Science.gov

Sample records for aided failure analysis

  1. Efficient computer-aided failure analysis of integrated circuits using scanning electron microscopy

    NASA Astrophysics Data System (ADS)

    Propst, R. H.; Oxford, W. V.

    1985-12-01

    A working, operational system for computer-aided failure analysis of integrated circuits using a scanning electron microscope (SEM) is described. Statistical data analysis and image-processing algorithms are applied to digitized SEM image data. Faults are automatically identified and characterized at the single transistor level. Data-storage requirements for locating and characterizing semiconductor device failures are evaluated. A working, operational methods is presented which minimizes these requirements, increases throughput, and permits a high degree of automation.

  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. 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.

  5. Failure Analysis for Improved Reliability

    NASA Technical Reports Server (NTRS)

    Sood, Bhanu

    2016-01-01

    Outline: Section 1 - What is reliability and root cause? Section 2 - Overview of failure mechanisms. Section 3 - Failure analysis techniques (1. Non destructive analysis techniques, 2. Destructive Analysis, 3. Materials Characterization). Section 4 - Summary and Closure

  6. 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…

  7. Analysis of a Memory Device Failure

    NASA Technical Reports Server (NTRS)

    Nicolas, David P.; Devaney, John; Gores, Mark; Dicken, Howard

    1998-01-01

    The recent failure of a vintage memory device presented a unique challenge to failure analysts. Normally device layouts, fabrication parameters and other technical information were available to assist the analyst in the analysis. However, this device was out of production for many years and the manufacturer was no longer in business, so the information was not available. To further complicate this analysis, the package leads were all but removed making additional electrical testing difficult. Under these conditions, new and innovative methods were used to analyze the failure. The external visual exam, radiography, PIND, and leak testing were performed with nominal results. Since electrical testing was precluded by the short lead lengths, the device was delidded to expose the internal structures for microscopic examination. No failure mechanism was identified. The available electrical data suggested an ESD or low level EOS type mechanism which left no visible surface damage. Due to parallel electrical paths, electrical probing on the chip failed to locate the failure site. Two non-destructive Scanning Electron Microscopy techniques, CIVA (Charge Induced Voltage Alteration) and EBIC (Electron Beam Induced Current), and a liquid crystal decoration technique which detects localized heating were employed to aid in the analysis. CIVA and EBIC isolated two faults in the input circuitry, and the liquid crystal technique further localized two hot spots in regions on two input gates. Removal of the glassivation and metallization revealed multiple failure sites located in the gate oxide of two input transistors suggesting machine (testing) induced damage.

  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. Failure rate analysis using GLIMMIX

    SciTech Connect

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

    1998-12-01

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

  12. 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).

  13. 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.

  14. Integrated Circuit Failure Analysis Hypertext Help System

    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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. The advent of failure analysis software technology

    SciTech Connect

    Henderson, C.L.; Barnard, R.D.

    1994-02-01

    The increasing complexity of integrated circuits demands that software tools, in addition to hardware tools, be used for successful diagnosis of failure. A series of customizable software tools have been developed that organize failure analysis information and provide expert level help to failure analysts to increase their productivity and success.

  20. 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.

  1. 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.

  2. Program Helps In Analysis Of Failures

    NASA Technical Reports Server (NTRS)

    Stevenson, R. W.; Austin, M. E.; Miller, J. G.

    1993-01-01

    Failure Environment Analysis Tool (FEAT) computer program developed to enable people to see and better understand effects of failures in system. User selects failures from either engineering schematic diagrams or digraph-model graphics, and effects or potential causes of failures highlighted in color on same schematic-diagram or digraph representation. Uses digraph models to answer two questions: What will happen to system if set of failure events occurs? and What are possible causes of set of selected failures? Helps design reviewers understand exactly what redundancies built into system and where there is need to protect weak parts of system or remove them by redesign. Program also useful in operations, where it helps identify causes of failure after they occur. FEAT reduces costs of evaluation of designs, training, and learning how failures propagate through system. Written using Macintosh Programmers Workshop C v3.1. Can be linked with CLIPS 5.0 (MSC-21927, available from COSMIC).

  3. Failure analysis issues in microelectromechanical systems (MEMS).

    SciTech Connect

    Walraven, Jeremy Allen

    2005-07-01

    Failure analysis and device characterization of MEMS components are critical steps in understanding the root causes of failure and improving device performance. At the wafer and die level these tasks can be performed with little or no sample preparation. Larger challenges occur after fabrication when the device is packaged, capped, sealed, or otherwise obstructed from view. The challenges and issues of MEMS failure analysis lie in identifying the root cause of failure for these packaged, capped, and sealed devices without perturbing the device or its immediate environment. Novel methods of gaining access to the device or preparing the device for analysis are crucial to accurately determining the root cause of failure. This paper will discuss issues identified in performing root cause failure analysis of packaged MEMS devices, as well as the methods employed to analyze them.

  4. FEAT - FAILURE ENVIRONMENT ANALYSIS TOOL (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Pack, G.

    1994-01-01

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

  5. FEAT - FAILURE ENVIRONMENT ANALYSIS TOOL (UNIX VERSION)

    NASA Technical Reports Server (NTRS)

    Pack, G.

    1994-01-01

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

  6. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1992-12-31

    This paper presents results from a study to analyze the performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, structural finite element analysis, and detailed failure data collection. Metallography demonstrated that microstructure of steel bar stock needs to be considered. Current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding. Finite element analysis of the threaded connection identifies stress and fatigue concentrations and quantitatively assesses the performance and failure of coupling designs under a variety of loading conditions. Subcritical fractures observed in the metallography are also suggested by the calculated stress distribution in the threaded coupling. Failure data illustrates both magnitude and frequency of the failures, as well as categorizing the suspected cause of failure. This failure information alone can reduce failures by indicating specific problem areas. These results are expected to yield improved choice of metal bar stock, thread design, and make-up practices which can reduce sucker rod failures.

  7. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1992-01-01

    This paper presents results from a study to analyze the performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, structural finite element analysis, and detailed failure data collection. Metallography demonstrated that microstructure of steel bar stock needs to be considered. Current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding. Finite element analysis of the threaded connection identifies stress and fatigue concentrations and quantitatively assesses the performance and failure of coupling designs under a variety of loading conditions. Subcritical fractures observed in the metallography are also suggested by the calculated stress distribution in the threaded coupling. Failure data illustrates both magnitude and frequency of the failures, as well as categorizing the suspected cause of failure. This failure information alone can reduce failures by indicating specific problem areas. These results are expected to yield improved choice of metal bar stock, thread design, and make-up practices which can reduce sucker rod failures.

  8. AIDS in Haiti: a bibliometric analysis

    PubMed Central

    Macias-Chapula, César A.

    2000-01-01

    Objectives: In Haiti, AIDS has become the leading cause of death in sexually active adults. Increasingly, AIDS has become a disease of women and children. Previous bibliometric studies have shown the emergence of Haiti as a leading country in the production of AIDS literature in the Latin American and Caribbean regions. No information exists, however, regarding the type of publications produced, the collaboration patterns used, or the subject content analysis of this production. The purpose of this study was to gain insight into the construction of this literature production. Methods: A bibliometric analysis regarding Haitian AIDS research was conducted in the AIDSLINE database for the period 1980 to 1998. An attempt was made to identify the patterns of the growth in AIDS literature, as well as the types of documents published, authorship, institutional affiliations of authors, and subject content. Results: Results indicated that most documents were published in periodicals. The International Conference on AIDS obtained the highest frequency. The United States, Haiti, and Canada were the main productive countries. Conclusions: While nearly 40% of the records corresponded to ethnology-related articles, HIV infections, sex behavior, pregnancy, and substance-related disorders headed the Medical Subject Headings (MeSH) found. Main aspects of AIDS papers focused on epidemiology, complications, and trends issues. PMID:10658964

  9. 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.

  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. 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.

  12. Analysis of sucker rod and sinkerbar failures

    SciTech Connect

    Waggoner, J.R.; Buchheit, R.G.

    1993-03-01

    This report presents results of a study of performance and failures of the sucker rod/sinkerbar string used in beam-pumping operations through metallography, finite element analysis, and failure data collection. Metallography showed that the microstructure of the steel bar stock needs to be considered to improve the fatigue resistance of the sucker rod strings. The current specification based on tensile strength, or yield strength, may not be appropriate since failure occurs because of fatigue and not yielding, and tensile strength is not always a good measure of fatigue resistance. Finite element analysis of the threaded connection quantitatively assesses the coupling designs under various loading conditions. Subcritical fractures in metallography are also suggested by calculated stress distribution in threaded coupling. Failure data illustrates both magnitude and frequency of failures, as well as categorizing the suspected cause of failure. Application of the results in each of these project areas is expected to yield improved choice of metal bar stock, thread design, and make-up practices which can significantly reduce the frequency of sucker rod failures. Sucker rod failures today are not inherent in the process, but can be minimized through the application of new technology and observation of common-sense practices.

  13. 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…

  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. 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.

  16. Computer aided analysis of phonocardiogram.

    PubMed

    Singh, J; Anand, R S

    2007-01-01

    In the present paper analysis of phonocardiogram (PCG) records are presented. The analysis has been carried out in both time and frequency domains with the aim of detecting certain correlations between the time and frequency domain representations of PCG. The analysis is limited to first and second heart sounds (S1 and S2) only. In the time domain analysis the moving window averaging technique is used to determine the occurrence of S1 and S2, which helps in determination of cardiac interval and absolute and relative time duration of individual S1 and S2, as well as absolute and relative duration between them. In the frequency domain, fast Fourier transform (FFT) of the complete PCG record, and short time Fourier transform (STFT) and wavelet transform of individual heart sounds have been carried out. The frequency domain analysis gives an idea about the dominant frequency components in individual records and frequency spectrum of individual heart sounds. A comparative observation on both the analyses gives some correlation between time domain and frequency domain representations of PCG. PMID:17701776

  17. On Automating Failure Mode Analysis and Enforcing its Integrity

    NASA Technical Reports Server (NTRS)

    Tai, Ann T.; Tso, Kam S.; Chau, Savio N.

    2005-01-01

    This paper reports our experience on the development of a design-for-safety (DFS) workbench called Risk Assessment and Management Environment (RAME) for microelectronic avionics systems. Our objective is to transform DFS practice from an ad-hoc, inefficient, error-prone approach to a stringent engineering process such that DFS can keep up with the rapidly growing complexity of avionics systems. In particular, RAME is built upon an information infrastructure that comprises a fault model, a knowledge base, and a failure reporting/tracking system. This infrastructure permits systematic learning from prior projects and enables the automation of failure modes, effects and criticality analysis (FMECA). Among other unique features, the most important advantage of RAME is its capability of directly accepting design source code in hardware description languages (HDLs) for automated failure mode analysis, which enables RAME to be compatible and to evolve with most electronic-computer-aided-design systems. Through an initial experimental evaluation of the RAME prototype, we show that our approach to FMECA automation improves failure mode analysis turn-around-time, completeness, and accuracy.

  18. 75 FR 45114 - Rite Aid Corporation; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-02

    ... Rite Aid Corporation; Analysis of Proposed Consent Order to Aid Public Comment AGENCY: Federal Trade... competition. The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint... invited to submit written comments electronically or in paper form. Comments should refer to ``Rite...

  19. 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.

  20. 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.

  1. Failure analysis of brass tubes

    SciTech Connect

    Lawrence, S.J.; Bodnar, R.L.

    1997-02-01

    The 1996 Jacquet Lucas Award for Excellence in Metallography was won by Samuel J. Lawrence and Richard L. Bodnar for their analysis of cracks in Admiralty brass cooling tubes, which are part of a heat exchanger in a turbogenerator that provides electricity to a manufacturing plant. A mixture of non-recirculating city and spring pit water flows through bundles of tubes to cool the oil in which they are immersed. However, a problem developed when several of the brass tubes cracked transversely, allowing cooling water to mix with the oil. This award-winning entry in the ASM/IMS competition shows how the metallographers analyzed the cracks, and what the results were.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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

    This report discusses research 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 burnup, 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-PF1/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 burnup. Using peaking factors commensurate with actual burnups would result in longer intervals for both reactor designs. This document provides appendices K and L of this report which provide plots for the timing analysis of PWR fuel pin failures for Oconee and Seabrook respectively.

  7. 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…

  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. Using capillary electrophoresis for failure analysis

    SciTech Connect

    Kelly, R.G.; Scully, H.S.; Stoner, G.E. . Center for Electrochemical Science and Engineering)

    1993-07-01

    Capillary electrophoresis (CE), an advanced solution analysis technique, can be used for failure analysis of corroded components. It has high sensitivity (concentrations as low as parts-per-trillion) and can detect quantitatively a large number of ionic species. CE determined the vapor-phase attack by organic acids, mainly acetic acid, on an electrical equipment enclosure. These acids most likely originated from the seasoning of the oak pallets used to transport the manufactured items, accumulating inside the shrink-wrap film used to bind packages to the pallet.

  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. Probabilistic Computational Methods in Structural Failure Analysis

    NASA Astrophysics Data System (ADS)

    Krejsa, Martin; Kralik, Juraj

    2015-12-01

    Probabilistic methods are used in engineering where a computational model contains random variables. Each random variable in the probabilistic calculations contains uncertainties. Typical sources of uncertainties are properties of the material and production and/or assembly inaccuracies in the geometry or the environment where the structure should be located. The paper is focused on methods for the calculations of failure probabilities in structural failure and reliability analysis with special attention on newly developed probabilistic method: Direct Optimized Probabilistic Calculation (DOProC), which is highly efficient in terms of calculation time and the accuracy of the solution. The novelty of the proposed method lies in an optimized numerical integration that does not require any simulation technique. The algorithm has been implemented in mentioned software applications, and has been used several times in probabilistic tasks and probabilistic reliability assessments.

  12. J series thruster isolator failure analysis

    NASA Technical Reports Server (NTRS)

    Campbell, J. W.; Bechtel, R. T.; Brophy, J. R.

    1982-01-01

    Three Hg propellant isolators (two cathode and one main) failed during testing in the Mission Profile Life Test. These failures involved contamination of the surface of the alumina insulating body which resulted in heating of the vaporizer by leakage current from the high voltage supply, with subsequent loss of propellant flow rate control. Failure analysis of the isolators showed the surface resistance was temperature dependent and that the alumina could be restored to its original insulating state by grit blasting the surface. The contaminant was identified as carbon and the most likely sources identified as ambient facility hydrocarbons, directed back-sputtered facility materials, and outgassing from organic insulating materials within the thruster envelope. Methods to eliminate contamination from each of these sources are described.

  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. 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.

  15. Analysis of reciprocating compressor piston rod failures

    SciTech Connect

    Tripp, H.A.; Drosjack, M.J.

    1984-02-01

    This report presents the analysis of five piston rod failures which occurred on reciprocating compressors. Calculations are shown for rod stress which includes nominal rod loading sources as well as additional loads due to unusual pressure losses in the compressor valves, flexure of the rods due to misalignment, and manufacturing errors. The additional loads were incorporated on the basis of field measurements. The stress values are used with Baquin's equation to produce fatigue life curves for the rods. Based on the calculations, recommendations for modified rods were made. The calculation procedures are described in a manner which will permit their application to other reciprocating compressors.

  16. Integrated Circuit Failure Analysis Expert System

    1995-10-03

    The software assists a failure analyst performing failure anaysis on intergrated 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.

  17. 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.

  18. Initial Failure Analysis of Ceramic Filters

    SciTech Connect

    Huque, Z.; Mei, D.; Zhou, J.

    1996-12-31

    Effective high temperature ceramic filters are indispensable in the advanced, coal based power systems (IGCC and PFBC). To meet the environmental particulate emission requirements and improve thermal efficiency, ceramic filters are 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. However, many filter failures 1649 were reported prior to its desired life time. In Tidd APF vessel, 28 filters failed one time, The objectives of this program were to provide an understanding of the factors pertinent to the failures of ceramic filters by characterizing filter properties and the dust cake removal mechanism, Researches were emphasized on understanding of changes of filter properties and back pulse cleaning mechanism to resolve the issues relating to filter permeability variations, ash bridging and micro-thermal cracks induced during cold back pulse cleaning. To perform failure analysis of ceramic filters, thermal numerical simulation, material laboratory analysis on filter materials and dust cake, and measurements on filter properties and back pulse intensity along filter axis within a bench scale filter chamber were conducted.

  19. 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.

  20. 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

  1. Nonlinear and Failure Analysis of Composite Structures

    NASA Technical Reports Server (NTRS)

    Noor, Ahmed K.; Starnes, James H. (Technical Monitor)

    2002-01-01

    The overall goal of this research is to assess the effect of discontinuities and uncertainties on the nonlinear response and failure of stiffened composite panels subjected to combined mechanical and thermal loads. The key elements of the study are: (a) study of the effects of stiffener geometry and of transverse stresses on the response, damage initiation and propagation in stiffened composite panels; (b) use of hierarchical sensitivity coefficients to identify the major parameters that affect the response and damage in each of the different levels in the hierarchy (micromechanical, layer, panel, subcomponent and component levels); and, (c) application of fuzzy set techniques to identify the range and variation of possible responses. The computational models developed are used in conjunction with experiments to understand the physical phenomena associated with the nonlinear response and failure of stiffened composite panels. A toolkit is developed for use in conjunction with deterministic analysis programs to help the designer in assessing the effect of uncertainties in the different computational model parameters on the variability of the response quantities.

  2. Failure analysis of a burner shield

    SciTech Connect

    Copley, B.P.; Saunders, K.L.

    1997-03-01

    Alterations that improve the performance of equipment sometimes cause unexpected and undesirable side effects. At a California cogeneration facility, the burner shields in a heat-recovery steam generator were modified to improve burner emissions. The unintended result, however, was gross deformation of the shields, which interfered with combustion. This problem prompted a review of the original design geometry and operating history to identify the controlling parameters. A failure analysis was then performed for the modified design to find its key design and response features, particularly the ones causing the undesirable response of the critical component. A second modified design was then evaluated for all important loading conditions and critical failure mechanisms. The second modified design greatly reduced the sustained stress levels, but the safety margin was smaller than typically desired for components in this industry. Therefore, key locations were identified for inspection on a regular basis. Larger thermal loads than those used for evaluation purposes were observed in the field. When key components were re-evaluated for the new thermal load, the safety margins were significantly reduced. Although the initial performance has been very satisfactory, the geometry will be further refined.

  3. Failure Analysis and Quality Control of Microwave Devices

    NASA Astrophysics Data System (ADS)

    Ming, Zhimao; Zong, Bo; Bai, Xiaoshu

    2016-02-01

    Microwave devices have been widely used in the communication and navigation and navigation fields. The reliability level of microwave devices is an important factor to affect the reliability of electronic equipment. The statistical analysis for the failure of sixty microwave devices was presented and the main causes of failure were given. The failure is mainly analyzed from three aspects below, the surface failure mechanism, the interior failure mechanism and the failure mechanism of electrode system and encapsulation. The surface failure mechanism is analyzed from four aspects, ionic contamination on the surface, silicon dioxide layer defect, the influence of interface states between silicon and silicon dioxide, radiation ionization trap. The interior failure mechanism is analyzed from two aspects, failure caused by thermal breakdown and failure due to latch-up effect of integrated circuit. The failure mechanism of electrode system and encapsulation is analyzed from two aspects, failure mechanism of metallization system and failure mechanism of metallization system of bonding. Meanwhile, the results showed that operation, process, adjustment, components and using problems were the main causes of failure. The valuable statistical data and analysis results were provided for the quality control of microwave devices.

  4. Risk analysis. HIV / AIDS country profile: Senegal.

    PubMed

    1996-12-01

    Since the first acquired immunodeficiency syndrome (AIDS) case was confirmed in 1986, Senegal has conducted an aggressive prevention campaign. Senegal's National AIDS Committee has noted the contributions of poverty and migration to the spread of AIDS. By June 1994, 1297 AIDS cases had been reported and an estimated 500,000 people (1.4% of the population) were infected with human immunodeficiency virus (HIV)-1 and 2. The highest rate of HIV infection (14%) exists among commercial sex workers. At present, HIV/AIDS cases are concentrated in Dakar, Kaolack, the Matam region, and Ziguinchor; however, the growing importance of inter-regional trading is expected to spread HIV to the smaller towns and rural areas. Also salient is the recent devaluation by 50% of the CFA franc, which has reduced the public sector workforce and led many poor urban residents into commercial sex work. CFA devaluation has made Senegal attractive to tourists and business visitors--another factor responsible for growth of the legalized commercial sex industry. Although sex workers are instructed in condom use and tested annually for HIV, only 850 of the 2000 registered sex workers have reported for check-ups, and the majority of prostitutes are unregistered. Senegal's AIDS Plan for 1994-98 focuses on care of AIDS patients, pressures placed on family structures by HIV, and AIDS-related erosions in the status of women. Each health service region has its own local plan for AIDS/HIV and sexually transmitted diseases, supervised by a regional committee. Public education has involved outreach to religious leaders, promotion of affordable condoms, and distribution of over 75,000 leaflets to key target populations. About US $16 million of the $25,688,875-budget HIV/AIDS program for 1994-98 was pledged by external donors.

  5. Methods of the computer-aided statistical analysis of microcircuits

    NASA Astrophysics Data System (ADS)

    Beliakov, Iu. N.; Kurmaev, F. A.; Batalov, B. V.

    Methods that are currently used for the computer-aided statistical analysis of microcircuits at the design stage are summarized. In particular, attention is given to methods for solving problems in statistical analysis, statistical planning, and factorial model synthesis by means of irregular experimental design. Efficient ways of reducing the computer time required for statistical analysis and numerical methods of microcircuit analysis are proposed. The discussion also covers various aspects of the organization of computer-aided microcircuit modeling and analysis systems.

  6. 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.

  7. [HIV/AIDS in South Africa and Haiti: the failure of epidemic governance and achievement of the MDGs].

    PubMed

    Thelot, Fils-Lien Ely

    2009-01-01

    Since their adoption in 2000 by the United Nations, the Millennium Development Goals set for 2015 appear to have become a part of the policy agenda of all of the member states. Three of these eight objectives deal with health issues. "Combat HIV/AIDS, malaria and other diseases": this is the formulation of the sixth MDG. Observing that in many countries strongly affected by poverty and inequalities, the epidemic continues to spread, without really reversing at all, and that access to antiretrovirals is possible for only a small proportion of the patient who need them, we consider the problems of global governance in the field of health. Our intention is to explain that the failure to deal with the HIV/AIDS epidemic may constitute an obstacle to the achievement of the MDGs by 2015. Proposing a comprehensive sociology of HIV/AIDS, this article pays special attention to the dimension of the meaning of the disease, simultaneously as a policy issue, a social construction, and an object of study in the social sciences. Looking at the two countries most affected by the epidemic in Africa and in the Caribbean, we examine the different aspects that have determined the failure of governance and the effects of this failure on the populations concerned. The excessive conflictuality in South Africa and the biopolitics of "let them die" and the fragmentation of the networks involved in the combat in Haiti are considered to have contributed to a crisis in the epidemic's governance. In both cases, the consequences have been expressed by a reduced life expectancy, insufficient access to antiretroviral drugs, reinforcement of the socioeconomic inequalities of health, the production of new pockets of poverty, more fragile household and national economies, an increase in maternal and child mortality ... The failure of the governance of the HIV/AIDS epidemic in countries such as Haiti and South Africa appears to foretell the impossibility of achieving the MDGs by 2015. PMID:20185388

  8. 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

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

    NASA Technical Reports Server (NTRS)

    Nicolas, D. P.

    1974-01-01

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

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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…

  15. Risk analysis. HIV / AIDS country profile: Mozambique.

    PubMed

    1996-12-01

    Mozambique's National STD/AIDS Control Program (NACP) estimates that, at present, about 8% of the population is infected with human immunodeficiency virus (HIV). The epidemic is expected to peak in 1997. By 2001, Mozambique is projected to have 1,650,000 HIV-positive adults 15-49 years of age, of whom 500,000 will have developed acquired immunodeficiency syndrome (AIDS), and 500,000 AIDS orphans. Incidence rates are highest in the country's central region, the transport corridors, and urban centers. The rapid spread of HIV has been facilitated by extreme poverty, the social upheaval and erosion of traditional norms created by years of political conflict and civil war, destruction of the primary health care infrastructure, growth of the commercial sex work trade, and labor migration to and from neighboring countries with high HIV prevalence. Moreover, about 10% of the adult population suffers from sexually transmitted diseases (STDs), including genital ulcers. NACP, created in 1988, is attempting to curb the further spread of HIV through education aimed at changing high-risk behaviors and condom distribution to prevent STD transmission. Theater performances and radio/television programs are used to reach the large illiterate population. The integration of sex education and STD/AIDS information in the curricula of primary and secondary schools and universities has been approved by the Ministry of Education. Several private companies have been persuaded to distribute condoms to their employees. Finally, the confidentiality of HIV patients has been guaranteed. In 1993, the total AIDS budget was US $1.67 million, 50% of which was provided by the European Union. The European Commission seeks to develop a national strategy for managing STDs within the primary health care system.

  16. Risk analysis. HIV / AIDS country profile: Mozambique.

    PubMed

    1996-12-01

    Mozambique's National STD/AIDS Control Program (NACP) estimates that, at present, about 8% of the population is infected with human immunodeficiency virus (HIV). The epidemic is expected to peak in 1997. By 2001, Mozambique is projected to have 1,650,000 HIV-positive adults 15-49 years of age, of whom 500,000 will have developed acquired immunodeficiency syndrome (AIDS), and 500,000 AIDS orphans. Incidence rates are highest in the country's central region, the transport corridors, and urban centers. The rapid spread of HIV has been facilitated by extreme poverty, the social upheaval and erosion of traditional norms created by years of political conflict and civil war, destruction of the primary health care infrastructure, growth of the commercial sex work trade, and labor migration to and from neighboring countries with high HIV prevalence. Moreover, about 10% of the adult population suffers from sexually transmitted diseases (STDs), including genital ulcers. NACP, created in 1988, is attempting to curb the further spread of HIV through education aimed at changing high-risk behaviors and condom distribution to prevent STD transmission. Theater performances and radio/television programs are used to reach the large illiterate population. The integration of sex education and STD/AIDS information in the curricula of primary and secondary schools and universities has been approved by the Ministry of Education. Several private companies have been persuaded to distribute condoms to their employees. Finally, the confidentiality of HIV patients has been guaranteed. In 1993, the total AIDS budget was US $1.67 million, 50% of which was provided by the European Union. The European Commission seeks to develop a national strategy for managing STDs within the primary health care system. PMID:12320532

  17. 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.

  18. Reliability analysis based on the losses from failures.

    PubMed

    Todinov, M T

    2006-04-01

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

  19. High Fidelity Failure Analysis for a Composite Fuselage Section

    NASA Technical Reports Server (NTRS)

    Li, Jain; Davila, Carlos G.; Chen, Tzi-Kang

    2001-01-01

    A high fidelity delamination failure analysis was developed by combining a local failure analysis with a global full-scale finite element structural analysis to address strength and delamination failure in a single package. The methodology was demonstrated through a local three-dimensional pull-off failure analysis and a geometrically nonlinear structural analysis of a five-foot composite helicopter fuselage section. Pull-off specimens were used to identify potential debonding failure of co-cured skin-stringer/frame fuselage structures. An investigation of the failed pull-off specimens was performed to determine the location of the failure initiation. Three-dimensional strain energy release rate analysis indicates that the delamination initiation and growth is controlled by Mode 1 opening mode. The bending moment at the delamination tip was identified as the crucial factor controlling the failure. The geometrically nonlinear structural analysis of a five-foot composite fuselage section was performed using a detailed finite element model. Loads were applied along the periphery of the subcomponent using displacement fields generated from solutions of a full-vehicle model.

  20. 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

  1. Analysis of multistate models for electromigration failure

    NASA Astrophysics Data System (ADS)

    Dwyer, V. M.

    2010-02-01

    The application of a multistate Markov chain is considered as a model of electromigration interconnect degradation and eventual failure. Such a model has already been used [Tan et al., J. Appl. Phys. 102, 103703 (2007)], maintaining that, in general, it leads to a failure distribution described by a gamma mixture, and that as a result, this type of distribution (rather than a lognormal) should be used as a prior in any Bayesian mode fitting and subsequent reliability budgeting. Although it appears that the model is able to produce reasonably realistic resistance curves R(t), we are unable to find any evidence that the failure distribution is a simple gamma mixture except under contrived conditions. The distributions generated are largely sums of exponentials (phase-type distributions), convolutions of gamma distributions with different scales, or roughly normal. We note also some inconsistencies in the derivation of the gamma mixture in the work cited above and conclude that, as it stands, the Markov chain model is probably unsuitable for electromigration modeling and a change from lognormal to gamma mixture distribution generally cannot be justified in this way. A hidden Markov model, which describes the interconnect behavior at time t rather than its resistance, in terms of generally observed physical processes such as void nucleating, slitlike growth (where the growth is slow and steady), transverse growth, current shunting (where the resistance jumps in value), etc., seems a more likely prospect, but treating failure in such a manner would still require significant justification.

  2. Analysis of field data on computer failures

    NASA Technical Reports Server (NTRS)

    Iyer, Ravishankar K.; Hsueh, Mei-Chen

    1990-01-01

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

  3. 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.

  4. Failure analysis of ceramic-to-metal seals

    SciTech Connect

    Gates, W.G.

    1980-03-01

    Ceramic-to-metal seal failures that occur at the next assembly level present a critical problem because of the time and expense involved in the assembly of electro-mechanical switches. A typical analysis of a failed assembly and a recommended rework process is presented. In addition, steps are proposed to minimize the occurrence of future ceramic-to-metal seal failures.

  5. 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.

  6. Backside preparation and failure analysis for packaged microelectromechanical systems (MEMS)

    NASA Astrophysics Data System (ADS)

    Walraven, Jeremy A.; Cole, Edward I., Jr.; Barr, David L.; Anderson, Richard E.; Kilgo, Alice; Maciel, John J.; Morrison, Richard; Karabudak, Nafiz N.

    2004-12-01

    Failure analysis tools and techniques that identify root cause failure mechanisms are key components to improving MEMS technology. Failure analysis and characterization are relatively simple at the wafer and die level where chip access is straightforward. However, analysis and characterization of packaged parts or components encapsulated with covers, caps, etc may be more cumbersome and lead to problems assessing the root cause of failure. This paper will discuss two methods used to prepare the backside of the package/device to allow for failure analysis and inspection of different MEMS components without removing the cap, cover, or lid on the device and/or the package. One method for backside preparation was grinding and polishing the package for IR inspection. This method involved backfilling the package cavity with epoxy to hold the die in place. The other method involved opening a window through the backside of the package, exposing the die for IR inspection. Failure analysis results showed both methods of backside preparation were successful in revealing the failure mechanisms on two different MEMS technologies.

  7. Backside preparation and failure analysis for packaged microelectromechanical systems (MEMS)

    NASA Astrophysics Data System (ADS)

    Walraven, Jeremy A.; Cole, Edward I., Jr.; Barr, David L.; Anderson, Richard E.; Kilgo, Alice; Maciel, John J.; Morrison, Richard; Karabudak, Nafiz N.

    2005-01-01

    Failure analysis tools and techniques that identify root cause failure mechanisms are key components to improving MEMS technology. Failure analysis and characterization are relatively simple at the wafer and die level where chip access is straightforward. However, analysis and characterization of packaged parts or components encapsulated with covers, caps, etc may be more cumbersome and lead to problems assessing the root cause of failure. This paper will discuss two methods used to prepare the backside of the package/device to allow for failure analysis and inspection of different MEMS components without removing the cap, cover, or lid on the device and/or the package. One method for backside preparation was grinding and polishing the package for IR inspection. This method involved backfilling the package cavity with epoxy to hold the die in place. The other method involved opening a window through the backside of the package, exposing the die for IR inspection. Failure analysis results showed both methods of backside preparation were successful in revealing the failure mechanisms on two different MEMS technologies.

  8. Fast failure analysis and yield enhancement: an integrated approach

    NASA Astrophysics Data System (ADS)

    Lee, Fourmun; Doan, Nam; Liu, Lisa H.

    1996-09-01

    This paper describes the integrated fast failure analysis/yield enhancement system used at Motorola's MOS-12 fab, established with the goal of providing high speed diagnostics and feedback. This goal was achieved through tight integration of in-fab inspection tools with electrical test equipment, out-of-fab analytical tools, and software tools. At this facility, the use of common file formats permits data exchange between wafer inspection tools, optical review stations, SEM, FIB, and electrical work bench testers. Wafer images generated at all diagnostic tools are stored on a video archival/retrieval system (VARSTM). Correlation is a powerful tool for reducing failure analysis time and increasing failure analysis efficiency. By overlaying in-line inspection data with process, parametric, sort bin, and bitmap data, the locations of potential killer defects are rapidly identified. Physical failure analysis is performed on selected correlated failures to confirm the cause of device failures. Using analytical instruments with full wafer capability, in-line inspection or bitmap information are used to quickly locate the defects of interest. This approach has been successfully used to significantly reduce FA time compared with traditional FA methods. Fast failure analysis/yield enhancement is demonstrated with three case studies.

  9. 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.

  10. 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.

  11. 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…

  12. 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.

  13. 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

  14. 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.

  15. 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.}

  16. 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.

  17. 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.

  18. 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.

  19. Development of partial failure analysis method in probability risk assessments

    SciTech Connect

    Ni, T.; Modarres, M.

    1996-12-01

    This paper presents a new approach to evaluate the partial failure effect on current Probability Risk Assessments (PRAs). An integrated methodology of the thermal-hydraulic analysis and fuzzy logic simulation using the Dynamic Master Logic Diagram (DMLD) was developed. The thermal-hydraulic analysis used in this approach is to identify partial operation effect of any PRA system function in a plant model. The DMLD is used to simulate the system performance of the partial failure effect and inspect all minimal cut sets of system functions. This methodology can be applied in the context of a full scope PRA to reduce core damage frequency. An example of this application of the approach is presented. The partial failure data used in the example is from a survey study of partial failure effects from the Nuclear Plant Reliability Data System (NPRDS).

  20. 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.

  1. 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.

  2. 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.

  3. [Failure analysis of medical linear accelerator with reliability analyses].

    PubMed

    Zakimi, Ken; Watanabe, Hiroyuki; Ishida, Hideki; Take, Toshio; Kato, Mitsuyoshi; Iwai, Tsugunori; Nitta, Masaru; Kato, Kyouichi; Nakazawa, Yasuo

    2014-12-01

    We analyzed a number of cases about the Linac troubles in our hospital and have examined the effect of preventive maintenance with Weibull analysis and exponential distribution from April 2001 to March 2012. The total failure by irradiation disabled was 1, 192. (1) Medical linear accelerator (MLC) system was 24.0%, (2) radiation dosimetry system 13.1%, and the (3) cooling-water system was 26.5%. It accounts for 63.6% of the total number of failures. Each parameter value m, which means the shape parameter, and the failure period expectancy of parts μ were (1) 1.21, 1.46/3.9, 3.8 years. 3.7, 3.6 years. (2) 2.84, 1.59/6.6, 4.3 years. 6.7, 5.9 years. (3) 5.12, 4.16/6.1, 8.5 years. 6.1, 8.5 years. Each shape parameter was m>1. It is believed that they are in the worn-out failure period. To prevent failure, MLC performance should be overhauled once every 3 years and a cooling unit should be overhauled once every 7 years. Preventive maintenance is useful in assessing the failure of radiation therapy equipment. In a radiation dosimetry part, you can make a preemptive move before the failure by changing the monitor's dosimeter board with a new part from the repairs stockpiled every 6 months for maintenance.

  4. An Analysis of the Secondary School Clerical Aide Occupation.

    ERIC Educational Resources Information Center

    Murphy, Judy K.; And Others

    The general purpose of the occupational analysis is to provide workable, basic information dealing with the many and varied duties performed in the secondary school clerical aide occupation. The document opens with a brief introduction followed by a job description. The bulk of the document is presented in table form. Seven duties are broken down…

  5. Issues of Aid to Nonpublic Schools. Summary Analysis.

    ERIC Educational Resources Information Center

    Erickson, Donald A.; Madaus, George F.

    This is a summary analysis of Volumes I, II, III, and IV (see ED 058 486--489 of Issues of Aid to Nonpublic Schools. The cardinal ideas in these volumes are discussed under the following topics: Popular Fallacies as to the Role of Nonpublic Schools; The Nature of the Crisis in Nonpublic Schools; and Perils of Public Policy. The central outcomes of…

  6. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., 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 flight... probability estimate must use accurate data, scientific principles, and a method that is statistically...

  7. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ..., 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 flight... probability estimate must use accurate data, scientific principles, and a method that is statistically...

  8. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ..., 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 flight... probability estimate must use accurate data, scientific principles, and a method that is statistically...

  9. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., 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 flight... probability estimate must use accurate data, scientific principles, and a method that is statistically...

  10. 14 CFR 417.224 - Probability of failure analysis.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ..., 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 flight... probability estimate must use accurate data, scientific principles, and a method that is statistically...

  11. 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.

  12. 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.

  13. Failure analysis and modeling of a VAXcluster system

    NASA Technical Reports Server (NTRS)

    Tang, Dong; Iyer, Ravishankar K.; Subramani, Sujatha S.

    1990-01-01

    This paper discusses the results of a measurement-based analysis of real error data collected from a DEC VAXcluster multicomputer system. In addition to evaluating basic system dependability characteristics such as error and failure distributions and hazard rates for both individual machines and for the VAXcluster, reward models were developed to analyze the impact of failures on the system as a whole. The results show that more than 46 percent of all failures were due to errors in shared resources. This is despite the fact that these errors have a recovery probability greater than 0.99. The hazard rate calculations show that not only errors, but also failures occur in bursts. Approximately 40 percent of all failures occur in bursts and involved multiple machines. This result indicates that correlated failures are significant. Analysis of rewards shows that software errors have the lowest reward (0.05 vs 0.74 for disk errors). The expected reward rate (reliability measure) of the VAXcluster drops to 0.5 in 18 hours for the 7-out-of-7 model and in 80 days for the 3-out-of-7 model.

  14. 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.

  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. Computer-aided petrographic analysis of sandstones

    SciTech Connect

    Thayer, P.A.; Helmold, K.P.

    1987-05-01

    Thin-section point counting, mathematical and statistical analysis of petrographic-petrophysical data, report generation, and graphical presentation of results can be done efficiently by computer. Compositional and textural data are collected with a modified Schares point-counting system. The system uses an MS-DOS microcomputer programmed in BASIC to drive a motorized stage attached to a polarizing microscope. Numeric codes for up to 500 different categories of minerals, cements, pores, etc, are input using a separate keypad. Calculation and printing of constituent percentages, QFR, Folk name, and grain-size distribution are completed in seconds after data entry. Raw data files, compatible with software such as Lotus 1-2-3, SPSS, and SAS, are stored on floppy disk. Petrographic data files are transferred directly to a mainframe, merged with log and petrophysical data, analyzed statistically with SAS, and reports generated. SAS/GRAPH and TELL-A-GRAF routines linked with SAS generate a variety of cross plots, histograms, pie and bar charts, ternary diagrams, and vertical variation diagrams (e.g., depth vs. porosity, permeability, mean size, sorting, and percent grains-matrix-cement).

  17. 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.

  18. 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.

  19. 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…

  20. 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.

  1. 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.

  2. SOLERAS - Analysis of photovoltaic concentrator module failures and repair methods

    SciTech Connect

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

    1987-06-01

    This report presents the results of the failure analysis, performed from early 1984 through September 1986 on the open-circuited modules, and the assessment of repairing these modules on site at the Solar Village. 16 refs., 26 figs., 19 tabs.

  3. Analysis of Defects and Failures A Materials Course for Engineers.

    ERIC Educational Resources Information Center

    Bourgault, R. F.

    Today, product liability cases seem to be increasing rapidly in both number and extent of liability of the manufacturer. Where analysis of defects and failures was once of interest to the enlightened company, it could well become a necessity for survival of all in the future. The materials engineer is likely to find many opportunities for…

  4. 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…

  5. 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.

  6. HIV/AIDS in Cuba: a rights-based analysis.

    PubMed

    Anderson, Tim

    2009-01-01

    The common assertion that Cuba's achievements in HIV/AIDS control have come at a cost in human rights is reinforced by US hostility toward its small neighbor. Nevertheless, a rights-based analysis may be one useful way of examining the actual Cuban experience. By reference to the United Nation's Guidelines on HIV/AIDS and Human Rights, this paper examines the Cuban experience as it relates to the themes of quarantine and personal freedom; privacy in testing and tracing; education, participation, and non-discrimination; and the availability of AIDS treatment. The paper concludes that Cuba's quarantine period was unnecessarily prolonged in the late 1980s but that this prolonged quarantine did not target men who have sex with men. Testing and tracing procedures in Cuba follow a standard protocol, but they are more thorough than elsewhere. Cuba has strengthened participation in education programs, and treatment is now the best in the Caribbean region. The human rights implications of HIV programs must be considered in an integrated way. Selective criticisms of the Cuban program have not improved international understanding of HIV/AIDS treatment in Cuba.

  7. 3D statistical failure analysis of monolithic dental ceramic crowns.

    PubMed

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

    2016-07-01

    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. PMID:27215334

  8. 3D statistical failure analysis of monolithic dental ceramic crowns.

    PubMed

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

    2016-07-01

    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.

  9. 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

  10. The opportunities for the Internet to assist with failure analysis

    SciTech Connect

    Graham-Jones, P.J.; Mellor, B.G.

    1997-12-01

    One of the major reasons for the failure of components is the lack of information readily available to engineers. An engineer cannot be expected to known everything and thus must rely on information that is both accurate and relevant. Within the paper the opportunities for the Internet to assist the engineer by supplying accurate and relevant information are investigated. It is foreseen that rapid development in this field will produce many opportunities for companies to exploit, but a careful evaluation of the requirements and a commonality in the structure and computer protocols used is paramount to the success of such developments. Two techniques are extensively discussed: data mining and the World Wide Web (WWW). Data mining can show the relative occurrence of failure modes and this can help develop Expert and knowledge based systems. Using the WWW, a knowledge-based system for failure analysis has been developed.

  11. 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.

  12. 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.

  13. 77 FR 1491 - Sigma Corporation; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-10

    ... Sigma Corporation; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... of thirty (30) days. The following Analysis to Aid Public Comment describes the terms of the...

  14. 75 FR 46940 - Nufarm Limited; Analysis of Agreement Containing Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-04

    ... Nufarm Limited; Analysis of Agreement Containing Consent Order to Aid Public Comment AGENCY: Federal... methods of competition. The attached Analysis to Aid Public Comment describes both the allegations in the... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

  15. 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

    ... 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 the... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

  16. 76 FR 15311 - Legacy Learning Systems, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-21

    ... Legacy Learning Systems, 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 the... period of thirty (30) days. The following Analysis to Aid Public Comment describes the terms of...

  17. 75 FR 70921 - Simon Property Group, Inc.; Analysis of Proposed Agreement Containing Consent Orders To Aid...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-19

    ... Simon Property Group, Inc.; Analysis of Proposed Agreement Containing Consent Orders To Aid Public... practices or unfair methods of competition. The attached Analysis to Aid Public Comment describes both the... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

  18. 78 FR 55076 - Ganley Ford West, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-09-09

    ... Ganley Ford West, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... placed on the public record for a period of thirty (30) days. The following Analysis to Aid...

  19. 75 FR 37806 - Twitter, Inc.; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-30

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  20. 77 FR 33218 - Graco, Inc.; Analysis of Proposed Agreement Containing Consent Orders To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-06-05

    ... Graco, Inc.; Analysis of Proposed Agreement Containing Consent Orders To Aid Public Comment AGENCY... unfair methods of competition. The attached Analysis to Aid Public Comment describes both the allegations... public record for a period of thirty (30) days. The following Analysis to Aid Public Comment...

  1. 77 FR 12590 - Winchester Industries; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... Winchester Industries; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... public record for a period of thirty (30) days. The following Analysis to Aid Public Comment...

  2. 77 FR 12584 - Gorell Enterprises, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... Gorell Enterprises, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the ] draft complaint... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

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

    NASA Astrophysics Data System (ADS)

    Naidu, Sanjiv H.

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

  4. Kinematics Analysis of an Aided Robot for Needle Insertion

    NASA Astrophysics Data System (ADS)

    Li, Qiang; Gao, Dedong; Wang, Shan; Bai, Huiquan; Zheng, Haojun

    The kinematic relationship between the needle base and the robot's joints is analyzed. The analysis process is based on the aided needle-insertion robot built by our group. The thinking of needle-inserting procedure is confirming the needle base's posture before the needle inserted into tissue. The method of Denavit-Hartenberg (D-H) parameters is used to establish a link robot body-frames with the structural characteristics of the robot. After analysing kinematics, the kinematics equation is presented. The kinematics inverse solutions are obtained with the analytical method and geometry analysis method.

  5. A review of the technology and process on integrated circuits failure analysis applied in communications products

    NASA Astrophysics Data System (ADS)

    Ming, Zhimao; Ling, Xiaodong; Bai, Xiaoshu; Zong, Bo

    2016-02-01

    The failure analysis of integrated circuits plays a very important role in the improvement of the reliability in communications products. This paper intends to mainly introduce the failure analysis technology and process of integrated circuits applied in the communication products. There are many technologies for failure analysis, include optical microscopic analysis, infrared microscopic analysis, acoustic microscopy analysis, liquid crystal hot spot detection technology, optical microscopic analysis technology, micro analysis technology, electrical measurement, microprobe technology, chemical etching technology and ion etching technology. The integrated circuit failure analysis depends on the accurate confirmation and analysis of chip failure mode, the search of the root failure cause, the summary of failure mechanism and the implement of the improvement measures. Through the failure analysis, the reliability of integrated circuit and rate of good products can improve.

  6. Hydromechanical Failure Analysis Associated with Laurentide Ice Sheet Glaciations

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Person, M. A.; Voller, V. R.

    2015-12-01

    Glacial loading by continental ice sheets has been linked to large (> M6) Late Pleistocene and Holocene seismicity in Scandinavia and North America along with sedimentary basin blowout features such as Lake Howe, Manitoba Canada and glacio-tectonic thrust structures. The specter of future glaciations is considered one of the most important factors to consider in siting of high-level nuclear wastes in Switzerland, Canada, and Sweden. To date, continental-scale analysis of crustal failure has focused on mechanical failure which has neglected the effects of pore pressure and permeability changes. We have developed a two-dimensional, Cartesian, elastic, plane strain control volume finite element (CVFEM) model to investigate the effect of pore pressure on the failure potential along a cross-sectional transect stretching from the Hudson Bay to the Gulf of Mexico. Our analysis considers fluid flow and pore pressure eveolution within the upper 10km of the earths crust and mechanical deformation within at 100 km thick lithosphere. We imposed 4 cycles of glaciation of the Laurentide ice sheet during the Last Late Pleistocene. The geomechanical deformation is coupled to the fluid flow through time dependent changes in the mean normal stress. We have conducted a sensitivity study in which we have varied the permeability of the upper crust between a range of 10-20 to 10-14 m2. We solve a series of one-dimensional heat transfer equations to determine regions where the Laurentide ice sheet is wet based or frozen. A Mohr-Coulomb failure criteria was used to analyze the potential of seismicity and permeability changes along pre-existing critically stressed faults. Mechanically failure (neglecting pore pressure evolution, see Figure A attached) caused by ice sheet induced stress perturbation were found to be primarily concentrate in the forebulge region of the ice sheet with the effective Coulomb stress being 4.4 MPa. However, when pore pressure evolution is considered in the

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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

  12. 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.

  13. 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.

  14. 77 FR 65550 - Compete, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-29

    ... Compete, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade Commission.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... Aid Public Comment describes the terms of the consent agreement, and the allegations in the...

  15. 77 FR 2724 - CVS Caremark Corporation; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-01-19

    ... Caremark Corporation; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... Aid Public Comment describes the terms of the consent agreement, and the allegations in the...

  16. HIV/AIDS information by African companies: an empirical analysis.

    PubMed

    Barako, Dulacha G; Taplin, Ross H; Brown, Alistair M

    2010-01-01

    This article investigates the extent of Human Immunodeficiency Virus/Acquired Immune Deficiency Syndrome Disclosures (HIV/AIDSD) in online annual reports by 200 listed companies from 10 African countries for the year ending 2006. Descriptive statistics reveal a very low level of overall HIV/AIDSD practices with a mean of 6 per cent disclosure, with half (100 out of 200) of the African companies making no disclosures at all. Logistic regression analysis reveals that company size and country are highly significant predictors of any disclosure of HIV/AIDS in annual reports. Profitability is also statistically significantly associated with the extent of disclosure.

  17. Computer-aided analysis of optical data link (Poster Paper)

    NASA Astrophysics Data System (ADS)

    Lin, Jizoo; Wang, Yuh-Diahn; Shih, Ming-Tang

    1992-10-01

    This paper presents a fiber optic simulation methodology for the design of digital lightwave link. Computer-aided analysis of high speed optical data link is important for a system designer to predict the system performance in advanced. Accurate modeling and simulation contribute the fundamental evaluation of optical communication integrated circuit feasibilities. In this paper, the modeling of optical source waveform, transmission fiber, photodetector and timing recovery technique using surface acoustic wave (SAW) filter are discussed. A SONET OC-3 transceiver is simulated as an example, while measured eye diagrams are compared with the simulation result.

  18. 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.

  19. 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…

  20. 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.

  1. Prediction of hospital failure: a post-PPS analysis.

    PubMed

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

    1996-01-01

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

  2. 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.

  3. Failure analysis of electrolyte-supported solid oxide fuel cells

    NASA Astrophysics Data System (ADS)

    Fleischhauer, Felix; Tiefenauer, Andreas; Graule, Thomas; Danzer, Robert; Mai, Andreas; Kuebler, Jakob

    2014-07-01

    For solid oxide fuel cells (SOFCs) one key aspect is the structural integrity of the cell and hence its thermo mechanical long term behaviour. The present study investigates the failure mechanisms and the actual causes for fracture of electrolyte supported SOFCs which were run using the current μ-CHP system of Hexis AG, Winterthur - Switzerland under lab conditions or at customer sites for up to 40,000 h. In a first step several operated stacks were demounted for post-mortem inspection, followed by a fractographic evaluation of the failed cells. The respective findings are then set into a larger picture including an analysis of the present stresses acting on the cell like thermal and residual stresses and the measurements regarding the temperature dependent electrolyte strength. For all investigated stacks, the mechanical failure of individual cells can be attributed to locally acting bending loads, which rise due to an inhomogeneous and uneven contact between the metallic interconnect and the cell.

  4. Electrical power requirements analysis. Single failure tolerant entry

    NASA Technical Reports Server (NTRS)

    Pipher, M. D.; Green, P. A.; Wolfgram, D. F.

    1977-01-01

    The results of an analysis of the orbiter electrical power system for the case of a single failure tolerant (SFT) entry are presented. The analysis was performed using the shuttle electrical power system analysis computer program. It was performed to permit assessment of the capability of the orbiter systems to support the proposed entry configuration and to provide the data necessary to identify potential constraints and limitations. Three contingency modes have been identified which would require an SFT entry. This analysis addresses an SFT entry resulting from the loss of two fuel cell powerplants, while on orbit. The results of the analysis indicate that, even under near optimum conditions, the fuel cell power demand will exceed the tested operating capacity of 16 kw, and that various electrical components may experience voltages below 24 VDC.

  5. A multiple imputation approach to the analysis of interval-censored failure time data with the additive hazards model

    PubMed Central

    Chen, Ling; Sun, Jianguo

    2013-01-01

    This paper discusses regression analysis of interval-censored failure time data, which occur in many fields including demographical, epidemiological, financial, medical, and sociological studies. For the problem, we focus on the situation where the survival time of interest can be described by the additive hazards model and a multiple imputation approach is presented for inference. A major advantage of the approach is its simplicity and it can be easily implemented by using the existing software packages for right-censored failure time data. Extensive simulation studies are conducted which indicate that the approach performs well for practical situations and is comparable to the existing methods. The methodology is applied to a set of interval-censored failure time data arising from an AIDS clinical trial. PMID:25419022

  6. 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

  7. Computer-aided strength analysis of the modernized freight wagon

    NASA Astrophysics Data System (ADS)

    Płaczek, M.; Wróbel, A.; Baier, A.

    2015-11-01

    In the paper results of computer-aided strength analysis of the modernized freight wagon based on Finite Element Method are presented. CAD model of the considered freight wagon was created and its strength was analysed in agreement with norms described the way of such kind of freight wagons testing. Then, the model of the analysed freight wagon was modernized by adding composite panels covering the inner surface of the vehicle body. Strength analysis was carried out once again and obtained results were juxtaposed. This work was carried out in order to verify the influence of composite panels on the strength of the freight car body and to estimate the possibility of reducing the steel shell thickness of the box in order to reduce weight of the freight wagon.

  8. 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.

  9. State Aid and Student Performance: A Supply-Demand Analysis

    ERIC Educational Resources Information Center

    Kinnucan, Henry W.; Zheng, Yuqing; Brehmer, Gerald

    2006-01-01

    Using a supply-demand framework, a six-equation model is specified to generate hypotheses about the relationship between state aid and student performance. Theory predicts that an increase in state or federal aid provides an incentive to decrease local funding, but that the disincentive associated with increased state aid is moderated when federal…

  10. 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.

  11. 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.

  12. Software for computer-aided receiver operating characteristic (ROC) analysis

    NASA Astrophysics Data System (ADS)

    Engel, John R.; Craine, Eric R.

    1994-04-01

    We are currently developing an easy-to-use, microcomputer-based software application to help researchers perform ROC studies. The software will have facilities for aiding the researcher in all phases of an ROC study, including experiment design, setting up and conducting test sessions, analyzing results and generating reports. The initial version of the software, named 'ROC Assistant', operates on Macintosh computers and enables the user to enter a case list, run test sessions and produce an ROC curve. We are in the process of developing enhanced versions which will incorporate functions for statistical analysis, experimental design and online help. In this paper we discuss the ROC methodology upon which the software is based as well as our software development effort to date.

  13. Improved reliability analysis method based on the failure assessment diagram

    NASA Astrophysics Data System (ADS)

    Zhou, Yu; Zhang, Zheng; Zhong, Qunpeng

    2012-07-01

    With the uncertainties related to operating conditions, in-service non-destructive testing (NDT) measurements and material properties considered in the structural integrity assessment, probabilistic analysis based on the failure assessment diagram (FAD) approach has recently become an important concern. However, the point density revealing the probabilistic distribution characteristics of the assessment points is usually ignored. To obtain more detailed and direct knowledge from the reliability analysis, an improved probabilistic fracture mechanics (PFM) assessment method is proposed. By integrating 2D kernel density estimation (KDE) technology into the traditional probabilistic assessment, the probabilistic density of the randomly distributed assessment points is visualized in the assessment diagram. Moreover, a modified interval sensitivity analysis is implemented and compared with probabilistic sensitivity analysis. The improved reliability analysis method is applied to the assessment of a high pressure pipe containing an axial internal semi-elliptical surface crack. The results indicate that these two methods can give consistent sensitivities of input parameters, but the interval sensitivity analysis is computationally more efficient. Meanwhile, the point density distribution and its contour are plotted in the FAD, thereby better revealing the characteristics of PFM assessment. This study provides a powerful tool for the reliability analysis of critical structures.

  14. 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. PMID:23294402

  15. 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.

  16. 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

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  19. Failure mechanics of fiber composite notched charpy specimens. [stress analysis

    NASA Technical Reports Server (NTRS)

    Chamis, C. C.

    1976-01-01

    A finite element stress analysis was performed to determine the stress variation in the vicinity of the notch and far field of fiber composites Charpy specimens (ASTM Standard). NASTRAN was used for the finite element analysis assuming linear behavior and equivalent static load. The unidirectional composites investigated ranged from Thornel 75 Epoxy to S-Glass/Epoxy with the fiber direction parallel to the long dimension of the specimen. The results indicate a biaxial stress state exists in (1) the notch vicinity which is dominated by transverse tensile and interlaminar shear and (2) near the load application point which is dominated by transverse compression and interlaminar shear. The results also lead to the postulation of hypotheses for the predominant failure modes, the fracture initiation, and the fracture process. Finally, the results indicate that the notched Charpy test specimen is not suitable for assessing the impact resistance of nonmetallic fiber composites directly.

  20. Controllability Analysis for Multirotor Helicopter Rotor Degradation and Failure

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

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

  1. 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.

  2. 77 FR 12591 - THV Holdings LLC; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... Holdings LLC; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade Commission.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... Commission, has been placed on the public record for a period of thirty (30) days. The following Analysis...

  3. 77 FR 12588 - Long Fence & Home, LLLP; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... Long Fence & Home, LLLP; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint and... Commission, has been placed on the public record for a period of thirty (30) days. The following Analysis...

  4. 77 FR 12586 - Serious Energy, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-03-01

    ... Serious Energy, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis To Aid Public Comment describes both the allegations in the draft complaint and... Commission, has been placed on the public record for a period of thirty (30) days. The following Analysis...

  5. 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.

  6. Incorporating Classification Uncertainty in Competing- risks Nest- failure Analysis

    EPA Science Inventory

    Nesting birds risk nest failure due to many causes. Though partitioning risk of failure among causes has long been of interest to ornithologists, formal methods for estimating competing risk have been lacking.

  7. Failure analysis report geothermal steam muffler diffusers, the Geysers, California

    SciTech Connect

    McAlpin, Ron; Ellis, Peter F.

    1980-04-01

    On 29 January 1980, the Failure Analysis Laboratory at Radian Corporation received portions of the inner and outer diffusers from a geothermal steam discharge silencer-operated by Thermogenics, Incorporated at Unit No.15, The Geysers, California, for determination of the cause of premature failure, This and several other T 304 stainless steel diffusers have failed with numerous cracks evident. This report considers the causes of failure of the inner and outer diffusers. A geothermal discharge silencer with steam input line is shown in Figure 1; Figure 2 shows several failed stainless steel diffusers. This report is part of a continuing DOE effort to gain insight into component materials employed in geothermal energy utilization. The results of these analyses will be incorporated into the next issue of DOE's Material Selection Guidelines for Geothermal Energy Systems. The first commercial production of electricity from geothermal energy in the western hemisphere occurred in 1960 at The Geysers, a vapor-dominated resource located in Sonoma and Lake counties, California. Steam from numerous geothermal wells is supplied to fifteen generating units with a combined capacity of over 900 Mw(e). When a turbine is tripped off-line, steam is discharged through a silencer for noise abatement, as required by environmental regulations. The silencer at Unit 15 consists of two double-walled cylindrical diffusers mounted horizontally in the base of a discharge tower (Figure 1). During a trip, approximately 550,000 lb{sub m}/hr of steam at 350 F is vented through the silencer. The duration of a trip cycle varies from several hours to a full week. Unit No.15 is the only unit at The Geysers to use a stainless steel diffuser type muffler. All other units have successfully operated with a carbon steel distribution header imbedded in a redwood box filled with lava rock. In the stack shown in Figure 1, there are two sets of diffusers, each with an inner and outer diffuser; both have

  8. 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,

  9. Code System for the Analysis of Component Failure Data with a Compound Statistical Model.

    2000-08-22

    Version 00 Two separate but similar Fortran computer codes have been developed for the analysis of component failure data with a compound statistical model: SAFE-D and SAFE-R. The SAFE-D code (Statistical Analysis for Failure Estimation-failure-on-Demand) analyzes data which give the observed number of failures (failure to respond properly) in a specified number of demands for several similar components that should change their condition upon demand. The second program, SAFE-R (Statistical Analysis for Failure Estimation-failure Rate)more » is to be used to analyze normally operating components for which the observed number of failures in a specified operating time is given. In both these codes the failure parameter (failure probability per demand for SAFE-D or failure rate for SAFE-R) may be assumed equal for all similar components (the homogeneous failure model) or may be assumed to be a random variable distributed among similar components according to a prior distribution (the heterogeneous or compound failure model). Related information can be found at the developer's web site: http://www.mne.ksu.edu/~jks/.« less

  10. 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.

  11. 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.

  12. 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…

  13. 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…

  14. Who Gets More Financial Aid in China? A Multilevel Analysis

    ERIC Educational Resources Information Center

    Yang, Po

    2010-01-01

    The Chinese financial aid system intends to increase the affordability of postsecondary education and provide access to college for disadvantaged students. However, the research base for access to aid in China is extremely thin. Using data from a large cross-sectional survey in Beijing, this study found that attending selective institutions with…

  15. 78 FR 46952 - Relief-Mart, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-02

    ... Marketing Claims, 77 FR 62, 122, 62,123 (Oct. 11, 2012). Parts III though VI require Relief-Mart to: Keep... Relief-Mart, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade.... The attached Analysis to Aid Public Comment describes both the allegations in the draft complaint...

  16. 48 CFR 915.404-2-70 - Audit as an aid in proposal analysis.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 5 2010-10-01 2010-10-01 false Audit as an aid in proposal analysis. 915.404-2-70 Section 915.404-2-70 Federal Acquisition Regulations System DEPARTMENT OF... Audit as an aid in proposal analysis. (a) When a contract price will be based on cost or pricing...

  17. 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.

  18. 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.

  19. 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.

  20. Computer-aided analysis of a Superfund site

    SciTech Connect

    Qualheim, B.J. )

    1990-05-01

    The groundwater investigation at the Lawrence Livermore National Laboratory was initiated in 1983 after perchloroethylene (PCE) and trichloroethylene (TCE) were detected in the groundwater. Since that time, more than 300 monitor wells have been completed, logged, sampled, and hydraulically tested. In 1987, the Livermore site was placed on the Environmental Protection Agency's National Priority List (Superfund). The Livermore valley is relatively flat, underlain by a complex alluvial sedimentary basin drained by two intermittent streams. The subsurface consists of unconsolidated sand, gravel, silt, and clay with multiple water-bearing zones of relatively high permeability. The hydrogeologic system is characterized as leaky, with horizontal hydraulic communication of up to 800 ft and vertical communication between aquifers of up to 50 ft. Computer-based analysis of the site stratigraphy was used to analyze and characterize the subsurface. The authors used a computer-aided design and drafting (CADD) system to create two-dimensional slices of the subsurface. The slice program takes a subsurface slice at any specified depositional gradient and at any slice thickness. A slice displays the lithology type, unit thickness, depth of slice, and chemical analyses for volatile organic compounds (VOCs). The lateral continuity of subsurface channels was mapped for each depth slice. By stacking these maps, the authors interpreted a pseudo-three-dimensional representation of probably pathways for VOC movement in the subsurface. An enhanced computer graphics system was also used to map the movement of VOCs in the subsurface.

  1. 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.

  2. 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

  3. 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

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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

  9. 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.

  10. Probabilistic failure analysis of a water-cooled tungsten divertor: Impact of embrittlement

    NASA Astrophysics Data System (ADS)

    You, J.-H.; Komarova, I.

    2008-04-01

    Inherent brittleness and neutron embrittlement are critical weaknesses of tungsten for fusion application. Pronounced scattering of the fracture strength of tungsten requires a statistical treatment. Thus, the risk of structural failure of a tungsten component can be estimated only in a probabilistic framework. In this work, we applied a probabilistic failure analysis code STAU to estimate the failure risk of a water-cooled tungsten mono-block divertor component. The STAU code was based on the weakest-link failure theory and linear elastic fracture mechanics. A typical heat flux load being expected for a fusion reactor was considered for the FEM stress analysis. The failure probability was computed considering various mixed-mode fracture criteria. Both the experimentally estimated and hypothetical Weibull parameters were used as material data. In the case of unirradiated tungsten, the failure probability was acceptably small whereas reduced Weibull parameters led to significantly increased failure risk.

  11. 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.

  12. 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.

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

    PubMed

    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

  14. 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.

  15. 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…

  16. An AID analysis of factors associated with contemporary net migration in the United States.

    PubMed

    Roseman, C C; Ives, S M; Shelley, F M

    1980-01-01

    The authors use Automatic Interaction Detector (AID) analysis to examine variables associated with net U.S. migration by county for the period 1970-1975. "The AID analyses also reveal various ways in which several factors combine to characterize places of substantial growth or decline through migration." Government employment is identified as a major factor associated with net positive migration

  17. 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

  18. 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.

  19. 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.

  20. 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.

  1. Failure analysis of a tool steel torque shaft

    NASA Technical Reports Server (NTRS)

    Reagan, J. R.

    1983-01-01

    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. Previously announced in STAR as N82-11184

  2. 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.

  3. Failures during construction of a landfill lining: a case analysis.

    PubMed

    Blight, Geoffrey E

    2007-08-01

    Two tension failures occurred during the construction of the protection and leachate drainage layers for a geomembrane landfill liner on a slope of 24 degrees to the horizontal. The paper describes and analyses the design and shows that the failures occurred largely because the sequence of construction was altered without due consideration of the consequences. The designers also appeared unaware that there is a difference between the nominal strength of a structural element and its actual in-service strength. This misconception also played a major part in the failures. PMID:17874659

  4. 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

  5. Constructing an effective prevention mechanism for MSW lifecycle using failure mode and effects analysis.

    PubMed

    Chen, Ying-Chu; Wu, Wen-Fang

    2015-12-01

    Municipal solid waste in Taiwan is a valuable source of renewable energy. Phases of municipal solid waste lifecycle (classification, disposal, storage, collection and transportation) before incineration or landfilled face various potential failures. Applying a proper technique to eliminate or decrease potential failures is desirable and needed. Failure Modes and Effects Analysis to municipal solid waste lifecycle was found in literature. This study utilized the Failure Modes and Effects Analysis as a convenient technique for determining, classifying and analyzing common failures in the municipal solid waste lifecycle. As a result, an appropriate risk scoring of severity, occurrence, and detection of failure modes and computing the Risk Priority Number for identifying the high potential failure modes were made. Nineteen failure modes were identified, and nine of them were ranked as the priority items for improvement. Recommended actions for all failure modes were suggested. Occurrences of failures were remarkably reduced after implementing the procedure for six months. The results of this study have minimized potential failures and brought continuous improvement, thus achieving a better protection of the environment.

  6. Constructing an effective prevention mechanism for MSW lifecycle using failure mode and effects analysis.

    PubMed

    Chen, Ying-Chu; Wu, Wen-Fang

    2015-12-01

    Municipal solid waste in Taiwan is a valuable source of renewable energy. Phases of municipal solid waste lifecycle (classification, disposal, storage, collection and transportation) before incineration or landfilled face various potential failures. Applying a proper technique to eliminate or decrease potential failures is desirable and needed. Failure Modes and Effects Analysis to municipal solid waste lifecycle was found in literature. This study utilized the Failure Modes and Effects Analysis as a convenient technique for determining, classifying and analyzing common failures in the municipal solid waste lifecycle. As a result, an appropriate risk scoring of severity, occurrence, and detection of failure modes and computing the Risk Priority Number for identifying the high potential failure modes were made. Nineteen failure modes were identified, and nine of them were ranked as the priority items for improvement. Recommended actions for all failure modes were suggested. Occurrences of failures were remarkably reduced after implementing the procedure for six months. The results of this study have minimized potential failures and brought continuous improvement, thus achieving a better protection of the environment. PMID:26372404

  7. Fractographic ceramic failure analysis using the replica technique

    PubMed Central

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

    2007-01-01

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

  8. 76 FR 2908 - Nonprofit Management LLC and Jeremy Ryan Claeys; Analysis of Proposed Consent Order To Aid Public...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-18

    ... Nonprofit Management LLC and Jeremy Ryan Claeys; Analysis of Proposed Consent Order To Aid Public Comment... or unfair methods of competition. The attached Analysis to Aid Public Comment describes both the... following Analysis to Aid Public Comment describes the terms of the consent agreement, and the...

  9. 75 FR 56538 - Air Products and Chemicals, Inc.; Analysis of Proposed Agreement Containing Consent Orders to Aid...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-16

    ... Products and Chemicals, Inc.; Analysis of Proposed Agreement Containing Consent Orders to Aid Public... practices or unfair methods of competition. The attached Analysis to Aid Public Comment describes both the... period of thirty (30) days. The following Analysis to Aid Public Comment describes the terms of...

  10. 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.

  11. Analysis of electronic component failures using high-density radiography

    SciTech Connect

    Tuohig, W.D.; Potter, T.J.

    1991-11-01

    The exceptional resolution and nondestructive nature of microfocus radiography has proven to be extremely useful in the diagnosis of electronic component failures, particularly when the components are contained in sealed or encapsulated assemblies. An epoxy-encapsulated NTC thermistor and an epitaxial silicon P-N junction photodetector are examples of discrete devices in which the cause of failure was correctly hypothesized directly from a radiographic image. Subsequent destructive physical examinations confirmed the initial hypothesis and established the underlying cause in each case. The problem in a vacuum switch tube which failed to function was apparent in the radiographic image, but the underlying cause was not clear. However, radiography also showed that the position of a flat cable in the assembly could contribute to failure, an observation which resulted in a change in manufacturing procedure. In each of these instances, microradiography played a key role in decisions concerning the root cause of failure, product viability, and corrective action. 15 refs., 10 figs.

  12. 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.

  13. 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.

  14. 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

  15. The AIDS epidemic and gay bathhouses: a constitutional analysis.

    PubMed

    Rabin, J A

    1986-01-01

    Some legal scholars propose that the right of privacy articulated by the United States Supreme Court should be extended to protect homosexual activity. In light of the advent of AIDS, should that extension include constitutional protection for homosexual men who frequent gay bathhouses? The author argues that although the government has the power to close the baths in the name of public health, it should not do so without careful and conscious balancing against the privacy rights infringed upon by its actions. Balancing the tension between public health policy and individual rights applies not only to the specific situation of the baths, but also to insurance companies' aim to test all single, young, male life and health policy applicants for exposure to the putative AIDS virus; to potential health department releases of names of those testing antibody-positive for HTLV-III; to the military's rumored plans to discharge all personnel suspected of having AIDS; and to school districts seeking to exclude children with AIDS.

  16. The political economy of AIDS leadership in developing countries: an exploratory analysis.

    PubMed

    Bor, Jacob

    2007-04-01

    The commitment of high-level government leaders is widely recognized as a key factor in curbing national AIDS epidemics. But where does such leadership come from? This paper presents a quantitative analysis of the determinants of AIDS leadership in 54 developing countries, using the 2003 AIDS Program Effort Index "political support" score as an indicator of political commitment. Explanatory variables include measures of political institutions as well as economic development and integration. Models developed in the analysis explain over half of the variation in commitment across the countries in the sample. In particular, press freedoms, income equality, and HIV prevalence stand out as determinants of political commitment.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, N.; Cheng, Y. M.

    2014-09-01

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

  2. [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.

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

    PubMed

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

    2007-08-01

    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.

  4. 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.

  5. 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

  6. AIDS, policy analysis, and the electorate: the role of schools of public health.

    PubMed

    Krieger, N; Lashof, J C

    1988-04-01

    Current debates concerning appropriate policy to combat the epidemic of acquired immunodeficiency syndrome (AIDS) have raised critical questions regarding the role that schools of public health and individual public health professionals should play, if any, in AIDS-related policy analysis and social advocacy. In the summer of 1986, the School of Public Health at the University of California at Berkeley initiated a telegram sent by the Deans of all 23 schools of public health to protest US Department of Justice AIDS policy and, in the subsequent fall, the school expanded its public educational role in an unprecedented manner by initiating and issuing, with California's other three schools of public health, a policy analysis of Proposition 64, the LaRouche AIDS Quarantine Initiative. That analysis exposed the proposition's fallacious claims regarding casual transmission of AIDS and served to educate the electorate on the likely public health impact of this deleterious legislation. Based on these experiences, and in light of ongoing national controversy regarding AIDS, we believe schools of public health have an important role to play in policy analysis, and individual public health professionals have a role to play in social advocacy.

  7. AIDS, policy analysis, and the electorate: the role of schools of public health.

    PubMed Central

    Krieger, N; Lashof, J C

    1988-01-01

    Current debates concerning appropriate policy to combat the epidemic of acquired immunodeficiency syndrome (AIDS) have raised critical questions regarding the role that schools of public health and individual public health professionals should play, if any, in AIDS-related policy analysis and social advocacy. In the summer of 1986, the School of Public Health at the University of California at Berkeley initiated a telegram sent by the Deans of all 23 schools of public health to protest US Department of Justice AIDS policy and, in the subsequent fall, the school expanded its public educational role in an unprecedented manner by initiating and issuing, with California's other three schools of public health, a policy analysis of Proposition 64, the LaRouche AIDS Quarantine Initiative. That analysis exposed the proposition's fallacious claims regarding casual transmission of AIDS and served to educate the electorate on the likely public health impact of this deleterious legislation. Based on these experiences, and in light of ongoing national controversy regarding AIDS, we believe schools of public health have an important role to play in policy analysis, and individual public health professionals have a role to play in social advocacy. PMID:3348472

  8. 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.

  9. 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…

  10. 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.

  11. 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

  12. 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.

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

    SciTech Connect

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

    2007-09-01

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

  14. Experimental and Computational Studies on Progressive Failure Analysis of Notched Cross-Ply CFRP Composite

    NASA Astrophysics Data System (ADS)

    Pham, Dinh Chi; Sun, Xiushan

    2012-09-01

    This work presents experimental and computational studies on progressive failure analysis of notched cross-ply carbon fiber reinforced polymer (CFRP) composite. The carbon/epoxy composite laminated with [90/0]s layup is tested using double-notched specimens loaded in tension. The load-displacement curve, failure load and damage patterns of all tested specimens are discussed. In addition, a numerical analysis approach based on material property degradation method (MPDM) and cohesive elements (CE) is illustrated to capture complex failure mechanisms and damage progression as observed in the tested specimens. The MPDM is used to model the in-plane failure of 90° plies and 0° plies while the cohesive elements are used to account for the delamination at the [90/0] interfaces. Different progressive failure models employing fracture mechanics, continuum mechanics and micromechanics of failure are presented based on the MPDM-CE approach. The failure analyses by these progressive models are performed and their predictions are compared with the experimental results of notched [90/0]s CFRP composite. Reasonably good agreement between experimental results and simulation results is obtained and it is shown that the MPDM-CE approach can effectively predict the progressive failure of double-notched [90/0]s composite laminate.

  15. 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. PMID:26617451

  16. 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.

  17. 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

  18. Failure modes effects and criticality analysis (FMECA) approach to the crystalline silicon photovoltaic module reliability assessment

    NASA Astrophysics Data System (ADS)

    Kuitche, Joseph M.; Tamizh-Mani, Govindasamy; Pan, Rong

    2011-09-01

    Traditional degradation or reliability analysis of photovoltaic (PV) modules has historically consisted of some combination of accelerated stress and field testing, including field deployment and monitoring of modules over long time periods, and analyzing commercial warranty returns. This has been effective in identifying failure mechanisms and developing stress tests that accelerate those failures. For example, BP Solar assessed the long term reliability of modules deployed outdoor and modules returned from the field in 2003; and presented the types of failures observed. Out of about 2 million modules, the total number of returns over nine year period was only 0.13%. An analysis on these returns resulted that 86% of the field failures were due to corrosion and cell or interconnect break. These failures were eliminated through extended thermal cycling and damp heat tests. Considering that these failures are observed even on modules that have successfully gone through conventional qualification tests, it is possible that known failure modes and mechanisms are not well understood. Moreover, when a defect is not easily identifiable, the existing accelerated tests might no longer be sufficient. Thus, a detailed study of all known failure modes existed in field test is essential. In this paper, we combine the physics of failure analysis with an empirical study of the field inspection data of PV modules deployed in Arizona to develop a FMECA model. This technique examines the failure rates of individual components of fielded modules, along with their severities and detectabilities, to determine the overall effect of a defect on the module's quality and reliability.

  19. 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.

  20. Geothermal steam muffler diffusers: the Geysers, California. Failure analysis report

    SciTech Connect

    McAlpin, R.; Ellis, P.F. II

    1980-04-01

    The primary failure mechanism for the T304 diffusers was chloride induced stress corrosion cracking (sec.) Once SCC had progressed to a certain point, high cycle corrosion/fatigue proceeded to the final fracture. Alteration of the environment to prevent SCC is not feasible. The existing environment will also cause sulfide stress cracking (SSC) in susceptible materials; therefore, alternate materials must resist SSC as well as SCC. The very large amplitude operational stresses make heat treatment to relieve residual fabrication stress questionable for the prevention of SCC. (MHR)

  1. Application of Interface Technology in Progressive Failure Analysis of Composite Panels

    NASA Technical Reports Server (NTRS)

    Sleight, D. W.; Lotts, C. G.

    2002-01-01

    A progressive failure analysis capability using interface technology is presented. The capability has been implemented in the COMET-AR finite element analysis code developed at the NASA Langley Research Center and is demonstrated on composite panels. The composite panels are analyzed for damage initiation and propagation from initial loading to final failure using a progressive failure analysis capability that includes both geometric and material nonlinearities. Progressive failure analyses are performed on conventional models and interface technology models of the composite panels. Analytical results and the computational effort of the analyses are compared for the conventional models and interface technology models. The analytical results predicted with the interface technology models are in good correlation with the analytical results using the conventional models, while significantly reducing the computational effort.

  2. 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…

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Using EHRs and Machine Learning for Heart Failure Survival Analysis

    PubMed Central

    Panahiazar, Maryam; Taslimitehrani, Vahid; Pereira, Naveen; Pathak, Jyotishman

    2016-01-01

    “Heart failure (HF) is a frequent health problem with high morbidity and mortality, increasing prevalence and escalating healthcare costs” [1]. By calculating a HF survival risk score based on patient-specific characteristics from Electronic Health Records (EHRs), we can identify high-risk patients and apply individualized treatment and healthy living choices to potentially reduce their mortality risk. The Seattle Heart Failure Model (SHFM) is one of the most popular models to calculate HF survival risk that uses multiple clinical variables to predict HF prognosis and also incorporates impact of HF therapy on patient outcomes. Although the SHFM has been validated across multiple cohorts [1–5], these studies were primarily done using clinical trials databases that do not reflect routine clinical care in the community. Further, the impact of contemporary therapeutic interventions, such as beta-blockers or defibrillators, was incorporated in SHFM by extrapolation from external trials. In this study, we assess the performance of SHFM using EHRs at Mayo Clinic, and sought to develop a risk prediction model using machine learning techiniques that applies routine clinical care data. Our results shows the models which were built using EHR data are more accurate (11% improvement in AUC) with the convenience of being more readily applicable in routine clinical care. Furthermore, we demonstrate that new predictive markers (such as co-morbidities) when incorporated into our models improve prognostic performance significantly (8% improvement in AUC). PMID:26262006

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Creep-fatigue induced failures are often observed in engineering components operating under high temperature and cyclic loading. Understanding the creep-fatigue damage process and identifying failure root cause are very important for preventing such failures and improving the lifetime of engineering components. Finite element analyses including a heat transfer analysis and a creep-fatigue analysis were conducted to model the cyclic thermal and mechanical process of a furnace roll in a continuous hot-dip coating line. Typically, the roll has a short life, <1 year, which has been a problem for a long time. The failure occurred in the weld joining an end bell to a roll shell and resulted in the complete 360° separation of the end bell from the roll shell. The heat transfer analysis was conducted to predict the temperature history of the roll by modeling heat convection from hot air inside the furnace. The creep-fatigue analysis was performed by inputting the predicted temperature history and applying mechanical loads. The analysis results showed that the failure was resulted from a creep-fatigue mechanism rather than a creep mechanism. The difference of material properties between the filler metal and the base metal is the root cause for the roll failure, which induces higher creep strain and stress in the interface between the weld and the HAZ.

  9. 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.

  10. Computer AIDS for Clinical Research Management and Control: General Analysis and Design

    PubMed Central

    Willard, Christopher G.; Gatewood, Laël C.; Ellis, Lynda B. M.

    1979-01-01

    Clinical research projects involve concurrent management of subjects, protocol, analysis and study. This complicated management problem could be aided by the use of computerized data systems. For most effective aid, such a system should consider all aspects of clinical research. We have analyzed clinical research tasks involving data collection, communication, and management and have used this task analysis to develop a system model for clinical research data management and control. The model deals with data control, study monitoring, user interfaces, report and analysis libraries, and study subject and support data bases. It may be used as a basis for computerized data system study and development. The model also indicates that the role of computerized systems in clinical research could be expanded into such areas as automatic report generation and control, process control aids, quality assurance monitoring, and study documentation.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Stress Assisted Corrosion in Boiler Tubes - Failure Analysis

    SciTech Connect

    Singh, Preet M; Pawel, Steven J; Yang, Dong; Mahmood, Jamshad

    2007-01-01

    Stress assisted corrosion (SAC) of carbon steel boiler tubes is one of the major causes of waterside failure in industrial boilers. SAC is a major concern for kraft recovery boilers in the pulp and paper industry as any water leak into the furnace can cause a smelt-water explosion in the boiler. Failed carbon steel boiler tubes from different kraft recovery boilers were examined to understand the role of carbon steel microstructure on crack initiation and SAC crack morphology. A number of carbon steel tubes showed a deep decarburized layer on the inner surface (water-touched) and also an unusually large grain size at the inner tube surface. SAC cracks were found to initiate in these areas with large-graineddecarburized microstructure. Tubes without such microstructure were also found to have SAC cracks. It was found that the decarburization and large grained microstructure may facilitate initiation and growth but is not necessary for SAC of carbon steel boiler tubes.

  16. 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.

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

    SciTech Connect

    Bartholomew, R.J.

    1981-01-01

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

  18. 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.

  19. 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.

  20. Pharmacodynamic population analysis in chronic renal failure using artificial neural networks--a comparative study.

    PubMed

    Gaweda, Adam E; Jacobs, Alfred A; Brier, Michael E; Zurada, Jacek M

    2003-01-01

    This work presents a pharmacodynamic population analysis in chronic renal failure patients using Artificial Neural Networks (ANNs). In pursuit of an effective and cost-efficient strategy for drug delivery in patients with renal failure, two different types of ANN are applied to perform drug dose-effect modeling and their performance compared. Applied in a clinical environment, such models will allow for prediction of patient response to the drug at the effect site and, subsequently, for adjusting the dosing regimen.

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  2. 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.

  3. 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

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

    PubMed

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

    2016-01-01

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

  5. Computer-aided-engineering system for modeling and analysis of ECLSS integration testing

    NASA Technical Reports Server (NTRS)

    Sepahban, Sonbol

    1987-01-01

    The accurate modeling and analysis of two-phase fluid networks found in environmental control and life support systems is presently undertaken by computer-aided engineering (CAE) techniques whose generalized fluid dynamics package can solve arbitrary flow networks. The CAE system for integrated test bed modeling and analysis will also furnish interfaces and subsystem/test-article mathematical models. Three-dimensional diagrams of the test bed are generated by the system after performing the requisite simulation and analysis.

  6. 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.

  7. QCT-based failure analysis of proximal femurs under various loading orientations.

    PubMed

    Mirzaei, Majid; Keshavarzian, Maziyar; Alavi, Fatemeh; Amiri, Pegah; Samiezadeh, Saeid

    2015-06-01

    In this paper, the variations of the failure strength and pattern of human proximal femur with loading orientation were analysed using a novel quantitative computed tomography (QCT)-based linear finite element (FE) method. The QCT images of 4 fresh-frozen femurs were directly converted into voxel-based finite element models for the analyses of the failure loads and patterns. A new geometrical reference system was used for the alignment of the mechanical loads on the femoral head. A new method was used for recognition and assortment of the high-risk elements using a strain energy-based measure. The FE results were validated with the experimental results of the same specimens and the results of similar case studies reported in the literature. The validated models were used for the computational investigation of the failure loads and patterns under 15 different loading conditions. A consistent variation of the failure loads and patterns was found for the 60 different analysed cases. Finally, it was shown that the proposed procedure can be used as a reliable tool for the failure analysis of proximal femurs, e.g. identification of the relevant loading directions for specific failure patterns, or determination of the loading conditions under which the proximal femurs are failure-prone. PMID:25731689

  8. IP Network Failure Identification Based on the Detailed Analysis of OSPF LSA Flooding

    NASA Astrophysics Data System (ADS)

    Hei, Yuichiro; Ogishi, Tomohiko; Ano, Shigehiro; Hasegawa, Toru

    It is important to monitor routing protocols to ensure IP networks and their operations can maintain sufficient level of stability and reliability because IP routing is an essential part of such networks. In this paper, we focus on Open Shortest Path First (OSPF), a widely deployed intra-domain routing protocol. Routers running OSPF advertise their link states on Link State Advertisements (LSAs) as soon as they detect changes in their link states. In IP network operations, it is important for operators to ascertain the location and type of a failure in order to deal with failures adequately. We therefore studied IP network failure identification based on the monitoring of OSPF LSAs. There are three issues to consider in regard to identifying network failures by monitoring LSAs. The first is that multiple LSAs are flooded by a single failure. The second is the LSA delay, and the third is that multiple failures may occur simultaneously. In this paper, we propose a method of network failure identification based on a detailed analysis of OSPF LSA flooding that takes into account the above three issues.

  9. 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

  10. A New Computer-Aided Technique for Qualitative Document Analysis

    ERIC Educational Resources Information Center

    Morris, David; Ecclesfield, Nigel

    2011-01-01

    The ever-increasing production of digital textual data in a wide variety of forms presents both opportunities and challenges to researchers. The opportunities derive from the rich availability of secondary data with which to work. The challenges are the familiar ones of lack of time and resources to undertake the analysis. The qualitative…

  11. Prioritizing groundwater remediation policies: a fuzzy compatibility analysis decision aid.

    PubMed

    Nasiri, Fuzhan; Huang, Gordon; Fuller, Norma

    2007-01-01

    The implementation of groundwater remediation strategies in contaminated areas includes not only a cost-benefit analysis and an environmental risk assessment but also another type of study called compatibility analysis. A compatibility analysis targets the interactions between remediation technologies and site characteristics, such as the types of active contaminants and their concentrations, soil composition and geological features, etc. The purpose of this analysis is to identify the most compatible remediation plan for the contaminated site. In this paper, we introduce a decision support system for the prioritization of remediation plans based on their estimated compatibility index. As this model receives data in terms of linguistic judgments and experts' opinions, we use fuzzy sets theory to deal with these uncertainties. First, we break down the concept of compatibility into the measurable factors. Then by using a multiple-attribute decision-making (MADM) outline, we compute a factorial, regional and overall compatibility indicator for each plan. Finally, by comparing these generated indicators, we rank the remediation policies.

  12. 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.

  13. 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.

  14. 76 FR 18762 - Google, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-04-05

    ... Google, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade Commission... submit written comments electronically or in paper form. Comments should refer to ``Google, File No. 102... release describing it. A comment filed in paper form should include the ``Google, File No. 102...

  15. 77 FR 59925 - CarePatrol, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION CarePatrol, Inc.; Analysis of Proposed Consent Order To Aid Public Comment Correction In notice document 2012-23412 appearing on pages 58837-58838 in the issue of Monday, September 24, 2012, make...

  16. 77 FR 59925 - ABCSP, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-01

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION ABCSP, Inc.; Analysis of Proposed Consent Order To Aid Public Comment Correction In notice document 2012-23413 appearing on pages 58838-58840 in the issue of Monday, September 24, 2012, make the...

  17. 76 FR 71564 - ScanScout, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-18

    ... ScanScout, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade... SUPPLEMENTARY INFORMATION section below. Write ``ScanScout, File No. 102 3185'' on your comment, and file your... Sec. 2.34 the Commission Rules of Practice, 16 CFR 2.34, notice is hereby given that the...

  18. 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...

  19. 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...

  20. 77 FR 63833 - Equifax Information Services LLC; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-10-17

    ... Equifax Information Services LLC; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal... INFORMATION section below. Write ``Equifax Info Services, File No. 102 3252'' on your comment and file your... from Equifax Information Services LLC (``Equifax''). The proposed consent order has been placed on...

  1. 77 FR 58838 - ABCSP, Inc.; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-09-24

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION ABCSP, Inc.; Analysis of Proposed Consent Order to Aid Public Comment AGENCY: Federal Trade Commission... deliver your comment to the following address: Federal Trade Commission, Office of the Secretary, Room...

  2. 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...

  3. 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 SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3310...

  4. 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 SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3310...

  5. 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 SERVICES (CONTINUED) MEDICAL DEVICES EAR, NOSE, AND THROAT DEVICES Prosthetic Devices § 874.3310...

  6. 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)

  7. 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…

  8. 76 FR 75883 - Facebook, Inc.; Analysis of Proposed Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-05

    ... Facebook, Inc.; Analysis of Proposed Consent Order To Aid Public Comment AGENCY: Federal Trade Commission... SUPPLEMENTARY INFORMATION section below. Write ``Facebook, File No. 092 3184'' on your comment, and file your... receive it on or before December 30, 2011. Write ``Facebook, File No. 092 3184'' on your comment....

  9. 75 FR 5322 - Indoor Tanning Association; Analysis of Proposed Consent Order to Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-02

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION Indoor Tanning Association; Analysis of Proposed Consent Order to Aid Public Comment AGENCY: Federal..., subject to final approval, an agreement containing a consent order from the Indoor Tanning...

  10. Decision Aid Tool and Ontology-Based Reasoning for Critical Infrastructure Vulnerabilities and Threats Analysis

    NASA Astrophysics Data System (ADS)

    Choraś, Michał; Flizikowski, Adam; Kozik, Rafał; Hołubowicz, Witold

    In this paper, a decision aid tool (DAT) for Critical Infrastructure threats analysis and ranking is presented. We propose the ontology-based approach that provides classification, relationships and reasoning about vulnerabilities and threats of the critical infrastructures. Our approach is a part of research within INSPIRE project for increasing security and protection through infrastructure resilience.

  11. 78 FR 45194 - General Electric Company; Analysis of Proposed Agreement Containing Consent Order To Aid Public...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-26

    ... General Electric Company; Analysis of Proposed Agreement Containing Consent Order To Aid Public Comment... section below. Write ``General Electric, File No. 131 0069'' on your comment and file your comment online...'') with General Electric Company (``GE''), which is designed to remedy the anticompetitive effects of...

  12. 78 FR 24201 - Graco, Inc.; Analysis of Agreement Containing Consent Order To Aid Public Comment

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-04-24

    ... From the Federal Register Online via the Government Publishing Office FEDERAL TRADE COMMISSION Graco, Inc.; Analysis of Agreement Containing Consent Order To Aid Public Comment AGENCY: Federal Trade... comment on paper, mail or deliver your comment to the following address: Federal Trade Commission,...

  13. 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...

  14. 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....

  15. 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

  16. 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.

  17. 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. PMID:27282213

  18. 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.

  19. An analysis of the causes of failure in high chrome oxide refractory materials from slagging gasifiers

    SciTech Connect

    Bennett, James P.; Kwong, Kyei-Sing; Powell, Cynthia A.; Thomas, Hugh; Krabbe, Rick

    2006-01-01

    High Cr2O3 refractory materials are used to line the hot face of slagging gasifiers. Gasifiers are reaction chambers that convert water, oxygen, and a carbon feedstock into CO, H2, and methane at temperatures as high as 1575DGC and pressures up to 1000 psi. Ash in the carbon feedstock liquefies, erodes and corrodes the gasifier's refractory liner, contributing to liner failure within a few months to two years. The failure of a refractory liner decreases a gasifier's on-line availability and causes costly system downtime and repairs. Many factors contribute to refractory lining failure, including slag penetration and corrosion, thermal cycling, gasifier environment, and mechanical loads. The results of refractory post-mortem failure analysis and how observations relate to gasifier service life will be discussed.

  20. Analysis of the causes of failure in high chrome oxide refractory materials from slagging gasifiers

    SciTech Connect

    Bennett, J.P.; Kwong, K.-S.; Powell, C.A.; Thomas, H.; Krabbe, R.A.

    2006-03-01

    High Cr2O3 refractory materials are used to line the hot face of slagging gasifiers. Gasifiers are reaction chambers that convert water, oxygen, and a carbon feedstock into CO, H2, and methane at temperatures as high as 1575oC and pressures up to 1000 psi. Ash in the carbon feedstock liquefies, erodes and corrodes the gasifier’s refractory liner, contributing to liner failure within a few months to two years. The failure of a refractory liner decreases a gasifier’s on-line availability and causes costly system downtime and repairs. Many factors contribute to refractory lining failure, including slag penetration and corrosion, thermal cycling, gasifier environment, and mechanical loads. The results of refractory post-mortem failure analysis and how observations relate to gasifier service life will be discussed.

  1. An Efficient Adaptive Feedback cancellation using by Independent component analysis for hearing aids.

    PubMed

    Ji, Y S; Jung, S Y; Kwon, S Y; Kim, I Y; Kim, Sun; Lee, S M

    2005-01-01

    In this paper, we proposed a feedback cancellation algorithm based on independent component analysis (ICA) for digital hearing aids. In conventional adaptive feedback cancelling systems, the normalized least mean squares (NLMS) algorithm used to reduce acoustic feedback in which hearing aids occurs, generally at high gains. But primary input signal depend on the acoustic feedback signal in higher-order statistics, proposed algorithm was better acoustic feedback cancelling performance than the conventional NLMS algorithm when the input signal has a Laplacian distribution with high-order processing in real-time simulation of TMS320C 6711 DSK. PMID:17282799

  2. Using participant observation for organizational discovery and systems analysis: global AIDS program Uganda.

    PubMed

    Pina, Jamie

    2006-01-01

    Recent scaling up of HIV/AIDS treatment at one of the Global AIDS Program's (GAP) major partner organizations required the CDC's informatics team in Uganda to develop a clinical information system during a time of significant growth and change within the organization. Analysis of system utilization revealed numerous discrepancies between system functionality and the workflow of the clinic it was designed for. Participant observation was an effective data collection method for documenting the impact of the clinical information system on the organization, and for assessing the suitability of the system for the intended clinic.

  3. 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.

  4. 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).

  5. 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.

  6. 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).

  7. 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.

  8. 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.

  9. 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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27703506

  11. 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.

  12. 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

  13. Are country reputations for good and bad leadership on AIDS deserved? An exploratory quantitative analysis.

    PubMed

    Nattrass, Nicoli

    2008-12-01

    Some countries (e.g. Brazil) have good reputations on AIDS policy, whereas others, (notably South Africa) have been criticized for inadequate leadership. Cross-country regression analysis reveals that these 'poster children' for AIDS leadership have indeed performed better or worse than expected given their economic and institutional constraints and the demographic and health challenges facing them. Regressions were run on HAART coverage (number on highly active antiretroviral therapy as percentage of total need) and MTCTP coverage (pregnant HIV+ women accessing mother-to-child-transmission prevention services as percentage of total need). Brazil, Cambodia, Thailand and Uganda (all of whom have established reputations for good leadership on AIDS performed consistently better than expected-as did Burkina-Faso, Suriname, Paraguay Costa Rica, Mali and Namibia. South Africa, which has the worst reputation for AIDS leadership, performed significantly below expectations-as did Uruguay and Trinidad and Tobago. The paper thus confirms much of the conventional wisdom on AIDS leadership at country level and suggests new areas for research.

  14. 48 CFR 2937.103-70 - Department of Labor checklist to aid analysis and review of requirements for service contracts.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... checklist to aid analysis and review of requirements for service contracts. 2937.103-70 Section 2937.103-70 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS SERVICE CONTRACTING Service Contracts-General 2937.103-70 Department of Labor checklist to aid analysis and review...

  15. 48 CFR 2937.103-70 - Department of Labor checklist to aid analysis and review of requirements for service contracts.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... checklist to aid analysis and review of requirements for service contracts. 2937.103-70 Section 2937.103-70 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS SERVICE CONTRACTING Service Contracts-General 2937.103-70 Department of Labor checklist to aid analysis and review...

  16. 48 CFR 2937.103-70 - Department of Labor checklist to aid analysis and review of requirements for service contracts.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... checklist to aid analysis and review of requirements for service contracts. 2937.103-70 Section 2937.103-70 Federal Acquisition Regulations System DEPARTMENT OF LABOR GENERAL CONTRACTING REQUIREMENTS SERVICE CONTRACTING Service Contracts-General 2937.103-70 Department of Labor checklist to aid analysis and review...

  17. Sampling and analysis information aids for stationary source personnel

    SciTech Connect

    Jackson, M.D.; Johnson, L.D.

    1994-12-31

    The Environmental Protection Agency, in developing and evaluating samples and analysis methodology for stationary sources, has compiled information on availability and applicability of sampling and analytical methods. Information has also been summarized on the applicability of the gas chromatography/mass spectrometry as the analytical method. All of this information is accessible in three documents: ``Stationary Source Sampling and Analysis Directory, Version 2`` (SSSADIR), ``Handbook of GC/MS Data and Information for Selected Clean Air Act Amendments Compounds`` (Handbook), and ``Literature Review of CAAA Compounds`` (LitRev). The SSSADIR has information on which sampling and analytical methods to use for organic compounds listed in Title 3 of the Clean Air Act Amendments (CAAA) of 1990, as well as Appendices 8 and 9 of RCRA compounds, and the status of method evaluation for these analytes. The Handbook provides information on the mass spectra of selected CAAA analytes, primary quantitation ions, relative retention times and compatibility of the organic compounds in solution. The LitRev provides information on CAAA compounds for which EPA has no potential methods available but provides suggestions on ways to develop methods.

  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. 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.

  20. 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.

  1. 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

  2. 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

  3. 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.

  4. 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.

  5. Markov Chain Modelling Analysis of HIV/AIDS Progression: A Race-based Forecast in the United States.

    PubMed

    Lee, S; Ko, J; Tan, Xi; Patel, Isha; Balkrishnan, R; Chang, J

    2014-03-01

    HIV/AIDS has reached a pandemic level across the world with more than 33 million people who are living with HIV. In the United States, more than half a million people have been victims of AIDS. This study investigates the most vulnerable racial minority population (the African Americans) in the United States and the second least affected (the Caucasians) in order to predict the trends of the epidemic. A Markov chain analysis was used to model the progression of the disease among vulnerable people, infective people and AIDS cases for the two races separately, based on the 2009 Centers of Disease Control and Prevention HIV/AIDS Surveillance Report. Based on the Markov model, our study predicts that the number of African American people living with AIDS diagnosis and HIV infection and dead due to HIV/AIDS will be 662.2, 1225.3 and 62.9 in 2015 and 794.9, 1566.5 and 79.2 in 2030, respectively. The number of Caucasian people living with AIDS diagnosis and HIV infection and dead due to HIV/AIDS will be 96.4, 160 and 6.5 in 2015 and 118.6, 206.9 and 8.3 in 2030, respectively. The numbers of deaths due to HIV/AIDS are quite stable over the years in both the races. There is an increasing trend in the number of people living with HIV infection and AIDS diagnosis in Caucasians compared with African Americans. The absolute number of Caucasians living with AIDS diagnosis and HIV infection is quite smaller compared with African Americans. The results reveal discrepancy in HIV infection, AIDS diagnosis and deaths due to HIV/AIDS among the African Americans and the Caucasians races. There is a need for interventions focusing on HIV/AIDS prevention and management, optimum resource allocation and development of antiAIDS campaigns to reduce the infection rate. PMID:24843183

  6. Objective analysis of the singing voice as a training aid.

    PubMed

    Sangiorgi, T; Manfredi, C; Bruscaglioni, P

    2005-01-01

    A new tool for robust tracking of fundamental frequency is proposed, along with an objective measure of main singing voice parameters, such as vibrato rate, vibrato extent, and vocal intonation. High-resolution Power Spectral Density estimation is implemented, based on AutoRegressive models of suitable order, allowing reliable formant tracking also in vocalizations characterized by highly varying values. The proposed techniques are applied to about 1000 vocalizations, coming from both professional and non-professional singers, and show better performance as compared to classical Fourier-based approaches. If properly implemented, and with a user-friendly interface, the new tool would allow real-time analysis of singing voice. Hence, it could be of help in giving non-professional singers and singing teachers reliable measures of possible improvements during and after training. PMID:16287654

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

    PubMed

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

    2015-12-09

    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.

  8. Mechanism of failure of the Cabrol procedure: A computational fluid dynamic analysis.

    PubMed

    Poullis, M; Pullan, M

    2015-12-01

    Sudden failure of the Cabrol graft is common and frequently fatal. We utilised the technique of computational fluid dynamic (CFD) analysis to evaluate the mechanism of failure and potentially improve on the design of the Cabrol procedure. CFD analysis of the classic Cabrol procedure and a number of its variants was performed. Results from this analysis was utilised to generate further improved geometric options for the Cabrol procedure. These were also subjected to CFD analysis. All current Cabrol and variations of the Cabrol procedure are predicated by CFD analysis to be prone to graft thrombosis, secondary to stasis around the right coronary artery button. The right coronary artery flow characteristics were found to be the dominant reason for Cabrol graft failure. A simple modification of the Cabrol geometry is predicated to virtually eliminate any areas of blood stasis, and graft failure. Modification of the Cabrol graft geometry, due to CFD analysis may help reduce the incidence of graft thrombosis. A C shaped Cabrol graft with the right coronary button anastomosed to its side along its course from the aorta to the left coronary button is predicted to have the least thrombotic tendency. Clinical correlation is needed. PMID:26508722

  9. Mechanism of failure of the Cabrol procedure: A computational fluid dynamic analysis.

    PubMed

    Poullis, M; Pullan, M

    2015-12-01

    Sudden failure of the Cabrol graft is common and frequently fatal. We utilised the technique of computational fluid dynamic (CFD) analysis to evaluate the mechanism of failure and potentially improve on the design of the Cabrol procedure. CFD analysis of the classic Cabrol procedure and a number of its variants was performed. Results from this analysis was utilised to generate further improved geometric options for the Cabrol procedure. These were also subjected to CFD analysis. All current Cabrol and variations of the Cabrol procedure are predicated by CFD analysis to be prone to graft thrombosis, secondary to stasis around the right coronary artery button. The right coronary artery flow characteristics were found to be the dominant reason for Cabrol graft failure. A simple modification of the Cabrol geometry is predicated to virtually eliminate any areas of blood stasis, and graft failure. Modification of the Cabrol graft geometry, due to CFD analysis may help reduce the incidence of graft thrombosis. A C shaped Cabrol graft with the right coronary button anastomosed to its side along its course from the aorta to the left coronary button is predicted to have the least thrombotic tendency. Clinical correlation is needed.

  10. Methods for trend analysis: Examples with problem/failure data

    NASA Technical Reports Server (NTRS)

    Church, Curtis K.

    1989-01-01

    Statistics are emphasized as an important role in quality control and reliability. Consequently, Trend Analysis Techniques recommended a variety of statistical methodologies that could be applied to time series data. The major goal of the working handbook, using data from the MSFC Problem Assessment System, is to illustrate some of the techniques in the NASA standard, some different techniques, and to notice patterns of data. Techniques for trend estimation used are: regression (exponential, power, reciprocal, straight line) and Kendall's rank correlation coefficient. The important details of a statistical strategy for estimating a trend component are covered in the examples. However, careful analysis and interpretation is necessary because of small samples and frequent zero problem reports in a given time period. Further investigations to deal with these issues are being conducted.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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

  16. Failure mechanism analysis under compression loading of unidirectional carbon/epoxy composites using micromechanical modelling

    NASA Astrophysics Data System (ADS)

    Effendi, R. R.; Barrau, J.-J.; Guedra-Degeorges, D.

    An experimental study of the compression fracture of unidirectional composites (T300/914, T800/5245C, M40J/913, GY70/V108 and AS4/PEEK) shows that fiber kinking is the main failure mode. All materials tested exhibited a non-linear elastic behavior characterized by a continuous decrease of the tangent modulus as soon as the load was applied. A micromechanical model taking into account initial geometric imperfections was developed. Stress evolution in the constituents was analysed and then compared with their strength. Two failure modes were distinguished: failure due to the fracture of fibers and failure due to the fracture of matrix. This model demonstrates that the non-linear behavior is not due to the initial geometric imperfections. To refine modelling, a numerical analysis using a finite element method with elastoplastic and large displacement hypothesis was developed. This model not only shows the principals governing failure parameters: initial geometric impertions, yield stress of matrix and fiber compressive strength, but also demonstrates two failure mechanisms: fracture of fibers in compression and fiber kinking. This model confirms that the non-linear behavior is not attributed to the initial geometric imperfections.

  17. 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.

  18. 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

  19. Shell stability analysis in a computer aided engineering (CAE) environment

    NASA Technical Reports Server (NTRS)

    Arbocz, J.; Hol, J. M. A. M.

    1993-01-01

    The development of 'DISDECO', the Delft Interactive Shell DEsign COde is described. The purpose of this project is to make the accumulated theoretical, numerical and practical knowledge of the last 25 years or so readily accessible to users interested in the analysis of buckling sensitive structures. With this open ended, hierarchical, interactive computer code the user can access from his workstation successively programs of increasing complexity. The computational modules currently operational in DISDECO provide the prospective user with facilities to calculate the critical buckling loads of stiffened anisotropic shells under combined loading, to investigate the effects the various types of boundary conditions will have on the critical load, and to get a complete picture of the degrading effects the different shapes of possible initial imperfections might cause, all in one interactive session. Once a design is finalized, its collapse load can be verified by running a large refined model remotely from behind the workstation with one of the current generation 2-dimensional codes, with advanced capabilities to handle both geometric and material nonlinearities.

  20. 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.

  1. 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

  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. A meta-analysis of estimates of the AIDS incubation distribution.

    PubMed

    Cooley, P C; Myers, L E; Hamill, D N

    1996-06-01

    Information from 12 studies is combined to estimate the AIDS incubation distribution with greater precision than is possible from a single study. The analysis uses a hierarchy of parametric models based on a four-parameter generalized F distribution. This general model contains four standard two-parameter distributions as special cases. The cases are the Weibull, gamma, log-logistic, lognormal distributions. These four special cases subsume three distinct asymptotic hazard behaviors. As time increases beyond the median of approximately 10 years, the hazard can increase to infinity (Weibull), can plateau at some constant level (gamma), or can decrease to zero (log-logistic and lognormal). The Weibull, gamma and 'log-logistic distributions' which represent the three distinct asymptotic hazard behaviors, all fit the data as well as the generalized F distribution at the 25 percent significance level. Hence, we conclude that incubation data is still too limited to ascertain the specific hazard assumption that should be utilized in studies of the AIDS epidemic. Accordingly, efforts to model the AIDS epidemic (e.g., back-calculation approaches) should allow the incubation distribution to take several forms to adequately represent HIV estimation uncertainty. It is recommended that, at a minimum, the specific Weibull, gamma and log-logistic distributions estimated in this meta-analysis should all be used in modeling the AIDS epidemic, to reflect this uncertainty.

  5. Mathematical analysis of a two strain HIV/AIDS model with antiretroviral treatment.

    PubMed

    Bhunu, C P; Garira, W; Magombedze, G

    2009-09-01

    A two strain HIV/AIDS model with treatment which allows AIDS patients with sensitive HIV-strain to undergo amelioration is presented as a system of non-linear ordinary differential equations. The disease-free equilibrium is shown to be globally asymptotically stable when the associated epidemic threshold known as the basic reproduction number for the model is less than unity. The centre manifold theory is used to show that the sensitive HIV-strain only and resistant HIV-strain only endemic equilibria are locally asymptotically stable when the associated reproduction numbers are greater than unity. Qualitative analysis of the model including positivity, boundedness and persistence of solutions are presented. The model is numerically analysed to assess the effects of treatment with amelioration on the dynamics of a two strain HIV/AIDS model. Numerical simulations of the model show that the two strains co-exist whenever the reproduction numbers exceed unity. Further, treatment with amelioration may result in an increase in the total number of infective individuals (asymptomatic) but results in a decrease in the number of AIDS patients. Further, analysis of the reproduction numbers show that antiretroviral resistance increases with increase in antiretroviral use.

  6. 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

  7. 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)

  8. Rutherford backscattering analysis of the failure of chlorine anodes

    SciTech Connect

    Tilak, B.V.; Vallet, C.E.

    1996-06-01

    Rutherford Backscattering Spectrometry, carried out at the ORNL Surface Modification And Characterization Collaborative Research Center (SMAC) facility, has been applied to the nondestructive analysis of Ru02-Ti02 electrodes of 5000A, which mimic the DSA anodes in composition and the method of preparation. Occidental Chemical Corporation provided electrodes, which had been subjected to lifetime testing in H2S04 solution, for analysis by ORNL. The results were used to test the hypothesis of degradation of these, and similar electrodes, from a process involving a decrease in the Ru02:Ti02 ratio at and near the electrode surface and the related decrease in the electrode electrical conductivity. The drop in electrode activity is closely linked to a decrease in Ru content, and the measured profiles show that the loss takes place across the thin Ru02-Ti02 coating. No buildup of a pure Ti02 layer is apparent. The data agree quantitatively with the critical concentration previously reported by ORNL for materials produced by ion implantation and characterized by Rutherford Backscattering Spectrometry and Photoacoustic Spectrometry. The study has brought a better understanding of the degradation process in electrodes of great technological importance, and has given a more solid background in designing new fabrication procedures for improved electrodes.

  9. Predictors of Extubation Failure in Neurocritical Patients Identified by a Systematic Review and Meta-Analysis

    PubMed Central

    Huang, Kaibin; Lin, Zhenzhou; Qiao, Weiguang; Pan, Suyue

    2014-01-01

    Background Prediction of extubation failure, particularly in neurocritical patients, is unique and controversial. We conducted a systematic review and meta-analysis to identify the risk factors for extubation failure in these patients. Methods A literature search of databases (MEDLINE, EMBASE, the Cochrane Library, and Web of Science) was performed up to August of 2013 to identify trials that evaluated extubation failure predictors. Included trials were either prospective or retrospective cohort studies. Results Nine studies involving 928 participants were included. The systematic review and meta-analysis revealed that the following were predictive for extubation failure: pneumonia, atelectasis, mechanical ventilation of >24 h, a low Glasgow Coma Scale score (7–9T) (OR = 4.96, 95% CI = 1.61–15.26, P = 0.005), the inability to follow commands (OR = 2.07, 95% CI = 1.15–3.71, P = 0.02), especially the command to close the eyes, thick secretion, and no intact gag reflex. Meanwhile, the following were not predictive for extubation failure: sex, secretion volume, coughing upon suctioning, and the inability to follow one command among showing two fingers, wiggling the toes, or coughing on command. Additionally, some traditional weaning parameters were shown to poorly predict extubation failure in neurocritical patients. Conclusions Besides pneumonia, atelectasis, and the duration of mechanical ventilation, other factors that should be taken into consideration in the prediction of extubation failure when neurocritical patients are weaned from tracheal intubation include neurologic abilities (Glasgow Coma Scale score and following commands), the secretion texture, and the presence of a gag reflex. PMID:25486091

  10. 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.

  11. 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).

  12. Pushover analysis of reinforced concrete frames considering shear failure at beam-column joints

    NASA Astrophysics Data System (ADS)

    Sung, Y. C.; Lin, T. K.; Hsiao, C. C.; Lai, M. C.

    2013-09-01

    Since most current seismic capacity evaluations of reinforced concrete (RC) frame structures are implemented by either static pushover analysis (PA) or dynamic time history analysis, with diverse settings of the plastic hinges (PHs) on such main structural components as columns, beams and walls, the complex behavior of shear failure at beam-column joints (BCJs) during major earthquakes is commonly neglected. This study proposes new nonlinear PA procedures that consider shear failure at BCJs and seek to assess the actual damage to RC structures. Based on the specifications of FEMA-356, a simplified joint model composed of two nonlinear cross struts placed diagonally over the location of the plastic hinge is established, allowing a sophisticated PA to be performed. To verify the validity of this method, the analytical results for the capacity curves and the failure mechanism derived from three different full-size RC frames are compared with the experimental measurements. By considering shear failure at BCJs, the proposed nonlinear analytical procedures can be used to estimate the structural behavior of RC frames, including seismic capacity and the progressive failure sequence of joints, in a precise and effective manner.

  13. Health care failure mode and effect analysis: a useful proactive risk analysis in a pediatric oncology ward

    PubMed Central

    van Tilburg, C M; Leistikow, I P; Rademaker, C M A; Bierings, M B; van Dijk, A T H

    2006-01-01

    Background Pediatric inpatient settings are known for their high medication error rate. The aim of this study was to investigate whether the Health Care Failure Mode and Effect Analysis (HFMEA) is a valid proactive method to evaluate circumscribed health care processes like prescription up to and including administration of chemotherapy (vincristine) in the pediatric oncology inpatient setting. Methods A multidisciplinary team consisting of a team leader, pharmacy, nursing and medical staff and a patient's parent was assembled in a pediatric oncology ward with a computerized physician order entry system. A flow diagram of the process was made and potential failure modes were identified and evaluated using a hazard scoring matrix. Using a decision tree, it was determined for which failure mode recommendations had to be made. Results The process was divided into three main parts: prescription, processing by the pharmacy, and administration. Fourteen out of 61 failure modes were classified as high risk, 10 of which were sufficiently covered by current protocols. For the other four failure modes, five recommendations were made. Four additional recommendations were made concerning non‐high risk failure modes. Most of them were implemented by the hospital management. The whole process took seven meetings and a total of 140 man‐hours. Conclusions The systematic approach of HFMEA by a multidisciplinary team is a useful method for detecting failure modes. A patient or a parent of a patient contributes to the multidisciplinarity of the team. PMID:16456212

  14. HIV/AIDS and family support systems: A situation analysis of people living with HIV/AIDS in Lagos State.

    PubMed

    Oluwagbemiga, Adeyemi Ezekiel

    2007-11-01

    Current statistics about the HIV/AIDS epidemic in Nigeria do not reveal the broader social and economic impacts of the disease on the family.The study therefore primarily aimed to address the socio-economic effects of HIV infection on individuals and their families.The study was carried out in Lagos State. In-depth interviews were employed to collect information from 188 people living with HIV/AIDS through support groups in the state, while four focus group discussions were conducted to elicit information from people affected by AIDS about the socio-economic impacts of HIV/AIDS on families in Nigeria. From the survey, among people living with HIV/AIDS, 66% of females and males were in the age group 21-40 years, while 10% were older people above 60 years of age. Findings revealed that as HIV/AIDS strikes at parents, grand parents are assuming responsibility for bringing up the children of the infected persons and the orphans of those killed by the virus. It was striking that some of the older caregivers could not meet the requirement of these children.They are often forced to work more than they would have, or borrow in order to cope with the needs of these extra mouths. Some of the infected people have sold their properties to enable them to cope with the economic effects of the virus, while their children have had to drop out of school, since they could not afford the school fees and other related expenses. It was suggested that PLWHA should be economically empowered with adequate medical treatment, in order to reduce the impact of the disease on the family. PMID:18185894

  15. 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.

  16. 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. PMID:18091086

  17. Teaching Phonological Awareness to Students at Risk for Reading Failure: An Analysis of Four Instructional Programs.

    ERIC Educational Resources Information Center

    Wanzek, Jeanne; Dickson, Shirley; Bursuck, William D.; White, Jennifer M.

    2000-01-01

    The content of four phonological awareness training programs was analyzed according to six principles of effective instructional design related to teaching students at risk for reading failure. Analysis revealed that no program effectively included all six principles, implying that teachers need to adapt programs to improve their effectiveness.…

  18. 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.

  19. 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.

  20. 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. PMID:22514094

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  2. 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.

  3. 2. Freud's 'id' and Jung's 'self' as aids in self-analysis.

    PubMed

    Plaut, Alfred B J

    2005-02-01

    The id and the self are described as constructs of our unconscious which can be deployed in describing the analytic process. They can be used like the x in mathematics or the joker in a pack of cards as fitting in almost anywhere. But we can call on them as important aids to concentration, when additional room is made for meditating on the past which then comes to life again. They are useful for analysing ourselves and others. In this way the id as well as the self become aide-mémoires. The analysis of the repressed by means of the transference is not the only road to hitherto unconscious memories. This kind of meditation has helped me despite all reservations to undertake self-analysis and to write an autobiography. I maintain that one can have a transference to oneself. It is, of course, narcissistic. But then, no one can write an autobiography without a healthy dose of narcissism.

  4. 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

  5. "AID"-ing Academic Program Evaluation: The "Automatic Interaction Detector" as Analysis Tool. AIR 1984 Annual Forum Paper.

    ERIC Educational Resources Information Center

    Bloom, Allan M.; And Others

    The use of of the Automatic Interaction Detector (program AID3 of the OSIRIS statistical package) to study a university program is discussed. The performance of students who took general physics lecture and laboratory concurrently is compared to the performance of those who took them separately. Five years of data are analyzed, covering 1,997…

  6. 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.

  7. 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

  8. 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.

  9. Advancing lighting and daylighting simulation: The transition from analysis to design aid tools

    SciTech Connect

    Hitchcock, R.J.

    1995-05-01

    This paper explores three significant software development requirements for making the transition from stand-alone lighting simulation/analysis tools to simulation-based design aid tools. These requirements include specialized lighting simulation engines, facilitated methods for creating detailed simulatable building descriptions, an automated techniques for providing lighting design guidance. Initial computer implementations meant to address each of these requirements are discussed to further elaborate these requirements and to illustrate work-in-progress.

  10. Human Immunodeficiency Virus-1 Sequence Changes and Drug Resistance Mutation Among Virologic Failures of Lopinavir/Ritonavir Monotherapy: AIDS Clinical Trials Group Protocol A5230

    PubMed Central

    Vardhanabhuti, Saran; Katzenstein, David; Bartlett, John; Kumarasamy, Nagalingeswaran; Wallis, Carole L.

    2016-01-01

    Background. The mechanism of virologic failure (VF) of lopinavir/ritonavir (LPV/r) monotherapy is not well understood. We assessed sequence changes in human immunodeficiency virus-1 reverse-transcriptase (RT) and protease (PR) regions. Methods. Human immunodeficiency virus-1 pol sequences from 34 participants who failed second-line LPV/r monotherapy were obtained at study entry (SE) and VF. Sequence changes were evaluated using phylogenetic analysis and hamming distance. Results. Human immunodeficiency virus-1 sequence change was higher over drug resistance mutation (DRM) sites (median genetic distance, 2.2%; Q1 to Q3, 2.1%–2.5%) from SE to VF compared with non-DRM sites (median genetic distance, 1.3%; Q1 to Q3, 1.0%–1.4%; P < .0001). Evolution over DRM sites was mainly driven by changes in the RT (median genetic distance, 2.7%; Q1 to Q3, 2.2%–3.2%) compared with PR (median genetic distance, 1.1%; Q1 to Q3, 0.0%–1.1%; P < .0001). Most RT DRMs present at SE were lost at VF. At VF, 19 (56%) and 26 (76%) were susceptible to efavirenz/nevirapine and etravirine (ETV)/rilpivirine (RPV), respectively, compared with 1 (3%) and 12 (35%) at SE. Participants who retained nonnucleoside reverse-transcriptase inhibitor (NNRTI) DRMs and those without evolution of LPV/r DRMs had significantly shorter time to VF. Conclusions. The selection of LPV/r DRMs in participants with longer time to VF suggests better adherence and more selective pressure. Fading NNRTI mutations and an increase in genotypic susceptibility to ETV and RPV could allow for the reuse of NNRTI. Further studies are warranted to understand mechanisms of PR failure. PMID:27704010

  11. 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.

  12. Hygrothermal Analysis and Failure Analysis of Composite Beams under Moving Loads

    NASA Astrophysics Data System (ADS)

    Hanif, Moiz

    Excellent combination of high structural stiffness and low weight are the qualities of composite material leading to the extensive work on such materials. In order to achieve the desired performance requirements, the designer has to take into consideration the structural requirements and the functional characteristics. Thus, in this study, the effect of hygrothermal conditions on fiber reinforced composite laminates with moving loads have been extensively studied and has been carried out that accompanies Classical Laminate Plate Theory (CLPT) as well as First Order Shear Deformation Theory (FSDT) on MATLAB. A glass/epoxy composite system has been chosen for study with which similar results may be expected for other laminated composites. The hygrothermal effect is incorporated by adjusting the stiffness coefficients of the laminate to its level of moisture concentration using empirical relations. The failure analysis is done using the maximum normal stress criterion and the factor of safety for the lamina calculated and compared with respect to the corresponding maximum stresses and strengths. Different fiber volume fraction with varying fiber orientation of the plies in the laminate were modeled and studied. The results presented show the effect of stresses and strains in dry conditions, whereas for hygrothermal analysis, they also indicate that not all the laminates behave in a similar fashion and so it is possible by selecting the proper laminate configuration, the effect of moisture can be reduced. Also deducing, that due to hygrothermal effects, changes in the stiffness coefficients of a laminate do not appear to affect the deflection results significantly.

  13. 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. PMID:22179822

  14. 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.

  15. 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.

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

    NASA Technical Reports Server (NTRS)

    Subramani, Sujatha Srinivasan

    1990-01-01

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

  17. Direct likelihood inference and sensitivity analysis for competing risks regression with missing causes of failure.

    PubMed

    Moreno-Betancur, Margarita; Rey, Grégoire; Latouche, Aurélien

    2015-06-01

    Competing risks arise in the analysis of failure times when there is a distinction between different causes of failure. In many studies, it is difficult to obtain complete cause of failure information for all individuals. Thus, several authors have proposed strategies for semi-parametric modeling of competing risks when some causes of failure are missing under the missing at random (MAR) assumption. As many authors have stressed, while semi-parametric models are convenient, fully-parametric regression modeling of the cause-specific hazards (CSH) and cumulative incidence functions (CIF) may be of interest for prediction and is likely to contribute towards a fuller understanding of the time-dynamics of the competing risks mechanism. We propose a so-called "direct likelihood" approach for fitting fully-parametric regression models for these two functionals under MAR. The MAR assumption not being verifiable from the observed data, we propose an approach for performing sensitivity analyses to assess the robustness of inferences to departures from this assumption. The method relies on so-called "pattern-mixture models" from the missing data literature and was evaluated in a simulation study. This sensitivity analysis approach is applicable to various competing risks regression models (fully-parametric or semi-parametric, for the CSH or the CIF). We illustrate the proposed methods with the analysis of a breast cancer clinical trial, including suggestions for ad hoc graphical goodness-of-fit assessments under MAR.

  18. Failure analysis of thin-film amorphous-silicon solar-cell modules

    NASA Technical Reports Server (NTRS)

    Kim, Q.

    1984-01-01

    A failure analysis of thin film amorphous silicon solar cell modules was conducted. The purpose of this analysis is to provide information and data for appropriate corrective action that could result in improvements in product quality and reliability. Existing techniques were expanded in order to evaluate and characterize degradational performance of a-Si solar cells. Microscopic and macroscopic defects and flaws that significantly contribute to performance degradation were investigated.

  19. 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.

  20. Three-dimensional finite element progressive failure analysis of composite laminates under axial extension

    NASA Technical Reports Server (NTRS)

    Reddy, Yeruva S.; Reddy, Junuthula N.

    1993-01-01

    A three-dimensional (3D) progressive failure algorithm is developed, where the layerwise laminate theory (LWLT) of Reddy is used for kinematic description. The finite element model based on the layerwise theory predicts both inplane and interlaminar stresses with the same accuracy as that of a conventional 3D finite element model and provides a convenient format for modeling the 3D stress fields in composite laminates. A parametric study is conducted to investigate the effect of out-of-plane material properties, 3D stiffness reduction methods, and boundary conditions on the failure loads and strains of a composite laminate under axial extension. The results indicate that different parameters have a different degree of influence on the failure loads and strains. The predictive ability of various phenomenological failure criteria is evaluated in the light of experimental results available in the literature, and the predictions of the LWLT are compared with those of the first-order shear deformation theory. It is concluded that a 3D stress analysis is necessary to predict accurately the failure behavior of composite laminates.

  1. 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.

  2. Identifying and quantifying misclassified and under-reported AIDS deaths in Brazil: a retrospective analysis from 1985 to 2009

    PubMed Central

    Fazito, Erika; Cuchi, Paloma; Ma Fat, Doris; Ghys, Peter Denis; Pereira, Mauricio G; Vasconcelos, Ana Maria Nogales; Pascom, Ana Roberta Pati

    2012-01-01

    Background A retrospective analysis of deaths registered in the Brazilian Mortality System was conducted to quantify the under-reporting of HIV/AIDS deaths and those misclassified to AIDS-related conditions in the 15–49 years old population in Brazil. Methods Death rates for AIDS-related diseases were calculated by age and sex for 1985–2009. Changes in the age-sex-specific death rates over time were used to identify conditions likely to be misclassified AIDS deaths and to quantify the corresponding number of misclassified deaths. Deaths due to ill-defined causes were redistributed across all other natural causes of death. The resulting total number of AIDS deaths was further adjusted for incompleteness of the mortality reporting system. Results Out of the 28 potential causes of death investigated, five increased in the same distinct age pattern as AIDS: pneumonia, Kaposi's sarcoma, other immunodeficiencies, other septicaemia and toxoplasmosis. 18 490 deaths due to these five causes were recoded to HIV/AIDS from 1985 to 2009. 38 145 deaths due to ill-defined causes were redistributed to AIDS and 15 485 were added to the number of AIDS deaths to correct for completeness of the mortality system in Brazil. Altogether, 72 120 deaths were recoded to AIDS between 1985 and 2009 and added to the reported 194 445 AIDS related deaths in the country, representing 27% misclassification of AIDS deaths in Brazil. Conclusions This study demonstrated that AIDS mortality is underestimated by the official mortality information system in Brazil. Efforts need to be made to reduce misclassification of causes of death in the future and identify ways in which the confidentiality of information regarding cause of death can be maintained. PMID:23172349

  3. 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

  4. 77 FR 5857 - Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-06

    ... COMMISSION Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft...: On November 2, 2011 (76 FR 67764), the U.S. Nuclear Regulatory Commission (NRC) published for public comment Draft NUREG, ``Common- Cause Failure Analysis in Event and Condition Assessment: Guidance...

  5. 76 FR 67764 - Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-02

    ... COMMISSION Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and Research, Draft...-xxxx, Revision 0, ``Common-Cause Failure Analysis in Event and Condition Assessment: Guidance and...-0254 in the subject line of your comments. For additional instructions on submitting comments...

  6. Testicular failure

    MedlinePlus

    ... LH . Your doctor may also order a semen analysis to examine the number of healthy sperm you are producing. Sometimes, an ultrasound of the testes will be ordered. Testicular failure and low testosterone level may be hard to ...

  7. 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.

  8. 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.

  9. 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.

  10. Meta-analysis of survival with the molecular adsorbent recirculating system for liver failure

    PubMed Central

    He, Guo-Lin; Feng, Lei; Duan, Chong-Yang; Hu, Xiang; Zhou, Chen-Jie; Cheng, Yuan; Pan, Ming-Xin; Gao, Yi

    2015-01-01

    This study aims to assess the treatment effects of the molecular adsorbent recirculating system (MARS) in patients with acute and acute-on-chronic liver failure. We searched MEDLINE, EMBASE, and the Cochrane Controlled Trials Registry database between January 1966 and January 2014. We included randomized controlled trials, which compared the treatment effects of MARS with standard medical treatment. Study quality assessed according to Consolidated Standards of Reporting Trials (CONSORT) criteria. The risk ratio was used as the effect-size measure according to a fixed-effects model. The search strategy revealed 72 clinical studies, 10 of which were randomized controlled trials that met the criteria and were included. Four addressed ALF (93 patients) and six addressed AOCLF (453 patients). The mean CONSORT score was 15 (range 10-20). By meta-analysis, MARS significantly improved survival in ALF (risk ratio 0.61; 95% CI 0.38, 0.97; P = 0.04). There was no significant survival benefit in AOCLF (risk ratio 0.88; 95% CI 0.74, 1.06; P = 0.16). MARS significantly improved survival in patients with acute liver failure, however, there is no evidence that it improved survival in patients with acute-on-chronic liver failure. In conclusion, the present meta-analysis indicates that MARS therapy can improve survival in patients with ALF. It is necessary to develop MARS treatment because of the increasing demand for liver transplantation and the risk of liver failure. PMID:26770295

  11. 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.

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

    SciTech Connect

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

    1980-10-01

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

  13. 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.

  14. Computer program for design and performance analysis of navigation-aid power systems

    NASA Technical Reports Server (NTRS)

    Weiner, H.; Wiener, P.; Williams, K.

    1976-01-01

    The paper examines the requirements, design rationale, operation, and verification of a computer program designated as design synthesis/performance analysis (DSPA) computer program, which is capable of performing all the calculations necessary to understand the overall characteristics of solar array/battery power systems for navigation-aid applications. Despite the uncertainties in the erratic solar array degradation data and the potential impact on actual battery behavior, verification of the DSPA is considered successful. The program is shown to have the capability of simulating the performance of solar array/battery navigation-aid power systems. It can also be used to synthesize power system designs and provide essential design and cost data.

  15. 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. PMID:15676770

  16. 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.

  17. 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

  18. 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”,

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

    PubMed

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

    2014-01-01

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

  20. 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.

  1. 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

  2. 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.

  3. 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

  4. 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.

  5. Texture feature analysis for prediction of postoperative liver failure prior to surgery

    NASA Astrophysics Data System (ADS)

    Simpson, Amber L.; Do, Richard K.; Parada, E. Patricia; Miga, Michael I.; Jarnagin, William R.

    2014-03-01

    Texture analysis of preoperative CT images of the liver is undertaken in this study. Standard texture features were extracted from portal-venous phase contrast-enhanced CT scans of 36 patients prior to major hepatic resection and correlated to postoperative liver failure. Differences between patients with and without postoperative liver failure were statistically significant for contrast (measure of local variation), correlation (linear dependency of gray levels on neighboring pixels), cluster prominence (asymmetry), and normalized inverse difference moment (local homogeneity). Though texture features have been used to diagnose and characterize lesions, to our knowledge, parenchymal statistical variation has not been quantified and studied. We demonstrate that texture analysis is a valuable tool for quantifying liver function prior to surgery, which may help to identify and change the preoperative management of patients at higher risk for overall morbidity.

  6. 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.

  7. Failure of the crossover pipes used in the PK-39-IIM boiler middle radiant part and a numerical analysis of the factors caused this failure

    NASA Astrophysics Data System (ADS)

    Baranov, V. N.; Gorb, A. A.; Nikolaev, S. F.

    2013-06-01

    The consequences resulting from an emergency failure of one subflow in the middle radiant part of a modernized PK-39-IIM boiler occurred during one of its first startups after the erection are presented. A numerical analysis of the factors that caused this failure is carried out. The calculation was carried out in accordance with the recommendations suggested in the standard method of hydraulic design. It is shown that at a load equal to 40% of its nominal value, increment of heat absorption in the subflow equal to 586 kJ/kg (140 kcal/kg), and heat absorption nonuniformity coefficient in the misaligned element equal to 1.5, the temperature of medium downstream of the subflow is equal to 670°C (operating conditions close to those under which the failure occurred).

  8. Analysis of in-service failures and advances in microstructural characterization. Microstructural science Volume 26

    SciTech Connect

    Abramovici, E.; Northwood, D.O.; Shehata, M.T.; Wylie, J.

    1999-01-01

    The contents include Analysis of In-Service Failures (tutorials, transportation industry, corrosion and materials degradation, electronic and advanced materials); 1998 Sorby Award Lecture by Kay Geels, Struers A/S (Metallographic Preparation from Sorby to the Present); Advances in Microstructural Characterization (characterization techniques using high resolution and focused ion beam, characterization of microstructural clustering and correlation with performance); Advanced Applications (advanced alloys and intermetallic compounds, plasma spray coatings and other surface coatings, corrosion, and materials degradation).

  9. 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).

  10. 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.

  11. Analysis of implant-failure predictors in the posterior maxilla: a retrospective study of 1395 implants.

    PubMed

    Pabst, Andreas Max; Walter, Christian; Ehbauer, Sebastian; Zwiener, Isabella; Ziebart, Thomas; Al-Nawas, Bilal; Klein, Marcus Oliver

    2015-04-01

    The aim of this study was to analyze predictors for dental implant failure in the posterior maxilla. A database was created to include patients being treated with dental implants posterior to the maxillary cuspids. Independent variables thought to be predictive of potential implant failure included (1) sinus elevation, (2) implant length, (3) implant diameter, (4) indication, (5) implant region, (6) timepoint of implant placement, (7) one-vs. two-stage augmentation, and (8) healing mode. Cox regression analysis was used to evaluate the influence of predictors 1-3 on implant failure as dependent variable. The predictors 4-9 were analyzed strictly descriptively. The final database included 592 patients with 1395 implants. The overall 1- and 5-year implant survival rates were 94.8% and 88.6%, respectively. The survival rates for sinus elevation vs. placement into native bone were 94.4% and 95.4%, respectively (p = 0.33). The survival rates for the short (<10 mm), the middle (10-13 mm) and the long implants (>13 mm) were 100%, 89% and 76.8%, respectively (middle-vs. long implants p = 0.62). The implant survival rates for the small- (<3.6 mm), the middle- (3.6-4.5 mm) and the wide diameter implants (>4.5 mm) were 92.5%, 87.9% and 89.6%, respectively (p = 0.0425). None of the parameters evaluated were identified as predictor of implant failure in the posterior maxilla.

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

    NASA Astrophysics Data System (ADS)

    Li, N.; Cheng, Y. M.

    2015-01-01

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

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Individual patient data meta-analysis of beta-blockers in heart failure: rationale and design

    PubMed Central

    2013-01-01

    Abstract The Beta-Blockers in Heart Failure Collaborative Group (BB-HF) was formed to obtain and analyze individual patient data from the major randomized controlled trials of beta-blockers in heart failure. Even though beta-blockers are an established treatment for heart failure, uptake is still sub-optimal. Further, the balance of efficacy and safety remains uncertain for common groups including older persons, women, those with impaired renal function and diabetes. Our aim is to provide clinicians with a thorough and definitive evidence-based assessment of these agents. We have identified 11 large randomized trials of beta-blockers versus placebo in heart failure and plan to meta-analyze the data on an individual patient level. In total, these trials have enrolled 18,630 patients. Uniquely, the BB-HF group has secured access to the individual data for all of these trials, with the participation of key investigators and pharmaceutical companies. Our principal objectives include deriving an overall estimate of efficacy for all-cause mortality and cardiovascular hospitalization. Importantly, we propose a statistically-robust sub-group assessment according to age, gender, diabetes and other key factors; analyses which are only achievable using an individual patient data meta-analysis. Further, we aim to provide an assessment of economic benefit and develop a risk model for the prognosis of patients with chronic heart failure. This paper outlines inclusion criteria, search strategies, outcome measures and planned statistical analyses. Trial registration Clinical trial registration information: http://clinicaltrials.gov/ct2/show/NCT00832442 PMID:23327629

  19. 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 2

  20. 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.

  1. 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…

  2. 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

  3. 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.

  4. 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. PMID:26983454

  5. 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

  6. 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 ...

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Interface load analysis for computer-aided design of below-knee prosthetic sockets.

    PubMed

    Reynolds, D P; Lord, M

    1992-07-01

    A finite-element analysis is made for the compression of soft tissues of the residual lower limb contained in a prosthetic socket. The analysis is relevant to static loading during stance in a patellar-tendon-bearing, below-knee design of socket. Values of Young's modulus are obtained experimentally for use in the model. One of the main objectives is to study the sensitivity of the loading to these values and also to other assumed conditions. Using direct pressure at the limb/socket interface and vertical stiffness as indicators, changes in material properties, socket alignment and socket rectification are investigated; assumptions about the frictional characteristic at the interface are seen to be critical in determination of load distribution. This type of analysis may provide the next stage of refinement for computer-aided socket design systems.

  13. 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

  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. Dietitian Aide.

    ERIC Educational Resources Information Center

    Texas Tech. Univ., Lubbock. School of Home Economics.

    This course of study for the dietitian aide is one of a series available for use by teacher-coordinators and students in Grade 11 and 12 home economics cooperative education programs. Based on job analysis interviews with health care facilities personnel, this course was prepared by teachers and Instructional Materials Center staff, field-tested,…

  17. 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.

  18. Differentiation of acute renal failure and chronic renal failure by 2-dimensional analysis of urinary dipeptidase versus serum creatinine.

    PubMed

    Lee, S H; Kang, B Y; We, J S; Park, S K; Park, H S

    1999-03-01

    The differential diagnosis of acute renal failure (ARF) and chronic renal failure (CRF) may be possible by measuring urinary dipeptidase (Udpase) activity and serum creatinine (Scr) concentration. When the mass test of 246 individuals was examined on a 2-dimensional plot of Udpase (y-axis) versus Scr (x-axis) with the data obtained from healthy volunteers (n = 189), ARF (n = 19) and CRF (n = 38) patients, the characteristic distribution of each group was obvious. It is summarized by the mean values of healthy volunteers (1.44 +/- 0.39 mg/dL, 1.19 (0.59 mU/mL), ARF (6.04 +/- 5.04 mg/dL, 0.12 +/- 0.08 mU/mL), and CRF patients (8.72 +/- 2.93 mg/dL, 0.81 +/- 0.44 mU/mL). The healthy volunteers are distributed along the y-axis and the ARF patients the x-axis, thus separating the two groups 90 degrees apart. The CRF patients are scattered away from both x-, and y-axis. This 2-dimensional approach is thought to be very useful for the differential diagnosis of ARF suggesting Udpase as a new member of the marker enzymes of renal disease.

  19. 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.

  20. 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. PMID:27203408

  1. 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.

  2. Adherence in paediatric renal failure and dialysis: an ethical analysis of nurses' attitudes and reported practice.

    PubMed

    Mellor, Joe Scott; Hulton, Sally-Anne; Draper, Heather

    2015-02-01

    Minors have difficulty adhering to the strict management regimen required whilst on renal dialysis for chronic renal failure. This leads to ethical tensions as healthcare professionals (HCPs) and parents try, in the minor's best interests, to ensure s/he adheres. All 11 dialysis nurses working in a large, regional paediatric dialysis unit were interviewed about their perceptions and management of non-adherence and the ethical issues this raised for them. Participants reported negative attitudes to non-adherence alongside sympathy and feelings of frustration. They discussed the competing responsibilities between nurses, parents and minors, and how responsibility ought to be transferred to the minor as s/he matures; the need for minors to take responsibility ahead of transferring to adult services; and, the process of transferring this responsibility. Our discussion concentrates on the ethical issues raised by the participants' reports of how they respond to non-adherence using persuasion and coercion. We consider how understandings of capacity, traditional individual autonomy, and willpower can be used to comprehend the issue of non-adherence. We consider the relational context in which the minor receives, and participates in, healthcare. This exposes the interdependent triad of relationships between HCP, parent and minor and aids understanding of how to provide care in an ethical way. Relational ethics is a useful alternative understanding for professionals reflecting upon how they define their obligations in this context.

  3. AIDS lymphomas.

    PubMed

    Middleton, G W; Lau, R K

    1992-01-01

    Chronically immunosuppressed individuals are susceptible to lymphoreticular tumors. Up to 15% of patients with congenital deficiencies such as ataxia=telangiectasia may develop malignancies, mainly high-grade B cell non=Hodgkin's lymphomas (NHLs). AIDS lymphomas are comprised of NHLs including Burkitt's lymphoma (BL) and primary cerebral lymphomas (PCLs). Almost 3% of all AIDS patients (2824 of 97,258 cases) developed NHL. Epstein-Barr virus (EBV) as a co-factor in AIDS lymphomagenesis has been studied: in 12 cases of 24 AIDS lymphomas EBV by DNA in situ hybridization was found. In an analysis of 6 primary cerebral lymphomas, .5 were positive for EBV DNA by Southern blotting. In Burkitt's lymphoma the characteristic genetic alteration affects the c-myc oncogene. In 1/3 of BL p53 mutations were found but none in the 43 NHLs suggesting that p53 mutations and c-myc activation act synergistically in the pathogenesis of these tumors. Cytotoxic agents dideoxyinosine, dideoxycytosine, and zidovudine may cause secondary neoplasia. 8 of 55 AIDS patients under zidovudine treatment developed high-grade lymphoma 23.8 months subsequently; recently doses were reduced. PCL was found in 21 of 90 patients. A 5.2 months survival was associated with combined treatment with cyclophosphamide, Oncovin (vincristine), methotrexate, etoposide, and cytosine arabinoside compared with 11.3 months with chemotherapy. Colony-stimulating factors (CSFs) alleviate drug-induced myelotoxicity and zidovudine-induced neutropenia, however, l8 of 11 patients receiving granulocyte-macrophage CSF developed hematological toxicity. Interleukine-2 produced by T-helper cells enhancing tumor cells cytotoxicity has been used in AIDS-associated cryptosporidial diarrhea and in 4 patients with AIDS lymphoma with modest response, but its stimulation of the HIV-infected substrate may increase viral proliferation.

  4. Failure of Polyethylene Inlays in Cementless Total Hip Arthroplasty: A Retrieval Analysis

    PubMed Central

    Lee, Christoph; Heisel, Christian; Thomsen, Marc; Bitsch, Rudi G.

    2016-01-01

    A retrieval analysis has been performed on 50 polyethylene inlays of cementless screw ring implants (Mecring, Mecron, Berlin, Germany) to investigate the failure mechanism of this specific open cup hip arthroplasty design that has shown a high clinical failure rate. Design-specific damage modes like rim creep, collar fatigue, and backside wear were assessed. Furthermore, the inlays were measured using a CMM to determine deformation. In 90% backside wear was observed and collar fatigue occurred in 68% of the cases. Rim creep was present in 38% of the polyethylene inlays. In 90% of the cases the cup opening diameter was 32.1 mm or less and 46% had a diameter less than 32 mm. It seems that creep and deformation of the polyethylene leads to a reduced diameter at the cup opening and consequently decreased clearance. To avoid this type of failure, polyethylene inlays should be supported at the back by the cup to reduce the risk of ongoing creep deformation. PMID:27660758

  5. 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.

  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 of Polyethylene Inlays in Cementless Total Hip Arthroplasty: A Retrieval Analysis

    PubMed Central

    Lee, Christoph; Heisel, Christian; Thomsen, Marc; Bitsch, Rudi G.

    2016-01-01

    A retrieval analysis has been performed on 50 polyethylene inlays of cementless screw ring implants (Mecring, Mecron, Berlin, Germany) to investigate the failure mechanism of this specific open cup hip arthroplasty design that has shown a high clinical failure rate. Design-specific damage modes like rim creep, collar fatigue, and backside wear were assessed. Furthermore, the inlays were measured using a CMM to determine deformation. In 90% backside wear was observed and collar fatigue occurred in 68% of the cases. Rim creep was present in 38% of the polyethylene inlays. In 90% of the cases the cup opening diameter was 32.1 mm or less and 46% had a diameter less than 32 mm. It seems that creep and deformation of the polyethylene leads to a reduced diameter at the cup opening and consequently decreased clearance. To avoid this type of failure, polyethylene inlays should be supported at the back by the cup to reduce the risk of ongoing creep deformation.

  8. Failure of Orthodontic Mini-implants by Patient Age, Sex, and Arch; Number of Primary Insertions; and Frequency of Reinsertions After Failure: An Analysis of the Implant Failure Rate and Patient Failure Rate.

    PubMed

    Kim, Jong-Wan; Lee, Nam-Ki; Sim, Hye-Young; Yun, Pil-Young; Lee, Jong-Ho

    2016-01-01

    This study aimed to analyze and compare the failure rate of orthodontic mini-implants (OMIs) in terms of the number of implants (implant failure rate [IFR]) and patients (patient failure rate [PFR]) according to the age, sex, and arch of the patients, the number of primary insertions, and frequency of reinsertions after failure. A total of 394 OMIs (1.2 mm in diameter; 7.0 mm in length) were inserted in 125 patients (24 male and 101 female, mean age 21.95 ± 7.60 years). IFR and PFR were evaluated according to the age and sex of the patient, the number of primary insertions, and the frequency of reinsertions after failure. PFR was 40.08% and IFR was 18.27% after the first insertions. PFR was higher than IFR regardless of the number of OMIs inserted. IFR increased with an increase in the frequency of reinsertions, reaching 66.67% after the fourth insertion, whereas PFR decreased to 25.00% after the second insertion and to 66.67% after the third and fourth insertions. The overall PFR and IFR were 40.80% and 19.29%, respectively. Although male patients, young patients, and location in the mandible showed higher PFR and IFR, there were no significant differences between PFR and IFR according to the sex, age, or arch. PFR was higher than IFR in this study, indicating that the treatment process could be more strongly affected by PFR than IFR. The failure rate can increase with the frequency of OMI reinsertions after failure. Sex, age, and arch may have no correlation with primary or recurrent OMI failure. PMID:27333014

  9. Failure of Orthodontic Mini-implants by Patient Age, Sex, and Arch; Number of Primary Insertions; and Frequency of Reinsertions After Failure: An Analysis of the Implant Failure Rate and Patient Failure Rate.

    PubMed

    Kim, Jong-Wan; Lee, Nam-Ki; Sim, Hye-Young; Yun, Pil-Young; Lee, Jong-Ho

    2016-01-01

    This study aimed to analyze and compare the failure rate of orthodontic mini-implants (OMIs) in terms of the number of implants (implant failure rate [IFR]) and patients (patient failure rate [PFR]) according to the age, sex, and arch of the patients, the number of primary insertions, and frequency of reinsertions after failure. A total of 394 OMIs (1.2 mm in diameter; 7.0 mm in length) were inserted in 125 patients (24 male and 101 female, mean age 21.95 ± 7.60 years). IFR and PFR were evaluated according to the age and sex of the patient, the number of primary insertions, and the frequency of reinsertions after failure. PFR was 40.08% and IFR was 18.27% after the first insertions. PFR was higher than IFR regardless of the number of OMIs inserted. IFR increased with an increase in the frequency of reinsertions, reaching 66.67% after the fourth insertion, whereas PFR decreased to 25.00% after the second insertion and to 66.67% after the third and fourth insertions. The overall PFR and IFR were 40.80% and 19.29%, respectively. Although male patients, young patients, and location in the mandible showed higher PFR and IFR, there were no significant differences between PFR and IFR according to the sex, age, or arch. PFR was higher than IFR in this study, indicating that the treatment process could be more strongly affected by PFR than IFR. The failure rate can increase with the frequency of OMI reinsertions after failure. Sex, age, and arch may have no correlation with primary or recurrent OMI failure.

  10. Computer-Aided Diagnosis and Quantification of Cirrhotic Livers Based on Morphological Analysis and Machine Learning

    PubMed Central

    Chen, Yen-Wei; Luo, Jie; Dong, Chunhua; Han, Xianhua; Tateyama, Tomoko; Furukawa, Akira; Kanasaki, Shuzo

    2013-01-01

    It is widely known that morphological changes of the liver and the spleen occur during the clinical course of chronic liver diseases. In this paper, we proposed a morphological analysis method based on statistical shape models (SSMs) of the liver and spleen for computer-aided diagnosis and quantification of the chronic liver. We constructed not only the liver SSM but also the spleen SSM and a joint SSM of the liver and the spleen for a morphologic analysis of the cirrhotic liver in CT images. The effective modes are selected based on both its accumulation contribution rate and its correlation with doctor's opinions (stage labels). We then learn a mapping function between the selected mode and the stage of chronic liver. The mapping function was used for diagnosis and staging of chronic liver diseases. PMID:24187579

  11. 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.

  12. The Recent Progress in Quantitative Medical Image Analysis for Computer Aided Diagnosis Systems

    PubMed Central

    Kim, Tae-Yun; Son, Jaebum

    2011-01-01

    Computer-aided diagnosis (CAD) has become one of the major research subjects in medical imaging and diagnostic radiology. Many different CAD schemes are being developed for use in the detection and/or characterization of various lesions found through various types of medical imaging. These imaging technologies employ conventional projection radiography, computed tomography, magnetic resonance imaging, ultrasonography, etc. In order to achieve a high performance level for a computerized diagnosis, it is important to employ effective image analysis techniques in the major steps of a CAD scheme. The main objective of this review is to attempt to introduce the diverse methods used for quantitative image analysis, and to provide a guide for clinicians. PMID:22084808

  13. Noninvasive spectral imaging of skin chromophores based on multiple regression analysis aided by Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Nishidate, Izumi; Wiswadarma, Aditya; Hase, Yota; Tanaka, Noriyuki; Maeda, Takaaki; Niizeki, Kyuichi; Aizu, Yoshihisa

    2011-08-01

    In order to visualize melanin and blood concentrations and oxygen saturation in human skin tissue, a simple imaging technique based on multispectral diffuse reflectance images acquired at six wavelengths (500, 520, 540, 560, 580 and 600nm) was developed. The technique utilizes multiple regression analysis aided by Monte Carlo simulation for diffuse reflectance spectra. Using the absorbance spectrum as a response variable and the extinction coefficients of melanin, oxygenated hemoglobin, and deoxygenated hemoglobin as predictor variables, multiple regression analysis provides regression coefficients. Concentrations of melanin and total blood are then determined from the regression coefficients using conversion vectors that are deduced numerically in advance, while oxygen saturation is obtained directly from the regression coefficients. Experiments with a tissue-like agar gel phantom validated the method. In vivo experiments with human skin of the human hand during upper limb occlusion and of the inner forearm exposed to UV irradiation demonstrated the ability of the method to evaluate physiological reactions of human skin tissue.

  14. Applicability of time-to-failure analysis to accelerated strain before earthquakes and volcanic eruptions

    NASA Astrophysics Data System (ADS)

    Main, Ian G.

    1999-12-01

    We examine quantitatively the ranges of applicability of the equation Ω=A+B[1-t/tf]m for predicting `system-sized' failure times tf in the Earth. In applications Ω is a proxy measure for strain or crack length, and A, B and the index m are model parameters determined by curve fitting. We consider constitutive rules derived from (a) Charles' law for subcritical crack growth; (b) Voight's equation; and (c) a simple percolation model, and show in each case that this equation holds only when m<0. When m>0, the general solution takes the form Ω=A+B[1+t/T]m, where T is a positive time constant, and no failure time can be defined. Reported values for volcanic precursors based on rate data are found to be within the range of applicability of time-to-failure analysis (m<0). The same applies to seismic moment release before earthquakes, at the expense of poor retrospective predictability of the time of the a posteriori-defined main shock. In contrast, reported values based on increasing cumulative Benioff strain occur in the region where a system-sized failure time cannot be defined (m>0 commonly m~0.3). We conclude on physical grounds that cumulative seismic moment is preferred as the most direct measure of seismic strain. If cumulative Benioff strain is to be retained on empirical grounds, then it is important that these data either be re-examined with the independent constraint m<0, or that for the case 0

  15. 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

  16. Failure Surface Analysis of Polyimide/Titanium Notched Coating Adhesion Specimens

    SciTech Connect

    GIUNTA,RACHEL K.; KANDER,RONALD G.

    2000-12-18

    Adhesively bonded joints of LaRC{trademark} PETI-5, a phenylethynyl-terminated polyimide, with chromic acid anodized titanium were fabricated and debonded interfacially. The adhesive-substrate failure surfaces were investigated using several surface analysis techniques. From Auger spectroscopy, field emission scanning electron microscopy, and atomic force microscopy studies, polymer appears to be penetrating the pores of the anodized substrate to a depth of approximately 100 nm. From x-ray photoelectron spectroscopy data, the polymer penetrating the pores appears to be in electrical contact with the titanium substrate, leading to differential charging. These analyses confirm that the polymer is becoming mechanically interlocked within the substrate surface.

  17. ANALYSIS OF MULTIVARIATE FAILURE TIME DATA USING MARGINAL PROPORTIONAL HAZARDS MODEL.

    PubMed

    Chen, Ying; Chen, Kani; Ying, Zhiliang

    2010-01-01

    The marginal proportional hazards model is an important tool in the analysis of multivariate failure time data in the presence of censoring. We propose a method of estimation via the linear combinations of martingale residuals. The estimation and inference procedures are easy to implement numerically. The estimation is generally more accurate than the existing pseudo-likelihood approach: the size of efficiency gain can be considerable in some cases, and the maximum relative efficiency in theory is infinite. Consistency and asymptotic normality are established. Empirical evidence in support of the theoretical claims is shown in simulation studies. PMID:24307815

  18. A Review of Healthcare Failure Mode and Effects Analysis (HFMEA) in Radiotherapy.

    PubMed

    Giardina, M; Cantone, M C; Tomarchio, E; Veronese, I

    2016-10-01

    This paper presents a review of risk analyses in radiotherapy (RT) processes carried out by using Healthcare Failure Mode Effect Analysis (HFMEA) methodology, a qualitative method that proactively identifies risks to patients and corrects medical errors before they occur. This literature review was performed to provide an overview of how to approach the development of HFMEA applications in modern RT procedures, comparing recently published research conducted to support proactive programs to identify risks. On the basis of the reviewed literature, the paper suggests HFMEA shortcomings that need to be addressed. PMID:27575344

  19. Fatigue among caregivers of chronic renal failure patients: a principal components analysis.

    PubMed

    Schneider, Robert A

    2003-12-01

    Quality of life for caregivers of ESRD patients has not been well addressed. The physical and psychological status of this overlooked group can be important in the recovery or adaptation of patients with chronic renal failure. One particular symptom of a reduced quality of life of such caregivers is that of fatigue. The study tested the reliability of both existing and newer fatigue measures. Measures with high reliability yielded a single construct of fatigue in a principal components analysis in this study of 99 caregivers. Implications for practice are addressed. Potential for further study is recommended. PMID:14730783

  20. Premature ovarian failure (POF) syndrome: towards the molecular clinical analysis of its genetic complexity.

    PubMed

    Fassnacht, W; Mempel, A; Strowitzki, T; Vogt, P H

    2006-01-01

    The Premature Ovarian Failure (POF) syndrome is a very heterogeneous clinical disorder due probably to the complex genetic networks controlling human folliculogenesis. Clinical subgroups of POF patients whose aetiology of ovarian failure is based on the same genetic factors are therefore difficult to establish. Some experimental evidence suggests that these genes might be clustered on the female sex chromosome in the POF1 and POF2 loci. This review is aimed to present an overview of the actual structural changes of the X chromosome causing POF, and to present a number of X and autosomal female fertility genes which are probably key genes in human folliculogenesis and are therefore prominent POF candidate genes. Towards the molecular analysis of their functional contribution to the genetic aetiology of POF in the clinic, an interdisciplinary scheme for their diagnostic analysis is presented in a pilot study focussed on chromosome analyses and the expression analysis of some major POF candidate genes (DAZL, DBX, FOXL2, INHalpha, GDF9, USP9X) in the leukocytes of 101 POF patients. It starts with a comprehensive and significantly improved clinical diagnostic program for this large and heterogeneous patient group.

  1. Student Financial Aid in Maryland: Programs, Trends, and Analysis. Postsecondary Education Research Reports.

    ERIC Educational Resources Information Center

    Breslin, Janice

    Trends in financial aid to students in Maryland colleges and universities are reported. Attention is directed to the distribution of different types of aid to undergraduate and graduate students, and financial aid awarded by type of institution. Characteristics of recipients of Guaranteed Student Loans, General State Scholarships, and Senatorial…

  2. 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…

  3. 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

  4. National Responses to HIV/AIDS and Non-Communicable Diseases in Developing Countries: Analysis of Strategic Parallels and Differences.

    PubMed

    Haregu, Tilahun Nigatu; Setswe, Geoffrey; Elliott, Julian; Oldenburg, Brian

    2014-03-26

    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 healthThis study explores the parallels and differences between national responses to HIV/AIDS and non-communicable diseases (NCDs). The identified

  5. 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.

  6. 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.

  7. 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.

  8. Molecular adsorbent recirculating system as artificial support therapy for liver failure: a meta-analysis.

    PubMed

    Vaid, Arjun; Chweich, Haval; Balk, Ethan M; Jaber, Bertrand L

    2012-01-01

    Molecular Adsorbent Recirculating System (MARS) is an artificial liver support system that has been developed for patients with liver failure until the liver regains function or as a bridge to transplantation. We conducted a meta-analysis to examine the efficacy of this promising therapy. We searched MEDLINE, EMBASE, and the Cochrane Registry of Controlled Trials databases, and abstracts from the proceedings of several scientific meetings. Patients with acute, acute on chronic, and hyperacute liver failure were included and we compared MARS with standard medical therapy. Randomized and nonrandomized controlled trials were included and Molecular Adsorbent Recirculating System was the intervention used. We evaluated net change in total bilirubin levels, improvement in hepatic encephalopathy and mortality. Nine randomized controlled trials and one nonrandomized controlled study met criteria and were included. By meta-analysis, MARS resulted in a significant decrease in total bilirubin levels (net change -7.0 mg/dl; 95% CI -10.4, -3.7; p < 0.001) and in an improvement in the West-Haven grade of hepatic encephalopathy (odds ratio [OR] 3.0; 95% CI 1.9, 5.0; p < 0.001). There was no beneficial effect on mortality (OR 0.91; 95% CI 0.64, 1.31; p = 0.62). The limitations of this study include a small sample size, an inability to blind with significant heterogeneity among studies, and variable definitions of liver failure. The Molecular Adsorbent Recirculating System is associated with a significant improvement in total bilirubin levels and hepatic encephalopathy but has no impact on survival. Large studies are required to assess the merit of this promising therapy on patient-centered outcomes. PMID:22210651

  9. Prophylactic antibiotic regimen and dental implant failure: a meta-analysis.

    PubMed

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

    2014-12-01

    The aim of this meta-analysis was to investigate whether there are any positive effects of prophylactic antibiotic regimen on implant failure rates and post-operative infection when performing dental implant treatment in healthy individuals. An electronic search without time or language restrictions was undertaken in March 2014. Eligibility criteria included clinical human studies, either randomised or not. The search strategy resulted in 14 publications. The I(2) statistic was used to express the percentage of the total variation across studies due to heterogeneity. The inverse variance method was used with a fixed- or random-effects model, depending on the heterogeneity. The estimates of relative effect were expressed in risk ratio (RR) with 95% confidence interval. Six studies were judged to be at high risk of bias, whereas one study was considered at moderate risk, and six studies were considered at low risk of bias. The test for overall effect showed that the difference between the procedures (use versus non-use of antibiotics) significantly affected the implant failure rates (P = 0.0002), with a RR of 0.55 (95% CI 0.41-0.75). The number needed to treat (NNT) to prevent one patient having an implant failure was 50 (95% CI 33-100). There were no apparent significant effects of prophylactic antibiotics on the occurrence of post-operative infections in healthy patients receiving implants (P = 0.520). A sensitivity analysis did not reveal difference when studies judged as having high risk of bias were not considered. The results have to be interpreted with caution due to the presence of several confounding factors in the included studies.

  10. 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.

  11. Pharmacodynamics of vecuronium in patients with and without renal failure: a meta-analysis.

    PubMed

    Beauvoir, C; Peray, P; Daures, J P; Peschaud, J L; D'Athis, F

    1993-08-01

    Eight trials comparing the effects of vecuronium in patients with either normal renal function or renal failure were subjected to a meta-analysis. Vecuronium doses were similar in the different trials, identical in the two patient groups of any given trial, and ranged from 0.05 to 0.14 mg.kg-1. Neuromuscular blockade was assessed by TOF or single twitch stimulation, and recorded by either mechanomyography or electromyography. Indices of blockade included onset time (from injection to maximal twitch depression), duration of action (from injection to recovery to 25% of control twitch) and 25-75% recovery index. Statistical analysis used Hedges method: effect size and variance were calculated for each relevant outcome, then the global effect size was estimated by pooling the effect sizes of each trial. Three separate meta-analyses were conducted. No differences were found either in onset time, or in recovery index between the two groups, whereas the duration of action was longer in the renal failure group. It is concluded that renal function is likely involved in the pharmacokinetic parameters of vecuronium.

  12. 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.

  13. Evaluation of marginal failures of dental composite restorations by acoustic emission analysis.

    PubMed

    Gu, Ja-Uk; Choi, Nak-Sam

    2013-01-01

    In this study, a nondestructive method based on acoustic emission (AE) analysis was developed to evaluate the marginal failure states of dental composite restorations. Three types of ring-shaped substrates, which were modeled after a Class I cavity, were prepared from polymethyl methacrylate, stainless steel, and human molar teeth. A bonding agent and a composite resin were applied to the ring-shaped substrates and cured by light exposure. At each time-interval measurement, the tooth substrate presented a higher number of AE hits than polymethyl methacrylate and steel substrates. Marginal disintegration estimations derived from cumulative AE hits and cumulative AE energy parameters showed that a signification portion of marginal gap formation was already realized within 1 min at the initial light-curing stage. Estimation based on cumulative AE energy gave a higher level of marginal failure than that based on AE hits. It was concluded that the AE analysis method developed in this study was a viable approach in predicting the clinical survival of dental composite restorations efficiently within a short test period.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. Computer-aided head film analysis: the University of California San Francisco method.

    PubMed

    Baumrind, S; Miller, D M

    1980-07-01

    Computer technology is already assuming an important role in the management of orthodontic practices. The next 10 years are likely to see expansion in computer usage into the areas of diagnosis, treatment planning, and treatment-record keeping. In the areas of diagnosis and treatment planning, one of the first problems to be attacked will be the automation of head film analysis. The problems of constructing computer-aided systems for this purpose are considered herein in the light of the authors' 10 years of experience in developing a similar system for research purposes. The need for building in methods for automatic detection and correction of gross errors is discussed and the authors' method for doing so is presented. The construction of a rudimentary machine-readable data base for research and clinical purposes is described.

  19. Computer-Aided Sperm Analysis (CASA) of sperm motility and hyperactivation.

    PubMed

    Mortimer, David; Mortimer, Sharon T

    2013-01-01

    Progressive motility is a vital functional characteristic of ejaculated human spermatozoa that governs their ability to penetrate into, and migrate through, both cervical mucus and the oocyte vestments, and ultimately fertilize the oocyte. A detailed protocol, based on the most common computer-aided sperm analysis (CASA) system with phase contrast microscope optics, is provided for performing reliable assessments of sperm movement pattern characteristics ("kinematics") in semen. The protocol can also be used with washed sperm suspensions where, in addition, the percentages of motile and progressively motile spermatozoa can also be derived. Using CASA technology it is also possible to identify biologically, and hence clinically, important subpopulations of spermatozoa (e.g., those in semen with good mucus-penetrating characteristics, or those showing hyperactivation when incubated under capacitating conditions) by applying multi-parametric definitions on a cell-by-cell basis.

  20. 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.