across the delta-lip, which is the most significant of all controls on flow timing in this setting.

  7. 基于“失效模式-失效机理-分析模型”的电子产品可靠性分析应用%Reliability analysis and application of electronic products based on "failure mode- failure mechanism-analysis model"

    Institute of Scientific and Technical Information of China (English)

    孙晓君

    2012-01-01

    The emphasis of electronic product reliability analysis and assessment is to determine the high-risk links. Based on the analysis consideration of failure mechanism, use the analysis method associated with "components, failure mode, failure mechanism and impact factor", through the physical model and an electronic analysis case, realize the whole process which determined the high-risk links and product reliability, and concludes that failure mechanism analysis is more practical than failure mode analysis at last.%电子产品可靠性分析、评价的重点在于确定其高风险环节。基于充分考量失效机理的分析目的。采用了“元器件-失效模式-失效机理-影响因素”相关联的分析方法,通过相关物理模型和一个电子产品分析案例,实现了利用这一方式确定高风险环节和分析可靠性的全过程,得到了这一方法比采用FMEA等失效模式分析更为实际、准确的结论。

  8. 失效模式与效应分析在降低皮试流程风险中的应用%Effect of failure mode and effects analysis used in the lower risk of skin test process

    Institute of Scientific and Technical Information of China (English)

    李丽琴

    2011-01-01

    Objective: Disscuss how to reduce the risk of skin test process by failure mode and effect analysis and explore.Methods: Select randomly from skin test of 1500 patients which compose control group in 2009, After apply failure mode and effect analysis management mode in 2010 , take a skin test of 1500 patients composition observation group, compared the risk value of skin test process of two groups.Results: The risk value of skin test of the observation group was lower than the control group.And the high risk proportion of observation group which take skin test was lower than the control group.Conclusion: Failure mode and effect analysis management mode can effectively control the skin test process risk.%目的:应用失效模式与效应分析,探讨降低皮试流程的风险.方法:随机选取我院2009年实施皮试的1 500例患者为对照组,2010年应用失效模式与效应分析管理模式后进行皮试的1 500例患者为观察组,对比两组皮试流程的风险值.结果:观察组皮试流程的风险值低于对照组,且观察组皮试存在高风险者的比例低于对照组.结论:失效模式与效应分析管理模式可以有效控制皮试流程风险.

  9. Common Cause Failures and Ultra Reliability

    Science.gov (United States)

    Jones, Harry W.

    2012-01-01

    A common cause failure occurs when several failures have the same origin. Common cause failures are either common event failures, where the cause is a single external event, or common mode failures, where two systems fail in the same way for the same reason. Common mode failures can occur at different times because of a design defect or a repeated external event. Common event failures reduce the reliability of on-line redundant systems but not of systems using off-line spare parts. Common mode failures reduce the dependability of systems using off-line spare parts and on-line redundancy.

  10. Application of workshop mode for head nurses in nursing management theory study of head nurse training%应用工作坊模式对护士长进行理论培训

    Institute of Scientific and Technical Information of China (English)

    袁湘瑜

    2012-01-01

    目的:探讨工作坊模式对护理管理者培训的效果.方法:根据目前护理管理队伍中对护理管理知识的需求,将一种新的培训方式一工作坊模式应用于临床护士长的培训中.结果:培训前后发放问卷调查显示,受训的护士长认为自己在沟通技巧、时间管理和授权、群体合作、领导才能、对护理人员的支持、激励技巧等方面认为比上课前提升,经统计学处理,有显著性差异(P<0.01).结论:工作坊模式作为一种新的培训模式,提供了一个轻松、有趣的学习互动方式,增强了学习效果,提高了护士长的学习兴趣和综合能力.%Objective :To explore the effect of workshop mode for nursing managers training. Methods: According to the present nursing management team for the knowledge of nursing management needs, will be a new training mode - workshop used in clinical nurse training. Results:Through questionnaire survey before and after training, trainee nurses believe in their own communication skills, time management and authorization, teamwork, leadership, to nursing staff's support, motivation skills than before ascension that, statistically, the result has significant difference ( P < 0.01). Conclusion: Workshop mode as a new mode of training,offered a relaxed and interactive approach to learning,enhanced learning, improved students' learning interest and comprehensive ability.

  11. 远程火箭炮通信控制机故障模式及影响分析%Failure Mode and Effect Analysis of Communication Controller of the Long-range Rocket Launcher System

    Institute of Scientific and Technical Information of China (English)

    靳树昌; 胡俊

    2014-01-01

    A communication controller is the kernel equipment of the communication system in a long-range rocket launcher system.As a kind of electronic communication equipment,its failure mechanism is very complex,this brings about enormous difficulties to the fault diagnosis and maintenance support tasks of the equipment support personnel.The failure mode and the effect of the communication controller were analyzed by means of the hardware failure mode and effect analysis method,with the help of analyzing the structure,function,failure mode,failure effect of the communication controller,the failure mode and the effect analysis report of the communication controller in the long-range rocket launcher system was ac-quired.The report can provide the basis for the fault diagnosis and maintenance support of the long-range rocket launcher system.%某型通信控制机是某型远程火箭炮通信系统的核心设备。作为一种电子通信设备,其故障机理十分复杂,给装备保障人员的故障诊断及维修保障工作带来了巨大的困难。采用硬件故障模式及影响分析法对通信控制机故障模式及影响进行分析,通过通信控制机的结构分析、功能分析、故障模式分析、故障影响分析等,最后得出某型远程火箭炮通信控制机故障模式及影响分析报告。该故障模式及影响分析报告可为某型远程火箭炮通信控制机的故障诊断和维修保障提供依据。

  12. Tape recorder failure investigation

    Science.gov (United States)

    Higgins, M. D.; Loewenthal, S. H.; Carnahan, C. C.; Snyder, G. L.

    1996-01-01

    Two end-item tape recorders lost 4:1 mode data recording mode capability at less than half of their 1 6,000-cycle, 4-year operating life. Subsequent life tests on two spare recorders also experienced 4:1 mode data loss at 8,000 and 11,700 cycles. Tear down inspection after completion of the life tests showed that the tape had worn through the alfesil record and reproduce heads. An investigation was initiated to understand the cause of excessive tape head wear and the reasons why the 4:1 mode data rate, low-speed mode is more damaging than the 1:1 mode data rate, high-speed recording mode. The objective was to establish how operating conditions (tape speed, humidity, temperature, stop/start cycles) affects head life with the goal of extending head life on the remaining in-service tape recorders. Another interest was to explain why an earlier vendor life test showed capability beyond 16,000 cycles.

  13. Influence of hydrides orientation on strain, damage and failure of hydrided zircaloy-4; Influence de l'orientation des hydrures sur les modes de deformation, d'endommagement et de rupture du zircaloy-4 hydrure

    Energy Technology Data Exchange (ETDEWEB)

    Racine, A

    2005-09-15

    In pressurized water reactors of nuclear power plants, fuel pellets are contained in cladding tubes, made of Zirconium alloy, for instance Zircaloy-4. During their life in the primary water of the reactor (155 bars, 300 C), cladding tubes are oxidized and consequently hydrided. A part of the hydrogen given off precipitates as Zirconium hydrides in the bulk material and embrittles the material. This embrittlement depends on many parameters, among which hydrogen content and orientation of hydrides with respect to the applied stress. This investigation is devoted to the influence of the orientation of hydrides with respect to the applied stress on strain, damage and failure mechanisms. Macroscopic and SEM in-situ ring tensile tests are performed on cladding tube material (unirradiated cold worked stress-relieved Zircaloy-4) hydrided with about 200 and 500 wppm hydrogen, and with different main hydrides orientation: either parallel or perpendicular to the circumferential tensile direction. We get the mechanical response of the material as a function of hydride orientation and hydrogen content and we investigate the deformation, damage and failure mechanisms. In both cases, digital image correlation techniques are used to estimate local and global strain distributions. Neither the tensile stress-strain response nor the global and local strain modes are significantly affected by hydrogen content or hydride orientation, but the failure modes are strongly modified. Indeed, only 200 wppm radial hydrides embrittle Zy-4: sample fail in the elastic domain at about 350 MPa before strain bands could develop; whereas in other cases sample reach at least 750 MPa before necking and final failure, in ductile or brittle mode. To model this particular heterogeneous material behavior, a non-coupled damage approach which takes into account the anisotropic distribution of the hydrides is proposed. Its parameters are identified from the macroscopic strain field measurements and a

  14. 温压弹爆炸冲击波作用下防护门破坏模式研究%Failure mode of a blast door subjected to the explosion wave of a thermobaric bomb

    Institute of Scientific and Technical Information of China (English)

    李秀地; 耿振刚; 苗朝阳; 杨森

    2016-01-01

    为研究温压弹爆炸冲击波作用下防护门的破坏模式,利用 ANSYS /LS-DYNA 软件建立了考虑材料应变率效应的分离式钢筋混凝土防护门数值计算模型。对防护门加载温压弹爆炸冲击波波形,分析了防护门的挠度、转角和剪应力,并与 TNT 的作用结果进行了对比。结果表明:温压弹爆炸冲击波作用下,随着距爆炸源距离的增加,防护门的破坏模式由直剪破坏、弯剪耦合破坏逐渐变为弯曲破坏;防护门的响应与温压弹爆炸冲击波的高冲量有关,温压弹爆炸冲击波作用下防护门的破坏程度大于 TNT 的作用结果;防护门跨中速度值可以用来快速评估防护门的破坏模式。%To reveal the failure mode of a blast door subjected to the explosion wave of a thermobaric bomb,a separate reinforced concrete numerical model considering strain rate effects of a blast door was established with the dynamic finite element software ANSYS /LS-DYNA.The explosion wave of a thermobaric bomb was loaded on the blast door and the deflection and shear stress of the blast door were analyzed and compared with the shock wave of TNT.The results show that with the distance from explosion increasing,the failure mode of blast door under the thermobaric bomb gradually changes from punching shear failure and mixed flexural-shear failure to flexural failure.The dynamic response of the blast door is related to the high impulse of the thermobaric bomb,and the damage of the blast door under the thermobaric bomb is more serious than that under TNT.The velocity of the mid span can be used to estimate the failure mode of the blast door.

  15. Software Failure Modes and Effect Analysis Method C ombined with Ontology and Rule Reasoning%结合本体和规则推理的 SFMEA 方法研究

    Institute of Scientific and Technical Information of China (English)

    朱羿全; 沈国华; 康达周; 廖莉莉

    2015-01-01

    安全关键软件一旦失效将造成严重后果。软件失效模式和影响分析( Software Failure Modes and Effect Analysis , SFMEA)是一种工业界常用的软件安全性分析方法。由于SFMEA依赖人工分析,存在信息共享性差、分析准确性低等问题。针对上述问题,提出一种结合本体和规则推理的SFMEA方法。首先,构建了支持失效知识表示的SFMEA本体,实现软件失效知识的精确语义描述。在此基础上,以规则描述语言SWRL来定义失效规则,通过分析失效原因,实现对失效造成影响的自动化推理。最后,结合一个发动机熄火判断模块的案例分析,说明该方法的可行性和实用性。%Failures in safety-critical software will lead to catastrophic consequences .Software failure modes and effect analysis (SFMEA) is a safety analysis method which is commonly used in industry .However, the SFMEA method relies on manual analy-sis, thus it has poor reusability and low accuracy .To solve these problems ,this paper proposes a creative SFMEA method com -bined with ontology and rule reasoning.Firstly, the SFMEA ontology is developed to accurately describe the software failure knowledge.Secondly, rules are built to describe the failure analysis processes using semantic web rule language (SWRL).Ac-cording to the failure causes , the reasoning engine can analyze the failure effects automatically .At last, a case study of engine flameout-state module analysis confirms the feasibility and practicality of the research .

  16. The Analysis of the Cutting Tool Failure Mode in the Modern Mechanical Manufacturing Industry%现代机械制造业中的刀具失效形式分析

    Institute of Scientific and Technical Information of China (English)

    田育

    2011-01-01

    The condition of cutting tool materials is pointed out, the main failure mode of cutting tools which are made with different materials is summed up. The thorough investigation is made on the cutting tool wear part and wear mechanism. It is very beneficial for putting forward measures to reduce cutting tool failure.%本文分析了机械加工中刀具材料满足的基本条件,通过调查分析总结了不同材料刀具的主要失效形式,最后对刀具磨损的部位和刀具磨损的原因进行了深入的研究,为生产上提出减少刀具失效的措施提供了有利条件.

  17. The Application of Failure Modes in PDA Mobile Nursing System Construction%失效模式在PDA移动护理系统建设中的应用

    Institute of Scientific and Technical Information of China (English)

    胡外光; 陈敏莲; 凌科峰; 胡珊珊

    2014-01-01

    运用失效模型和效果分析(Failure Modes and Effects Analysis,FMEA)作为移动护理系统质量改进的工具,介绍具体操作方法并提出改进措施,减少移动护理系统故障和错误发生率,保证系统日常使用处于良性状态,促进护理质量和护理信息化水平的提高.

  18. Failure Modes, Effects and Criticality Analysis of Machining Center%加工中心的故障模式、影响及其危害性分析

    Institute of Scientific and Technical Information of China (English)

    张航军; 戴怡

    2007-01-01

    以某型号加工中心一年内的故障数据为依据,对其进行了故障模式、影响及其危害性分析(Failure Mode,Effects and Criticality Analysis),这样不仅在一定程度上评价了该型号加工中心的可靠性水平,而且识别出了其薄弱环节和关键项目,进而为设计、制造和使用提出改进措施和建议.

  19. Comparison of image quality between axial and spiral scan mode in routine head CT%常规头部CT螺旋扫描与轴扫描模式的影像质量对照

    Institute of Scientific and Technical Information of China (English)

    傅强; 刘晓菲; 于虹; 徐克

    2012-01-01

    目的 通过头部CT螺旋扫描和轴扫描两种不同扫描模式的影像质量对照,探讨常规头部CT采用螺旋扫描模式取代轴扫描模式的可行性.方法 40例患者,其中男性24例,女性16例;年龄18 ~ 74岁,平均年龄46岁.分别接受头部CT螺旋扫描和轴扫描两种不同模式扫描,轴扫描参数:140 kV、170 mA用于颅底部;120 kV、150 mA用于颅脑部,每周2s.螺旋扫描参数:120 kV,150 mA,每周0.6 s.扫描剂量直接取自设备剂量指示值(CTDI和DLP).影像质量分别由2位专家采用双盲法,对头部CT的颅底、脑灰-白质层面及全部影像逐层进行CT值测量评估.结果 常规头部CT螺旋扫描模式较轴扫描模式可有效去除颅底部伪影,并能减少扫描时间和扫描剂量(轴扫描模式与螺旋扫描模式对比,CTDI 55.43 mGy/37.80 mGy;DLP 662.10 mGy· cm/498.28 mGy· cm;扫描时间12.0 s/7.2 s)(P< 0.001).结论 常规头部CT螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,并可取代轴扫描模式.同时常规头部CT螺旋扫描模式还具有可减少扫描时间和辐射剂量,并可进行影像的二维和三维后处理,有利于提高微小病灶正确诊断率的优越性.%Objective To assess the feasibility of replacing axial CT scan mode with spiral CT scan mode in routine head CT through comparing the image quality between spiral and routine axial (sequential) acquired head CT. Methods A total of 40 cases were enrolled, male 24, female 16; aged 18 - 74 years old, mean age 46 years old. They were performed spiral scan and axial scan, respectively. Scan parameter axial mode were 140 kV, 170 mA for petrou bone, and 120 kV, 150 mA for brain, scan time 2.0 s/rol; and spiral mode were 120 kV, 150 mA, scan time 0.6 s/rol. Radiation dose were measured directly from the CT scan indicated computed tomography dose index (CTDI) and dose-length product (DLP). The image quality at the level of the posterior fossa and grey -white matter

  20. Application of Failure Mode and Effects Analysis in Motor Protection Circuit Breaker Design%失效模式与后果分析在电动机保护断路器设计中的应用

    Institute of Scientific and Technical Information of China (English)

    蒋晓锋

    2015-01-01

    针对传统失效模式与后果分析(FMEA)在面对复杂系统时存在的系统描述不清的问题,提出自上而下的功能建模方法。以电动机保护用断路器为例,利用DFMEA 自上而下分析了产品各级系统之间的影响后果、失效模式、起因,并采取针对性的纠正措施以及实施后的效果验证。结果验证能有效控制设计风险。%The traditional Failure Mode and Effects Analysis(FMEA)method can not describe the complex system clearly.Aiming at the problem,the functional modeling method of top-down was put forward.Taking a motor protection circuit breaker for example,the relations of failure modes,effects and causes of various levels were analyzed based on DFMEA top-down method,and the pertinent corrective actions were applied and the action results were verified.

  1. 失效模式与效应分析在预防胃管意外滑脱中的应用%Application of Failure Mode and Effect Analysis in Prevention of Slippage of Gastric Catheter

    Institute of Scientific and Technical Information of China (English)

    洪利芬; 何冬伟; 李晨玲; 李芳芹

    2012-01-01

      Objective To discuss the effect of failure mode and effect analysis (FMEA) in prevention of gastric catheter slippage. Methods Potential causes to catheter slippage were analyzed with FMEA and the factors were calculated,in order to deal wtih and reduce the catheter slippage. Results The RPN has descended from 1656 to 373, and the rate of danger is 77.5%. Conclusion Application of FMEA in prevention of accidental removal (pulling) out of gastric catheter can effectively reduce the rate of catheter slippage.%  目的探讨失效模式与效应分析(failure mode and effect analysis,FMEA)在预防胃管意外滑脱中的应用效果.方法在胃管留置过程中,应用FMEA对胃管留置过程中可能出现脱管的原因进行分析,计算危机值找出优先需要干预的因素,采取应对措施,从环节上寻找原因杜绝其脱管.结果危机值由FMEA实施前的1656分降至373分,危机值下降率为77.5%.结论 FMEA应用于预防胃管意外脱(拔)管中,能有效地降低脱管率.

  2. 失效模式和效应分析在降低医院医疗差错中的应用%Application of failure mode and effect analysis in reducing hospital medical errors

    Institute of Scientific and Technical Information of China (English)

    毕玉田; 唐静; 文爱清; 王毅; 程晓斌; 周林

    2011-01-01

    随着临床风险管理成为医院管理的一个重要组成部分,降低医疗差错、确保患者安全已成为质量管理的一个重要过程.失效模式和效应分析(failure mode and effect analysis,FMEA)是发现并减少医疗差错的一个重要的前瞻性方法.在简要回顾FMEA发展历史的基础上,详细描述FMEA的实施方法和步骤,重点介绍FMEA应用于降低医院医疗差错的研究进展.%As the importance of clinical risks management grows hospital management,reducing hospital medical errors for patients safety has become a key quality management process.Failure Mode and effect analysis( FMEA) is a proactive technique for error detection and reduction.In this paper,based on a brief review of it's history of development,described in detail the implementation method and steps of FMEA,mainly introducing the research progress for using FMEA in reducing hospital medical errors.

  3. FINITE ELEMENT ANALYSIS OF FAILURE MODES OF BLAST-LOADED R/C BEAMS%爆炸荷载作用下钢筋混凝土梁破坏形态有限元分析

    Institute of Scientific and Technical Information of China (English)

    方秦; 柳锦春; 张亚栋; 钱七虎

    2001-01-01

    The flexural failure mode of R/C frames or beams is usually observed in case of blast loads with long duration. However, shear failure mode may occur before the flexural failure takes place in case of blast loads with short duration such as impulsive loadings induced by chemical explosion. This phenomenon is observed in both laboratory and in-situ tests. The reason is that the impulsive loading excites the shear force in the component of the structures and causes the structures fail in the manner of shear failure. Based on Timoshenko beam theory, a non-linear layered beam element is proposed in this paper to investigate the response and failure modes of blast-loaded R/C beams. Non-linear material properties, strain-rate effects of concrete and steel are taken into account in the material models. The dynamic responses and various failure modes, including flexure, flexure-shear and shear of the blast-loaded R/C beams are predicted. A good agreement between the numerical results and experimental results is reached.%在持续时间较长的爆炸荷载作用下,钢筋混凝土框架或梁通常会发生常见的弯曲破坏形态,但是在持续时间较短的爆炸荷载,如化学爆炸产生的脉冲荷载作用下,钢筋混凝土结构有可能在弯曲破坏发生之前产生剪切破坏。这种现象已被室内外试验所证实,其原因是脉冲荷载激发了结构中的剪力,从而使结构产生剪切破坏。为了预报钢筋混凝土梁在爆炸荷载下的响应和破坏形态,本文提出了一种基于Timoshenko梁理论的非线性分层梁有限元法。在材料模型中考虑了混凝土和钢筋的非线性和应变速率效应等因素。应用这方法,本文计算分析了爆炸荷载作用下钢筋混凝土梁的动态响应以及弯曲、弯剪和剪切等不同的破坏形态,计算预报的结构动态响应和破坏形态与现场试验结果有较好的一致性。

  4. Seismic potential failure mode analysis of concrete gravity dam based on extended finite element method%基于扩展有限元法的重力坝强震潜在失效模式分析

    Institute of Scientific and Technical Information of China (English)

    张社荣; 王高辉; 孙博; 王超

    2012-01-01

    The extended finite element method (XFEM) can make the characterization of discontinuous displacement field independent of cell boundaries by enriching discontinuous displacement mode on the influence domain of related nodes. Therefore XFEM possesses the capacity of effective describing the crack propagation in concrete. The damaged process and failure mode of Koyna gravity dam subjected to earthquake was analyzed using XFEM. The computed distribution of cracking damage is consistent with the actual condition and the model test results in literature, which verifies the validity of the calculation model. Considering the spectral characteristics of ground motion, we conducted numerical simulation of the dynamic damaged process of a concrete gravity dam based on a reasonable seismic wave. The potential failure mode of the dam under strong earthquake ground motion was generalized from the simulation results. Our work can provides the basis for the seismic design, construction safety hazard rate analysis under particular failure mode and flood routing.%扩展有限元法(XFEM)通过在相关节点的影响域上富集非连续位移模式,使得对非连续位移场的表征独立于单元边界,可以有效描述混凝土中的裂纹扩展。以Koyna重力坝为例,采用XFEM分析了大坝地震渐进破坏过程和失效模式,数值模拟结果与文献中的模型试验结果基本一致,验证了计算模型的有效性。考虑地震动频谱特性的影响,采用合理的地震波对国内某混凝土重力坝强震下的动力破坏过程进行了数值仿真分析,得到了不同水平地震作用下的大坝破坏形态,并概化出强震作用下混凝土重力坝的潜在失效模式,为大坝抗震设计、特定失事模式下的工程安全风险率分析及洪水演进提供计算基础。

  5. Step-path failure mode and stability calculation of jointed rock slopes%岩质边坡断续裂隙阶梯状滑移模式及稳定性计算

    Institute of Scientific and Technical Information of China (English)

    岑夺丰; 黄达; 黄润秋

    2014-01-01

    Step-path failure is a kind of typical instability mode in rock slopes. Based on the summary of geological structural features of jointed rock slopes, the step-path failure mode and evolution process are studied by using the discrete element method, particle flow code in two dimensions (PFC2D). Three rock bridge failure modes in slopes can be summarized:tensile coalescence, shear coalescence and mixed tensile-shear coalescence. Through the evolution analysis of the rock mesoscopic particle bond force vector field, stress state of rock bridges and rock bridge failure, the progressive step-path failure process that rock bridge fractures one by one from the bottom up under the action of gravity is revealed, and the tensile crack development in the trailing edge of slope is due to the traction of lower part of slope. Take the slope with shallow dipping step-path parallel fissures for example (dip angle of rock bridge is 90°, and that of fissure is 30°), the step-path failure process can be distributed into four stages: elastic steady deformation of slope, failure of the lower rock bridges, failure of the upper rock bridges and development of tensile crack in the trailing edge of the slope, and the overall slipping of the slope along the failure surface. It is the critical state of instability at stage No. three that slip band sufficiently extends with micro-cracks expanding dramatically. Based on the understanding of failure modes and evolution process, three slope stability models for the step-path failure by shear coalescence, tensile coalescence and mixed tensile-shear coalescence of rock bridges are established, and the limit equilibrium formulae for the safety factor of slopes considering strength and coalescence coefficient of rock bridges are deduced.%阶梯状滑移破坏是一类典型岩质边坡破坏失稳模式。在总结断续裂隙阶梯状滑移的岩质边坡地质结构特征的基础上,利用离散元二维颗粒流程序(PFC2D)模拟研

  6. Buckling failures in insect exoskeletons.

    Science.gov (United States)

    Parle, Eoin; Herbaj, Simona; Sheils, Fiona; Larmon, Hannah; Taylor, David

    2016-02-01

    Thin walled tubes are often used for load-bearing structures, in nature and in engineering, because they offer good resistance to bending and torsion at relatively low weight. However, when loaded in bending they are prone to failure by buckling. It is difficult to predict the loading conditions which cause buckling, especially for tubes whose cross sections are not simple shapes. Insights into buckling prevention might be gained by studying this phenomenon in the exoskeletons of insects and other arthropods. We investigated the leg segments (tibiae) of five different insects: the locust (Schistocerca gergaria), American cockroach (Periplaneta americana), death's head cockroach (Blaberus discoidalis), stick insect (Parapachymorpha zomproi) and bumblebee (Bombus terrestris audax). These were tested to failure in cantilever bending and modelled using finite element analysis (FEA). The tibiae of the locust and the cockroaches were found to be approximately circular in shape. Their buckling loads were well predicted by linear elastic FEA, and also by one of the analytical solutions available in the literature for elastic buckling. The legs of the stick insect are also circular in cross section but have several prominent longitudinal ridges. We hypothesised that these ridges might protect the legs against buckling but we found that this was not the case: the loads necessary for elastic buckling were not reached in practice because yield occurred in the material, causing plastic buckling. The legs of bees have a non-circular cross section due to a pollen-carrying feature (the corbicula). We found that this did not significantly affect their resistance to buckling. Our results imply that buckling is the dominant failure mode in the tibia of insects; it likely to be a significant consideration for other arthropods and any organisms with stiff exoskeletons. The interactions displayed here between material properties and cross sectional geometry may provide insights for the

  7. 饱水裂隙破坏模式及影响因素理论分析%Theoretical Analysis of Failure Mode of Water-saturated Fissure and Its Influencing Factors

    Institute of Scientific and Technical Information of China (English)

    廖斌; 黄厚旭; 戎晓力; 张志成

    2016-01-01

    A large amount of fissures would occur on tunnel face and tunnel sidewalls during deep long karst tunnel excavation.Due to the interaction of far-field stress and water pressure,the fissures would be expanded and the water flow rate will be increased.As a result,large-scale water and mud gushing would occur.The mechanism of internal water effect of fissures is considered to be hydraulic fracture effect and hydrostatic expansion effect popularly.The critical water pressure stresses of tenso-shear failure and compression-shear failure in conditions of plane strain are calculated based on fracture mechanics and fluid mechanics.The calculated results show that the critical water pressure stress of tenso-shear failure is larger than that of compression-shear failure.The compression-shear failure is the main failure mode of water-saturated fissure.%深长岩溶隧道掘进过程中掌子面和隧道两侧壁将出现大量裂隙,裂隙在远场应力与水压力的共同作用下将发生扩张膨胀,使得通过裂隙的水流量增大并最终导致隧道发生大范围的突水突泥事件。受水压致裂技术的影响,一般认为裂隙内部水流作用的机制是由水力劈裂和水压扩径造成的。基于断裂力学和流体力学,在平面受力情况下求解含水裂隙发生劈裂破坏和压剪破坏所需的临界水压值,并将两者进行比较后发现,同一裂隙发生水力劈裂破坏所需的临界水压大于其发生压剪破坏所需的临界水压,得出压剪破坏是含水裂隙破坏的主要形式。

  8. Head Injuries

    Science.gov (United States)

    ... object that's stuck in the wound. previous continue Concussions Concussions — the temporary loss of normal brain function due ... also a type of internal head injury. Repeated concussions can permanently damage the brain. In many cases, ...

  9. Head Tilt

    Science.gov (United States)

    ... Healthy Living Healthy Living Healthy Living Nutrition Fitness Sports Oral Health Emotional Wellness Growing Healthy Sleep Safety & ... When this happens, the neck muscles go into spasm, causing the head to tilt to one side. ...

  10. Head Injuries

    Science.gov (United States)

    ... ATV) Safety Balance Disorders Knowing Your Child's Medical History First Aid: Falls First Aid: Head Injuries Preventing Children's Sports Injuries Getting Help: Know the Numbers Concussions Stay Safe: Baseball Concussions Concussions: Getting Better Sports and Concussions Dealing ...

  11. Head MRI

    Science.gov (United States)

    ... heart valves Heart defibrillator or pacemaker Inner ear (cochlear) implants Kidney disease or dialysis (you may not ... to: Abnormal blood vessels in the brain ( arteriovenous malformations of the head ) Tumor of the nerve that ...

  12. Component-based failure mode and effect analysis for flight control systems%飞行控制系统组件化故障模式与影响分析方法

    Institute of Scientific and Technical Information of China (English)

    马勇; 马建峰; 孙聪; 张双; 崔西宁; 李亚晖

    2016-01-01

    The conventional approaches of failure mode and effect analysis (FMEA) have not considered the mutual-influence between failure modes as well as the component-based design of systems. In this paper, we propose a new compositional approach of FMEA. We use fuzzy numbers instead of accurate numbers to describe the risk factors such as occurrence, severity, and detection in FMEA. To improve the accuracy of conventional FMEA, we construct the hierarchical FMEA graph and the respective influence matrix for each component. Then we derive the influence vector for the failure modes and leverage this vector to amend the risk priority numbers of conventional FMEA. The analysis of a practical flight control system shows the usability of our approach. Simulation results show that our compositional approach is more efficient than the non-compositional approach.%针对传统故障模式与影响分析方法未考虑组件化设计和故障模式间相互影响的问题,提出一种组件化故障模式与影响分析方法.使用模糊数代替精确数值以描述风险因子,通过构造分层故障模式与影响分析图和影响矩阵,计算出故障模式集合上的影响向量,并以此修正传统故障模式与影响分析的风险优先数.通过对实际飞行控制系统设计的组件化故障模式与影响分析,说明这种方法的实用性,并通过与非组件化方法的仿真实验比较,说明组件化方法的分析效率优势.

  13. The Self-healing Mode of Rapid Restoration Urban Power Network Failure Research%城市电网故障快速复电的自愈模式

    Institute of Scientific and Technical Information of China (English)

    郭上华

    2011-01-01

    The technology of Rapid restoration Urban Power Network failure is an effective method to improve the security and stability of urban power network and enhance the service level, which will be important applications of the intelligent power grid. This paper analyzes the status of 10kV distribution network failure first and then proposes self-healing mode construction ideas of knowing-power outage, decreasing-power outage and avoiding-power outage according to how to deal with higher frequency of failure for the overhead lines and overhead cables mixed lines. It puts forward the failure local processing of the main lines, branch lines and user lines, model and layout of Feeder automation intelligent equipment. At last, It is demonstrated that the self-healing mode is feasible through projects.%故障快速复电是提高城市电网安全稳定运行和优质服务水平的有效手段,是智能配电网建设的重要应用。文中分析了lOkV配电线路故障现状,针对故障频次较高的架空线路和架空电缆混合线路如何实现快速复电,阐述了知停电、少停电和防停电的线路自愈模式建设思路,围绕主干线、分支线和用户线故障就地智能处理,对馈线自动化智能设备的选型、布点进行了总结与思考。最后通过工程实践验证了就地智能自愈模式在城市电网故障快速复电建设中的可行性。

  14. Structural and failure mechanics of sandwich composites

    CERN Document Server

    Carlsson, LA; Carlsson, Leif A

    2011-01-01

    Focusing on important deformation and failure modes of sandwich structures, this volume describes the mechanics behind fracture processes. The text also reviews test methods developed for the cr, structural integrity, and failure mechanisms of sandwich structures.

  15. 动力定位系统故障模式与后果分析中的关键点%Key Elements of Failure Mode and Effect Analysis for Dynamic Positioning System

    Institute of Scientific and Technical Information of China (English)

    刘潇; 冯舒

    2012-01-01

    Position loss is the main risk of the application of Dynamic Positioning (DP) system in offshore industry. To avoid position loss accident, DP reliability is achieved through the redundancy design of the system. Major classification societies require a Failure Mode and Effect Analysis (FMEA) to be performed to verify the redundancy of the DP system. Level of details and quality of the FMEA work directly affects the reliability design of the system. This paper introduces the DP FMEA methodology and discusses the key elements of DP FMEA with examples. Recommendations are also proposed accordingly to include industry best practice in the future DP FMEA work.%移位风险是动力定位(Dynamic Positioning,简称DP)系统在海洋工程领域应用过程中的最主要风险,设计中通过采用较高级别的冗余度提高系统的可靠性,避免移位事故的发生.各大船级社都要求通过故障模式与后果分析(Failure Mode and Effect Analysis,简称FMEA)的方式对动力定位系统的冗余度进行验证,分析的深度和质量直接关系到动力定位系统的可靠性设计.本文介绍了DP FMEA分析方法,并通过实例讨论了成功开展DP FMEA分析的几个关键点,为未来开展类似的工作提出相关建议.

  16. 医疗失效模式与效应分析在降低胃管滑脱率中的应用%Application of Healthcare Failure Mode and Effect Analysis in decreasing the incidence of gastric tube slippage

    Institute of Scientific and Technical Information of China (English)

    朱珍; 徐波; 于媛

    2013-01-01

    Objective To explore the effects of healthcare failure mode and effect analysis ( HFMEA) in decreasing the incidence of gastric tube slippage. Methods According to the process of HFMEA, the methods included determining the subject, establishing team, formulating the flow chart, analyzing the possible mode,reasons and results of failure and severity, possibility and crisis value,formulating and implementing the improvement measures. Result The incidence of gastric tube slippage decreased from 3. 52% to 0.45% (P <0.05). Conclusion Utilization of HFMEA is effective on refining gastric tube nursing process, thus to decrease the rate of gastric tube slippage.%目的 探讨医疗失效模式与效应分析在降低胃管滑脱率中的应用效果.方法 根据医疗失效模式与效应分析工作流程,确定主题,组建团队,制订流程图,分析各流程步骤中的潜在失效模式、失效原因及失效结果,进行严重度、可能性、危机值分析,根据分析结果制订相应改进措施并落实.结果 胃管脱出率由3.52%下降至0.45% (P <0.05).结论 应用医疗失效模式与效应分析有助于细化胃管护理流程,降低胃管脱出率.

  17. Analysis on the Failure Mode of Power - operated High - speed Precision Chuck%高速精密动力卡盘的失效形式分析研究

    Institute of Scientific and Technical Information of China (English)

    龚俊; 汤文成; 韦鸣; 张震宇

    2012-01-01

    对高速精密动力卡盘的失效形式进行了分析研究,提出了避免在预定寿命期内失效的要求,建立了失效鱼骨图.分析动力卡盘的材料选择和热处理技术、摩擦磨损和精度对动力卡盘失效的影响,对卡盘的优化设计和应用以及夹紧力计算具有指导意义.%It analyzes the failure mode of power - operated high speed precision chuck, proposes the requirements of failure in the lifespan, builds the fishbone diagram. It gives the detail about the impact of the material selection of chuck and heat treatment technology, the precision impact analysis on wear and tear. The results provide reliable technical supports for the optimization of the design and application of power - operated high speed precision chuck.

  18. Failure Mode and Operation Strategy of Thermal Resistance Temperature Measurement System%热电阻测温系统的故障模式及运行对策

    Institute of Scientific and Technical Information of China (English)

    秦华蔚; 杨斌; 高天云

    2012-01-01

    通过介绍热电阻(RTD)测温系统的特点和三线制接线方式,总结了近年来华东电网几个抽水蓄能电站RTD测温系统发生的故障,经过对五类样品典型RTD故障模式的剖析以及失效机理的分析,提出了完善和提高抽水蓄能电站RTD测温系统可靠运行的措施与建议。%Through introduction of the characteristics of resistance temperature measurement system ( RTD ) and three wire connection mode of East China Power Grid in recent years, summarizes several pumped storage power station RTD thermometry system failures. Through mechanism analysis of five samples of typical RTD failure, the measures and the suggestions to perfect and improve reliable operation of the pumped storage power station RTD thermometry system have been established.

  19. European Extremely Large Telescope (E-ELT) availability stochastic model: integrating failure mode and effect analysis (FMEA), influence diagram, and Bayesian network together

    Science.gov (United States)

    Verzichelli, Gianluca

    2016-08-01

    An Availability Stochastic Model for the E-ELT has been developed in GeNIE. The latter is a Graphical User Interface (GUI) for the Structural Modeling, Inference, and Learning Engine (SMILE), originally distributed by the Decision Systems Laboratory from the University of Pittsburgh, and now being a product of Bayes Fusion, LLC. The E-ELT will be the largest optical/near-infrared telescope in the world. Its design comprises an Alt-Azimuth mount reflecting telescope with a 39-metre-diameter segmented primary mirror, a 4-metre-diameter secondary mirror, a 3.75-metre-diameter tertiary mirror, adaptive optics and multiple instruments. This paper highlights how a Model has been developed for an earlier on assessment of the Telescope Avail- ability. It also describes the modular structure and the underlying assumptions that have been adopted for developing the model and demonstrates the integration of FMEA, Influence Diagram and Bayesian Network elements. These have been considered for a better characterization of the Model inputs and outputs and for taking into account Degraded-based Reliability (DBR). Lastly, it provides an overview of how the information and knowledge captured in the model may be used for an earlier on definition of the Failure, Detection, Isolation and Recovery (FDIR) Control Strategy and the Telescope Minimum Master Equipment List (T-MMEL).

  20. 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.

  1. 某型载货汽车前桥横拉杆断裂失效模式分析%A type of truck front axle tie rod fracture failure mode analysis

    Institute of Scientific and Technical Information of China (English)

    张传业

    2012-01-01

    因某型轻型载货汽车前桥转向横拉杆连续出现断裂现象,需要分析其断裂模式和原因,提出改进措施和方法。通过建立零件三维模型,导入ansys中进行仿真,并与计算结果进行比较。结果计算与仿真结果与文中假设的失效模式一致。最终得出应力集中是导致该故障发生的主要原因,根据文中的提出的改进方法进行实施后,问题得到解决。%for a certain type of light truck front axle steering tie rod continuous cracking, needs the analysis of its fracture mode and reason, put forward the improvement measures and methods. Through the establishment of three-dimensional part model, through ANSYS simulation, and the results were compared with. The results of calculation and simulation results and the failure mode consistent hypothesis. Finally obtains the stress concentration is the main cause of the fault, according to the proposed method implemented, problems to be resolved.

  2. 现浇楼板对RC框架结构破坏模式影响的有限元分析%Finite Element Simulation for the Effect of Casting Slabs on The Failure Mode of Reinforced Concrete Frame Structures

    Institute of Scientific and Technical Information of China (English)

    杨迎春; 杨智良; 邱磊

    2012-01-01

    运用通用有限元程序ANSYS的参数化设计语言功能分别对带楼板的钢筋混凝土框架结构和不带楼板的纯框架结构进行了地震作用下的时程分析,得到了在地震作用的各个阶段,框架结构的裂缝发生和发展情况.通过将两种模型的模拟结果进行对比分析,证明楼板对钢筋混凝土框架的破坏模式会产生影响,带楼板的框架结构更难实现“强柱弱梁”.%Finite element models with floors and without floors are established by general structure analysis software ANSYS. According to the nonlinear time-history response, the vibration modes of the RC frame structure were calculated, the development process of frame crack under different acceleration peak was obtained. Two models by a comparative analysis of the simulation results show that slab of reinforced concrete frame will affect the failure mode, frame structure with a floor more difficult to achieve "strong-column weak-beam. "

  3. Head Start.

    Science.gov (United States)

    Greenman, Geri

    2000-01-01

    Discusses an art project in which students created drawings of mop heads. Explains that the approach of drawing was more important than the subject. States that the students used the chiaroscuro technique, used by Rembrandt and Caravaggio, in which light appears out of the darkness. (CMK)

  4. Implementation of a computational system at the Center for Nuclear Technology Development, for systematization the application of the FMEA - Failure Mode and Effects Analysis, for identification of dangerous and developed risks evaluation; Implementacao de um sistema computacional no Centro de Desenvolvimento da Tecnologia Nuclear para sistemarizar a aplicacao da tecnica FMEA - Failure Mode and Effects Analysis - na identificacao de perigos e avaliacao de riscos desenvolvida

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Danyel Pontelo; Vasconcelos, Vanderley de, E-mail: dpc@cdtn.b, E-mail: vasconv@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

    2009-07-01

    The regulatory bodies request risks evaluations for nuclear and radioactive licensing purposes. In Brazil those evaluations are contained by the safety analysis reports requested by the Brazilian Nuclear Energy Commission (CNEN), and risk analysis studies requested by the environment organisms. A risk evaluation includes the identification of the risks and the accident sequence which can occur, and the estimation of the frequency and his undesirable effects on the industrial installations, the public, and the environment. The identification and the risk analysis are particularly important for the implementation of a health, environment and safety integrated management according to the regulation instruments ISO 14001, BS 8800 and OHSAS 18001. The utilization of the risk identification techniques and the risk analysis is performed at the non nuclear industry, in a non standard form by the various sectors of an enterprise, diminishing the effectiveness of the recommended actions based on risk indexes. However, for the nuclear licensing, the CNEN request through their regulatory instruments and standard formats, that the risks, the failure mechanisms and detection be identified, which can allow the preventive and mitigate actions. This paper proposes the utilization of the FMEA (Failure Mode and Effects Analysis) technique in the licensing process. It was implemented a software through the Excel program, using the Visual Basic for Applications program which allows the automation and the standardization of FMEA studies as well

  5. Using Different Approaches to Study the Failure Mode and Stability of the Gravity Dam on Complex Foundation%复杂地基上重力坝的破坏过程及稳定安全度研究

    Institute of Scientific and Technical Information of China (English)

    李征; 张林; 陈媛; 黄刚海

    2016-01-01

    The overall stability of the gravity dam on complicated foundation has always been a great concern .In order to analyze the global stability and failure mode of the gravity dam on complicated foundation ,this paper applies the method of three-dimensional geomechanical model test to the typical dam section of a certain water hinge which has complicated geological conditions and the prob‐lem of anti-sliding stability .And overloading method failure test is used for the scheme of natural foundation .By picturing the dam‐age process of dam foundation ,the distribution characteristics of deformation and failure form ,obtain the overloading coefficient is 3 .0 .Then considering the finite element ,recalculate by the Synthetical Measure ,obtain the synthetical coefficient is 2 .5 .The meth‐ods of model test and calculating lead to the similar dam failure instability process ,as a solid proof of the accuracy and reliability of the engineering stability analysis results .The research methods and results can provide references for similar problems where the Synthetical Measure is applied .%复杂地基上重力坝的整体稳定一直备受关注。为了对复杂地基上重力坝整体稳定及破坏过程进行研究,对某水电枢纽典型坝段进行三维地质力学模型试验,采用超载法对该水电枢纽天然地基方案的典型坝段进行破坏试验。得到坝基的破坏过程及变形变位特点,并得出超载安全系数 Kp =3.0。再结合有限元,采用综合法进行计算,所得综合安全系数 Kc=2.5。模型试验和计算所得大坝破坏失稳过程相似,两者进行对照,相互验证确保工程稳定分析成果的准确性与可靠性,且研究成果可为类似问题中综合法的使用提供借鉴和参考。

  6. Heart Failure

    Science.gov (United States)

    ... heart failure due to systolic dysfunction. http://www.uptodate.com/home. Accessed Sept. 26, 2014. Colucci WS. ... patient with heart failure or cardiomyopathy. http://www.uptodate.com/home. Accessed Sept. 26, 2014. Colucci WS. ...

  7. Air modes of the Bacon internal resonator banjo

    CERN Document Server

    Politzer, David

    2016-01-01

    Sound measurements on a sequence of related, similar constructions with slightly different dimensions confirm a simple picture of the air modes of the internal resonator banjo's body. For the purpose of this study, the air modes are decoupled from the soundboard (i.e., [drum] head) modes by replacing the head with 3/4" plywood. The resulting characteristic features survive the strong coupling of the air modes to the head and are in accord with the qualitative distinctions recognized by banjo players.

  8. 复合材料夹芯梁屈曲破坏模式及极限承载%Buckling failure mode and ultimate load of composite sandwich beam

    Institute of Scientific and Technical Information of China (English)

    陈悦; 朱锡; 李华东; 朱子旭

    2016-01-01

    In order to investigate the buckling,postbuckling characteristics and load capacity of composite sand-wich beam under the effect of axial compression,test investigation and finite element simulation were carried out. Firstly,a series of buckling characteristic tests of composite sandwich beams were conducted.The effects of ply ra-tio angle,length of beam,face layer thickness and core layer thickness on buckling,postbuckling failure modes and ultimate load were discussed.Then,based on the nonlinear buckling theory,3D cohesive interface elements were used to simulate the debond between skin and core,and initial predeformation as well as material damage criteria were also introduced to simulate and investigate the buckling characteristics and ultimate load of composite sandwich beam under axial compression.The results show that interface debond is the important mode of buckling failure. Comparing the ultimate load calculated by simulation with the test results,the errors are controlled within 10%. The conclusions obtained prove that the method can predict the postbuckling path,failure mode and ultimate load ac-curately.%为研究复合材料夹芯梁在轴压作用下的屈曲、后屈曲特性及承载能力,进行了试验研究与有限元仿真。首先,开展了系列复合材料夹芯梁屈曲特性试验,研究了铺层比例、梁长度、表层厚度及芯层厚度等因素对其屈曲、后屈曲破坏模式及极限承载的影响;然后,基于非线性屈曲理论,采用三维内聚力界面单元模拟面芯脱粘,并引入初始预变形及材料损伤准则对复合材料夹芯梁在轴压下的屈曲特性及极限承载进行仿真研究。结果显示:界面脱粘是屈曲破坏的重要模式;仿真计算的极限承载与试验结果相比,误差控制在10%以内。所得结论表明该方法可有效预报复合材料夹芯梁的后屈曲路径、破坏模式及极限承载。

  9. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... Professions Site Index A-Z Computed Tomography (CT) - Head Computed tomography (CT) of the head uses special ... the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a CT ...

  10. Calculation of the Actual Failure Rate of a DSP Board Using the FMEDA

    Energy Technology Data Exchange (ETDEWEB)

    Keum, Jong Yong; Suh, Yong Suk; Jang, Gwi Sook; Park, Je Yun [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2008-10-15

    Most components have multiple failure modes and these failure modes are more or less important depending on how they are used within a particular design. Though a component is part of a safety function, there is a particular failure mode that has no effect on a safety function. This failure mode is called 'No effect'. This paper presents a method to calculate a DSP (Digital Signal Processor) board failure rate and failure mode data using an FMEDA (Failure Modes Effects and Diagnostic Analysis)

  11. 运用失效模式效应分析降低不合格检验标本的发生率%Reducing the happen rate of unquaHfied laboratory specimen by using Failure Mode Effect Analysis

    Institute of Scientific and Technical Information of China (English)

    黄忠琴

    2008-01-01

    Objective To perfact the procedure of specimen acquaring and transfering so as to reduce the happen rate of unqualified laboratory specimen.Methods The relative factors in the procedure of specimen acquaring and transfering were analysed by using Failure Mode Effect Analysis(FMEA)so that the preventative emphases could be based on the caculated Risk Priority Number(RPN)and rectifying measurements could be adopted according to the existing problems.Results The RPNs of unqualified laboratory specimen were reduced from 1 476 in the January of 2007 to 1 196 in the May of 2007,among them the prominent reducing RPN was 936in the March of 2007 and the happen rates of unqualified laboratory specimen were reduced accordingly.Conclusion FMEA is an effective rask management method by reducing the happen rate of unqualified laboratory specimen.%目的 完善检验标本采集和送检流程,降低不合格检验标本的发生率.方法 应用失效模式效应分析(Failure Mode Effect Analysis,FMEA)对标本采集及送检各个流程中的相关因数进行分析,计算出事件发生的RPN值(Risk Priority Number),并根据RPN值的大小确定预防的重点,针对存在的问题及时进行整改.结果 发生不合格检验标本的RPN值由2007年1月的1 476,降低到2007年5月的1 196,其中2007年3月达到936,为最低点,标本的不合格率相应降低.结论 使用FMEA有效地降低了送检标本的不合格率,是一种行之有效的风险管理方法.

  12. 醇酸树脂反应釜的失效模式及其影响分析%The Failure Mode and Effects Analysis of Alkyd Reaction Kettle

    Institute of Scientific and Technical Information of China (English)

    舒宜; 宋文华; 刘畅

    2009-01-01

    This article introduces the definition and classification of FMEA,and concludes the steps of analysis. A preliminary discussion of quantitative criteria of FMEA has been put forward. This article introduces the function of each component of the alkyd reaction kettle, and according to the basic principles of failure mode and effects analysis and based on the specific situation of alkyd production, author discussed the potential failure modes of the alkyd reaction kettle .consequences of it could lead to and causes. Based on quantitative criteria of severity and occurrence and detection degrees and RPN value,author carried out quantitative analysis to each object,and give suggestions to the one which exceeded the standard. FMEA method for the alkyd resin in the reactor to make up for the current application would greatly endanger the existence of a comprehensive identification and analysis, and provide useful information and data to guide the production. It will provide strong data support to protect the safety of production,the development of the maintenance repair for decision-making and optimize the costeffectiveness ratio.%本文介绍了失效模式及其影响分析的定义、分类及基本构成,并概括了其分析步骤.文中介绍了醇酸树脂反应釜各部件的功能,讨论了醇酸树脂反应釜的潜在失效模式、可能导致的后果及其原因;依据严重度、频度数、不易探测度及风险顺序值的量化标准,对各个项目进行了量化分析,对超出标准的项目提出了整改措施.对于FMEA方法 在醇酸树脂反应釜中的应用会大大弥补当前存在的危害进行全面的识别和分析,并提供有效的信息和数据指导生产,能够为保障安全生产、制定维护维修决策以及优化成本效益比率提供强有力的数据支持.

  13. Predicting Failures in Power Grids

    CERN Document Server

    Chertkov, Michael; Stepanov, Mikhail G

    2010-01-01

    Here we develop an approach to predict power grid weak points, and specifically to efficiently identify the most probable failure modes in load distribution for a given power network. This approach is applied to two examples: Guam's power system and also the IEEE RTS-96 system, both modeled within the static Direct Current power flow model. Our algorithm is a power network adaption of the worst configuration heuristics, originally developed to study low probability events in physics and failures in error-correction. One finding is that, if the normal operational mode of the grid is sufficiently healthy, the failure modes, also called instantons, are sufficiently sparse, i.e. the failures are caused by load fluctuations at only a few buses. The technique is useful for discovering weak links which are saturated at the instantons. It can also identify overutilized and underutilized generators, thus providing predictive capability for improving the reliability of any power network.

  14. Head Position and Internally Headed Relative Clauses.

    Science.gov (United States)

    Basilico, David

    1996-01-01

    Examines "Head Movement" in internally headed relative clauses (IHRCs). The article shows that in some cases, head movement to an external position need not take place and demonstrates that this movement of the head to a sentence-internal position results from the quantificational nature of IHRCs and Diesing's mapping hypothesis (1990, 1992). (56…

  15. Diagnosis of Equipment Failures by Pattern Recognition

    DEFF Research Database (Denmark)

    Pau, L. F.

    1974-01-01

    The main problems in relation to automatic fault finding and diagnosis in equipments or production systems are discussed: 1) compression of the syndrome and observation spaces for better discrimination between failure modes; 2) simultaneous display of the failure patterns and the failure instants...

  16. ANALYSIS OF CROSS-SECTIONAL FAILURE MODES OF RECYCLED AGGREGATE CONCRETE FLEXURAL FATIGUE TEST%再生混凝土抗折疲劳试验断面破坏形态分析∗

    Institute of Scientific and Technical Information of China (English)

    朱红兵; 许永强; 夏博; 张尧

    2016-01-01

    根据不同再生骨料取代率的再生混凝土在反复荷载作用下的断面破坏形态,分析影响再生混凝土抗折强度、抗折疲劳寿命的材料因素。对再生骨料取代率为0、30%、50%、70%的再生混凝土进行抗折强度试验以及应力水平为0�6、0�7、0�8的抗折疲劳试验。断面破坏形式表明:随着再生骨料取代率的提高,再生混凝土抗折强度越来越小,疲劳寿命逐渐降低,断面的两种破坏形式(骨料与砂浆之间的黏结破坏、骨料断裂破坏)的面积均呈线性递减趋势。为降低试件中再生集料附近区域产生应力集中的几率,建议生产再生混凝土时采取提高再生骨料强度、优化再生骨料加工工艺、增强再生粗骨料与砂浆之间的黏结等措施。%Based on the recycled concrete ( different recycled aggregate replacement ratio) specimen’ s damage mode under repeated loads, the material factors which can influence recycled concrete flexural strength, flexural fatigue life can be analyzed. Recycled concrete specimens of 0, 30%, 50%, 70% regeneration replacement⁃rate were poured, and flexural strength tests performed as well as the flexural fatigue test with stress level being 0�6,0�7,0�8. Cross⁃sectional failure morphology showed that with the increasing of recycled aggregate rate, recycled concrete’ s flexural strength became smaller, and the fatigue life decreased, the section area of two kinds of failure modes ( the bond failure between aggregate and mortar,aggregate fracture) showed a linear decreasing trend. To reduce the probability stress concentration around the recycled aggregate, it was recommended that the strength of recycled aggregate should be improved, recycled aggregate processing technology be optimized and the bonding between the recycled coarse aggregate and mortar be enhanced etc during the production of recycled concrete.

  17. Systems failure.

    OpenAIRE

    Macleod, Anna

    1998-01-01

    Systems Failure A solo exhibition of new work by Anna Macleod developed in conversation with curator Liz Burns. The Dock, Carrick on Shannon, Co Leitrim. Ireland. 12th February – 17th April 2010. The works for the exhibition Systems Failure include drawings, prints and small constructions that examine the delicate balance that exists between need and aspects of failure rooted in the relationship between humanity and land use. The work seeks to question the relationship between scient...

  18. Deriving Function-failure Similarity Information for Failure-free Rotorcraft Component Design

    Science.gov (United States)

    Roberts, Rory A.; Stone, Robert B.; Tumer, Irem Y.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Performance and safety are the top concerns of high-risk aerospace applications at NASA. Eliminating or reducing performance and safety problems can be achieved with a thorough understanding of potential failure modes in the design that lead to these problems. The majority of techniques use prior knowledge and experience as well as Failure Modes and Effects as methods to determine potential failure modes of aircraft. The aircraft design needs to be passed through a general technique to ensure that every potential failure mode is considered, while avoiding spending time on improbable failure modes. In this work, this is accomplished by mapping failure modes to certain components, which are described by their functionality. In turn, the failure modes are then linked to the basic functions that are carried within the components of the aircraft. Using the technique proposed in this paper, designers can examine the basic functions, and select appropriate analyses to eliminate or design out the potential failure modes. This method was previously applied to a simple rotating machine test rig with basic functions that are common to a rotorcraft. In this paper, this technique is applied to the engine and power train of a rotorcraft, using failures and functions obtained from accident reports and engineering drawings.

  19. Research on characteristics of multi-primary permanent magnet linear synchronous motors under switching failure modes%多定子永磁直线同步电机绕组切换故障特性研究

    Institute of Scientific and Technical Information of China (English)

    张宏伟; 余发山; 王新环; 王福忠

    2015-01-01

    针对多定子永磁直线同步电机(PMLSM)运行过程中绕组切换故障可能引起的失步问题,研究了绕组切换故障特性。在分析 PMLSM 推力功角特性的基础上,研究了频率对稳定运行区间的影响规律,建立了考虑出入端效应的多定子 PMLSM 推力模型,研究了绕组切换故障对稳定性的影响规律,利用样机进行了实验研究,得到了一台及两台绕组切换故障时,电机运行频率、运行方式对运行特性的影响规律。研究结果表明:低速 PMLSM 的电阻效应不能忽略,动子所受正向推力作用空间变小,负向推力作用空间增大。相同数量的绕组失电,提升运行时较易失步。失电绕组越多,剩余电机承担电流越大,越易引起失步。%Since the windings of multi-primary permanent magnet linear synchronous motor ( PMLSM) switching failure may cause motor lose step, characteristics of windings switching failure was researched. On the analysis of thrust power angle characteristic of PMLSM, the influence of frequency on stable oper-ation area was researched. The thrust model with entry and exit effect of multi-primary PMLSM was con-structed and the influence of windings switching failure on stable characteristic was researched. A multi-primary PMLSM prototype was applied to experiments. The influence of motor operating frequency and operation mode on running characteristics was obtained when one or two primary windings switching fails. The research results show that the impact of primary resistance is not negligible when the operating fre-quency of PMLSM is low. The forward thrust stable operation region is reduced and downward stable op-eration region is increased. If the stator windings switch failed when going upward, the motor is easy to out of step. The more number of switching failure windings is, the greater current of residual windings is, and the easier of the PMLSM is out of step.

  20. Strength and failure modes of ceramic multilayers

    DEFF Research Database (Denmark)

    Sørensen, Bent F.; Toftegaard, Helmuth Langmaack; Linderoth, Søren

    2012-01-01

    A model was developed for the prediction of the tensile strength of thin, symmetric 3-layer sandwich specimens. The model predictions rationalize the effect of heat-treatment temperature on the strength of sandwich specimens consisting of an YSZ (Yttria-Stabilized Zirconia) substrate coated...... and propagating into the substrate. These predictions are consistent with microstructural observations of the fracture surfaces. A good agreement was found between the measured strength values and model predictions. © 2012 Elsevier Ltd. All rights reserved....

  1. Analysis on the influence of thruster failure mode for a mooring assisted dynamic positioning system%锚泊辅助动力定位系统推力器故障模式影响分析

    Institute of Scientific and Technical Information of China (English)

    王洪超; 王磊; 张峰

    2013-01-01

    Mooring assisted dynamic positioning system is a new positioning system including mooring system and dynamic positioning system. With a certain deep water semi-submersible drilling platform as its subject, this paper is dedicated to exploring the influence of two thrusters' failure mode on the offset, power consumption and top tension of the mooring line of the platform using time domain simulation method. The results indicate that two thrusters' failure of the same switchboard may cause a remarkable impact on the offset of the platform. Thus, it is suggested that the forbidden angle of the thrusters adjacent to the failed thrusters should be cancelled, weather mooring lines be tightened and leeward mooring lines be loosed. The suggestion can reduce the offset and consumed power of the platform and may be helpful to the FMEA of dynamic positioning system.%锚泊辅助动力定位是将锚泊定位和动力定位相结合的一种新型位置控制系统.以某深水半潜式钻井平台为例,通过时域模拟分析了两个推力器失效模式对平台锚泊辅助动力定位系统定位精度、功率消耗及缆绳张力的影响.分析结果可以看出,深水作业时平台同一配电板上两推力器失效对平台水平偏移有很大影响,可通过减小或取消失效推力器相邻推力器的禁止角及拉紧迎风缆并松弛背风缆的方法来减小平台偏移,节约功耗,为动力定位系统的故障模式与影响分析提供了参考.

  2. Experimental investigations of hexagonal crimping die failure

    Directory of Open Access Journals (Sweden)

    Veera kumar M

    2016-06-01

    Full Text Available This paper deals with the hexagonal crimping die failure of high carbon high chromium steel material. The failure modes were initially revealed and identified by the visual examination. Then the chemical analysis and metallographic examination havebeen carried at different positions of the failure die surface using scanning electron microscope (SEM. The microstructure evaluation reveals that failure occurs due to undissolved austenitic structure resulting in improper transition duringheat treatment.

  3. 基于失效模式与效应分析管理模式构建导尿管相关尿路感染干预策略的研究%The research of building catheter-associated urinary tract infections intervention stratagem based on failure mode and effects analysis

    Institute of Scientific and Technical Information of China (English)

    张悦; 夏玲; 谭思源; 陈艳; 胡清; 金勤; 王卉洁; 韦佳佳

    2014-01-01

    Objective To build catheter-associated urinary tract infections intervention stratagem based on failure mode and effects analysis.Methods Based on failure mode and effects analysis,forming teams,drawing the flowchart,listing the failure mode,analyzing the causes and effects of failure mode,and the experts giving RPN score,and the score>125 should be given intervention stratagem.Results The value>125 included:operator preparation,insertion of catheters,fixing the collection bags,changing the urine collection bag,target monitoring and extubation.The eight improvement program was built.Conclusions To build catheter-associated urinary tract infections intervention stratagem based on failure mode and effects analysis is feasible and scientific,there are certain clinical application prospect.%目的 基于失效模式与效应分析(failure mode and effects analysis,FMEA)管理模式构建导尿管相关尿路感染干预策略.方法 基于FMEA管理模式,组建团队、绘制流程图、识别流程中潜在失效模式、分析失效原因及影响因素、进行风险优先指数(RPT)评分,对评分>125分的失效模式构建干预策略.结果 RPN评分>125分的失效模式有8个,即操作者准备、插入导尿管、固定集尿袋、会阴护理、集尿袋放尿、更换集尿袋、目标监测及拔管.对8个失效模式构建干预策略.结论 基于FMEA管理模式构建导尿管相关尿路感染干预策略是可行的、科学的,具有一定的临床应用价值及前景.

  4. Is HEADS in our heads?

    DEFF Research Database (Denmark)

    Boisen, Kirsten A; Hertz, Pernille Grarup; Blix, Charlotte

    2016-01-01

    BACKGROUND: Outpatient clinic visits are a window of opportunity to address health risk behaviors and promote a healthier lifestyle among young people. The HEADS (Home, Education, Eating, Activities, Drugs [i.e. substance use including tobacco, alcohol, and illegal drugs], Sexuality [including...... care professionals participated. We found only small reported differences between staff and young patients regarding whether home, education, and activity were addressed. However, staff reported twice the rate of addressing smoking, alcohol, illegal drugs, sexuality, and contraception compared to young...... patients. Young patients reported that smoking, alcohol, illegal drugs, sexuality, and contraception were addressed significantly more at adult clinics in comparison to pediatric clinics. After controlling for age, gender and duration of illness, according to young patients, adjusted odds ratios...

  5. 左束支阻滞激动模式:心功能不良重要的可逆性因素%The exaitation mode of left bundle branch block:an important reversible factor of heart failure

    Institute of Scientific and Technical Information of China (English)

    单其俊; 邹建刚; 陈椿; 杨兵; 陈明龙; 徐东杰; 侯小峰; 曹克将

    2009-01-01

    目的 观察左束支阻滞激动模式对心脏功能和结构的影响.方法 3例心功能不良和左心室扩大患者,左心室射血分数(LVEF)0.44 ±0.11,左心室舒张末内径(LVEDD)(56±4)mm,QRS时限增宽(177±15)ms,呈左束支阻滞或左束支阻滞样图形.例1为风湿性心脏病二尖瓣及主动脉瓣置换术后伴左束支阻滞;例2为显性右侧预激综合征;例3 24 h动态心电图示右心室流出道室性早搏(室早)3万次.结果 例1成功行心脏再同步治疗,例2和例3成功行右侧显性旁路和右心室流出道室早消融,QRS时限降至(103±25)ms,随访6~30个月,症状明显改善,心功能恢复正常,左心室明显缩小,LVEF为0.65 ±0.04和LVEDD(48±4)mm.结论 左束支阻滞激动模式是心功能不良重要的可逆性因素.%Objective To investigate the effects of excitation mode of left bundle branch block (LBBB) or LBBB-like on the cardiac function and structure.Methods This study included three patients with depressing cardiac function (LVEF=0.44±0.11 ) and enlarged left ventricle [LVEDD=(56+4)mm).The widen QRS complex (QRS duration=(177±15 )ms] displayed LBBB or LBBB-like was documented in all patients.One patient with serious heart failure had the history of surgical mitral and aortic valves replacement and LBBB.The right ventricular preexcitation and frequent premature ventricular contractions ( more than 30 000 beats per 24 hours) were documented in other 2 patients,respectively.Results The patient with surgical valves replacement and LBBB underwent successful cardiac resynchrunization therapy with biventricular pacing.The para-Hisian accessory pathway and premature ventricular contractions originated from right ventricular outflow tract were ablated successfully in other patients,respectively.After the procedures,the QRS complex became significant narrow [QRS duration=(103±25)ms) in all patients.During the follow-up period of 6 to 30 months,the cardiac function ( LVEF=0.65±0

  6. 热老化对核电厂一回路主管道LBB分析失效模式的影响%Study of Influence of Thermal Aging on Failure Mode of Primary Water Pipes in LBB Analysis

    Institute of Scientific and Technical Information of China (English)

    陈明亚; 王荣山; 余炜伟; 尤磊; 甄洪栋; 吕峰; 薛飞

    2015-01-01

    核电厂一回路主管道的材料热老化对其"未爆先漏"( LBB)分析存在明显的影响,基于美国NUREG/CR 4513报告,分析了热老化对一回路主管道的结构塑性极限载荷、裂纹扩展稳定性图( J-T图)、弹塑性断裂失效( EPFM)临界裂纹尺寸和结构失效模式的影响. 案例分析结果表明,热老化增加了材料的流变应力和结构塑性极限载荷(增加了11 .78%)、降低了材料韧性(裂纹扩张量为5 mm时下降了62 .65%)、同样的撕裂模量下热老化后允许的J积分降低了50%以上,热老化后结构的塑性极限载荷与EPFM极限载荷之比(对应于ASME规范Ⅺ卷的Z因子)明显增大. 研究结果还表明,在较大的外部载荷作用下,J-T图的驱动力曲线不再是条直线,这与诸如ASME规范Ⅺ卷的简单分析假设不一致,采用ASME规范中的简单假设可能得到非精确的结论. 主管道既可能发生EPFM失效,又可能发生塑性失稳失效,发生EPFM失效对应的载荷区间更大.%There is an obvious effect on the analysis of leak before break( LBB) for thermal aging of the primary water pipes.In this paper,based on the information in the report of NUREG/CR 4513,the effects of thermal aging on the plastic limit load,stability assessment diagram( J-T diagram) ,critical crack size of the elastic-plastic fracture and the failure mode are analyzed.The results of the case study show that, the thermal aging increases the flow stress and the plastic limit load(increased by 11.78%),decreases the material toughness( decreased by 62.65%when the crack extension is 5 mm) ,and the allowed J inte-gral was decreased half at the same tearing modulus.The Z factor in the ASME code will be increased sig-nificantly.Sometimes, the driving force curve is not a straight line which is not consistent with the assumption in the ASME code .The failure mode may be either the elastic plastic fracture or plastic collapse ,and the elastic plastic fracture relates to larger

  7. PEDIATRIC HEAD INJURIES, MECHANISM TO MANAGEMENT: EXPERIENCE OF A SINGLE CENTER

    Directory of Open Access Journals (Sweden)

    Pankaj

    2016-01-01

    Full Text Available INTRODUCTION Head injury is very common in modern life. Patients of any age group may have head injury however mechanism of head injury, pathophysiology and outcome of head injury is quite different in adults as compared to children. Road traffic accident is a common mode of head injury in adults while fall from height and household abuse is common mode in children. In Western countries, there is a separate registry system for pediatric head injury but there is no such system exist in india. Our present study is focused on pediatric head injury and evaluation of factors that affect the final outcome in pediatric patients.

  8. Static and cyclic pullout behavior of cast-in-place headed and bonded anchors with large embedment depths in cracked concrete

    Energy Technology Data Exchange (ETDEWEB)

    Delhomme, F., E-mail: fabien.delhomme@insa-lyon.fr [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France); Roure, T.; Arrieta, B. [EDF SEPTEN Compagny, Civil Engineering, Villeurbanne (France); Limam, A. [University of Lyon, INSA-Lyon, LGCIE, F-69621 Villeurbanne (France)

    2015-06-15

    Highlights: • Optimizing the design and identifying margin of the headed fasteners used in French nuclear power plants. • Static and cyclic pullout tests on cast in place anchorage composed of an anchor plate welded to four headed or bonded rods. • Experimental data base on tests on anchor plates. • Anchor with large embedment depths in cracked concrete. • Edge effects. - Abstract: The equipment of French nuclear power plants is fixed on reinforced concrete structures with base plate with headed fasteners. EDF decided to carry out an experimental research program in partnership with LGCIE in order to optimize the design of the headed fasteners and identify margin. This article introduces the results of pullout tests on anchors with large embedment cast in place in a reinforced concrete block. The anchorage are composed of an anchor plate welded to four ribbed bars or headed smooth studs. The studied parameters are: the type of loading (static or cyclic), the edge distance, the state of cracking of the concrete block. The anchors with headed rods or ribbed bars have a steel rod failure mode in agreement with their initial design. However, an optimization of the size on the headed anchors seems to be expected in order to improve their installation. This experimental campaign will provide a data base enabling the development of numerical models in order to improve the design.

  9. 爆炸作用下钢筋混凝土柱非线性动力响应及破坏模式影响因素分析%Analysis on nonlinear dynamic responses and failure modes of RC columns under blast loads

    Institute of Scientific and Technical Information of China (English)

    方秦; 程国亮; 陈力

    2012-01-01

    The purpose of this paper is to predict dynamic responses and failure modes of RC columns subjected to blast loads.In this paper,the three failure criteria corresponding to the typical flexure failure,diagonal shear failure and direct shear failure were firstly presented.And an effective approach to predict the dynamic responses and failure modes of blast-loaded RC columns was established,incorporating the explicit finite difference method proposed in the reference [1] with the failure criteria.The effects of the blast loading(peak pressure,duration and intensity distribution on RC columns),cross-sectional resistance(bending capacity and shear capacity),axial loads and length on the responses and failure modes of RC columns were analyzed and discussed.It is demonstrated that the blast-loaded RC columns may suffer from typical flexure failure,diagonal shear failure and direct shear failure,just like RC beams.However,the diagonal shear failure is the most frequently observed.The shorter the loading duration is,the higher the peak value becomes.The weaker sectional shear capacityis,the more vulnerable to diagonal shear failure and even direct shear failure RC columns is.And the greater axial force,the longer column length,the more vulnerable to bending failure RC columns was.%为研究RC柱在爆炸作用下动力响应及破坏模式,在文献[1]建立的爆炸作用下RC柱非线性响应的有限差分分析方法基础上,提出了RC柱在爆炸作用下弯曲、斜剪、直剪等破坏模式的判别准则,建立了RC柱在爆炸作用下破坏模式的分析方法,分析了爆炸作用(峰值、作用时间及其沿柱上分布形式)、截面抗力(受弯能力、受剪能力)、轴力、柱长等对RC柱破坏模式的影响特点及规律。研究表明:在爆炸作用下,RC柱会发生与RC梁一样的弯曲破坏、斜剪破坏、直剪破坏等3种典型破坏模式,但主要以斜剪破坏为主;爆炸作用时间越短,峰值越高,柱截面

  10. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a ... of page What are some common uses of the procedure? CT scanning of the head is typically ...

  11. Computed Tomography (CT) -- Head

    Medline Plus

    Full Text Available ... of the Head? What is CT Scanning of the Head? Computed tomography, more commonly known as a ... of page What are some common uses of the procedure? CT scanning of the head is typically ...

  12. Plug shear failure in nailed timber connections:avoiding brittle and promoting ductile failures

    OpenAIRE

    Johnsson, Helena

    2004-01-01

    Mechanical timber connections can fail both in a brittle and a ductile manner depending on the joint layout. Plug shear failure in nailed timber connections is a brittle failure mode, which shall be avoided in timber structures. This failure mode occurs in nailed connections loaded in tension parallel to the grain, for instance in the lower chord of a timber truss. The failure mode is not described in the Swedish building code of today, but there is an informative annex in the upcoming Euroco...

  13. Head Impact Laboratory (HIL)

    Data.gov (United States)

    Federal Laboratory Consortium — The HIL uses testing devices to evaluate vehicle interior energy attenuating (EA) technologies for mitigating head injuries resulting from head impacts during mine/...

  14. Failure mode research on CCF300 and T300 carbon fiber composite laminates with delamination under compressive strength%含分层损伤国产碳纤维CCF300与T300碳纤维复合材料层合板压缩失效模式

    Institute of Scientific and Technical Information of China (English)

    傅惠民; 杨雨松; 张勇波

    2011-01-01

    The compression test was conducted on the homemade and T300 carbon fiber composite laminate with one delamination.According to the macro-shape and the ultrasonic C-scan result of post-failure specimens which contain different sizes and different positions of delaminations but the same thickness,an investigation has been conducted by this study on the effects of delmaination sizes and positions on the failure mechanism of homemade and T300 carbon fiber composite laminates.Also the differences of failure mode have been analyzed between these two kinds of composites.The final result shows that the imbedded delaminations have all propagated,and the position of delamination proposed to be the most important factors affecting the compressive failure mode.To the laminates with deep delamination the failure mode presented to be the first propagation of delamination and second shear buckling failure of sub-laminate.Based on these analyses we find that the failure mode of homemade carbon fiber composite is same with the T300 carbon fiber composite generally.%对含单个分层损伤国产碳纤维CCF300与T300碳纤维复合材料层合板进行压缩试验,通过对同种中等厚度含不同分层大小、不同分层位置的层合板压缩失效后的宏微形貌及超声波C扫描检测结果的分析,研究了分层大小及分层位置对于国产碳纤维及T300纤维复合材料层合板失效模式造成的影响,比较了两种纤维复合材料失效模式的异同.结果表明,预制分层在压缩过程中都发生了扩展,而分层位置是影响其压缩失效模式较为重要的因素.对于分层位置较深的层合板,其失效模式往往为首先发生分层扩展,进而子层板剪切屈曲失效.总的分析表明,国产碳纤维复合材料与T300纤维复合材料含分层损伤层合板的压缩失效模式基本相同.

  15. Heart failure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    2008275 Relationship of calcineure in mRNA level in peripheral blood and cardiac muscle of patients with heart failure.WANG Mengmeng(王萌萌),et al.Dept Cardiol,Shandong Prov Hosp,Shandong Univ,Jinan 250021.Chin Cir J 2008;23(2):113-116.Objective To study the relationship of calcineurin mRNA level between peripheral lymphocytes and cardiac muscles of patients with chronic heart failure.Methods

  16. Heart failure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    2008037 Factors associated with efficacy of cardiac resynchronization therapy for patients with congestive heart failure. SHI Haoying(史浩颖), et al. Dept Cardiol, Zhongshan Hosp Fudan Univ, Shanghai 200032. Chin J Cardiol 2007;35(12):1099-1163. Objective The efficacy of cardiac resynchronization therapy (CRT) in patients with congestive heart failure and the potential factors associated with responder or nonresponder were investigated. Methods Fifty

  17. Application of healthcare failure mode and effect analysis in hospital transport of critically ill patients in emergency department%医疗失效模式与效应分析在急诊危重患者院内转运中的应用

    Institute of Scientific and Technical Information of China (English)

    王宁

    2013-01-01

    Objective To explore the application of healthcare failure mode and effect analysis in hospital transport of critically ill patients in emergency department. Methods Healthcare failure mode and effect analysis were used to analyze the influencing factors of hospital transport of critically ill patients in e-mergency department. Failure mode was found from 3 processes of pre - transport,in transit and after - transport,and the control schemes were developed pertinently. Results The incidence of adverse events in transport was reduced, and the handover problems were reduced ( P < 0. 01 or P < 0.05 ). Conclusion Application of healthcare failure mode and effect analysis can improve the safety of hospital transport of critically ill patients in emergency department.%目的 探讨医疗失效模式与效应分析在急诊危重患者转运中的应用.方法 运用医疗失效模式与效应分析院内安全转运的影响因素,从转运前、转运中及转运后3个流程查找失效模式,并有针对性地制订控制方案.结果 降低了院内患者转运中意外的发生率,减少了与接收科室发生的交接问题(P<0.01或P<0.05).结论 应用医疗失效模式与效应分析可提高急诊危重患者院内转运的安全性.

  18. Heading and head injuries in soccer.

    Science.gov (United States)

    Kirkendall, D T; Jordan, S E; Garrett, W E

    2001-01-01

    In the world of sports, soccer is unique because of the purposeful use of the unprotected head for controlling and advancing the ball. This skill obviously places the player at risk of head injury and the game does carry some risk. Head injury can be a result of contact of the head with another head (or other body parts), ground, goal post, other unknown objects or even the ball. Such impacts can lead to contusions, fractures, eye injuries, concussions or even, in rare cases, death. Coaches, players, parents and physicians are rightly concerned about the risk of head injury in soccer. Current research shows that selected soccer players have some degree of cognitive dysfunction. It is important to determine the reasons behind such deficits. Purposeful heading has been blamed, but a closer look at the studies that focus on heading has revealed methodological concerns that question the validity of blaming purposeful heading of the ball. The player's history and age (did they play when the ball was leather and could absorb significant amounts of water), alcohol intake, drug intake, learning disabilities, concussion definition and control group use/composition are all factors that cloud the ability to blame purposeful heading. What does seem clear is that a player's history of concussive episodes is a more likely explanation for cognitive deficits. While it is likely that the subconcussive impact of purposeful heading is a doubtful factor in the noted deficits, it is unknown whether multiple subconcussive impacts might have some lingering effects. In addition, it is unknown whether the noted deficits have any affect on daily life. Proper instruction in the technique is critical because if the ball contacts an unprepared head (as in accidental head-ball contacts), the potential for serious injury is possible. To further our understanding of the relationship of heading, head injury and cognitive deficits, we need to: learn more about the actual impact of a ball on the

  19. Application of FMEA-DEA (Failure Modes and Effect Analysis - Data Envelopment Analysis) to the air conditioning system of the control room a nuclear power plant; Aplicacao de FMEA-DEA ao sistema de ar condicionado da sala de controle de uma usina nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Barbosa Junior, Gilberto Varanda

    2007-03-15

    This dissertation presents the FMEA-DEA analysis application to the air conditioning system of the control room of a nuclear power plant. After obtaining the failure modes, the index associated to the occurrence probability, the severity of the effects and the potential of detention, a priority order is established for the failure modes or deviations. This number is obtained by multiplying the three mentioned index that vary in a natural scale from 1 to 10, where the higher the index, the more critical the situation will be. In this work, it is intended to use a model based on the data envelopment analysis, DEA jointly with the FMEA, to identify the current efficiency of the system and which failure modes or deviations are considered more critical, and by means of the weights attributed for the mathematical modeling to identify which index are contributing more for these deviations. From this identification, improvements can be set, which may consider administrative changes, operator training and so on, thus adding value to the final product. (author)

  20. Reliability analysis for multiple failure modes related sliding stability system between layers of gravity dam%重力坝多失效模式相关层间抗滑稳定体系的可靠性分析

    Institute of Scientific and Technical Information of China (English)

    张社荣; 王超; 孙博

    2013-01-01

      提出了基于 Copula函数的重力坝多失效模式相关体系的可靠性分析方法。运用多元Copula函数建立了重力坝层间抗滑稳定相关体系的联合分布模型,从理论上推导了基于Copula函数求解体系相关可靠度的计算式;然后采用非参数估计方法确定了相应Copula函数中的待定参数。通过算例,验证了基于Copula函数的相关性可靠度分析模型的合理性,接着对某重力坝多失效模式相关的层间抗滑稳定体系进行了可靠性分析,并与传统方法的计算结果进行了对比。算例结果表明,Clayton Copula函数可以作为表征重力坝串联体系可靠性中失效模式间相关结构的最优Copula函数,基于Copula函数的相关性可靠度模型计算结果克服了基于独立性假设的一阶、二阶区间估计等方法的局限性,且仍在Ditlevsen二阶界限区间估计值的范围内,能够满足工程问题的精度要求。%System reliability analysis method for multiple failure patterns of gravity dam is put forward based on the Copula function. The joint distribution model is established using Copula function of stability between layers of gravity dam, and the computational formula of this system reliability analysis method is deduced theoretically. Then, the parameters in the Copula are determined using the parameter estimation method. The reasonableness of the reliability analysis model is verified through a case study,and then the related sliding stability system reliability between layers is analyzed and also compared with the calculation results of the traditional method. The results show that Clayton Copula function can be characterized as a series of gravity dam system reliability failure mode of the correlation between the optimal structure Copula function,based on the correlation of Copula function reliability model calculation results overcome the limi⁃tations of the first and second order interval

  1. School failure.

    Science.gov (United States)

    Dworkin, P H

    1989-04-01

    Numerous factors may contribute to a child's failure to learn. Certain causes of school failure, such as specific learning disabilities, mental retardation, sensory impairment, and chronic illness may be regarded as intrinsic characteristics of the child. Other causes, such as family dysfunction, social problems, and ineffective schooling, are characteristics of the child's environment. Still other influences on school performance, such as temperamental dysfunction, attention deficits, and emotional illness, may be viewed as the consequence of the interaction between the child and his or her environment. The reasons for a child's school failure must not be considered in isolation but rather within the context of social and environmental circumstances. Evaluation must consider the myriad of reasons for a child's school failure and attempt to identify "clusters" of adverse influences on school performance. Detailed information must be sought from the student, parents, and school system through the history and physical examination. Questionnaires are useful in data gathering. Ancillary methods of assessment that may be of value include neurodevelopmental screening and laboratory studies. Further investigations and referrals, particularly psychoeducational evaluation, are of major importance. Traditional roles of the pediatrician in school failure include the treatment of underlying medical conditions, counseling, the coordination of further investigations and referrals, and the facilitation of communication with community services and resources. Participation with other disciplines in the development of a child's educational plan is feasible and useful.

  2. Analyses of failure modes-based seismic fragility of gravity dams%基于破坏形态的重力坝地震易损性研究

    Institute of Scientific and Technical Information of China (English)

    钟红; 李晓燕; 林皋

    2012-01-01

    Seismic risk analysis is an effective method to evaluate and improve the seismic safety of dams.Seismic fragility analyses can describe the conditional probabilities of structural damage caused by different levels of earthquakes.It is one of three issues(seismic hazard analysis,seismic fragility analysis and seismic loss assessment) of seismic risk analyses.By considering meso-level influence of concrete heterogeneity,large amount of nonlinear time-history analyses of rolled compacted concrete gravity dam under strong earthquake are performed.Typical failure modes of gravity dam are concluded and a five-level standard for seismic damage of gravity dam is put forward.Combined with non-exceedance probabililty of design earthquake for the dam,the seismic fragility curve for retaining dam section of Jin'anqiao dam is obtained.This research is helpful to optimize seismic design,reinforcement and maintenance measures and improve aseismic capability of the dam.%大坝的地震风险分析是评价和改进大坝抗震安全度的有效工具.大坝的地震易损性是指大坝在给定地震荷载作用下发生各级损伤的条件概率,是地震风险研究(地震危险性分析、地震易损性分析、地震灾害损失评估)的3个主要组成部分之一.在考虑混凝土材料细观层次非均匀性影响的基础上,通过对碾压混凝土重力坝强震损伤破坏形态和过程的大量数值模拟,总结提炼了重力坝的典型震害形态,并据此提出了重力坝的五级震害等级划分标准.结合大坝设计地震超越概率,提出了大坝易损性分析方法,给出了金安桥重力坝挡水坝段的地震易损性曲线.研究结果可为混凝土重力坝的抗震设计和加固决策等提供参考.

  3. 冷成型轴压方钢管柱破坏模式的数值模拟研究%NUMERICAL SIMULATION OF THE FAILURE MODES FOR COLD-FORMED SQUARE HOLLOW SECTION STEEL COMPRESSION COLUMNS

    Institute of Scientific and Technical Information of China (English)

    马成; 叶继红

    2009-01-01

    Ultimate bearing capacity and failure modes of cold-formed square hollow section steel compression columns are studied by numerical simulation,and comparisons of experimental results are made to reveal the whole process correctly. Material nonlinearity is considered in the analysis, as well as geometric nonlinearity. The issues that needed to be mentioned in cold-formed compression members modeling by ANSYS are elaborated, and the influences of parameters such as grid density and initial imperfection on simulation are investigated according to the results of numerical simulation. The reasonable finite element model, meshing and the applying method of initial imperfection are proposed. The results of numerical simulation are in good agree with the experimental results. The suggestions of simulating the boundary conditions of the columns in practical engineering are also given.%为准确揭示冷成型轴压方钢管柱的受力全过程,对其极限承载力和破坏模式进行了数值模拟研究,并与试验结果进行了对比.分析中考虑了材料非线性和几何非线性的影响.详细阐述了使用ANSYS进行冷成型轴压方管柱建模时需要注意的问题,并根据模拟结果分析了网格密度、初始缺陷等参数对模拟效果的影响.提出了合理的有限元分析模型、网格划分密度,初始缺陷施加方式等一系列具体措施.数值模拟结果与试验结果吻合良好.给出了实际工程中拄边界条件模拟方法的建议.

  4. 基于XFEM的砼重力坝强震破坏模式及抗震安全评价%Seismic failure mode and safety evaluation for concrete gravity dams based on XFEM

    Institute of Scientific and Technical Information of China (English)

    张社荣; 王高辉; 庞博慧; 严磊

    2012-01-01

    扩展有限元法(XFEM)通过在相关节点的影响域上富集非连续位移模式,使对非连续位移场的表征独立于单元边界,可有效描述混凝土中裂纹扩展.采用XFEM对Koyna重力坝地震破坏过程进行分析,结果表明,大坝开裂破坏分布与Koyna大坝实际破坏情况及文献中的模型试验结果相符,验证计算模型的有效性.将其应用到国内某混凝土重力坝,得到强震作用下动力响应及破坏模式,并据此评价大坝抗震安全性及抗震超载潜能.研究表明,强震作用下,大坝首先在下游折坡出现裂缝并扩展至上游面形成贯穿性裂缝,同时在坝踵、上游坡度变化处出现开裂破坏;该重力坝在设计地震作用下,尚有1.59 ~1.76倍的超载裕度,其抗震安全性能满足设计要求.%The extended finite element method (XFEM ) can make the characterization of discontinuous displacement field independent upon element boundaries through enriching discontinuous displacement mode in the influence domain of related nodes. With this capacity, XFEM can effectively describe the crack propagation in concrete. Here, the damaged process of Koyna gravity dam during earthquake was analyzed with XFEM, the distribution of cracking damage was consistent with the actual condition and the model test results in literatures, it verified the validity of the XFEM calculation model. Then, this technique was used to analyze a domestic concrete gravity dam, and its dynamic response and failure mode during strong earthquake were obtained. Based on these results, the seismic safety and overload potential of the dam were assessed. The results showed that cracks initially emerge at the change position in the downstream slope and then extend to the upstream surface of the dam to form penetrating cracks; at the same time, the dam heel and the change position in upstream slope are also prone to suffer cracking destruction; the overload margin of the concrete gravity dam under

  5. Respiratory failure

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    970318 A study on evoked potentials in cor pul-monale patients with chronic respiratory failure.QIAO Hui(乔慧), et al. Beijing Neurosurg Instit,Beijing, 100050. Chin J Geriatr 1997; 16(1): 43-45. Objective: Evoked protential was used to detect thechange of brain function in cor pulmonale patients with

  6. Heart failure

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    2009170 Curcumin attenuates left ventricular dysfunction and remodeling in rabbits with chronic heart failure. TANG Yanhong(唐艳红),et al.Dept Cardiol,Renmin Hosp,Wuhan Univ,Wuhan 430060.Chin J Cardiol,2009;37(3):262-267.

  7. Heart failure

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    2008411 Expression of S100B during heart failure in rats. JIANG Zhenni(蒋珍妮), et al. Dept Cardiol, 2nd Affili Hosp, Zhejiang Univ, Coll Med Hangzhou 310009. Chin J Emerg Med 2008;17(5):475-478. Objective To evaluate the value of S100B gene on cardiovascular remodeling in rats with abdominal aorta coarctation.

  8. Heart failure

    Institute of Scientific and Technical Information of China (English)

    1997-01-01

    970284 Effects of enalapril on heart rate variabilityin patients with congestive heart failure. ZHANGYouhua(章友华), et a1. Dept Cardiol, Cardiovasc Instit& Fuwai Hosp, CAMS & PUMC, Beijing, 100037. ChinCir J 1996; 11(2): 729-732.

  9. Research on seismic response and failure modes of system of transmitting boundary-soil-wind power structures%透射边界-地基-风电结构地震响应与破坏模式

    Institute of Scientific and Technical Information of China (English)

    柳国环; 练继建; 于通顺

    2014-01-01

    source wave motion and scattering force caused by endogenous oscillation are both considered. Analysis results show that: (1) the reason why force is used for seismic motion input in the model with transmitting boundary is clarified;and the method of seismic motion input is in accord with the actual situation;(2) a convenient method of the generation of stiffness force and damping force is proposed for the foundation of circular cross-section;and it can greatly reduce the workload;(3) the reason that dynamic response of offshore wind power structure is smaller using transmitting boundary than using fixed boundary is explained from the viewpoint of vibration characteristics of model and the damping; (4) the indispensability of endogenous oscillation in seismic response and failure modes of structure using transmitting boundary is pointed out.

  10. [Photodynamic therapy for head and neck cancer

    DEFF Research Database (Denmark)

    Lajer, C.B.; Specht, Lena; Kirkegaard, J.

    2006-01-01

    Photodynamic therapy (PDT) is a new treatment for head and neck cancer. The principle of the treatment is a photochemical reaction initiated by light activation of a photosensitizer, which causes the death of the exposed tissue. This article presents the modes of action of PDT and the techniques...

  11. Renal failure

    Institute of Scientific and Technical Information of China (English)

    1993-01-01

    930150 Epidermal growth factor and its recep-tor in the renal tissue of patients with acute re-nal failure and normal persons.LIU Zhihong(刘志红),et al.Jinling Hosp,Nanjing,210002.Natl Med J China 1992;72(10):593-595.Epidermal growth factor(EGF)and its receptor(EGF-R)were identified by immunohis-tochemical method(4 layer PAP)in the renaltissue specimens obtained from 11 normal kid-neys and 17 cases of acute renal failure(ARF).The quantitative EGF and EGF-R in the tissuewere expressed as positive tubules per mm~2.The amount of EGF and EGF-R in renal tissue