Science.gov

Sample records for aided failure analysis

  1. The failure analysis of composite material flight helmets as an aid in aircraft accident investigation.

    PubMed

    Caine, Y G; Bain-Ungerson, O; Schochat, I; Marom, G

    1991-06-01

    Understanding why a flying helmet fails to maintain its integrity during an accident can contribute to an understanding of the mechanism of injury and even of the accident itself. We performed a post-accident evaluation of failure modes in glass and aramid fibre-reinforced composite helmets. Optical and microscopic (SEM) techniques were employed to identify specific fracture mechanisms. They were correlated with the failure mode. Stress and energy levels were estimated from the damage extent. Damage could be resolved into distinct impact, flexure and compression components. Delamination was identified as a specific mode, dependent upon the matrix material and bonding between the layers. From the energy dissipated in specific fracture mechanisms we calculated the minimum total energy imparted to the helmet-head combination and the major injury vector (MIV) direction and magnitude. The level of protection provided by the helmet can also be estimated.

  2. Systematic Destruction of Electronic Parts for Aid in Electronic Failure Analysis

    NASA Technical Reports Server (NTRS)

    Decker, S. E.; Rolin, T. D.; McManus, P. D.

    2012-01-01

    NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. Operational amplifiers and transistors are two examples of EEE parts critical to NASA missions that can fail due to electrical overstress (EOS). EOS is the result of voltage or current over time conditions that exceeds a component s specification limit. The objective of this study was to provide known voltage pulses over well-defined time intervals to determine the type and extent of damage imparted to the device. The amount of current was not controlled but measured so that pulse energy was determined. The damage was ascertained electrically using curve trace plots and optically using various metallographic techniques. The resulting data can be used to build a database of physical evidence to compare to damaged components removed from flight avionics. The comparison will provide the avionics failure analyst necessary information about voltage and times that caused flight or test failures when no other electrical data is available.

  3. Liability for Failure To Provide AIDS Training.

    ERIC Educational Resources Information Center

    Smith, Michael R.

    1990-01-01

    The U.S. Constitution guarantees a right to privacy that requires deputies and jailers to avoid the unnecessary disclosure of sensitive information about a person. This privacy right especially covers Acquired Immune Deficiency Syndrome-related (AIDS) information, and it even protects the immediate family of persons infected with human…

  4. AIDS in an infant causing severe failure to thrive.

    PubMed

    Elias-Jones, A C; Larcher, V F; Price, E H

    1987-07-01

    A nine-month-old female Jamaican infant presented with a history of severe failure to thrive, recurrent pneumonia and developmental delay. She was found to have hepatosplenomegaly, generalised lymphadenopathy and hypotonia. Investigations revealed polyclonal hypergammaglobulinaemia, cytomegalovirus in her urine, and patchy lung infiltrates on her chest radiographs. Three separate tests were positive for human immunodeficiency virus in both the infant and her mother, suggesting vertical transmission, and confirming AIDS as the cause of the severe failure to thrive.

  5. Failure modes and effects analysis automation

    NASA Technical Reports Server (NTRS)

    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.

  6. Flight crew aiding for recovery from subsystem failures

    NASA Technical Reports Server (NTRS)

    Hudlicka, E.; Corker, K.; Schudy, R.; Baron, Sheldon

    1990-01-01

    Some of the conceptual issues associated with pilot aiding systems are discussed and an implementation of one component of such an aiding system is described. It is essential that the format and content of the information the aiding system presents to the crew be compatible with the crew's mental models of the task. It is proposed that in order to cooperate effectively, both the aiding system and the flight crew should have consistent information processing models, especially at the point of interface. A general information processing strategy, developed by Rasmussen, was selected to serve as the bridge between the human and aiding system's information processes. The development and implementation of a model-based situation assessment and response generation system for commercial transport aircraft are described. The current implementation is a prototype which concentrates on engine and control surface failure situations and consequent flight emergencies. The aiding system, termed Recovery Recommendation System (RECORS), uses a causal model of the relevant subset of the flight domain to simulate the effects of these failures and to generate appropriate responses, given the current aircraft state and the constraints of the current flight phase. Since detailed information about the aircraft state may not always be available, the model represents the domain at varying levels of abstraction and uses the less detailed abstraction levels to make inferences when exact information is not available. The structure of this model is described in detail.

  7. When Summative Computer-Aided Assessments Go Wrong: Disaster Recovery after a Major Failure

    ERIC Educational Resources Information Center

    Harwood, Ian

    2005-01-01

    This case study outlines the events of a recent summative computer-aided assessment (CAA) failure involving 280 first-year undergraduate students. Post-test analysis found that the central server had become unexpectedly overloaded, thereby causing the CAA to be abandoned. Practical advice on just what to do in the event of a summative CAA failure…

  8. BIOASSAY VESSEL FAILURE ANALYSIS

    SciTech Connect

    Vormelker, P

    2008-09-22

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

  9. Failure environment analysis tool applications

    NASA Technical Reports Server (NTRS)

    Pack, Ginger L.; Wadsworth, David B.

    1994-01-01

    Understanding risks and avoiding failure are daily concerns for the women and men of NASA. Although NASA's mission propels us to push the limits of technology, and though the risks are considerable, the NASA community has instilled within it, the determination to preserve the integrity of the systems upon which our mission and, our employees lives and well-being depend. One of the ways this is being done is by expanding and improving the tools used to perform risk assessment. The Failure Environment Analysis Tool (FEAT) was developed to help engineers and analysts more thoroughly and reliably conduct risk assessment and failure analysis. FEAT accomplishes this by providing answers to questions regarding what might have caused a particular failure; or, conversely, what effect the occurrence of a failure might have on an entire system. Additionally, FEAT can determine what common causes could have resulted in other combinations of failures. FEAT will even help determine the vulnerability of a system to failures, in light of reduced capability. FEAT also is useful in training personnel who must develop an understanding of particular systems. FEAT facilitates training on system behavior, by providing an automated environment in which to conduct 'what-if' evaluation. These types of analyses make FEAT a valuable tool for engineers and operations personnel in the design, analysis, and operation of NASA space systems.

  10. Failure environment analysis tool applications

    NASA Technical Reports Server (NTRS)

    Pack, Ginger L.; Wadsworth, David B.

    1993-01-01

    Understanding risks and avoiding failure are daily concerns for the women and men of NASA. Although NASA's mission propels us to push the limits of technology, and though the risks are considerable, the NASA community has instilled within, the determination to preserve the integrity of the systems upon which our mission and, our employees lives and well-being depend. One of the ways this is being done is by expanding and improving the tools used to perform risk assessment. The Failure Environment Analysis Tool (FEAT) was developed to help engineers and analysts more thoroughly and reliably conduct risk assessment and failure analysis. FEAT accomplishes this by providing answers to questions regarding what might have caused a particular failure; or, conversely, what effect the occurrence of a failure might have on an entire system. Additionally, FEAT can determine what common causes could have resulted in other combinations of failures. FEAT will even help determine the vulnerability of a system to failures, in light of reduced capability. FEAT also is useful in training personnel who must develop an understanding of particular systems. FEAT facilitates training on system behavior, by providing an automated environment in which to conduct 'what-if' evaluation. These types of analyses make FEAT a valuable tool for engineers and operations personnel in the design, analysis, and operation of NASA space systems.

  11. Mud pump failure analysis

    SciTech Connect

    Lewis, E.C. II

    1981-10-01

    Extrusion, the primary cause of piston failure, is the degradation of a seal caused by the seal material moving into the interface between the two parts being sealed. It is shown that operational dynamics of the mud piston lead to an aggravated extrusion condition. As both the liner wall and the piston OD lose material, the clearance gap between liner and piston increases. This gap provides the piston seal a space to move into when pressurized. This movement, called extrusion, is undesirable because the piston rubber is then subjected to abnormal stresses which it cannot tolerate. As the piston moves forward, this extruded material is gradually nibbled away. Extrusion and nibble action continue on each stroke of the pump as additional rubber moves away from the high-pressure side of the piston toward the low-pressure side. A discussion is presented of extrusion rates and seal leakage.

  12. First passage failure: Analysis alternatives

    SciTech Connect

    PAEZ,THOMAS L.; NGUYEN,H.P.; WIRSCHING,PAUL H.

    2000-04-17

    Most mechanical and structural failures can be formulated as first passage problems. The traditional approach to first passage analysis models barrier crossings as Poisson events. The crossing rate is established and used in the Poisson framework to approximate the no-crossing probability. While this approach is accurate in a number of situations, it is desirable to develop analysis alternatives for those situations where traditional analysis is less accurate and situations where it is difficult to estimate parameters of the traditional approach. This paper develops an efficient simulation approach to first passage failure analysis. It is based on simulation of segments of complex random processes with the Karhunen-Loeve expansion, use of these simulations to estimate the parameters of a Markov chain, and use of the Markov chain to estimate the probability of first passage failure. Some numerical examples are presented.

  13. Integrated Circuit Failure Analysis Hypertext Help System

    SciTech Connect

    Henderson, Christopher L.; Barton, Daniel L.; Campbell, Ann N.; Cole, Edward I; Mikawa, Russell E.; Peterson, Kenneth A.; Rife, James L.; Soden, Jerry M.

    1995-02-23

    This software assists a failure analyst performing failure analysis on integrated circuits. The software can also be used to train inexperienced failure analysts. The software also provides a method for storing information and making it easily available to experienced failure analysts.

  14. Failure analysis: Status and future trends

    SciTech Connect

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

    1995-02-01

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

  15. ATM CMG bearing failure analysis

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The cause or causes for the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2) were investigated. Skylab telemetry data were reviewed and presented in the form of parameter distributions. The theory that the problems were caused by marginal bearing lubrication was studied along with the effects of orbital conditions on lubricants. Bearing tests were performed to investigate the effect of lubricant or lack of lubricant in the ATM CMG bearings and the dispersion and migration of the lubricant. The vacuum and weightless conditions of space were simulated in the bearing tests. Analysis of the results of the tests conducted points to inadequate lubrication as the predominant factor causing the failure of ATM CMG S/N 5 (Skylab 1) and the anomalies associated with ATM CMG S/N 6 (Skylab 2).

  16. Failure Analysis and Mechanisms of Failure of Fibrous Composite Structures

    NASA Technical Reports Server (NTRS)

    Noor, A. K. (Compiler); Shuart, M. J. (Compiler); Starnes, J. H., Jr. (Compiler); Williams, J. G. (Compiler)

    1983-01-01

    The state of the art of failure analysis and current design practices, especially as applied to the use of fibrous composite materials in aircraft structures is discussed. Deficiencies in these technologies are identified, as are directions for future research.

  17. Graphical Displays Assist In Analysis Of Failures

    NASA Technical Reports Server (NTRS)

    Pack, Ginger; Wadsworth, David; Razavipour, Reza

    1995-01-01

    Failure Environment Analysis Tool (FEAT) computer program enables people to see and better understand effects of failures in system. Uses digraph models to determine what will happen to system if set of failure events occurs and to identify possible causes of selected set of failures. Digraphs or engineering schematics used. Also used in operations to help identify causes of failures after they occur. Written in C language.

  18. Manufacturing quality from electronic failure analysis results

    NASA Astrophysics Data System (ADS)

    Dobbs, B.

    The Electronic Failure Analysis Group of the AFWAL/Materials Laboratory Systems Support Division has investigated numerous electronic device failures that resulted from manufacturing process defects. The electronic failure analysis program that verifies the device failure, locates the failure site, establishes the cause of failure and recommends corrective actions is discussed in relation to improving the quality of electronic devices; performing electronic failure analysis is a high-payoff activity. Corrective actions usually involve very small costs to the manufacturer and provide the user with a large return on investment. Brief case histories are presented in regard to packaging, die attachment, solder flux removal, package moisture content, IC metallization processes, potted modules, and handling procedures affecting device cleanliness. Situations are identified where better quality control could eliminate many device defects that lead to premature part failure.

  19. Failure mode analysis to predict product reliability.

    NASA Technical Reports Server (NTRS)

    Zemanick, P. P.

    1972-01-01

    The failure mode analysis (FMA) is described as a design tool to predict and improve product reliability. The objectives of the failure mode analysis are presented as they influence component design, configuration selection, the product test program, the quality assurance plan, and engineering analysis priorities. The detailed mechanics of performing a failure mode analysis are discussed, including one suggested format. Some practical difficulties of implementation are indicated, drawn from experience with preparing FMAs on the nuclear rocket engine program.

  20. Failure Analysis at the Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Salazar, Victoria L.; Wright, Clara

    2010-01-01

    History has shown that failures occur in every engineering endeavor, and what we learn from those failures contributes to the knowledge base to safely complete future missions. The necessity of failure analysis is at its apex at the end of one aged program (i.e. Shuttle) and at the beginning of a new and untested program (i.e. Constellation). The information that we gain through failure analysis corrects the deficiencies in the current vehicle to make the next generation of vehicles more efficient and safe. The Failure Analysis and Materials Evaluation section in the Materials Science Division at the Kennedy Space Center performs metallurgical, mechanical, electrical, and non-metallic failure analysis and accident investigations on both flight hardware and ground support equipment (GSE) for the Shuttle, International Space Station, Constellation, and Launch Services Programs. This presentation will explore a variety of failure case studies at KSC and the lessons learned that can be applied in future programs.

  1. Computer aided engineering analysis of automotive bumpers

    SciTech Connect

    Glance, P.M.

    1984-01-01

    This paper presents a description of a general purpose, computer-aided engineering design methodology which has been employed in the design of automotive bumper systems. A comparison of computer-aided analysis predictions with actual test data is presented. Two case histories of bumper system designs are discussed.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  3. Failure Analysis at the Kennedy Space Center

    NASA Technical Reports Server (NTRS)

    Salazar, Victoria L.; Wright, M. Clara

    2010-01-01

    History has shown that failures occur in every engineering endeavor, and what we learn from those failures contributes to the knowledge base to safely complete future missions. The necessity of failure analysis is at its apex at the end of one aged program and at the beginning of a new and untested program. The information that we gain through failure analysis corrects the deficiencies in the current vehicle to make the next generation of vehicles more efficient and safe. The Failure Analysis and Materials Evaluation Branch in the Materials Science Division at the Kennedy Space Center performs metallurgical, mechanical, electrical, and non-metallic materials failure analyses and accident investigations on both flight hardware and ground support equipment for the Space Shuttle, International Space Station, Constellation, and Launch Services Programs. This paper will explore a variety of failure case studies at the Kennedy Space Center and the lessons learned that can be applied in future programs.

  4. Future technology challenges for failure analysis

    SciTech Connect

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

    1995-08-01

    Failure analysis is a critical element in the integrated circuit manufacturing industry. This paper explores the challenges for IC failure analysis in the environment of present and future silicon IC technology trends, using the 1994 National Technology Roadmap for Semiconductors as a technology guide. Advanced failure analysis techniques that meet the challenges of state-of-the-art IC technology are described and their applications are discussed. New paradigms will be required for failure analysis to keep pace with future advancements in IC technology.

  5. Arthritis Genetics Analysis Aids Drug Discovery

    MedlinePlus

    ... Matters NIH Research Matters January 13, 2014 Arthritis Genetics Analysis Aids Drug Discovery An international research team ... may play a role in triggering the disease. Genetic factors are also thought to play a role. ...

  6. The Failure Analysis in Traction Power System

    NASA Astrophysics Data System (ADS)

    Kim, Hyungchul; Heo, Guk-bum; Lee, Hyungwoo; Kim, Dong Jin; Kim, Jin O.

    2008-10-01

    This paper presents a failure analysis of traction power systems. The electric railway consists of traction power systems, various vehicles, operating equipment, track, overhead line and electric equipment. It is a fundamental function of traction power systems that they supply customers with acceptable reliability and high quality power. Perhaps the most commonly used reliability assessment for railway systems has been the failure analysis of the traction signal system. The reliability assessment of traction power systems has also been an indispensable issue for reliability assessment. This paper deals with the classification of railway accidents caused by electrification problems, the estimation of failure rate in power equipments and failure analysis using fault trees. In study cases, the fault tree method for failure analysis is applied to railway substations in South Korea.

  7. Light water reactor lower head failure analysis

    SciTech Connect

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

    1993-10-01

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

  8. Nurse Aide. Occupational Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    This Occupational Competency Analysis Profile (OCAP) for nurse aide (NA) is a competency list verified by expert workers that evolved from a job analysis. It identifies occupational, academic, and employability competencies needed to enter the occupation; lists and clusters them into broader units; and details the competency builders needed to…

  9. Progressive Failure Analysis of Composite Stiffened Panels

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Yarrington, Phillip W.; Collier, Craig S.; Arnold, Steven M.

    2006-01-01

    A new progressive failure analysis capability for stiffened composite panels has been developed based on the combination of the HyperSizer stiffened panel design/analysis/optimization software with the Micromechanics Analysis Code with Generalized Method of Cells (MAC/GMC). MAC/GMC discretizes a composite material s microstructure into a number of subvolumes and solves for the stress and strain state in each while providing the homogenized composite properties as well. As a result, local failure criteria may be employed to predict local subvolume failure and the effects of these local failures on the overall composite response. When combined with HyperSizer, MAC/GMC is employed to represent the ply level composite material response within the laminates that constitute a stiffened panel. The effects of local subvolume failures can then be tracked as loading on the stiffened panel progresses. Sample progressive failure results are presented at both the composite laminate and the composite stiffened panel levels. Deformation and failure model predictions are compared with experimental data from the World Wide Failure Exercise for AS4/3501-6 graphite/epoxy laminates.

  10. Failure Mode Identification Through Clustering Analysis

    NASA Technical Reports Server (NTRS)

    Arunajadai, Srikesh G.; Stone, Robert B.; Tumer, Irem Y.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Research has shown that nearly 80% of the costs and problems are created in product development and that cost and quality are essentially designed into products in the conceptual stage. Currently, failure identification procedures (such as FMEA (Failure Modes and Effects Analysis), FMECA (Failure Modes, Effects and Criticality Analysis) and FTA (Fault Tree Analysis)) and design of experiments are being used for quality control and for the detection of potential failure modes during the detail design stage or post-product launch. Though all of these methods have their own advantages, they do not give information as to what are the predominant failures that a designer should focus on while designing a product. This work uses a functional approach to identify failure modes, which hypothesizes that similarities exist between different failure modes based on the functionality of the product/component. In this paper, a statistical clustering procedure is proposed to retrieve information on the set of predominant failures that a function experiences. The various stages of the methodology are illustrated using a hypothetical design example.

  11. The National Strategic Plan of South Africa: what are the prospects of success after the repeated failure of previous AIDS policy?

    PubMed

    Wouters, Edwin; van Rensburg, H C J; Meulemans, H

    2010-05-01

    Hitherto, the story of HIV/AIDS in South Africa is, to a large extent, one of lost opportunities. Whereas the country has one of the worst epidemics in the world, consecutive national AIDS strategies have been repeatedly marked by failure over almost three decades. Understandably, South Africa's most recent HIV/AIDS policy, the HIV & AIDS and STI Strategic Plan for South Africa, 2007-2011 (NSP), has been greeted with general acclaim. However, what are its real prospects of success against the backdrop of the repeated failures of the past? The first objective of this review is to systematically identify the core reasons for past policy failures. Using a comprehensive analytical framework, this article presents a systematic review of the literature on postapartheid AIDS policy in South Africa. The analysis demonstrates that a complex interplay among the content, context, actors and process of AIDS policy created a gap between policy making and policy implementation, which rendered near-ideal AIDS policies ineffective. Secondly, we evaluate the chances of success of the current NSP by examining both the policy-making phase and the resulting policy document in light of the reasons for past policy failures. Our analysis shows that the NSP contains dynamic and comprehensive policy content, sensitive to the socio-economic and cultural dimensions of HIV/AIDS. However, many of the political actors that hampered treatment implementation in the past, and who deepened the gap between government and civil society, are still in office. Monetary and human resource shortages also create a policy context that is infertile for the implementation of a comprehensive HIV/AIDS strategy, as envisaged in the NSP. Finally, these health system restrictions have a clear negative impact on the process of policy implementation. Without the mobilization of people living with HIV/AIDS and their communities, the NSP will be ineffective in bridging the gap between policy intentions and policy

  12. Failure analysis of high performance ballistic fibers

    NASA Astrophysics Data System (ADS)

    Spatola, Jennifer S.

    High performance fibers have a high tensile strength and modulus, good wear resistance, and a low density, making them ideal for applications in ballistic impact resistance, such as body armor. However, the observed ballistic performance of these fibers is much lower than the predicted values. Since the predictions assume only tensile stress failure, it is safe to assume that the stress state is affecting fiber performance. The purpose of this research was to determine if there are failure mode changes in the fiber fracture when transversely loaded by indenters of different shapes. An experimental design mimicking transverse impact was used to determine any such effects. Three different indenters were used: round, FSP, and razor blade. The indenter height was changed to change the angle of failure tested. Five high performance fibers were examined: KevlarRTM KM2, SpectraRTM 130d, DyneemaRTM SK-62 and SK-76, and ZylonRTM 555. Failed fibers were analyzed using an SEM to determine failure mechanisms. The results show that the round and razor blade indenters produced a constant failure strain, as well as failure mechanisms independent of testing angle. The FSP indenter produced a decrease in failure strain as the angle increased. Fibrillation was the dominant failure mechanism at all angles for the round indenter, while through thickness shearing was the failure mechanism for the razor blade. The FSP indenter showed a transition from fibrillation at low angles to through thickness shearing at high angles, indicating that the round and razor blade indenters are extreme cases of the FSP indenter. The failure mechanisms observed with the FSP indenter at various angles correlated with the experimental strain data obtained during fiber testing. This indicates that geometry of the indenter tip in compression is a contributing factor in lowering the failure strain of the high performance fibers. TEM analysis of the fiber failure mechanisms was also attempted, though without

  13. Computer aided nonlinear electrical networks analysis

    NASA Technical Reports Server (NTRS)

    Slapnicar, P.

    1977-01-01

    Techniques used in simulating an electrical circuit with nonlinear elements for use in computer-aided circuit analysis programs are described. Elements of the circuit include capacitors, resistors, inductors, transistors, diodes, and voltage and current sources (constant or time varying). Simulation features are discussed for dc, ac, and/or transient circuit analysis. Calculations are based on the model approach of formulating the circuit equations. A particular solution of transient analysis for nonlinear storage elements is described.

  14. Failure analysis of surface-micromachined microengines

    SciTech Connect

    Peterson, K.A.; Tangyunyong, P.; Pimentel, A.A.

    1998-11-01

    Microelectronic failure analysis (FA) has been an integral part of the development of state-of-the-art integrated circuits. FA of MicroElectroMechanical Systems (MEMS) is moving from its infancy stage to assume an important role in the successful design, fabrication, performance and reliability analysis for this new technology. In previous work, the authors focused on the application of several techniques developed for integrated circuit analysis to an earlier version of a surface micromachined microengine fabricated at Sandia. Recently, they have identified important new failure modes in binary counters that incorporate a newer design of the microengine, using a subset of integrated circuit failure analysis techniques including optical microscopy, focused ion beam (FIB) techniques, atomic force microscopy (AFM), and scanning electron microscopy (SEM). The primary failure mode they have identified is directly related to visible wear on bearing surfaces. In this paper, they describe in detail the characteristics of the failure modes in binary counters. They also compare the failure characteristics with those of an earlier version of the microengine.

  15. Plastic and Failure Analysis of Composites

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.; Johnson, W. S.

    1985-01-01

    Three-dimensional finite-element computer program called PAFAC (Plastic and Failure Analysis of Composites) developed for elastic/plastic analysis of fiber-reinforced composite materials and structures. PAFAC written in FORTRAN IV for batch execution. Particularly suited for analyzing laminated metal-matrix composites.

  16. Application of a neural network as a potential aid in predicting NTF pump failure

    NASA Technical Reports Server (NTRS)

    Rogers, James L.; Hill, Jeffrey S.; Lamarsh, William J., II; Bradley, David E.

    1993-01-01

    The National Transonic Facility has three centrifugal multi-stage pumps to supply liquid nitrogen to the wind tunnel. Pump reliability is critical to facility operation and test capability. A highly desirable goal is to be able to detect a pump rotating component problem as early as possible during normal operation and avoid serious damage to other pump components. If a problem is detected before serious damage occurs, the repair cost and downtime could be reduced significantly. A neural network-based tool was developed for monitoring pump performance and aiding in predicting pump failure. Once trained, neural networks can rapidly process many combinations of input values other than those used for training to approximate previously unknown output values. This neural network was applied to establish relationships among the critical frequencies and aid in predicting failures. Training pairs were developed from frequency scans from typical tunnel operations. After training, various combinations of critical pump frequencies were propagated through the neural network. The approximated output was used to create a contour plot depicting the relationships of the input frequencies to the output pump frequency.

  17. Automatic tools for microprocessor failure analysis

    NASA Astrophysics Data System (ADS)

    Conard, Didier; Laurent, J.; Velazco, Raoul; Ziade, Haissam; Cabestany, J.; Sala, F.

    A new approach for fault location when testing microprocessors is presented. The startpoint for the backtracing analysis converging to the failure is constituted by the automatic localization of a reduced area. Automatic image comparison based on pattern recognition is performed by means of an electron beam tester. The developed hardware and software tools allow large circuit areas to be covered offering powerful diagnosis capabilities to the user. The validation of this technique was performed on faulty 68000 microprocessors. It shows the feasibility of the automation of the first and most important step of failure analysis: fault location at the chip surface.

  18. Failure Analysis of Ceramic Components

    SciTech Connect

    B.W. Morris

    2000-06-29

    Ceramics are being considered for a wide range of structural applications due to their low density and their ability to retain strength at high temperatures. The inherent brittleness of monolithic ceramics requires a departure from the deterministic design philosophy utilized to analyze metallic structural components. The design program ''Ceramic Analysis and Reliability Evaluation of Structures Life'' (CARES/LIFE) developed by NASA Lewis Research Center uses a probabilistic approach to predict the reliability of monolithic components under operational loading. The objective of this study was to develop an understanding of the theories used by CARES/LIFE to predict the reliability of ceramic components and to assess the ability of CARES/LIFE to accurately predict the fast fracture behavior of monolithic ceramic components. A finite element analysis was performed to determine the temperature and stress distribution of a silicon carbide O-ring under diametral compression. The results of the finite element analysis were supplied as input into CARES/LIFE to determine the fast fracture reliability of the O-ring. Statistical material strength parameters were calculated from four-point flexure bar test data. The predicted reliability showed excellent correlation with O-ring compression test data indicating that the CARES/LIFE program can be used to predict the reliability of ceramic components subjected to complicated stress states using material properties determined from simple uniaxial tensile tests.

  19. A streamlined failure mode and effects analysis

    SciTech Connect

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

    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.

  20. Interfacing Computer Aided Parallelization and Performance Analysis

    NASA Technical Reports Server (NTRS)

    Jost, Gabriele; Jin, Haoqiang; Labarta, Jesus; Gimenez, Judit; Biegel, Bryan A. (Technical Monitor)

    2003-01-01

    When porting sequential applications to parallel computer architectures, the program developer will typically go through several cycles of source code optimization and performance analysis. We have started a project to develop an environment where the user can jointly navigate through program structure and performance data information in order to make efficient optimization decisions. In a prototype implementation we have interfaced the CAPO computer aided parallelization tool with the Paraver performance analysis tool. We describe both tools and their interface and give an example for how the interface helps within the program development cycle of a benchmark code.

  1. FAILURE ANALYSIS: WASTEWATER DRUM BULGING

    SciTech Connect

    Vormelker, P

    2008-09-15

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

  2. Failure analysis of fuze power supply

    SciTech Connect

    Menke, J.T.

    1996-10-01

    Batteries in storage which were used in electronic fuzes were found to be leaking after 5 years. The leaking battery ampules were made of copper and contained mixture of fluoboric acid and methylene bromide. The corrosion mechanism is described along with the testing/analysis required to simulate the field failures.

  3. Failure Analysis of Composite Structure Materials.

    DTIC Science & Technology

    1986-05-01

    listed in order of preference, based on applicability, reliability, cost , and sample requirements. Figure 5-4. Failure Analysis Technique...development of a methodology in which optical analysis is used to increase the time and cost effectiveness of analyzing failed composite material struc...regarding the integrity of the bond. Accurate bondline defect information was achieved in such structures utilizing a transportable californium -252 (2 5 2

  4. Analysis of cascading failure in gene networks.

    PubMed

    Sun, Longxiao; Wang, Shudong; Li, Kaikai; Meng, Dazhi

    2012-01-01

    It is an important subject to research the functional mechanism of cancer-related genes make in formation and development of cancers. The modern methodology of data analysis plays a very important role for deducing the relationship between cancers and cancer-related genes and analyzing functional mechanism of genome. In this research, we construct mutual information networks using gene expression profiles of glioblast and renal in normal condition and cancer conditions. We investigate the relationship between structure and robustness in gene networks of the two tissues using a cascading failure model based on betweenness centrality. Define some important parameters such as the percentage of failure nodes of the network, the average size-ratio of cascading failure, and the cumulative probability of size-ratio of cascading failure to measure the robustness of the networks. By comparing control group and experiment groups, we find that the networks of experiment groups are more robust than that of control group. The gene that can cause large scale failure is called structural key gene. Some of them have been confirmed to be closely related to the formation and development of glioma and renal cancer respectively. Most of them are predicted to play important roles during the formation of glioma and renal cancer, maybe the oncogenes, suppressor genes, and other cancer candidate genes in the glioma and renal cancer cells. However, these studies provide little information about the detailed roles of identified cancer genes.

  5. Training Aids for Online Instruction: An Analysis.

    ERIC Educational Resources Information Center

    Guy, Robin Frederick

    This paper describes a number of different types of training aids currently employed in online training: non-interactive audiovisual presentations; interactive computer-based aids; partially interactive aids based on recorded searches; print-based materials; and kits. The advantages and disadvantages of each type of aid are noted, and a table…

  6. Progressive Failure Analysis Methodology for Laminated Composite Structures

    NASA Technical Reports Server (NTRS)

    Sleight, David W.

    1999-01-01

    A progressive failure analysis method has been developed for predicting the failure of laminated composite structures under geometrically nonlinear deformations. The progressive failure analysis uses C(exp 1) shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms and several options are available to degrade the material properties after failures. The progressive failure analysis method is implemented in the COMET finite element analysis code and can predict the damage and response of laminated composite structures from initial loading to final failure. The different failure criteria and material degradation methods are compared and assessed by performing analyses of several laminated composite structures. Results from the progressive failure method indicate good correlation with the existing test data except in structural applications where interlaminar stresses are important which may cause failure mechanisms such as debonding or delaminations.

  7. SAS: a yield/failure analysis software tool

    NASA Astrophysics Data System (ADS)

    de Jong Perez, Susana

    1996-09-01

    As the device sizes decrease and the number of interconnect levels and wafer size increase, the device yield and failure analysis becomes more complex. Currently, software tools are being used to perform visual inspection techniques after many operations during which defects are detected on a sample of wafers. However, it has been observed that the correlation between the yield predicted on the basis of the defects found during such observations and the yield determined electrically at wafer final test is low. Of a greater interest to yield/failure analysis software tools is statistical analysis software. SASTM can perform extensive data analysis on kerf test structures' electrical parameters. In addition, the software can merge parametric and yield/fail bins data which reduces the data collection and data reduction activities involved in the correlation of device parameters to circuit functional operation. The data is saved in large databases which allow storage and later retrieval of historical data in order to evaluate process shifts and changes and their effect on yield. The merge of process parameters and on-line measurements with final electrical data, is also possible with the aid of process parameter extraction software. All of this data analysis provides excellent feedback about integrated circuit wafer processing.

  8. Factors Influencing Progressive Failure Analysis Predictions for Laminated Composite Structure

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.

    2008-01-01

    Progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model for use with a nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details are described in the present paper. Parametric studies for laminated composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented and to demonstrate their influence on progressive failure analysis predictions.

  9. Federal Aid to Education: A Student Level Analysis.

    ERIC Educational Resources Information Center

    Verstegen, Deborah A.; Torrence, Patricia T.

    A study that examined the magnitude of federal aid to individual students and the targeting of those funds based on need found that although federal aid to education averages 7 percent nationwide, little work has been done that disaggregates these amounts by locality. The study included an intradistrict analysis of federal-education aid per pupil.…

  10. Failure Analysis of Worn Surface Micromachined Microengines

    SciTech Connect

    Walraven, Jeremy A.; Headley, Thomas J.; Campbell, Ann N.; Tanner, Danelle M.

    1999-07-21

    Failure analysis (FA) tools have been applied to analyze failing polysilicon microengines. These devices were stressed to failure under accelerated conditions in both oxidizing and non-oxidizing environments. The dominant failure mechanism of these microengines was identified as wear of rubbing surfaces. This often results in either seized microengines or microengines with broken pin joints. Analysis of these failed polysilicon devices found that wear debris was produced in both oxidizing and non-oxidizing environments. By varying the relative percent humidity (%RH), they observed an increase in the amount of wear debris with decreasing humidity. Plan view imaging using scanning electron microscopy revealed build-up of wear debris on the surface of microengines. Focused ion beam (FIB) cross sections revealed the location and build-up of wear debris on the surface of microengines. Focused ion beam (FIB) cross sections revealed the location and build-up of wear debris within the microengine. Seized regions were also observed in the pin joint area using FIB processing. By using transmission electron microscopy in conjunction with energy dispersive x-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS), they were able to identify wear debris produced in low (1.8% RH), medium and high (39% RH) humidities.

  11. FASTHELP. Integrated Circuit Failure Analysis Hypertext Help System

    SciTech Connect

    Henderson, C; Barton, D; Campbell, A; Cole, E; Mikawa, R E; Peterson, K A; Rife, J L; Soden, J M

    1994-09-30

    This software assists a failure analyst performing failure analysis on integrated circuits. The software can also be used to train inexperienced failure analysts. The software also provides a method for storing information and making it easily available to experienced failure analysts.

  12. Water Ingress Failure Analysis of Whistler II Unit

    DTIC Science & Technology

    2014-08-01

    Water Ingress Failure Analysis of Whistler II Unit by Andrew J Bayba ARL-TN-0623 August 2014...Failure Analysis of Whistler II Unit Andrew J Bayba Sensors and Electron Devices Directorate, ARL...Ingress Failure Analysis of Whistler II Unit 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Andrew J Bayba

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

    PubMed Central

    2012-01-01

    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 between the teams’ estimates

  14. AIDS

    MedlinePlus

    ... page: //medlineplus.gov/ency/article/000594.htm HIV/AIDS To use the sharing features on this page, ... immunodeficiency virus (HIV) is the virus that causes AIDS. When a person becomes infected with HIV, the ...

  15. Timing analysis of PWR fuel pin failures

    SciTech Connect

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

    1992-09-01

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

  16. Failure Analysis of Sapphire Refractive Secondary Concentrators

    NASA Technical Reports Server (NTRS)

    Salem, Jonathan A.; Quinn, George D.

    2009-01-01

    Failure analysis was performed on two sapphire, refractive secondary concentrators (RSC) that failed during elevated temperature testing. Both concentrators failed from machining/handling damage on the lens face. The first concentrator, which failed during testing to 1300 C, exhibited a large r-plane twin extending from the lens through much of the cone. The second concentrator, which was an attempt to reduce temperature gradients and failed during testing to 649 C, exhibited a few small twins on the lens face. The twins were not located at the origin, but represent another mode of failure that needs to be considered in the design of sapphire components. In order to estimate the fracture stress from fractographic evidence, branching constants were measured on sapphire strength specimens. The fractographic analysis indicated radial tensile stresses of 44 to 65 MPa on the lens faces near the origins. Finite element analysis indicated similar stresses for the first RSC, but lower stresses for the second RSC. Better machining and handling might have prevented the fractures, however, temperature gradients and resultant thermal stresses need to be reduced to prevent twinning.

  17. Cycles till failure of silver-zinc cells with competing failure modes - Preliminary data analysis

    NASA Technical Reports Server (NTRS)

    Sidik, S. M.; Leibecki, H. F.; Bozek, J. M.

    1980-01-01

    The data analysis of cycles to failure of silver-zinc electrochemical cells with competing failure modes is presented. The test ran 129 cells through charge-discharge cycles until failure; preliminary data analysis consisted of response surface estimate of life. Batteries fail through low voltage condition and an internal shorting condition; a competing failure modes analysis was made using maximum likelihood estimation for the extreme value life distribution. Extensive residual plotting and probability plotting were used to verify data quality and selection of model.

  18. PAFAC- PLASTIC AND FAILURE ANALYSIS OF COMPOSITES

    NASA Technical Reports Server (NTRS)

    Bigelow, C. A.

    1994-01-01

    The increasing number of applications of fiber-reinforced composites in industry demands a detailed understanding of their material properties and behavior. A three-dimensional finite-element computer program called PAFAC (Plastic and Failure Analysis of Composites) has been developed for the elastic-plastic analysis of fiber-reinforced composite materials and structures. The evaluation of stresses and deformations at edges, cut-outs, and joints is essential in understanding the strength and failure for metal-matrix composites since the onset of plastic yielding starts very early in the loading process as compared to the composite's ultimate strength. Such comprehensive analysis can only be achieved by a finite-element program like PAFAC. PAFAC is particularly suited for the analysis of laminated metal-matrix composites. It can model the elastic-plastic behavior of the matrix phase while the fibers remain elastic. Since the PAFAC program uses a three-dimensional element, the program can also model the individual layers of the laminate to account for thickness effects. In PAFAC, the composite is modeled as a continuum reinforced by cylindrical fibers of vanishingly small diameter which occupy a finite volume fraction of the composite. In this way, the essential axial constraint of the phases is retained. Furthermore, the local stress and strain fields are uniform. The PAFAC finite-element solution is obtained using the displacement method. Solution of the nonlinear equilibrium equations is obtained with a Newton-Raphson iteration technique. The elastic-plastic behavior of composites consisting of aligned, continuous elastic filaments and an elastic-plastic matrix is described in terms of the constituent properties, their volume fractions, and mutual constraints between phases indicated by the geometry of the microstructure. The program uses an iterative procedure to determine the overall response of the laminate, then from the overall response determines the stress

  19. Computer Aided Modeling and Post Processing with NASTRAN Analysis

    NASA Technical Reports Server (NTRS)

    Boroughs, R. R.

    1984-01-01

    Computer aided engineering systems are invaluable tools in performing NASTRAN finite element analysis. These techniques are implemented in both the pre-processing and post-processing phases of the NASTRAN analysis. The finite element model development, or pre-processing phase, was automated with a computer aided modeling program called Supertabl, and the review and interpretation of the results of the NASTRAN analysis, or post-processing phase, was automated with a computer aided plotting program called Output Display. An intermediate program, Nasplot, which was developed in-house, has also helped to cut down on the model checkout time and reduce errors in the model. An interface has been established between the finite element computer aided engineering system and the Learjet computer aided design system whereby data can be transferred back and forth between the two. These systems have significantly improved productivity and the ability to perform NASTRAN analysis in response to product development requests.

  20. Is Health Aid Reaching the Poor? Analysis of Household Data from Aid Recipient Countries

    PubMed Central

    Bendavid, Eran

    2014-01-01

    Objective To determine the extent to which the narrowing of child mortality across wealth gradients has been related to foreign aid to the health sector in low- and middle-income countries. Methods Mortality and wealth data on 989,901 under-5 children from 957,674 households in 49 aid recipient countries in Africa, Asia, South America, and the Caribbean between 1993 and 2012 were used in the analysis. Declines in under-5 mortality in the four poorest wealth quantiles were compared to the decline among the wealthiest at varying levels of health aid per capita using fixed effects multivariable regression models and controlling for maternal education, urbanization, and domestic spending on health among recipient countries. Results Each additional dollar in total health aid per capita was associated with 5.7 fewer deaths per 10,000 child-years among children in the poorest relative to the wealthiest households (p<0.001). This was also true when measured in percent declines (1.90% faster decline in under-5 mortality among the poorest compared with the wealthiest with each dollar in total health aid, p = 0.008). The association was stronger when using health aid specifically for malaria than total health aid, 12.60% faster decline among the poorest compared with the wealthiest with each dollar in malaria aid, p = 0.001. Conclusions Foreign aid to the health sector is preferentially related to reductions in under-5 mortality among the poorest compared with the wealthiest. Health aid addressing malaria, which imposes a disproportionate burden among the poor, may explain the observed effect. PMID:24404148

  1. Control methods for aiding a pilot during STOL engine failure transients

    NASA Technical Reports Server (NTRS)

    Nelson, E. R.; Debra, D. B.

    1976-01-01

    Candidate autopilot control laws that control the engine failure transient sink rates by demonstrating the engineering application of modern state variable control theory were defined. The results of approximate modal analysis were compared to those derived from full state analyses provided from computer design solutions. The aircraft was described, and a state variable model of its longitudinal dynamic motion due to engine and control variations was defined. The classical fast and slow modes were assumed to be sufficiently different to define reduced order approximations of the aircraft motion amendable to hand analysis control definition methods. The original state equations of motion were also applied to a large scale state variable control design program, in particular OPTSYS. The resulting control laws were compared with respect to their relative responses, ease of application, and meeting the desired performance objectives.

  2. X-Ray Computed Tomography for Failure Analysis Investigations

    DTIC Science & Technology

    1993-05-01

    AD-A268 086 WL-TR-93-4047 X - RAY COMPUTED TOMOGRAPHY FOR FAILURE ANALYSIS INVESTIGATIONS Richard H. Bossi William Shepherd Boeing Defense & Space... X - Ray Computed Tomography for Failure Analysis Investigations PE: 63112F PR: 3153 6. AUTilOR(S) TA: 00 Richard H. Bossi and William Shepherd WU: 06 7...feature detection and three-dimensional positioning capability of X - ray computed tomography are valuable and cost saving assets to a failure analysis

  3. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 4 2010-01-01 2010-01-01 false Probability of failure analysis. 417.224..., DEPARTMENT OF TRANSPORTATION LICENSING LAUNCH SAFETY Flight Safety Analysis § 417.224 Probability of failure analysis. (a) General. All flight safety analyses for a launch, regardless of hazard or phase of...

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Nurse Aide. Ohio's Competency Analysis Profile.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Vocational Instructional Materials Lab.

    Developed through a modified DACUM (Developing a Curriculum) process involving business, industry, labor, and community agency representatives in Ohio, this document is a comprehensive and verified employer competency profile for nurses' aides. The list contains units (with and without subunits), competencies, and competency builders that identify…

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

    NASA Technical Reports Server (NTRS)

    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.

  7. Reliability Analysis of Systems Subject to First-Passage Failure

    NASA Technical Reports Server (NTRS)

    Lutes, Loren D.; Sarkani, Shahram

    2009-01-01

    An obvious goal of reliability analysis is the avoidance of system failure. However, it is generally recognized that it is often not feasible to design a practical or useful system for which failure is impossible. Thus it is necessary to use techniques that estimate the likelihood of failure based on modeling the uncertainty about such items as the demands on and capacities of various elements in the system. This usually involves the use of probability theory, and a design is considered acceptable if it has a sufficiently small probability of failure. This report contains findings of analyses of systems subject to first-passage failure.

  8. Applying Systems Analysis to Program Failure in Organizations.

    ERIC Educational Resources Information Center

    Holt, Margaret E.; And Others

    1986-01-01

    Certain systems analysis techniques can be applied to examinations of program failure in continuing education to locate weaknesses in planning and implementing stages. Questions to guide an analysis and various procedures are recommended. Twelve issues that contribute to failures or discontinuations are identified. (Author/MLW)

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  10. Failure Analysis of a Pilot Scale Melter

    SciTech Connect

    Imrich, K J

    2001-09-14

    Failure of the pilot-scale test melter resulted from severe overheating of the Inconel 690 jacketed molybdenum electrode. Extreme temperatures were required to melt the glass during this campaign because the feed material contained a very high waste loading.

  11. Reliability Estimation and Failure Analysis of Multilayer Ceramic Chip Capacitors

    NASA Astrophysics Data System (ADS)

    Yang, Seok Jun; Kim, Jin Woo; Ryu, Dong Su; Kim, Myung Soo; Jang, Joong Soon

    This paper presents the failure analysis and the reliability estimation of a multilayer ceramic chip capacitor. For the failed samples used in an automobile engine control unit, failure analysis was made to identify the root cause of failure and it was shown that the migration and the avalanche breakdown were the dominant failure mechanisms. Next, an accelerated life testing was designed to estimate the life of the MLCC. It is assumed that Weibull lifetime distribution and the life-stress relationship proposed Prokopowicz and Vaskas. The life-stress relationship and the acceleration factor are estimated by analyzing the accelerated life test data.

  12. Analysis of the causes of pump failure and differences of failure characteristics.

    PubMed

    Korving, H; Ottenhoff, E C; Korving, H

    2008-01-01

    It is generally accepted that sewage pumping stations are directly responsible for affecting sewer system performance in terms of combined sewer overflows and flooding. However, the specific causes of pump failure are unknown. This paper presents the analysis of pump failure data provided by four sewer management authorities in The Netherlands. Pump failures have been studied accounting for the nature of failures, operation and maintenance procedures of the management authority, ageing of the pumps and changes in the environment of pumps. Pumps have been clustered on the basis of specific characteristics of their 'environment', including pump age, operating time, pump capacity and degree of pollution of the sewage. The analysis shows that the well known 'bathtub' type failure rate curve can describe failures of sewage pumps. The impact of the degree of pollution of the sewage, however, is less clear. Operating time and total pumping capacity show no correlation with failure rate. Consequently, further research using data mining techniques is needed to separate the impact of the different aspects of the environment of a pump.

  13. Failure analysis of explanted sternal wires.

    PubMed

    Shih, Chun-Ming; Su, Yea-Yang; Lin, Shing-Jong; Shih, Chun-Che

    2005-05-01

    To classify and understand the mechanisms of surface damages and fracture mechanisms of sternal wires, explanted stainless steel sternal wires were collected from patients with sternal dehiscence following open-heart surgery. Surface alterations and fractured ends of sternal wires were examined and analyzed. Eighty fractured wires extracted from 25 patients from January 1999 to December 2003, with mean implantation interval of 55+/-149 days (range 5-729 days) after cardiac surgery, were studied by various techniques. The extracted wires were cleaned and the fibrotic tissues were removed. Irregularities and fractured ends were assayed by a scanning electron microscopy. After stereomicroscopy and documentation, the explants were cleaned with 1% sodium hypochlorite to remove the blood and tissues and was followed by cleaned with deionized water and alcohol. The explants were examined by stereomicroscopy, and irregularities on surface and fracture surfaces of sternal wires were assayed by scanning electron microscopy, energy dispersive X-ray analysis (EDAX) and X-ray mapping. The explants with surrounding fibrotic tissue were stained and examined with stereomicroscopy and transmission electronic microscopy. Corrosion pits were found on the surface of explanted sternal wires. EDAX and X-ray mapping examinations revealed diminution of nickel concentration in the severely corroded pits on sternal wires. A feature of transgranular cracking was observed for stress corrosion cracking and striation character for typical corrosion fatigue was also identified. TEM examination of tissue showed the metallic particles in phagolysosomes of macrophages inside the surrounding sternal tissue. The synergic effect of hostile environment and the stress could be the precursors of failures for sternal wires.

  14. User-Defined Material Model for Progressive Failure Analysis

    NASA Technical Reports Server (NTRS)

    Knight, Norman F. Jr.; Reeder, James R. (Technical Monitor)

    2006-01-01

    An overview of different types of composite material system architectures and a brief review of progressive failure material modeling methods used for structural analysis including failure initiation and material degradation are presented. Different failure initiation criteria and material degradation models are described that define progressive failure formulations. These progressive failure formulations are implemented in a user-defined material model (or UMAT) for use with the ABAQUS/Standard1 nonlinear finite element analysis tool. The failure initiation criteria include the maximum stress criteria, maximum strain criteria, the Tsai-Wu failure polynomial, and the Hashin criteria. The material degradation model is based on the ply-discounting approach where the local material constitutive coefficients are degraded. Applications and extensions of the progressive failure analysis material model address two-dimensional plate and shell finite elements and three-dimensional solid finite elements. Implementation details and use of the UMAT subroutine are described in the present paper. Parametric studies for composite structures are discussed to illustrate the features of the progressive failure modeling methods that have been implemented.

  15. X-framework: Space system failure analysis framework

    NASA Astrophysics Data System (ADS)

    Newman, John Steven

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

  16. Common-Cause Failure Analysis in Event Assessment

    SciTech Connect

    Dana L. Kelly; Dale M. Rasmuson

    2008-09-01

    This paper describes the approach taken by the U. S. Nuclear Regulatory Commission to the treatment of common-cause failure in probabilistic risk assessment of operational events. The approach is based upon the Basic Parameter Model for common-cause failure, and examples are illustrated using the alpha-factor parameterization, the approach adopted by the NRC in their Standardized Plant Analysis Risk (SPAR) models. The cases of a failed component (with and without shared common-cause failure potential) and a component being unavailable due to preventive maintenance or testing are addressed. The treatment of two related failure modes (e.g., failure to start and failure to run) is a new feature of this paper. These methods are being applied by the NRC in assessing the risk significance of operational events for the Significance Determination Process (SDP) and the Accident Sequence Precursor (ASP) program.

  17. Failure Analysis of Electrical Pin Connectors

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Baughman, James M.; Smith, Stephen W.; Herath, Jeffrey A.

    2008-01-01

    A study was initiated to determine the root cause of failure for circuit board electrical connection pins that failed during vibRatory testing. The circuit board is part of an unmanned space probe, and the vibratory testing was performed to ensure component survival of launch loading conditions. The results of this study show that the pins failed as a result of fatigue loading.

  18. AIDS Education for Tanzanian Youth: A Mediation Analysis

    ERIC Educational Resources Information Center

    Stigler, Melissa H.; Kugler, K. C.; Komro, K. A.; Leshabari, M. T.; Klepp, K. I.

    2006-01-01

    Mediation analysis is a statistical technique that can be used to identify mechanisms by which intervention programs achieve their effects. This paper presents the results of a mediation analysis of Ngao, an acquired immunodeficiency syndrome (AIDS) education program that was implemented with school children in Grades 6 and 7 in Tanzania in the…

  19. Computer-Aided Communication Satellite System Analysis and Optimization.

    ERIC Educational Resources Information Center

    Stagl, Thomas W.; And Others

    Various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. The rationale for selecting General Dynamics/Convair's Satellite Telecommunication Analysis and Modeling Program (STAMP) in modified form to aid in the system costing and sensitivity analysis work in the Program on…

  20. Computer Aided Data Analysis in Sociometry

    ERIC Educational Resources Information Center

    Langeheine, Rolf

    1978-01-01

    A computer program which analyzes sociometric data is presented. The SDAS program provides classical sociometric analysis. Multi-dimensional scaling and cluster analysis techniques may be combined with the MSP program. (JKS)

  1. Cycles till failure of silver-zinc cells with completing failures modes: Preliminary data analysis

    NASA Technical Reports Server (NTRS)

    Sidik, S. M.; Leibecki, H. F.; Bozek, J. M.

    1980-01-01

    One hundred and twenty nine cells were run through charge-discharge cycles until failure. The experiment design was a variant of a central composite factorial in five factors. Preliminary data analysis consisted of response surface estimation of life. Batteries fail under two basic modes; a low voltage condition and an internal shorting condition. A competing failure modes analysis using maximum likelihood estimation for the extreme value life distribution was performed. Extensive diagnostics such as residual plotting and probability plotting were employed to verify data quality and choice of model.

  2. OH-58 helicopter transmission failure analysis

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  3. Risk analysis. HIV / AIDS country profile: Nigeria.

    PubMed

    1997-02-01

    The World Health Organization estimated that 2.2% of Nigeria's adult population was infected with HIV by the end of 1995. A 1993-94 sentinel surveillance report found a 3.8% HIV seroprevalence level among sexually active Nigerians sampled. HIV prevalence is rising in the country. Incidence and prevalence data are presented on HIV and AIDS in sections on antenatal clinics, HIV-1 and HIV-2, group variations, regional variations, age variations, prostitutes, and infection by blood. The Nigerian government has projected that there could be 7 million people infected with HIV in the country by the year 2000. Background is presented on the economy, living standards, health, and population. Vulnerability is then considered with regard to population mobility, drug trafficking, the vulnerability of women, the international sex trade, the military presence in Liberia, sexual attitudes, poverty, and ignorance. The responses of the government and the domestic nongovernment sector are then presented followed by description of external assistance from the World Bank, the US Agency for International Development, the British Overseas Development Agency, the World Health Organization, the private sector, and the European Commission.

  4. Safety Core Insulator Failures Reliability Analysis

    DTIC Science & Technology

    2006-10-01

    given below: 1. Improper installation a. Installed upside down. Air bubble exposes belt in high field area ( Haiku ) b. Installed with inadequate...ground. Cause – improperly installed spelter socket. New Safety Core Haiku , HI 1 EM-1 Down lead dogleg counterweight insulator exploded. Cause...insulators failed when they hit the ground following the failure of an improperly installed spelter socket. 4. Haiku , HI. Valley span antenna (Dec 1996

  5. Collective consciousness and its pathologies: understanding the failure of AIDS control and treatment in the United States.

    PubMed

    Wallace, Rodrick M; Fullilove, Mindy T; Fullilove, Robert E; Wallace, Deborah N

    2007-02-26

    We address themes of distributed cognition by extending recent formal developments in the theory of individual consciousness. While single minds appear biologically limited to one dynamic structure of linked cognitive submodules instantiating consciousness, organizations, by contrast, can support several, sometimes many, such constructs simultaneously, although these usually operate relatively slowly. System behavior remains, however, constrained not only by culture, but by a developmental path dependence generated by organizational history, in the context of market selection pressures. Such highly parallel multitasking--essentially an institutional collective consciousness--while capable of reducing inattentional blindness and the consequences of failures within individual workspaces, does not eliminate them, and introduces new characteristic malfunctions involving the distortion of information sent between workspaces and the possibility of pathological resilience--dysfunctional institutional lock-in. Consequently, organizations remain subject to canonical and idiosyncratic failures analogous to, but more complicated than, those afflicting individuals. Remediation is made difficult by the manner in which pathological externalities can write images of themselves onto both institutional function and corrective intervention. The perspective is applied to the failure of AIDS control and treatment in the United States.

  6. Collective consciousness and its pathologies: Understanding the failure of AIDS control and treatment in the United States

    PubMed Central

    Wallace, Rodrick M; Fullilove, Mindy T; Fullilove, Robert E; Wallace, Deborah N

    2007-01-01

    We address themes of distributed cognition by extending recent formal developments in the theory of individual consciousness. While single minds appear biologically limited to one dynamic structure of linked cognitive submodules instantiating consciousness, organizations, by contrast, can support several, sometimes many, such constructs simultaneously, although these usually operate relatively slowly. System behavior remains, however, constrained not only by culture, but by a developmental path dependence generated by organizational history, in the context of market selection pressures. Such highly parallel multitasking – essentially an institutional collective consciousness – while capable of reducing inattentional blindness and the consequences of failures within individual workspaces, does not eliminate them, and introduces new characteristic malfunctions involving the distortion of information sent between workspaces and the possibility of pathological resilience – dysfunctional institutional lock-in. Consequently, organizations remain subject to canonical and idiosyncratic failures analogous to, but more complicated than, those afflicting individuals. Remediation is made difficult by the manner in which pathological externalities can write images of themselves onto both institutional function and corrective intervention. The perspective is applied to the failure of AIDS control and treatment in the United States. PMID:17324268

  7. Failure Modes and Effects Analysis (FMEA): A Bibliography

    NASA Technical Reports Server (NTRS)

    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.

  8. Theoretical analysis of electromigration-induced failure of metallic thin films due to transgranular void propagation

    SciTech Connect

    Gungor, M.R.; Maroudas, D.

    1999-02-01

    Failure of metallic thin films driven by electromigration is among the most challenging materials reliability problems in microelectronics toward ultra-large-scale integration. One of the most serious failure mechanisms in thin films with bamboo grain structure is the propagation of transgranular voids, which may lead to open-circuit failure. In this article, a comprehensive theoretical analysis is presented of the complex nonlinear dynamics of transgranular voids in metallic thin films as determined by capillarity-driven surface diffusion coupled with drift induced by electromigration. Our analysis is based on self-consistent dynamical simulations of void morphological evolution and it is aided by the conclusions of an approximate linear stability theory. Our simulations emphasize that the strong dependence of surface diffusivity on void surface orientation, the strength of the applied electric field, and the void size play important roles in the dynamics of the voids. The simulations predict void faceting, formation of wedge-shaped voids due to facet selection, propagation of slit-like features emanating from void surfaces, open-circuit failure due to slit propagation, as well as appearance and disappearance of soliton-like features on void surfaces prior to failure. These predictions are in very good agreement with recent experimental observations during accelerated electromigration testing of unpassivated metallic films. The simulation results are used to establish conditions for the formation of various void morphological features and discuss their serious implications for interconnect reliability. {copyright} {ital 1999 American Institute of Physics.}

  9. Development of a Decision Aid for Patients with Advanced Heart Failure Considering a Destination Therapy Left Ventricular Assist Device

    PubMed Central

    Thompson, Jocelyn S.; Matlock, Daniel D.; McIlvennan, Colleen K.; Jenkins, Amy R.; Allen, Larry A.

    2015-01-01

    STRUCTURED ABSTRACT Objective We aimed to create decision aids (DAs) for patients considering destination therapy left ventricular assist device (DT LVAD). Background DT LVAD is a major decision for patients with end-stage heart failure. Patients facing decisions with complex tradeoffs may benefit from high-quality decision support resources. Methods Following the International Patient Decision Aid Standards (IPDAS) guidelines and based on a needs assessment with stakeholders, we developed drafts of paper and video DAs. With input from patients, caregivers, and clinicians through alpha testing, we iteratively modified the DAs to ensure acceptability. Results We conducted semi-structured interviews with 24 patients, 20 caregivers, and 24 clinicians to assess readability, bias, and usability of the DAs. Stakeholder feedback allowed us to integrate aspects critical to decision-making around highly invasive therapies for life-threatening diseases, including addressing emotion and fear of death, using gain frames for all options that focus on living, highlighting palliative and hospice care, integrating the caregiver role, and utilizing a range of balanced testimonials. After 19 iterative versions of the paper DA and four versions of the video DA, final materials were made available for wider use. Conclusion We developed the first IPDAS-level DAs for DT LVAD. Given the extreme nature of this medical decision, we augmented traditional DA characteristics with non-traditional DA features to address a spectrum of cognitive, automatic, and emotional aspects of end-of-life decision-making. Not only are the DAs important tools for those confronting end-stage heart failure, but the lessons learned will likely inform decision support for other invasive therapies. UNSTRUCTURED ABSTRACT Destination therapy left ventricular assist device (DT LVAD) is a major decision for patients with end-stage heart failure. We aimed to create decision aids (DAs) to support patients and their

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

    SciTech Connect

    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.

  11. Progressive Failure Analysis of Advanced Composites

    DTIC Science & Technology

    2008-07-25

    subroutine SUBROUTINE UVARM(UVAR,DIRECT,T,TIME,DTIME,CMNAME,ORNAME, 1 NUVARM,NOEL,NPT,LAYER,KSPT,KSTEP,KINC,NDI,NSHR,COORD, 2 JMAC ,JMATYP,MATLAYO,LACCFLA...CHARACTER dmkname*255, FNAMEX*80 DIMENSION UVAR(*),DIRECT(3,3),T(3,3),TIME(2) DIMENSION ARRAY(15),JARRAY(15), JMAC (*),JMATYP(*),COORD(*) C DIMENSION stress(6...CALL GETVRM(’S’,ARRAY,JARRAY,FLGRAY,JRCD, JMAC ,JMATYP,MATLAYO, 1 LACCFLA) C 48 if(klarc.eq.3) then ! LaRC03 failure criteria stress(1) = array(1

  12. Failure analysis of composite laminates including biaxial compression

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Elliott, W. G.

    1983-01-01

    This report describes a continued effort on the development and application of the tensor polynomial failure criterion for composite laminate analysis. In particular, emphasis is given to the design, construction and testing of a cross-beam laminate configuration to obtain "pure' biaxial compression failure. The purpose of this test case was to provide to permit "closure' of the cubic form of the failure surface in the 1-2 compression-compression quadrant. This resulted in a revised set of interaction strength parameters and the construction of a failure surface which can be used with confidence for strength predictions, assuming a plane stress state exists. Furthermore, the problem of complex conjugate roots which can occur in some failure regions is addressed and an "engineering' interpretation is provided. Results are presented illustrating this behavior and the methodology for overcoming this problem is discussed.

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

    SciTech Connect

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

    1996-11-01

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

  14. MOVANAID: An Interactive Aid for Analysis of Movement Capabilities.

    ERIC Educational Resources Information Center

    Cooper, George E.; And Others

    A computer-drive interactive aid for movement analysis, called MOVANAID, has been developed to be of assistance in the performance of certain Army intelligence processing tasks in a tactical environment. It can compute fastest travel times and paths through road networks for military units of various types, as well as fastest times in which…

  15. Failure of the ERBE scanner instrument aboard NOAA 10 spacecraft and results of failure analysis

    NASA Technical Reports Server (NTRS)

    Miller, J. B.; Weaver, W. L.; Kopia, L. P.; Howerton, C. E.; Payton, M. G.; Harris, C. J.

    1990-01-01

    The Earth Radiation Budget Experiment (ERBE) scanner instrument on the NOAA 10 spacecraft malfunctioned on May 22, 1989, after more than 4 years of in-flight operation. After the failure, all instrument operational mode commands were tested and the resulting data analyzed. Details of the tests and analysis of output data are discussed therein. The radiometric and housekeeping data appear to be valid. However, the instrument will not correctly execute operational scan mode commands or the preprogrammed calibration sequences. The data indicate the problem is the result of a failure in the internal address decoding circuity in one of the ROM (read only memory) chips of the instrument computer.

  16. Synthesis Sheets: An Aid To Synthetic Analysis

    ERIC Educational Resources Information Center

    Still, W. Clark

    1973-01-01

    Describes the development of a scheme which allows the production of a complete synthesis tree through the backward analysis of a target molecule into precursor and pathway catalogues. The logical organizing framework will find applications to teaching of multistep organic synthesis. (CC)

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Failure Mode Effects Analysis for an Accelerator Control System

    SciTech Connect

    Hartman, Steven M

    2009-01-01

    Failure mode effects analysis (FMEA) has been used in industry for design, manufacturing and assembly process quality control. It describes a formal approach for categorizing how a process may fail and for prioritizing failures based on their severity, frequency and likelihood of detection. Experience conducting a partial FMEA of an accelerator subsystem and its related control system will be reviewed. The applicability of the FMEA process to an operational accelerator control system will be discussed.

  20. Computational Methods for Failure Analysis and Life Prediction

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K. (Compiler); Harris, Charles E. (Compiler); Housner, Jerrold M. (Compiler); Hopkins, Dale A. (Compiler)

    1993-01-01

    This conference publication contains the presentations and discussions from the joint UVA/NASA Workshop on Computational Methods for Failure Analysis and Life Prediction held at NASA Langley Research Center 14-15 Oct. 1992. The presentations focused on damage failure and life predictions of polymer-matrix composite structures. They covered some of the research activities at NASA Langley, NASA Lewis, Southwest Research Institute, industry, and universities. Both airframes and propulsion systems were considered.

  1. Failure analysis of a Stirling engine heat pipe

    NASA Technical Reports Server (NTRS)

    Moore, Thomas J.; Cairelli, James E.; Khalili, Kaveh

    1989-01-01

    Failure analysis was conducted on a heat pipe from a Stirling Engine test rig which was designed to operate at 1073 K. Premature failure had occurred due to localized overheating at the leading edge of the evaporator fin. It was found that a crack had allowed air to enter the fin and react with the sodium coolant. The origin of the crack was found to be located at the inner surface of the Inconel 600 fin where severe intergranular corrosion had taken place.

  2. A Computer Aided Statistical Covariance Program for Missile System Analysis

    DTIC Science & Technology

    1974-04-01

    ENGINEERING RESEARCH OKLAHOMA STATE UNIVERSITY A COMPUTER AIDED STATISTICAL COVARIANCE PROGRAM FOR MISSILE SYSTEM ANALYSI. TO D JN2 U. S. Army Missile...ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK AREA & WORK UNIT NUMBERS Office of Engineering Rsch, Oklahoma State Univ Agiculture...ANALYSIS by James R. Rowland and V. M. Gupta School of Electrical Engineering V Approved for public release; distribution unlimited. Office of Engineering

  3. Renal syndromes in the acquired immunodeficiency syndrome (AIDS): lessons learned from analysis over 5 years.

    PubMed

    Rao, T K; Friedman, E A

    1988-06-01

    Renal syndromes associated with the Acquired immunodeficiency syndrome include: potentially reversible acute renal failure, AIDS associated nephropathy which leads to end stage renal disease, and AIDS developing in patients who are being treated by maintenance hemodialysis. The longitudinal study of 95 patients with AIDS and various forms of renal syndrome at two urban institutions indicates that both acute and chronic renal failure is increasing yearly. While some patients with acute renal failure recover renal function and survive for prolonged period, the mortality of dialyzed patients with irreversible renal failure continues to be unsatisfactory. There is a great need for collecting data from high risk areas to analyze the results of maintenance dialysis therapy in patients with AIDS, to assess the economic impact of uremia therapy, and for long-term planning of available resources.

  4. SOLERAS: Photovoltaic power systems project. Module failure analysis

    NASA Astrophysics Data System (ADS)

    Huraib, F. S.; Imamura, M. S.; Salim, A. A.; Rao, N.

    1984-10-01

    The SOLERAS Photovoltaic Power System (PVPS) became operational in September 1981. The system has operated satisfactorily and has experienced very little downtime. Early in 1983 some degradation in the photovoltaic (PV) field performance was detected. A series of current voltage (I-V) tests and other analyses eventually uncovered a number of PV modules that have resulted in open circuit type failure in the four cell group, or a half module. As of August 1984, the estimated number of these defective modules in the PV field was 152. In addition, there are a total of 188 defective modules in the storage warehouse, resulting in a total of 340 modules that need repairs. At the current rate of failures (seven half modules per month), an additional 112 modules would be defective by the end of January 1986, resulting in 412 defective modules. This report presents the results of the failure analysis performed during the past several months on the open circuit modules. Background information as related to the module failures and the effects of such failures on the overall PV field power output are provided. In addition, a plan to continue the monitoring of the rate of failure and analyzing the failure mechanisms is presented.

  5. Using Failure Information Analysis to Detect Enterprise Zombies

    NASA Astrophysics Data System (ADS)

    Zhu, Zhaosheng; Yegneswaran, Vinod; Chen, Yan

    We propose failure information analysis as a novel strategy for uncovering malware activity and other anomalies in enterprise network traffic. A focus of our study is detecting self-propagating malware such as worms and botnets. We begin by conducting an empirical study of transport- and application-layer failure activity using a collection of long-lived malware traces. We dissect the failure activity observed in this traffic in several dimensions, finding that their failure patterns differ significantly from those of real-world applications. Based on these observations, we describe the design of a prototype system called Netfuse to automatically detect and isolate malware-like failure patterns. The system uses an SVM-based classification engine to identify suspicious systems and clustering to aggregate failure activity of related enterprise hosts. Our evaluation using several malware traces demonstrates that the Netfuse system provides an effective means to discover suspicious application failures and infected enterprise hosts. We believe it would be a useful complement to existing defenses.

  6. [Analysis of anti-reflux surgery failure].

    PubMed

    Cano Novillo, I; Benavent Gordo, M I; Portela Casalod, E; Delgado Muñoz, M D; Aguado Roncero, P; Vilariño Mosquera, A; Berchi García, F J

    2000-01-01

    Recurrent gastroesophageal reflux following fundoplication is a challenging problem, because it is usually refractory to medical treatment and a second, technically difficult, antireflux operation is required. Different factors that may contribute to surgery failure have been identified in children. We present 8 cases who underwent redofundoplication after failed procedures, from a total number of 96 patients operated on due to gastroesophageal reflux. Four patient's had their initial fundoplication performed at our institution. Six patients were neurologically impaired, six had chronic pulmonary disease, and two had esophageal atresia. The main presenting symptoms were recurrent vomiting (n = 8) and aspiration (n = 4). Gastroesophageal reflux was confirmed by barium swallow and endoscopy. Operative findings showed wrap breakdown in two cases, warp breakdown associated with hiatal hernia in five, wrap breakdown associated with paraesophageal hernia in two cases, and paraesophageal hernia with normal wrap in one. A second Nissen procedure were performed in five cases, whereas a Collis-Nissen gastroplasty was realized in three with a short esophagus. Six patients had a successful outcome remaining symptom free, one has severe disphagia, and one has recurrent vomiting. In our experience, patients with recurrent gastroesophageal reflux disease should undergo an antireflux procedure tailored to specific anatomic or functional abnormalities.

  7. Ambient-temperature creep failure of silver-aided diffusion bonds between steel

    SciTech Connect

    Henshall, G.A.; Kassner, M.E.; Rosen, R.S.

    1990-01-15

    It has long been known that thin (e.g., 1 {mu}m {minus} 1 mm) interlayer bonds between higher strength base materials may have high ultimate tensile or rupture strengths despite the relatively low strength of the filler metal. The high strength of the joint is due to the mechanical constraint provided by the stronger base metals which restricts transverse contraction of the interlayer. The constraint produces a triaxial state or stress and reduces the effective stress, thus reducing the tendency for the interlayer to plastically deform. Plasticity of the base metal reduces the constraint and decreases the strength of the bond. The purpose of this work was twofold. First, the validity of the base-metal- accelerated'' delayed-failure theory for bonds utilizing plastic base metals was checked. Creep-rupture tests were performed on diffusion-bonded specimens using silver interlayers deposited by planar-magnetron sputtering (PMS), a physical vapor-deposition process. The PMS process was preferred because of the superior quality and strength of the bond and because this modern low-temperature joining process is increasingly utilized for joining ceramic and composite materials. The role of plastic base metals in the fracture process was further investigated by conducting tensile-rupture tests of diffusion bonds made with stainless steel base metals of different yield strengths, and therefore different creep rates. The second purpose was to determine whether delayed failure occurs in interlayer bonds between elastic base metals, which do not creep over the range of applied stresses. This question is particularly relevant since many alloys, ceramics and composites fall within this category. Again, ambient and near-ambient temperature creep-rupture tests were performed at a variety of stresses below the UTS of the bond. 25 refs., 7 figs.

  8. Launch Vehicle Failure Dynamics and Abort Triggering Analysis

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  9. Failure analysis of thick composite cylinders under external pressure

    NASA Technical Reports Server (NTRS)

    Caiazzo, A.; Rosen, B. W.

    1992-01-01

    Failure of thick section composites due to local compression strength and overall structural instability is treated. Effects of material nonlinearity, imperfect fiber architecture, and structural imperfections upon anticipated failure stresses are determined. Comparisons with experimental data for a series of test cylinders are described. Predicting the failure strength of composite structures requires consideration of stability and material strength modes of failure using linear and nonlinear analysis techniques. Material strength prediction requires the accurate definition of the local multiaxial stress state in the material. An elasticity solution for the linear static analysis of thick anisotropic cylinders and rings is used herein to predict the axisymmetric stress state in the cylinders. Asymmetric nonlinear behavior due to initial cylinder out of roundness and the effects of end closure structure are treated using finite element methods. It is assumed that local fiber or ply waviness is an important factor in the initiation of material failure. An analytical model for the prediction of compression failure of fiber composites, which includes the effects of fiber misalignments, matrix inelasticity, and multiaxial applied stresses is used for material strength calculations. Analytical results are compared to experimental data for a series of glass and carbon fiber reinforced epoxy cylinders subjected to external pressure. Recommendations for pretest characterization and other experimental issues are presented. Implications for material and structural design are discussed.

  10. Use of failure mode and effects analysis for proactive identification of communication and handoff failures from organ procurement to transplantation.

    PubMed

    Steinberger, Dina M; Douglas, Stephen V; Kirschbaum, Mark S

    2009-09-01

    A multidisciplinary team from the University of Wisconsin Hospital and Clinics transplant program used failure mode and effects analysis to proactively examine opportunities for communication and handoff failures across the continuum of care from organ procurement to transplantation. The team performed a modified failure mode and effects analysis that isolated the multiple linked, serial, and complex information exchanges occurring during the transplantation of one solid organ. Failure mode and effects analysis proved effective for engaging a diverse group of persons who had an investment in the outcome in analysis and discussion of opportunities to improve the system's resilience for avoiding errors during a time-pressured and complex process.

  11. Is Computer-Aided Instruction an Effective Tier-One Intervention for Kindergarten Students at Risk for Reading Failure in an Applied Setting?

    ERIC Educational Resources Information Center

    Kreskey, Donna DeVaughn; Truscott, Stephen D.

    2016-01-01

    This study investigated the use of computer-aided instruction (CAI) as an intervention for kindergarten students at risk for reading failure. Headsprout Early Reading (Headsprout 2005), a type of CAI, provides internet-based, reading instruction incorporating the critical components of reading instruction cited by the National Reading Panel (NRP…

  12. S Tank Farm SL-119 saltwell piping failure analysis report

    SciTech Connect

    Carlos, W.C.

    1994-08-05

    On January 24, 1992, while pressure testing saltwell line SL-119 in the 241-S Tank Farm, water was observed spraying out of heat trace enclosure. The SL-115, SL-116, SN-215, and SN-216 saltwell lines also recently failed pressure testing because of leaks. This study documents the pertinent facts about the SL-119 line and discusses the cause of the failures. The inspection of the SL-119 failure revealed two through-the-wall holes in the top center of the pipeline. The inspection also strongly suggests that the heat tracing system is directly responsible for causing the SL-119 failure. Poor design of the heat tracing system allowed water to enter, condense, and collect in the electric metallic tubing (EMT) carbon steel conduits. Water flowed to the bottom of the elbow of the conduit and corroded out the elbow. The design also allowed drifting desert sand to enter into the conduit and fall to the bottom (elbow) of the conduit. The sand became wet and aided in the corrosion of the elbow of the conduit. After the EMT conduits corroded though, the water dripped from the corroded ends of the EMT conduits onto the top of the saltwell pipe, corroding the two holes into the top of the line. If the heat tracing hot splice box had not allowed moisture to enter the EMT conduits, the saltwell piping would not have corroded and caused SL-119 to fail.

  13. Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures

    DTIC Science & Technology

    2005-03-01

    respect to the nominal alloy composition at the center of weld surface (Point 6 of Figure 7) -21 - U CO 2000 - * cE axc -2000 o" "....". . -401.11𔃺 1󈧄...Final Report Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures Office of Naval Research 800 North Quincy Street Arlington...3/31/05 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Sensitivity Analysis for Dynamic Failure and Damage in Metallic Structures Sb. GRANT NUMBER N000

  14. Failure mode analysis of a spacecraft power system

    SciTech Connect

    Lee, J.R.

    1995-12-31

    For the spacecraft power system`s dynamic analyses, dc/dc converters are usually modeled with a linearized model using the state space averaging technique. The linearized model can be used for small-signal ac and transient analyses. However, since the linearized model has limitations in its accuracies, certain types of transient analyses including a failure mode must be performed by using a more accurate cycle-by-cycle model. In this paper, a failure mode analysis is presented with a small-signal analysis and corresponding transient simulations.

  15. Failure Analysis of Space Shuttle Orbiter Valve Poppet

    NASA Technical Reports Server (NTRS)

    Russell, Rick

    2010-01-01

    The poppet failed during STS-126 due to fatigue cracking that most likely was initiated during MDC ground-testing. This failure ultimately led to the discovery that the cracking problem was a generic issue effecting numerous poppets throughout the Shuttle program's history. This presentation has focused on the laboratory analysis of the failed hardware, but this analysis was only one aspect of a comprehensive failure investigation. One critical aspect of the overall investigation was modeling of the fluid flow through this valve to determine the possible sources of cyclic loading. This work has led to the conclusion that the poppets are failing due to flow-induced vibration.

  16. Analysis of the shearout failure mode in composite bolted joints

    NASA Technical Reports Server (NTRS)

    Wilson, D. W.; Pipes, R. B.

    1981-01-01

    A semi-empirical shearout strength model has been formulated for the analysis of composite bolted joints with allowance for the effects of joint geometry. The model employs a polynomial stress function in conjunction with a point stress failure criterion to predict strength as a function of fastener size, edge distance, and half spacing. The stress function is obtained by two-dimensional plane-stress finite element analysis using quadrilateral elements with orthotropic material properties. Comparison of experimentally determined shearout strength data with model predicted failures has substantiated the accuracy of the model.

  17. The quantitative failure of human reliability analysis

    SciTech Connect

    Bennett, C.T.

    1995-07-01

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

  18. Failure modes and effects analysis of fusion magnet systems

    SciTech Connect

    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.

  19. Failure analysis of a tool-steel torque shaft

    SciTech Connect

    Reagan, J.R.

    1981-01-01

    A low design load drive shaft from an experimental diesel truck engine failed unexpectedly during highway testing. The shaft was driven by a turbine used to deliver power from an experimental exhaust heat recovery system to the engine's crankshaft. During design, fatigue was not considered a major problem because of the low operating cyclic stresses. An independent testing laboratory analyzed the failure by routine metallography. The structure of the hardened S-7 tool steel shaft was banded and the laboratory attributed the failure to fatigue induced by a banded microstructure. NASA was asked to confirm this analysis. Visual examination of the failed shaft plus the knowledge of the torsional load that it carried pointed to a 100% ductile failure with no evidence of fatigue. Scanning electron microscopy confirmed this. Torsional test specimens were produced from pieces of the failed shaft and torsional overload testing produced identical failures to that which had occurred in the truck engine. This pointed to a failure caused by a high overload and although the microstructure was defective it was not the cause of the failure.

  20. Statistical analysis of cascading failures in power grids

    SciTech Connect

    Chertkov, Michael; Pfitzner, Rene; Turitsyn, Konstantin

    2010-12-01

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

  1. Reliability-based failure analysis of brittle materials

    NASA Technical Reports Server (NTRS)

    Powers, Lynn M.; Ghosn, Louis J.

    1989-01-01

    The reliability of brittle materials under a generalized state of stress is analyzed using the Batdorf model. The model is modified to include the reduction in shear due to the effect of the compressive stress on the microscopic crack faces. The combined effect of both surface and volume flaws is included. Due to the nature of fracture of brittle materials under compressive loading, the component is modeled as a series system in order to establish bounds on the probability of failure. A computer program was written to determine the probability of failure employing data from a finite element analysis. The analysis showed that for tensile loading a single crack will be the cause of total failure but under compressive loading a series of microscopic cracks must join together to form a dominant crack.

  2. 21 CFR 874.3310 - Hearing aid calibrator and analysis system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Hearing aid calibrator and analysis system. 874.3310 Section 874.3310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... aid calibrator and analysis system. (a) Identification. A hearing aid calibrator and analysis...

  3. 21 CFR 874.3310 - Hearing aid calibrator and analysis system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Hearing aid calibrator and analysis system. 874.3310 Section 874.3310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... aid calibrator and analysis system. (a) Identification. A hearing aid calibrator and analysis...

  4. 21 CFR 874.3310 - Hearing aid calibrator and analysis system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Hearing aid calibrator and analysis system. 874.3310 Section 874.3310 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... aid calibrator and analysis system. (a) Identification. A hearing aid calibrator and analysis...

  5. Failure analysis of solid rocket apogee motors

    NASA Technical Reports Server (NTRS)

    Martin, P. J.

    1972-01-01

    The analysis followed five selected motors through initial design, development, test, qualification, manufacture, and final flight reports. An audit was conducted at the manufacturing plants to complement the literature search with firsthand observations of the current philosophies and practices that affect reliability of the motors. A second literature search emphasized acquisition of spacecraft and satellite data bearing on solid motor reliability. It was concluded that present practices at the plants yield highly reliable flight hardware. Reliability can be further improved by new developments of aft-end bonding and initiator/igniter nondestructive test methods, a safe/arm device, and an insulation formulation. Minimum diagnostic instrumentation is recommended for all motor flights. Surplus motors should be used in margin testing. Criteria should be established for pressure and zone curing. The motor contractor should be represented at launch. New design analyses should be made of stretched motors and spacecraft/motor pairs.

  6. Space Shuttle Columbia Aging Wiring Failure Analysis

    NASA Technical Reports Server (NTRS)

    McDaniels, Steven J.

    2005-01-01

    A Space Shuttle Columbia main engine controller 14 AWG wire short circuited during the launch of STS-93. Post-flight examination divulged that the wire had electrically arced against the head of a nearby bolt. More extensive inspection revealed additional damage to the subject wire, and to other wires as well from the mid-body of Columbia. The shorted wire was to have been constructed from nickel-plated copper conductors surrounded by the polyimide insulation Kapton, top-coated with an aromatic polyimide resin. The wires were analyzed via scanning electron microscope (SEM), energy dispersive X-Ray spectroscopy (EDX), and electron spectroscopy for chemical analysis (ESCA); differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA) were performed on the polyimide. Exemplar testing under laboratory conditions was performed to replicate the mechanical damage characteristics evident on the failed wires. The exemplar testing included a step test, where, as the name implies, a person stepped on a simulated wire bundle that rested upon a bolt head. Likewise, a shear test that forced a bolt head and a torque tip against a wire was performed to attempt to damage the insulation and conductor. Additionally, a vibration test was performed to determine if a wire bundle would abrade when vibrated against the head of a bolt. Also, an abrasion test was undertaken to determine if the polyimide of the wire could be damaged by rubbing against convolex helical tubing. Finally, an impact test was performed to ascertain if the use of the tubing would protect the wire from the strike of a foreign object.

  7. Bank stability analysis for fluvial erosion and mass failure

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  8. Analysis of Search Failures in Document Retrieval Systems: A Review.

    ERIC Educational Resources Information Center

    Tonta, Yasar

    1992-01-01

    Discusses the concept of search failure in document retrieval systems and three effectiveness measures, precision, recall, and "fallout." Four research methods--retrieval effectiveness measures, user satisfaction measures, transaction log analysis, and critical incident technique--are examined, and findings of major studies using each of the…

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

    PubMed

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

    2012-01-01

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

  10. Analysis of nuclear power plant component failures

    SciTech Connect

    Not Available

    1984-01-01

    Items are shown that have caused 90% of the nuclear unit outages and/or deratings between 1971 and 1980 and the magnitude of the problem indicated by an estimate of power replacement cost when the units are out of service or derated. The funding EPRI has provided on these specific items for R and D and technology transfer in the past and the funding planned in the future (1982 to 1986) are shown. EPRI's R and D may help the utilities on only a small part of their nuclear unit outage problems. For example, refueling is the major cause for nuclear unit outages or deratings and the steam turbine is the second major cause for nuclear unit outages; however, these two items have been ranked fairly low on the EPRI priority list for R and D funding. Other items such as nuclear safety (NRC requirements), reactor general, reactor and safety valves and piping, and reactor fuel appear to be receiving more priority than is necessary as determined by analysis of nuclear unit outage causes.

  11. Stress analysis during slope failure from DEM simulations

    NASA Astrophysics Data System (ADS)

    Katz, O.; Morgan, J. K.

    2012-04-01

    We used Discrete Element Method (DEM) simulations to study the initiation and evolution of landsliding, with a focus on the development and propagation of the sliding plane, and on the effects of material strength on the behavior of the slope material during landsliding. Our simulated slopes were constructed of homogeneous materials, settled under gravity, bonded, and excavated to produce 70 deg slopes of 1050 m in height. Nine simulations were carried out, each using a different value of cohesions, ranging from 0.7 to 4.2 MPa (quantified through DEM direct shear simulations on representative materials). In each of our simulations, failure initiated at the foot of the slope, accompanied by disintegration of the slope material. Failure then propagated upward to the slope crest with further material disintegration. A discrete detachment surface formed below the disintegrated material. Downslope movement of the failed material (i.e. landsliding) occurred only after the failure plane intersected the upper slope face. By the end of landsliding, the disintegrated slope material formed a talus like deposit at the foot of the slope. The value of initial material cohesion influenced the nature of the landslide deposit and its dimension. Higher material strengths produced smaller landslides, as well as the occurrence of discrete landslide blocks, which originated from the shallow slopes, and became entrained within the finer talus. Stress analysis of the slope failure process clarifies how failure initiates and landsliding evolves, and further constrains the limiting failure criteria that define each simulated material. The local proximity to failure throughout the slope can be tracked during the simulation, revealing that high failure potential (high shear stress relative to mean stress) exists at the toe of the slope immediately following excavation. As material disintegrates near the toe of the slope, high tensile stresses develop in the overlying mass, causing the break

  12. 3D statistical failure analysis of monolithic dental ceramic crowns.

    PubMed

    Nasrin, Sadia; Katsube, Noriko; Seghi, Robert R; Rokhlin, Stanislav I

    2016-07-05

    For adhesively retained ceramic crown of various types, it has been clinically observed that the most catastrophic failures initiate from the cement interface as a result of radial crack formation as opposed to Hertzian contact stresses originating on the occlusal surface. In this work, a 3D failure prognosis model is developed for interface initiated failures of monolithic ceramic crowns. The surface flaw distribution parameters determined by biaxial flexural tests on ceramic plates and point-to-point variations of multi-axial stress state at the intaglio surface are obtained by finite element stress analysis. They are combined on the basis of fracture mechanics based statistical failure probability model to predict failure probability of a monolithic crown subjected to single-cycle indentation load. The proposed method is verified by prior 2D axisymmetric model and experimental data. Under conditions where the crowns are completely bonded to the tooth substrate, both high flexural stress and high interfacial shear stress are shown to occur in the wall region where the crown thickness is relatively thin while high interfacial normal tensile stress distribution is observed at the margin region. Significant impact of reduced cement modulus on these stress states is shown. While the analyses are limited to single-cycle load-to-failure tests, high interfacial normal tensile stress or high interfacial shear stress may contribute to degradation of the cement bond between ceramic and dentin. In addition, the crown failure probability is shown to be controlled by high flexural stress concentrations over a small area, and the proposed method might be of some value to detect initial crown design errors.

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

    SciTech Connect

    Huq, M.

    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

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

    PubMed

    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.

  15. Design, Fabrication and Failure Analysis of Stretchable Electrical Routings

    PubMed Central

    Hocheng, Hong; Chen, Chao-Ming

    2014-01-01

    Stretchable microelectromechanical systems (MEMS) possess higher mechanical deformability and adaptability than devices based on conventional solid and flexible substrates, hence they are particularly desirable for biomedical, optoelectronic, textile and other innovative applications. The stretchability performance can be evaluated by the failure strain of the embedded routing and the strain applied to the elastomeric substrate. The routings are divided into five forms according to their geometry: straight; wavy; wrinkly; island-bridge; and conductive-elastomeric. These designs are reviewed and their resistance-to-failure performance is investigated. The failure modeling, numerical analysis, and fabrication of routings are presented. The current review concludes with the essential factors of the stretchable electrical routing for achieving high performance, including routing angle, width and thickness. The future challenges of device integration and reliability assessment of the stretchable routings are addressed. PMID:24999718

  16. Analysis of valve failures from the NUCLARR data base

    SciTech Connect

    Moore, L.M.

    1997-11-01

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

  17. Acoustic emission spectral analysis of fiber composite failure mechanisms

    NASA Technical Reports Server (NTRS)

    Egan, D. M.; Williams, J. H., Jr.

    1978-01-01

    The acoustic emission of graphite fiber polyimide composite failure mechanisms was investigated with emphasis on frequency spectrum analysis. Although visual examination of spectral densities could not distinguish among fracture sources, a paired-sample t statistical analysis of mean normalized spectral densities did provide quantitative discrimination among acoustic emissions from 10 deg, 90 deg, and plus or minus 45 deg, plus or minus 45 deg sub s specimens. Comparable discrimination was not obtained for 0 deg specimens.

  18. Statistical analysis of barrier isolator/glovebox glove failure.

    PubMed

    Park, Young H; Pines, E; Ofouku, M; Cournoyer, M E

    2007-01-01

    In response to new, stricter safety requirements set out by the federal government, compounding pharmacists are investigating applications and processes appropriate for their facilities. One application, cutrrently used by many industries, was developed by Los Alamos National Laboratories for defense work. A barrier isolator or "glovebox" is a containment device that allows work within a sealed space while providing protection for people and the environment. Though knowledge of glove box use and maintenance has grown, unplanned breaches (e.g., glove failures) remain a concern. Recognizing that effective maintenance procedures can minimize breaches, we analyzed data drawn from glove failure records of Los Alamos National Laboratory's Nuclear Materials Technology Division to evaluate current inventory strategy in light of actual performance of the various types of gloves. This report includes a description of the statistical methods employed. The results of our analysis pinpointed the most frequently occurring causes of glove failure and revealed a significant imbalance between the current glove replacement schedule and the rate of glove failures in a much shorter period. We concluded that, to minimize unplanned breaches, either the replacement period needs to be adjusted or causes of failure eliminated or reduced.

  19. Failure analysis for micro-electrical-mechanical systems (MEMS)

    SciTech Connect

    Peterson, K.A.; Tangyunyong, P.; Barton, D.L.

    1997-10-01

    Micro-Electrical Mechanical Systems (MEMS) is an emerging technology with demonstrated potential for a wide range of applications including sensors and actuators for medical, industrial, consumer, military, automotive and instrumentation products. Failure analysis (FA) of MEMS is critically needed for the successful design, fabrication, performance analysis and reliability assurance of this new technology. Many devices have been examined using techniques developed for integrated circuit analysis, including optical inspection, scanning laser microscopy (SLM), scanning electron microscopy (SEM), focused ion beam (FIB) techniques, atomic force microscopy (AFM), infrared (IR) microscopy, light emission (LE) microscopy, acoustic microscopy and acoustic emission analysis. For example, the FIB was used to microsection microengines that developed poor performance characteristics. Subsequent SEM analysis clearly demonstrated the absence of wear on gear, hub, and pin joint bearing surfaces, contrary to expectations. Another example involved the use of infrared microscopy for thermal analysis of operating microengines. Hot spots were located, which did not involve the gear or hub, but indicated contact between comb structures which drive microengines. Voltage contrast imaging proved useful on static and operating MEMS in both the SEM and the FIB and identified electrostatic clamping as a potentially significant contributor to failure mechanisms in microengines. This work describes MEMS devices, FA techniques, failure modes, and examples of FA of MEMS.

  20. Multidisciplinary Expert-aided Analysis and Design (MEAD)

    NASA Technical Reports Server (NTRS)

    Hummel, Thomas C.; Taylor, James

    1989-01-01

    The MEAD Computer Program (MCP) is being developed under the Multidisciplinary Expert-Aided Analysis and Design (MEAD) Project as a CAD environment in which integrated flight, propulsion, and structural control systems can be designed and analyzed. The MCP has several embedded computer-aided control engineering (CACE) packages, a user interface (UI), a supervisor, a data-base manager (DBM), and an expert system (ES). The supervisor monitors and coordinates the operation of the CACE packages, the DBM; the ES, and the UI. The DBM tracks the control design process. Models created or installed by the MCP are tracked by date and version, and results are associated with the specific model version with which they were generated. The ES is used to relieve the control engineer from tedious and cumbersome tasks in the iterative design process. The UI provides the capability for a novice as well as an expert to utilize the MCP easily and effectively. The MCP version 2(MCP-2.0) is fully developed for flight control system design and analysis. Propulsion system modeling, analysis, and simulation is also supported; the same is true for structural models represented in state-space form. The ultimate goal is to cover the integration of flight, propulsion, and structural control engineering, including all discipline-specific functionality and interfaces. The current MCP-2.0 components and functionality are discussed.

  1. Financial Aid Tipping Points: An Analysis of Aid and Academic Achievement at a California Community College

    ERIC Educational Resources Information Center

    Coria, Elizabeth; Hoffman, John L.

    2016-01-01

    The purpose of this study was to explore relationships between financial aid awards and measures of student academic achievement. Financial aid and academic records for 11,956 students attending an urban California community college were examined and analyzed using simultaneous linear regression and two-way factorial ANOVAs. Findings revealed a…

  2. Evaluation of a Progressive Failure Analysis Methodology for Laminated Composite Structures

    NASA Technical Reports Server (NTRS)

    Sleight, David W.; Knight, Norman F., Jr.; Wang, John T.

    1997-01-01

    A progressive failure analysis methodology has been developed for predicting the nonlinear response and failure of laminated composite structures. The progressive failure analysis uses C plate and shell elements based on classical lamination theory to calculate the in-plane stresses. Several failure criteria, including the maximum strain criterion, Hashin's criterion, and Christensen's criterion, are used to predict the failure mechanisms. The progressive failure analysis model is implemented into a general purpose finite element code and can predict the damage and response of laminated composite structures from initial loading to final failure.

  3. Failure analysis of an Oregon coast reinforced concrete bridge

    SciTech Connect

    Holcomb, Gordon R.; Covino, Bernard S., Jr.; Cramer, Stephen D.; Bullard, Sophie J.; Russell, James H.; Soltesz, S.M.

    2001-01-01

    The coastal highway along the Oregon coast contains many reinforced concrete bridges constructed between 1925 and 1955. Chloride-induced corrosion resulted in the need for the rehabilitation or replacement of a number of these bridges. A failure analysis of the Rocky Point Viaduct (built in 1954, patched in 1969, replaced in 1994) is presented. Analysis included powder sampling and profiling of Cl concentration, determining the permeable void fraction in the concrete, and measuring rebar half cell potentials. Insufficient concrete cover over the shear stirrups was the major factor in the premature failure of the Viaduct. The time required for corrosion initiation and cracking was modeled by calculating diffusion parameters (surface Cl concentration (Co) and diffusion coefficient (D)) from Cl profiles. The model was used to examine the relative ineffectiveness of the patch repairs by showing increased Cl transport in the patch due to both higher Co and D values.

  4. Failure analysis of a half-micron CMOS IC technology

    SciTech Connect

    Liang, A.Y.; Tangyunyong, P.; Bennett, R.S.; Flores, R.S.

    1996-08-01

    We present the results of recent failure analysis of an advanced, 0.5 {mu}m, fully planarized, triple metallization CMOS technology. A variety of failure analysis (FA) tools and techniques were used to localize and identify defects generated by wafer processing. These include light (photon) emission microscopy (LE), fluorescent microthermal imaging (FMI), focused ion beam cross sectioning, SEM/voltage contrast imaging, resistive contrast imaging (RCI), and e-beam testing using an IDS-5000 with an HP 82000. The defects identified included inter- and intra-metal shorts, gate oxide shorts due to plasma processing damage, and high contact resistance due to the contact etch and deposition process. Root causes of these defects were determined and corrective action was taken to improve yield and reliability.

  5. Seismic analysis for translational failure of landfills with retaining walls.

    PubMed

    Feng, Shi-Jin; Gao, Li-Ya

    2010-11-01

    In the seismic impact zone, seismic force can be a major triggering mechanism for translational failures of landfills. The scope of this paper is to develop a three-part wedge method for seismic analysis of translational failures of landfills with retaining walls. The approximate solution of the factor of safety can be calculated. Unlike previous conventional limit equilibrium methods, the new method is capable of revealing the effects of both the solid waste shear strength and the retaining wall on the translational failures of landfills during earthquake. Parameter studies of the developed method show that the factor of safety decreases with the increase of the seismic coefficient, while it increases quickly with the increase of the minimum friction angle beneath waste mass for various horizontal seismic coefficients. Increasing the minimum friction angle beneath the waste mass appears to be more effective than any other parameters for increasing the factor of safety under the considered condition. Thus, selecting liner materials with higher friction angle will considerably reduce the potential for translational failures of landfills during earthquake. The factor of safety gradually increases with the increase of the height of retaining wall for various horizontal seismic coefficients. A higher retaining wall is beneficial to the seismic stability of the landfill. Simply ignoring the retaining wall will lead to serious underestimation of the factor of safety. Besides, the approximate solution of the yield acceleration coefficient of the landfill is also presented based on the calculated method.

  6. Measurement and Analysis of Failures in Computer Systems

    NASA Technical Reports Server (NTRS)

    Thakur, Anshuman

    1997-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Vencl, Aleksandar; Gašić, Vlada; Stojanović, Blaža

    2017-02-01

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

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

    PubMed

    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.

  9. Defining Human Failure Events for Petroleum Risk Analysis

    SciTech Connect

    Ronald L. Boring; Knut Øien

    2014-06-01

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

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

    PubMed Central

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

    2015-01-01

    This topic review employed Walker and Avant’s method of concept analysis to explore the construct of hope in elderly adults with chronic heart failure. The articles analyzed revealed that hope, as the belief of the occurrence of a positive result without any guarantee that it will be produced, is necessary for the survival and wellbeing of the elderly adults enduring this disease. PMID:26321777

  11. A needs analysis for computer-based telephone triage in a community AIDS clinic.

    PubMed Central

    Henry, S. B.; Schreiner, J. G.; Borchelt, D.; Musen, M. A.

    1992-01-01

    This study describes the complexity of the telephone-triage task in a community-based AIDS clinic. We identify deficiencies related to the data management for and documentation of the telephone-triage encounter, including inaccessibility of the medical record and failure to document required data elements. Our needs analysis suggests five design criteria for a computer-based system that assists nurses with the telephone-triage task: (1) online accessibility of the medical record, (2) ability to move among modules of the medical record and the triage-encounter module, (3) ease of data entry, (4) compliance with standards for documentation, and (5) notification of the primary-care physician in an appropriate and timely manner. PMID:1482941

  12. HIV/AIDS counseling: analysis based on Paulo Freire.

    PubMed

    Miranda, Karla Corrêa Lima; Barroso, Maria Grasiela Teixeira

    2007-01-01

    The study aimed to investigate the strategies health professionals use in HIV/AIDS counseling. This study is a qualitative research, based on Paulo Freire's theory and practice. Bardin's content analysis was used as the analysis technique. For the studied group, the counseling is focused on cognition, although new concepts permeating this subject are emerging. The main difficulties in counseling are related to the clients and the institution. The main facility is related to the team, which according to the group has a good relationship. Counseling represents a moment of distress, especially because it brings up existential questions to the counselor. It can be inferred that counseling is a special moment, but it does not constitute an educational moment yet. To obtain this goal, a counseling methodology is proposed, based on Paulo Freire's principles and concepts.

  13. Transactional Analysis of Communication Styles in HIV/AIDS Advertisements.

    PubMed

    Maclachlan, M; Carr, S C; Fardell, S; Maffesoni, G; Cunningham, J

    1997-01-01

    Television advertising has been an important medium for health promotion campaigns addressing HIV/AIDS. This study sought to evaluate the 'Grim Reaper' and 'Multiple Beds' advertisements frequently broadcasted throughout Australia. Our model for evaluation was based on a theoretical synthesis of television advertising, transactional analysis (TA) and recall congruence. Eighty-three participants viewed each advertisement and rated which ego state the source of the message was attempting to 'hook' in the audience. They also predicted their own ego state during sexual intercourse and rated the effectiveness of the advertisements. As predicted by TA theory, a crossed transaction was associated with significantly less psychological impact than a parallel transaction for the 'Grim Reaper' advertisement. A similar trend was apparent for the 'Multiple Beds' advertisement. Important issues which warrant further research in order to evaluate whether transactional analysis could be a useful tool in promoting health are discussed.

  14. A Self-Instructional Course in Student Financial Aid Administration. Module 8: Need Analysis. Second Edition.

    ERIC Educational Resources Information Center

    Washington Consulting Group, Inc., Washington, DC.

    The eighth module in a 17-module self-instructional program on student financial aid administration (designed for novice student financial aid administrators and other personnel) focuses on need analysis. It provides an introduction to the management of federal financial aid programs authorized by the Higher Education Act Title IV. After…

  15. Failure Rate Data Analysis for High Technology Components

    SciTech Connect

    L. C. Cadwallader

    2007-07-01

    Understanding component reliability helps designers create more robust future designs and supports efficient and cost-effective operations of existing machines. The accelerator community can leverage the commonality of its high-vacuum and high-power systems with those of the magnetic fusion community to gain access to a larger database of reliability data. Reliability studies performed under the auspices of the International Energy Agency are the result of an international working group, which has generated a component failure rate database for fusion experiment components. The initial database work harvested published data and now analyzes operating experience data. This paper discusses the usefulness of reliability data, describes the failure rate data collection and analysis effort, discusses reliability for components with scarce data, and points out some of the intersections between magnetic fusion experiments and accelerators.

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  17. Uncertainty Analysis via Failure Domain Characterization: Unrestricted Requirement Functions

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.; Giesy, Daniel P.

    2011-01-01

    This paper proposes an uncertainty analysis framework based on the characterization of the uncertain parameter space. This characterization enables the identification of worst-case uncertainty combinations and the approximation of the failure and safe domains with a high level of accuracy. Because these approximations are comprised of subsets of readily computable probability, they enable the calculation of arbitrarily tight upper and lower bounds to the failure probability. The methods developed herein, which are based on nonlinear constrained optimization, are applicable to requirement functions whose functional dependency on the uncertainty is arbitrary and whose explicit form may even be unknown. Some of the most prominent features of the methodology are the substantial desensitization of the calculations from the assumed uncertainty model (i.e., the probability distribution describing the uncertainty) as well as the accommodation for changes in such a model with a practically insignificant amount of computational effort.

  18. NALDA (Naval Aviation Logistics Data Analysis) CAI (computer aided instruction)

    SciTech Connect

    Handler, B.H. ); France, P.A.; Frey, S.C.; Gaubas, N.F.; Hyland, K.J.; Lindsey, A.M.; Manley, D.O. ); Hunnum, W.H. ); Smith, D.L. )

    1990-07-01

    Data Systems Engineering Organization (DSEO) personnel developed a prototype computer aided instruction CAI system for the Naval Aviation Logistics Data Analysis (NALDA) system. The objective of this project was to provide a CAI prototype that could be used as an enhancement to existing NALDA training. The CAI prototype project was performed in phases. The task undertaken in Phase I was to analyze the problem and the alternative solutions and to develop a set of recommendations on how best to proceed. The findings from Phase I are documented in Recommended CAI Approach for the NALDA System (Duncan et al., 1987). In Phase II, a structured design and specifications were developed, and a prototype CAI system was created. A report, NALDA CAI Prototype: Phase II Final Report, was written to record the findings and results of Phase II. NALDA CAI: Recommendations for an Advanced Instructional Model, is comprised of related papers encompassing research on computer aided instruction CAI, newly developing training technologies, instructional systems development, and an Advanced Instructional Model. These topics were selected because of their relevancy to the CAI needs of NALDA. These papers provide general background information on various aspects of CAI and give a broad overview of new technologies and their impact on the future design and development of training programs. The paper within have been index separately elsewhere.

  19. Sound Classification in Hearing Aids Inspired by Auditory Scene Analysis

    NASA Astrophysics Data System (ADS)

    Büchler, Michael; Allegro, Silvia; Launer, Stefan; Dillier, Norbert

    2005-12-01

    A sound classification system for the automatic recognition of the acoustic environment in a hearing aid is discussed. The system distinguishes the four sound classes "clean speech," "speech in noise," "noise," and "music." A number of features that are inspired by auditory scene analysis are extracted from the sound signal. These features describe amplitude modulations, spectral profile, harmonicity, amplitude onsets, and rhythm. They are evaluated together with different pattern classifiers. Simple classifiers, such as rule-based and minimum-distance classifiers, are compared with more complex approaches, such as Bayes classifier, neural network, and hidden Markov model. Sounds from a large database are employed for both training and testing of the system. The achieved recognition rates are very high except for the class "speech in noise." Problems arise in the classification of compressed pop music, strongly reverberated speech, and tonal or fluctuating noises.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaonan; He, Yingjie; Li, Jinping

    2016-10-01

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

  1. The Worker Exposure Failure Modes and Effects Analysis

    SciTech Connect

    Cadwallader, L.C.

    2005-05-15

    The Worker Exposure Failure Modes and Effects Analysis (WE-FMEA) is a new approach to quantitatively evaluate worker risks from possible failures of co-located equipment in the complex environment of a magnetic or inertial fusion experiment. For next-step experiments such as the International Thermonuclear Experimental Reactor (ITER) or the National Ignition Facility (NIF), the systems and equipment will be larger, handle more throughput or power, and will, in general, be more robust than past experiments. These systems and equipment are necessary to operate the machine, but the rooms are congested with equipment, piping, and cables, which poses a new level of hazard for workers who will perform hands-on maintenance. The WE-FMEA systematically analyzes the nearby equipment and the work environment for equipment failure or inherent hazards, and then develops exposure scenarios. Once identified, the exposure scenarios are evaluated for the worker hazards and quantitative worker risk is calculated. Then risk scenarios are quantitatively compared to existing statistical data on worker injuries; high-risk scenarios can be identified and addressed in more detail to determine the proper means to reduce, mitigate, or protect against the hazard. The WE-FMEA approach is described and a cooling system maintenance example is given.

  2. Computer aided analysis, simulation and optimisation of thermal sterilisation processes.

    PubMed

    Narayanan, C M; Banerjee, Arindam

    2013-04-01

    Although thermal sterilisation is a widely employed industrial process, little work is reported in the available literature including patents on the mathematical analysis and simulation of these processes. In the present work, software packages have been developed for computer aided optimum design of thermal sterilisation processes. Systems involving steam sparging, jacketed heating/cooling, helical coils submerged in agitated vessels and systems that employ external heat exchangers (double pipe, shell and tube and plate exchangers) have been considered. Both batch and continuous operations have been analysed and simulated. The dependence of del factor on system / operating parameters such as mass or volume of substrate to be sterilised per batch, speed of agitation, helix diameter, substrate to steam ratio, rate of substrate circulation through heat exchanger and that through holding tube have been analysed separately for each mode of sterilisation. Axial dispersion in the holding tube has also been adequately accounted for through an appropriately defined axial dispersion coefficient. The effect of exchanger characteristics/specifications on the system performance has also been analysed. The multiparameter computer aided design (CAD) software packages prepared are thus highly versatile in nature and they permit to make the most optimum choice of operating variables for the processes selected. The computed results have been compared with extensive data collected from a number of industries (distilleries, food processing and pharmaceutical industries) and pilot plants and satisfactory agreement has been observed between the two, thereby ascertaining the accuracy of the CAD softwares developed. No simplifying assumptions have been made during the analysis and the design of associated heating / cooling equipment has been performed utilising the most updated design correlations and computer softwares.

  3. The future of computer-aided sperm analysis

    PubMed Central

    Mortimer, Sharon T; van der Horst, Gerhard; Mortimer, David

    2015-01-01

    Computer-aided sperm analysis (CASA) technology was developed in the late 1980s for analyzing sperm movement characteristics or kinematics and has been highly successful in enabling this field of research. CASA has also been used with great success for measuring semen characteristics such as sperm concentration and proportions of progressive motility in many animal species, including wide application in domesticated animal production laboratories and reproductive toxicology. However, attempts to use CASA for human clinical semen analysis have largely met with poor success due to the inherent difficulties presented by many human semen samples caused by sperm clumping and heavy background debris that, until now, have precluded accurate digital image analysis. The authors review the improved capabilities of two modern CASA platforms (Hamilton Thorne CASA-II and Microptic SCA6) and consider their current and future applications with particular reference to directing our focus towards using this technology to assess functional rather than simple descriptive characteristics of spermatozoa. Specific requirements for validating CASA technology as a semi-automated system for human semen analysis are also provided, with particular reference to the accuracy and uncertainty of measurement expected of a robust medical laboratory test for implementation in clinical laboratories operating according to modern accreditation standards. PMID:25926614

  4. Lithographic chip identification: meeting the failure analysis challenge

    NASA Astrophysics Data System (ADS)

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

    1992-06-01

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

  5. Failure and Reliability Analysis for the Master Pump Shutdown System

    SciTech Connect

    BEVINS, R.R.

    2000-09-05

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

  6. Meshfree analysis with the aid of NURBS boundary

    NASA Astrophysics Data System (ADS)

    Chi, Sheng-Wei; Lin, Shih-Po

    2016-09-01

    We present a meshfree analysis framework to integrate the geometric exactness of non-uniform rational B-splines (NURBS)-based isogeometric analysis (IGA) (Hughes et al., Comput Methods Appl Mech Eng 194:4135-4195, 2005) with the flexibility of meshfree approximations. In the framework, only the NURBS boundary surface immediately available from CAD tools is used to describe the exact problem domain, and meshfree particles are inserted inside the boundary surface, in a flexible manner, for construction of the approximation for analysis. Nitche's method is employed for imposing essential boundary conditions and the domain integration in the Galerkin formulation is performed based on variationally consistent integration (VCI) to recover integration exactness. The NURBS boundary surface from CAD serves as an aid in selecting particle distributions and as the integration net for the boundary integration required both for the Nitche's method and the VCI. As shown in numerical studies, the VCI is essential for the solution accuracy of the method. Several benchmarks are tested to examine the effectiveness of the proposed framework and numerical results are compared with those obtained by the IGA.

  7. Post Buckling Progressive Failure Analysis of Composite Laminated Stiffened Panels

    NASA Astrophysics Data System (ADS)

    Anyfantis, Konstantinos N.; Tsouvalis, Nicholas G.

    2012-06-01

    The present work deals with the numerical prediction of the post buckling progressive and final failure response of stiffened composite panels based on structural nonlinear finite element methods. For this purpose, a progressive failure model (PFM) is developed and applied to predict the behaviour of an experimentally tested blade-stiffened panel found in the literature. Failure initiation and propagation is calculated, owing to the accumulation of the intralaminar failure modes induced in fibre reinforced composite materials. Hashin failure criteria have been employed in order to address the fiber and matrix failure modes in compression and tension. On the other hand, the Tsai-Wu failure criterion has been utilized for addressing shear failure. Failure detection is followed with the introduction of corresponding material degradation rules depending on the individual failure mechanisms. Failure initiation and failure propagation as well as the post buckling ultimate attained load have been numerically evaluated. Final failure behaviour of the simulated stiffened panel is due to sudden global failure, as concluded from comparisons between numerical and experimental results being in good agreement.

  8. Failure Analysis of Nonvolatile Residue (NVR) Analyzer Model SP-1000

    NASA Technical Reports Server (NTRS)

    Potter, Joseph C.

    2011-01-01

    National Aeronautics and Space Administration (NASA) subcontractor Wiltech contacted the NASA Electrical Lab (NE-L) and requested a failure analysis of a Solvent Purity Meter; model SP-IOOO produced by the VerTis Instrument Company. The meter, used to measure the contaminate in a solvent to determine the relative contamination on spacecraft flight hardware and ground servicing equipment, had been inoperable and in storage for an unknown amount of time. NE-L was asked to troubleshoot the unit and make a determination on what may be required to make the unit operational. Through the use of general troubleshooting processes and the review of a unit in service at the time of analysis, the unit was found to be repairable but would need the replacement of multiple components.

  9. Functional Analysis of HIV/AIDS Stigma: Consensus or Divergence?

    ERIC Educational Resources Information Center

    Hosseinzadeh, Hassan; Hossain, Syeda Zakia

    2011-01-01

    Functional theory proposes that attitudes may serve a variety of purposes for individuals. This study aimed to determine whether stigmatized attitudes toward HIV/AIDS serve the same function for all (consensus function) or serve different functions for different individuals (divergence function) by assessing various aspects of HIV/AIDS stigma…

  10. HIV/AIDS in Communities of Color: A Lasswellian Analysis

    ERIC Educational Resources Information Center

    Humble Michael N.; Bride, Brian E.

    2009-01-01

    HIV/AIDS has changed drastically since the introduction of life-saving drugs known as highly active antiretroviral treatment. These same drugs have created a schism between the haves and the have-nots in society. The demographics of the disease have also changed alongside treatment. This article explores the changing face of HIV/AIDS in the 21st…

  11. 75 FR 53968 - Reverb Communications, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-02

    ... proposed order. This matter involves the public relations, marketing, and sales services that respondents... Reverb Communications, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal... methods of competition. The attached Analysis to Aid Public Comment describes both the allegations in...

  12. Development in Wear Debris Morphological Analysis at RAF Early Failure Detection Centres

    DTIC Science & Technology

    1996-04-01

    previous program, CASPA (Computer-Aided Systematic Particle Analysis) which was established to assist in the analysis of wear debris extracted from oil...Luxmoore; ’The development of a computer- aided systematic particle analysis procedure - CASPA " Lubr. Eng., 48, 12 (1992), 940- 946. 7. Roylance, I.A

  13. Spatial Stratification of Order As Used in Failure Analysis

    NASA Astrophysics Data System (ADS)

    Leonard, Robert H.; Bachlechner, Martina E.

    2007-03-01

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

  14. Nonlinear Temperature Dependent Failure Analysis of Finite Width Composite Laminates.

    DTIC Science & Technology

    1979-12-01

    tangent modulii obtained by Ramberg-Osgood parameters. It is shown that a’ring stresses and stresses due to tensile loading are significant as edge ... effect in all types of laminate studies. The tensor polynomial failure criterion is used to predict the initiation of failure. The mode of failure is

  15. Ayame/PAM-D apogee kick motor nozzle failure analysis

    NASA Technical Reports Server (NTRS)

    1981-01-01

    The failure of two communication satellites during firing sequence were examined. The correlation/comparison of the circumstances of the Ayame incidents and the failure of the STAR 48 (DM-2) motor are reviewed. The massive nozzle failure of the AKM to determine the impact on spacecraft performance is examined. It is recommended that a closer watch is kept on systems techniques,

  16. Methodology for Benefit Analysis of CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) in USN Shipyards.

    DTIC Science & Technology

    1984-03-01

    D-Ri38 398 METHODOLOGY FOR BENEFIT ANALYSIS OF CAD/CAM / (COMPUTER-HIDED DESIGN/COMPUTER-AIDED MANUFACTURING) IN USN SHIPYARDS(U) NAVAL POSTGRADUATE...Monterey, California DT I ~" t • EB3 1984 THESIS METHODOLOGY FOR BENEFIT ANALYSIS OF CAD/CAM IN USN SHIPYARDS by Richard B. Grahlman March 1984 Thesis...REPORT & PERIOD COVERED Methodology for Benefit Analysis of CAD/CAM Mastrch 1984 i in UM Sipyads. PERFORMIANG ORG. REPORT NUM8ER 7- AUHOW11111 4

  17. Comprehensive failure analysis of leakage faults in bipolar transistors

    NASA Astrophysics Data System (ADS)

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

    2004-02-01

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

  18. Micromechanical analysis of the failure process in ceramic matrix composites

    NASA Technical Reports Server (NTRS)

    Rubinstein, Asher A.

    1991-01-01

    An analysis of the effectiveness of fiber reinforcement in brittle matrix composites is presented. The analytical method allows consideration of discrete fiber distribution and examination of the development of crack growth parameters on the microscale. The problem associated with bridging zone development is addressed here; therefore, the bridging zone is considered to be smaller than the main preexisting crack, and the small scale approach is used. The mechanics of the reinforcement is accurately accounted for in the process zone of a growing crack. Closed form solutions characterizing the initial failure process are presented for linear and nonlinear force-fiber pullout displacement relationships. The implicit exact solution for the extended bridging zone is presented as well.

  19. Magellan/Galileo solder joint failure analysis and recommendations

    NASA Technical Reports Server (NTRS)

    Ross, Ronald G., Jr.

    1989-01-01

    On or about November 10, 1988 an open circuit solder joint was discovered in the Magellan Radar digital unit (DFU) during integration testing at Kennedy Space Center (KSC). A detailed analysis of the cause of the failure was conducted at the Jet Propulsion Laboratory leading to the successful repair of many pieces of affected electronic hardware on both the Magellan and Galileo spacecraft. The problem was caused by the presence of high thermal coefficient of expansion heat sink and conformal coating materials located in the large (0.055 inch) gap between Dual Inline Packages (DIPS) and the printed wiring board. The details of the observed problems are described and recommendations are made for improved design and testing activities in the future.

  20. Computer-aided pulmonary image analysis in small animal models

    PubMed Central

    Xu, Ziyue; Bagci, Ulas; Mansoor, Awais; Kramer-Marek, Gabriela; Luna, Brian; Kubler, Andre; Dey, Bappaditya; Foster, Brent; Papadakis, Georgios Z.; Camp, Jeremy V.; Jonsson, Colleen B.; Bishai, William R.; Jain, Sanjay; Udupa, Jayaram K.; Mollura, Daniel J.

    2015-01-01

    Purpose: To develop an automated pulmonary image analysis framework for infectious lung diseases in small animal models. Methods: The authors describe a novel pathological lung and airway segmentation method for small animals. The proposed framework includes identification of abnormal imaging patterns pertaining to infectious lung diseases. First, the authors’ system estimates an expected lung volume by utilizing a regression function between total lung capacity and approximated rib cage volume. A significant difference between the expected lung volume and the initial lung segmentation indicates the presence of severe pathology, and invokes a machine learning based abnormal imaging pattern detection system next. The final stage of the proposed framework is the automatic extraction of airway tree for which new affinity relationships within the fuzzy connectedness image segmentation framework are proposed by combining Hessian and gray-scale morphological reconstruction filters. Results: 133 CT scans were collected from four different studies encompassing a wide spectrum of pulmonary abnormalities pertaining to two commonly used small animal models (ferret and rabbit). Sensitivity and specificity were greater than 90% for pathological lung segmentation (average dice similarity coefficient > 0.9). While qualitative visual assessments of airway tree extraction were performed by the participating expert radiologists, for quantitative evaluation the authors validated the proposed airway extraction method by using publicly available EXACT’09 data set. Conclusions: The authors developed a comprehensive computer-aided pulmonary image analysis framework for preclinical research applications. The proposed framework consists of automatic pathological lung segmentation and accurate airway tree extraction. The framework has high sensitivity and specificity; therefore, it can contribute advances in preclinical research in pulmonary diseases. PMID:26133591

  1. Computer-aided pulmonary image analysis in small animal models

    SciTech Connect

    Xu, Ziyue; Mansoor, Awais; Mollura, Daniel J.; Bagci, Ulas; Kramer-Marek, Gabriela; Luna, Brian; Kubler, Andre; Dey, Bappaditya; Jain, Sanjay; Foster, Brent; Papadakis, Georgios Z.; Camp, Jeremy V.; Jonsson, Colleen B.; Bishai, William R.; Udupa, Jayaram K.

    2015-07-15

    Purpose: To develop an automated pulmonary image analysis framework for infectious lung diseases in small animal models. Methods: The authors describe a novel pathological lung and airway segmentation method for small animals. The proposed framework includes identification of abnormal imaging patterns pertaining to infectious lung diseases. First, the authors’ system estimates an expected lung volume by utilizing a regression function between total lung capacity and approximated rib cage volume. A significant difference between the expected lung volume and the initial lung segmentation indicates the presence of severe pathology, and invokes a machine learning based abnormal imaging pattern detection system next. The final stage of the proposed framework is the automatic extraction of airway tree for which new affinity relationships within the fuzzy connectedness image segmentation framework are proposed by combining Hessian and gray-scale morphological reconstruction filters. Results: 133 CT scans were collected from four different studies encompassing a wide spectrum of pulmonary abnormalities pertaining to two commonly used small animal models (ferret and rabbit). Sensitivity and specificity were greater than 90% for pathological lung segmentation (average dice similarity coefficient > 0.9). While qualitative visual assessments of airway tree extraction were performed by the participating expert radiologists, for quantitative evaluation the authors validated the proposed airway extraction method by using publicly available EXACT’09 data set. Conclusions: The authors developed a comprehensive computer-aided pulmonary image analysis framework for preclinical research applications. The proposed framework consists of automatic pathological lung segmentation and accurate airway tree extraction. The framework has high sensitivity and specificity; therefore, it can contribute advances in preclinical research in pulmonary diseases.

  2. The response of the Italian press to AIDS: a 22-month analysis.

    PubMed

    Aloisi; Girardi, E; Ippolito, G

    2001-01-01

    This study analyses the way in which the Italian press reported Acquired Immunodeficiency Syndrome (AIDS) over a 22-month period from September 1993 to June 1995, when no national AIDS information campaigns were made in Italy. During this period we collected, read, and categorized every article relating to Human Immunodeficiency Virus (HIV) and AIDS in fourteen newspapers and two news magazines with the highest national circulation. Articles were then assigned to one of six content categories: statistics, basic science, cure and vaccine, education/awareness and prevention issue, government or non-goverment organizations response, and people with AIDS (PWA) personal portrayals. A total of 4,228 articles referring to HIV/AIDS were identified. Analysis of the featured topics reveals several clear differences in the coverage of aspects of AIDS. The major category was represented by government or non-goverment organization response which accounted for 1,341 articles. Overall, this analysis suggests that, even long after the beginning of the epidemic, the press continues to see AIDS as an important issue. However, the articles explaining scientifically the AIDS epidemic were very few. The majority of AIDS-related information was spread in consequence of sensational events. Further analysis of PWA coverage shows that most articles discussed news that could provoke a negative feeling towards HIV-infected patients among the general population.

  3. Space Shuttle Stiffener Ring Foam Failure Analysis, a Non-Conventional Approach

    NASA Technical Reports Server (NTRS)

    Howard, Philip M.

    2015-01-01

    The Space Shuttle Program made use of the excellent properties of rigid polyurethane foam for cryogenic tank insulation and as structural protection on the solid rocket boosters. When foam applications de-bond, classical methods of failure analysis did not provide root cause of the failure of the foam. Realizing that foam is the ideal media to document and preserve its own mode of failure, thin sectioning was seen as a logical approach for foam failure analysis to observe the three dimensional morphology of the foam cells. The cell foam morphology provided a much greater understanding of the failure modes than previously achieved.

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

    NASA Technical Reports Server (NTRS)

    Russell, Richard W.

    2010-01-01

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

  5. Failure Analysis in Space: International Space Station (ISS) Starboard Solar Alpha Rotary Joint (SARJ) Debris Analysis

    NASA Technical Reports Server (NTRS)

    Long, V. S.; Wright, M. C.; McDanels, S. J.; Lubas, D.; Tucker, B.; Marciniak, P. J.

    2010-01-01

    This slide presentation reviews the debris analysis of the Starboard Solar Alpha Rotary Joint (SARJ), a mechanism that is designed to keep the solar arrays facing the sun. The goal of this was to identify the failure mechanism based on surface morphology and to determine the source of debris through elemental and particle analysis.

  6. The Work of Teacher Aides in Australia: An Analysis of Job Advertisements

    ERIC Educational Resources Information Center

    Stephenson, Jennifer; Carter, Mark

    2014-01-01

    Although teacher aides are often employed in schools to provide support for students with disabilities and special education needs, there is limited Australian research on their work and employer expectations. This article provides an analysis of advertisements for teacher aide positions, and compares the content of advertisements with role…

  7. Failure analysis of a tool steel torque shaft

    NASA Technical Reports Server (NTRS)

    Reagan, J. R.

    1981-01-01

    A low design load drive shaft used to deliver power from an experimental exhaust heat recovery system to the crankshaft of an experimental diesel truck engine failed during highway testing. An independent testing laboratory analyzed the failure by routine metallography and attributed the failure to fatigue induced by a banded microstructure. Visual examination by NASA of the failed shaft plus the knowledge of the torsional load that it carried pointed to a 100 percent ductile failure with no evidence of fatigue. Scanning electron microscopy confirmed this. Torsional test specimens were produced from pieces of the failed shaft and torsional overload testing produced identical failures to that which had occurred in the truck engine. This pointed to a failure caused by a high overload and although the microstructure was defective it was not the cause of the failure.

  8. Incorporation of a progressive failure analysis method in the CSM testbed software system

    NASA Technical Reports Server (NTRS)

    Arenburg, Robert T.

    1989-01-01

    Analysis of the postbuckling behavior of composite shell structures pose many difficult and challenging problems in the field of structural mechanics. Current analysis methods perform well for most cases in predicting the postbuckling response of undamaged components. To predict component behavior accurately at higher load levels, the analysis must include the effects of local material failures. The CSM testbed software system is a highly modular structural analysis system currently under development at Langley Research Center. One of the primary goals of the CSM testbed is to provide a software environment for the development of advanced structural analysis methods and modern numerical methods which will exploit advanced computer architecture such as parallel-vector processors. Development of a progressive failure analysis method consists of the design and implementation of a processor which will perform the ply-level progressive failure analysis and the development of a geometrically nonlinear analysis procedure which incorporates the progressive failure processor. Regarding the development of the progressive failure processor, two components are required: failure criteria and a degradation model. For the initial implementation, the failure criteria of Hashin will be used. For a matrix failure which typically indicates the development of transverse matrix cracks, the ply properties will be degraded. Work to date includes the design of the progressive failure analysis processor and initial plans for the controlling geometrically nonlinear analysis procedure. The implementation of the progressive failure analysis has begun. Access to the model database and the Hashin failure criteria are completed. Work is in progress on the input/output operations for the processor related data and the finite element model updating procedures. In total the progressive failure processor is approximately one-third complete.

  9. Physicochemical characterization and failure analysis of military coating systems

    NASA Astrophysics Data System (ADS)

    Keene, Lionel Thomas

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

  10. Common-Cause Failure Analysis in Event Assessment

    SciTech Connect

    D. M. Rasmuson; D. L. Kelly

    2008-06-01

    This paper reviews the basic concepts of modelling common-cause failures (CCFs) in reliability and risk studies and then applies these concepts to the treatment of CCF in event assessment. The cases of a failed component (with and without shared CCF potential) and a component being unavailable due to preventive maintenance or testing are addressed. The treatment of two related failure modes (e.g. failure to start and failure to run) is a new feature of this paper, as is the treatment of asymmetry within a common-cause component group.

  11. Assessing the Value-Added by the Environmental Testing Process with the Aide of Physics/Engineering of Failure Evaluations

    NASA Technical Reports Server (NTRS)

    Cornford, S.; Gibbel, M.

    1997-01-01

    NASA's Code QT Test Effectiveness Program is funding a series of applied research activities focused on utilizing the principles of physics and engineering of failure and those of engineering economics to assess and improve the value-added by the various validation and verification activities to organizations.

  12. Probabilistic Failure Analysis for Wound Composite Ceramic Cladding Assembly

    SciTech Connect

    Hemrick, James Gordon; Lara-Curzio, Edgar

    2013-01-01

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

  13. FMEA, the alternative process hazard method. [Failure Mode Effects Analysis

    SciTech Connect

    Goyal, R.K. )

    1993-05-01

    Failure mode effects analysis (FMEA) is an old reliability/assurance tool finding its way into the HPI. Not popular yet, this hazard technique has some viable applications that can improve hazard assessment data. Notably, FMEA studies can identify possible areas for improvement that may have not been discovered using other methods. Also, FMEA is not as labor intensive and costly as other process hazard analysis (PHA) methods. PSHA 1910.119 set in place an informational structure whose main purpose is the reduction of potential accidents and minimizing risks in the event of an accident. Consequently, HPI operators must evaluate their process systems and identify potential major hazards, such as fires, explosions and accidental release of toxic/hazardous chemicals, and protect their facilities, employees, the public and the environment. But, which PHA method(s) apply to a particular plant or process still remains a difficult question. This paper describes what FMEA is; types of FMEA; how to conduct a FMEA study; comparison with HAZOP (hazard and operability study); computer software; applicability of FMEA; and examples of its use.

  14. Performance analysis of ten brands of batteries for hearing aids

    PubMed Central

    Penteado, Silvio Pires; Bento, Ricardo Ferreira

    2013-01-01

    Summary Introduction: Comparison of the performance of hearing instrument batteries from various manufacturers can enable otologists, audiologists, or final consumers to select the best products, maximizing the use of these materials. Aim: To analyze the performance of ten brands of batteries for hearing aids available in the Brazilian marketplace. Methods: Hearing aid batteries in four sizes were acquired from ten manufacturers and subjected to the same test conditions in an acoustic laboratory. Results: The results obtained in the laboratory contrasted with the values reported by manufacturers highlighted significant discrepancies, besides the fact that certain brands in certain sizes perform better on some tests, but does not indicate which brand is the best in all sizes. Conclusions: It was possible to investigate the performance of ten brands of hearing aid batteries and describe the procedures to be followed for leakage, accidental intake, and disposal. PMID:25992026

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

    PubMed

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

    2016-10-06

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

  16. Failure of highly active antiretroviral therapy in reconstituting immune response to Clostridium tetani vaccine in aged AIDS patients.

    PubMed

    Andrade, Regis M; Andrade, Arnaldo F B; Lazaro, Marta A; Vieira, Morgana M M; Barros, Priscila O; Borner, Alice R S; Silva-Filho, Renato G; Santos, Juliana O; Brindeiro, Rodrigo M; Tanuri, Amilcar; Bento, Cleonice A M

    2010-05-01

    The purpose of this study was to evaluate the impact of age on tetanus-specific immune response in successfully highly active antiretroviral therapy-treated AIDS patients, using healthy age-matched individuals as controls. Whole Peripheral blood mononuclear cells or CD8(+) cell-depleted peripheral blood mononuclear cells from previously tetanus toxoid (TT)-immunized individuals were activated with TT plus IL-2, and cell proliferation, cytokine production, and in vitro HIV-1 replication were measured. The in vivo magnitude of the humoral immune response was also assessed by antibody measurements. Our results showed that, compared with other groups, both in vitro TT-specific lymphoproliferation and serum antibody concentration were lower in older AIDS patients. Although the IL-1beta and tumour necrosis factor alpha (TNF-alpha) production were higher in cultures from aged HIV-1-infected patients, a dramatic damage on the interferon gamma (IFN-gamma) release was observed, when compared with younger patients. CD8(+) T lymphocytes depletion reduced IL-1beta and TNF-alpha release in the older groups, however, it did not significantly alter their IFN-gamma production. Furthermore, the neutralization of endogenous IL-10 did not change the IFN-gamma deficiency in older AIDS patients. Finally, the lower cellular immune response in this patient group was not related to in vitro HIV-1 replication. The results suggest that successfully highly active antiretroviral therapy-treated aged AIDS patients do not reconstitute the immune response to TT, making them probably more susceptible to tetanus even after vaccination.

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

    PubMed

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

    2014-04-01

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

  18. Progressive failure analysis of fibrous composite materials and structures

    NASA Technical Reports Server (NTRS)

    Bahei-El-din, Yehia A.

    1990-01-01

    A brief description is given of the modifications implemented in the PAFAC finite element program for the simulation of progressive failure in fibrous composite materials and structures. Details of the memory allocation, input data, and the new subroutines are given. Also, built-in failure criteria for homogeneous and fibrous composite materials are described.

  19. Letter report seismic shutdown system failure mode and effect analysis

    SciTech Connect

    KECK, R.D.

    1999-09-01

    The Supply Ventilation System Seismic Shutdown ensures that the 234-52 building supply fans, the dry air process fans and vertical development calciner are shutdown following a seismic event. This evaluates the failure modes and determines the effects of the failure modes.

  20. Analysis of the progressive failure of brittle matrix composites

    NASA Technical Reports Server (NTRS)

    Thomas, David J.

    1995-01-01

    This report investigates two of the most common modes of localized failures, namely, periodic fiber-bridged matrix cracks and transverse matrix cracks. A modification of Daniels' bundle theory is combined with Weibull's weakest link theory to model the statistical distribution of the periodic matrix cracking strength for an individual layer. Results of the model predictions are compared with experimental data from the open literature. Extensions to the model are made to account for possible imperfections within the layer (i.e., nonuniform fiber lengths, irregular crack spacing, and degraded in-situ fiber properties), and the results of these studies are presented. A generalized shear-lag analysis is derived which is capable of modeling the development of transverse matrix cracks in material systems having a general multilayer configuration and under states of full in-plane load. A method for computing the effective elastic properties for the damaged layer at the global level is detailed based upon the solution for the effects of the damage at the local level. This methodology is general in nature and is therefore also applicable to (0(sub m)/90(sub n))(sub s) systems. The characteristic stress-strain response for more general cases is shown to be qualitatively correct (experimental data is not available for a quantitative evaluation), and the damage evolution is recorded in terms of the matrix crack density as a function of the applied strain. Probabilistic effects are introduced to account for the statistical nature of the material strengths, thus allowing cumulative distribution curves for the probability of failure to be generated for each of the example laminates. Additionally, Oh and Finney's classic work on fracture location in brittle materials is extended and combined with the shear-lag analysis. The result is an analytical form for predicting the probability density function for the location of the next transverse crack occurrence within a crack bounded

  1. Demographic, etiological, and histological pulmonary analysis of patients with acute respiratory failure: a study of 19 years of autopsies

    PubMed Central

    de Matos Soeiro, Alexandre; Ruppert, Aline D; Canzian, Mauro; Parra, Edwin R; Farhat, Cecília; Capelozzi, Vera L

    2011-01-01

    INTRODUCTION: Acute respiratory failure has been one of the most important causes of death in intensive care units, and certain aspects of its pulmonary pathology are currently unknown. OBJECTIVES: The objective was to describe the demographic data, etiology, and pulmonary histopathological findings of different diseases in the autopsies of patients with acute respiratory failure. METHOD: Autopsies of 4,710 patients with acute respiratory failure from 1990 to 2008 were reviewed, and the following data were obtained: age, sex, and major associated diseases. The pulmonary histopathology was categorized as diffuse alveolar damage, pulmonary edema, alveolar hemorrhage, and lymphoplasmacytic interstitial pneumonia. The odds ratio of the concordance between the major associated diseases and specific autopsy findings was calculated using logistic regression. RESULTS: Bacterial bronchopneumonia was present in 33.9% of the cases and cancer in 28.1%. The pulmonary histopathology showed diffuse alveolar damage in 40.7% (1,917) of the cases. A multivariate analysis showed a significant and powerful association between diffuse alveolar damage and bronchopneumonia, HIV/AIDS, sepsis, and septic shock, between liver cirrhosis and pulmonary embolism, between pulmonary edema and acute myocardial infarction, between dilated cardiomyopathy and cancer, between alveolar hemorrhage and bronchopneumonia and pulmonary embolism, and between lymphoplasmacytic interstitial pneumonia and HIV/AIDS and liver cirrhosis. CONCLUSIONS: Bronchopneumonia was the most common diagnosis in these cases. The most prevalent pulmonary histopathological pattern was diffuse alveolar damage, which was associated with different inflammatory conditions. Further studies are necessary to elucidate the complete pathophysiological mechanisms involved with each disease and the development of acute respiratory failure. PMID:21876973

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  3. Spatial correlation analysis of cascading failures: Congestions and Blackouts

    PubMed Central

    Daqing, Li; Yinan, Jiang; Rui, Kang; Havlin, Shlomo

    2014-01-01

    Cascading failures have become major threats to network robustness due to their potential catastrophic consequences, where local perturbations can induce global propagation of failures. Unlike failures spreading via direct contacts due to structural interdependencies, overload failures usually propagate through collective interactions among system components. Despite the critical need in developing protection or mitigation strategies in networks such as power grids and transportation, the propagation behavior of cascading failures is essentially unknown. Here we find by analyzing our collected data that jams in city traffic and faults in power grid are spatially long-range correlated with correlations decaying slowly with distance. Moreover, we find in the daily traffic, that the correlation length increases dramatically and reaches maximum, when morning or evening rush hour is approaching. Our study can impact all efforts towards improving actively system resilience ranging from evaluation of design schemes, development of protection strategies to implementation of mitigation programs. PMID:24946927

  4. Spatial correlation analysis of cascading failures: Congestions and Blackouts

    NASA Astrophysics Data System (ADS)

    Daqing, Li; Yinan, Jiang; Rui, Kang; Havlin, Shlomo

    2014-06-01

    Cascading failures have become major threats to network robustness due to their potential catastrophic consequences, where local perturbations can induce global propagation of failures. Unlike failures spreading via direct contacts due to structural interdependencies, overload failures usually propagate through collective interactions among system components. Despite the critical need in developing protection or mitigation strategies in networks such as power grids and transportation, the propagation behavior of cascading failures is essentially unknown. Here we find by analyzing our collected data that jams in city traffic and faults in power grid are spatially long-range correlated with correlations decaying slowly with distance. Moreover, we find in the daily traffic, that the correlation length increases dramatically and reaches maximum, when morning or evening rush hour is approaching. Our study can impact all efforts towards improving actively system resilience ranging from evaluation of design schemes, development of protection strategies to implementation of mitigation programs.

  5. Spatial correlation analysis of cascading failures: congestions and blackouts.

    PubMed

    Daqing, Li; Yinan, Jiang; Rui, Kang; Havlin, Shlomo

    2014-06-20

    Cascading failures have become major threats to network robustness due to their potential catastrophic consequences, where local perturbations can induce global propagation of failures. Unlike failures spreading via direct contacts due to structural interdependencies, overload failures usually propagate through collective interactions among system components. Despite the critical need in developing protection or mitigation strategies in networks such as power grids and transportation, the propagation behavior of cascading failures is essentially unknown. Here we find by analyzing our collected data that jams in city traffic and faults in power grid are spatially long-range correlated with correlations decaying slowly with distance. Moreover, we find in the daily traffic, that the correlation length increases dramatically and reaches maximum, when morning or evening rush hour is approaching. Our study can impact all efforts towards improving actively system resilience ranging from evaluation of design schemes, development of protection strategies to implementation of mitigation programs.

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

    NASA Technical Reports Server (NTRS)

    Scott, John H.

    2009-01-01

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

  7. Urine monitoring system failure analysis and operational verification test report

    NASA Technical Reports Server (NTRS)

    Glanfield, E. J.

    1978-01-01

    Failure analysis and testing of a prototype urine monitoring system (UMS) are reported. System performance was characterized by a regression formula developed from volume measurement test data. When the volume measurement test data. When the volume measurement data was imputted to the formula, the standard error of the estimate calculated using the regression formula was found to be within 1.524% of the mean of the mass of the input. System repeatability was found to be somewhat dependent upon the residual volume of the system and the evaporation of fluid from the separator. The evaporation rate was determined to be approximately 1cc/minute. The residual volume in the UMS was determined by measuring the concentration of LiCl in the flush water. Observed results indicated residual levels in the range of 9-10ml, however, results obtained during the flushing efficiency test indicated a residual level of approximately 20ml. It is recommended that the phase separator pumpout time be extended or the design modified to minimize the residual level.

  8. Failure And Yield Analysis Techniques For Readout Devices Tested In A High Throughput Automated Wafer Probing Environment

    NASA Astrophysics Data System (ADS)

    Jolivet, Noel D.; Holoien, Lee D.

    1990-01-01

    Failure and yield analysis capabilities were developed for focal plane array (FPA) readout devices probe tested at wafer level instead of merely performing production rate testing and cataloging data. Innovative test strategies have been combined with software techniques to provide tools which accomplish these analyses while maintaining high throughput in test. This approach has been beneficial and valuable in saving test time when searching for hardware faults, investigating design susceptibilities, revealing foundry process variations from wafer to wafer and/or lot to lot, and creating a yield model for the parts tested. Testing of readout devices has historically been viewed as a major obstacle in high volume production of reliable components for focal plane systems. Thorough testing in a high throughput automated wafer probe environment may be achieved, but often at the expense of real-time analysis of failures and yield factors. Production testing has been established with these goals in mind rather than as an afterthought. This enables one to identify failure mechanisms as they occur in order to reduce yield loss and unnecessary test time. In addition to performing requisite data base management, routines have been created to re-sort data and reevaluate yield through varying performance parameter limits, to track and map failure mechanisms as they are encountered, to examine acquired data as a function of limits, and to provide yield information for feedback response to foundry processing. Ideas for aiding operators in recognizing and diagnosing possible test set hardware problems (as opposed to on-chip failures) have also been implemented.

  9. Using Dynamic Master Logic Diagram for component partial failure analysis

    SciTech Connect

    Ni, T.; Modarres, M.

    1996-12-01

    A methodology using the Dynamic Master Logic Diagram (DMLD) for the evaluation of component partial failure is presented. Since past PRAs have not focused on partial failure effects, the reliability of components are only based on the binary state assumption, i.e. defining a component as fully failed or functioning. This paper is to develop an approach to predict and estimate the component partial failure on the basis of the fuzzy state assumption. One example of the application of this methodology with the reliability function diagram of a centrifugal pump is presented.

  10. Probabilistic analysis of cascade failure dynamics in complex network

    NASA Astrophysics Data System (ADS)

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

    2016-11-01

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

  11. Failure Analysis of Discrete Damaged Tailored Extension-Shear-Coupled Stiffened Composite Panels

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.

    2005-01-01

    The results of an analytical and experimental investigation of the failure of composite is tiffener panels with extension-shear coupling are presented. This tailored concept, when used in the cover skins of a tiltrotor aircraft wing has the potential for increasing the aeroelastic stability margins and improving the aircraft productivity. The extension-shear coupling is achieved by using unbalanced 45 plies in the skin. The failure analysis of two tailored panel configurations that have the center stringer and adjacent skin severed is presented. Finite element analysis of the damaged panels was conducted using STAGS (STructural Analysis of General Shells) general purpose finite element program that includes a progressive failure capability for laminated composite structures that is based on point-stress analysis, traditional failure criteria, and ply discounting for material degradation. The progressive failure predicted the path of the failure and maximum load capability. There is less than 12 percent difference between the predicted failure load and experimental failure load. There is a good match of the panel stiffness and strength between the progressive failure analysis and the experimental results. The results indicate that the tailored concept would be feasible to use in the wing skin of a tiltrotor aircraft.

  12. Precision analysis of passive BD aided pseudolites positioning system

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoming; Zhao, Yan

    2007-11-01

    In recent years BD (BeiDou positioning system), an active satellite navigation system, has been widely applied in geodetic survey, precise engineering survey and GNC (guide, navigation and control system) of weapons because of its reliability and availability. However, it has several problems on the accuracy, anti-interference and active-positioning. A passive BD aided pseudolites positioning system is introduced in details in this paper. The configuration and the operating principle of system are presented. In analyzing the precision of location, one of the crucial aspects to be studied is how to determine the arrangement of the pseudolites to get the good GDOP, which is discussed in the different arrangements of the pseudolites in this paper. The simulation results show that the VDOP (vertical dilution of precision) of BD is improved due to introducing the pseudolites. The experiments indicate the validity of the methods and the improvement of the positioning precision in the BD aided pseudolite system.

  13. The construction of HIV/AIDS in Indian newspapers: a frame analysis.

    PubMed

    de Souza, Rebecca

    2007-01-01

    India has the largest number of people living with HIV/AIDS in Asia and the second largest in the world after South Africa (UNAIDS, 2004). The Indian media play an important role in the social construction of the HIV/AIDS problem nationally. This article uses grounded theory and the concept of media framing to understand the manner in which Indian newspapers make sense of the HIV/ AIDS problem. Specifically, this analysis focuses on the multiple and often times competing frames and resources used by stakeholders with respect the following topical categories (a) severity of HIV/AIDS in India, (b) causes and solutions, and (c) beliefs about who is at risk. The discussion elaborates on the tensions that emerge within the discursive space with respect to the HIV/AIDS frames.

  14. The Reconstruction and Failure Analysis of the Space Shuttle Columbia

    NASA Technical Reports Server (NTRS)

    Russell, Richard; Mayeaux, Brian; McDanels, Steven; Piascik, Robert; Sjaj. Samdee[; Jerman, Greg; Collins, Thomas; Woodworth, Warren

    2009-01-01

    (3200 F), which would severely degrade support structure, tiles, and RCC panel materials. The integrated failure analysis of wing leading edge debris and deposits strongly supported the hypothesis that a breach occurred at LH RCC Panel 8.

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

    NASA Astrophysics Data System (ADS)

    Corn, Aimee

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

  16. [Industrial first aid equipment: a historical analysis (1840-1914) ].

    PubMed

    Porro, Alessandro; Franchini, Antonia Francesca; Lorusso, Lorenzo; Falconi, Bruno

    2015-01-09

    Even if references to the tools required to intervene after an accident can be found in the works of Bernardino Ramazzini (1633-1714) or Johann Peter Frank (1745-1821), it was only with the development of industrial manufacturing that the need to study means to prevent and intervene in cases of accident became evident. In October 1894 the III Congrés International des Accidents du Travail et des Assurances Sociales was held in Milan. The following year, the Milanese trade union movement acknowledged the necessity to address the problem of industrial accidents. In 1896 the Association for Medical Assistance in  Industrial Accidents was founded in Milan. A specific medical institute was set up, appropriate first aid tools were collected and first aid rooms in the main Milanese factories were inaugurated. Nevertheless, few data seem to be available regarding the manufacture and use of this equipment in industry. We analyzed more than fifty catalogs of European industrial products, between 1843 and 1914, to study the evolution of first aid equipment for industrial use. They reflect and attest to the evolution of medicine and surgery, although some models seem to be related to certain industrial categories (railways, electrical appliances), some were similar to ordinary first aid boxes, others were strictly related to surgery; some could only be used by physicians, and others only by workers. Identification, conservation, and reappraisal of these tools is essential for historians of occupational health because these objects were normally not preserved. The catalogues of industrial production are also precious sources, since they are rarely preserved in public libraries and deserve to be used for historical studies.

  17. Analysis of Interval Changes on Mammograms for Computer Aided Diagnosis

    DTIC Science & Technology

    2000-05-01

    research groups are in the process of developing computer-aided diagnosis (CAD) methods which can provide a second opinion to the radiologist for the...benign lesions. 3- 8 Knowledge from di- features between current and previous mammograms of the verse areas such as signal and image processing , pattern...December 1999 2673 Sanjay-Gopal et al: A regional registration technique 26732673-p i n- iimages . The 74 temporal image pairs were comprised of 43 Cj

  18. Failure analysis of plasma-sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Berndt, C. C.; Miller, R. A.

    1984-01-01

    Thermally induced failure processes of plasma-sprayed thermal barrier coatings are examined. Cracking processes give rise to noise which was monitored by acoustic emission (AE) techniques. The sequential failure of coatings was examined from samples which were thermally cycled. Coatings of yttria-stabilized zirconia with and without a NiCrAlZr bond coat were plasma-sprayed onto U700 alloy rod. In some cases the substrate was intentionally overheated during deposition of the thermal protection system to check how this process variable influenced the AE response of the specimen. In this way a qualitative appraisal of how process variables affect coating integrity could be discerned in terms of cracking behavior. Results from up to seven consecutive thermal cycles are reported here. Coating failure was observed in all cases. Failure of the thermal protection system is progressive, since cracking and crack growth were observed prior to ultimate failure. Thus castastrophic failure occurs at some stage when there is a transformation from the microcrack to a macrocrack network.

  19. Clinico-Epidemiological Analysis of HIV/AIDS Patients

    PubMed Central

    Ertunc, Baris; Kaya, Selcuk; Koksal, Iftihar

    2016-01-01

    Objective: The aim of this study was to examine clinico-epidemiological properties of HIV/AIDS patients. Materials and Methods: For this purpose, 115 HIV/AIDS patients monitored in our clinic between January 1, 1998, and December 31, 2013, were retrospectively evaluated. Results: For the 115 patients with a diagnosis of HIV/AIDS that we monitored, the mean age at the time of presentation was 34.5±13.21 (10–79) years. Eighty-nine (76.5%) patients were male and 27 (23.5%), female. In this study, HIV/AIDS was the most prevalent in the young male population with a low educational and sociocultural level. The most common mode of transmission in our patients was heterosexual relations: approximately 1 patient in 3 had a history of traveling to countries with a high prevalence of HIV/AIDS, namely, Russia and Ukraine. The examination of diagnosis with respect to years showed an increase in new cases since 2008. Only 21 (18.3%) of our patients were diagnosed through clinical symptoms, while 91 (81.7%) during routine scanning. At first presentation, 68% of our patients were stage A; 4.7%, stage B; and 27.3%, stage C. The mean length of the monitoring of our patients was 2.74 years (2–180 months). Thirteen (11.3%) patients died due to opportunistic infections and malignities. The most common opportunistic infection was tuberculosis (16.5%), followed by syphilis and HBV. Malignity, most commonly intracranial tumor, was seen in 8.6% patients. Conclusion: The disease was generally seen in the young male population with a low sociocultural level, and it was most frequently transmitted by heterosexual sexual contact. This clearly shows the importance of sufficient, accurate information, and education on the subject of the disease and its prevention. The fact that many of our patients were diagnosed in the late stage due to stigma and that diagnosis was largely made through scanning tests confirms the importance of these tests in early diagnosis. PMID:28149137

  20. Proton pump inhibitor failure in gastro-oesophageal reflux disease: a perspective aided by the Gartner hype cycle.

    PubMed

    Heading, Robert C

    2017-04-01

    Some patients with gastro-oesophageal reflux disease (GORD) experience symptoms despite proton pump inhibitor (PPI) treatment. In the early years of their availability, these drugs were thought to be a highly effective treatment for GORD and realisation that symptom relief was often incomplete came as a disappointment. This review considers the evolution of thinking with the aid of the Gartner hype cycle - a graphical depiction of the process of innovation, evolution and adoption of new technologies. Acknowledging that over-simplistic concepts of GORD have been largely responsible for inflated expectations of PPI therapy is an important step forward in establishing how patients with persistent symptoms, despite PPIs, should be assessed and treated.

  1. Failure analysis of laminated composites by using iterative three-dimensional finite element method

    NASA Astrophysics Data System (ADS)

    Hwang, W. C.; Sun, C. T.

    1989-05-01

    A failure analysis of laminated composites is accomplished by using an iterative three-dimensional finite element method. Based on Tsai-Wu failure theory, three different modes of failure are proposed: fiber breakage, matrix cracking, and delamination. The first ply failure load is then evaluated. As the applied load exceeds the first ply failure load, localized structural failure occurs and the global structural stiffness should change. The global stiffness matrix is modified by taking nonlinearity due to partial failures within a laminate into consideration. The first ply failure load is analyzed by using a iterative mixed field method in solving the linear part of the finite element equations. The progressive failure problem is solved numerically by using Newton-Raphson iterative schemes for the solution of nonlinear finite element equations. Numerical examples include angle-ply symmetric Thornel 300 graphite/934 resin epoxy laminates under uniaxial tension. First ply failure loads as well as the final failure loads are evaluated. Good correlation between analytical results and experimental data are observed. Numerical results also include the investigation of composite specimens with a centered hole, under uniaxial tension. Excellent correlation with the experimental data is observed.

  2. An analysis of drug resistance among people living with HIV/AIDS in Shanghai, China

    PubMed Central

    Sun, Meiyan; Sun, Jianjun; Lu, Hongzhou

    2017-01-01

    Background Understanding the mechanisms of drug resistance can facilitate better management of antiretroviral therapy, helping to prevent transmission and decrease the morbidity and mortality of people living with HIV/AIDS. However, there is little data about transmitted drug resistance and acquired drug resistance for HIV/AIDS patients in Shanghai. Methods A retrospective cohort study of HIV-infected patients who visited the Department of Infectious Disease from June 2008 to June 2015 was conducted in Shanghai, China. Logistic regression analysis was performed to analyze risk factors for drug resistance among HIV-infected people with virological failure. The related collected factors included patient age, gender, marital status, infection route, baseline CD4 count, antiretroviral therapy regimens, time between HIV diagnosis and initiating antiretroviral therapy. Factors with p<0.1 in the univariate logistic regression test were analyzed by multivariate logistic regression test. Results There were 575 subjects selected for this study and 369 participated in this research. For the antiretroviral therapy drugs, the rates of transmitted drug resistance and acquired drug resistance were significantly different. The non-nucleoside reverse transcriptase inhibitor (NNRTI) had the highest drug resistance rate (transmitted drug resistance, 10.9%; acquired drug resistance, 53.3%) and protease inhibitors (PIs) had the lowest drug resistance rate (transmitted drug resistance, 1.7%; acquired drug resistance, 2.7%). Logistic regression analysis found no factors that were related to drug resistance except marital status (married status for tenofovir: odds ratio = 6.345, 95% confidence interval = 1.553–25.921, P = 0.010) and the time span between HIV diagnosis and initiating antiretroviral therapy (≤6M for stavudine: odds ratio = 0.271, 95% confidence interval = 0.086–0.850, P = 0.025; ≤6M for didanosine: odds ratio = 0.284, 95% confidence interval = 0.096–0.842, P = 0

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

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

    SciTech Connect

    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.

  6. The distinct element analysis of toppling failure mechanisms

    NASA Astrophysics Data System (ADS)

    Özge Dinç, Şaziye; Sinan Işık, Nihat; Karaca, Zeki

    2016-04-01

    This project investigates the toppling failure mechanisms of rock masses having different rock materials and discontinuity properties in slopes that are designed in different heights. For this purpose, PFC2D as a distinct element code was used to anticipate the post failure behaviors of rock masses. After the simulation of laboratory tests on the samples in 2 (width) *4 (height) m, macro mechanical properties of rock masses were determined to be assigned the slopes. The properties of discontinuities were set up based on the smooth-joint method in PFC. The movements in the slopes -equipped with persistent and non-persistent discontinuities- were analyzed by using gravity increase method. The results show that the post failure behaviors of all rock samples have been controlled primarily by joint location and joint length. In addition to this, an increase on the slope height has an influence on the failure mechanism such that triggers the materials to transit from the toppling to circular yielding manner in some models. It has been also worth note that all models begin to fail as soon as the wing cracks develop by tension stresses, thus the tensile strength of the relevant rock material is the most critical mechanic parameter on the failure.

  7. Computer aided design and analysis of gear tooth geometry

    NASA Technical Reports Server (NTRS)

    Chang, S. H.; Huston, R. L.

    1987-01-01

    A simulation method for gear hobbing and shaping of straight and spiral bevel gears is presented. The method is based upon an enveloping theory for gear tooth profile generation. The procedure is applicable in the computer aided design of standard and nonstandard tooth forms. An inverse procedure for finding a conjugate gear tooth profile is presented for arbitrary cutter geometry. The kinematic relations for the tooth surfaces of straight and spiral bevel gears are proposed. The tooth surface equations for these gears are formulated in a manner suitable for their automated numerical development and solution.

  8. Does Federal Financial Aid Policy Influence the Institutional Aid Policies of Four-Year Colleges and Universities? An Exploratory Analysis

    ERIC Educational Resources Information Center

    Hossler, Don; Kwon, Jihye

    2015-01-01

    There is a dearth of empirical work that examines the relationships between federal financial aid policy and institutional financial aid priorities and expenditures. This study uses Resource Dependency Theory to explore whether changes the amount of financial aid awarded by colleges and universities during the last fifty years are best explained…

  9. Statistical failure analysis of adhesive resin cement bonded dental ceramics

    PubMed Central

    Wang, Yaou; Katsube, Noriko; Seghi, Robert R; Rokhlin, Stanislav I.

    2007-01-01

    The goal of this work is to quantitatively examine the effect of adhesive resin cement on the probability of crack initiation from the internal surface of ceramic dental restorations. The possible crack bridging mechanism and residual stress effect of the resin cement on the ceramic surface are examined. Based on the fracture-mechanics-based failure probability model, we predict the failure probability of glass-ceramic disks bonded to simulated dentin subjected to indentation loads. The theoretical predictions match experimental data suggesting that both resin bridging and shrinkage plays an important role and need to be considered for accurate prognostics to occur. PMID:18670583

  10. Investigation of TC-1 flight failure using power spectral analysis

    NASA Technical Reports Server (NTRS)

    Lorenzo, C. F.

    1976-01-01

    During the Titan Centaur 1 test flight a failure involving at least one of the Centaur propellant boost pumps occurred. Also, neither of the boost pump speed instruments indicated pump rotation. Accelerometer data from the Titan Centaur 1 flight failure were analyzed using power spectral density methods to determine boost pump speed during attempted starts of the Centaur. The technique was demonstrated on a reference flight. The hydrogen boost pump speed transient was determined for the TC-1 flight. Other trends are seen in the data. However, these are not believed to be the oxygen boost pump. Discussion of data enhancement techniques is also presented.

  11. Failure analysis of Chloride Silent Power, Ltd. PB cells

    NASA Astrophysics Data System (ADS)

    Beauchamp, E. K.

    1988-05-01

    Two beta double prime alumina electrolyte tubes from Chloride Silent Power, Ltd. PB cells which failed in testing at Sandia National Laboratories, showed extensive cracking. The cracks initiated at the interior surface under localized stress apparently resulting from nonuniform ionic currents. The nonuniform currents apparently were a result of nonuniform wetting of the interior surface of the electrolyte. Failure of the sodium electrode seal, which introduced contaminants to the electrolyte surface, may have been reponsible for the nonuniform wetting. In one of the electrolytes, large grains, produced by overfiring, contributed to the failure.

  12. The HIV/AIDS caregiver identity as a double-edged sword: a discourse analysis on HIV/AIDS caregiving in South Africa.

    PubMed

    Ranjbar, Vania

    2014-09-01

    This article discusses the identity of HIV/AIDS caregivers as constructed by a group of HIV/AIDS caregivers at a non-profit organisation in South Africa. During a 12-month period data were collected through interviews with the organisation's staff and volunteers. Using discourse analysis, the study identified a caregiver identity constructed by participants. This caregiving identity acts as a double-edged sword: while the rewards of caregiving act as a buffer against stressful experiences, the prescriptive nature of the caregiver identity is taxing, and may explain burnout among HIV/AIDS caregivers. The study concludes that for support systems for HIV/AIDS caregivers to be effective, the social culture and identity of HIV/AIDS caregivers must be considered.

  13. Application of the cubic polynomial strength criterion to the failure analysis of composite materials

    NASA Technical Reports Server (NTRS)

    Tennyson, R. C.; Nanyaro, A. P.; Wharram, G. E.

    1980-01-01

    A comparative failure analysis is presented based on the application of quadratic and cubic forms of the tensor polynomial lamina strength criterion to various composite structural configurations in a plane stress state. Failure loads have been predicted for off-angle laminates under simple loading conditions and for symmetric-balanced laminates subject to varying degrees of biaxial tension, including configurations subject to multimode failures. Some experimental data are also provided to support these calculations. From these results, the necessity of employing a cubic strength criterion to accurately predict the failure of composite laminae is demonstrated.

  14. Ferrographic and spectrographic analysis of oil sampled before and after failure of a jet engine

    NASA Technical Reports Server (NTRS)

    Jones, W. R., Jr.

    1980-01-01

    An experimental gas turbine engine was destroyed as a result of the combustion of its titanium components. Several engine oil samples (before and after the failure) were analyzed with a Ferrograph as well as plasma, atomic absorption, and emission spectrometers. The analyses indicated that a lubrication system failure was not a causative factor in the engine failure. Neither an abnormal wear mechanism, nor a high level of wear debris was detected in the oil sample from the engine just prior to the test in which the failure occurred. However, low concentrations of titanium were evident in this sample and samples taken earlier. After the failure, higher titanium concentrations were detected in oil samples taken from different engine locations. Ferrographic analysis indicated that most of the titanium was contained in spherical metallic debris after the failure.

  15. Analysis of failures and poor results of lumbar spine surgery.

    PubMed

    Fager, C A; Freidberg, S R

    1980-01-01

    The failures and poor results of lumbar spine surgery are analyzed in a retrospectively study of 105 consecutive patients referred to the authors for evaluation during 1976. Those who had a history of industrial or vehicular accident outnumbered others by about two to one. Review of histories, physical findings, and myelograms in most of the patients failed to substantiate the diagnosis of ruptured disc or nerve root compression. Many of the failures occurred in thos patients in whom little if any evidence of nerve root compression was found. The indications for surgery were poor in this group. Other failures occurred in patients who had improper, incomplete, or inadequate operations, especially those with lumbar spondylosis, a retained fragment of disc, or surgery at the wrong level. In addition to failure, poor results were recorded in patients who had significant nerve root or cauda equina injury from surgery, associated "arachnoiditis" which is thought to result from surgical trauma in many instances, or multiple operations leading to a hopelessly disabled state.

  16. Discordance between genotypic resistance and pseudovirus phenotypic resistance in AIDS patients after long-term antiretroviral therapy and virological failure.

    PubMed

    Yang, Jing; Geng, Wenqing; Zhang, Min; Han, Xiaoxu; Shang, Hong

    2014-10-01

    Sixteen original recombinant pseudoviruses were generated by cloning the reverse transcriptase and protease genes of human immunodeficiency virus (HIV)-1 from patients into a plasmid vector (pNL4-3-ΔE-EGFP). By site-directed mutagenesis two restriction endonuclease sites, ApaI and AgeI, were inserted into pNL4-3-ΔE-EGFP. Phenotypic susceptibility of recombinant pseudoviruses to five different classes of antiretroviral drugs was determined using a luciferase reporter assay system. The results were subjected to comparative analyses to detect genotype-phenotype associations. Among 16 strains tested, 12 strains had a discordant genotype-phenotype resistance pattern to at least one drug. In five strains resistance to two, in two strains to three, and in one strain resistance to four drugs was detected. HIV resistance genotyping could predict the phenotype for nevirapine and azidothymidine. For lamivudine, 2'-3'-didehydro-2'-3'dideoxythymidine and didanosine, phenotypic resistance testing was necessary. The study showed that in patients who experienced long-term highly active antiretroviral therapy and virological failure, there is some discordance between genotypic and phenotypic HIV drug resistance. To address the issue of limited resources in China, genotypic and phenotypic resistance testing should be done for different drugs in order to guide clinical therapy more effectively.

  17. Factor Configurations with Governance as Conditions for Low HIV/AIDS Prevalence in HIV/AIDS Recipient Countries: Fuzzy-set Analysis.

    PubMed

    Lee, Hwa-Young; Yang, Bong-Min; Kang, Minah

    2015-11-01

    This paper aims to investigate whether good governance of a recipient country is a necessary condition and what combinations of factors including governance factor are sufficient for low prevalence of HIV/AIDS in HIV/AIDS aid recipient countries during the period of 2002-2010. For this, Fuzzy-set Qualitative Comparative Analysis (QCA) was used. Nine potential attributes for a causal configuration for low HIV/AIDS prevalence were identified through a review of previous studies. For each factor, full membership, full non-membership, and crossover point were specified using both author's knowledge and statistical information of the variables. Calibration and conversion to a fuzzy-set score were conducted using Fs/QCA 2.0 and probabilistic tests for necessary and sufficiency were performed by STATA 11. The result suggested that governance is the necessary condition for low prevalence of HIV/AIDS in a recipient country. From sufficiency test, two pathways were resulted. The low level of governance can lead to low level of HIV/AIDS prevalence when it is combined with other favorable factors, especially, low economic inequality, high economic development and high health expenditure. However, strengthening governance is a more practical measure to keep low prevalence of HIV/AIDS because it is hard to achieve both economic development and economic quality. This study highlights that a comprehensive policy measure is the key for achieving low prevalence of HIV/AIDS in recipient country.

  18. Factor Configurations with Governance as Conditions for Low HIV/AIDS Prevalence in HIV/AIDS Recipient Countries: Fuzzy-set Analysis

    PubMed Central

    Lee, Hwa-Young; Kang, Minah

    2015-01-01

    This paper aims to investigate whether good governance of a recipient country is a necessary condition and what combinations of factors including governance factor are sufficient for low prevalence of HIV/AIDS in HIV/AIDS aid recipient countries during the period of 2002-2010. For this, Fuzzy-set Qualitative Comparative Analysis (QCA) was used. Nine potential attributes for a causal configuration for low HIV/AIDS prevalence were identified through a review of previous studies. For each factor, full membership, full non-membership, and crossover point were specified using both author's knowledge and statistical information of the variables. Calibration and conversion to a fuzzy-set score were conducted using Fs/QCA 2.0 and probabilistic tests for necessary and sufficiency were performed by STATA 11. The result suggested that governance is the necessary condition for low prevalence of HIV/AIDS in a recipient country. From sufficiency test, two pathways were resulted. The low level of governance can lead to low level of HIV/AIDS prevalence when it is combined with other favorable factors, especially, low economic inequality, high economic development and high health expenditure. However, strengthening governance is a more practical measure to keep low prevalence of HIV/AIDS because it is hard to achieve both economic development and economic quality. This study highlights that a comprehensive policy measure is the key for achieving low prevalence of HIV/AIDS in recipient country. PMID:26617451

  19. Analysis of Mechanical Failure of Polymer Microneedles by Axial Force.

    PubMed

    Park, Jung-Hwan; Prausnitz, Mark R

    2010-04-01

    A polymeric microneedle has been developed for drug delivery applications. The ultimate goal of the polymeric microneedle is insertion into the specified region without failure for effective transdermal drug delivery. Mechanical failure of various geometries of microneedles by axial load was modeled using the Euler formula and the Johnson formula to predict the failure force of tapered-column microneedles. These formulas were compared with measured data to identify the mechanical behavior of microneedles by determining the critical factors including the actual length and end-fixed factor. The comparison of the two formulas with the data showed good agreement at the end-fixity (K) of 0.7. This value means that a microneedle column has one fixed end and one pinned end, and that part of the microneedle was overloaded by axial load. When the aspect ratio of length to equivalent diameter is 12:1 at 3 GPa of Young's modulus, there is a transition from the Euler region to the Johnson region by the decreased length and increased base diameter of the microneedle. A polymer having less than 3 GPa of stiffness would follow the Euler formula. A 12:1 aspect ratio of length to equivalent diameter of the microneedle was the mechanical indicator determining the failure mode between elastic buckling and inelastic buckling at less than 3 GPa of Young's modulus of polymer. Microneedles with below a 12:1 aspect ratio of length-to-equivalent diameter and more than 3 GPa of Young's were recommended for reducing sudden failure by buckling and for successfully inserting the microneedle into the skin.

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

    NASA Astrophysics Data System (ADS)

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

    2012-04-01

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

  1. Probabilistic low cycle fatigue failure analysis with application to liquid propellant rocket engines

    NASA Technical Reports Server (NTRS)

    Newlin, L.; Sutharshana, S.; Ebbeler, D.; Moore, N.; Fox, E.

    1990-01-01

    A probabilistic Low Cycle Fatigue (LCF) failure analysis of a candidate turbine disk for use in a turbopump of a rocket engine of the Space Shuttle Main Engine class is described. A state-of-the-art LCF failure prediction method was used in a Monte Carlo simulation to generate a distribution of failure lives. A stochastic Stress/Life (S/N) model was used for materials characterization. The LCF failure model expresses fatigue life as a function of stochastic parameters including environmental parameters, loads, material properties, structural parameters, and model specification errors. The rationale for the particular characterization of each stochastic input parameter is described. The results and interpretation of the failure analysis are given.

  2. The use of failure mode effect and criticality analysis in a medication error subcommittee.

    PubMed

    Williams, E; Talley, R

    1994-04-01

    Failure Mode Effect and Criticality Analysis (FMECA) is the systematic assessment of a process or product that enables one to determine the location and mechanism of potential failures. It has been used by engineers, particularly in the aerospace industry, to identify and prioritize potential failures during product development when there is a lack of data but an abundance of expertise. The Institute for Safe Medication Practices has recommended its use in analyzing the medication administration process in hospitals and in drug product development in the pharamceutical industry. A medication error subcommittee adopted and modified FMECA to identify and prioritize significant failure modes in its specific medication administration process. Based on this analysis, the subcommittee implemented solutions to four of the five highest ranked failure modes. FMECA provided a method for a multidisciplinary group to address the most important medication error concerns based upon the expertise of the group members. It also facilitated consensus building in a group with varied perceptions.

  3. Task Analysis for Health Occupations. Cluster: Nursing. Occupation: Home Health Aide. Education for Employment Task Lists.

    ERIC Educational Resources Information Center

    Lake County Area Vocational Center, Grayslake, IL.

    This document contains a task analysis for health occupations (home health aid) in the nursing cluster. For each task listed, occupation, duty area, performance standard, steps, knowledge, attitudes, safety, equipment/supplies, source of analysis, and Illinois state goals for learning are listed. For the duty area of "providing therapeutic…

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

    NASA Astrophysics Data System (ADS)

    Hunt, Ronderio LaDavis

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

  5. Case–Cohort Analysis with Accelerated Failure Time Model

    PubMed Central

    Kong, Lan; Cai, Jianwen

    2010-01-01

    Summary In a case–cohort design, covariates are assembled only for a subcohort that is randomly selected from the entire cohort and any additional cases outside the subcohort. This design is appealing for large cohort studies of rare disease, especially when the exposures of interest are expensive to ascertain for all the subjects. We propose statistical methods for analyzing the case–cohort data with a semiparametric accelerated failure time model that interprets the covariates effects as to accelerate or decelerate the time to failure. Asymptotic properties of the proposed estimators are developed. The finite sample properties of case–cohort estimator and its relative efficiency to full cohort estimator are assessed via simulation studies. A real example from a study of cardiovascular disease is provided to illustrate the estimating procedure. PMID:18537948

  6. Summary of failure analysis activities at Brookhaven National Laboratory

    SciTech Connect

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

    1996-10-01

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

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

    DTIC Science & Technology

    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

  8. The Application of Failure Modes and Effects Analysis Methodology to Intrathecal Drug Delivery for Pain Management

    PubMed Central

    Patel, Teresa; Fisher, Stanley P.

    2016-01-01

    Objective This study aimed to utilize failure modes and effects analysis (FMEA) to transform clinical insights into a risk mitigation plan for intrathecal (IT) drug delivery in pain management. Methods The FMEA methodology, which has been used for quality improvement, was adapted to assess risks (i.e., failure modes) associated with IT therapy. Ten experienced pain physicians scored 37 failure modes in the following categories: patient selection for therapy initiation (efficacy and safety concerns), patient safety during IT therapy, and product selection for IT therapy. Participants assigned severity, probability, and detection scores for each failure mode, from which a risk priority number (RPN) was calculated. Failure modes with the highest RPNs (i.e., most problematic) were discussed, and strategies were proposed to mitigate risks. Results Strategic discussions focused on 17 failure modes with the most severe outcomes, the highest probabilities of occurrence, and the most challenging detection. The topic of the highest‐ranked failure mode (RPN = 144) was manufactured monotherapy versus compounded combination products. Addressing failure modes associated with appropriate patient and product selection was predicted to be clinically important for the success of IT therapy. Conclusions The methodology of FMEA offers a systematic approach to prioritizing risks in a complex environment such as IT therapy. Unmet needs and information gaps are highlighted through the process. Risk mitigation and strategic planning to prevent and manage critical failure modes can contribute to therapeutic success. PMID:27477689

  9. Reciprocating compressor valve failure -- Digital modelling and analysis

    SciTech Connect

    Motriuk, R.W.

    1996-12-31

    Many problems in reciprocating compressors are caused by valve failures. Usually, valve failures are diagnosed early, and the worn out parts are replaced. This requires, however, unscheduled compressor shutdowns which increase the cost of operation and possibly breach gas delivery contracts. Thus, it is essential to design valves adequate for the particular compressors and flow conditions. In this paper, it is determined that the cause of an unusually large number of valve failures at one of the NOVA Gas Transmission Limited (NGTL) compressor stations was an inadequate valve design. It is shown that the type of valve presently used is unacceptable and should be replaced. Due to economic restrictions, however, the existing valves are modified rather than replaced. The method used to re-design the compressor valves includes two steps: field measurements and computer digital modelling. The modelling incorporates: (1) acoustic simulation of the system, (2) compressor valve dynamic simulation, and (3) simultaneous simulation of fluid solid interactions between the compressor valves, compressor cylinders and pipework. The results obtained by using models of (2) and (3) are compared.

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

    NASA Technical Reports Server (NTRS)

    Felt, Frederick S.

    2005-01-01

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

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

    SciTech Connect

    Zhang, Chao; Santhanagopalan, Shriram; Pesaran, Ahmad

    2016-07-28

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

  12. A survey of compiler development aids. [concerning lexical, syntax, and semantic analysis

    NASA Technical Reports Server (NTRS)

    Buckles, B. P.; Hodges, B. C.; Hsia, P.

    1977-01-01

    A theoretical background was established for the compilation process by dividing it into five phases and explaining the concepts and algorithms that underpin each. The five selected phases were lexical analysis, syntax analysis, semantic analysis, optimization, and code generation. Graph theoretical optimization techniques were presented, and approaches to code generation were described for both one-pass and multipass compilation environments. Following the initial tutorial sections, more than 20 tools that were developed to aid in the process of writing compilers were surveyed. Eight of the more recent compiler development aids were selected for special attention - SIMCMP/STAGE2, LANG-PAK, COGENT, XPL, AED, CWIC, LIS, and JOCIT. The impact of compiler development aids were assessed some of their shortcomings and some of the areas of research currently in progress were inspected.

  13. A Tool To Support Failure Mode And Effects Analysis Based On Causal Modelling And Reasoning

    NASA Astrophysics Data System (ADS)

    Underwood, W. E.; Laib, S. L.

    1987-05-01

    A prototype knowledge-based system has been developed that supports Failure Mode & Effects Analysis (FMEA). The knowledge base consists of causal models of components and a representation for coupling these components into assemblies and systems. The causal models are qualitative models. They allow reasoning as to whether variables are increasing, decreasing or steady. The analysis strategies used by the prototype allow it to determine the effects of failure modes on the function of the part, the failure effect on the assembly the part is contained in, and the effect on the subsystem containing the assembly.

  14. Initial Review of Methods for Cascading Failure Analysis in Electric Power Transmission Systems

    SciTech Connect

    Baldick, R.; Chowdhury, Badrul; Dobson, Ian; Dong, Zhao Yang; Gou, Bei; Hawkins, David L.; Huang, Zhenyu; Joung, Manho; Kirschen, Daniel; Li, Fangxing; Li, Juan; Li, Zuyi; Liu, Chen-Ching; Mili, Lamine; Miller, Stephen; Podmore, Robin; Schneider, Kevin P.; Sun, Kai; Wang, David; Wu, Zhigang; Zhang, Pei; Zhang, Wenjie; Zhang, Xiaoping

    2008-09-09

    Large blackouts are typically caused by cascading failure propagating through a power system by means of a variety of processes. Because of the wide range of time scales, mulitple interacting processes, and the hugh number of possible interactions, the simulation and analysis of cascading blackouts is extremely complicated. This paper defines cascading failure for blackouts and gives an initial review of the current understanding, industrial tools, and the challenges and emerging methods of analysis and simulation.

  15. A handheld computer-aided diagnosis system and simulated analysis

    NASA Astrophysics Data System (ADS)

    Su, Mingjian; Zhang, Xuejun; Liu, Brent; Su, Kening; Louie, Ryan

    2016-03-01

    This paper describes a Computer Aided Diagnosis (CAD) system based on cellphone and distributed cluster. One of the bottlenecks in building a CAD system for clinical practice is the storage and process of mass pathology samples freely among different devices, and normal pattern matching algorithm on large scale image set is very time consuming. Distributed computation on cluster has demonstrated the ability to relieve this bottleneck. We develop a system enabling the user to compare the mass image to a dataset with feature table by sending datasets to Generic Data Handler Module in Hadoop, where the pattern recognition is undertaken for the detection of skin diseases. A single and combination retrieval algorithm to data pipeline base on Map Reduce framework is used in our system in order to make optimal choice between recognition accuracy and system cost. The profile of lesion area is drawn by doctors manually on the screen, and then uploads this pattern to the server. In our evaluation experiment, an accuracy of 75% diagnosis hit rate is obtained by testing 100 patients with skin illness. Our system has the potential help in building a novel medical image dataset by collecting large amounts of gold standard during medical diagnosis. Once the project is online, the participants are free to join and eventually an abundant sample dataset will soon be gathered enough for learning. These results demonstrate our technology is very promising and expected to be used in clinical practice.

  16. Computer Aided Setup Planning Using Tolerance Analysis for Prismatic Components

    NASA Astrophysics Data System (ADS)

    Vahid, Abedini; Mohsen, Shakeri; Sajad, Kafashi

    2011-01-01

    Computer aided process planning (CAPP) is the bridge between CAD and CAM. Setup planning is the major key to transform design concept into manufacturing domain, which is mainly experience based activity in modern manufacturing industry. Setup planning is a complicated non-linear task constrained by many factors such as tool approach direction, geometric feature relationship, fixturing constrain, tolerance requirement and manufacturing practice. The objective of setup planning is to determine the number of setup needed, the orientation of the workpiece and the machining surfaces in each setup. This paper focuses on the development of a formalized procedure for automatic generation of setup plan. Tolerance relations are used as critical constraints for setup planning. The tasks that are performed are: (a) identifying groups of features that can be machined in a single setup, (b) determining a suitable work piece orientation, i.e. the suitable datum planes for each setup, (c) determining all the feasible setup plans to machine the given set of features of prismatic parts, and (d) evaluating the feasible setup plans on the basis of technological conditions. Trial runs with industrial parts indicate that the system is applicable for industrial use.

  17. Quantitative analysis of ultrasound images for computer-aided diagnosis

    PubMed Central

    Wu, Jie Ying; Tuomi, Adam; Beland, Michael D.; Konrad, Joseph; Glidden, David; Grand, David; Merck, Derek

    2016-01-01

    Abstract. We propose an adaptable framework for analyzing ultrasound (US) images quantitatively to provide computer-aided diagnosis using machine learning. Our preliminary clinical targets are hepatic steatosis, adenomyosis, and craniosynostosis. For steatosis and adenomyosis, we collected US studies from 288 and 88 patients, respectively, as well as their biopsy or magnetic resonanceconfirmed diagnosis. Radiologists identified a region of interest (ROI) on each image. We filtered the US images for various texture responses and use the pixel intensity distribution within each ROI as feature parameterizations. Our craniosynostosis dataset consisted of 22 CT-confirmed cases and 22 age-matched controls. One physician manually measured the vectors from the center of the skull to the outer cortex at every 10 deg for each image and we used the principal directions as shape features for parameterization. These parameters and the known diagnosis were used to train classifiers. Testing with cross-validation, we obtained 72.74% accuracy and 0.71 area under receiver operating characteristics curve for steatosis (p<0.0001), 77.27% and 0.77 for adenomyosis (p<0.0001), and 88.63% and 0.89 for craniosynostosis (p=0.0006). Our framework is able to detect a variety of diseases with high accuracy. We hope to include it as a routinely available support system in the clinic. PMID:26835502

  18. Failure Mode Analysis of V-Shaped Pyrotechnically Actuated Valves

    NASA Technical Reports Server (NTRS)

    Sachdev, Jai S.; Hosangadi, A.; Chenoweth, James D.; Saulsberry, Regor L.; McDougle, Stephen H.

    2012-01-01

    Current V-shaped stainless steel pyrovalve initiators have rectified many of the deficiencies of the heritage Y-shaped aluminum design. However, a credible failure mode still exists for dual simultaneous initiator (NSI) firings in which low temperatures were detected at the booster cap and less consistent ignition was observed than when a single initiator was fired. In order to asses this issue, a numerical framework has been developed for predicting the flow through pyrotechnically actuated valves. This framework includes a fully coupled solution of the gas-phase equation with a non-equilibrium dispersed phase for solid particles as well as the capability to model conjugate gradient heat transfer to the booster cap. Through a hierarchy of increasingly complex simulations, a hypothesis for the failure mode of the nearly simultaneous dual NSI firings has been proven. The simulations indicate that the failure mode for simultaneous dual NSI firings may be caused by flow interactions between the flame channels. The shock waves from each initiator interact in the booster cavity resulting in a high pressure that prevents the gas and particulate velocity from rising in the booster cap region. This impedes the bulk of the particulate phase from impacting the booster cap and reduces the heat transfer to the booster cap since the particles do not impact it. Heat transfer calculations to the solid metal indicate that gas-phase convective heat transfer may not be adequate by itself and that energy transfer from the particulate phase may be crucial for the booster cap burn through.

  19. Progressive Failure Analysis of Laminated Composite Plates with Elliptical or Circular Cutout Using Finite Element Method

    NASA Astrophysics Data System (ADS)

    Lakshminarayana, A.; Vijayakumar, R.; Krishnamohana Rao, G.

    2016-09-01

    The progressive failure analysis of symmetrically laminated composite plate [0°/+45°/-45°/90°]2s with circular or elliptical cutout under uniform uniaxial compression loading is carried out using finite element method. Hashin's failure criterion is used to predict the lamina failure. A parametric study has been carried out to study the effect of elliptical / circular cutout orientation, cutout size and plate thickness on the ultimate failure load of laminated composite plate under uni-axial compression loading. It is noticed that elliptical cutout orientation has influence on the strength of the notched composite plates. It is observed that the laminate size of the elliptical/circular cutout and plate thickness has substantial influence on the ultimate failure load of notched composite plates.

  20. Analysis for the Progressive Failure Response of Textile Composite Fuselage Frames

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.; Boitnott, Richard L. (Technical Monitor)

    2002-01-01

    A part of aviation accident mitigation is a crash worthy airframe structure, and an important measure of merit for a crash worthy structure is the amount of kinetic energy that can be absorbed in the crush of the structure. Prediction of the energy absorbed from finite element analyses requires modeling the progressive failure sequence. Progressive failure modes may include material degradation, fracture and crack growth, and buckling and collapse. The design of crash worthy airframe components will benefit from progressive failure analyses that have been validated by tests. The subject of this research is the development of a progressive failure analysis for textile composite. circumferential fuselage frames subjected to a quasi-static, crash-type load. The test data for these frames are reported, and these data, along with stub column test data, are to be used to develop and to validate methods for the progressive failure response.

  1. Analysis for the Progressive Failure Response of Textile Composite Fuselage Frames

    NASA Technical Reports Server (NTRS)

    Johnson, Eric R.; Boitnott, Richard L. (Technical Monitor)

    2002-01-01

    A part of aviation accident mitigation is a crashworthy airframe structure, and an important measure of merit for a crashworthy structure is the amount of kinetic energy that can be absorbed in the crush of the structure. Prediction of the energy absorbed from finite element analyses requires modeling the progressive failure sequence. Progressive failure modes may include material degradation, fracture and crack growth, and buckling and collapse. The design of crashworthy airframe components will benefit from progressive failure analyses that have been validated by tests. The subject of this research is the development of a progressive failure analysis for a textile composite, circumferential fuselage frame subjected to a quasi-static, crash-type load. The test data for the frame are reported, and these data are used to develop and to validate methods for the progressive failure response.

  2. Creep failure analysis for ceramic composites containing viscous interfaces

    SciTech Connect

    Beyerlein, I.J.; An, L.; Raj, R.

    1998-09-01

    This paper describes an experimental and theoretical study of the creep fracture of advanced ceramic composites under steady axial tension. Such composites consist of a high fraction of elongated ceramic grains, varying substantially in aspect ratio and embedded in a glassy matrix phase. For creep testing, a model test system was prepared, which consisted of well-aligned elongated mica platelets ({approximately} 60 vol%) and residual glass phase ({approximately} 40 vol%) in its final heat-treatment stage. The creep curves of several specimens under various applied loads and at a temperature (800 C) higher than the T{sub g} of the glass matrix ({approximately} 650 C) were obtained up to creep fracture. Micrographs of the creep fracture surfaces revealed substantial grain pull-out and cavitation in the matrix phase with virtually no transgranular fracture. The objective of this work is to simulate the creep response and fracture based on the accumulation of localized void growth and microstructural parameters, using a computational mechanics technique, called viscous break interaction (VBI), developed to compute stress fields around strongly interacting fractures or voids in composites with fibrous microstructures. To simulate the creep process up to fracture, a Monte Carlo model is developed which couples VBI with a statistical description of grain length. Both the experimental and simulation results show that random lengths and random overlap of the aligned grains naturally lead to (i) local and microstructure-sensitive damage evolution up to ultimate failure and (ii) substantial variation in failure times of seemingly identical specimens.

  3. Computer-aided-analysis of linear control system robustness

    NASA Technical Reports Server (NTRS)

    Stengel, Robert F.; Ray, Laura R.

    1990-01-01

    Stochastic robustness is a simple technique used to estimate the stability and performance robustness of linear, time-invariant systems. The use of high-speed graphics workstations and control system design software in stochastic robustness analysis is discussed and demonstrated. It is shown that stochastic robustness makes good use of modern computational and graphic tools, and it is easily implemented using commercial control system design and analysis software.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Technical Reports Server (NTRS)

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

    1992-01-01

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

  6. How sustainable is Japan's foreign aid policy? An analysis of Japan's official development assistance and funding for energy sector projects

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Hideka

    Japan has adopted a sustainable development strategy since the late 1980s in the effort to address social and environmental damages caused by past Japan-funded projects in partner nations. Even after about a decade and a half of the policy implementation, however, there are few reports which critically examine effects of the adoption of the idea of sustainable development. This dissertation evaluates Japan's foreign aid policy to determine the extent to which new revisions of aid policy have improved the environmental sustainability of the policy. This dissertation reviews the mainstream idea of sustainable development (also known as the sustainable development paradigm in this dissertation) to reveal the nature of the idea of sustainable development that Japan's foreign aid policy depends on. A literature review of two development discourses---modernization theory and ecological modernization theory---and three types of critiques against the sustainable development paradigm---focused on adverse impacts of modern science, globalization, and environmental overuse---reveals core logics of and problems with the sustainable development paradigm. Japan's foreign aid policy impacts on energy sector development in recipient countries is examined by means of a quantitative analysis and a qualitative analysis. Specifically, it examines the effect of Japan's ODA program over fifteen years that proposed to facilitate sustainable development in developing countries. Special emphasis is given to investigation of ODA disbursements in the energy sector and detailed case studies of several individual energy projects are performed. The dissertation discovers that the sustainable development paradigm guiding Japan's ODA has little capacity to accomplish its goals to bring about social and ecological improvement in developing countries. This dissertation finds three fundamental weaknesses in Japanese ODA policy on energy sector development as well as the sustainable development

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

    NASA Astrophysics Data System (ADS)

    Tianen, Matthew N.

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

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

    NASA Astrophysics Data System (ADS)

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

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

  9. 78 FR 300 - IDEXX Laboratories, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-03

    ... [Federal Register Volume 78, Number 2 (Thursday, January 3, 2013)] [Notices] [Pages 300-303] [FR Doc No: 2012-31571] FEDERAL TRADE COMMISSION [File No. 101 0023] IDEXX Laboratories, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade Commission. ACTION: Proposed...

  10. 77 FR 50508 - Brain-Pad, Inc; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-21

    ... Brain-Pad, Inc; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade... SUPPLEMENTARY INFORMATION section below. Write ``Brain-Pad, File No. 122 3073'' on your comment, and file your... must receive it on or before September 17, 2012. Write ``Brain-Pad, File No. 122 3073'' on your...

  11. 63 FR 69292 - Max F. James; Analysis to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    1998-12-16

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION Max F. James; Analysis to Aid Public Comment AGENCY: Federal Trade Commission. ACTION: Proposed Consent... final approval, to a proposed consent order from Max F. James (hereinafter ``James'' or...

  12. 77 FR 17479 - Star Pipe Products, Ltd.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-26

    ... Star Pipe Products, Ltd.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal... SUPPLEMENTARY INFORMATION section below. Write ``Star Pipe, Docket No. 9351'' on your comment, and file your... receive it on or before April 20, 2012. Write ``Star Pipe, Docket No. 9351'' on your comment. Your...

  13. 77 FR 64519 - Magnesium Elektron; Analysis of Agreement Containing Consent Orders To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-22

    ... Magnesium Elektron; Analysis of Agreement Containing Consent Orders To Aid Public Comment AGENCY: Federal... INFORMATION section below. Write ``Magnesium Elektron, File No. 091 0094'' on your comment and file your... November 13, 2012. Write ``Magnesium Elektron, File No. 091 0094'' on your comment. Your comment...

  14. 78 FR 46950 - Ecobaby Organics, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ... Ecobaby Organics, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... Write ``Ecobaby Organics, File No. 122 3129'' on your comment and file your comment online at https... consider your comment, we must receive it on or before August 26, 2013. Write ``Ecobaby Organics, File...

  15. SMART USE OF COMPUTER-AIDED SPERM ANALYSIS (CASA) TO CHARACTERIZE SPERM MOTION

    EPA Science Inventory

    Computer-aided sperm analysis (CASA) has evolved over the past fifteen years to provide an objective, practical means of measuring and characterizing the velocity and parttern of sperm motion. CASA instruments use video frame-grabber boards to capture multiple images of spermato...

  16. Minnesota Computer Aided Library System (MCALS); University of Minnesota Subsystem Cost/Benefits Analysis.

    ERIC Educational Resources Information Center

    Lourey, Eugene D., Comp.

    The Minnesota Computer Aided Library System (MCALS) provides a basis of unification for library service program development in Minnesota for eventual linkage to the national information network. A prototype plan for communications functions is illustrated. A cost/benefits analysis was made to show the cost/effectiveness potential for MCALS. System…

  17. Graphical and Normative Analysis of Binocular Vision by Mini Computer: A Teaching Aid and Clinical Tool.

    ERIC Educational Resources Information Center

    Kees, Martin; Schor, Clifton

    1981-01-01

    An inexpensive computer graphics systems (Commodore PET), used as a video aid for teaching students advanced case analysis, is described. The course provides students with the analytical tools for evaluating with graphical and statistical techniques and treating with lenses, prisms, and orthoptics various anomalies of binocular vision. (MLW)

  18. 75 FR 10798 - Richard J. Stanton; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-09

    ... Richard J. Stanton; Analysis of Proposed Consent Order to Aid Public Comment AGENCY: Federal Trade... invited to submit written comments electronically or in paper form. Comments should refer to ``Richard J... ``Richard J. Stanton, File No. 072 3165'' reference both in the text and on the envelope, and should...

  19. 77 FR 14523 - Western Digital Corporation; Analysis of Agreement Containing Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-12

    ... Western Digital Corporation; Analysis of Agreement Containing Consent Order to Aid Public Comment AGENCY... Comment part of the SUPPLEMENTARY INFORMATION section below. Write ``Western Digital, File No. 111 0122... consider your comment, we must receive it on or before April 4, 2012. Write ``Western Digital, File No....

  20. 48 CFR 915.404-2-70 - Audit as an aid in proposal analysis.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... Audit as an aid in proposal analysis. (a) When a contract price will be based on cost or pricing data... (2) $1,000,000 for all other contract types, including initial prices, estimated costs of cost-reimbursement contracts, interim and final price redeterminations, and target and settlement of...

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

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

  2. Failure Behavior Characterization of Mo-Modified Ti Surface by Impact Test and Finite Element Analysis

    NASA Astrophysics Data System (ADS)

    Ma, Yong; Qin, Jianfeng; Zhang, Xiangyu; Lin, Naiming; Huang, Xiaobo; Tang, Bin

    2015-07-01

    Using the impact test and finite element simulation, the failure behavior of the Mo-modified layer on pure Ti was investigated. In the impact test, four loads of 100, 300, 500, and 700 N and 104 impacts were adopted. The three-dimensional residual impact dents were examined using an optical microscope (Olympus-DSX500i), indicating that the impact resistance of the Ti surface was improved. Two failure modes cohesive and wearing were elucidated by electron backscatter diffraction and energy-dispersive spectrometer performed in a field-emission scanning electron microscope. Through finite element forward analysis performed at a typical impact load of 300 N, stress-strain distributions in the Mo-modified Ti were quantitatively determined. In addition, the failure behavior of the Mo-modified layer was determined and an ideal failure model was proposed for high-load impact, based on the experimental and finite element forward analysis results.

  3. Computer-aided analysis of Riemann sheet structures

    NASA Astrophysics Data System (ADS)

    van Hameren, André; Kleiss, Ronald

    1999-02-01

    We report on experience with an investigation of the analytic structure of the solution of certain algebraic complex equations. In particular the behavior of their series expansions around the origin is discussed. The investigation imposes the need for an analysis of the singularities and the Riemann sheets of the solution, in which numerical methods are used.

  4. Stress analysis and failure of an internally pressurized composite-jacketed steel cylinder

    NASA Technical Reports Server (NTRS)

    Chen, Peter C. T.

    1992-01-01

    This paper presents a nonlinear stress analysis of a thick-walled compound tube subjected to internal pressure. The compound tube is constructed of a steel liner and a graphite-bismaleimide outer shell. Analytical expressions for the stresses, strains, and displacements are derived for all loading ranges up to failure. Numerical results for the stresses and the maximum value that the compound tube can contain without failure are presented.

  5. A Method for Microalgae Proteomics Analysis Based on Modified Filter-Aided Sample Preparation.

    PubMed

    Li, Song; Cao, Xupeng; Wang, Yan; Zhu, Zhen; Zhang, Haowei; Xue, Song; Tian, Jing

    2017-04-11

    With the fast development of microalgal biofuel researches, the proteomics studies of microalgae increased quickly. A filter-aided sample preparation (FASP) method is widely used proteomics sample preparation method since 2009. Here, a method of microalgae proteomics analysis based on modified filter-aided sample preparation (mFASP) was described to meet the characteristics of microalgae cells and eliminate the error caused by over-alkylation. Using Chlamydomonas reinhardtii as the model, the prepared sample was tested by standard LC-MS/MS and compared with the previous reports. The results showed mFASP is suitable for most of occasions of microalgae proteomics studies.

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

    NASA Astrophysics Data System (ADS)

    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

  7. Computer-aided communication satellite system analysis and optimization

    NASA Technical Reports Server (NTRS)

    Stagl, T. W.; Morgan, N. H.; Morley, R. E.; Singh, J. P.

    1973-01-01

    The capabilities and limitations of the various published computer programs for fixed/broadcast communication satellite system synthesis and optimization are discussed. A satellite Telecommunication analysis and Modeling Program (STAMP) for costing and sensitivity analysis work in application of communication satellites to educational development is given. The modifications made to STAMP include: extension of the six beam capability to eight; addition of generation of multiple beams from a single reflector system with an array of feeds; an improved system costing to reflect the time value of money, growth in earth terminal population with time, and to account for various measures of system reliability; inclusion of a model for scintillation at microwave frequencies in the communication link loss model; and, an updated technological environment.

  8. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, M.S.

    1998-08-18

    A computer system for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments are improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area and sample sequences in another area on a display device. 27 figs.

  9. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, Mark S.

    1999-10-26

    A computer system (1) for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments may be improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area (814) and sample sequences in another area (816) on a display device (3).

  10. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, Mark S.

    1998-08-18

    A computer system for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments are improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area and sample sequences in another area on a display device.

  11. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, Mark S.

    2001-06-05

    A computer system (1) for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments may be improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area (814) and sample sequences in another area (816) on a display device (3).

  12. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, Mark S.; Wang, Chunwei; Jevons, Luis C.; Bernhart, Derek H.; Lipshutz, Robert J.

    2004-05-11

    A computer system for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments are improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area and sample sequences in another area on a display device.

  13. Computer-aided visualization and analysis system for sequence evaluation

    DOEpatents

    Chee, Mark S.

    2003-08-19

    A computer system for analyzing nucleic acid sequences is provided. The computer system is used to perform multiple methods for determining unknown bases by analyzing the fluorescence intensities of hybridized nucleic acid probes. The results of individual experiments may be improved by processing nucleic acid sequences together. Comparative analysis of multiple experiments is also provided by displaying reference sequences in one area and sample sequences in another area on a display device.

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

    SciTech Connect

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

    2014-01-01

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

  15. Do choosing wisely tools meet criteria for patient decision aids? A descriptive analysis of patient materials

    PubMed Central

    Légaré, France; Hébert, Jessica; Goh, Larissa; Lewis, Krystina B; Leiva Portocarrero, Maria Ester; Robitaille, Hubert; Stacey, Dawn

    2016-01-01

    Objectives Choosing Wisely is a remarkable physician-led campaign to reduce unnecessary or harmful health services. Some of the literature identifies Choosing Wisely as a shared decision-making approach. We evaluated the patient materials developed by Choosing Wisely Canada to determine whether they meet the criteria for shared decision-making tools known as patient decision aids. Design Descriptive analysis of all Choosing Wisely Canada patient materials. Data source In May 2015, we selected all Choosing Wisely Canada patient materials from its official website. Main outcomes and measures Four team members independently extracted characteristics of the English materials using the International Patient Decision Aid Standards (IPDAS) modified 16-item minimum criteria for qualifying and certifying patient decision aids. The research team discussed discrepancies between data extractors and reached a consensus. Descriptive analysis was conducted. Results Of the 24 patient materials assessed, 12 were about treatments, 11 were about screening and 1 was about prevention. The median score for patient materials using IPDAS criteria was 10/16 (range: 8–11) for screening topics and 6/12 (range: 6–9) for prevention and treatment topics. Commonly missed criteria were stating the decision (21/24 did not), providing balanced information on option benefits/harms (24/24 did not), citing evidence (24/24 did not) and updating policy (24/24 did not). Out of 24 patient materials, only 2 met the 6 IPDAS criteria to qualify as patient decision aids, and neither of these 2 met the 6 certifying criteria. Conclusions Patient materials developed by Choosing Wisely Canada do not meet the IPDAS minimal qualifying or certifying criteria for patient decision aids. Modifications to the Choosing Wisely Canada patient materials would help to ensure that they qualify as patient decision aids and thus as more effective shared decision-making tools. PMID:27566638

  16. Investigation of computer-aided colonic crypt pattern analysis

    NASA Astrophysics Data System (ADS)

    Qi, Xin; Pan, Yinsheng; Sivak, Michael V., Jr.; Olowe, Kayode; Rollins, Andrew M.

    2007-02-01

    Colorectal cancer is the second leading cause of cancer-related death in the United States. Approximately 50% of these deaths could be prevented by earlier detection through screening. Magnification chromoendoscopy is a technique which utilizes tissue stains applied to the gastrointestinal mucosa and high-magnification endoscopy to better visualize and characterize lesions. Prior studies have shown that shapes of colonic crypts change with disease and show characteristic patterns. Current methods for assessing colonic crypt patterns are somewhat subjective and not standardized. Computerized algorithms could be used to standardize colonic crypt pattern assessment. We have imaged resected colonic mucosa in vitro (N = 70) using methylene blue dye and a surgical microscope to approximately simulate in vivo imaging with magnification chromoendoscopy. We have developed a method of computerized processing to analyze the crypt patterns in the images. The quantitative image analysis consists of three steps. First, the crypts within the region of interest of colonic tissue are semi-automatically segmented using watershed morphological processing. Second, crypt size and shape parameters are extracted from the segmented crypts. Third, each sample is assigned to a category according to the Kudo criteria. The computerized classification is validated by comparison with human classification using the Kudo classification criteria. The computerized colonic crypt pattern analysis algorithm will enable a study of in vivo magnification chromoendoscopy of colonic crypt pattern correlated with risk of colorectal cancer. This study will assess the feasibility of screening and surveillance of the colon using magnification chromoendoscopy.

  17. Computer-aided fiber analysis for crime scene forensics

    NASA Astrophysics Data System (ADS)

    Hildebrandt, Mario; Arndt, Christian; Makrushin, Andrey; Dittmann, Jana

    2012-03-01

    The forensic analysis of fibers is currently completely manual and therefore time consuming. The automation of analysis steps can significantly support forensic experts and reduce the time, required for the investigation. Moreover, a subjective expert belief is extended by objective machine estimation. This work proposes the pattern recognition pipeline containing the digital acquisition of a fiber media, the pre-processing for fiber segmentation, and the extraction of the distinctive characteristics of fibers. Currently, basic geometrical features like width, height, area of optically dominant fibers are investigated. In order to support the automatic classification of fibers, supervised machine learning algorithms are evaluated. The experimental setup includes a car seat and two pieces clothing of a different fabric. As preliminary work, acrylic as synthetic and sheep wool as natural fiber are chosen to be classified. While sitting on the seat, a test person leaves textile fibers. The test aims at automatic distinguishing of clothes through the fiber traces gained from the seat with the help of adhesive tape. The digitalization of fiber samples is provided by a contactless chromatic white light sensor. First test results showed, that two optically very different fibers can be properly assigned to their corresponding fiber type. The best classifier achieves an accuracy of 75 percent correctly classified samples for our suggested features.

  18. Variance Analysis and Comparison in Computer-Aided Design

    NASA Astrophysics Data System (ADS)

    Ullrich, T.; Schiffer, T.; Schinko, C.; Fellner, D. W.

    2011-09-01

    The need to analyze and visualize differences of very similar objects arises in many research areas: mesh compression, scan alignment, nominal/actual value comparison, quality management, and surface reconstruction to name a few. In computer graphics, for example, differences of surfaces are used for analyzing mesh processing algorithms such as mesh compression. They are also used to validate reconstruction and fitting results of laser scanned surfaces. As laser scanning has become very important for the acquisition and preservation of artifacts, scanned representations are used for documentation as well as analysis of ancient objects. Detailed mesh comparisons can reveal smallest changes and damages. These analysis and documentation tasks are needed not only in the context of cultural heritage but also in engineering and manufacturing. Differences of surfaces are analyzed to check the quality of productions. Our contribution to this problem is a workflow, which compares a reference / nominal surface with an actual, laser-scanned data set. The reference surface is a procedural model whose accuracy and systematics describe the semantic properties of an object; whereas the laser-scanned object is a real-world data set without any additional semantic information.

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

    PubMed Central

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

    2016-01-01

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

  20. A review of surface-crack fracture testing. [and failure analysis

    NASA Technical Reports Server (NTRS)

    Orange, T. W.

    1974-01-01

    A brief historical review of surface-crack testing and analysis is given together with some examples of service failures due to surface cracks. The factors which complicate the analysis and interpretation of surface-crack fracture data are discussed. Current efforts to develop consensus recommendations for tensile testing of surface-crack specimens are summarized.

  1. Failure analysis of electronic parts: Laboratory methods. [for destructive and nondestructive testing

    NASA Technical Reports Server (NTRS)

    Anstead, R. J. (Editor); Goldberg, E. (Editor)

    1975-01-01

    Failure analysis test methods are presented for use in analyzing candidate electronic parts and in improving future design reliability. Each test is classified as nondestructive, semidestructive, or destructive. The effects upon applicable part types (i.e. integrated circuit, transitor) are discussed. Methodology is given for performing the following: immersion tests, radio graphic tests, dewpoint tests, gas ambient analysis, cross sectioning, and ultraviolet examination.

  2. A Canonical Correlation Analysis of AIDS Restriction Genes and Metabolic Pathways Identifies Purine Metabolism as a Key Cooperator

    PubMed Central

    Ye, Hanhui; Yuan, Jinjin; Wang, Zhengwu; Huang, Aiqiong; Liu, Xiaolong; Han, Xiao; Chen, Yahong

    2016-01-01

    Human immunodeficiency virus causes a severe disease in humans, referred to as immune deficiency syndrome. Studies on the interaction between host genetic factors and the virus have revealed dozens of genes that impact diverse processes in the AIDS disease. To resolve more genetic factors related to AIDS, a canonical correlation analysis was used to determine the correlation between AIDS restriction and metabolic pathway gene expression. The results show that HIV-1 postentry cellular viral cofactors from AIDS restriction genes are coexpressed in human transcriptome microarray datasets. Further, the purine metabolism pathway comprises novel host factors that are coexpressed with AIDS restriction genes. Using a canonical correlation analysis for expression is a reliable approach to exploring the mechanism underlying AIDS. PMID:27462363

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

    PubMed

    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.

  4. EVALUATION OF SAFETY IN A RADIATION ONCOLOGY SETTING USING FAILURE MODE AND EFFECTS ANALYSIS

    PubMed Central

    Ford, Eric C.; Gaudette, Ray; Myers, Lee; Vanderver, Bruce; Engineer, Lilly; Zellars, Richard; Song, Danny Y.; Wong, John; DeWeese, Theodore L.

    2013-01-01

    Purpose Failure mode and effects analysis (FMEA) is a widely used tool for prospectively evaluating safety and reliability. We report our experiences in applying FMEA in the setting of radiation oncology. Methods and Materials We performed an FMEA analysis for our external beam radiation therapy service, which consisted of the following tasks: (1) create a visual map of the process, (2) identify possible failure modes; assign risk probability numbers (RPN) to each failure mode based on tabulated scores for the severity, frequency of occurrence, and detectability, each on a scale of 1 to 10; and (3) identify improvements that are both feasible and effective. The RPN scores can span a range of 1 to 1000, with higher scores indicating the relative importance of a given failure mode. Results Our process map consisted of 269 different nodes. We identified 127 possible failure modes with RPN scores ranging from 2 to 160. Fifteen of the top-ranked failure modes were considered for process improvements, representing RPN scores of 75 and more. These specific improvement suggestions were incorporated into our practice with a review and implementation by each department team responsible for the process. Conclusions The FMEA technique provides a systematic method for finding vulnerabilities in a process before they result in an error. The FMEA framework can naturally incorporate further quantification and monitoring. A general-use system for incident and near miss reporting would be useful in this regard. PMID:19409731

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

    PubMed

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

    2014-10-01

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

  6. Evaluation of Safety in a Radiation Oncology Setting Using Failure Mode and Effects Analysis

    SciTech Connect

    Ford, Eric C. Gaudette, Ray; Myers, Lee; Vanderver, Bruce; Engineer, Lilly; Zellars, Richard; Song, Danny Y.; Wong, John; DeWeese, Theodore L.

    2009-07-01

    Purpose: Failure mode and effects analysis (FMEA) is a widely used tool for prospectively evaluating safety and reliability. We report our experiences in applying FMEA in the setting of radiation oncology. Methods and Materials: We performed an FMEA analysis for our external beam radiation therapy service, which consisted of the following tasks: (1) create a visual map of the process, (2) identify possible failure modes; assign risk probability numbers (RPN) to each failure mode based on tabulated scores for the severity, frequency of occurrence, and detectability, each on a scale of 1 to 10; and (3) identify improvements that are both feasible and effective. The RPN scores can span a range of 1 to 1000, with higher scores indicating the relative importance of a given failure mode. Results: Our process map consisted of 269 different nodes. We identified 127 possible failure modes with RPN scores ranging from 2 to 160. Fifteen of the top-ranked failure modes were considered for process improvements, representing RPN scores of 75 and more. These specific improvement suggestions were incorporated into our practice with a review and implementation by each department team responsible for the process. Conclusions: The FMEA technique provides a systematic method for finding vulnerabilities in a process before they result in an error. The FMEA framework can naturally incorporate further quantification and monitoring. A general-use system for incident and near miss reporting would be useful in this regard.

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

    PubMed

    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.

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

    SciTech Connect

    Xu, Y; Bhatnagar, J; Bednarz, G; Flickinger, J; Arai, Y; Huq, M Saiful; Vacsulka, J; Monaco, E; Niranjan, A; Lunsford, L Dade; Feng, W

    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

  9. Extracellular space preservation aids the connectomic analysis of neural circuits

    PubMed Central

    Pallotto, Marta; Watkins, Paul V; Fubara, Boma; Singer, Joshua H; Briggman, Kevin L

    2015-01-01

    Dense connectomic mapping of neuronal circuits is limited by the time and effort required to analyze 3D electron microscopy (EM) datasets. Algorithms designed to automate image segmentation suffer from substantial error rates and require significant manual error correction. Any improvement in segmentation error rates would therefore directly reduce the time required to analyze 3D EM data. We explored preserving extracellular space (ECS) during chemical tissue fixation to improve the ability to segment neurites and to identify synaptic contacts. ECS preserved tissue is easier to segment using machine learning algorithms, leading to significantly reduced error rates. In addition, we observed that electrical synapses are readily identified in ECS preserved tissue. Finally, we determined that antibodies penetrate deep into ECS preserved tissue with only minimal permeabilization, thereby enabling correlated light microscopy (LM) and EM studies. We conclude that preservation of ECS benefits multiple aspects of the connectomic analysis of neural circuits. DOI: http://dx.doi.org/10.7554/eLife.08206.001 PMID:26650352

  10. Acoustic emission and acousto-ultrasonic signature analysis of failure mechanisms in carbon fiber reinforced polymer materials

    NASA Astrophysics Data System (ADS)

    Carey, Shawn Allen

    Fiber reinforced polymer composite materials, particularly carbon (CFRPs), are being used for primary structural applications, particularly in the aerospace and naval industries. Advantages of CFRP materials, compared to traditional materials such as steel and aluminum, include: light weight, high strength to weight ratio, corrosion resistance, and long life expectancy. A concern with CFRPs is that despite quality control during fabrication, the material can contain many hidden internal flaws. These flaws in combination with unseen damage due to fatigue and low velocity impact have led to catastrophic failure of structures and components. Therefore a large amount of research has been conducted regarding nondestructive testing (NDT) and structural health monitoring (SHM) of CFRP materials. The principal objective of this research program was to develop methods to characterize failure mechanisms in CFRP materials used by the U.S. Army using acoustic emission (AE) and/or acousto-ultrasonic (AU) data. Failure mechanisms addressed include fiber breakage, matrix cracking, and delamination due to shear between layers. CFRP specimens were fabricated and tested in uniaxial tension to obtain AE and AU data. The specimens were designed with carbon fibers in different orientations to produce the different failure mechanisms. Some specimens were impacted with a blunt indenter prior to testing to simulate low-velocity impact. A signature analysis program was developed to characterize the AE data based on data examination using visual pattern recognition techniques. It was determined that it was important to characterize the AE event , using the location of the event as a parameter, rather than just the AE hit (signal recorded by an AE sensor). A back propagation neural network was also trained based on the results of the signature analysis program. Damage observed on the specimens visually with the aid of a scanning electron microscope agreed with the damage type assigned by the

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

    PubMed

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

    2016-10-01

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

  12. Clinical analysis of HIV/AIDS patients with drug eruption in Yunnan, China

    PubMed Central

    Li, Yu-Ye; Jin, Yong-Mei; He, Li-Ping; Bai, Jin-Song; Liu, Jun; Yu, Min; Chen, Jian-Hua; Wen, Jing; Kuang, Yi-Qun

    2016-01-01

    Drug eruption is the most common clinical presentation in patients with HIV/AIDS. The systemic clinical and risk factors associated with drug eruption remain unknown. A retrospective analysis in HIV/AIDS patients with drug eruption was carried out with demographic data, epidemiological data, clinical characteristics, laboratory data and follow-up data. The risk factors correlated with prognosis were assessed by case control analysis. A total of 134 out of 1817 HIV/AIDS patients (7.4%) presented drug eruptions. The major class of sensitizing drug was HAART drugs (47.7%), followed by antibiotics (47.0%). Nevirapine (39.6%) was the most common sensitizing drug in the HAART regimens. The patients received HAART or had allergic history were prone to develop drug eruption. The alanine aminotransferase, albumin, globulin, creatinine, blood urea nitrogen (BUN), lymphocytes, red blood cells (RBC) and eosinophils of the drug eruption patients were significantly different the control patients. The allergic history, opportunistic infection, viral load, CD4 cell count, high globulin and low albumin were the risk factors correlated with death in HIV/AIDS patients with drug eruption. It is proposed that patients with higher viral loads, higher globulin levels and lower white blood cells (WBC) should be given special attention for the prevention of complications and death. PMID:27796328

  13. Computer-Aided Energy Analysis for Buildings: An Assessment of Its Value for Students of Technology and Architecture.

    ERIC Educational Resources Information Center

    Ridenour, Steven

    1981-01-01

    Demonstrates that computer aided energy analysis improves students' (N=29) comprehension and prediction accuracy of energy consumption in buildings and confirms that a reasonably accurate building energy analysis computer program can be designed for student users. (Author/SK)

  14. BRAF Pyrosequencing Analysis Aided by a Lookup Table

    PubMed Central

    Olson, Matthew T.; Harrington, Colleen; Beierl, Katie; Chen, Guoli; Thiess, Michele; O'Neill, Alan; Taube, Janis M.; Zeiger, Martha A.; Lin, Ming-Tseh; Eshleman, James R.

    2015-01-01

    Objectives BRAF mutations have substantial therapeutic, diagnostic, and prognostic significance, so detecting and specifying them is an important part of the workload of molecular pathology laboratories. Pyrosequencing assays are well suited for this analysis but can produce complex results. Therefore, we introduce a pyrosequencing lookup table based on Pyromaker that assists the user in generating hypotheses for solving complex pyrosequencing results. Methods The lookup table contains all known mutations in the sequenced region and the positions in the dispensation sequence at which changes would occur with those mutations. We demonstrate the lookup table using a homebrew dispensation sequence for BRAF codons 596 to 605 as well as a commercially available kit-based dispensation sequence for codons 599 to 600. Results These results demonstrate that the homebrew dispensation sequence unambiguously identifies all known BRAF mutations in this region, whereas the kit-based dispensation sequence has one unresolvable degeneracy that could be solved with the addition of two injections. Conclusions Using the lookup table and confirmatory virtual pyrogram, we unambiguously solved clinical pyrograms of the complex mutations V600K (c.1798_1799delGTinsAA), V600R (c.1798_1799delGTinsAG), V600D (c.1799_1800delTGinsAT), V600E (c.1799_1800delTGinsAA), and V600_K601delinsE (c.1799_1801delTGA). In addition, we used the approach to hypothesize and confirm a new mutation in human melanoma, V600_K601delinsEI (c.1799_1802delTGAAinsAAAT). PMID:24713734

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

    PubMed Central

    Magnezi, Racheli; Hemi, Asaf; Hemi, Rina

    2016-01-01

    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. PMID:27980440

  16. Failure Analysis of a Complex Learning Framework Incorporating Multi-Modal and Semi-Supervised Learning

    SciTech Connect

    Pullum, Laura L; Symons, Christopher T

    2011-01-01

    Machine learning is used in many applications, from machine vision to speech recognition to decision support systems, and is used to test applications. However, though much has been done to evaluate the performance of machine learning algorithms, little has been done to verify the algorithms or examine their failure modes. Moreover, complex learning frameworks often require stepping beyond black box evaluation to distinguish between errors based on natural limits on learning and errors that arise from mistakes in implementation. We present a conceptual architecture, failure model and taxonomy, and failure modes and effects analysis (FMEA) of a semi-supervised, multi-modal learning system, and provide specific examples from its use in a radiological analysis assistant system. The goal of the research described in this paper is to provide a foundation from which dependability analysis of systems using semi-supervised, multi-modal learning can be conducted. The methods presented provide a first step towards that overall goal.

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

    NASA Astrophysics Data System (ADS)

    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

  18. Evaluation of Progressive Failure Analysis and Modeling of Impact Damage in Composite Pressure Vessels

    NASA Technical Reports Server (NTRS)

    Sanchez, Christopher M.

    2011-01-01

    NASA White Sands Test Facility (WSTF) is leading an evaluation effort in advanced destructive and nondestructive testing of composite pressure vessels and structures. WSTF is using progressive finite element analysis methods for test design and for confirmation of composite pressure vessel performance. Using composite finite element analysis models and failure theories tested in the World-Wide Failure Exercise, WSTF is able to estimate the static strength of composite pressure vessels. Additionally, test and evaluation on composites that have been impact damaged is in progress so that models can be developed to estimate damage tolerance and the degradation in static strength.

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

    NASA Technical Reports Server (NTRS)

    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.

  20. [Failure mechanisms in the transfusion process. Importance of anticipatory operational safety analysis].

    PubMed

    Hergon, E; Crespeau, H; Rouger, P

    1994-01-01

    The methods used for the safety previsional analysis of operations represent an interesting set of tools to follow the so-called transfusion process, defined as all the steps from donors sensitization to recipients follow-up. FMECA (Failure Mode Effects and Criticality Analysis) can be used as a prevention tool, independently of any dysfunction in the process. Of course, it can also be used following a failure, in order to analyse its causes and to apply specific corrections. Operation safety, quality insurance, epidemiologic surveillance and safety monitoring act in synergy. These three aspects of transfusion safety constitute a dynamic system.

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

    SciTech Connect

    Campbell, A.; Tangyunyong, P.

    1999-03-26

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

  2. Failure mechanism analysis of electromigration dominated damage in TiSi2 nanowires

    NASA Astrophysics Data System (ADS)

    Zou, Chen-Xia; Xu, Jun; Zhang, Xin-Zheng; Song, Xue-Feng; Yu, Da-Peng

    2009-06-01

    Electromigration-induced damage has been an important concern in very large scale integrated circuit design for a long time and will be a major road block in the pursuit of nanoelectronics devices and next generation power electronics. In this letter, the failure mechanism analysis on two-terminal TiSi2 nanowire devices was reported. Electromigration dominant mass migration is observed and verified by energy dispersive spectroscopy. The contribution of thermomigration is discussed based on temperature simulation. This work provides useful reference for future devices and the failure analysis on nanostructures.

  3. Consumer preferences for hearing aid attributes: a comparison of rating and conjoint analysis methods.

    PubMed

    Bridges, John F P; Lataille, Angela T; Buttorff, Christine; White, Sharon; Niparko, John K

    2012-03-01

    Low utilization of hearing aids has drawn increased attention to the study of consumer preferences using both simple ratings (e.g., Likert scale) and conjoint analyses, but these two approaches often produce inconsistent results. The study aims to directly compare Likert scales and conjoint analysis in identifying important attributes associated with hearing aids among those with hearing loss. Seven attributes of hearing aids were identified through qualitative research: performance in quiet settings, comfort, feedback, frequency of battery replacement, purchase price, water and sweat resistance, and performance in noisy settings. The preferences of 75 outpatients with hearing loss were measured with both a 5-point Likert scale and with 8 paired-comparison conjoint tasks (the latter being analyzed using OLS [ordinary least squares] and logistic regression). Results were compared by examining implied willingness-to-pay and Pearson's Rho. A total of 56 respondents (75%) provided complete responses. Two thirds of respondents were male, most had sensorineural hearing loss, and most were older than 50; 44% of respondents had never used a hearing aid. Both methods identified improved performance in noisy settings as the most valued attribute. Respondents were twice as likely to buy a hearing aid with better functionality in noisy environments (p < .001), and willingness to pay for this attribute ranged from US$2674 on the Likert to US$9000 in the conjoint analysis. The authors find a high level of concordance between the methods-a result that is in stark contrast with previous research. The authors conclude that their result stems from constraining the levels on the Likert scale.

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

    SciTech Connect

    Wan, Lipeng; Wang, Feiyi; Oral, H. Sarp; Vazhkudai, Sudharshan S.; Cao, Qing

    2014-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

  6. Modern Material Analysis Instruments Add a New Dimension to Materials Characterization and Failure Analysis

    NASA Technical Reports Server (NTRS)

    Panda, Binayak

    2009-01-01

    Modern analytical tools can yield invaluable results during materials characterization and failure analysis. Scanning electron microscopes (SEMs) provide significant analytical capabilities, including angstrom-level resolution. These systems can be equipped with a silicon drift detector (SDD) for very fast yet precise analytical mapping of phases, as well as electron back-scattered diffraction (EBSD) units to map grain orientations, chambers that admit large samples, variable pressure for wet samples, and quantitative analysis software to examine phases. Advanced solid-state electronics have also improved surface and bulk analysis instruments: Secondary ion mass spectroscopy (SIMS) can quantitatively determine and map light elements such as hydrogen, lithium, and boron - with their isotopes. Its high sensitivity detects impurities at parts per billion (ppb) levels. X-ray photo-electron spectroscopy (XPS) can determine oxidation states of elements, as well as identifying polymers and measuring film thicknesses on coated composites. This technique is also known as electron spectroscopy for chemical analysis (ESCA). Scanning Auger electron spectroscopy (SAM) combines surface sensitivity, spatial lateral resolution (10 nm), and depth profiling capabilities to describe elemental compositions of near and below surface regions down to the chemical state of an atom.

  7. Failure analysis of woven and braided fabric reinforced composites

    SciTech Connect

    Naik, R.A.

    1994-09-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

  8. Failure analysis of woven and braided fabric reinforced composites

    NASA Technical Reports Server (NTRS)

    Naik, Rajiv A.

    1994-01-01

    A general purpose micromechanics analysis that discretely models the yarn architecture within the textile repeating unit cell was developed to predict overall, three dimensional, thermal and mechanical properties, damage initiation and progression, and strength. This analytical technique was implemented in a user-friendly, personal computer-based, menu-driven code called Textile Composite Analysis for Design (TEXCAD). TEXCAD was used to analyze plain weave and 2x2, 2-D triaxial braided composites. The calculated tension, compression, and shear strengths correlated well with available test data for both woven and braided composites. Parametric studies were performed on both woven and braided architectures to investigate the effects of parameters such as yarn size, yarn spacing, yarn crimp, braid angle, and overall fiber volume fraction on the strength properties of the textile composite.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

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

    NASA Astrophysics Data System (ADS)

    Simola, Kaisa; Laakso, Kari

    1992-01-01

    Eight years of operating experiences of 104 motor operated closing valves in different safety systems in nuclear power units were analyzed in a systematic way. The qualitative methods used were Failure Mode and Effect Analysis (FMEA) and Maintenance Effects and Criticality Analysis (MECA). These reliability engineering methods are commonly used in the design stage of equipment. The successful application of these methods for analysis and utilization of operating experiences was demonstrated.

  11. An Analysis of the Role of Teachers' Aides in a State Secondary School: Perceptions of Teaching Staff and Teachers' Aides

    ERIC Educational Resources Information Center

    Gibson, Dianne; Paatsch, Louise; Toe, Dianne

    2016-01-01

    In Victoria, Australia, one of the major roles of the teachers' aide (TA) is to assist students with disabilities to access their education. Researchers have identified the inconsistencies in defining the roles of the TA, in a variety of settings, by TAs, teachers, parents, and other research participants. Four main themes that have been…

  12. Faith-based aid, globalisation and the humanitarian frontline: an analysis of Western-based Muslim aid organisations.

    PubMed

    De Cordier, Bruno

    2009-10-01

    This paper focuses on the emergence and modus operandi of Muslim faith-based aid organisations from the West, particularly those from the United Kingdom. Through case studies of Islamic Relief Worldwide and Muslim Hands, it examines the actual and potential added value generated by these humanitarian players in Muslim-majority contexts at times when aid actors from or associated with the West are being perceived by some as instrumental to the political agendas of Western powers, or are being confronted with the consequences thereof. The study analyses Muslim faith-based aid organisations' transnational networks, their implementing partnerships with local faith-based non-governmental organisations (NGOs), and their security position within and their access to insecure contexts, drawing on field examples and opinion from Central Asia, Iraq and Pakistan. It thereby argues that there is ground for an expansion of the role of Muslim aid actors, because of the existence of social and political realities in the field that cannot be always effectively tackled by the dominant international development approaches.

  13. Compendium of Post-Failure Analysis Techniques for Composite Materials.

    DTIC Science & Technology

    1987-01-01

    Thermal Aging 3-18 Glass Transition Temperature Determination - 3-37 TMA Penetration Test Setup 3-19 Glass Transition Temperature Determination - 3-37 TMA...peak distortions and spectral interferences may occur. Figure 3-17 (ref 3) illustrates DRIFTS spectra of a composite before and after thermal aging ...where increasing oxidation with aging is observed. Note the increased absorbence levels at 1654 to 1696 nm. 3.1.4 Degree of Cure Analysis The degree of

  14. Failure Analysis of High Pressure Test Facility Control Valves

    DTIC Science & Technology

    2013-10-01

    larger than the axial load applied to the stem by the actuator in the closed valve position), so we decided that no further buckling analysis was...caused the stem to bend. There are only two modes by which the stem could have bent in the manner it did: buckling and/or a cantilever load...load; however, we have clearly demonstrated on other valves (much to our embarrassment) that it is entirely possible to buckle the stem by over

  15. Stability and failure analysis of steering tie-rod

    NASA Astrophysics Data System (ADS)

    Jiang, GongFeng; Zhang, YiLiang; Xu, XueDong; Ding, DaWei

    2008-11-01

    A new car in operation of only 8,000 km, because of malfunction, resulting in lost control and rammed into the edge of the road, and then the basic vehicle scrapped. According to the investigation of the site, it was found that the tie-rod of the car had been broken. For the subjective analysis of the accident and identifying the true causes of rupture of the tierod, a series of studies, from the angle of theory to experiment on the bended broken tie-rod, were conducted. The mechanical model was established; the stability of the defective tie-rod was simulated based on ANSYS software. Meanwhile, the process of the accident was simulated considering the effect of destabilization of different vehicle speed and direction of the impact. Simultaneously, macro graphic test, chemical composition analysis, microstructure analysis and SEM analysis of the fracture were implemented. The results showed that: 1) the toughness of the tie-rod is at a normal level, but there is some previous flaws. One quarter of the fracture surface has been cracked before the accident. However, there is no relationship between the flaw and this incident. The direct cause is the dynamic instability leading to the large deformation of impact loading. 2) The declining safety factor of the tie-rod greatly due to the previous flaws; the result of numerical simulation shows that previous flaw is the vital factor of structure instability, on the basis of the comparison of critical loads of the accident tie-rod and normal. The critical load can decrease by 51.3% when the initial defect increases 19.54% on the cross-sectional area, which meets the Theory of Koiter.

  16. Failure Analysis of a Helicopter External Fuel-Tank Pylon

    NASA Technical Reports Server (NTRS)

    Newman, John A.; Piascik, Robert S.; Lindenberg, Richard A.

    2002-01-01

    An eight-inch-long (0.2 m) crack was found in an external fuel-tank pylon of a U.S. Coast Guard HH-60 helicopter. The damaged pylon was removed from service and destructively examined at NASA Langley Research Center (LaRC) to determine the cause of the crack. Results of the analysis revealed that crack initiation occurred at corrosion pits in a fastener hole and crack propagation was a result of cyclic loading.

  17. Failure Analysis of Epoxy-Lined Asbestos-Cement Pipe.

    DTIC Science & Technology

    1981-12-01

    hardness, and stability when exposed samples were thoroughly dried at 212OF (100 0C) to acidic, alkaline, and neutral liquid submersion. overnight in...more pliable. Residual stresses usually cause Infra- Red Analysis deformation of the plastic. which releives the stresses. Detailed analyses were...conducted using a Fourier Transform Infra- Red Spectrometer (FTIR). This The degree or extent of swelling depends on a method allows precise, well-defined

  18. Trustworthy patient decision aids: a qualitative analysis addressing the risk of competing interests

    PubMed Central

    Elwyn, Glyn; Dannenberg, Michelle; Blaine, Arianna; Poddar, Urbashi; Durand, Marie-Anne

    2016-01-01

    Objective Our aim in this study was to examine the competing interest policies and procedures of organisations who develop and maintain patient decision aids. Design Descriptive and thematic analysis of data collected from a cross-sectional survey of patient decision aid developer's competing interest policies and disclosure forms. Results We contacted 25 organisations likely to meet the inclusion criteria. 12 eligible organisations provided data. 11 organisations did not reply and 2 declined to participate. Most patient decision aid developers recognise the need to consider the issue of competing interests. Assessment processes vary widely and, for the most part, are insufficiently robust to minimise the risk of competing interests. Only half of the 12 organisations had competing interest policies. Some considered disclosure to be sufficient, while others imposed differing levels of exclusion. Conclusions Patient decision aid developers do not have a consistent approach to managing competing interests. Some have developed policies and procedures, while others pay no attention to the issue. As is the case for clinical practice guidelines, increasing attention will need to be given to how the competing interests of contributors of evidence-based publications may influence materials, especially if they are designed for patient use. PMID:27612542

  19. On the convergence of nanotechnology and Big Data analysis for computer-aided diagnosis.

    PubMed

    Rodrigues, Jose F; Paulovich, Fernando V; de Oliveira, Maria Cf; de Oliveira, Osvaldo N

    2016-04-01

    An overview is provided of the challenges involved in building computer-aided diagnosis systems capable of precise medical diagnostics based on integration and interpretation of data from different sources and formats. The availability of massive amounts of data and computational methods associated with the Big Data paradigm has brought hope that such systems may soon be available in routine clinical practices, which is not the case today. We focus on visual and machine learning analysis of medical data acquired with varied nanotech-based techniques and on methods for Big Data infrastructure. Because diagnosis is essentially a classification task, we address the machine learning techniques with supervised and unsupervised classification, making a critical assessment of the progress already made in the medical field and the prospects for the near future. We also advocate that successful computer-aided diagnosis requires a merge of methods and concepts from nanotechnology and Big Data analysis.

  20. Computer aided morphometric analysis of oral leukoplakia and oral squamous cell carcinoma.

    PubMed

    Gupta, K; Gupta, J; Miglani, R

    2016-01-01

    We compared the changes in the cells in the basal layer of normal mucosa, oral leukoplakia with dysplasia and different grades of oral squamous cell carcinoma (OSCC) using computer aided image analysis of tissue sections. We investigated three morphometric parameters: nuclear area (NA), cell area (CA) and their ratio (NA:CA). NA and NA:CA ratio showed a statistically significant increase from dysplasia to increasing grades of OSCC. Nuclear size was useful for differentiating normal tissue, potentially malignant leukoplakia and OSCC.

  1. The Dark Side of EDX Tomography: Modeling Detector Shadowing to Aid 3D Elemental Signal Analysis.

    PubMed

    Yeoh, Catriona S M; Rossouw, David; Saghi, Zineb; Burdet, Pierre; Leary, Rowan K; Midgley, Paul A

    2015-06-01

    A simple model is proposed to account for the loss of collected X-ray signal by the shadowing of X-ray detectors in the scanning transmission electron microscope. The model is intended to aid the analysis of three-dimensional elemental data sets acquired using energy-dispersive X-ray tomography methods where shadow-free specimen holders are unsuitable or unavailable. The model also provides a useful measure of the detection system geometry.

  2. Failure Analysis of Main Flame Deflector Nelson Studs

    NASA Technical Reports Server (NTRS)

    Long, Victoria

    2009-01-01

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

  3. Predictive Failure of Cylindrical Coatings Using Weibull Analysis

    NASA Technical Reports Server (NTRS)

    Vlcek, Brian L.; Hendricks, Robert C.; Zaretsky, Erwin V.

    2002-01-01

    Rotating, coated wiping rollers used in a high-speed printing application failed primarily from fatigue. Two coating materials were evaluated: a hard, cross-linked, plasticized polyvinyl chloride (PVC) and a softer, plasticized PVC. A total of 447 tests was conducted with these coatings in a production facility. The data were evaluated using Weibull analysis. The softer coating produced more than twice the life of the harder cross-linked coating and reduced the wiper replacement rate by two-thirds, resulting in minimum production interruption.

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

    PubMed

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

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

    SciTech Connect

    Dana L. Kelly

    2008-02-01

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

  8. Predictive failure analysis: planning for the worst so that it never happens!

    PubMed

    Hipple, Jack

    2008-01-01

    This article reviews an alternative approach to failure analysis involving a deliberate saboteurial approach rather than a checklist approach to disaster and emergency preparedness. This process is in the form of an algorithm that is easily applied to any planning situation.

  9. Failure modes and effects analysis of a coal-slurry preheater

    SciTech Connect

    Mitchell, H.A.; Parsly, L.F.; Smith, A.N.

    1981-09-01

    The Fossil Energy performance assurance program is concerned with the application of reliability, safety, and quality assurance techniques in the design and operation of the pilot plants and demonstration plants that exist or are being planned as part of the US Department of Energy fossil energy conversion programs. This report involves the application of one technique, failure modes and effects analysis (FMEA), on the safety and reliability analysis of the coal slurry preheater, a critical component in a typical coal direct liquefaction plant. The analysis identifies 55 potential failure modes. Fourteen of these events, if they should occur, would result in losses of sufficient magnitude to require special consideration in the design or operating phase to assure control of risk at an acceptable level. The report concludes that the FMEA could be a valuable tool in the identification of critical components for coal conversion systems. For maximum effect, FMEA needs to be used during the initial design phase. Its principal value is to determine high-risk failure modes, which could have unacceptable impacts on system safety and reliability/availability. The usefulness of FMEA will be improved if it is supplemented by the development of a failure data base; this data base could also be of value in selected cases as input to a more detaled technique such as fault-tree analysis.

  10. The Efficacy of Hospitalization of Nonorganic Failure-to-Thrive Children: A Meta-Analysis.

    ERIC Educational Resources Information Center

    Fryer, George E., Jr.

    1988-01-01

    A meta-analysis of eight studies, involving 192 subjects, was performed to ascertain the efficacy of hospitalization of children with nonorganic failure to thrive. Hospitalization was found to approximately double the probability of catch-up physical growth for the children, but psychosocial development was only modestly hastened by…

  11. Analysis of High Power IGBT Short Circuit Failures

    SciTech Connect

    Pappas, G.

    2005-02-11

    The Next Linear Collider (NLC) accelerator proposal at SLAC requires a highly efficient and reliable, low cost, pulsed-power modulator to drive the klystrons. A solid-state induction modulator has been developed at SLAC to power the klystrons; this modulator uses commercial high voltage and high current Insulated Gate Bipolar Transistor (IGBT) modules. Testing of these IGBT modules under pulsed conditions was very successful; however, the IGBTs failed when tests were performed into a low inductance short circuit. The internal electrical connections of a commercial IGBT module have been analyzed to extract self and mutual partial inductances for the main current paths as well as for the gate structure. The IGBT module, together with the partial inductances, has been modeled using PSpice. Predictions for electrical paths that carry the highest current correlate with the sites of failed die under short circuit tests. A similar analysis has been carried out for a SLAC proposal for an IGBT module layout. This paper discusses the mathematical model of the IGBT module geometry and presents simulation results.

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

    PubMed

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

    2016-11-01

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

  13. Application of Failure Mode and Effects Analysis to Intraoperative Radiation Therapy Using Mobile Electron Linear Accelerators

    SciTech Connect

    Ciocca, Mario; Cantone, Marie-Claire; Veronese, Ivan; Cattani, Federica; Pedroli, Guido; Molinelli, Silvia; Vitolo, Viviana; Orecchia, Roberto

    2012-02-01

    Purpose: Failure mode and effects analysis (FMEA) represents a prospective approach for risk assessment. A multidisciplinary working group of the Italian Association for Medical Physics applied FMEA to electron beam intraoperative radiation therapy (IORT) delivered using mobile linear accelerators, aiming at preventing accidental exposures to the patient. Methods and Materials: FMEA was applied to the IORT process, for the stages of the treatment delivery and verification, 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, based on the product of three parameters (severity, frequency of occurrence and detectability, each ranging from 1 to 10); 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. Results: Twenty-four subprocesses were identified. Ten potential failure modes were found and scored, in terms of RPN, in the range of 42-216. The most critical failure modes consisted of internal shield misalignment, wrong Monitor Unit calculation and incorrect data entry at treatment console. Potential causes of failure included shield displacement, human errors, such as underestimation of CTV extension, mainly because of lack of adequate training and time pressures, failure in the communication between operators, and machine malfunctioning. The main effects of failure were represented by CTV underdose, wrong dose distribution and/or delivery, unintended normal tissue irradiation. As additional safety measures, the utilization of a dedicated staff for IORT, double-checking of MU calculation and data entry and finally implementation of in vivo dosimetry were suggested. Conclusions: FMEA appeared as a useful tool for prospective evaluation of patient safety in radiotherapy. The

  14. Dam failure analysis for the Lago de Matrullas Dam, Orocovis, Puerto Rico

    USGS Publications Warehouse

    Torres-Sierra, Heriberto; Gómez-Fragoso, Julieta

    2015-01-01

    Results from the simulated dam failure of the Lago de Matrullas Dam using the HEC–RAS model for the 6- and 24-hour PMP events showed peak discharges at the dam of 3,149.33 and 3,604.70 m3/s, respectively. Dam failure during the 100-year-recurrence, 24-hour rainfall event resulted in a peak discharge of 2,103.12 m3/s directly downstream from the dam. Dam failure under sunny day conditions produced a peak discharge of 1,695.91 m3/s at the dam assuming the antecedent lake level was at the morning-glory spillway invert elevation. Flood-inundation maps prepared as part of the study depict the flood extent and provide valuable information for preparing an Emergency Action Plan. Results of the failure analysis indicate that a failure of the Lago de Matrullas Dam could cause flooding to many of the inhabited areas along stream banks from the Lago de Matrullas Dam to the mouth of the Río Grande de Manatí. Among the areas most affected are the low-lying regions in the vicinity of the towns of Ciales, Manatí, and Barceloneta. The delineation of the flood boundaries near the town of Barceloneta considered the effects of a levee constructed during 2000 at Barceloneta in the flood plain of the Río Grande de Manatí to provide protection against flooding to the near-by low-lying populated areas. The results showed overtopping can be expected in the aforementioned levee during 6- and 24-hour probable-maximum-precipitation dam failure scenarios. No overtopping of the levee was simulated, however, during dam failure scenarios under the 100-year recurrence, 24-hour rainfall event or sunny day conditions.

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

    SciTech Connect

    Sawant, Amit; Dieterich, Sonja; Svatos, Michelle; Keall, Paul

    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

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

    PubMed Central

    Sawant, Amit; Dieterich, Sonja; Svatos, Michelle; Keall, Paul

    2010-01-01

    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 ∼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 ∼35 min, while that taken for comprehensive testing was ∼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 efficient

  17. Differentiation of Benign Pigmented Skin Lesions with the Aid of Computer Image Analysis: A Novel Approach

    PubMed Central

    Choi, Jae Woo; Park, Young Woon; Byun, Sang Young

    2013-01-01

    Background The differential diagnosis of common pigmented skin lesions is important in cosmetic dermatology. The computer aided image analysis would be a potent ancillary diagnostic tool when patients are hesitant to undergo a skin biopsy. Objective We investigated the numerical parameters discriminating each pigmented skin lesion from another with statistical significance. Methods For each of the five magnified digital images containing clinically diagnosed nevus, lentigo and seborrheic keratosis, a total of 23 parameters describing the morphological, color, texture and topological features were calculated with the aid of a self-developed image analysis software. A novel concept of concentricity was proposed, which represents how closely the color segmentation resembles a concentric circle. Results Morphologically, seborrheic keratosis was bigger and spikier than nevus and lentigo. The color histogram revealed that nevus was the darkest and had the widest variation in tone. In the aspect of texture, the surface of the nevus showed the highest contrast and correlation. Finally, the color segmented pattern of the nevus and lentigo was far more concentric than that of seborrheic keratosis. Conclusion We found that the subtle distinctions between nevus, lentigo and seborrheic keratosis, which are likely to be unrecognized by ocular inspection, are well emphasized and detected with the aid of software. PMID:24003278

  18. Nucleic acid tool enzymes-aided signal amplification strategy for biochemical analysis: status and challenges.

    PubMed

    Qing, Taiping; He, Dinggeng; He, Xiaoxiao; Wang, Kemin; Xu, Fengzhou; Wen, Li; Shangguan, Jingfang; Mao, Zhengui; Lei, Yanli

    2016-04-01

    Owing to their highly efficient catalytic effects and substrate specificity, the nucleic acid tool enzymes are applied as 'nano-tools' for manipulating different nucleic acid substrates both in the test-tube and in living organisms. In addition to the function as molecular scissors and molecular glue in genetic engineering, the application of nucleic acid tool enzymes in biochemical analysis has also been extensively developed in the past few decades. Used as amplifying labels for biorecognition events, the nucleic acid tool enzymes are mainly applied in nucleic acids amplification sensing, as well as the amplification sensing of biorelated variations of nucleic acids. With the introduction of aptamers, which can bind different target molecules, the nucleic acid tool enzymes-aided signal amplification strategies can also be used to sense non-nucleic targets (e.g., ions, small molecules, proteins, and cells). This review describes and discusses the amplification strategies of nucleic acid tool enzymes-aided biosensors for biochemical analysis applications. Various analytes, including nucleic acids, ions, small molecules, proteins, and cells, are reviewed briefly. This work also addresses the future trends and outlooks for signal amplification in nucleic acid tool enzymes-aided biosensors.

  19. Towards the development of multilevel-multiagent diagnostic aids. [Root-cause analysis

    SciTech Connect

    Stratton, R.C.; Jarrell, D.B.

    1991-09-01

    Presented here is our methodology for developing automated aids for diagnosing faults in complex systems based on research at the Pacific Northwest Laboratory (PNL) for the US Department of Energy and the US Nuclear Regulatory Commission. We have designed these aids as multilevel-multiagent diagnostic aids based on principles that should be generally applicable to any complex system. Our research in fault diagnosis at PNL grew out of our work in root-cause analysis (RCA). Our approach consists of those major activities which we categorize as (1) determining knowledge requirements, (2) constructing models, and (3) developing the requirements for representation schemes. We group knowledge for fault diagnosis into two broad groups: cognitive task and process-system knowledge. Our research indicates that a useful representation scheme can be developed employing function and object hierarchies, task required inference, and task specified reasoning control. Formal modeling of the reasoning task determines the required task inference and control. This research has focused on the use of the representation scheme for fault diagnosis. However, preliminary analysis indicates that this same scheme may be useful in automating control tasks. The next phase of this research is to develop a prototype. The prototype system has been specified and we are presently developing knowledge models of the components and system. 19 refs., 15 figs., 10 tabs.

  20. Use of computer aided drafting for analysis and control of posture in manual work.

    PubMed

    Ulin, S S; Armstrong, T J; Radwin, R G

    1990-06-01

    Computer aided design (CAD) in conjunction with digitised anthropometric manikins can be used for analysis and control of stressful work postures, one of the most frequently cited occupational risk factors of upper extremity cumulative trauma disorders. This paper describes the use of macros for manipulating manikins and workstation components and for designing the workplace. AutoCAD, a popular computer aided design software package, was used to demonstrate the feasibility of these concepts. Specifically, macros are used for drawing work equipment using parametric designs, manipulating manikins and analysing jobs. In comparing the macros to the use of primitive CAD commands, the macros not only decrease the amount of time needed to create workstation components, but they also make the task easier for the user and decrease the risk of errors. Despite the limitation of anthropometric data and manikins, CAD is an effective method for identifying postural stresses and redesigning the workstation to control the identified stresses.

  1. Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

    NASA Technical Reports Server (NTRS)

    Lahoti, G. D.; Akgerman, N.; Altan, T.

    1978-01-01

    Mild steel (AISI 1018) was selected as model cold rolling material and Ti-6A1-4V and Inconel 718 were selected as typical hot rolling and cold rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape rolling process were developed. These models utilized the upper bound and the slab methods of analysis, and were capable of predicting the lateral spread, roll separating force, roll torque, and local stresses, strains and strain rates. This computer-aided design system was also capable of simulating the actual rolling process, and thereby designing the roll pass schedule in rolling of an airfoil or a similar shape.

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  3. Statistical analysis of bivariate failure time data with Marshall-Olkin Weibull models.

    PubMed

    Li, Yang; Sun, Jianguo; Song, Shuguang

    2012-06-01

    This paper discusses parametric analysis of bivariate failure time data, which often occur in medical studies among others. For this, as in the case of univariate failure time data, exponential and Weibull models are probably the most commonly used ones. However, it is surprising that there seem no general estimation procedures available for fitting the bivariate Weibull model to bivariate right-censored failure time data except some methods for special situations. We present and investigate two general but simple estimation procedures, one being a graphical approach and the other being a marginal approach, for the problem. An extensive simulation study is conducted to assess the performances of the proposed approaches and shows that they work well for practical situations. An illustrative example is provided.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Jingkui; Zhang, Liaojun

    2014-06-01

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

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

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

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

  6. Vertical modelling: Analysis of competing risks data with missing causes of failure.

    PubMed

    Nicolaie, M A; van Houwelingen, H C; Putter, H

    2015-12-01

    We propose vertical modelling as a natural approach to the problem of analysis of competing risks data when failure types are missing for some individuals. Under a natural missing-at-random assumption for these missing failure types, we use the observed data likelihood to estimate its parameters and show that the all-cause hazard and the relative hazards appearing in vertical modelling are indeed key quantities of this likelihood. This fact has practical implications in that it suggests vertical modelling as a simple and attractive method of analysis in competing risks with missing causes of failure; all individuals are used in estimating the all-cause hazard and only those with non-missing cause of failure for relative hazards. The relative hazards also appear in a multiple imputation approach to the same problem proposed by Lu and Tsiatis and in the EM algorithm. We compare the vertical modelling approach with the method of Goetghebeur and Ryan for a breast cancer data set, highlighting the different aspects they contribute to the data analysis.

  7. An analysis of fiber-matrix interface failure stresses for a range of ply stress states

    NASA Technical Reports Server (NTRS)

    Crews, J. H.; Naik, R. A.; Lubowinski, S. J.

    1993-01-01

    A graphite/bismaleimide laminate was prepared without the usual fiber treatment and was tested over a wide range of stress states to measure its ply cracking strength. These tests were conducted using off-axis flexure specimens and produced fiber-matrix interface failure data over a correspondingly wide range of interface stress states. The absence of fiber treatment, weakened the fiber-matrix interfaces and allowed these tests to be conducted at load levels that did not yield the matrix. An elastic micromechanics computer code was used to calculate the fiber-matrix interface stresses at failure. Two different fiber-array models (square and diamond) were used in these calculations to analyze the effects of fiber arrangement as well as stress state on the critical interface stresses at failure. This study showed that both fiber-array models were needed to analyze interface stresses over the range of stress states. A linear equation provided a close fit to these critical stress combinations and, thereby, provided a fiber-matrix interface failure criterion. These results suggest that prediction procedures for laminate ply cracking can be based on micromechanics stress analyses and appropriate fiber-matrix interface failure criteria. However, typical structural laminates may require elastoplastic stress analysis procedures that account for matrix yielding, especially for shear-dominated ply stress states.

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

    NASA Astrophysics Data System (ADS)

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

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

  9. Performance improvement through proactive risk assessment: Using failure modes and effects analysis

    PubMed Central

    Yarmohammadian, Mohammad Hossein; Abadi, Tahereh Naseri Boori; Tofighi, Shahram; Esfahani, Sekine Saghaeiannejad

    2014-01-01

    Introduction: Cognizance of any error-prone professional activities has a great impact on the continuity of professional organizations in the competitive atmosphere, particularly in health care industry where every second has critical value in patients’ life saving. Considering invaluable functions of medical record department — as legal document and continuity of health care — “failure mode and effects analysis (FMEA)” utilized to identify the ways a process can fail, and how it can be made safer. Materials and Methods: The structured approach involved assembling a team of experts, employing a trained facilitator, introducing the rating scales and process during team orientation and collectively scoring failure modes. The probability of the failure-effect combination was related to the frequency of occurrence, potential severity, and likelihood of detection before causing any harm to the staff or patients. Frequency, severity and detectability were each given a score from 1 to 10. Risk priority numbers were calculated. Results: In total 56 failure modes were identified and in subsets of Medical Record Department including admission unit dividing emergency, outpatient and inpatient classes, statististic, health data organizing and data processing and Medical Coding units. Although most failure modes were classified as a high risk group, limited resources were, as an impediment to implement recommended actions at the same time. Conclusion: Proactive risk assessment methods, such as FMEA enable health care administrators to identify where and what safeguards are needed to protect against a bad outcome even when an error does occur. PMID:25013821

  10. Ply-level failure analysis of a graphite/epoxy laminate under bearing-bypass loading

    NASA Technical Reports Server (NTRS)

    Naik, R. A.; Crews, J. H., Jr.

    1988-01-01

    A combined experimental and analytical study was conducted to investigate and predict the failure modes of a graphite/epoxy laminate subjected to combined bearing and bypass loading. Tests were conducted in a test machine that allowed the bearing-bypass load ratio to be controlled while a single-fastener coupon was loaded to failure in either tension or compression. Onset and ultimate failure modes and strengths were determined for each test case. The damage-onset modes were studied in detail by sectioning and micrographing the damaged specimens. A two-dimensional, finite-element analysis was conducted to determine lamina strains around the bolt hole. Damage onset consisted of matrix cracks, delamination, and fiber failures. Stiffness loss appeared to be caused by fiber failures rather than by matrix cracking and delamination. An unusual offset-compression mode was observed for compressive bearing-bypass laoding in which the specimen failed across its width along a line offset from the hole. The computed lamina strains in the fiber direction were used in a combined analytical and experimental approach to predict bearing-bypass diagrams for damage onset from a few simple tests.

  11. Ply-level failure analysis of a graphite/epoxy laminate under bearing-bypass loading

    NASA Technical Reports Server (NTRS)

    Naik, R. A.; Crews, J. H., Jr.

    1990-01-01

    A combined experimental and analytical study was conducted to investigate and predict the failure modes of a graphite/epoxy laminate subjected to combined bearing and bypass loading. Tests were conducted in a test machine that allowed the bearing-bypass load ratio to be controlled while a single-fastener coupon was loaded to failure in either tension or compression. Onset and ultimate failure modes and strengths were determined for each test case. The damage-onset modes were studied in detail by sectioning and micrographing the damaged specimens. A two-dimensional, finite-element analysis was conducted to determine lamina strains around the bolt hole. Damage onset consisted of matrix cracks, delamination, and fiber failures. Stiffness loss appeared to be caused by fiber failures rather than by matrix cracking and delamination. An unusual offset-compression mode was observed for compressive bearing-bypass loading in which the specimen failed across its width along a line offset from the hole. The computed lamina strains in the fiber direction were used in a combined analytical and experimental approach to predict bearing-bypass diagrams for damage onset from a few simple tests.

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

    NASA Astrophysics Data System (ADS)

    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

  13. Mathematical and Numerical Analysis of Model Equations on Interactions of the HIV/AIDS Virus and the Immune System

    NASA Astrophysics Data System (ADS)

    Parumasur, N.; Willie, R.

    2008-09-01

    We consider a simple HIV/AIDs finite dimensional mathematical model on interactions of the blood cells, the HIV/AIDs virus and the immune system for consistence of the equations to the real biomedical situation that they model. A better understanding to a cure solution to the illness modeled by the finite dimensional equations is given. This is accomplished through rigorous mathematical analysis and is reinforced by numerical analysis of models developed for real life cases.

  14. Anticipating risk for human subjects participating in clinical research: application of Failure Mode and Effects Analysis.

    PubMed

    Cody, Robert J

    2006-03-01

    Failure Mode and Effects Analysis (FMEA) is a method applied in various industries to anticipate and mitigate risk. This methodology can be more systematically applied to the protection of human subjects in research. The purpose of FMEA is simple: prevent problems before they occur. By applying FMEA process analysis to the elements of a specific research protocol, the failure severity, occurrence, and detection rates can be estimated for calculation of a "risk priority number" (RPN). Methods can then be identified to reduce the RPN to levels where the risk/benefit ratio favors human subject benefit, to a greater magnitude than existed in the pre-analysis risk profile. At the very least, the approach provides a checklist of issues that can be individualized for specific research protocols or human subject populations.

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

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2006-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Arnold, Steven M.

    2007-01-01

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

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

    PubMed

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

    2010-08-20

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

  18. An analysis of molten-corium-induced failure of drain pipes in BWR Mark 2 containments

    SciTech Connect

    Taleyarkhan, R.P. ); Podowski, M.Z. )

    1991-01-01

    This study has focused on mechanistic simulation and analysis of potential failure modes for inpedestal drywell drain pipes in the Limerick boiling water reactor (BWR) Mark 2 containment. Physical phenomena related to surface tension breakdown, heatup, melting, ablation, crust formation and failure, and core material relocation into drain pipes with simultaneous melting of pipe walls were modeled and analyzed. The results of analysis have been used to assess the possibility of drain pipe failure and the resultant loss of pressure-suppression capability. Estimates have been made for the timing and amount of molten corium released to the wetwell. The study has revealed that significantly different melt progression sequences can result depending upon the failure characteristics of the frozen metallic crust which forms over the drain cover during the initial stages of debris pour. Another important result is that it can take several days for the molten fuel to ablate the frozen metallic debris layer -- if the frozen layer has cooled below 1100 K before fuel attack. 10 refs., 3 figs., 4 tabs.

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

    NASA Astrophysics Data System (ADS)

    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.

  20. Grieving experiences amongst adolescents orphaned by AIDS: Analysis from event history calendars.

    PubMed

    Thupayagale-Tshweneagae, Gloria

    2012-09-07

    Mental health is an essential component of adolescent health and wellbeing. Mental health practitioners assess adolescents' mental health status to identify possible issues that may lead to mental health problems. However, very few of the tools used to assess the mental health status of adolescents include assessment for grieving and coping patterns. The current tools used for assessing an individual's mental health are lengthy and not comprehensive. The purpose of this study was to assess grieving patterns of adolescents orphaned by AIDS and to appraise the usefulness of an event history calendar as an assessment tool for identifying grieving experiences, in order to guide and support these adolescents through the grieving process. One hundred and two adolescents aged 14-18 years, who had been orphaned by AIDS, completed an event history calendar, reviewed it with the researcher and reported their perceptions of it. Thematic analysis of the event history calendar content revealed that it is an effective, time-efficient, adolescent-friendly tool that facilitated identification and discussion of the orphaned adolescents' grieving patterns. Crying, isolation, silence and violent outbursts were the main grieving patterns reported by adolescents orphaned by AIDS. The researcher recommends use of the event history calendar for identification of orphaned adolescents' grieving experiences. Early identification would enable mental health practitioners to support them in order to prevent the occurrence of mental illness due to maladaptive grieving.

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

    SciTech Connect

    Korsah, Kofi; Wood, Richard Thomas

    2015-06-01

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

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

    PubMed Central

    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”,

  3. Common cause failure analysis of the rodded scram system of the Arkansas Nuclear One-Unit 1 Plant

    SciTech Connect

    Montague, D.F.; Campbell, D.J.; Flanagan, G.F.

    1986-10-01

    This study demonstrates the use of a formal method for common cause failure analysis in a reliability analysis of the Arkansas Nuclear One - Unit 1 rodded scram system. The scram system failure of interest is loss of capability of the system to shut the reactor down when required. The results of this analysis support the ATWS program sponsored by the US Nuclear Regulatory Commission. The methods used in this analysis support the NRC's Risk Methods Integration and Evaluation Program (RMIEP).

  4. Analysis of dental materials as an aid to identification in aircraft accidents.

    PubMed

    Wilson, G S; Cruickshanks-Boyd, D W

    1982-04-01

    The failure to achieve positive identification of aircrew following an aircraft accident need not prevent a full autopsy and toxicological examination to ascertain possible medical factors involved in the accident. Energy-dispersive electron microprobe analysis provides morphological, qualitative, and accurate quantitative analysis of the composition of dental amalgam. Wet chemical analysis can be used to determine the elemental composition of crowns, bridges and partial dentures. Unfilled resin can be analyzed by infrared spectroscopy. Detailed analysis of filled composite restorative resins has not yet been achieved in the "as-set" condition to permit discrimination between manufacturers' products. Future work will involve filler studies and pyrolysis of the composite resins by thermogravimetric analysis to determine percentage weight loss when the sample examined is subjected to a controlled heating regime. With these available techniques, corroborative evidence achieved from the scientific study of materials can augment standard forensic dental results to obtain a positive identification.

  5. Analysis of dental materials as an aid to identification in aircraft accidents

    SciTech Connect

    Wilson, G.S.; Cruickshanks-Boyd, D.W.

    1982-04-01

    The failure to achieve positive identification of aircrew following an aircraft accident need not prevent a full autopsy and toxicological examination to ascertain possible medical factors involved in the accident. Energy-dispersive electron microprobe analysis provides morphological, qualitative, and accurate quantitative analysis of the composition of dental amalgam. Wet chemical analysis can be used to determine the elemental composition of crowns, bridges and partial dentures. Unfilled resin can be analyzed by infrared spectroscopy. Detailed analysis of filled composite restorative resins has not yet been achieved in the as-set condition to permit discrimination between manufacturers' products. Future work will involve filler studies and pyrolysis of the composite resins by thermogravimetric analysis to determine percentage weight loss when the sample examined is subjected to a controlled heating regime. With these available techniques, corroborative evidence achieved from the scientific study of materials can augment standard forensic dental results to obtain a positive identification.

  6. Flexibility analysis of biomacromolecules with application to computer-aided drug design.

    PubMed

    Fulle, Simone; Gohlke, Holger

    2012-01-01

    Flexibility characteristics of biomacromolecules can be efficiently determined down to the atomic level by a graph-theoretical technique as implemented in the FIRST (Floppy Inclusion and Rigid Substructure Topology) and ProFlex software packages. The method has been successfully applied to a series of protein and nucleic acid structures. Here, we describe practical guidelines for setting up and performing a flexibility analysis, discuss current bottlenecks of the approach, and provide sample applications as to how this technique can support computer-aided drug design approaches.

  7. Computer-Aided Analysis of Patents for Product Technology Maturity Forecasting

    NASA Astrophysics Data System (ADS)

    Liang, Yanhong; Gan, Dequan; Guo, Yingchun; Zhang, Peng

    Product technology maturity foresting is vital for any enterprises to hold the chance for innovation and keep competitive for a long term. The Theory of Invention Problem Solving (TRIZ) is acknowledged both as a systematic methodology for innovation and a powerful tool for technology forecasting. Based on TRIZ, the state -of-the-art on the technology maturity of product and the limits of application are discussed. With the application of text mining and patent analysis technologies, this paper proposes a computer-aided approach for product technology maturity forecasting. It can overcome the shortcomings of the current methods.

  8. Strengthening capacity for AIDS vaccine research: analysis of the Pfizer Global Health Fellows Program and the International AIDS Vaccine Initiative

    PubMed Central

    2013-01-01

    Background Industry partnerships can help leverage resources to advance HIV/AIDS vaccine research, service delivery, and policy advocacy goals. This often involves capacity building for international and local non-governmental organizations (NGOs). International volunteering is increasingly being used as a capacity building strategy, yet little is known about how corporate volunteers help to improve performance of NGOs in the fight against HIV/AIDS. Methods This case study helps to extend our understanding by analyzing how the Pfizer Global Health Fellows (GHF) program helped develop capacity of the International AIDS Vaccine Initiative (IAVI), looking specifically at Fellowship activities in South Africa, Kenya, and Uganda. From 2005–2009, 8 Pfizer GHF worked with IAVI and local research centers to strengthen capacity to conduct and monitor vaccine trials to meet international standards and expand trial activities. Data collection for the case study included review of Fellow job descriptions, online journals, evaluation reports, and interviews with Fellows and IAVI staff. Qualitative methods were used to analyze factors which influenced the process and outcomes of capacity strengthening. Results Fellows filled critical short-term expert staffing needs at IAVI as well as providing technical assistance and staff development activities. Capacity building included assistance in establishing operating procedures for the start-up period of research centers; training staff in Good Clinical Practice (GCP); developing monitoring capacity (staff and systems) to assure that centers are audit-ready at all times; and strategic planning for data management systems. Factors key to the success of volunteering partnerships included similarities in mission between the corporate and NGO partners, expertise and experience of Fellows, and attitudes of partner organization staff. Conclusion By developing standard operating procedures, ensuring that monitoring and regulatory

  9. Ivabradine in the treatment of systolic heart failure - A systematic review and meta-analysis

    PubMed Central

    Anantha Narayanan, Mahesh; Reddy, Yogesh N V; Baskaran, Janani; Deshmukh, Abhishek; Benditt, David G; Raveendran, Ganesh

    2017-01-01

    AIM To perform a systematic-review and meta-analysis to compare outcomes of ivabradine combined with beta-blocker to beta-blocker alone in heart failure with reduced ejection fraction (HFrEF). METHODS We searched PubMed, Cochrane, EMBASE, CINAHL and Web of Science for trials comparing ivabradine + beta-blocker to beta-blocker alone in HFrEF. We performed a systematic-review and meta-analysis of published literature. Primary end-point was combined end point of cardiac death and hospitalization for heart failure. RESULTS Six studies with 17671 patients were included. Mean follow-up was 8.7 ± 7.9 mo. Combined end-point of heart failure readmission and cardiovascular death was better in ivabradine + beta-blocker group compared to beta-blocker alone (RR: 0.93, 95%CI: 0.79-1.09, P = 0.354). Mean difference (MD) in heart rate was higher in the ivabradine + beta-blocker group (MD: 6.14, 95%CI: 3.80-8.48, P < 0.001). There was no difference in all cause mortality (RR: 0.98, 95%CI: 0.89-1.07, P = 0.609), cardiovascular mortality (RR: 0.99, 95%CI: 0.86-1.15, P = 0.908) or heart failure hospitalization (RR: 0.87, 95%CI: 0.68-1.11, P = 0.271). CONCLUSION From the available clinical trials, ivabradine + beta-blocker resulted in a significantly greater reduction in HR coupled with improvement in combined end-point of heart failure readmission and cardiovascular death but with no improvement in all cause or cardiovascular mortality. Given the limited evidence, further randomized controlled trials are essential before widespread clinical application of ivabradine + beta-blocker is advocated for HFrEF. PMID:28289533

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

    PubMed Central

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

    2016-01-01

    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

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

    NASA Technical Reports Server (NTRS)

    Knight, Norman F., Jr.

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  14. Model OA Wind Turbine Generator FEMA (Failure Modes and Effects Analysis)

    SciTech Connect

    Klein, W.E. . Plum Brook Station); Lalli, V.R. . Lewis Research Center)

    1989-10-01

    This report presents the results of Failure Modes and Effects Analysis (FMEA) conducted for the Wind Turbine Generators. 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. 2 refs., 3 figs.

  15. Analysis of the STS-126 Flow Control Valve Structural-Acoustic Coupling Failure

    NASA Technical Reports Server (NTRS)

    Jones, Trevor M.; Larko, Jeffrey M.; McNelis, Mark E.

    2010-01-01

    During the Space Transportation System mission STS-126, one of the main engine's flow control valves incurred an unexpected failure. A section of the valve broke off during liftoff. It is theorized that an acoustic mode of the flowing fuel, coupled with a structural mode of the valve, causing a high cycle fatigue failure. This report documents the analysis efforts conducted in an attempt to verify this theory. Hand calculations, computational fluid dynamics, and finite element methods are all implemented and analyses are performed using steady-state methods in addition to transient analysis methods. The conclusion of the analyses is that there is a critical acoustic mode that aligns with a structural mode of the valve

  16. Digital Instrumentation and Control Failure Events Derivation and Analysis by Frame-Based Technique

    SciTech Connect

    Hui-Wen Huang; Chunkuan Shih; Swu Yih; Yen-Chang Tzeng; Ming-Huei Chen

    2006-07-01

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

  17. Failure Analysis of Cracked FS-85 Tubing and ASTAR-811C End Caps

    SciTech Connect

    ME Petrichek

    2006-02-09

    Failure analyses were performed on cracked FS-85 tubing and ASTAR-811C and caps which had been fabricated as components of biaxial creep specimens meant to support materials testing for the NR Space program. During the failure analyses of cracked FS-85 tubing, it was determined that the failure potentially could be due to two effects: possible copper contamination from the EDM (electro-discharge machined) recast layer and/or an insufficient solution anneal. to prevent similar failures in the future, a more formal analysis should be done after each processing step to ensure the quality of the material before further processing. During machining of the ASTAR-811FC rod to form end caps for biaxial creep specimens, linear defects were observed along the center portion of the end caps. These defects were only found in material that was processed from the top portion of the ingot. The linear defects were attributed to a probable residual ingot pipe that was not removed from the ingot. During the subsequent processing of the ingot to rod, the processing temperatures were not high enough to allow self healing of the ingot's residual pipe defect. To prevent this from occurring in the future, it is necessary to ensure that complete removal of the as-melted ingot pipe is verified by suitable non-destructive evaluation (NDE).

  18. Failure Mode and Effect Analysis for Delivery of Lung Stereotactic Body Radiation Therapy

    SciTech Connect

    Perks, Julian R.; Stanic, Sinisa; Stern, Robin L.; Henk, Barbara; Nelson, Marsha S.; Harse, Rick D.; Mathai, Mathew; Purdy, James A.; Valicenti, Richard K.; Siefkin, Allan D.; Chen, Allen M.

    2012-07-15

    Purpose: To improve the quality and safety of our practice of stereotactic body radiation therapy (SBRT), we analyzed the process following the failure mode and effects analysis (FMEA) method. Methods: The FMEA was performed by a multidisciplinary team. For each step in the SBRT delivery process, a potential failure occurrence was derived and three factors were assessed: the probability of each occurrence, the severity if the event occurs, and the probability of detection by the treatment team. A rank of 1 to 10 was assigned to each factor, and then the multiplied ranks yielded the relative risks (risk priority numbers). The failure modes with the highest risk priority numbers were then considered to implement process improvement measures. Results: A total of 28 occurrences were derived, of which nine events scored with significantly high risk priority numbers. The risk priority numbers of the highest ranked events ranged from 20 to 80. These included transcription errors of the stereotactic coordinates and machine failures. Conclusion: Several areas of our SBRT delivery were reconsidered in terms of process improvement, and safety measures, including treatment checklists and a surgical time-out, were added for our practice of gantry-based image-guided SBRT. This study serves as a guide for other users of SBRT to perform FMEA of their own practice.

  19. Cost Based Failure Modes and Effects Analysis (FMEA) for Systems of Accelerator Magnets.

    SciTech Connect

    Spencer, Cherrill M

    2003-06-02

    The proposed Next Linear Collider (NLC) has a proposed 85% overall availability goal, the availability specifications for all its 7200 magnets and their 6167 power supplies are 97.5% each. Thus all of the electromagnets and their power supplies must be highly reliable or quickly repairable. Improved reliability or repairability comes at a higher cost. We have developed a set of analysis procedures for magnet designers to use as they decide how much effort to exert, i.e. how much money to spend, to improve the reliability of a particular style of magnet. We show these procedures being applied to a standard SLAC electromagnet design in order to make it reliable enough to meet the NLC availability specs. First, empirical data from SLAC's accelerator failure database plus design experience are used to calculate MTBF for failure modes identified through a FMEA. Availability for one particular magnet can be calculated. Next, labor and material costs to repair magnet failures are used in a Monte Carlo simulation to calculate the total cost of all failures over a 30-year lifetime. Opportunity costs are included. Engineers choose from amongst various designs by comparing lifecycle costs.

  20. Failure analysis of Mark IA lithium/iron sulfide battery. [Two 20-kWh modules

    SciTech Connect

    Kolba, V M; Battles, J E; Geller, J D; Gentry, K

    1980-10-01

    The Mark IA lithium/iron sulfide electric-vehicle battery, which consisted of two 20-kWh modules containing 60 cells each, was fabricated by Eagle-Picher Industries, Inc. and delivered to ANL for testing in May 1979. During startup heating prior to electrical testing, a short circuit developed in one of the modules, which resulted in a progressive failure of the cells. The other module, which was alongside and connected in series, was unaffected by the failure. The initial indication of difficulty was a small drop in the voltage of several cells, followed by short circuits in the balance of the cells and localized temperatures above 1000/sup 0/C. A team consisting of ANL and Eagle-Picher personnel conducted a detailed failure analysis as the failed module was disassembled. The other module was also examined for purposes of comparison. The general conclusion was that the short circuit was initiated by electrolyte leakage and resulting corrosion in the nearby region which formed metallic bridges between cells and the cell tray, or arcing between cells and the cell tray through the butt joints in the electrical insulation. The above two mechanisms were also believed to be responsible for the failure propagation. 66 figures, 11 tables.

  1. 2500 KW Ship Service Turbine Generator Casing Welded Inconel Plug Failure and Repair Analysis

    DTIC Science & Technology

    2012-06-01

    2500 KW SHIP SERVICE TURBINE GENERATOR CASING WELDED INCONEL PLUG FAILURE AND REPAIR ANALYSIS John S. Shields, P.E. US Navy NSWCCD... Inconel X750) should have received post weld heat treatment (PWHT) to avoid embrittlement and the subsequent cracking of the HAZ. If PWHT was not...to be accomplished, an alloy such as Inconel 600 should have been selected. It is noted that PWHT risks warping the casing and cannot be performed

  2. Robust Multivariate Evaluation and Failure Prediction of Inhomogeneous Solids Based on Inverse Analysis

    DTIC Science & Technology

    2005-12-31

    Measurements of elastic-plastic anisotropic properties of thermally sprayed coatings using nano-indenters and inverse analysis technique...Proceedings of International Thermal Spray Conference. T. Nakamura and Z. Wang (2003), ‘Dynamic Failure Behavior of Elastic-Plastic Graded Materials...Materials, IMRE, Singapore, January 2006. ‘Nonlinear Properties in Plasma Sprayed Coatings and Relation to Process/Materials’, Consortium on Thermal Spray

  3. Equipment qualification research: test program and failure analysis of Class 1E solenoid valves

    SciTech Connect

    Paulson, D.V.; Shook, T.A.; Bacanskas, V.P.; Carfagno, S.P.

    1983-11-01

    This report documents the results of an equipment qualification research test program performed on ASCO solenoid valves. The valves were subjected to accelerated aging which included 50 Mrd of gamma radiation aging and accelerated thermal aging at 268/sup 0/F (131/sup 0/C). All valves performed satisfactorily during the seismic test. Of the seven valves exposed to the LOCA/MSLB simulation, only a metal-seated valve functioned properly throughout without leakage. At the conclusion of the post-LOCA functional testing, a failure analysis was undertaken to determine the failure mode(s) for each valve. The failure analysis included electrical testing of solenoid coils, controlled disassembly of valves, macro- and microscopic examination of internal parts, Shore A durometer testing of elastomeric components, and mass spectrometer analysis of several components. It was concluded that (1) the use of nitrogen to pressurize the valves during thermal aging severely inhibited the aging process since the majority of EPDM components were blanketed in nitrogen, and (2) operational cycling at the elevated thermal aging temperature may have produced stresses not representative of in-service use.

  4. Novel failure analysis techniques using photon probing with a scanning optical microscope

    SciTech Connect

    Cole, E.I. Jr.; Soden, J.M.; Rife, J.L.; Barton, D.L.; Henderson, C.L.

    1993-12-31

    Three new failure analysis techniques for integrated circuits (ICs) have been developed using localized photon probing with a scanning optical microscope (SOM). The first two are light-induced voltage alteration (LIVA) imaging techniques that (1) localize open-circuited and damaged junctions and (2) image transistor logic states. The third technique uses the SOM to control logic states optically from the IC backside. LIVA images are produced by monitoring the voltage fluctuations of a constant current power supply as a laser beam is scanned over the IC. High selectivity for localizing defects has been demonstrated using the LIVA approach. Logic state mapping results, similar to previous work using biased optical beam induced current (OBIC) and laser probing approaches have also been produced using LIVA. Application of the two LIVA based techniques to backside failure analysis has been demonstrated using an infrared laser source. Optical logic state control is based upon earlier work examining transistor response to photon injection. The physics of each method and their applications for failure analysis are described.

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

    SciTech Connect

    Boring, Ronald Laurids

    2014-10-01

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

  6. Failure analysis of adhesively bonded composite joint: an elasto-plastic approach

    NASA Astrophysics Data System (ADS)

    Pradhan, S. C.; Kishore, N. N.; Iyengar, N. G. R.

    1993-09-01

    Joints are important load transferring members in large assembled structures. In joining similar and dissimilar materials, the use of adhesives offers many advantages when compared to other conventional methods. Most commonly used adhesives are the polymers, which exhibit nonlinear behavior. Finite element analysis with paired nodes along the crack path is employed to predict the crack initiation and growth leading to failure. The bond strength is predicted by investigating the possibility of propagation of a crack at the interface of adherend and adhesive. Paired nodes are opened in a sequence, modelling the crack growth. The adhesive is treated to be elasto-plastic for its response. Effect of the parameters such as, stacking sequences in composite adherend, crack growth locations, bond length, bond thicknesses and adhesive stiffnesses on the failure load is studied. The growth of plastic zone as the crack propagates is also examined. On the basis of this study optimal geometrical and material parameters are suggested. The elasto-plastic analysis predicts higher failure loads as compared to linear elastic analysis. The computed bond strength assuming elastic behavior for the adhesive shows satisfactory comparison with experimental results.

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

    NASA Technical Reports Server (NTRS)

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

    2006-01-01

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

  8. Performance and sensitivity analysis of the generalized likelihood ratio method for failure detection. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Bueno, R. A.

    1977-01-01

    Results of the generalized likelihood ratio (GLR) technique for the detection of failures in aircraft application are presented, and its relationship to the properties of the Kalman-Bucy filter is examined. Under the assumption that the system is perfectly modeled, the detectability and distinguishability of four failure types are investigated by means of analysis and simulations. Detection of failures is found satisfactory, but problems in identifying correctly the mode of a failure may arise. These issues are closely examined as well as the sensitivity of GLR to modeling errors. The advantages and disadvantages of this technique are discussed, and various modifications are suggested to reduce its limitations in performance and computational complexity.

  9. Time-to-Event Analysis of Individual Variables Associated with Nursing Students' Academic Failure: A Longitudinal Study

    ERIC Educational Resources Information Center

    Dante, Angelo; Fabris, Stefano; Palese, Alvisa

    2013-01-01

    Empirical studies and conceptual frameworks presented in the extant literature offer a static imagining of academic failure. Time-to-event analysis, which captures the dynamism of individual factors, as when they determine the failure to properly tailor timely strategies, impose longitudinal studies which are still lacking within the field. The…

  10. Fatigue analysis of computer-aided design/computer-aided manufacturing resin-based composite vs. lithium disilicate glass-ceramic.

    PubMed

    Ankyu, Shuhei; Nakamura, Keisuke; Harada, Akio; Hong, Guang; Kanno, Taro; Niwano, Yoshimi; Örtengren, Ulf; Egusa, Hiroshi

    2016-08-01

    Resin-based composite molar crowns made by computer-aided design/computer-aided manufacturing (CAD/CAM) systems have been proposed as an inexpensive alternative to metal-ceramic or all-ceramic crowns. However, there is a lack of scientific information regarding fatigue resistance. This study aimed to analyze the fatigue behavior of CAD/CAM resin-based composite compared with lithium disilicate glass-ceramic. One-hundred and sixty bar-shaped specimens were fabricated using resin-based composite blocks [Lava Ultimate (LU); 3M/ESPE] and lithium disilicate glass-ceramic [IPS e.max press (EMP); Ivoclar/Vivadent]. The specimens were divided into four groups: no treatment (NT); thermal cycling (TC); mechanical cycling (MC); and thermal cycling followed by mechanical cycling (TCMC). Thermal cycling was performed by alternate immersion in water baths of 5°C and 55°C for 5 × 10(4) cycles. Mechanical cycling was performed in a three-point bending test, with a maximum load of 40 N, for 1.2 × 10(6) cycles. In addition, LU and EMP molar crowns were fabricated and subjected to fatigue treatments followed by load-to-failure testing. The flexural strength of LU was not severely reduced by the fatigue treatments. The fatigue treatments did not significantly affect the fracture resistance of LU molar crowns. The results demonstrate the potential of clinical application of CAD/CAM-generated resin-based composite molar crowns in terms of fatigue resistance.

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

    PubMed

    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.

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

    SciTech Connect

    Hirabayashi, Masatoshi; Scheeres, Daniel J.

    2015-01-01

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

  13. Molecular cytogenetic analysis of Xq critical regions in premature ovarian failure

    PubMed Central

    2013-01-01

    Background One of the frequent reasons for unsuccessful conception is premature ovarian failure/primary ovarian insufficiency (POF/POI) that is defined as the loss of functional follicles below the age of 40 years. Among the genetic causes the most common one involves the X chromosome, as in Turner syndrome, partial X deletion and X-autosome translocations. Here we report a case of a 27-year-old female patient referred to genetic counselling because of premature ovarian failure. The aim of this case study to perform molecular genetic and cytogenetic analyses in order to identify the exact genetic background of the pathogenic phenotype. Results For premature ovarian failure disease diagnostics we performed the Fragile mental retardation 1 gene analysis using Southern blot technique and Repeat Primed PCR in order to identify the relationship between the Fragile mental retardation 1 gene premutation status and the premature ovarion failure disease. At this early onset, the premature ovarian failure affected patient we detected one normal allele of Fragile mental retardation 1 gene and we couldn’t verify the methylated allele, therefore we performed the cytogenetic analyses using G-banding and fluorescent in situ hybridization methods and a high resolution molecular cytogenetic method, the array comparative genomic hybridization technique. For this patient applying the G-banding, we identified a large deletion on the X chromosome at the critical region (ChrX q21.31-q28) which is associated with the premature ovarian failure phenotype. In order to detect the exact breakpoints, we used a special cytogenetic array ISCA plus CGH array and we verified a 67.355 Mb size loss at the critical region which include total 795 genes. Conclusions We conclude for this case study that the karyotyping is definitely helpful in the evaluation of premature ovarian failure patients, to identify the non submicroscopic chromosomal rearrangement, and using the array CGH technique we can

  14. Probability of Failure Analysis Standards and Guidelines for Expendable Launch Vehicles

    NASA Astrophysics Data System (ADS)

    Wilde, Paul D.; Morse, Elisabeth L.; Rosati, Paul; Cather, Corey

    2013-09-01

    Recognizing the central importance of probability of failure estimates to ensuring public safety for launches, the Federal Aviation Administration (FAA), Office of Commercial Space Transportation (AST), the National Aeronautics and Space Administration (NASA), and U.S. Air Force (USAF), through the Common Standards Working Group (CSWG), developed a guide for conducting valid probability of failure (POF) analyses for expendable launch vehicles (ELV), with an emphasis on POF analysis for new ELVs. A probability of failure analysis for an ELV produces estimates of the likelihood of occurrence of potentially hazardous events, which are critical inputs to launch risk analysis of debris, toxic, or explosive hazards. This guide is intended to document a framework for POF analyses commonly accepted in the US, and should be useful to anyone who performs or evaluates launch risk analyses for new ELVs. The CSWG guidelines provide performance standards and definitions of key terms, and are being revised to address allocation to flight times and vehicle response modes. The POF performance standard allows a launch operator to employ alternative, potentially innovative methodologies so long as the results satisfy the performance standard. Current POF analysis practice at US ranges includes multiple methodologies described in the guidelines as accepted methods, but not necessarily the only methods available to demonstrate compliance with the performance standard. The guidelines include illustrative examples for each POF analysis method, which are intended to illustrate an acceptable level of fidelity for ELV POF analyses used to ensure public safety. The focus is on providing guiding principles rather than "recipe lists." Independent reviews of these guidelines were performed to assess their logic, completeness, accuracy, self- consistency, consistency with risk analysis practices, use of available information, and ease of applicability. The independent reviews confirmed the

  15. Heart Failure

    MedlinePlus

    ... version of this page please turn Javascript on. Heart Failure What is Heart Failure? In heart failure, the heart cannot pump enough ... failure often experience tiredness and shortness of breath. Heart Failure is Serious Heart failure is a serious and ...

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

    SciTech Connect

    Errichello, R.; Muller, J.

    2012-02-01

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

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

    SciTech Connect

    Howe, J

    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.

  18. Heart Failure in an Infant With Pierre Robin Sequence: Is There a Diagnostic Test to Aid in Treatment Planning and Monitoring?

    PubMed

    Biskup, Nataliya; Francis, Stacey H

    2015-11-01

    This case report describes an infant with Pierre Robin sequence who was managed conservatively until he presented at 4 months of age with right-sided heart failure. This rare clinical presentation displays the physiologic response to chronic respiratory obstruction and the acid-base disturbances, which become evident on metabolic panel and blood gas. We suggest that these tests can be added to the workup, especially in conservatively managed infants, to help predict which infants may fail conservative treatment and to avoid the rare complication of heart failure in infants with Pierre Robin sequence.

  19. Hearing Aids

    MedlinePlus

    ... Health Info » Hearing, Ear Infections, and Deafness Hearing Aids On this page: What is a hearing aid? ... the ear through a speaker. How can hearing aids help? Hearing aids are primarily useful in improving ...

  20. An application of computer aided requirements analysis to a real time deep space system

    NASA Technical Reports Server (NTRS)

    Farny, A. M.; Morris, R. V.; Hartsough, C.; Callender, E. D.; Teichroew, D.; Chikofsky, E.

    1981-01-01

    The entire procedure of incorporating the requirements and goals of a space flight project into integrated, time ordered sequences of spacecraft commands, is called the uplink process. The Uplink Process Control Task (UPCT) was created to examine the uplink process and determine ways to improve it. The Problem Statement Language/Problem Statement Analyzer (PSL/PSA) designed to assist the designer/analyst/engineer in the preparation of specifications of an information system is used as a supporting tool to aid in the analysis. Attention is given to a definition of the uplink process, the definition of PSL/PSA, the construction of a PSA database, the value of analysis to the study of the uplink process, and the PSL/PSA lessons learned.

  1. Perception and visualization of human posture information for computer-aided ergonomic analysis.

    PubMed

    Liu, Y; Zhang, X; Chaffin, D

    1997-08-01

    This article reports three experiments that examined the effects of photographic method, computerized visualization scheme, and posture complexity on posture perception and specification for computer-aided ergonomic analysis. The subjects were presented with photographs of working postures, and were required to manipulate human forms generated by an ergonomics software program to match the postures in the photographs. The first experiment showed a clear advantage of using a three-dimensional (3-D) human form graphic with two photographs when complex, asymmetric postures were analysed. However, the use of a 3-D human graphic display and two photographs jeopardized the subjects' posture specification performance when simple, symmetric postures were analysed. The results of the second and the third experiment demonstrated the importance of achieving congruency between photographic and computer display perspectives in improving posture specification performance. Implications for ergonomic job analysis and ergonomics software design are discussed.

  2. FBI fingerprint identification automation study: AIDS 3 evaluation report. Volume 6: Environmental analysis

    NASA Technical Reports Server (NTRS)

    Mulhall, B. D. L.

    1980-01-01

    The results of the analysis of the external environment of the FBI Fingerprint Identification Division are presented. Possible trends in the future environment of the Division that may have an effect on the work load were projected to determine if future work load will lie within the capability range of the proposed new system, AIDS 3. Two working models of the environment were developed, the internal and external model, and from these scenarios the projection of possible future work load volume and mixture was developed. Possible drivers of work load change were identified and assessed for upper and lower bounds of effects. Data used for the study were derived from historical information, analysis of the current situation and from interviews with various agencies who are users of or stakeholders in the present system.

  3. High-precision image aided inertial navigation with known features: observability analysis and performance evaluation.

    PubMed

    Jiang, Weiping; Wang, Li; Niu, Xiaoji; Zhang, Quan; Zhang, Hui; Tang, Min; Hu, Xiangyun

    2014-10-17

    A high-precision image-aided inertial navigation system (INS) is proposed as an alternative to the carrier-phase-based differential Global Navigation Satellite Systems (CDGNSSs) when satellite-based navigation systems are unavailable. In this paper, the image/INS integrated algorithm is modeled by a tightly-coupled iterative extended Kalman filter (IEKF). Tightly-coupled integration ensures that the integrated system is reliable, even if few known feature points (i.e., less than three) are observed in the images. A new global observability analysis of this tightly-coupled integration is presented to guarantee that the system is observable under the necessary conditions. The analysis conclusions were verified by simulations and field tests. The field tests also indicate that high-precision position (centimeter-level) and attitude (half-degree-level)-integrated solutions can be achieved in a global reference.

  4. Compression failure of fibrous laminated composites in the presence of stress gradients : experiment and analysis

    NASA Astrophysics Data System (ADS)

    Waas, Anthony M.

    . Subsequent to the 0?-ply failure, extensive delamination cracking is observed with increasing load. The through thickness location of these delaminations is found to depend on the position of the 0? plies.The delaminated portions spread to the undamaged areas of the laminate by a combination of delamination buckling and growth, the buckling further enhancing the growth. When the delaminated area reaches a critical size, about 75-100% of the hole radius in extent, an accelerated growth rate of the delaminated portions is observed. The culmination of this last event is the complete loss of flexural stiffness of each of the delaminated portions leading to catastrophic failure of the plate. The levels of applied load and the rate at which these events occur depend on the plate stacking sequence.A simple mechanical model is presented for the microbuckling problem. This model addresses the buckling instability of a semi-infinte layered half-plane alternatingly stacked with fibers and matrix, loaded parallel to the surface of the half-plane. The fibers are modelled using Bernoulli-Navier beam theory, and the matrix is assumed to be a linearly elastic foundation. The predicted buckling strains are found to overestimate the experimental result. However, the dependence of the buckling strain on parameters such as the fiber volume fraction, ratio of Youngs moduli of the constituents and Poisson's ratio of the matrix are obtained from the analysis. It is seen that a high fiber volume fraction, increased matrix stiffness, and perfect bonding between fiber and matrix are desirable properties for increasing the compressive strength.

  5. Low-Energy Defibrillation Failure Correction is Possible Through Nonlinear Analysis of Spatiotemporal Arrhythmia Data

    NASA Astrophysics Data System (ADS)

    Simonotto, Jennifer; Furman, Michael; Beaver, Thomas; Spano, Mark; Kavanagh, Katherine; Iden, Jason; Hu, Gang; Ditto, William

    2004-03-01

    Explanted Porcine hearts were Langendorff-perfused, administered a voltage-sensitive fluorescent dye (Di-4-ANEPPS) and illuminated with a ND:Yag laser (532 nm); the change in fluorescence resulting from electrical activity on the heart surface was recorded with an 80 x 80 pixel CCD camera at 1000 frames per second. The heart was put into fibrillation with rapid ventricular pacing and shocks were administered close to the defibrillation threshold. Defibrillation failure data was analyzed using synchronization, space-time volume plots and recurrence quantification. Preliminary spatiotemporal synchronization results reveal a short window of time ( 1 second) after defibrillation failure in which the disordered electrical activity becomes ordered; this ordered period occurs 4-5 seconds after the defibrillation shock. Recurrence analysis of a single time series confirmed these results, thus opening the avenue for dynamic defibrillators that can detect an optimal window for cardioversion.

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

    NASA Technical Reports Server (NTRS)

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

    1996-01-01

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

  7. Abrasive Wear Failure Analysis of Tungsten Carbide Hard facing on Carbon Steel Blade

    NASA Astrophysics Data System (ADS)

    Tobi, A. L. Mohd; Kamdi, Z.; Ismail, M. I.; Nagentrau, M.; Roslan, L. N. H.; Mohamad, Z.; Omar, A. S.; Latif, N. Abdul

    2017-01-01

    This study investigate the abrasive wear failure of tungsten carbide hardfacing on continuous digester (CD) blade (carbon steel) in an environment of sulphuric acid and ilmenite ore mixture. Comparison being made on the hardness, thickness and microstructural of the hardfacing between unworn and 3 months old worn blade on few locations around the blade. The cross sections of the blade revealed non-uniform coverage of the hardfacing on the blade for both worn and unworn blade. The edge of the blade has the least amount of hardfacing thickness which with time acts as the point of failure during the wear process. The hardness obtained from both the unworn and worn samples are around 25% lower from the hardfacing electrode manufacturer’s hardness specification. Microstructural micrograph analysis of the hardfacing revealed non uniform size carbide with non-uniform distributed of carbide in the hardfacing layer.

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

    PubMed

    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.

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

    NASA Technical Reports Server (NTRS)

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

    2013-01-01

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

  10. Analysis for organic residues from aids to polymerization used to make plastics intended for food contact.

    PubMed

    Fordham, P J; Gramshaw, J W; Castle, L

    2001-05-01

    Polymers intended for food contact use have been analysed for organic residues which could be attributed to a range of substances employed as polymerization aids (e.g. initiators and catalysts). A wide range of polymers was extracted with solvents and the extracts analysed by gas chromatography mass spectrometry (GC-MS). The overwhelming majority of substances identified were not derived from aids to polymerization but were oligomers, additives and adventitious contaminants. However, a small number of substances were identified as initiator residues. These included tetramethylsuccinonitrile (TMSN) which was observed in two polymers and it derived from recombination of two azobisisobutyronitrile (AIBN) initiator radicals. Methyl benzoate, benzoic acid, biphenyl and phenyl benzoate were detected in one poly(methyl methacrylate) sample and in two polyvinylchlorides and they are thought to be derived from benzoyl peroxide initiator. TMSN was subsequently targeted for analysis of poly-(methyl methacrylate) plastics using proton nuclear magnetic resonance spectrometry (1H-NMR) and GC-MS. NMR detected the presence of cyanoisopropyl radical residues in the plastic at 470-3400 mg/kg whereas GC-MS detected TMSN at only 65-540 mg/kg in the samples. It is concluded that the bulk of cyanoisopropyl residues detected by NMR were either polymer-bound or were the products of side-reactions of the initiator radical. The migration of TMSN itself into the food simulants 3% aqueous acetic acid, 15% aqueous ethanol, and olive oil, at 40 degrees C for 10 days, was measured using GC-MS. Migration was very low with < 1 microg/kg released from a finished article (a drinking straw) and < 5 microg/kg from resin pellets. The overall conclusions from this work are that organic residues from aids to polymerization are generally found at reassuringly low levels in plastics intended for food contact and their potential for migration to foods is correspondingly low.

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

    USGS Publications Warehouse

    Gómez-Fragoso, Julieta; Heriberto Torres-Sierra,

    2016-08-09

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

  12. Extensive risk analysis of mechanical failure for an epiphyseal hip prothesis: a combined numerical-experimental approach.

    PubMed

    Martelli, S; Taddei, F; Cristofolini, L; Gill, H S; Viceconti, M

    2011-02-01

    There has been recent renewed interest in proximal femur epiphyseal replacement as an alternative to conventional total hip replacement. In many branches of engineering, risk analysis has proved to be an efficient tool for avoiding premature failures of innovative devices. An extensive risk analysis procedure has been developed for epiphyseal hip prostheses and the predictions of this method have been compared to the known clinical outcomes of a well-established contemporary design, namely hip resurfacing devices. Clinical scenarios leading to revision (i.e. loosening, neck fracture and failure of the prosthetic component) were associated with potential failure modes (i.e. overload, fatigue, wear, fibrotic tissue differentiation and bone remodelling). Driving parameters of the corresponding failure mode were identified together with their safe thresholds. For each failure mode, a failure criterion was identified and studied under the most relevant physiological loading conditions. All failure modes were investigated with the most suitable investigation tool, either numerical or experimental. Results showed a low risk for each failure scenario either in the immediate postoperative period or in the long term. These findings are in agreement with those reported by the majority of clinical studies for correctly implanted devices. Although further work is needed to confirm the predictions of this method, it was concluded that the proposed risk analysis procedure has the potential to increase the efficacy of preclinical validation protocols for new epiphyseal replacement devices.

  13. Composite laminate failure parameter optimization through four-point flexure experimentation and analysis

    SciTech Connect

    Nelson, Stacy; English, Shawn; Briggs, Timothy

    2016-05-06

    Fiber-reinforced composite materials offer light-weight solutions to many structural challenges. In the development of high-performance composite structures, a thorough understanding is required of the composite materials themselves as well as methods for the analysis and failure prediction of the relevant composite structures. However, the mechanical properties required for the complete constitutive definition of a composite material can be difficult to determine through experimentation. Therefore, efficient methods are necessary that can be used to determine which properties are relevant to the analysis of a specific structure and to establish a structure's response to a material parameter that can only be defined through estimation. The objectives of this paper deal with demonstrating the potential value of sensitivity and uncertainty quantification techniques during the failure analysis of loaded composite structures; and the proposed methods are applied to the simulation of the four-point flexural characterization of a carbon fiber composite material. Utilizing a recently implemented, phenomenological orthotropic material model that is capable of predicting progressive composite damage and failure, a sensitivity analysis is completed to establish which material parameters are truly relevant to a simulation's outcome. Then, a parameter study is completed to determine the effect of the relevant material properties' expected variations on the simulated four-point flexural behavior as well as to determine the value of an unknown material property. This process demonstrates the ability to formulate accurate predictions in the absence of a rigorous material characterization effort. Finally, the presented results indicate that a sensitivity analysis and parameter study can be used to streamline the material definition process as the described flexural characterization was used for model validation.

  14. Composite laminate failure parameter optimization through four-point flexure experimentation and analysis

    DOE PAGES

    Nelson, Stacy; English, Shawn; Briggs, Timothy

    2016-05-06

    Fiber-reinforced composite materials offer light-weight solutions to many structural challenges. In the development of high-performance composite structures, a thorough understanding is required of the composite materials themselves as well as methods for the analysis and failure prediction of the relevant composite structures. However, the mechanical properties required for the complete constitutive definition of a composite material can be difficult to determine through experimentation. Therefore, efficient methods are necessary that can be used to determine which properties are relevant to the analysis of a specific structure and to establish a structure's response to a material parameter that can only be definedmore » through estimation. The objectives of this paper deal with demonstrating the potential value of sensitivity and uncertainty quantification techniques during the failure analysis of loaded composite structures; and the proposed methods are applied to the simulation of the four-point flexural characterization of a carbon fiber composite material. Utilizing a recently implemented, phenomenological orthotropic material model that is capable of predicting progressive composite damage and failure, a sensitivity analysis is completed to establish which material parameters are truly relevant to a simulation's outcome. Then, a parameter study is completed to determine the effect of the relevant material properties' expected variations on the simulated four-point flexural behavior as well as to determine the value of an unknown material property. This process demonstrates the ability to formulate accurate predictions in the absence of a rigorous material characterization effort. Finally, the presented results indicate that a sensitivity analysis and parameter study can be used to streamline the material definition process as the described flexural characterization was used for model validation.« less

  15. Fault-tolerant analysis and control of SSRMS-type manipulators with single-joint failure

    NASA Astrophysics Data System (ADS)

    She, Yu; Xu, Wenfu; Su, Haijun; Liang, Bin; Shi, Hongliang

    2016-03-01

    Several space manipulators, whose configurations are similar to that of the Space Station Remote Manipulator System (SSRMS, also called Canadarm2), are playing important roles in the construction and maintenance of the International Space Station. Working in the harsh orbital environment, they are at high risk of single-joint failure. Fault-tolerant capability is critical for those manipulators to complete their on-orbital tasks. In this paper, we analysed and compared the manipulation capability of SSRMS-type manipulators with joints locked at arbitrary positions, and proposed efficient path planning via a fault-tolerant control method. First, a unified kinematic model of this type of manipulators was established. Second, the manipulation capability of the original 7-DOF (degrees of freedom) redundant manipulator was analysed and compared with its degraded 6-DOF counterparts formed by different joint locking configurations. Then, we identified those joints with large sensitivity to fault tolerance performance. The influences of different positions of all joints were also determined by numerical computation. Based on the analysis, the relatively safe and dangerous regions for each joint failure were identified. Finally, we proposed a path planning strategy and realized by a H∞ controller which enables the failure joint locked in the safe region, and simulations were carried on a degraded 3-DOF planar redundant manipulator to verify the planning strategy and control approach. This paper provided important analysis results and efficient methods to address the possible problems of SSRMS-type manipulators caused by single-joint failure that can be extended to other types of manipulators. Moreover, the proposed method is useful for designing the optimal configuration of a redundant manipulator.

  16. Computer-aided analysis of star shot films for high-accuracy radiation therapy treatment units.

    PubMed

    Depuydt, Tom; Penne, Rudi; Verellen, Dirk; Hrbacek, Jan; Lang, Stephanie; Leysen, Katrien; Vandevondel, Iwein; Poels, Kenneth; Reynders, Truus; Gevaert, Thierry; Duchateau, Michael; Tournel, Koen; Boussaer, Marlies; Cosentino, Dorian; Garibaldi, Cristina; Solberg, Timothy; De Ridder, Mark

    2012-05-21

    As mechanical stability of radiation therapy treatment devices has gone beyond sub-millimeter levels, there is a rising demand for simple yet highly accurate measurement techniques to support the routine quality control of these devices. A combination of using high-resolution radiosensitive film and computer-aided analysis could provide an answer. One generally known technique is the acquisition of star shot films to determine the mechanical stability of rotations of gantries and the therapeutic beam. With computer-aided analysis, mechanical performance can be quantified as a radiation isocenter radius size. In this work, computer-aided analysis of star shot film is further refined by applying an analytical solution for the smallest intersecting circle problem, in contrast to the gradient optimization approaches used until today. An algorithm is presented and subjected to a performance test using two different types of radiosensitive film, the Kodak EDR2 radiographic film and the ISP EBT2 radiochromic film. Artificial star shots with a priori known radiation isocenter size are used to determine the systematic errors introduced by the digitization of the film and the computer analysis. The estimated uncertainty on the isocenter size measurement with the presented technique was 0.04 mm (2σ) and 0.06 mm (2σ) for radiographic and radiochromic films, respectively. As an application of the technique, a study was conducted to compare the mechanical stability of O-ring gantry systems with C-arm-based gantries. In total ten systems of five different institutions were included in this study and star shots were acquired for gantry, collimator, ring, couch rotations and gantry wobble. It was not possible to draw general conclusions about differences in mechanical performance between O-ring and C-arm gantry systems, mainly due to differences in the beam-MLC alignment procedure accuracy. Nevertheless, the best performing O-ring system in this study, a BrainLab/MHI Vero system

  17. Computer-aided analysis of star shot films for high-accuracy radiation therapy treatment units

    NASA Astrophysics Data System (ADS)

    Depuydt, Tom; Penne, Rudi; Verellen, Dirk; Hrbacek, Jan; Lang, Stephanie; Leysen, Katrien; Vandevondel, Iwein; Poels, Kenneth; Reynders, Truus; Gevaert, Thierry; Duchateau, Michael; Tournel, Koen; Boussaer, Marlies; Cosentino, Dorian; Garibaldi, Cristina; Solberg, Timothy; De Ridder, Mark

    2012-05-01

    As mechanical stability of radiation therapy treatment devices has gone beyond sub-millimeter levels, there is a rising demand for simple yet highly accurate measurement techniques to support the routine quality control of these devices. A combination of using high-resolution radiosensitive film and computer-aided analysis could provide an answer. One generally known technique is the acquisition of star shot films to determine the mechanical stability of rotations of gantries and the therapeutic beam. With computer-aided analysis, mechanical performance can be quantified as a radiation isocenter radius size. In this work, computer-aided analysis of star shot film is further refined by applying an analytical solution for the smallest intersecting circle problem, in contrast to the gradient optimization approaches used until today. An algorithm is presented and subjected to a performance test using two different types of radiosensitive film, the Kodak EDR2 radiographic film and the ISP EBT2 radiochromic film. Artificial star shots with a priori known radiation isocenter size are used to determine the systematic errors introduced by the digitization of the film and the computer analysis. The estimated uncertainty on the isocenter size measurement with the presented technique was 0.04 mm (2σ) and 0.06 mm (2σ) for radiographic and radiochromic films, respectively. As an application of the technique, a study was conducted to compare the mechanical stability of O-ring gantry systems with C-arm-based gantries. In total ten systems of five different institutions were included in this study and star shots were acquired for gantry, collimator, ring, couch rotations and gantry wobble. It was not possible to draw general conclusions about differences in mechanical performance between O-ring and C-arm gantry systems, mainly due to differences in the beam-MLC alignment procedure accuracy. Nevertheless, the best performing O-ring system in this study, a BrainLab/MHI Vero system

  18. National Responses to HIV/AIDS and Non-Communicable Diseases in Developing Countries: Analysis of Strategic Parallels and Differences

    PubMed Central

    Haregu, Tilahun Nigatu; Setswe, Geoffrey; Elliott, Julian; Oldenburg, Brian

    2014-01-01

    HIV/AIDS and non-communicable diseases (NCDs) epidemics may have many important similarities in their aetiology, pathogenesis and management. Evidence about the similarities and differences between the national responses HIV/AIDS and NCDs is essential for an integrated response. The objective of this study was to examine the parallels and differences between national responses to HIV/AIDS and NCDs in selected developing countries. This study applied a strategic level comparative case study approach as its study design. The main construct was national response to HIV/AIDS and NCDs. The 4 overarching themes were policy response, institutional mechanism, programmatic response and strategic information. Four countries were purposively selected as cases. Data were collected and triangulated from a multiple sources. The focus of analysis included identifying items for comparison, characteristics to be compared, degrees of similarity, and strategic importance of similarities. Analysis of data was qualitative content analysis with within-case, between-case, and across-case comparisons. While the nature of the disease and the contents of national HIV/AIDS and NCD policies are different, the policy processes involved are largely similar. Functional characteristics of programmatic response to HIV/AIDS and NCDs are similar. But the internal constituents are different. Though both HIV and NCDs require both a multi-sectorial response and a national coordination mechanism, the model and the complexity of the coordination are different. Strategic information frameworks for HIV/AIDS and NCDs use similar models. However, the indicators, targets and priorities are different. In conclusion, the national responses between HIV/AIDS and NCDs are largely similar in approaches and functions but different in content. Significance for public health This study explores the parallels and differences between national responses to HIV/AIDS and non-communicable diseases (NCDs). The identified

  19. An Analysis of Teacher Aide Administrative Practices in Kansas Public Schools, 1978-79.

    ERIC Educational Resources Information Center

    Creamer, Robert C.

    Responses to a questionnaire sent to all Kansas public school districts with enrollments of 500 and over revealed several characteristics of teacher aide utilization in the state. Such utilization is increasing, especially among larger districts where paid aides predominated over volunteers. In most districts all aides were paid, usually by the…

  20. Checkerboard II: An Analysis of Tax Effort, Equalization and Extraordinary Needs Aids

    ERIC Educational Resources Information Center

    Widerquist, Karl

    2001-01-01

    A proposal in the New York State Assembly in 2000 considered eliminating Tax Equalization Aid to school districts in order to fund the elimination of aid caps, called Transition Adjustment. In response to that proposal, this report examines the equalizing or disequalizing effects of three types of New York state aid to school…

  1. Computer-aided analysis and design of the shape rolling process for producing turbine engine airfoils

    NASA Technical Reports Server (NTRS)

    Lahoti, G. D.; Akgerman, N.; Altan, T.

    1978-01-01

    Mild steel (AISI 1018) was selected as model cold-rolling material and Ti-6Al-4V and INCONEL 718 were selected as typical hot-rolling and cold-rolling alloys, respectively. The flow stress and workability of these alloys were characterized and friction factor at the roll/workpiece interface was determined at their respective working conditions by conducting ring tests. Computer-aided mathematical models for predicting metal flow and stresses, and for simulating the shape-rolling process were developed. These models utilize the upper-bound and the slab methods of analysis, and are capable of predicting the lateral spread, roll-separating force, roll torque and local stresses, strains and strain rates. This computer-aided design (CAD) system is also capable of simulating the actual rolling process and thereby designing roll-pass schedule in rolling of an airfoil or similar shape. The predictions from the CAD system were verified with respect to cold rolling of mild steel plates. The system is being applied to cold and hot isothermal rolling of an airfoil shape, and will be verified with respect to laboratory experiments under controlled conditions.

  2. Deadly AIDS policy failure by the highest levels of the US government: a personal look back 30 years later for lessons to respond better to future epidemics.

    PubMed

    Francis, Donald P

    2012-08-01

    Successful control of any dangerous epidemic requires: (i) early understanding of the epidemiology of the disease and (ii) rapid applications of preventive interventions. Through the lack of both policy and financial support, the United States Centers for Disease Control (CDC) was severely handicapped during the early years of the AIDS epidemic. Senior staff of the Reagan Administration did not understand the essential role of Government in disease prevention. Although CDC clearly documented the dangers of HIV and AIDS early in the epidemic, refusal by the White House to deliver prevention programs then certainly allowed HIV to become more widely seeded. As much of the international health community relies on CDC for up-to-date prevention advice, these actions by the White House surely increased the spread of HIV around the world. To respond better to future epidemics, we need to understand the deadly forces that inhibited CDC at that time.

  3. 76 FR 70768 - Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-15

    ... From the Federal Register Online via the Government Publishing Office NUCLEAR REGULATORY COMMISSION Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft Report for Comment; Correction AGENCY: Nuclear Regulatory Commission. ACTION: Draft NUREG; request...

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

    SciTech Connect

    Ronald Laurids Boring, PhD

    2014-09-01

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

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

    NASA Technical Reports Server (NTRS)

    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.

  6. Analysis of a Turbine Blade Failure in a Military Turbojet Engine

    NASA Astrophysics Data System (ADS)

    Sahoo, Benudhar; Satpathy, R. K.; Panigrahi, S. K.

    2016-06-01

    This paper deals with failure analysis of a low-pressure turbine blade of a straight flow turbojet engine. The blade is made of a wrought precipitation hardened Nickel base superalloy with oxidation-resistant diffusion aluminizing coating. The failure mode is found to be fatigue with multiple cracks inside the blade having crack origin at metal carbides. In addition to the damage in the coating, carbide banding has been observed in few blades. Carbide banding may be defined as inclusions in the form of highly elongated along deformation direction. The size, shape and banding of carbides and their location critically affect the failure of blades. Carbon content needs to be optimized to reduce interdendritic segregation and thereby provide improved fatigue and stress rupture life. Hence, optimization of size, shape and distribution of carbides in the billet and forging parameters during manufacturing of blade play a vital role to eliminate/reduce extent of banding. Reference micrographs as acceptance criteria are essential for evaluation of raw material and blade. There is a need to define the acceptance criteria for carbide bandings and introduce more sensitive ultrasonic check during billet and on finished blade inspection.

  7. Failure Analysis Results and Corrective Actions Implemented for the EMU 3011 Water in the Helmet Mishap

    NASA Technical Reports Server (NTRS)

    Steele, John; Metselaar, Carol; Peyton, Barbara; Rector, Tony; Rossato, Robert; Macias, Brian; Weigel, Dana; Holder, Don

    2015-01-01

    During EVA (Extravehicular Activity) No. 23 aboard the ISS (International Space Station) on 07/16/2013 water entered the EMU (Extravehicular Mobility Unit) helmet resulting in the termination of the EVA (Extravehicular Activity) approximately 1-hour after it began. It was estimated that 1.5-L of water had migrated up the ventilation loop into the helmet, adversely impacting the astronauts hearing, vision and verbal communication. Subsequent on-board testing and ground-based TT and E (Test, Tear-down and Evaluation) of the affected EMU hardware components led to the determination that the proximate cause of the mishap was blockage of all water separator drum holes with a mixture of silica and silicates. The blockages caused a failure of the water separator function which resulted in EMU cooling water spilling into the ventilation loop, around the circulating fan, and ultimately pushing into the helmet. The root cause of the failure was determined to be ground-processing short-comings of the ALCLR (Airlock Cooling Loop Recovery) Ion Filter Beds which led to various levels of contaminants being introduced into the Filters before they left the ground. Those contaminants were thereafter introduced into the EMU hardware on-orbit during ALCLR scrubbing operations. This paper summarizes the failure analysis results along with identified process, hardware and operational corrective actions that were implemented as a result of findings from this investigation.

  8. [Failure Prediction of Power-Shift Steering Transmission Based on Oil Spectral Analysis with Wiener Process].

    PubMed

    Liu, Yong; Ma, Biao; Zheng, Chang-song; Xie, Shang-yu

    2015-09-01

    The most common methodology used in element concentration measurement and analyzing of wear particles is Atomic emission (AE) spectroscopy. As an indirect measuring method, the oil spectral data is introduced to indicate the performance degradation and the residual life prediction in the reliability evaluation of Power shift steering transmission (PSST). Stochastic methods especially the Wiener process is convenient in solving and analyzing the unitary degradation failure indicated by the oil spectral data. The oil data have been sampled in the real operating condition, and the data set has more than 50 samples taken from PSST. The mean values and time-dependent characteristics of three indicating elements are statistically obtained by the linear regression analysis. The model of the degradation and failure prediction has been proposed based on the Wiener process with the positive drift. For modeling and simulation the software R was used. Therefore, the trend curves of diffusion process with their First Hitting Time have been predicted. Through comparison, the time intervals of condition-based maintenance have been extended as 27 Mh (15.9%). This will save the cost of maintenances by eliminate the preventive maintained cycles. The advantage and novelty of the outcomes presented in the article are that the stochastic process might be applied for predicting the degradation failure occurrence and also for optimizing the maintenance intervals and the cost-benefit. As might be expected, the method can be extended to other cases of wear prediction and evaluation in complex mechanical system.

  9. Difficult Decisions: AIDS.

    ERIC Educational Resources Information Center

    Slesnick, Irwin L.

    1988-01-01

    Focuses on public education about the acquired immune deficiency syndrome (AIDS) epidemic. Discusses the problems of a second epidemic of fear and anxiety. Presents several questions for classroom discussion and analysis of the public fear of AIDS. Gives some statistics highlighting misinformation about AIDS. (CW)

  10. Case history: Failure analysis of a 16K ROM with a polysilicon gate defect

    SciTech Connect

    Mikawa, R.E.; Campbell, A.N.

    1993-08-01

    This case history presents the analysis of a very unusual CMOS 2K {times} 8 read only memory (ROM) failure. The IC failure was discovered after a 1,000 hour, 150{degree}C static life test. Elevated quiescent power supply current was present that caused the IC to fail parametric testing, but the IC was fully functional at the specified operating power supply voltage of 10 V. Functional failures were ``forced`` by operating the IC at below nominal voltage. Electron beam probing and dynamic voltage contrast imaging performed while the IC was in the functional failing mode indicated the presence of an electrical open circuit in the polysilicon gate interconnect of a p-channel transistor. The IC was deprocessed down to the polysilicon and the defective gate was examined with a scanning electron microscope. An abrupt change in microstructure was observed at the location corresponding to the site of electrical discontinuity. Circuit simulations, performed using a series gate resistance to model the defective gate, showed that the gate signal to the p-channel transistor changed phase and high current was present if the gate resistance exceeded 1 {times} 10{sup 9} ohms. The change in microstructure and increased gate resistance are consistent with a localized reduction of dopant (phosphorus) concentration. During the life test, it is speculated that phosphorus segregated to the grain boundaries resulting in a net reduction of dopant atoms and a corresponding decrease in the conductivity of the polysilicon gate. This IC failure is apparently due to dopant segregation and carrier trapping at the grain boundaries in the polysilicon during the high temperature life test.

  11. Garrett County Aids AID

    ERIC Educational Resources Information Center

    Appalachia, 1975

    1975-01-01

    Garrett County, Maryland volunteered to act as a pre-overseas learning laboratory for AID (Agency for International Development) interns who practiced data collection and planning techniques with the help of local citizenry. (JC)

  12. APols-aided protein precipitation: a rapid method for concentrating proteins for proteomic analysis.

    PubMed

    Ning, Zhibin; Hawley, Brett; Seebun, Deeptee; Figeys, Daniel

    2014-10-01

    Amphipols (APols) are a newly designed and milder class of detergent. They have been used primarily in protein structure analysis for membrane protein trapping and stabilization. We have recently demonstrated that APols can be used as an alternative detergent for proteome extraction and digestion, to achieve a "One-stop" single-tube workflow for proteomics. In this workflow, APols are removed by precipitation after protein digestion without depleting the digested peptides. Here, we took further advantage of this precipitation characteristic of APols to concentrate proteins from diluted samples. In contrast with tryptic peptides, a decrease in pH leads to the unbiased co-precipitation of APols with proteins, including globular hydrophilic proteins. We demonstrated that this precipitation is a combined effect of acid precipitation and the APols' protein interactions. Also, we have been able to demonstrate that APols-aided protein precipitation works well on diluted samples, such as secretome sample, and provides a rapid method for protein concentration.

  13. Analysis of performance losses of direct ethanol fuel cells with the aid of a reference electrode

    NASA Astrophysics Data System (ADS)

    Li, Guangchun; Pickup, Peter G.

    The performances of direct ethanol fuel cells with different anode catalysts, different ethanol concentrations, and at different operating temperatures have been studied. The performance losses of the cell have been separated into individual electrode performance losses with the aid of a reference electrode, ethanol crossover has been quantified, and CO 2 and acetic acid production have been measured by titration. It has been shown that the cell performance strongly depends on the anode catalyst, ethanol concentration, and operating temperature. It was found that the cathode and anode exhibit different dependences on ethanol concentration and operating temperature. The performance of the cathode is very sensitive to the rate of ethanol crossover. Product analysis provides insights into the mechanisms of electro-oxidation of ethanol.

  14. Computer-aided diagnosis of knee-joint disorders via vibroarthrographic signal analysis: a review.

    PubMed

    Wu, Yunfeng; Krishnan, Sridhar; Rangayyan, Rangaraj M

    2010-01-01

    The knee is the lower-extremity joint that supports nearly the entire weight of the human body. It is susceptible to osteoarthritis and other knee-joint disorders caused by degeneration or loss of articular cartilage. The detection of a knee-joint abnormality at an early stage is important, because it helps increase therapeutic options that may slow down the degenerative process. Imaging-based arthrographic modalities can provide anatomical images of the joint cartilage surfaces, but fail to demonstrate the functional integrity of the cartilage. Knee-joint auscultation, by means of recording the vibroarthrographic (VAG) signal during bending motion of a knee, could be used to develop a noninvasive diagnostic tool. Computer-aided analysis of VAG signals could provide quantitative indices for screening of degenerative conditions of the cartilage surface and staging of osteoarthritis. In addition, the diagnosis of knee-joint pathology by means of VAG signal analysis may reduce the number of semi-invasive diagnostic arthroscopic examinations. This article reviews studies related to VAG signal analysis, first summarizing the pilot studies that demonstrated the diagnostic potential of knee-joint auscultation for the detection of degenerative diseases, and then describing the details of recent progress in analysis of VAG signals using temporal analysis, frequency-domain analysis, time-frequency analysis, and statistical modeling. The decision-making methods used in the related studies are summarized, followed by a comparison of the diagnostic performance achieved by different pattern classifiers. The final section is a perspective on the future and further development of VAG signal analysis.

  15. Interference fits and stress-corrosion failure. [aircraft parts fatigue life analysis

    NASA Technical Reports Server (NTRS)

    Hanagud, S.; Carter, A. E.

    1976-01-01

    It is pointed out that any proper design of interference fit fastener, interference fit bushings, or stress coining processes should consider both the stress-corrosion susceptibility and fatigue-life improvement together. Investigations leading to such a methodology are discussed. A service failure analysis of actual aircraft parts is considered along with the stress-corrosion susceptibility of cold-working interference fit bushings. The optimum design of the amount of interference is considered, giving attention to stress formulas and aspects of design methodology.

  16. Computer aided boar semen motility analysis for cereulide detection in different food matrices.

    PubMed

    Rajkovic, Andreja; Uyttendaele, Mieke; Debevere, Johan

    2007-02-28

    Computer Aided Semen Analysis (CASA) study of the boar semen motility has been demonstrated to be an appropriate assay for detection of cereulide (Bacillus cereus emetic toxin). Application of the boar semen bio-assay to detect cereulide directly in foods requires investigation of potential interference of food components, preservatives and other microbial and chemical food contaminants with the bio-assay. Current study provides evidence that none of included Staphylococcus aureus enterotoxins A, B, C and D nor B. cereus Hemolysin BL (HBL) and non-hemolytic enterotoxin (NHE) and three mycotoxins (Sterigmatocystin, Fumonisin B1 and Patulin) exhibited a toxic impact on semen progressive motility. Aflatoxin M1, M3 and zearalenone impaired semen motility only at concentrations (0.004 mg ml(-1), 0.1 mg ml(-1) and 10 mg ml(-1), respectively) much higher than those found in foods and those permitted by legislation, in comparison to cereulide which induces motility cease at concentrations lower than 20 ng ml(-1). Ten commonly used preservatives, namely potassium sorbate, sodium benzoate, (DL) malic acid, citric acid, (L+) tartaric acid, acetic acid, (DL) lactic acid, (L+) ascorbic acid, sodium chloride and sucrose induced no cease in spermatozoa motility even at preservative concentrations higher than permitted by legislation. Dioxins, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), and acrylamide had no acute effect on spermatozoa motility at concentrations of 500 and 10,000 mg ml(-1), respectively. Robustness of computer aided boar semen motility analysis, tested with 14 different foods inoculated with cereulide producing B. cereus, showed distinct cereulide production in seven samples (although B. cereus growth to counts higher than 8 log CFU g(-1) was noted in 11 samples), in amounts close to those reported in foodborne outbreaks. Test evaluation in 33 samples suspected to hold cereulide showed actual cereulide presence in ten samples and no interference of food matrix

  17. Diagnosis of repeated failures in discrete event systems.

    SciTech Connect

    Garcia, H. E.; Jiang, S.; Kumar, R.; Univ. of Kentucky; Iowa State Univ.

    2002-01-01

    We introduce the notion of repeated failure diagnosability for diagnosing the occurrence of a repeated number of failures in discrete event systems. This generalizes the earlier notion of diagnosability that was used to diagnose the occurrence of a failure, but from which the information regarding the multiplicity of the occurrence of the failure could not be obtained. It is possible that in some systems the same type of failure repeats a multiple number of times. It is desirable to have a diagnoser which not only diagnoses that such a failure has occurred but also determines the number of times the failure has occurred. To aide such analysis we introduce the notions of K-diagnosability (K failures diagnosability), [1, K]-diagnosability (1 through K failures diagnosability), and [1, /spl infin/]-diagnosability (1 through /spl infin/ failures diagnosability). Here the first notion is the weakest of all three, and the earlier notion of diagnosability is the same as that of K-diagnosability or that of [1, K]-diagnosability with K=1. We give polynomial algorithms for checking these various notions of repeated failure diagnosability, and also present a procedure of polynomial complexity for the online diagnosis of repeated failures.

  18. Diagnosis of repeated/intermittent failures in discrete event systems.

    SciTech Connect

    Garcia, H. E.; Jiang, S.; Kumar, R.

    2003-04-01

    We introduce the notion of repeated failure diagnosability for diagnosing the occurrence of a repeated number of failures in discrete event systems. This generalizes the earlier notion of diagnosability that was used to diagnose the occurrence of a failure, but from which the information regarding the multiplicity of the occurrence of the failure could not be obtained. It is possible that in some systems the same type of failure repeats a multiple number of times. It is desirable to have a diagnoser which not only diagnoses that such a failure has occurred but also determines the number of times the failure has occurred. To aide such analysis we introduce the notions of K-diagnosability (K failures diagnosability), [1,K]-diagnosability (1 through K failures diagnosability), and [1,1]-diagnosability (1 through 1 failures diagnosability). Here the rst (resp., last) notion is the weakest (resp., strongest) of all three, and the earlier notion of diagnosability is the same as that of K-diagnosability or that of [1,K]- diagnosability with K = 1. We give polynomial algorithms for checking these various notions of repeated failure diagnosability, and also present a procedure of polynomial complexity for the on-line diagnosis of repeated failures.

  19. Geometrical characteristics of left ventricular dyssynchrony in advanced heart failure. Myocardial strain analysis by tagged MRI.

    PubMed

    Nagao, Michinobu; Yamasaki, Yuzo; Yonezawa, Masato; Kamitani, Takeshi; Kawanami, Satoshi; Mukai, Yasushi; Higo, Taiki; Yabuuchi, Hidetake; Sunagawa, Kenji; Honda, Hiroshi

    2014-01-01

    The aims of this study were to quantify the geometrical differences in left ventricular (LV) dyssynchrony in patients with heart failure (HF) using cine-tagged MRI, and to investigate the relationship between dyssynchrony and major adverse cardiac events (MACE) in HF.In 67 patients with HF [mean LV ejection fraction (LVEF), 34%], cardiac MRI using a 3-Tesla scanner was performed. The dyssynchrony time between septal and lateral segments (SL-DT) and between basal and apical segments (BA-DT) was computed by cross-correlation analysis of the strain time-curves from the cine-tagged MRI. After receiving optimal medical treatment, all patients were followed-up for a mean period of 27 months. The primary endpoint was MACE that consisted of cardiac death or HF hospitalization or a left ventricular assist device due to refractory pump failure. Multivariate logistic regression analysis was performed to determine the ability of SL-DT, BA-DT, and HF biomarkers to predict MACE.Multivariate logistic regression analysis showed that the odds ratio to predict MACE was 0.935 for LVEF (P = 0.021), 1.016 for BA-DT (P = 0.026), and 0.971 for systolic blood pressure (P = 0.126).The results show that basal-apical dyssynchrony is an independent predictor of MACE in HF patients.

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

    PubMed Central

    Bittencourt, Hugo Souza; dos Reis, Helena França Correia; Lima, Melissa Santos; Gomes Neto, Mansueto

    2017-01-01

    Non-invasive ventilation (NIV) may perfect respiratory and cardiac performance in patients with heart failure (HF). The objective of the study to establish, through systematic review and meta-analysis, NIV influence on functional capacity of HF patients. A systematic review with meta-analysis of randomized studies was carried out through research of databases of Cochrane Library, SciELO, Pubmed and PEDro, using the key-words: heart failure, non-invasive ventilation, exercise tolerance; and the free terms: bi-level positive airway pressure (BIPAP), continuous positive airway pressure (CPAP), and functional capacity (terms were searched for in English and Portuguese) using the Boolean operators AND and OR. Methodological quality was ensured through PEDro scale. Weighted averages and a 95% confidence interval (CI) were calculated. The meta-analysis was done thorugh the software Review Manager, version 5.3 (Cochrane Collaboration). Four randomized clinical trials were included. Individual studies suggest NIV improved functional capacity. NIV resulted in improvement in the distance of the six-minute walk test (6MWT) (68.7m 95%CI: 52.6 to 84.9) in comparison to the control group. We conclude that the NIV is an intervention that promotes important effects in the improvement of functional capacity of HF patients. However, there is a gap in literature on which are the most adequate parameters for the application of this technique. PMID:28099587

  1. Enhanced characterization of solid solitary pulmonary nodules with Bayesian analysis-based computer-aided diagnosis

    PubMed Central

    Perandini, Simone; Soardi, Gian Alberto; Motton, Massimiliano; Augelli, Raffaele; Dallaserra, Chiara; Puntel, Gino; Rossi, Arianna; Sala, Giuseppe; Signorini, Manuel; Spezia, Laura; Zamboni, Federico; Montemezzi, Stefania

    2016-01-01

    The aim of this study was to prospectively assess the accuracy gain of Bayesian analysis-based computer-aided diagnosis (CAD) vs human judgment alone in characterizing solitary pulmonary nodules (SPNs) at computed tomography (CT). The study included 100 randomly selected SPNs with a definitive diagnosis. Nodule features at first and follow-up CT scans as well as clinical data were evaluated individually on a 1 to 5 points risk chart by 7 radiologists, firstly blinded then aware of Bayesian Inference Malignancy Calculator (BIMC) model predictions. Raters’ predictions were evaluated by means of receiver operating characteristic (ROC) curve analysis and decision analysis. Overall ROC area under the curve was 0.758 before and 0.803 after the disclosure of CAD predictions (P = 0.003). A net gain in diagnostic accuracy was found in 6 out of 7 readers. Mean risk class of benign nodules dropped from 2.48 to 2.29, while mean risk class of malignancies rose from 3.66 to 3.92. Awareness of CAD predictions also determined a significant drop on mean indeterminate SPNs (15 vs 23.86 SPNs) and raised the mean number of correct and confident diagnoses (mean 39.57 vs 25.71 SPNs). This study provides evidence supporting the integration of the Bayesian analysis-based BIMC model in SPN characterization. PMID:27648166

  2. Fault tree analysis of failure cause of crushing plant and mixing bed hall at Khoy cement factory in Iran☆

    PubMed Central

    Nouri.Gharahasanlou, Ali; Mokhtarei, Ashkan; Khodayarei, Aliasqar; Ataei, Mohammad

    2014-01-01

    Evaluating and analyzing the risk in the mining industry is a new approach for improving the machinery performance. Reliability, safety, and maintenance management based on the risk analysis can enhance the overall availability and utilization of the mining technological systems. This study investigates the failure occurrence probability of the crushing and mixing bed hall department at Azarabadegan Khoy cement plant by using fault tree analysis (FTA) method. The results of the analysis in 200 h operating interval show that the probability of failure occurrence for crushing, conveyor systems, crushing and mixing bed hall department is 73, 64, and 95 percent respectively and the conveyor belt subsystem found as the most probable system for failure. Finally, maintenance as a method of control and prevent the occurrence of failure is proposed. PMID:26779433

  3. Stress Analysis of B-52B and B-52H Air-Launching Systems Failure-Critical Structural Components

    NASA Technical Reports Server (NTRS)

    Ko, William L.

    2005-01-01

    The operational life analysis of any airborne failure-critical structural component requires the stress-load equation, which relates the applied load to the maximum tangential tensile stress at the critical stress point. The failure-critical structural components identified are the B-52B Pegasus pylon adapter shackles, B-52B Pegasus pylon hooks, B-52H airplane pylon hooks, B-52H airplane front fittings, B-52H airplane rear pylon fitting, and the B-52H airplane pylon lower sway brace. Finite-element stress analysis was performed on the said structural components, and the critical stress point was located and the stress-load equation was established for each failure-critical structural component. The ultimate load, yield load, and proof load needed for operational life analysis were established for each failure-critical structural component.

  4. Teaching AIDS.

    PubMed

    Short, R V

    1989-06-01

    This article reviews a peer group Acquired Immunodeficiency Syndrome (AIDS) educational program at a university in Australia. Studies in the US have shown that most adolescents, although sexually active, do not believe they are likely to become infected with the Human Immunodeficiency Virus, and therefore do not attempt to modify their sexual behavior. A 1st step in educating students is to introduce them to condoms and impress upon them the fact that condoms should be used at the beginning of all sexual relationships, whether homosexual or heterosexual. In this program 3rd year medical students were targeted, as they are effective communicators and disseminators of information to the rest of the student body. After class members blow up condoms, giving them a chance to handle various brands and observe the varying degrees of strength, statistical evidence about the contraceptive failure rate of condoms (0.6-14.7 per 100 women-years) is discussed. Spermicides, such as nonoxynol-9 used in conjunction with condoms, are also discussed, as are condoms for women, packaging and marketing of condoms, including those made from latex and from the caecum of sheep, the latter condoms being of questionable effectiveness in preventing transmission of the virus. The care of terminal AIDS cases and current global and national statistics on AIDS are presented. The program also includes cash prizes for the best student essays on condom use, the distribution of condoms, condom key rings and T-shirts, and a student-run safe sex stand during orientation week. All of these activities are intended to involve students and attract the interest of the undergraduate community. Questionnaires administered to students at the end of the course revealed that the lectures were received favorably. Questionnaires administered to new medical and English students attending orientation week revealed that 72% of students thought the stand was a good idea and 81% and 83%, respectively found it

  5. The Development of Technological Support for RAF Early Failure Detection Centers.

    DTIC Science & Technology

    2007-11-02

    Key Words: Computer aided ; CASPA ; CAVE; debris analysis; Early Failure Detection Centres; equipment health monitoring; Royal Air Force; Wear Particle...of neural networks and image analysis techniques. CASPA : The Computer Aided Systematic Particle Analysis ( CASPA ) system has been developed as a...advantages of CASPA is that, as an expert system it may be 2 used by inexperienced personnel, while repeated use will train the operator in the

  6. SU-E-T-495: Neutron Induced Electronics Failure Rate Analysis for a Single Room Proton Accelerator

    SciTech Connect

    Knutson, N; DeWees, T; Klein, E

    2014-06-01

    Purpose: To determine the failure rate as a function of neutron dose of the range modulator's servo motor controller system (SMCS) while shielded with Borated Polyethylene (BPE) and unshielded in a single room proton accelerator. Methods: Two experimental setups were constructed using two servo motor controllers and two motors. Each SMCS was then placed 30 cm from the end of the plugged proton accelerator applicator. The motor was then turned on and observed from outside of the vault while being irradiated to known neutron doses determined from bubble detector measurements. Anytime the motor deviated from the programmed motion a failure was recorded along with the delivered dose. The experiment was repeated using 9 cm of BPE shielding surrounding the SMCS. Results: Ten SMCS failures were recorded in each experiment. The dose per monitor unit for the unshielded SMCS was 0.0211 mSv/MU and 0.0144 mSv/MU for the shielded SMCS. The mean dose to produce a failure for the unshielded SMCS was 63.5 ± 58.3 mSv versus 17.0 ±12.2 mSv for the shielded. The mean number of MUs between failures were 2297 ± 1891 MU for the unshielded SMCS and 2122 ± 1523 MU for the shielded. A Wilcoxon Signed Ranked test showed the dose between failures were significantly different (P value = 0.044) while the number of MUs between failures were not (P value = 1.000). Statistical analysis determined a SMCS neutron dose of 5.3 mSv produces a 5% chance of failure. Depending on the workload and location of the SMCS, this failure rate could impede clinical workflow. Conclusion: BPE shielding was shown to not reduce the average failure of the SMCS and relocation of the system outside of the accelerator vault was required to lower the failure rate enough to avoid impeding clinical work flow.

  7. Comparison Study of Electromagnet and Permanent Magnet Systems for an Accelerator Using Cost-Based Failure Modes and Effects Analysis.

    SciTech Connect

    Spencer, C

    2004-02-19

    The next generation of particle accelerators will be one-of-a-kind facilities, and to meet their luminosity goals they must have guaranteed availability over their several decade lifetimes. The Next Linear Collider (NLC) is one viable option for a 1 TeV electron-positron linear collider, it has an 85% overall availability goal. We previously showed how a traditional Failure Modes and Effects Analysis (FMEA) of a SLAC electromagnet leads to reliability-enhancing design changes. Traditional FMEA identifies failure modes with high risk but does not consider the consequences in terms of cost, which could lead to unnecessarily expensive components. We have used a new methodology, ''Life Cost-Based FMEA'', which measures risk of failure in terms of cost, in order to evaluate and compare two different technologies that might be used for the 8653 NLC magnets: electromagnets or permanent magnets. The availabilities for the two different types of magnet systems have been estimated using empirical data from SLAC's accelerator failure database plus expert opinion on permanent magnet failure modes and industry standard failure data. Labor and material costs to repair magnet failures are predicted using a Monte Carlo simulation of all possible magnet failures over a 30-year lifetime. Our goal is to maximize up-time of the NLC through magnet design improvements and the optimal combination of electromagnets and permanent magnets, while reducing magnet system lifecycle costs.

  8. Failure mode and effects analysis of skin electronic brachytherapy using Esteya® unit

    PubMed Central

    Bautista-Ballesteros, Juan Antonio; Bonaque, Jorge; Celada, Francisco; Lliso, Françoise; Carmona, Vicente; Gimeno-Olmos, Jose; Ouhib, Zoubir; Rosello, Joan; Perez-Calatayud, Jose

    2016-01-01

    Purpose Esteya® (Nucletron, an Elekta company, Elekta AB, Stockholm, Sweden) is an electronic brachytherapy device used for skin cancer lesion treatment. In order to establish an adequate level of quality of treatment, a risk analysis of the Esteya treatment process has been done, following the methodology proposed by the TG-100 guidelines of the American Association of Physicists in Medicine (AAPM). Material and methods A multidisciplinary team familiar with the treatment process was formed. This team developed a process map (PM) outlining the stages, through which a patient passed when subjected to the Esteya treatment. They identified potential failure modes (FM) and each individual FM was assessed for the severity (S), frequency of occurrence (O), and lack of detection (D). A list of existing quality management tools was developed and the FMs were consensually reevaluated. Finally, the FMs were ranked according to their risk priority number (RPN) and their S. Results 146 FMs were identified, 106 of which had RPN ≥ 50 and 30 had S ≥ 7. After introducing the quality management tools, only 21 FMs had RPN ≥ 50. The importance of ensuring contact between the applicator and the surface of the patient’s skin was emphasized, so the setup was reviewed by a second individual before each treatment session with periodic quality control to ensure stability of the applicator pressure. Some of the essential quality management tools are already being implemented in the installation are the simple templates for reproducible positioning of skin applicators, that help marking the treatment area and positioning of X-ray tube. Conclusions New quality management tools have been established as a result of the application of the failure modes and effects analysis (FMEA) treatment. However, periodic update of the FMEA process is necessary, since clinical experience has suggested occurring of further new possible potential failure modes. PMID:28115958

  9. Use of failure mode effect analysis (FMEA) to improve medication management process.

    PubMed

    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

  10. Iridium: failures & successes

    NASA Astrophysics Data System (ADS)

    Christensen, CarissaBryce; Beard, Suzette

    2001-03-01

    This paper will provide an overview of the Iridium business venture in terms of the challenges faced, the successes achieved, and the causes of the ultimate failure of the venture — bankruptcy and system de-orbit. The paper will address technical, business, and policy issues. The intent of the paper is to provide a balanced and accurate overview of the Iridium experience, to aid future decision-making by policy makers, the business community, and technical experts. Key topics will include the history of the program, the objectives and decision-making of Motorola, the market research and analysis conducted, partnering strategies and their impact, consumer equipment availability, and technical issues — target performance, performance achieved, technical accomplishments, and expected and unexpected technical challenges. The paper will use as sources trade media and business articles on the Iridium program, technical papers and conference presentations, Wall Street analyst's reports, and, where possible, interviews with participants and close observers.

  11. ISTFA 1987 - International Symposium for Testing and Failure Analysis: Advanced materials; Proceedings of the Symposium, Los Angeles, CA, Nov. 9-13, 1987

    SciTech Connect

    Not Available

    1987-01-01

    The present conference discusses topics in the failure analysis of metallic materials, metal-matrix composites (MMCs), environmental effects on metallics materials, the failure analysis of polymers and ceramics and of resin-based composites, case histories in metal-failure analysis, failure-mechanisms in resin-based composites, innovations in test methodologies, and failures in weldments. Attention is given to fatigue cracking in Al-Li alloys, flow and fracture in discontinuous MMCs with high ductility, the service failure of a 7049 T73 Al alloy aircraft forging, the fracture behavior of electronic ceramics, microscopy of composite delamination, a helicopter crew-seat failure analysis, cracking in marine composites, quantitative fractography, and the significance of repair welds in service failures.

  12. Three-dimensional computer-aided human factors engineering analysis of a grafting robot.

    PubMed

    Chiu, Y C; Chen, S; Wu, G J; Lin, Y H

    2012-07-01

    The objective of this research was to conduct a human factors engineering analysis of a grafting robot design using computer-aided 3D simulation technology. A prototype tubing-type grafting robot for fruits and vegetables was the subject of a series of case studies. To facilitate the incorporation of human models into the operating environment of the grafting robot, I-DEAS graphic software was applied to establish individual models of the grafting robot in line with Jack ergonomic analysis. Six human models (95th percentile, 50th percentile, and 5th percentile by height for both males and females) were employed to simulate the operating conditions and working postures in a real operating environment. The lower back and upper limb stresses of the operators were analyzed using the lower back analysis (LBA) and rapid upper limb assessment (RULA) functions in Jack. The experimental results showed that if a leg space is introduced under the robot, the operator can sit closer to the robot, which reduces the operator's level of lower back and upper limbs stress. The proper environmental layout for Taiwanese operators for minimum levels of lower back and upper limb stress are to set the grafting operation at 23.2 cm away from the operator at a height of 85 cm and with 45 cm between the rootstock and scion units.

  13. Time-to-event analysis of individual variables associated with nursing students' academic failure: a longitudinal study.

    PubMed

    Dante, Angelo; Fabris, Stefano; Palese, Alvisa

    2013-12-01

    Empirical studies and conceptual frameworks presented in the extant literature offer a static imagining of academic failure. Time-to-event analysis, which captures the dynamism of individual factors, as when they determine the failure to properly tailor timely strategies, impose longitudinal studies which are still lacking within the field. The aims of this longitudinal study were to investigate the time which elapses from a nursing student's admission to a Bachelor of Nursing program to their academic failure and to estimate the predictive power of individual variables on academic failure. Enrolled students (n = 170) in two Italian nursing degree programs during academic year 2008-2009, received at the beginning of each years a questionnaire which evaluated individual variables. Academic failure rate was 37.2 %. Time-to-event analysis has shown that academic failure occurred after an average of 664.52 days of course attendance ((95 %)CI = 623.2-705.8). Kaplan-Meier analyses demonstrated a high likelihood of failure among males (χ(2) 7.790, p 0.005) and among those who had obtained a final average grade in their secondary education ≤73/100 (χ(2)11.676, p 0.001). Cox regression analysis confirmed an increased likelihood of failure over time among males as compared to females (HR 1.931, (95 %)CI = 1.017-3.670), and among students living more than a 30 min commute from their place of study (HR 1.898, (95 %)CI = 1.015-3.547). The effect of these two factors on academic failure has been seen to manifest primarily toward the end of students' second academic year; students at risk might be supported by the appropriate university staff prior to this period.

  14. Innocent Victims, Fighter Cells, and White Uncles: A Discourse Analysis of Children's Books about AIDS

    ERIC Educational Resources Information Center

    Blumenreich, Megan; Siegel, Marjorie

    2006-01-01

    In this article, we examine a set of 26 children's books on HIV/AIDS published between 1989-1999 to identify the ways in which these texts construct HIV/AIDS and people living with HIV/AIDS. We explore how this marginalized group is depicted in these books, and how well-meaning teachers may in fact be reproducing dominant discourses about HIV/AIDS…

  15. Intelligent Data Analysis: the Best Approach for Chronic Heart Failure (CHF) Follow Up Management

    PubMed Central

    Mohammadzadeh, Niloofar; Safdari, Reza; Baraani, Alireza; Mohammadzadeh, Farshid

    2014-01-01

    Objective: Intelligent data analysis has ability to prepare and present complex relations between symptoms and diseases, medical and treatment consequences and definitely has significant role in improving follow-up management of chronic heart failure (CHF) patients, increasing speed ​​and accuracy in diagnosis and treatments; reducing costs, designing and implementation of clinical guidelines. The aim: The aim of this article is to describe intelligent data analysis methods in order to improve patient monitoring in follow and treatment of chronic heart failure patients as the best approach for CHF follow up management. Methods: Minimum data set (MDS) requirements for monitoring and follow up of CHF patient designed in checklist with six main parts. All CHF patients that discharged in 2013 from Tehran heart center have been selected. The MDS for monitoring CHF patient status were collected during 5 months in three different times of follow up. Gathered data was imported in RAPIDMINER 5 software. Results: Modeling was based on decision trees methods such as C4.5, CHAID, ID3 and k-Nearest Neighbors algorithm (K-NN) with k=1. Final analysis was based on voting method. Decision trees and K-NN evaluate according to Cross-Validation. Conclusion: Creating and using standard terminologies and databases consistent with these terminologies help to meet the challenges related to data collection from various places and data application in intelligent data analysis. It should be noted that intelligent analysis of health data and intelligent system can never replace cardiologists. It can only act as a helpful tool for the cardiologist’s decisions making. PMID:25395730

  16. Reduced Data Dualscale Entropy Analysis of HRV Signals for Improved Congestive Heart Failure Detection

    NASA Astrophysics Data System (ADS)

    Kuntamalla, Srinivas; Lekkala, Ram Gopal Reddy

    2014-10-01

    Heart rate variability (HRV) is an important dynamic variable of the cardiovascular system, which operates on multiple time scales. In this study, Multiscale entropy (MSE) analysis is applied to HRV signals taken from Physiobank to discriminate Congestive Heart Failure (CHF) patients from healthy young and elderly subjects. The discrimination power of the MSE method is decreased as the amount of the data reduces and the lowest amount of the data at which there is a clear discrimination between CHF and normal subjects is found to be 4000 samples. Further, this method failed to discriminate CHF from healthy elderly subjects. In view of this, the Reduced Data Dualscale Entropy Analysis method is proposed to reduce the data size required (as low as 500 samples) for clearly discriminating the CHF patients from young and elderly subjects with only two scales. Further, an easy to interpret index is derived using this new approach for the diagnosis of CHF. This index shows 100 % accuracy and correlates well with the pathophysiology of heart failure.

  17. Analysis of Crossovers in the Interbeat Sequences of Elderly Individuals and Heart Failure Patients

    NASA Astrophysics Data System (ADS)

    Muñoz-Diosdado, A.; del Río Correa, J. L.

    2006-09-01

    Many physical and biological systems exhibit complex behavior characterized by long-range power-law correlations. Detrended fluctuation analysis (DFA) is a scaling analysis method that provides a scaling parameter to represent the correlation properties of a signal. The study of interbeat sequences with the DFA method has revealed the presence of crossovers associated with physiological aging and heart with failure; the hinges present in the crossover region from both the elderly healthy individuals and the patients with congestive heart failure (CHF) are in opposite directions. The interbeat sequences of healthy young persons do not show crossovers. In this paper we study interbeat time series of healthy young and elderly persons and patients with CHF. We use the DFA-m method, where m refers to the order of the polynomial function used for the fitting. For instance, DFA-2 filters linear trends and DFA-3 filters quadratic trends. We found that the presence of the crossovers and the direction of the hinges are conserved when we apply the DFA method for different values of m. Therefore we conclude that the DFA-m method is a reliable method to accurately quantify correlations in interbeat time series even if there are polynomial trends. We can characterize the crossovers and we can conclude that the crossovers are not a result of the trends; they are part of the system dynamics.

  18. Multiscale Failure Analysis of Laminated Composite Panels Subjected to Blast Loading Using FEAMAC/Explicit

    NASA Technical Reports Server (NTRS)

    Pineda, Evan J.; Waas, Anthony M.; Berdnarcyk, Brett A.; Arnold, Steven M.; Collier, Craig S.

    2009-01-01

    This preliminary report demonstrates the capabilities of the recently developed software implementation that links the Generalized Method of Cells to explicit finite element analysis by extending a previous development which tied the generalized method of cells to implicit finite elements. The multiscale framework, which uses explicit finite elements at the global-scale and the generalized method of cells at the microscale is detailed. This implementation is suitable for both dynamic mechanics problems and static problems exhibiting drastic and sudden changes in material properties, which often encounter convergence issues with commercial implicit solvers. Progressive failure analysis of stiffened and un-stiffened fiber-reinforced laminates subjected to normal blast pressure loads was performed and is used to demonstrate the capabilities of this framework. The focus of this report is to document the development of the software implementation; thus, no comparison between the results of the models and experimental data is drawn. However, the validity of the results are assessed qualitatively through the observation of failure paths, stress contours, and the distribution of system energies.

  19. A critical analysis of the failure of nurses to raise concerns about poor patient care.

    PubMed

    Roberts, Marc

    2016-10-28

    The occurrence of poor patient care is emerging as one of the most significant, challenging, and critical issues confronting contemporary nursing and those responsible for the provision of health care more generally. Indeed, as a consequence of the increased recognition of the manner in which nurses can be implicated in the occurrence of poor patient care, there has been sustained critical debate that seeks to understand how such healthcare failings can occur and, in particular, why nurses seemingly fail to intervene, raise concerns, and effectively respond to prevent the occurrence and continuation of such poor patient care. In seeking to contribute to this critical discussion, and in contrast to those "situational explanations" that maintain that the failure to raise concerns is a consequence of the contextual factors and challenging conditions to which nurses can be subject in the clinical setting, this paper will provide a resolutely philosophical analysis of that failure. In particular, it will draw upon the work of Jean-Paul Sartre-the French philosopher generally regarded as one of the most influential thinkers of the twentieth century-in order to propose that his work can be productively recontextualized to provide a detailed, challenging, and provocative critical analysis of the occurrence and continuation of poor patient care and the role of individual nurse practitioners in such healthcare failings.

  20. Risk management for outsourcing biomedical waste disposal – Using the failure mode and effects analysis

    SciTech Connect

    Liao, Ching-Jong; Ho, Chao Chung

    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.

  1. SU-E-T-627: Failure Modes and Effect Analysis for Monthly Quality Assurance of Linear Accelerator

    SciTech Connect

    Xie, J; Xiao, Y; Wang, J; Peng, J; Lu, S; Hu, W

    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.

  2. Intergranular corrosion-fatigue failure of cobalt-alloy femoral stems. A failure analysis of two implants.

    PubMed

    Gilbert, J L; Buckley, C A; Jacobs, J J; Bertin, K C; Zernich, M R

    1994-01-01

    Two modular hip implants with a cobalt-alloy head and a cobalt-alloy stem were retrieved after a fracture had occurred in the neck region of the femoral component, eighty-five and seventy months after implantation. Both implants failed less than one millimeter distal to the taper junction between the head and the stem (outside of the taper). The fracture surfaces of the implant were investigated with the use of scanning electron microscopy, to determine the nature of the failure process. The fractures occurred at the grain boundaries of the microstructure and appeared to be the result of three factors: porosity at the grain boundaries; intergranular corrosive attack, initiated both at the head-neck taper and at the free surface; and cyclic fatigue-loading of the stem. The corrosive attack of the free surface was initiated, in part, by the egression of surface grains and by the ingression of fluid into the intergranular regions. Sectioned surfaces showed extensive intergranular corrosive attack in the prosthetic neck localized in the region of the head-neck taper junction and penetrating deeply into the microstructure.

  3. Error Patterns Analysis of Hearing Aid and Cochlear Implant Users as a Function of Noise

    PubMed Central

    Chun, Hyungi; Ma, Sunmi; Chun, Youngmyoung

    2015-01-01

    Background and Objectives Not all impaired listeners may have the same speech perception ability although they will have similar pure-tone threshold and configuration. For this reason, the present study analyzes error patterns in the hearing-impaired compared to normal hearing (NH) listeners as a function of signal-to-noise ratio (SNR). Subjects and Methods Forty-four adults participated: 10 listeners with NH, 20 hearing aids (HA) users and 14 cochlear implants (CI) users. The Korean standardized monosyllables were presented as the stimuli in quiet and three different SNRs. Total error patterns were classified into types of substitution, omission, addition, fail, and no response, using stacked bar plots. Results Total error percent for the three groups significantly increased as the SNRs decreased. For error pattern analysis, the NH group showed substitution errors dominantly regardless of the SNRs compared to the other groups. Both the HA and CI groups had substitution errors that declined, while no response errors appeared as the SNRs increased. The CI group was characterized by lower substitution and higher fail errors than did the HA group. Substitutions of initial and final phonemes in the HA and CI groups were limited by place of articulation errors. However, the HA group had missed consonant place cues, such as formant transitions and stop consonant bursts, whereas the CI group usually had limited confusions of nasal consonants with low frequency characteristics. Interestingly, all three groups showed /k/ addition in the final phoneme, a trend that magnified as noise increased. Conclusions The HA and CI groups had their unique error patterns even though the aided thresholds of the two groups were similar. We expect that the results of this study will focus on high error patterns in auditory training of hearing-impaired listeners, resulting in reducing those errors and improving their speech perception ability. PMID:26771013

  4. Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes

    SciTech Connect

    Huang, Jun-Lin; Zhou, Ke-Yi Xu, Jian-Qun; Wang, Xin-Meng; Tu, Yi-You

    2014-07-28

    Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.

  5. Acoustic emission analysis on tensile failure of steam-side oxide scales formed on T22 alloy superheater tubes

    NASA Astrophysics Data System (ADS)

    Huang, Jun-Lin; Zhou, Ke-Yi; Wang, Xin-Meng; Tu, Yi-You; Xu, Jian-Qun

    2014-07-01

    Failure of steam-side oxide scales on boiler tubes can seriously influence the safety of coal-fired power plants. Uniaxial tensile tests employing acoustic emission (AE) monitoring were performed, in this work, to investigate the failure behavior of steam-side oxide scales on T22 alloy boiler superheater tubes. The characteristic frequency spectra of the captured AE signals were obtained by performing fast Fourier transform. Three distinct peak frequency bands, 100-170, 175-250, and 280-390 kHz, encountered in different testing stages were identified in the frequency spectra, which were confirmed to, respectively, correspond to substrate plastic deformation, oxide vertical cracking, and oxide spalling with the aid of scanning electronic microscopy observations, and can thus be used for distinguishing different oxide failure mechanisms. Finally, the critical cracking strain of the oxide scale and the interfacial shear strength of the oxide/substrate interface were estimated, which are the critical parameters urgently desired for modeling the failure behavior of steam-side oxide scales on boiler tubes of coal-fired power plants.

  6. Multinational assessment of accuracy of equations for predicting risk of kidney failure: a meta-analysis

    PubMed Central

    Tangri, Navdeep; Grams, Morgan E.; Levey, Andrew S.; Coresh, Josef; Appel, Lawrence; Astor, Brad C.; Chodick, Gabriel; Collins, Allan J.; Djurdjev, Ognjenka; Elley, C. Raina; Evans, Marie; Garg, Amit X.; Hallan, Stein I.; Inker, Lesley; Ito, Sadayoshi; Jee, Sun Ha; Kovesdy, Csaba P.; Kronenberg, Florian; Lambers Heerspink, Hiddo J.; Marks, Angharad; Nadkarni, Girish N.; Navaneethan, Sankar D.; Nelson, Robert G.; Titze, Stephanie; Sarnak, Mark J.; Stengel, Benedicte; Woodward, Mark; Iseki, Kunitoshi

    2016-01-01

    Importance Identifying patients at risk of chronic kidney disease (CKD) progression may facilitate more optimal nephrology care. Kidney failure risk equations (KFREs) were previously developed and validated in two Canadian cohorts. Validation in other regions and in CKD populations not under the care of a nephrologist is needed. Objective To evaluate the accuracy of the KFREs across different geographic regions and patient populations through individual-participant data meta-analysis. Data Sources Thirty-one cohorts, including 721,357 participants with CKD Stages 3–5 in over 30 countries spanning 4 continents, were studied. These cohorts collected data from 1982 through 2014. Study Selection Cohorts participating in the CKD Prognosis Consortium with data on end-stage renal disease. Data Extraction and Synthesis Data were obtained and statistical analyses were performed between July 2012 and June 2015. Using the risk factors from the original KFREs, cohort-specific hazard ratios were estimated, and combined in meta-analysis to form new “pooled” KFREs. Original and pooled equation performance was compared, and the need for regional calibration factors was assessed. Main Outcome and Measure Kidney failure (treatment by dialysis or kidney transplantation). Results During a median follow-up of 4 years, 23,829 cases of kidney failure were observed. The original KFREs achieved excellent discrimination (ability to differentiate those who developed kidney failure from those who did not) across all cohorts (overall C statistic, 0.90 (95% CI 0.89–0.92) at 2 years and 0.88 (95% CI 0.86–0.90) at 5 years); discrimination in subgroups by age, race, and diabetes status was similar. There was no improvement with the pooled equations. Calibration (the difference between observed and predicted risk) was adequate in North American cohorts, but the original KFREs overestimated risk in some non-North American cohorts. Addition of a calibration factor that lowered the baseline

  7. Failure analysis of satellite subsystems to define suitable de-orbit devices

    NASA Astrophysics Data System (ADS)

    Palla, Chiara; Peroni, Moreno; Kingston, Jennifer

    2016-11-01

    Space missions in Low Earth Orbit (LEO) are severely affected by the build-up of orbital debris. A key practice, to be compliant with IADC (Inter-Agency Space Debris Coordination Committee) mitigation guidelines, is the removal of space systems that interfere with the LEO region not later than 25 years after the End of Mission. It is important to note that the current guidelines are not generally legally binding, even if different Space Agencies are now looking at the compliance for their missions. If the guidelines will change in law, it will be mandatory to have a postmission disposal strategy for all satellites, including micro and smaller classes. A potential increased number of these satellites is confirmed by different projections, in particular in the commercial sector. Micro and smaller spacecraft are, in general, not provided with propulsion capabilities to achieve a controlled re-entry, so they need different de-orbit disposal methods. When considering the utility of different debris mitigation methods, it is useful to understand which spacecraft subsystems are most likely to fail and how this may affect the operation of a de-orbit system. This also helps the consideration of which components are the most relevant or should be redundant depending on the satellite mass class. This work is based on a sample of LEO and MEO satellites launched between January 2000 and December 2014 with mass lower than 1000 kg. Failure analysis of satellite subsystems is performed by means of the Kaplan-Meier survival analysis; the parametric fits are conducted with Weibull distributions. The study is carried out by using the satellite database SpaceTrak™ which provides anomalies, failures, and trends information for spacecraft subsystems and launch vehicles. The database identifies five states for each satellite subsystem: three degraded states, one fully operational state, and one failed state (complete failure). The results obtained can guide the identification of the

  8. Characterization and Failure Analysis of Ceramic Filters Utilized for Emission Control Coal Gasification

    SciTech Connect

    Daniel Mei; Jianren Zhou; Ziaul Huque

    1998-03-01

    Advanced integrated gasification combined cycle (IGCC) and pressurized fluidized bed combustion (PFBC) power system requires both hot gas desulfurization and particulate filtration to improve system thermal efficiency and overall performance. Therefore, effective high temperature ceramic filters are indispensable key component in both of the advanced IGCC and PFBC coal based power systems to perform hot gas cleanup work. To meet the environmental particulate emission requirements and improve thermal efficiency, ceramic filters are mainly utilized to cleanup the hot gas particulate to protect downstream heat exchanger and gas turbine components from fouling and corrosion. The mechanical integrity of ceramic filters and an efficient dust cake removal system are the key issues for hot gas cleanup systems. The filters must survive combined stresses due to mechanical, thermal, chemical and steam attack throughout normal operations (cold back pulse cleaning jets), unexpected excessive ash accumulation, and the start up and shut down conditions. To evaluate the design and performance of ceramic filters, different long term filter testing programs were conducted. To fulfill this purpose, two Advanced Particle Filter (APF) systems were complete at Tidd PFBC Demonstration Plant, in Brilliant, Ohio in late 1990 as part of the Department of Energy's (DOE) Clean Coal Technology Program. But the most undesirable thing ever happened was the sudden functional and physical failures of filters prior to its designed life time. In Tidd APF filter vessel, twenty eight (28) filters failed one time. Significant research effort has been carried out to find out the causes that led to the early failure of filters. In this work, the studies are emphasized on the possible failure causes analysis of rigid ceramic candle filters. The objectives of this program were to provide an systematic study on the characterization of filters, material laboratory analysis on filter micro-structure, the dust

  9. Failure Analysis of Fractured Poppet from Space Shuttle Orbiter Flow Control Valve

    NASA Technical Reports Server (NTRS)

    Russell, Richard

    2010-01-01

    This slide presentation reviews the failure analysis of a fractured poppet from a flow control valve (FCV) used on the space shuttle. This presentation has focused on the laboratory analysis of the failed hardware. The use of Scanning electron fractography during the investigation led to the conclusion that the poppet failed due to fatigue cracking that, most likely, occurred under changing loading conditions. The initial investigation led to a more thorough test of poppets that had been retired, this testing led to the conclusion that the thumbnail cracks in the flight hardware had existed for the life of the shuttle program. This led to a program to develop an eddy current technique that was capable of detecting small very tight cracks.

  10. Analysis of roof and pillar failure associated with weak floor at a limestone mine

    PubMed Central

    Murphy, Michael M.; Ellenberger, John L.; Esterhuizen, Gabriel S.; Miller, Tim

    2016-01-01

    A limestone mine in Ohio has had instability problems that have led to massive roof falls extending to the surface. This study focuses on the role that weak, moisture-sensitive floor has in the instability issues. Previous NIOSH research related to this subject did not include analysis for weak floor or weak bands and recommended that when such issues arise they should be investigated further using a more advanced analysis. Therefore, to further investigate the observed instability occurring on a large scale at the Ohio mine, FLAC3D numerical models were employed to demonstrate the effect that a weak floor has on roof and pillar stability. This case study will provide important information to limestone mine operators regarding the impact of weak floor causing the potential for roof collapse, pillar failure, and subsequent subsidence of the ground surface. PMID:27088041

  11. 78 FR 46949 - Essentia Natural Memory Foam Company, Inc.; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ... Essentia Natural Memory Foam Company, Inc.; Analysis of Proposed Consent Order to Aid Public Comment AGENCY... accepted, subject to final approval, an agreement containing a consent order from Essentia Natural Memory... marketing and sale of memory foam mattresses. According to the FTC's complaint, respondent represented...

  12. 78 FR 2398 - Motorola Mobility LLC and Google Inc.; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-01-11

    ...The consent agreement in this matter settles alleged violations of federal law prohibiting unfair or deceptive acts or practices or unfair methods of competition. The attached Analysis of Proposed Consent Order to Aid Public Comment describes both the allegations in the draft complaint and the terms of the consent order-- embodied in the consent agreement--that would settle these...

  13. 75 FR 42752 - Nestle' HealthCare Nutrition, Inc.; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-22

    ... Nestle' HealthCare Nutrition, Inc.; Analysis of Proposed Consent Order to Aid Public Comment AGENCY..., subject to final approval, an agreement containing a consent order from Nestle; HealthCare Nutrition, Inc... number. Comments also should not include any sensitive health information, such as medical records...

  14. 75 FR 61141 - In the Matter of The Coca-Cola Company; Analysis of Agreement Containing Consent Order to Aid...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-04

    ... the Matter of The Coca-Cola Company; Analysis of Agreement Containing Consent Order to Aid Public... written comments electronically or in paper form. Comments should refer to ``The Coca- Cola Company, File... by using the following weblink: ( https://ftcpublic.commentworks.com/ftc/coca-cola ) and...

  15. Public Discourse on HIV and AIDS: An Archival Analysis of National Newspaper Reporting in Uganda, 1996-2011

    ERIC Educational Resources Information Center

    Lagone, Elizabeth; Mathur, Sanyukta; Nakyanjo, Neema; Nalugoda, Fred; Santelli, John

    2014-01-01

    Uganda is recognised as an early success story in the HIV epidemic at least in part due to an open and vigorous national dialogue about HIV prevention. This study examined the national discourse about HIV, AIDS, and young people in New Vision, Uganda's leading national newspaper between 1996 and 2011, building from a previous archival analysis of…

  16. 78 FR 75350 - Goldenshores Technologies, LLC and Erik M. Geidl; Analysis of Proposed Consent Order To Aid...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-12-11

    ... Goldenshores Technologies, LLC and Erik M. Geidl; Analysis of Proposed Consent Order To Aid Public Comment... Social Security number, date of birth, driver's license number or other state identification number or... Commission is subject to delay due to heightened security screening. As a result, we encourage you to...

  17. 77 FR 35391 - Franklin Budget Car Sales, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-13

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION Franklin Budget Car Sales, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal... Budget Car Sales, Inc., also doing business as Franklin Toyota/Scion (``Franklin Toyota''). The...

  18. Bioimpedance analysis and plasma B-type natriuretic peptide assay may cooperate in diagnosing and managing heart failure.

    PubMed

    Tamagno, Gianluca; Guzzon, Samuele

    2006-06-01

    We describe the case of an obese patient presenting leg oedema, progressive oliguria, orthopnoea and mild increased B-type natriuretic peptide (BNP) levels. Bioimpedance analysis (BIA) provided additional data for the interpretation of the plasma BNP values, contributing to the diagnosis of heart failure and the appropriate management of the patient. In our mind, BIA could represent a useful tool for integrating the plasma BNP assay in both diagnosis and management of heart failure.

  19. HIV / AIDS

    MedlinePlus

    ... facebook share with twitter share with linkedin HIV/AIDS HIV, or human immunodeficiency virus, is the virus ... HIV/AIDS. Why Is the Study of HIV/AIDS a Priority for NIAID? Nearly 37 million people ...

  20. Hearing Aids

    MedlinePlus

    ... and Consumer Devices Consumer Products Hearing Aids Hearing Aids Share Tweet Linkedin Pin it More sharing options ... to restrict your daily activities. Properly fitted hearing aids and aural rehabilitation (techniques used to identify and ...