Science.gov

Sample records for feedwater system reliability

  1. Comparative assessment of selected PWR auxiliary feedwater system reliability analyses

    SciTech Connect

    Youngblood, R.; Fresco, A.; Papazoglou, I.A.; Tsao, J.

    1985-01-01

    This paper presents a sample of results obtained in reviewing utility submittals of Auxiliary Feedwater System reliability studies. These results are then used to illustrate a few general points regarding such studies. The submittals and reviews for operating license applications are quite significant in that they represent an application of probabilistic risk assessment techniques in the licensing process.

  2. Review of the Shearon Harris Unit 1 auxiliary feedwater system reliability analysis

    SciTech Connect

    Fresco, A.; Youngblood, R.; Papazoglou, I.A.

    1986-02-01

    This report presents the results of a review of the Auxiliary Feedwater System Reliability Analysis for the Shearon Harris Nuclear Power Plant (SHNPP) Unit 1. The objective of this report is to estimate the probability that the Auxiliary Feedwater System will fail to perform its mission for each of three different initiators: (1) loss of main feedwater with offsite power available, (2) loss of offsite power, (3) loss of all ac power except vital instrumentation and control 125-V dc/120-V ac power. The scope, methodology, and failure data are prescribed by NUREG-0611 for other Westinghouse plants.

  3. Review of the Vogtle Units 1 and 2 Auxiliary Feedwater System reliability analysis

    SciTech Connect

    Fresco, A.; Youngblood, R.; Papazoglou, I.A.

    1985-10-01

    This report presents the results of the review of the Auxiliary Feedwater System reliability analysis for the Vogtle Electric Generating Plant (VEGP) Units 1 and 2. The objective of this report is to estimate the probability that the Auxiliary Feedwater System will fail to perform its mission for each of three different initiators: (1) loss of main feedwater with offsite power available, (2) loss of offsite power, (3) loss of all ac power except vital instrumentation and control 125-V dc/120-V ac power. The scope, methodology, and failure data are prescribed by NUREG-0611, Appendix III. The results are compared with those obtained in NUREG-0611 for other Westinghouse plants.

  4. Review of the Seabrook Units 1 and 2 auxiliary feedwater system reliability analysis

    SciTech Connect

    Fresco, A.; Youngblood, R.; Papazoglou, I.A.

    1984-02-01

    This report presents the results of a review of the Emergency Feedwater System Reliability Analysis for Seabrook Nuclear Station Units 1 and 2. The objective of this report is to estimate the probability that the Emergency Feedwater System will fail to perform its mission for each of three different initiators: (1) loss of main feedwater with offsite power available, (2) loss of offsite power, (3) loss of all ac power except vital instrumentation and control 125 VDC/120 VAC power. The scope, methodology, and failure data are prescribed by NUREG-0611, Appendix III. The results are compared with those obtained in NUREG-0611 for other Westinghouse plants.

  5. Review of the Catawba Units 1 and 2 auxiliary feedwater system reliability analysis

    SciTech Connect

    Fresco, A.; Youngblood, R.; Papazoglou, I.A.

    1983-10-01

    This report presents the results of a review of the Auxiliary Feedwater System Reliability Analysis for Catawba Units 1 and 2. The objective of this report is to estimate the probability that the Auxiliary Feedwater System will fail to perform its mission for each of three different initiators: (1) loss of main feedwater with offsite power available, (2) loss of offsite power, (3) loss of all ac power except for vital instrumentation and control power. The scope, methodology, and failure data are prescribed by NUREG-0611, Appendix III. The results are compared with those obtained in NUREG-0611 for other Westinghouse plants.

  6. A Markov Model for Assessing the Reliability of a Digital Feedwater Control System

    SciTech Connect

    Chu,T.L.; Yue, M.; Martinez-Guridi, G.; Lehner, J.

    2009-02-11

    A Markov approach has been selected to represent and quantify the reliability model of a digital feedwater control system (DFWCS). The system state, i.e., whether a system fails or not, is determined by the status of the components that can be characterized by component failure modes. Starting from the system state that has no component failure, possible transitions out of it are all failure modes of all components in the system. Each additional component failure mode will formulate a different system state that may or may not be a system failure state. The Markov transition diagram is developed by strictly following the sequences of component failures (i.e., failure sequences) because the different orders of the same set of failures may affect the system in completely different ways. The formulation and quantification of the Markov model, together with the proposed FMEA (Failure Modes and Effects Analysis) approach, and the development of the supporting automated FMEA tool are considered the three major elements of a generic conceptual framework under which the reliability of digital systems can be assessed.

  7. Reliability evaluation of auxiliary feedwater system by mapping GO-FLOW models into Bayesian networks.

    PubMed

    Liu, Zengkai; Liu, Yonghong; Wu, Xinlei; Yang, Dongwei; Cai, Baoping; Zheng, Chao

    2016-09-01

    Bayesian network (BN) is a widely used formalism for representing uncertainty in probabilistic systems and it has become a popular tool in reliability engineering. The GO-FLOW method is a success-oriented system analysis technique and capable of evaluating system reliability and risk. To overcome the limitations of GO-FLOW method and add new method for BN model development, this paper presents a novel approach on constructing a BN from GO-FLOW model. GO-FLOW model involves with several discrete time points and some signals change at different time points. But it is a static system at one time point, which can be described with BN. Therefore, the developed BN with the proposed method in this paper is equivalent to GO-FLOW model at one time point. The equivalent BNs of the fourteen basic operators in the GO-FLOW methodology are developed. Then, the existing GO-FLOW models can be mapped into equivalent BNs on basis of the developed BNs of operators. A case of auxiliary feedwater system of a pressurized water reactor is used to illustrate the method. The results demonstrate that the GO-FLOW chart can be successfully mapped into equivalent BNs.

  8. Feedwater temperature control methods and systems

    DOEpatents

    Moen, Stephan Craig; Noonan, Jack Patrick; Saha, Pradip

    2014-04-22

    A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) is disclosed. The system, in accordance with an example embodiment of the present invention, may include a controller configured to control a power output level of the NCBWR by controlling a heating subsystem to adjust a temperature of feedwater flowing into an annulus of the NCBWR. The heating subsystem may include a steam diversion line configured to receive steam generated by a core of the NCBWR and a steam bypass valve configured to receive commands from the controller to control a flow of the steam in the steam diversion line, wherein the steam received by the steam diversion line has not passed through a turbine. Additional embodiments of the invention may include a feedwater bypass valve for controlling an amount of flow of the feedwater through a heater bypass line to the annulus.

  9. System Study: Auxiliary Feedwater 1998-2014

    SciTech Connect

    Schroeder, John Alton

    2015-12-01

    This report presents an unreliability evaluation of the auxiliary feedwater (AFW) system at 69 U.S. commercial nuclear power plants. Demand, run hours, and failure data from fiscal year 1998 through 2014 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10 year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing or decreasing trends were identified in the AFW results.

  10. System Study: Auxiliary Feedwater 1998–2013

    SciTech Connect

    Schroeder, John Alton

    2014-12-31

    This report presents an unreliability evaluation of the auxiliary feedwater (AFW) system at 69 U.S. commercial nuclear power plants. Demand, run hours, and failure data from fiscal year 1998 through 2013 for selected components were obtained from the Institute of Nuclear Power Operations (INPO) Consolidated Events Database (ICES). The unreliability results are trended for the most recent 10-year period, while yearly estimates for system unreliability are provided for the entire active period. No statistically significant increasing or decreasing trends were identified in the AFW results.

  11. The effects of parameter variation on MSET models of the Crystal River-3 feedwater flow system.

    SciTech Connect

    Miron, A.

    1998-04-01

    In this paper we develop further the results reported in Reference 1 to include a systematic study of the effects of varying MSET models and model parameters for the Crystal River-3 (CR) feedwater flow system The study used archived CR process computer files from November 1-December 15, 1993 that were provided by Florida Power Corporation engineers Fairman Bockhorst and Brook Julias. The results support the conclusion that an optimal MSET model, properly trained and deriving its inputs in real-time from no more than 25 of the sensor signals normally provided to a PWR plant process computer, should be able to reliably detect anomalous variations in the feedwater flow venturis of less than 0.1% and in the absence of a venturi sensor signal should be able to generate a virtual signal that will be within 0.1% of the correct value of the missing signal.

  12. Auxiliary feedwater system aging study. Volume 2, Phase 1: Follow-on study

    SciTech Connect

    Kueck, J.D.

    1993-07-01

    This report documents the results of a Phase I follow-on study of the Auxiliary Feedwater (AFW) System that has been conducted for the US Regulatory Commission`s Nuclear Plant Aging research Program. The Phase I study found a number of significant AFW System functions that are not being adequately tested by conventional test methods and some that are actually being degraded by conventional testing. Thus, it was decided that this follow-on study would focus on these testing omissions nd equipment degradation. The deficiencies in current monitoring and operating practice are categorized and evaluated. Areas of component degradation caused by current practice are discussed. Recommendations are made for improved diagnostic methods and test procedures.

  13. Auxiliary feedwater system risk-based inspection guide for the South Texas Project nuclear power plant

    SciTech Connect

    Bumgardner, J.D.; Nickolaus, J.R.; Moffitt, N.E.; Gore, B.F.; Vo, T.V.

    1993-12-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. South Texas Project was selected as a plant for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by the NRC inspectors in preparation of inspection plans addressing AFW risk important components at the South Texas Project plant.

  14. Auxiliary feedwater system risk-based inspection guide for the McGuire nuclear power plant

    SciTech Connect

    Bumgardner, J.D.; Lloyd, R.C.; Moffitt, N.E.; Gore, B.F.; Vo, T.V.

    1994-05-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. McGuire was selected as one of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the McGuire plant.

  15. Auxiliary feedwater system risk-based inspection guide for the H. B. Robinson nuclear power plant

    SciTech Connect

    Moffitt, N.E.; Lloyd, R.C.; Gore, B.F.; Vo, T.V.; Garner, L.W.

    1993-08-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. H. B. Robinson was selected as one of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the H. B. Robinson plant.

  16. Auxiliary feedwater system risk-based inspection guide for the Ginna Nuclear Power Plant

    SciTech Connect

    Pugh, R.; Gore, B.F.; Vo, T.V.; Moffitt, N.E. )

    1991-09-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Ginna was selected as the eighth plant for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the Ginna plant. 23 refs., 1 fig., 1 tab.

  17. Auxiliary feedwater system risk-based inspection guide for the Point Beach nuclear power plant

    SciTech Connect

    Lloyd, R C; Moffitt, N E; Gore, B F; Vo, T V; Vehec, T A

    1993-02-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Point Beach was selected as one of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRS. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the Point Beach plant.

  18. Auxiliary feedwater system risk-based inspection guide for the Byron and Braidwood nuclear power plants

    SciTech Connect

    Moffitt, N.E.; Gore, B.F.: Vo, T.V. )

    1991-07-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Byron and Braidwood were selected for the fourth study in this program. The produce of this effort is a prioritized listing of AFW failures which have occurred at the plants and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the Byron/Braidwood plants. 23 refs., 1 fig., 1 tab.

  19. Digital feedwater and recirculation flow control for GPUN Oyster Creek

    SciTech Connect

    Burjorjee, D. ); Gan, B. )

    1992-01-01

    This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of Canada Ltd.'s software platform running on dual, redundant, industrial-grade 386 computers with opto-isolated field input/output (I/O) accessed through a parallel bus. The feedwater controller controls three main feed regulating valves, two low flow regulating valves, and two block valves. The recirculation controller drives the five scoop positioners of the hydraulic couplers. The system also drives contacts that lock up the actuators on detecting an open circuit in their current loops.

  20. Thermal-hydraulic analysis for changing feedwater check valve leakage rate testing methodology

    SciTech Connect

    Fuller, R.; Harrell, J.

    1996-12-01

    The current design and testing requirements for the feedwater check valves (FWCVs) at the Grand Gulf Nuclear Station are established from original licensing requirements that necessitate extremely restrictive air testing with tight allowable leakage limits. As a direct result of these requirements, the original high endurance hard seats in the FWCVs were modified with elastomeric seals to provide a sealing surface capable of meeting the stringent air leakage limits. However, due to the relatively short functional life of the elastomeric seals compared to the hard seats, the overall reliability of the sealing function actually decreased. This degraded performance was exhibited by frequent seal failures and subsequent valve repairs. The original requirements were based on limited analysis and the belief that all of the high energy feedwater vaporized during the LOCA blowdown. These phenomena would have resulted in completely voided feedwater lines and thus a steam environment within the feedwater leak pathway. To challenge these criteria, a comprehensive design basis accident analysis was developed using the RELAP5/MOD3.1 thermal-hydraulic code. Realistic assumptions were used to more accurately model the post-accident fluid conditions within the feedwater system. The results of this analysis demonstrated that no leak path exists through the feedwater lines during the reactor blowdown phase and that sufficient subcooled water remains in various portions of the feedwater piping to form liquid water loop seals that effectively isolate this leak path. These results provided the bases for changing the leak testing requirements of the FWCVs from air to water. The analysis results also established more accurate allowable leakage limits, determined the real effective margins associated with the FWCV safety functions, and led to design changes that improved the overall functional performance of the valves.

  1. Emergency feedwater system risk-based inspection guide for the Arkansas Nuclear One Unit 2 Power Plant

    SciTech Connect

    Pugh, R.; Gore, B.F.; Vo, T.V.

    1992-09-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses-existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Arkansas Nuclear One Unit 2 was selected as one of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRS. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at the Arkansas Nuclear One Unit 2 plant.

  2. Auxiliary feedwater system risk-based inspection guide for the Beaver Valley, Units 1 and 2 nuclear power plants

    SciTech Connect

    Lloyd, R.C.; Vehec, T.A.; Moffitt, N.E.; Gore, B.F.; Vo, T.V.; Rossbach, L.W.; Sena, P.P. III

    1993-02-01

    In a study sponsored by the US Nuclear Regulatory Commission (NRC), Pacific Northwest Laboratory has developed and applied a methodology for deriving plant-specific risk-based inspection guidance for the auxiliary feedwater (AFW) system at pressurized water reactors that have not undergone probabilistic risk assessment (PRA). This methodology uses existing PRA results and plant operating experience information. Existing PRA-based inspection guidance information recently developed for the NRC for various plants was used to identify generic component failure modes. This information was then combined with plant-specific and industry-wide component information and failure data to identify failure modes and failure mechanisms for the AFW system at the selected plants. Beaver Valley Units 1 and 2 were selected as two of a series of plants for study. The product of this effort is a prioritized listing of AFW failures which have occurred at the plant and at other PWRs. This listing is intended for use by NRC inspectors in the preparation of inspection plans addressing AFW risk-important components at Beaver Valley Units 1 and 2.

  3. Theory of reliable systems

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.

    1975-01-01

    An attempt was made to refine the current notion of system reliability by identifying and investigating attributes of a system which are important to reliability considerations. Techniques which facilitate analysis of system reliability are included. Special attention was given to fault tolerance, diagnosability, and reconfigurability characteristics of systems.

  4. Removable feedwater sparger assembly

    DOEpatents

    Challberg, Roy C.

    1994-01-01

    A removable feedwater sparger assembly includes a sparger having an inlet pipe disposed in flow communication with the outlet end of a supply pipe. A tubular coupling includes an annular band fixedly joined to the sparger inlet pipe and a plurality of fingers extending from the band which are removably joined to a retention flange extending from the supply pipe for maintaining the sparger inlet pipe in flow communication with the supply pipe. The fingers are elastically deflectable for allowing engagement of the sparger inlet pipe with the supply pipe and for disengagement therewith.

  5. Hawaii electric system reliability.

    SciTech Connect

    Silva Monroy, Cesar Augusto; Loose, Verne William

    2012-09-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers' views of reliability %E2%80%9Cworth%E2%80%9D and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers' views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

  6. Hawaii Electric System Reliability

    SciTech Connect

    Loose, Verne William; Silva Monroy, Cesar Augusto

    2012-08-01

    This report addresses Hawaii electric system reliability issues; greater emphasis is placed on short-term reliability but resource adequacy is reviewed in reference to electric consumers’ views of reliability “worth” and the reserve capacity required to deliver that value. The report begins with a description of the Hawaii electric system to the extent permitted by publicly available data. Electrical engineering literature in the area of electric reliability is researched and briefly reviewed. North American Electric Reliability Corporation standards and measures for generation and transmission are reviewed and identified as to their appropriateness for various portions of the electric grid and for application in Hawaii. Analysis of frequency data supplied by the State of Hawaii Public Utilities Commission is presented together with comparison and contrast of performance of each of the systems for two years, 2010 and 2011. Literature tracing the development of reliability economics is reviewed and referenced. A method is explained for integrating system cost with outage cost to determine the optimal resource adequacy given customers’ views of the value contributed by reliable electric supply. The report concludes with findings and recommendations for reliability in the State of Hawaii.

  7. Multidisciplinary System Reliability Analysis

    NASA Technical Reports Server (NTRS)

    Mahadevan, Sankaran; Han, Song; Chamis, Christos C. (Technical Monitor)

    2001-01-01

    The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code, developed under the leadership of NASA Glenn Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multidisciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

  8. Technical feasibility study of a low-cost hybrid PAC-UF system for wastewater reclamation and reuse: a focus on feedwater production for low-pressure boilers.

    PubMed

    Amosa, Mutiu Kolade; Jami, Mohammed Saedi; Alkhatib, Ma'an Fahmi R; Majozi, Thokozani

    2016-11-01

    This study has applied the concept of the hybrid PAC-UF process in the treatment of the final effluent of the palm oil industry for reuse as feedwater for low-pressure boilers. In a bench-scale set-up, a low-cost empty fruit bunch-based powdered activated carbon (PAC) was employed for upstream adsorption of biotreated palm oil mill effluent (BPOME) with the process conditions: 60 g/L dose of PAC, 68 min of mixing time and 200 rpm of mixing speed, to reduce the feedwater strength, alleviate probable fouling of the membranes and thus improve the process flux (productivity). Three polyethersulfone ultrafiltration membranes of molecular weight cut-off (MWCO) of 1, 5 and 10 kDa were investigated in a cross-flow filtration mode, and under constant transmembrane pressures of 40, 80, and 120 kPa. The permeate qualities of the hybrid processes were evaluated, and it was found that the integrated process with the 1 kDa MWCO UF membrane yielded the best water quality that falls within the US EPA reuse standard for boiler-feed and cooling water. It was also observed that the permeate quality is fit for extended reuse as process water in the cement, petroleum and coal industries. In addition, the hybrid system's operation consumed 37.13 Wh m(-3) of energy at the highest applied pressure of 120 kPa, which is far lesser than the typical energy requirement range (0.8-1.0 kWh m(-3)) for such wastewater reclamation.

  9. Laser System Reliability

    DTIC Science & Technology

    1977-03-01

    NEALE CAPT. RANDALL D. GODFREY CAPT. JOHN E. ACTON HR. DAVE B. LEMMING (ASD) :,^ 19 . ••^w**** SECTION III RELIABILITY PREDICTION...Dete Exchange Program) failure rate date bank. In addition, some data have been obtained from Hughes. Rocketdyne , Garrett, and the AFWL’s APT Failure...Central Ave, Suite 306, Albuq, NM 87108 R/M Systems, Inc (Dr. K. Blemel), 10801 Lomas 81vd NE, Albuquerque, NM 87112 Rocketdyne 01 v, Rockwell

  10. Load Control System Reliability

    SciTech Connect

    Trudnowski, Daniel

    2015-04-03

    This report summarizes the results of the Load Control System Reliability project (DOE Award DE-FC26-06NT42750). The original grant was awarded to Montana Tech April 2006. Follow-on DOE awards and expansions to the project scope occurred August 2007, January 2009, April 2011, and April 2013. In addition to the DOE monies, the project also consisted of matching funds from the states of Montana and Wyoming. Project participants included Montana Tech; the University of Wyoming; Montana State University; NorthWestern Energy, Inc., and MSE. Research focused on two areas: real-time power-system load control methodologies; and, power-system measurement-based stability-assessment operation and control tools. The majority of effort was focused on area 2. Results from the research includes: development of fundamental power-system dynamic concepts, control schemes, and signal-processing algorithms; many papers (including two prize papers) in leading journals and conferences and leadership of IEEE activities; one patent; participation in major actual-system testing in the western North American power system; prototype power-system operation and control software installed and tested at three major North American control centers; and, the incubation of a new commercial-grade operation and control software tool. Work under this grant certainly supported the DOE-OE goals in the area of “Real Time Grid Reliability Management.”

  11. Ultimately Reliable Pyrotechnic Systems

    NASA Technical Reports Server (NTRS)

    Scott, John H.; Hinkel, Todd

    2015-01-01

    This paper presents the methods by which NASA has designed, built, tested, and certified pyrotechnic devices for high reliability operation in extreme environments and illustrates the potential applications in the oil and gas industry. NASA's extremely successful application of pyrotechnics is built upon documented procedures and test methods that have been maintained and developed since the Apollo Program. Standards are managed and rigorously enforced for performance margins, redundancy, lot sampling, and personnel safety. The pyrotechnics utilized in spacecraft include such devices as small initiators and detonators with the power of a shotgun shell, detonating cord systems for explosive energy transfer across many feet, precision linear shaped charges for breaking structural membranes, and booster charges to actuate valves and pistons. NASA's pyrotechnics program is one of the more successful in the history of Human Spaceflight. No pyrotechnic device developed in accordance with NASA's Human Spaceflight standards has ever failed in flight use. NASA's pyrotechnic initiators work reliably in temperatures as low as -420 F. Each of the 135 Space Shuttle flights fired 102 of these initiators, some setting off multiple pyrotechnic devices, with never a failure. The recent landing on Mars of the Opportunity rover fired 174 of NASA's pyrotechnic initiators to complete the famous '7 minutes of terror.' Even after traveling through extreme radiation and thermal environments on the way to Mars, every one of them worked. These initiators have fired on the surface of Titan. NASA's design controls, procedures, and processes produce the most reliable pyrotechnics in the world. Application of pyrotechnics designed and procured in this manner could enable the energy industry's emergency equipment, such as shutoff valves and deep-sea blowout preventers, to be left in place for years in extreme environments and still be relied upon to function when needed, thus greatly enhancing

  12. Space Shuttle Propulsion System Reliability

    NASA Technical Reports Server (NTRS)

    Welzyn, Ken; VanHooser, Katherine; Moore, Dennis; Wood, David

    2011-01-01

    This session includes the following sessions: (1) External Tank (ET) System Reliability and Lessons, (2) Space Shuttle Main Engine (SSME), Reliability Validated by a Million Seconds of Testing, (3) Reusable Solid Rocket Motor (RSRM) Reliability via Process Control, and (4) Solid Rocket Booster (SRB) Reliability via Acceptance and Testing.

  13. Calculating system reliability with SRFYDO

    SciTech Connect

    Morzinski, Jerome; Anderson - Cook, Christine M; Klamann, Richard M

    2010-01-01

    SRFYDO is a process for estimating reliability of complex systems. Using information from all applicable sources, including full-system (flight) data, component test data, and expert (engineering) judgment, SRFYDO produces reliability estimates and predictions. It is appropriate for series systems with possibly several versions of the system which share some common components. It models reliability as a function of age and up to 2 other lifecycle (usage) covariates. Initial output from its Exploratory Data Analysis mode consists of plots and numerical summaries so that the user can check data entry and model assumptions, and help determine a final form for the system model. The System Reliability mode runs a complete reliability calculation using Bayesian methodology. This mode produces results that estimate reliability at the component, sub-system, and system level. The results include estimates of uncertainty, and can predict reliability at some not-too-distant time in the future. This paper presents an overview of the underlying statistical model for the analysis, discusses model assumptions, and demonstrates usage of SRFYDO.

  14. Secure Reliable Processing Systems

    DTIC Science & Technology

    1981-07-01

    UCLA-ENG-7854), August 1978. Popek, G.J. and D.A. Farber. "A Model for Verification of Data Security in Operating Systems," Communications of the ACM...via covert channels is a data security problem. On the other hand, the unauthorized use of the system to communicate is a confinement problem. The...point here is that if there exists a communication channel, it may be accidentally used by a user and information leaked. For a system to be data secure

  15. Highly reliable PLC systems

    SciTech Connect

    Beckman, L.V.

    1995-03-01

    Today`s control engineers are afforded many options when designing microprocessor based systems for safety applications. The use of some form of redundancy is typical, but the final selection must match the requirements of the application. Should the system be fail safe or fault tolerant? Is safety the overriding consideration, or is production a concern as well? Are redundant PLC`s (Programmable Logic Controllers) adequate, or should a system specifically designed for safety applications be utilized? There is a considerable effort in progress, both in the USA and in Europe, to establish guidelines and standards which match the safety integrity of the system with the degree of risk inherent in the application. This paper is intended to provide an introduction to the subject, and explore some of the microprocessor based alternatives available to the control or safety engineer.

  16. Reliable inverter systems

    NASA Technical Reports Server (NTRS)

    Nagano, S.

    1979-01-01

    Base driver with common-load-current feedback protects paralleled inverter systems from open or short circuits. Circuit eliminates total system oscillation that can occur in conventional inverters because of open circuit in primary transformer winding. Common feedback signal produced by functioning modules forces operating frequency of failed module to coincide with clock drive so module resumes normal operating frequency in spite of open circuit.

  17. Secure Reliable Processing Systems

    DTIC Science & Technology

    1984-02-21

    specification successfully executed by application processes, technique draws from both the techniques of abstract data 121 Communications February 1980 of...J. and Farber. David A. "A \\lod’l for Verification of Data Security in Operating Systems." Communications of the ACM. Vol.21. No.9. September 1978. pp...the data being communicated exists in dleanext form as it is passed from one encrypted link to the next by the switch. Therefore the software in the

  18. Photovoltaic power system reliability considerations

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.

    1980-01-01

    An example of how modern engineering and safety techniques can be used to assure the reliable and safe operation of photovoltaic power systems is presented. This particular application is for a solar cell power system demonstration project designed to provide electric power requirements for remote villages. The techniques utilized involve a definition of the power system natural and operating environment, use of design criteria and analysis techniques, an awareness of potential problems via the inherent reliability and FMEA methods, and use of fail-safe and planned spare parts engineering philosophy.

  19. Designing magnetic systems for reliability

    SciTech Connect

    Heitzenroeder, P.J.

    1991-01-01

    Designing magnetic system is an iterative process in which the requirements are set, a design is developed, materials and manufacturing processes are defined, interrelationships with the various elements of the system are established, engineering analyses are performed, and fault modes and effects are studied. Reliability requires that all elements of the design process, from the seemingly most straightforward such as utilities connection design and implementation, to the most sophisticated such as advanced finite element analyses, receives a balanced and appropriate level of attention. D.B. Montgomery's study of magnet failures has shown that the predominance of magnet failures tend not to be in the most intensively engineered areas, but are associated with insulation, leads, ad unanticipated conditions. TFTR, JET, JT-60, and PBX are all major tokamaks which have suffered loss of reliability due to water leaks. Similarly the majority of causes of loss of magnet reliability at PPPL has not been in the sophisticated areas of the design but are due to difficulties associated with coolant connections, bus connections, and external structural connections. Looking towards the future, the major next-devices such as BPX and ITER are most costly and complex than any of their predecessors and are pressing the bounds of operating levels, materials, and fabrication. Emphasis on reliability is a must as the fusion program enters a phase where there are fewer, but very costly devices with the goal of reaching a reactor prototype stage in the next two or three decades. This paper reviews some of the magnet reliability issues which PPPL has faced over the years the lessons learned from them, and magnet design and fabrication practices which have been found to contribute to magnet reliability.

  20. Incorporation of Markov reliability models for digital instrumentation and control systems into existing PRAs

    SciTech Connect

    Bucci, P.; Mangan, L. A.; Kirschenbaum, J.; Mandelli, D.; Aldemir, T.; Arndt, S. A.

    2006-07-01

    Markov models have the ability to capture the statistical dependence between failure events that can arise in the presence of complex dynamic interactions between components of digital instrumentation and control systems. One obstacle to the use of such models in an existing probabilistic risk assessment (PRA) is that most of the currently available PRA software is based on the static event-tree/fault-tree methodology which often cannot represent such interactions. We present an approach to the integration of Markov reliability models into existing PRAs by describing the Markov model of a digital steam generator feedwater level control system, how dynamic event trees (DETs) can be generated from the model, and how the DETs can be incorporated into an existing PRA with the SAPHIRE software. (authors)

  1. Bioantioxidants: the systems reliability standpoint.

    PubMed

    Koltover, V K

    2009-01-01

    The antioxidant power of the so-called antioxidants is negligible because their rate constants and concentrations are too small to compete with the specialized defense enzymes, like superoxide dismutase (SOD), for the reactive oxygen species. In this short review, we present a number of experimental data of our group, along with the relevant literature data, to show that in-vivo antioxidants increase the systems reliability in other tacks. For example, butylated hydroxytoluene can prevent production of O2*- in mitochondria, whereas flavonoids can induce expression of antioxidant enzymes, SOD and catalase. We suggest that the timely introduction of antioxidants can provide the beneficial physiological effects through the prophylactic reliability maintenance against reactive forms of oxygen via the hormonal system.

  2. 49 CFR 230.57 - Injectors and feedwater pumps.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 4 2013-10-01 2013-10-01 false Injectors and feedwater pumps. 230.57 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a)...

  3. 49 CFR 230.57 - Injectors and feedwater pumps.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 4 2014-10-01 2014-10-01 false Injectors and feedwater pumps. 230.57 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a)...

  4. 49 CFR 230.57 - Injectors and feedwater pumps.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 4 2011-10-01 2011-10-01 false Injectors and feedwater pumps. 230.57 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a)...

  5. 49 CFR 230.57 - Injectors and feedwater pumps.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Injectors and feedwater pumps. 230.57 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a)...

  6. 49 CFR 230.57 - Injectors and feedwater pumps.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 4 2012-10-01 2012-10-01 false Injectors and feedwater pumps. 230.57 Section 230... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION STEAM LOCOMOTIVE INSPECTION AND MAINTENANCE STANDARDS Boilers and Appurtenances Injectors, Feedwater Pumps, and Flue Plugs § 230.57 Injectors and feedwater pumps. (a)...

  7. Performance testing of feedwater pump turbines

    SciTech Connect

    Finck, E.J.

    1980-01-01

    Utilities acknowledge that steam turbine drives for feedwater pumps outperform motor drives in improving station heat rate. Rising fuel prices frequently make steam costs the determining factor in evaluating feedwater pump drive turbines. Decisions made on efficiency differences as small as 0.2 percent often necessitate accurate performance testing to verify quoted efficiencies, making it imperative that accurate tests of turbine throttle flow, shaft speed and torque, and other parameters be run to ensure meaningful results. A highly specialized feed pump turbine manufacturers test facility is the most accurate testing method as well as the most convenient and potentially the most economical. 4 figures.

  8. 76 FR 16277 - System Restoration Reliability Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... Energy Regulatory Commission 18 CFR Part 40 System Restoration Reliability Standards AGENCY: Federal... Act, the Commission approves three Emergency Operations and Preparedness (EOP) Reliability Standards... Resource'' submitted to the Commission for approval by the North American Electric Reliability...

  9. 75 FR 71625 - System Restoration Reliability Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-24

    ... Energy Regulatory Commission 18 CFR Part 40 System Restoration Reliability Standards November 18, 2010... to approve Reliability Standards EOP-001-1 (Emergency Operations Planning), EOP- 005-2 (System... Commission by the North American Electric Reliability Corporation, the Electric Reliability Organization...

  10. Evaluation of examination techniques for ferritic stainless steel feedwater heater tubing

    SciTech Connect

    Nugent, M.J.; Catapano, M.C.

    1995-12-01

    Ferritic stainless steel has been finding increased application in utility plant feedwater heaters due to good strength and corrosion resistance and absence of potential copper contamination of feedwater system. Ferritic stainless steel is highly magnetic and is generally not inspectable using conventional eddy current testing techniques. A variety of techniques have been developed for inspection of this tubing material used in typical heat exchanger applications. Through a project funded by the Empire State Electric Energy Research Corporation (ESEERCO), the evaluation of data generated by four present state of the art NDE testing techniques were evaluated on a controlled mock-up of the heater tubing with service related defects. The primary objective was to determine the strengths and limitations of each method. The testing of two in service feedwater heaters at the Consolidated Edison Company of New York, Inc. (Con Edison`s) Arthur Kill Generating Station also allowed further evaluations based on actual field conditions.

  11. Evaluation of NDE techniques for type 439 stainless steel feedwater heater tubing

    SciTech Connect

    Nugent, M.J.; Catapano, M.C.

    1995-12-31

    Ferritic stainless steel has been finding increased application in utility plant feedwater heaters due to good strength and corrosion resistance and absence of potential copper contamination of feedwater system. Ferritic stainless steel is highly magnetic and is generally not inspectable using conventional eddy current testing techniques. A variety of techniques have been developed for inspection of this tubing material used in typical heat exchanger applications. Through a project completely funded by the Empire State Electric Energy Research Corporation (ESEERCO), the data generated by four present state of the art NDE testing techniques was evaluated on a controlled mock-up of the heater tubing with service related defects. The primary objective was to determine the strengths and limitations of each method. The testing of two (2) in service feedwater heaters at the Consolidated Edison Company of New York, Inc. (Con Edison`s) Arthur Kill Generating Station also allowed further evaluations based on actual field conditions.

  12. Reliability prediction for a class of highly reliable digital systems

    NASA Technical Reports Server (NTRS)

    White, Allan L.

    1992-01-01

    Three theorems which show that the reliability of a popular class of systems can be computed using small and simple models are presented. This class consists of systems that are assemblages of subsystems where each subsystem is a majority-voting threeplex plus spares or majority-voting fourplex plus spares. The theorems are error bounds for model reduction and simplification. The error bounds are given in terms of readily available system parameters. The three theorems have been applied to a system that has been used as an example that generates extremely large reliability models; the system considered is one version of AIPS (Advanced Information Processing System) for IAPSA (Integrated Airframe Propulsion System Architecture).

  13. Reliability prediction for a class of highly reliable digital systems

    NASA Astrophysics Data System (ADS)

    White, Allan L.

    Three theorems which show that the reliability of a popular class of systems can be computed using small and simple models are presented. This class consists of systems that are assemblages of subsystems where each subsystem is a majority-voting threeplex plus spares or majority-voting fourplex plus spares. The theorems are error bounds for model reduction and simplification. The error bounds are given in terms of readily available system parameters. The three theorems have been applied to a system that has been used as an example that generates extremely large reliability models; the system considered is one version of AIPS (Advanced Information Processing System) for IAPSA (Integrated Airframe Propulsion System Architecture).

  14. Multi-Agent System for Resource Reliability

    DTIC Science & Technology

    2007-11-02

    1 research and development of a prototype for network resource reliability has laid the groundwork for the Phase 2 implementation of MASRR, a Multi - Agent System for Resource Reliability, and its eventual commercialization.

  15. Electric system restructuring and system reliability

    NASA Astrophysics Data System (ADS)

    Horiuchi, Catherine Miller

    In 1996 the California legislature passed AB 1890, explicitly defining economic benefits and detailing specific mechanisms for initiating a partial restructuring the state's electric system. Critics have since sought re-regulation and proponents have asked for patience as the new institutions and markets take shape. Other states' electric system restructuring activities have been tempered by real and perceived problems in the California model. This study examines the reduced regulatory controls and new constraints introduced in California's limited restructuring model using utility and regulatory agency records from the 1990's to investigate effects of new institutions and practices on system reliability for the state's five largest public and private utilities. Logit and negative binomial regressions indicate negative impact from the California model of restructuring on system reliability as measured by customer interruptions. Time series analysis of outage data could not predict the wholesale power market collapse and the subsequent rolling blackouts in early 2001; inclusion of near-outage reliability disturbances---load shedding and energy emergencies---provided a measure of forewarning. Analysis of system disruptions, generation capacity and demand, and the role of purchased power challenge conventional wisdom on the causality of Californian's power problems. The quantitative analysis was supplemented by a targeted survey of electric system restructuring participants. Findings suggest each utility and the organization controlling the state's electric grid provided protection from power outages comparable to pre-restructuring operations through 2000; however, this reliability has come at an inflated cost, resulting in reduced system purchases and decreased marginal protection. The historic margin of operating safety has fully eroded, increasing mandatory load shedding and emergency declarations for voluntary and mandatory conservation. Proposed remedies focused

  16. PV Systems Reliability Final Technical Report.

    SciTech Connect

    Lavrova, Olga; Flicker, Jack David; Johnson, Jay; Armijo, Kenneth Miguel; Gonzalez, Sigifredo; Schindelholz, Eric John; Sorensen, Neil R.; Yang, Benjamin Bing-Yeh

    2015-12-01

    The continued exponential growth of photovoltaic technologies paves a path to a solar-powered world, but requires continued progress toward low-cost, high-reliability, high-performance photovoltaic (PV) systems. High reliability is an essential element in achieving low-cost solar electricity by reducing operation and maintenance (O&M) costs and extending system lifetime and availability, but these attributes are difficult to verify at the time of installation. Utilities, financiers, homeowners, and planners are demanding this information in order to evaluate their financial risk as a prerequisite to large investments. Reliability research and development (R&D) is needed to build market confidence by improving product reliability and by improving predictions of system availability, O&M cost, and lifetime. This project is focused on understanding, predicting, and improving the reliability of PV systems. The two areas being pursued include PV arc-fault and ground fault issues, and inverter reliability.

  17. Reliability of Naval Radar Systems

    DTIC Science & Technology

    1978-09-01

    the driver uses as much prime power to produce a few watts as the output tube does to produce several kilo- watts. Large klystrons , such as the ones...ITEMS: transmitter ANTENNA SITE: 214 diam (7’) power resistors, sero amplifiers, ANTENNA GAIN (d): 41 encoder, klystron (4) POLARIZATION: horizontal...whM.ch will be developed are the differences in mission, power levels, stress, and costs allowed for the development and assurance of reliability. (U

  18. Reliability Growth in Space Life Support Systems

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.

    2014-01-01

    A hardware system's failure rate often increases over time due to wear and aging, but not always. Some systems instead show reliability growth, a decreasing failure rate with time, due to effective failure analysis and remedial hardware upgrades. Reliability grows when failure causes are removed by improved design. A mathematical reliability growth model allows the reliability growth rate to be computed from the failure data. The space shuttle was extensively maintained, refurbished, and upgraded after each flight and it experienced significant reliability growth during its operational life. In contrast, the International Space Station (ISS) is much more difficult to maintain and upgrade and its failure rate has been constant over time. The ISS Carbon Dioxide Removal Assembly (CDRA) reliability has slightly decreased. Failures on ISS and with the ISS CDRA continue to be a challenge.

  19. Reliability Assessment of SMART Reactor Protection System

    SciTech Connect

    Won Young, Yun; Choong Heui, Jeong; Seong Hun, Kim; Sang Yong, Lee

    2006-07-01

    Component failure rates and integrated system reliability of the SMART reactor protection system were analyzed. The analysis tool of the study was the RELEX 7 computer program developed by Relex Software Corporation. The RELEX software is a PC based computer program which includes the part stress analysis models and the RBD analysis model to calculate component and system reliability. The component failure rate data for the study was selected from the MIL-HDBK-217F. (authors)

  20. Production Facility System Reliability Analysis Report

    SciTech Connect

    Dale, Crystal Buchanan; Klein, Steven Karl

    2015-10-06

    This document describes the reliability, maintainability, and availability (RMA) modeling of the Los Alamos National Laboratory (LANL) design for the Closed Loop Helium Cooling System (CLHCS) planned for the NorthStar accelerator-based 99Mo production facility. The current analysis incorporates a conceptual helium recovery system, beam diagnostics, and prototype control system into the reliability analysis. The results from the 1000 hr blower test are addressed.

  1. B-52 stability augmentation system reliability

    NASA Technical Reports Server (NTRS)

    Bowling, T. C.; Key, L. W.

    1976-01-01

    The B-52 SAS (Stability Augmentation System) was developed and retrofitted to nearly 300 aircraft. It actively controls B-52 structural bending, provides improved yaw and pitch damping through sensors and electronic control channels, and puts complete reliance on hydraulic control power for rudder and elevators. The system has experienced over 300,000 flight hours and has exhibited service reliability comparable to the results of the reliability test program. Development experience points out numerous lessons with potential application in the mechanization and development of advanced technology control systems of high reliability.

  2. Multi-Disciplinary System Reliability Analysis

    NASA Technical Reports Server (NTRS)

    Mahadevan, Sankaran; Han, Song

    1997-01-01

    The objective of this study is to develop a new methodology for estimating the reliability of engineering systems that encompass multiple disciplines. The methodology is formulated in the context of the NESSUS probabilistic structural analysis code developed under the leadership of NASA Lewis Research Center. The NESSUS code has been successfully applied to the reliability estimation of a variety of structural engineering systems. This study examines whether the features of NESSUS could be used to investigate the reliability of systems in other disciplines such as heat transfer, fluid mechanics, electrical circuits etc., without considerable programming effort specific to each discipline. In this study, the mechanical equivalence between system behavior models in different disciplines are investigated to achieve this objective. A new methodology is presented for the analysis of heat transfer, fluid flow, and electrical circuit problems using the structural analysis routines within NESSUS, by utilizing the equivalence between the computational quantities in different disciplines. This technique is integrated with the fast probability integration and system reliability techniques within the NESSUS code, to successfully compute the system reliability of multi-disciplinary systems. Traditional as well as progressive failure analysis methods for system reliability estimation are demonstrated, through a numerical example of a heat exchanger system involving failure modes in structural, heat transfer and fluid flow disciplines.

  3. Reliability Results of NERSC Systems

    SciTech Connect

    Petascale Data Storage Institute; Mokhtarani, Akbar; Mokhtarani, Akbar; Kramer, William; Hick, Jason

    2008-05-27

    In order to address the needs of future scientific applications for storing and accessing large amounts of data in an efficient way, one needs to understand the limitations of current technologies and how they may cause systeminstability or unavailability. A number of factors can impact system availability ranging from facility-wide power outage to a single point of failure such as network switches or global file systems. In addition, individual component failure in a system can degrade the performance of that system. This paper focuses on analyzing both of these factors and their impacts on the computational and storage systems at NERSC. Component failure data presented in this report primarily focuses on disk drive in on of the computational system and tape drive failure in HPSS. NERSC collected available component failure data and system-wide outages for its computational and storage systems over a six-year period and made them available to the HPC community through the Petascale Data Storage Institute.

  4. Operational reliability of standby safety systems

    SciTech Connect

    Grant, G.M.; Atwood, C.L.; Gentillon, C.D.

    1995-04-01

    The Idaho National Engineering Laboratory (INEL) is evaluating the operational reliability of several risk-significant standby safety systems based on the operating experience at US commercial nuclear power plants from 1987 through 1993. The reliability assessed is the probability that the system will perform its Probabilistic Risk Assessment (PRA) defined safety function. The quantitative estimates of system reliability are expected to be useful in risk-based regulation. This paper is an overview of the analysis methods and the results of the high pressure coolant injection (HPCI) system reliability study. Key characteristics include (1) descriptions of the data collection and analysis methods, (2) the statistical methods employed to estimate operational unreliability, (3) a description of how the operational unreliability estimates were compared with typical PRA results, both overall and for each dominant failure mode, and (4) a summary of results of the study.

  5. Reliability improvement of distribution systems using SSVR.

    PubMed

    Hosseini, Mehdi; Shayanfar, Heidar Ali; Fotuhi-Firuzabad, Mahmoud

    2009-01-01

    This paper presents a reliability assessment algorithm for distribution systems using a Static Series Voltage Regulator (SSVR). Furthermore, this algorithm considers the effects of Distributed Generation (DG) units, alternative sources, system reconfiguration, load shedding and load adding on distribution system reliability indices. In this algorithm, load points are classified into 8 types and separated restoration times are considered for each class. Comparative studies are conducted to investigate the impacts of DG and alternative source unavailability on the distribution system reliability. For reliability assessment, the customer-oriented reliability indices such as SAIFI, SAIDI, CAIDI ASUI and also load- and energy-oriented indices such as ENS and AENS are evaluated. The effectiveness of the proposed algorithm is examined on the two standard distribution systems consisting of 33 and 69 nodes. The best location of the SSVR in distribution systems is determined based on different reliability indices, separately. Results show that the proposed algorithm is efficient for large-scale radial distribution systems and can accommodate the effects of fault isolation and load restoration.

  6. a Reliability Evaluation System of Association Rules

    NASA Astrophysics Data System (ADS)

    Chen, Jiangping; Feng, Wanshu; Luo, Minghai

    2016-06-01

    In mining association rules, the evaluation of the rules is a highly important work because it directly affects the usability and applicability of the output results of mining. In this paper, the concept of reliability was imported into the association rule evaluation. The reliability of association rules was defined as the accordance degree that reflects the rules of the mining data set. Such degree contains three levels of measurement, namely, accuracy, completeness, and consistency of rules. To show its effectiveness, the "accuracy-completeness-consistency" reliability evaluation system was applied to two extremely different data sets, namely, a basket simulation data set and a multi-source lightning data fusion. Results show that the reliability evaluation system works well in both simulation data set and the actual problem. The three-dimensional reliability evaluation can effectively detect the useless rules to be screened out and add the missing rules thereby improving the reliability of mining results. Furthermore, the proposed reliability evaluation system is applicable to many research fields; using the system in the analysis can facilitate obtainment of more accurate, complete, and consistent association rules.

  7. Demand Response For Power System Reliability: FAQ

    SciTech Connect

    Kirby, Brendan J

    2006-12-01

    Demand response is the most underutilized power system reliability resource in North America. Technological advances now make it possible to tap this resource to both reduce costs and improve. Misconceptions concerning response capabilities tend to force loads to provide responses that they are less able to provide and often prohibit them from providing the most valuable reliability services. Fortunately this is beginning to change with some ISOs making more extensive use of load response. This report is structured as a series of short questions and answers that address load response capabilities and power system reliability needs. Its objective is to further the use of responsive load as a bulk power system reliability resource in providing the fastest and most valuable ancillary services.

  8. Reliability of photovoltaic systems: A field report

    NASA Astrophysics Data System (ADS)

    Thomas, M. G.; Fuentes, M. K.; Lashway, C.; Black, B. D.

    Performance studies and field measurements of photovoltaic systems indicate a 1 to 2% per year degradation in array energy production. The cause for much of the degradation has been identified as soiling, failed modules, and failures in interconnections. System performance evaluation continues to be complicated by the poor reliability of some power conditioning hardware that has greatly diminished the system availability and by inconsistent field ratings. Nevertheless, the current system reliability is consistent with degradation of less than 10% in 5 years and with estimates of less than 10% per year of the energy value for O and M.

  9. Reliability of photovoltaic systems - A field report

    NASA Astrophysics Data System (ADS)

    Thomas, M. G.; Fuentes, M. K.; Lashway, C.; Black, B. D.

    Performance studies and field measurements of photovoltaic systems indicate a 1-2-percent/yr degradation in array energy production. The cause for much of the degradation has been identified as soiling, failed modules, and failures in interconnections. System performance evaluation continues to be complicated by the poor reliability of some power conditioning hardware (which greatly diminished system availability) and by inconsistent field ratings. Nevertheless, the current system reliability is consistent with degradation of less than 10 percent in 5 years and with estimates of less than 10 percent/yr of the energy value for O&M.

  10. System Reliability for LED-Based Products

    SciTech Connect

    Davis, J Lynn; Mills, Karmann; Lamvik, Michael; Yaga, Robert; Shepherd, Sarah D; Bittle, James; Baldasaro, Nick; Solano, Eric; Bobashev, Georgiy; Johnson, Cortina; Evans, Amy

    2014-04-07

    Results from accelerated life tests (ALT) on mass-produced commercially available 6” downlights are reported along with results from commercial LEDs. The luminaires capture many of the design features found in modern luminaires. In general, a systems perspective is required to understand the reliability of these devices since LED failure is rare. In contrast, components such as drivers, lenses, and reflector are more likely to impact luminaire reliability than LEDs.

  11. Looking south at boiler feedwater pumps (steam turbine pump on ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking south at boiler feedwater pumps (steam turbine pump on left, electric motor pump on right). - Wheeling-Pittsburgh Steel Corporation, Allenport Works, Boiler House, Route 88 on West bank of Monongahela River, Allenport, Washington County, PA

  12. 29. NORTHWEST VIEW OF BOILER FEEDWATER CHEMICAL REACTION TANKS, WITH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    29. NORTHWEST VIEW OF BOILER FEEDWATER CHEMICAL REACTION TANKS, WITH FORMER GENERAL OFFICE BUILDING IN BACKGROUND. - U.S. Steel Duquesne Works, Fuel & Utilities Plant, Along Monongahela River, Duquesne, Allegheny County, PA

  13. Corrosion-related failures in feedwater heaters. Final report

    SciTech Connect

    Beavers, J.A.; Agrawal, A.K.; Berry, W.E.

    1983-07-01

    A survey of the literature was performed for the Electric Power Research Institute on corrosion-related failures in feedwater heaters. The survey was directed toward failures in fossil and in pressurized water reactor (PWR) nuclear power plants, but includes some pertinent information related to failures in boiling water reactor (BWR) power plants. The survey was organized into sections on the commonly used feedwater heater materials; C steel, brasses, Cu-Ni alloys, MONEL Alloy 400, and Type 304 Stainless Steel. A section on Ti as a potential feedwater heater material also is given in the appendices. Each section is divided into subsections on field experience and laboratory studies tat relate to the field failures that have been observed. Appendices are given on a feedwater heater description, water quality in power plants, forms of corrosion, and failure analysis techniques.

  14. Detail view of feedwater pump (below) and preheater tanks (above) ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Detail view of feedwater pump (below) and preheater tanks (above) in boiler house. - Burnsville Natural Gas Pumping Station, Saratoga Avenue between Little Kanawha River & C&O Railroad line, Burnsville, Braxton County, WV

  15. Looking south at a chemical mixing tank for boiler feedwater. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Looking south at a chemical mixing tank for boiler feedwater. - Wheeling-Pittsburgh Steel Corporation, Allenport Works, Boiler House, Route 88 on West bank of Monongahela River, Allenport, Washington County, PA

  16. Large-scale systems: Complexity, stability, reliability

    NASA Technical Reports Server (NTRS)

    Siljak, D. D.

    1975-01-01

    After showing that a complex dynamic system with a competitive structure has highly reliable stability, a class of noncompetitive dynamic systems for which competitive models can be constructed is defined. It is shown that such a construction is possible in the context of the hierarchic stability analysis. The scheme is based on the comparison principle and vector Liapunov functions.

  17. System reliability analysis through corona testing

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Mueller, L. A.; Koutnik, E. A.

    1975-01-01

    In the Reliability and Quality Engineering Test Laboratory at the NASA Lewis Research Center a nondestructive, corona-vacuum test facility for testing power system components was developed using commercially available hardware. The test facility was developed to simulate operating temperature and vacuum while monitoring corona discharges with residual gases. This facility is being used to test various high voltage power system components.

  18. System reliability analysis through corona testing

    NASA Technical Reports Server (NTRS)

    Lalli, V. R.; Mueller, L. A.; Koutnik, E. A.

    1975-01-01

    A corona vacuum test facility for nondestructive testing of power system components was built in the Reliability and Quality Engineering Test Laboratories at the NASA Lewis Research Center. The facility was developed to simulate operating temperature and vacuum while monitoring corona discharges with residual gases. The facility is being used to test various high-voltage power system components.

  19. Theory of reliable systems. [reliability analysis and on-line fault diagnosis

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.

    1974-01-01

    Research is reported in the program to refine the current notion of system reliability by identifying and investigating attributes of a system which are important to reliability considerations, and to develop techniques which facilitate analysis of system reliability. Reliability analysis, and on-line fault diagnosis are discussed.

  20. Theory of reliable systems. [systems analysis and design

    NASA Technical Reports Server (NTRS)

    Meyer, J. F.

    1973-01-01

    The analysis and design of reliable systems are discussed. The attributes of system reliability studied are fault tolerance, diagnosability, and reconfigurability. Objectives of the study include: to determine properties of system structure that are conducive to a particular attribute; to determine methods for obtaining reliable realizations of a given system; and to determine how properties of system behavior relate to the complexity of fault tolerant realizations. A list of 34 references is included.

  1. Plant data comparisons for Comanche Peak 1/2 main feedwater pump trip transient

    SciTech Connect

    Boatwright, W.J.; Choe, W.G; Hiltbrand, D.W.

    1995-09-01

    A RETRAN-02 MOD5 model of Comanche Peak Steam Electric Station was developed by TU Electric for the purpose of performing core reload safety analyses. In order to qualify this model, comparisons against plant transient data from a partial loss of main feedwater flow were performed. These comparisons demonstrated that good representations of the plant response could be obtained with RETRAN-02 and the user-developed models of the primary-to-secondary heat transfer and plant control systems.

  2. Loss-of-normal-feedwater sensitivity studies for AP600 behavior characterization

    SciTech Connect

    Saiu, G.; Del Nero, G.; Madonna, A.; Marella, G.; Orazi, A.

    1996-09-01

    Activity concerning the development of a RELAP5/MOD3 model to simulate the Westinghouse Electric Corporation AP600 is summarized. The aim is to gain initial insight into the capability of RELAP5 to simulate the behavior of AP600 safety features. A-loss-of-normal-feedwater event is studied. Of the transients that must be investigated, this transient has been chosen to be one of the most relevant because the response of the AP600 to a loss-of-normal-feedwater event differs significantly from that of current pressurized water reactors in the extensive use of passive safety features peculiar to the AP600. Also, strong interactions among the AP600 safety systems, which should be further analyzed to permit full optimization of the system actuation logic and operation, are shown. Finally, a loss of normal feedwater without reactor scram, performed to investigate short-term plant behavior, shows that the pressure peak is affected by critical discharge flow coefficients applied to the pressurizer safety valves, while a relatively small reduction of the pressure peak is observed when both heat exchangers of the passive heat removal system are operating as opposed to the case in which only one is available. The data used for this study are derived from the Standard Safety Analysis Report configuration of the Westinghouse AP600 as of 1992.

  3. Structural system reliability under multiple failure modes

    NASA Technical Reports Server (NTRS)

    Mahadevan, S.; Chamis, C. C.

    1993-01-01

    This paper describes a computational method for system reliability estimation of propulsion structures. The failure domain of the entire structural system is computed through the union of failure regions for various critical system failure modes. The effect of non-critical progressive damage is incorporated through structural reanalysis, resulting in the construction of several linear segments to approximately cover the system failure domain. An adaptive damage imposition scheme is outlined for the sake of computational efficiency. The proposed method is used to construct the system survival cdf (cumulative distribution function) of a two-rotor system.

  4. Long life reliability thermal control systems study

    NASA Technical Reports Server (NTRS)

    Scollon, T. R., Jr.; Killen, R. E.

    1972-01-01

    The results of a program undertaken to conceptually design and evaluate a passive, high reliability, long life thermal control system for space station application are presented. The program consisted of four steps: (1) investigate and select potential thermal system elements; (2) conceive, evaluate and select a thermal control system using these elements; (3) conduct a verification test of a prototype segment of the selected system; and (4) evaluate the utilization of waste heat from the power supply. The result of this project is a conceptual thermal control system design which employs heat pipes as primary components, both for heat transport and temperature control. The system, its evaluation, and the test results are described.

  5. Sustainable, Reliable Mission-Systems Architecture

    NASA Technical Reports Server (NTRS)

    O'Neil, Graham; Orr, James K.; Watson, Steve

    2007-01-01

    A mission-systems architecture, based on a highly modular infrastructure utilizing: open-standards hardware and software interfaces as the enabling technology is essential for affordable and sustainable space exploration programs. This mission-systems architecture requires (a) robust communication between heterogeneous system, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, and verification of systems, and (e) minimal sustaining engineering. This paper proposes such an architecture. Lessons learned from the Space Shuttle program and Earthbound complex engineered system are applied to define the model. Technology projections reaching out 5 years are mde to refine model details.

  6. Sustainable, Reliable Mission-Systems Architecture

    NASA Technical Reports Server (NTRS)

    O'Neil, Graham; Orr, James K.; Watson, Steve

    2005-01-01

    A mission-systems architecture, based on a highly modular infrastructure utilizing open-standards hardware and software interfaces as the enabling technology is essential for affordable md sustainable space exploration programs. This mission-systems architecture requires (8) robust communication between heterogeneous systems, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, end verification of systems, and (e) minimal sustaining engineering. This paper proposes such an architecture. Lessons learned from the Space Shuttle program and Earthbound complex engineered systems are applied to define the model. Technology projections reaching out 5 years are made to refine model details.

  7. System-Reliability Cumulative-Binomial Program

    NASA Technical Reports Server (NTRS)

    Scheuer, Ernest M.; Bowerman, Paul N.

    1989-01-01

    Cumulative-binomial computer program, NEWTONP, one of set of three programs, calculates cumulative binomial probability distributions for arbitrary inputs. NEWTONP, CUMBIN (NPO-17555), and CROSSER (NPO-17557), used independently of one another. Program finds probability required to yield given system reliability. Used by statisticians and users of statistical procedures, test planners, designers, and numerical analysts. Program written in C.

  8. Reliability achievement in high technology space systems

    NASA Technical Reports Server (NTRS)

    Lindstrom, D. L.

    1981-01-01

    The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

  9. Aging assessment of auxiliary feedwater pumps

    SciTech Connect

    Greenstreet, W.L.

    1987-01-01

    ORNL is conducting aging assessments of auxiliary feedwater pumps to provide recommendations for monitoring and assessing the severity of time-dependent degradation as well as to recommend maintenance and replacement practices. Cornerstones of these activities are the identification of failure modes and causes and ranking of causes. Failure modes and causes of interest are those due to aging and service wear. Design details, functional requirements, and operating experience data were used to identify failure modes and causes and to rank the latter. Based on this input, potentially useful inspection, surveillance, and condition monitoring methods that are currently available for use or in the developmental stage were examined and recommendations made. The methods selected are listed and discussed in terms of use and information to be obtained. Relationships between inspection, surveillance, and monitoring and maintenance practices entered prominently into maintenance recommendations. These recommendations, therefore, embrace predictive as well as corrective and preventative maintenance practices. The recommendations are described, inspection details are discussed, and periodic inspection and maintenance interval guidelines are given. Surveillance testing at low-flow conditions is also discussed. It is shown that this type of testing can lead to accelerated aging.

  10. A second look at launch system reliability

    NASA Astrophysics Data System (ADS)

    Fragola, Joseph R.

    1991-11-01

    For designers involved in the Advanced Launch Development Program, perspective must shift from mere performance toward 'total quality' in order to obtain unprecedented in-service reliability. Total quality involves balancing performance with ease of manufacture and ease of testing from the outset of conceptual design development. Design, manufacturing, assembly, and reliability engineering tools must accordingly be applied concurrently, so that all engineering tasks are directed toward the elimination of defects; a technical performance measuring system (TPMS) provides overall management of this process. TPMS entails the use of probabilistic design analysis, which furnishes a risk-balanced set of design guidelines.

  11. Reliability Issues in Stirling Radioisotope Power Systems

    NASA Technical Reports Server (NTRS)

    Shah, Ashwin R.; Schreiber, Jeffrey G.

    2004-01-01

    Stirling power conversion is a potential candidate for use in a Radioisotope Power System (RPS) for space science missions because it offers a multifold increase in the conversion efficiency of heat to electric power and reduced requirement of radioactive material. Reliability of an RPS that utilizes Stirling power conversion technology is important in order to ascertain long term successful performance. Owing to long life time requirement (14 years), it is difficult to perform long-term tests that encompass all the uncertainties involved in the design variables of components and subsystems comprising the RPS. The requirement for uninterrupted performance reliability and related issues are discussed, and some of the critical areas of concern are identified. An overview of the current on-going efforts to understand component life, design variables at the component and system levels, and related sources and nature of uncertainties are also discussed. Current status of the 110 watt Stirling Radioisotope Generator (SRG110) reliability efforts is described. Additionally, an approach showing the use of past experience on other successfully used power systems to develop a reliability plan for the SRG110 design is outlined.

  12. Making programmable BMS safe and reliable

    SciTech Connect

    Cusimano, J.A.

    1995-12-01

    Burner management systems ensure safe admission of fuel to the furnace and prevent explosions. This article describes how programmable control systems can be every bit as safe and reliable as hardwired or standard programmable logic controller-based designs. High-pressure boilers are required by regulatory agencies and insurance companies alike to be equipped with a burner management system (BMS) to ensure safe admission of fuel to the furnace and to prevent explosions. These systems work in parallel with, but independently of, the combustion and feedwater control systems that start up, monitor, and shut down burners and furnaces. Safety and reliability are the fundamental requirements of a BMS. Programmable control system for BMS applications are now available that incorporate high safety and reliability into traditional microprocessor-based designs. With one of these control systems, a qualified systems engineer applying relevant standards, such as the National Fire Protection Assn (NFPA) 85 series, can design and implement a superior BMS.

  13. 76 FR 42534 - Mandatory Reliability Standards for Interconnection Reliability Operating Limits; System...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-19

    ... Reliability Operating Limits; System Restoration Reliability Standards AGENCY: Federal Energy Regulatory... necessary to analyze and monitor Interconnection Reliability Operating Limits (IROL) within its Wide-Area... Interconnection Reliability Operating Limits, Order No. 748, 134 FERC ] 61,213 (2011). \\2\\ The term...

  14. Reliability modelling for non-electronic systems

    NASA Astrophysics Data System (ADS)

    Valisena, N.; Demollerat, T.

    An approach for reliability modeling of nonelectronic systems is presented. The need for a specific methodology to be applied in the nonelectronic area is justified because nonelectronic items are generally single point failure of the system, and the classical approach used in electronics cannot be realistically applied to nonelectronic items, due to their particularities. Specific models, depending on both design margins and provisions for realization aspects, are proposed. Examples of such models and rules of combination of the models at system level are given. The results of research conducted on typical probabilities in the space area for human errors and inspection efficiencies are presented.

  15. Mass and Reliability System (MaRS)

    NASA Technical Reports Server (NTRS)

    Barnes, Sarah

    2016-01-01

    The Safety and Mission Assurance (S&MA) Directorate is responsible for mitigating risk, providing system safety, and lowering risk for space programs from ground to space. The S&MA is divided into 4 divisions: The Space Exploration Division (NC), the International Space Station Division (NE), the Safety & Test Operations Division (NS), and the Quality and Flight Equipment Division (NT). The interns, myself and Arun Aruljothi, will be working with the Risk & Reliability Analysis Branch under the NC Division's. The mission of this division is to identify, characterize, diminish, and communicate risk by implementing an efficient and effective assurance model. The team utilizes Reliability and Maintainability (R&M) and Probabilistic Risk Assessment (PRA) to ensure decisions concerning risks are informed, vehicles are safe and reliable, and program/project requirements are realistic and realized. This project pertains to the Orion mission, so it is geared toward a long duration Human Space Flight Program(s). For space missions, payload is a critical concept; balancing what hardware can be replaced by components verse by Orbital Replacement Units (ORU) or subassemblies is key. For this effort a database was created that combines mass and reliability data, called Mass and Reliability System or MaRS. The U.S. International Space Station (ISS) components are used as reference parts in the MaRS database. Using ISS components as a platform is beneficial because of the historical context and the environment similarities to a space flight mission. MaRS uses a combination of systems: International Space Station PART for failure data, Vehicle Master Database (VMDB) for ORU & components, Maintenance & Analysis Data Set (MADS) for operation hours and other pertinent data, & Hardware History Retrieval System (HHRS) for unit weights. MaRS is populated using a Visual Basic Application. Once populated, the excel spreadsheet is comprised of information on ISS components including

  16. 77 FR 7526 - Interpretation of Protection System Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-13

    ... Energy Regulatory Commission 18 CFR Part 40 Interpretation of Protection System Reliability Standard... North American Electric Reliability Corporation (NERC) submitted a petition (Petition) requesting approval of NERC's interpretation of Requirement R1 of Commission-approved Reliability Standard...

  17. Reliability assessment of nuclear structural systems

    SciTech Connect

    Reich, M.; Hwang, H.

    1983-01-01

    Reliability assessment of nuclear structural systems has been receiving more emphasis over the last few years. This paper deals with the recent progress made by the Structural Analysis Division of Brookhaven National Laboratory (BNL), in the development of a probability-based reliability analysis methodology for safety evaluation of reactor containments and other seismic category I structures. An important feature of this methodology is the incorporation of finite element analysis and random vibration theory. By utilizing this method, it is possible to evaluate the safety of nuclear structures under various static and dynamic loads in terms of limit state probability. Progress in other related areas, such as the establishment of probabilistic characteristics for various loads and structural resistance, are also described. Results of an application of the methodology to a realistic reinforced concrete containment subjected to dead and live loads, accidental internal pressures and earthquake ground accelerations are presented.

  18. System statistical reliability model and analysis

    NASA Technical Reports Server (NTRS)

    Lekach, V. S.; Rood, H.

    1973-01-01

    A digital computer code was developed to simulate the time-dependent behavior of the 5-kwe reactor thermoelectric system. The code was used to determine lifetime sensitivity coefficients for a number of system design parameters, such as thermoelectric module efficiency and degradation rate, radiator absorptivity and emissivity, fuel element barrier defect constant, beginning-of-life reactivity, etc. A probability distribution (mean and standard deviation) was estimated for each of these design parameters. Then, error analysis was used to obtain a probability distribution for the system lifetime (mean = 7.7 years, standard deviation = 1.1 years). From this, the probability that the system will achieve the design goal of 5 years lifetime is 0.993. This value represents an estimate of the degradation reliability of the system.

  19. Design philosophy for reliable systems, including control

    SciTech Connect

    Gabriel, J.R.

    1984-04-01

    In the past, use of computers and software to manage physical plant has usually involved systems similar to the clockwork automata of the 17th century. The next generation of plant control will include intelligent systems - computer systems having knowledge of the plant and being capable of intelligent behavior, even though only some control functions will need such expertise. This report develops a framework for a universe of discourse usable by such non-human experts. It is based on the idea that a design has many features of a contract and may be described as a contract between humans and a machine, defining what each must do to attain a goal. Several points are discussed: the use of techniques in analytical redundancy and their place as analogues in administrative control for conventional techniques in physical control; the use of redundant computer systems to protect against hardware faults; the necessity to prove properties of software used in redundant hardware, because software faults are common modes across redundant hardware; and some issues in choosing a programming language for provable control software. Because proof of correctness is costly, it should be used only where necessary. This report concludes that the degree of reliability needed by the plant model used in analytic redundancy protection need not be nearly as reliable as the mechanism to detect discrepancy between plant and model.

  20. A High Reliability Accelerator Control System

    NASA Astrophysics Data System (ADS)

    Callahan, John; Collins, John; Hunt, William; Qualls, Andrew

    1997-05-01

    This paper describes the control system developed at IUCF for the Cooler Injector Synchrotron (CIS). The Hardware system is VME based and employs fiber optic data transmission for high noise rejection. The hardware includes several modules designed and manufactured at IUCF to meet specifications not attainable with commercial hardware. These modules feature active redundancy with automatic switch over for high reliability; built in test and self diagnosis with centralized failure and system health monitoring for rapid maintenance; and very low drift and self calibration for maximum repeatability. We describe several modules including high precision ramping and non-ramping DAC/ADCs and a deep memory timing sequencer. We give a brief overview of the software system, which is based on Vsystem from Vista, Inc.

  1. Pump system characterization and reliability enhancement

    SciTech Connect

    Staunton, R.H.

    1997-09-01

    Pump characterization studies were performed at the Oak Ridge National Laboratory (ORNL) to review and analyze six years (1990 to 1995) of data from pump systems at domestic nuclear plants. The studies considered not only pumps and pump motors but also pump related circuit breakers and turbine drives (i.e., the pump system). One significant finding was that the number of significant failures of the pump circuit breaker exceeds the number of significant failures of the pump itself. The study also shows how regulatory code testing was designed for the pump only and therefore did not lead to the discovery of other significant pump system failures. Potential diagnostic technologies both experimental and mature, suitable for on-line and off-line pump testing were identified. The study does not select or recommend technologies but proposes diagnostic technologies and monitoring techniques that should be further evaluated/developed for making meaningful and critically needed improvements in the reliability of the pump system.

  2. SLAC modulator system improvements and reliability results

    SciTech Connect

    Donaldson, A.R.

    1998-06-01

    In 1995, an improvement project was completed on the 244 klystron modulators in the linear accelerator. The modulator system has been previously described. This article offers project details and their resulting effect on modulator and component reliability. Prior to the project, the authors had collected four operating cycles (1991 through 1995) of MTTF data. In this discussion, the '91 data will be excluded since the modulators operated at 60 Hz. The five periods following the '91 run were reviewed due to the common repetition rate at 120 Hz.

  3. Reliable Neuronal Systems: The Importance of Heterogeneity

    PubMed Central

    Lengler, Johannes; Jug, Florian; Steger, Angelika

    2013-01-01

    For every engineer it goes without saying: in order to build a reliable system we need components that consistently behave precisely as they should. It is also well known that neurons, the building blocks of brains, do not satisfy this constraint. Even neurons of the same type come with huge variances in their properties and these properties also vary over time. Synapses, the connections between neurons, are highly unreliable in forwarding signals. In this paper we argue that both these fact add variance to neuronal processes, and that this variance is not a handicap of neural systems, but that instead predictable and reliable functional behavior of neural systems depends crucially on this variability. In particular, we show that higher variance allows a recurrently connected neural population to react more sensitively to incoming signals, and processes them faster and more energy efficient. This, for example, challenges the general assumption that the intrinsic variability of neurons in the brain is a defect that has to be overcome by synaptic plasticity in the process of learning. PMID:24324621

  4. Reliability of dynamic systems under limited information.

    SciTech Connect

    Field, Richard V., Jr.; Grigoriu, Mircea

    2006-09-01

    A method is developed for reliability analysis of dynamic systems under limited information. The available information includes one or more samples of the system output; any known information on features of the output can be used if available. The method is based on the theory of non-Gaussian translation processes and is shown to be particularly suitable for problems of practical interest. For illustration, we apply the proposed method to a series of simple example problems and compare with results given by traditional statistical estimators in order to establish the accuracy of the method. It is demonstrated that the method delivers accurate results for the case of linear and nonlinear dynamic systems, and can be applied to analyze experimental data and/or mathematical model outputs. Two complex applications of direct interest to Sandia are also considered. First, we apply the proposed method to assess design reliability of a MEMS inertial switch. Second, we consider re-entry body (RB) component vibration response during normal re-entry, where the objective is to estimate the time-dependent probability of component failure. This last application is directly relevant to re-entry random vibration analysis at Sandia, and may provide insights on test-based and/or model-based qualification of weapon components for random vibration environments.

  5. Demand Response as a System Reliability Resource

    SciTech Connect

    Eto, Joseph H.; Lewis, Nancy Jo; Watson, David; Kiliccote, Sila; Auslander, David; Paprotny, Igor; Makarov, Yuri

    2012-12-31

    The Demand Response as a System Reliability Resource project consists of six technical tasks: • Task 2.1. Test Plan and Conduct Tests: Contingency Reserves Demand Response (DR) Demonstration—a pioneering demonstration of how existing utility load-management assets can provide an important electricity system reliability resource known as contingency reserve. • Task 2.2. Participation in Electric Power Research Institute (EPRI) IntelliGrid—technical assistance to the EPRI IntelliGrid team in developing use cases and other high-level requirements for the architecture. • Task 2.3. Research, Development, and Demonstration (RD&D) Planning for Demand Response Technology Development—technical support to the Public Interest Energy Research (PIER) Program on five topics: Sub-task 1. PIER Smart Grid RD&D Planning Document; Sub-task 2. System Dynamics of Programmable Controllable Thermostats; Sub-task 3. California Independent System Operator (California ISO) DR Use Cases; Sub-task 4. California ISO Telemetry Requirements; and Sub-task 5. Design of a Building Load Data Storage Platform. • Task 2.4. Time Value of Demand Response—research that will enable California ISO to take better account of the speed of the resources that it deploys to ensure compliance with reliability rules for frequency control. • Task 2.5. System Integration and Market Research: Southern California Edison (SCE)—research and technical support for efforts led by SCE to conduct demand response pilot demonstrations to provide a contingency reserve service (known as non-spinning reserve) through a targeted sub-population of aggregated residential and small commercial customers enrolled in SCE’s traditional air conditioning (AC) load cycling program, the Summer Discount Plan. • Task 2.6. Demonstrate Demand Response Technologies: Pacific Gas and Electric (PG&E)—research and technical support for efforts led by PG&E to conduct a demand response pilot demonstration to provide non

  6. Integrated Reliability and Risk Analysis System (IRRAS)

    SciTech Connect

    Russell, K D; McKay, M K; Sattison, M.B. Skinner, N.L.; Wood, S T; Rasmuson, D M

    1992-01-01

    The Integrated Reliability and Risk Analysis System (IRRAS) is a state-of-the-art, microcomputer-based probabilistic risk assessment (PRA) model development and analysis tool to address key nuclear plant safety issues. IRRAS is an integrated software tool that gives the user the ability to create and analyze fault trees and accident sequences using a microcomputer. This program provides functions that range from graphical fault tree construction to cut set generation and quantification. Version 1.0 of the IRRAS program was released in February of 1987. Since that time, many user comments and enhancements have been incorporated into the program providing a much more powerful and user-friendly system. This version has been designated IRRAS 4.0 and is the subject of this Reference Manual. Version 4.0 of IRRAS provides the same capabilities as Version 1.0 and adds a relational data base facility for managing the data, improved functionality, and improved algorithm performance.

  7. Distribution system reliability assessment using hierarchical Markov modeling

    SciTech Connect

    Brown, R.E.; Gupta, S.; Christie, R.D.; Venkata, S.S.; Fletcher, R.

    1996-10-01

    Distribution system reliability assessment is concerned with power availability and power quality at each customer`s service entrance. This paper presents a new method, termed Hierarchical Markov Modeling (HMM), which can perform predictive distribution system reliability assessment. HMM is unique in that it decomposes the reliability model based on system topology, integrated protection systems, and individual protection devices. This structure, which easily accommodates the effects of backup protection, fault isolation, and load restoration, is compared to simpler reliability models. HMM is then used to assess the reliability of an existing utility distribution system and to explore the reliability impact of several design improvement options.

  8. An Information Approach To Model Selection For Feedwater Inferential Measurements In A Nuclear Power Plant

    SciTech Connect

    Urmanov, Aleksey M.; Gribok, Andrei V.; Hines, J. Wesley; Uhrig, Robert E.

    2002-07-01

    Inferential sensing is a method that can be used to evaluate the parameters of a physical system based on a set of measurements related to those parameters. Inferential sensing uses mathematical models to infer the parameter value from correlated sensor values. However, inferential sensing is an ill-posed problem because of non-uniqueness and instability of the solution. This paper shows that complexity-penalized model selection can be used to produce a unique and stable solution. An important example of monitoring the nuclear power plant feedwater flow rate is given using data from Carolina Power and Light's Crystal River Nuclear Power Plant. (authors)

  9. Evaluation Applied to Reliability Analysis of Reconfigurable, Highly Reliable, Fault-Tolerant, Computing Systems for Avionics

    NASA Technical Reports Server (NTRS)

    Migneault, G. E.

    1979-01-01

    Emulation techniques are proposed as a solution to a difficulty arising in the analysis of the reliability of highly reliable computer systems for future commercial aircraft. The difficulty, viz., the lack of credible precision in reliability estimates obtained by analytical modeling techniques are established. The difficulty is shown to be an unavoidable consequence of: (1) a high reliability requirement so demanding as to make system evaluation by use testing infeasible, (2) a complex system design technique, fault tolerance, (3) system reliability dominated by errors due to flaws in the system definition, and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. The technique of emulation is described, indicating how its input is a simple description of the logical structure of a system and its output is the consequent behavior. The use of emulation techniques is discussed for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques.

  10. Mechanical system reliability for long life space systems

    NASA Technical Reports Server (NTRS)

    Kowal, Michael T.

    1994-01-01

    The creation of a compendium of mechanical limit states was undertaken in order to provide a reference base for the application of first-order reliability methods to mechanical systems in the context of the development of a system level design methodology. The compendium was conceived as a reference source specific to the problem of developing the noted design methodology, and not an exhaustive or exclusive compilation of mechanical limit states. The compendium is not intended to be a handbook of mechanical limit states for general use. The compendium provides a diverse set of limit-state relationships for use in demonstrating the application of probabilistic reliability methods to mechanical systems. The compendium is to be used in the reliability analysis of moderately complex mechanical systems.

  11. Augmenting system reliability analyses with observation priors

    SciTech Connect

    Lawrence, Earl; Anderson-cook, Christine

    2009-01-01

    Occasionally, a system may fail a test without an obvious component being at fault. Instead, experts may know that at least one of a set of components has failed, but there is uncertainty about which members in the set were the actual failures. When no further information is available, this missing data may be imputed using standard data augmentation (DA). This process is already used in the current implementation of the JMP complex-system reliability modeling codes. In some cases when this situation arises, there may be some supplemental information about the nature of the failure that suggests which subset of components are more likely to have failed. the behavior of the system during the failure may make certain components more likely candidates, and lead the engineering experts to have certain prior beliefs about what occurred. In this case, it is still known that at least one of a set of components failed, but the experts have some idea that certain failure scenarios are more likely than others. This white paper addresses this situation by modifying the imputation process of data augmentation through the use of an observation prior. This prior is specific to particular observations, and a given outcome which is repeated several times could potentially have different observation priors associated with each occurrence.

  12. Reliable, efficient systems for biomedical research facility

    SciTech Connect

    Basso, P.

    1997-05-01

    Medical Sciences Research Building III (MSRB III) is a 10-story, 207,000 ft{sup 2} (19,230 m{sup 2}) biomedical research facility on the campus of the University of Michigan. The design of MSRB III required a variety of technological solutions to complex design issues. The systems also had to accommodate future modifications. Closely integrated, modular systems with a high degree of flexibility were designed to respond to this requirement. Additionally, designs were kept as simple as possible for operation and maintenance personnel. Integrated electronic controls were used to provide vital data during troubleshooting and maintenance procedures. Equipment was also specified that provides reliability and minimizes maintenance. Other features include 100% redundancy of all central equipment servicing the animal housing area; redundant temperature controls for each individual animal housing room for fail-safe operation to protect the animals against overheating; and accessibility to all items requiring maintenance through an above-ceiling coordination process. It is critical that the engineering systems for MSRB III provide a safe, comfortable, energy efficient environment. The achievement of this design intent was noted by the University`s Commissioning Review Committee which stated: The Commissioning Process performed during both the design phase and construction phase of MSRB III was a significant success, providing an efficiently functioning facility that has been built in accordance with its design intent.

  13. Decomposition in reliability analysis of fault-tolerant systems

    NASA Technical Reports Server (NTRS)

    Trivedi, K. S.; Geist, R. M.

    1983-01-01

    The existing approaches to reliability modeling are briefly reviewed. An examination of the limitations of the existing approaches in modeling ultrareliable fault-tolerant systems illustrates the need to use decomposition techniques. The notion of behavioral decomposition is introduced for dealing with reliability models with a large number of states, and a series of examples is presented. The CARE (computer-aided reliability estimation) and HARP (hybrid automated reliability predictor) approaches to reliability are discussed.

  14. 75 FR 35689 - System Personnel Training Reliability Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-23

    ... Energy Regulatory Commission 18 CFR Part 40 System Personnel Training Reliability Standards June 17, 2010... approve Reliability Standards PER-005-1 (System Personnel Training) and PER- 004-2 (Reliability... coordinators, balancing authorities, and transmission operators to establish a training program for...

  15. Reliability program requirements for aeronautical and space system contractors

    NASA Technical Reports Server (NTRS)

    1987-01-01

    General reliability program requirements for NASA contracts involving the design, development, fabrication, test, and/or use of aeronautical and space systems including critical ground support equipment are prescribed. The reliability program requirements require (1) thorough planning and effective management of the reliability effort; (2) definition of the major reliability tasks and their place as an integral part of the design and development process; (3) planning and evaluating the reliability of the system and its elements (including effects of software interfaces) through a program of analysis, review, and test; and (4) timely status indication by formal documentation and other reporting to facilitate control of the reliability program.

  16. 75 FR 81152 - Interpretation of Protection System Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-27

    ... Energy Regulatory Commission 18 CFR Part 40 Interpretation of Protection System Reliability Standard... rulemaking. SUMMARY: The North American Electric Reliability Corporation (NERC) has submitted a petition (Petition) requesting approval of NERC's interpretation of Requirement R1 of Commission-approved...

  17. Ethanolamine properties and use for feedwater pH control: A pressurized water reactor case study

    SciTech Connect

    Keeling, D.L.; Polidoroff, C.T.; Cortese, S.; Cushner, M.C.

    1995-12-31

    Ethanolamine (ETA) as a feedwater pH control additive has been recently used to minimize corrosion of secondary water components in the nuclear power industry pressurized water reactors (PWRs). The use of ETA is compared with ammonia. Relative volatility effects on various parts of the system are analyzed and chemistry changes are presented. Materials of construction and the use of existing plant equipment for ETA service are discussed. Properties of ETA as well as safety, storage and handling issues are compared with ammonia. Health d aquatic toxicity are reviewed. warnings, safety, handling guidelines, biodegradability an Diablo Canyon Power Plant used ammonia for pH control from 1985 until a change over to ETA in 1993/1994. Full flow condensate polishers that are required to protect the plant from saltwater cooling incursions limit the amount of pH additive. Iron levels in the secondary water systems are compared before and after changing to ETA and replacement of corrosion-susceptible piping. Iron reduction benefits are assessed along with other effects on the feedwater nozzles, low pressure turbine, polisher resin capacity and polisher regeneration system.

  18. Assessment of RELAP5/MOD2 against a main feedwater turbopump trip transient in the Vandellos II Nuclear Power Plant

    SciTech Connect

    Llopis, C.; Casals, A.; Perez, J.; Mendizabal, R.

    1993-12-01

    The Consejo de Seguridad Nuclear (CSN) and the Asociacion Nuclear Vandellos (ANV) have developed a model of Vandellos II Nuclear Power Plant. The ANV collaboration consisted in the supply of design and actual data, the cooperation in the simulation of the control systems and other model components, as well as in the results analysis. The obtained model has been assessed against the following transients occurred in plant: A trip from the 100% power level (CSN); a load rejection from 100% to 50% (CSN); a load rejection from 75% to 65% (ANV); and, a feedwater turbopump trip (ANV). This copy is a report of the feedwater turbopump trip transient simulation. This transient actually occurred in the plant on June 19, 1989.

  19. User's guide to the Reliability Estimation System Testbed (REST)

    NASA Technical Reports Server (NTRS)

    Nicol, David M.; Palumbo, Daniel L.; Rifkin, Adam

    1992-01-01

    The Reliability Estimation System Testbed is an X-window based reliability modeling tool that was created to explore the use of the Reliability Modeling Language (RML). RML was defined to support several reliability analysis techniques including modularization, graphical representation, Failure Mode Effects Simulation (FMES), and parallel processing. These techniques are most useful in modeling large systems. Using modularization, an analyst can create reliability models for individual system components. The modules can be tested separately and then combined to compute the total system reliability. Because a one-to-one relationship can be established between system components and the reliability modules, a graphical user interface may be used to describe the system model. RML was designed to permit message passing between modules. This feature enables reliability modeling based on a run time simulation of the system wide effects of a component's failure modes. The use of failure modes effects simulation enhances the analyst's ability to correctly express system behavior when using the modularization approach to reliability modeling. To alleviate the computation bottleneck often found in large reliability models, REST was designed to take advantage of parallel processing on hypercube processors.

  20. Guided UT wave inspection of insulated feedwater piping using magnetostrictive sensors

    NASA Astrophysics Data System (ADS)

    Brophy, J. W.; Brett, Colin R.

    1996-11-01

    Due to failures in power plant feedwater piping, inspection of these components has become a priority item. The major reason for the failures is wall loss due to flow-accelerated corrosion on the inside diameter (ID) of the pipes. It can be very costly to use standard nondestructive testing (NDT) techniques for a comprehensive inspection due to the need to remove large areas of insulation. Guided UT waves can travel through the pipe over long distances and detect cross- sectional changes in the pipe wall with minimal insulation removal. This makes the guided UT wave an excellent candidate for locating significant wall loss due to corrosion and pitting. Southwest Research Institute (SwRI) has developed a simple and robust technology for generating and receiving guided UT waves based on magnetorestrictive sensors. Signals are generated and detected in the pipe via multi-turn coils acting as transmitters and receivers. Insulation removal is only required where the coils are attached to the pipe and this allows many meters of pipe to be inspected from a single location. Guided UT waves detect cross-sectional changes from corrosion on both the ID and outside diameter of the pipe and can also be used to map weld locations. This paper describes SwRIs systems and the preliminary results from testing on a feedwater pipe mockup containing simulated flow-accelerated corrosion.

  1. The 747 primary flight control systems reliability and maintenance study

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The major operational characteristics of the 747 Primary Flight Control Systems (PFCS) are described. Results of reliability analysis for separate control functions are presented. The analysis makes use of a NASA computer program which calculates reliability of redundant systems. Costs for maintaining the 747 PFCS in airline service are assessed. The reliabilities and cost will provide a baseline for use in trade studies of future flight control system design.

  2. Comprehensive Design Reliability Activities for Aerospace Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Christenson, R. L.; Whitley, M. R.; Knight, K. C.

    2000-01-01

    This technical publication describes the methodology, model, software tool, input data, and analysis result that support aerospace design reliability studies. The focus of these activities is on propulsion systems mechanical design reliability. The goal of these activities is to support design from a reliability perspective. Paralleling performance analyses in schedule and method, this requires the proper use of metrics in a validated reliability model useful for design, sensitivity, and trade studies. Design reliability analysis in this view is one of several critical design functions. A design reliability method is detailed and two example analyses are provided-one qualitative and the other quantitative. The use of aerospace and commercial data sources for quantification is discussed and sources listed. A tool that was developed to support both types of analyses is presented. Finally, special topics discussed include the development of design criteria, issues of reliability quantification, quality control, and reliability verification.

  3. Optimization of life support systems and their systems reliability

    NASA Technical Reports Server (NTRS)

    Fan, L. T.; Hwang, C. L.; Erickson, L. E.

    1971-01-01

    The identification, analysis, and optimization of life support systems and subsystems have been investigated. For each system or subsystem that has been considered, the procedure involves the establishment of a set of system equations (or mathematical model) based on theory and experimental evidences; the analysis and simulation of the model; the optimization of the operation, control, and reliability; analysis of sensitivity of the system based on the model; and, if possible, experimental verification of the theoretical and computational results. Research activities include: (1) modeling of air flow in a confined space; (2) review of several different gas-liquid contactors utilizing centrifugal force: (3) review of carbon dioxide reduction contactors in space vehicles and other enclosed structures: (4) application of modern optimal control theory to environmental control of confined spaces; (5) optimal control of class of nonlinear diffusional distributed parameter systems: (6) optimization of system reliability of life support systems and sub-systems: (7) modeling, simulation and optimal control of the human thermal system: and (8) analysis and optimization of the water-vapor eletrolysis cell.

  4. Reliability of digital reactor protection system based on extenics.

    PubMed

    Zhao, Jing; He, Ya-Nan; Gu, Peng-Fei; Chen, Wei-Hua; Gao, Feng

    2016-01-01

    After the Fukushima nuclear accident, safety of nuclear power plants (NPPs) is widespread concerned. The reliability of reactor protection system (RPS) is directly related to the safety of NPPs, however, it is difficult to accurately evaluate the reliability of digital RPS. The method is based on estimating probability has some uncertainties, which can not reflect the reliability status of RPS dynamically and support the maintenance and troubleshooting. In this paper, the reliability quantitative analysis method based on extenics is proposed for the digital RPS (safety-critical), by which the relationship between the reliability and response time of RPS is constructed. The reliability of the RPS for CPR1000 NPP is modeled and analyzed by the proposed method as an example. The results show that the proposed method is capable to estimate the RPS reliability effectively and provide support to maintenance and troubleshooting of digital RPS system.

  5. Reliability of Fault Tolerant Control Systems. Part 1

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    2001-01-01

    This paper reports Part I of a two part effort, that is intended to delineate the relationship between reliability and fault tolerant control in a quantitative manner. Reliability analysis of fault-tolerant control systems is performed using Markov models. Reliability properties, peculiar to fault-tolerant control systems are emphasized. As a consequence, coverage of failures through redundancy management can be severely limited. It is shown that in the early life of a syi1ein composed of highly reliable subsystems, the reliability of the overall system is affine with respect to coverage, and inadequate coverage induces dominant single point failures. The utility of some existing software tools for assessing the reliability of fault tolerant control systems is also discussed. Coverage modeling is attempted in Part II in a way that captures its dependence on the control performance and on the diagnostic resolution.

  6. Reliable data acquisition for inspection systems

    NASA Astrophysics Data System (ADS)

    Silva, V. P.; Silva, D. S.; Boccardo, D. R.; Machado, R. C. S.; Carmo, L. F. R. C.

    2015-01-01

    In Brazil, the road transportation of dangerous goods is subject to regulatory control, which is conducted by Inmetro, the National Institute of Metrology, Quality and Technology. Currently, the process of monitoring such inspections is done manually, leaving the possibility of some inconsistencies: inspections held outside the authorized local inspection, incorrectly, incompletely, or even be held. Thus, in order to increase the reliability of such inspections, it is needed a closer monitoring by the regulatory agency. One approach towards that, is the implementation of an automated process in which evidences are collected in a reliable way during the inspections, enabling further analyses. This work employs security mechanisms on a portable device to ensure the confidence of the evidences collected during an inspection, paving the way for later more robust analyzes.

  7. Bayesian Missile System Reliability from Point Estimates

    DTIC Science & Technology

    2014-10-28

    AVAILABILITY STATEMENT Approved for public release, distribution unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT This paper applies the Maximum Entropy ...reliability, maximum entropy 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT SAR 18. NUMBER OF PAGES 13 19a. NAME OF RESPONSIBLE PERSON a...assessment. In this paper, we propose using the Maximum Entropy Principle (MEP) to convert point estimates or design values, as obtained pro forma from

  8. Feedwater heater life optimization at Peach Bottom Atomic Power Station

    SciTech Connect

    Catapano, M.C.; Thomas, D.S.

    1995-12-01

    Many papers published over the last 15 years have strongly emphasized the need for an ongoing program of inspection and testing with subsequent failure cause analysis of feedwater heaters. With deregulation of the electric utility industry in various phases of implementation, utilities must decrease costs, both O&M and capital, while optimizing plant efficiency. In order to accomplish this coal, utility engineers must monitor feedwater heater performance in order to recognize degradation, correct/eliminate failure mechanisms, and prevent in-service failures while optimizing availability. Periodic tube plugging without complete analysis of the degraded/failed area resolves the immediate need for return for service, however, heater life will not be graded/failed area resolves optimized. This paper illustrates a complete inspection, testing, and maintenance program implemented at PECO Energy`s Peach Bottom Atomic Power Station (PBAPS). Concerns that tubes may have been too conservatively plugged due to insufficient data justified a program that included: (1) Removal of previously installed plugs. (2) Videoprobe inspection of failed areas. (3) Extraction of tube samples for further analysis. (4) Eddy current testing of selected tubes. (5) Evaluation of the condition of {open_quotes}insurance{close_quotes} plugged tubes for return to service. (6) Hydrostatic testing of selected tubes. (7) Final repair plan based on the results of the above program. This paper concludes that no single method of inspection or testing should solely be relied upon in establishing: (1) The extent of actual degraded conditions, (2) The source(s) of failure mechanisms, (3) The details of repair. It is a combination of all gathered data that affords the best chance in arresting problems and optimizing feedwater heater life.

  9. Evaluation of reliability modeling tools for advanced fault tolerant systems

    NASA Technical Reports Server (NTRS)

    Baker, Robert; Scheper, Charlotte

    1986-01-01

    The Computer Aided Reliability Estimation (CARE III) and Automated Reliability Interactice Estimation System (ARIES 82) reliability tools for application to advanced fault tolerance aerospace systems were evaluated. To determine reliability modeling requirements, the evaluation focused on the Draper Laboratories' Advanced Information Processing System (AIPS) architecture as an example architecture for fault tolerance aerospace systems. Advantages and limitations were identified for each reliability evaluation tool. The CARE III program was designed primarily for analyzing ultrareliable flight control systems. The ARIES 82 program's primary use was to support university research and teaching. Both CARE III and ARIES 82 were not suited for determining the reliability of complex nodal networks of the type used to interconnect processing sites in the AIPS architecture. It was concluded that ARIES was not suitable for modeling advanced fault tolerant systems. It was further concluded that subject to some limitations (the difficulty in modeling systems with unpowered spare modules, systems where equipment maintenance must be considered, systems where failure depends on the sequence in which faults occurred, and systems where multiple faults greater than a double near coincident faults must be considered), CARE III is best suited for evaluating the reliability of advanced tolerant systems for air transport.

  10. Shunt capacitor effect on electrical distribution system reliability

    NASA Astrophysics Data System (ADS)

    Sallam, Abdelhay A.; Desouky, Mohamed; Desouky, Hussien

    1994-03-01

    To improve the security & reliability of a distribution system, as much power as feasible must go through a given transmission line. This can be achieved by using shunt capacitors as compensators. These shunt capacitive compensators improve the load carrying capability of the line by controlling the reactive power flow. Consequently, the capacitor existence can not be ignored in evaluating system reliability. The paper applies the state-space method to calculate the reliability indices for compensated & uncompensated systems with different success criteria. The importance of using shunt capacitors to improve the level of distribution system reliability is illustrated in addition to their original function as reactive power controllers. Our procedure, based on a Markov process, is applied to a numerical example, and indicates that system reliability is improved when using shunt capacitors.

  11. Systems reliability analysis for the national ignition facility

    SciTech Connect

    Majumdar, K.C.; Annese, C.E.; MacIntyre, A.T.; Sicherman, A.

    1996-06-12

    A Reliability, Availability and Maintainability (RAM) analysis was initiated for the National Ignition Facility (NIF). The NIF is an inertial confinement fusion research facility designed to achieve controlled thermonuclear reaction; the preferred site for the NIF is the Lawrence Livermore National Laboratory (LLNL). The NIF RAM analysis has three purposes: (1) to allocate top level reliability and availability goals for the systems, (2) to develop an operability model for optimum maintainability, and (3) to determine the achievability of the allocated goals of the RAM parameters for the NIF systems and the facility operation as a whole. An allocation model assigns the reliability and availability goals for front line and support systems by a top-down approach; reliability analysis uses a bottom-up approach to determine the system reliability and availability from component level to system level.

  12. Reliability models applicable to space telescope solar array assembly system

    NASA Technical Reports Server (NTRS)

    Patil, S. A.

    1986-01-01

    A complex system may consist of a number of subsystems with several components in series, parallel, or combination of both series and parallel. In order to predict how well the system will perform, it is necessary to know the reliabilities of the subsystems and the reliability of the whole system. The objective of the present study is to develop mathematical models of the reliability which are applicable to complex systems. The models are determined by assuming k failures out of n components in a subsystem. By taking k = 1 and k = n, these models reduce to parallel and series models; hence, the models can be specialized to parallel, series combination systems. The models are developed by assuming the failure rates of the components as functions of time and as such, can be applied to processes with or without aging effects. The reliability models are further specialized to Space Telescope Solar Arrray (STSA) System. The STSA consists of 20 identical solar panel assemblies (SPA's). The reliabilities of the SPA's are determined by the reliabilities of solar cell strings, interconnects, and diodes. The estimates of the reliability of the system for one to five years are calculated by using the reliability estimates of solar cells and interconnects given n ESA documents. Aging effects in relation to breaks in interconnects are discussed.

  13. Reliability studies of integrated modular engine system designs

    NASA Technical Reports Server (NTRS)

    Hardy, Terry L.; Rapp, Douglas C.

    1993-01-01

    A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented.

  14. Reliability studies of Integrated Modular Engine system designs

    NASA Technical Reports Server (NTRS)

    Hardy, Terry L.; Rapp, Douglas C.

    1993-01-01

    A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented.

  15. Reliability studies of integrated modular engine system designs

    NASA Astrophysics Data System (ADS)

    Hardy, Terry L.; Rapp, Douglas C.

    1993-06-01

    A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented.

  16. Reliability studies of Integrated Modular Engine system designs

    NASA Astrophysics Data System (ADS)

    Hardy, Terry L.; Rapp, Douglas C.

    1993-06-01

    A study was performed to evaluate the reliability of Integrated Modular Engine (IME) concepts. Comparisons were made between networked IME systems and non-networked discrete systems using expander cycle configurations. Both redundant and non-redundant systems were analyzed. Binomial approximation and Markov analysis techniques were employed to evaluate total system reliability. In addition, Failure Modes and Effects Analyses (FMEA), Preliminary Hazard Analyses (PHA), and Fault Tree Analysis (FTA) were performed to allow detailed evaluation of the IME concept. A discussion of these system reliability concepts is also presented.

  17. Results of a Demonstration Assessment of Passive System Reliability Utilizing the Reliability Method for Passive Systems (RMPS)

    SciTech Connect

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia; Grelle, Austin

    2015-04-26

    Advanced small modular reactor designs include many advantageous design features such as passively driven safety systems that are arguably more reliable and cost effective relative to conventional active systems. Despite their attractiveness, a reliability assessment of passive systems can be difficult using conventional reliability methods due to the nature of passive systems. Simple deviations in boundary conditions can induce functional failures in a passive system, and intermediate or unexpected operating modes can also occur. As part of an ongoing project, Argonne National Laboratory is investigating various methodologies to address passive system reliability. The Reliability Method for Passive Systems (RMPS), a systematic approach for examining reliability, is one technique chosen for this analysis. This methodology is combined with the Risk-Informed Safety Margin Characterization (RISMC) approach to assess the reliability of a passive system and the impact of its associated uncertainties. For this demonstration problem, an integrated plant model of an advanced small modular pool-type sodium fast reactor with a passive reactor cavity cooling system is subjected to a station blackout using RELAP5-3D. This paper discusses important aspects of the reliability assessment, including deployment of the methodology, the uncertainty identification and quantification process, and identification of key risk metrics.

  18. PV system field experience and reliability

    NASA Astrophysics Data System (ADS)

    Durand, Steven; Rosenthal, Andrew; Thomas, Mike

    1997-02-01

    Hybrid power systems consisting of battery inverters coupled with diesel, propane, or gasoline engine-driven electrical generators, and photovoltaic arrays are being used in many remote locations. The potential cost advantages of hybrid systems over simple engine-driven generator systems are causing hybrid systems to be considered for numerous applications including single-family residential, communications, and village power. This paper discusses the various design constraints of such systems and presents one technique for reducing hybrid system losses. The Southwest Technology Development Institute under contract to the National Renewable Energy Laboratory and Sandia National Laboratories has been installing data acquisition systems (DAS) on a number of small and large hybrid PV systems. These systems range from small residential systems (1 kW PV - 7 kW generator), to medium sized systems (10 kW PV - 20 kW generator), to larger systems (100 kW PV - 200 kW generator). Even larger systems are being installed with hundreds of kilowatts of PV modules, multiple wind machines, and larger diesel generators.

  19. Reliability analysis and initial requirements for FC systems and stacks

    NASA Astrophysics Data System (ADS)

    Åström, K.; Fontell, E.; Virtanen, S.

    In the year 2000 Wärtsilä Corporation started an R&D program to develop SOFC systems for CHP applications. The program aims to bring to the market highly efficient, clean and cost competitive fuel cell systems with rated power output in the range of 50-250 kW for distributed generation and marine applications. In the program Wärtsilä focuses on system integration and development. System reliability and availability are key issues determining the competitiveness of the SOFC technology. In Wärtsilä, methods have been implemented for analysing the system in respect to reliability and safety as well as for defining reliability requirements for system components. A fault tree representation is used as the basis for reliability prediction analysis. A dynamic simulation technique has been developed to allow for non-static properties in the fault tree logic modelling. Special emphasis has been placed on reliability analysis of the fuel cell stacks in the system. A method for assessing reliability and critical failure predictability requirements for fuel cell stacks in a system consisting of several stacks has been developed. The method is based on a qualitative model of the stack configuration where each stack can be in a functional, partially failed or critically failed state, each of the states having different failure rates and effects on the system behaviour. The main purpose of the method is to understand the effect of stack reliability, critical failure predictability and operating strategy on the system reliability and availability. An example configuration, consisting of 5 × 5 stacks (series of 5 sets of 5 parallel stacks) is analysed in respect to stack reliability requirements as a function of predictability of critical failures and Weibull shape factor of failure rate distributions.

  20. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, T.; Toon, J.; Conner, A.; Adams, T.; Miranda, D.

    2016-01-01

    This paper describes the methodology and value of modifying allocations to reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) programs subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. This iterative process provided an opportunity for the reliability engineering team to reevaluate allocations as systems moved beyond their conceptual and preliminary design phases. These new allocations are based on updated designs and maintainability characteristics of the components. It was found that trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper discusses the results of reliability and maintainability reallocations made for the GSDO subsystems as the program nears the end of its design phase.

  1. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, Jamie; Toon, Troy; Adams, Timothy C.; Miranda, David J.

    2016-01-01

    This paper describes the methodology that was developed to allocate reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) program's subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. Allocating is an iterative process; as systems moved beyond their conceptual and preliminary design phases this provided an opportunity for the reliability engineering team to reevaluate allocations based on updated designs and maintainability characteristics of the components. Trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper will discuss the value of modifying reliability and maintainability allocations made for the GSDO subsystems as the program nears the end of its design phase.

  2. Evolving Reliability and Maintainability Allocations for NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Munoz, Gisela; Toon, Troy; Toon, Jamie; Conner, Angelo C.; Adams, Timothy C.; Miranda, David J.

    2016-01-01

    This paper describes the methodology and value of modifying allocations to reliability and maintainability requirements for the NASA Ground Systems Development and Operations (GSDO) program’s subsystems. As systems progressed through their design life cycle and hardware data became available, it became necessary to reexamine the previously derived allocations. This iterative process provided an opportunity for the reliability engineering team to reevaluate allocations as systems moved beyond their conceptual and preliminary design phases. These new allocations are based on updated designs and maintainability characteristics of the components. It was found that trade-offs in reliability and maintainability were essential to ensuring the integrity of the reliability and maintainability analysis. This paper discusses the results of reliability and maintainability reallocations made for the GSDO subsystems as the program nears the end of its design phase.

  3. The reliability of an epilepsy treatment clinical decision support system.

    PubMed

    Standridge, Shannon; Faist, Robert; Pestian, John; Glauser, Tracy; Ittenbach, Richard

    2014-10-01

    We developed a content validated computerized epilepsy treatment clinical decision support system to assist clinicians with selecting the best antiepilepsy treatments. Before disseminating our computerized epilepsy treatment clinical decision support system, further rigorous validation testing was necessary. As reliability is a precondition of validity, we verified proof of reliability first. We evaluated the consistency of the epilepsy treatment clinical decision support system in three areas including the preferred antiepilepsy drug choice, the top three recommended choices, and the rank order of the three choices. We demonstrated 100% reliability on 15,000 executions involving a three-step process on five different common pediatric epilepsy syndromes. Evidence for the reliability of the epilepsy treatment clinical decision support system was essential for the long-term viability of the system, and served as a crucial component for the next phase of system validation.

  4. Application of reliability concepts to the Nepal power system

    SciTech Connect

    Billinton, R.; Pandey, M.; Aboreshaid, S.; Fotuhi-Firuzabad, M.

    1995-12-31

    In many of the less industrialized countries throughout the world, reliability is incorporated in power system planning and operation using traditional deterministic techniques. This is the case with the Nepal Power System (NPS), where developed expansion plans have been based on non-probabilistic criteria. This paper illustrates the application of probabilistic methods to reliability evaluation of the NPS. Evaluations at both the generation and composite generation and transmission system levels have been performed. The overall system and nine major load centers have been assessed. These load points carry in total more than 54% of the system load. An assessment of an expansion plan proposed by the Nepal Electricity Authority (NEA) has been performed. The results indicate the reliability implications associated with the system and the proposed expansion plan, and show that quantitative reliability evaluation of the NPS is both possible and practical.

  5. A System for Integrated Reliability and Safety Analyses

    NASA Technical Reports Server (NTRS)

    Kostiuk, Peter; Shapiro, Gerald; Hanson, Dave; Kolitz, Stephan; Leong, Frank; Rosch, Gene; Coumeri, Marc; Scheidler, Peter, Jr.; Bonesteel, Charles

    1999-01-01

    We present an integrated reliability and aviation safety analysis tool. The reliability models for selected infrastructure components of the air traffic control system are described. The results of this model are used to evaluate the likelihood of seeing outcomes predicted by simulations with failures injected. We discuss the design of the simulation model, and the user interface to the integrated toolset.

  6. Techniques for increasing the reliability of accelerator control system electronics

    SciTech Connect

    Utterback, J.

    1993-09-01

    As the physical size of modern accelerators becomes larger and larger, the number of required control system circuit boards increases, and the probability of one of those circuit boards failing while in service also increases. In order to do physics, the experimenters need the accelerator to provide beam reliably with as little down time as possible. With the advent of colliding beams physics, reliability becomes even more important due to the fact that a control system failure can cause the loss of painstakingly produced antiprotons. These facts prove the importance of keeping reliability in mind when designing and maintaining accelerator control system electronics.

  7. Reliability Growth Analysis of Satellite Systems

    DTIC Science & Technology

    2012-09-01

    obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that of a...parameters are obtained. In addition, the Cumulative Intensity Function ( CIF ) of a family of satellite systems was analyzed to assess its similarity to that...System Figures 7a through 7i display the real CIF for a variety of GOES missions. These cumulative intensity functions have shapes similar to the

  8. Reliability model of a monopropellant auxiliary propulsion system

    NASA Technical Reports Server (NTRS)

    Greenberg, J. S.

    1971-01-01

    A mathematical model and associated computer code has been developed which computes the reliability of a monopropellant blowdown hydrazine spacecraft auxiliary propulsion system as a function of time. The propulsion system is used to adjust or modify the spacecraft orbit over an extended period of time. The multiple orbit corrections are the multiple objectives which the auxiliary propulsion system is designed to achieve. Thus the reliability model computes the probability of successfully accomplishing each of the desired orbit corrections. To accomplish this, the reliability model interfaces with a computer code that models the performance of a blowdown (unregulated) monopropellant auxiliary propulsion system. The computer code acts as a performance model and as such gives an accurate time history of the system operating parameters. The basic timing and status information is passed on to and utilized by the reliability model which establishes the probability of successfully accomplishing the orbit corrections.

  9. A high reliability battery management system

    NASA Technical Reports Server (NTRS)

    Moody, M. H.

    1986-01-01

    Over a period of some 5 years Canadian Astronautics Limited (CAL) has developed a system to autonomously manage, and thus prolong the life of, secondary storage batteries. During the development, the system was aimed at the space vehicle application using nickel cadmium batteries, but is expected to be able to enhance the life and performance of any rechargeable electrochemical couple. The system handles the cells of a battery individually and thus avoids the problems of over, and under, drive that inevitably occur in a battery of cells managed by an averaging system. This individual handling also allow cells to be totally bypassed in the event of failure, thus avoiding the losses associated with low capacity, partial short circuit, and the catastrophe of open circuit. The system has an optional capability of managing redundant batteries simultaneously, adding the advantage of on line reconditioning of one battery, while the other maintains the energy storage capability of the overall system. As developed, the system contains a dedicated, redundant, microprocessor, but the capability exists to have this computing capability time shared, or remote, and operating through a data link. As adjuncts to the basic management system CAL has developed high efficiency, polyphase, power regulators for charge and discharge power conditioning.

  10. Survey and characterization of feedwater venture fouling at nuclear power plants. Volume 1, Feedwater venturi fouling: Final report

    SciTech Connect

    Allmon, W.E.; Sarver, L.W.; Boyce, S.L.; Lamanna, L.S.; Lucero, V.A.; Koch, D.W.

    1992-05-01

    Fouling of feedwater venturis in nuclear power generating plants was investigated by a survey of seven plants and by venturi inspections and deposit analyses at three plants. The information in this report will be useful to plant operators and chemists and to those involved in venturi manufacturing and calibration. Video inspection and SEM/EDS analyses show that deposits follow machining and polishing marks and that deposits accumulate on areas of abrupt flow transition. Also, corrosion of copper alloys downstream of the condensate polishers results in venturi fouling. The results indicate that feedwater venturi fouling can be minimized by (a) minimizing sharp flow transitions and turbulence within the venturis, (b) enhancing the surface smoothness, for example, by electropolishing, (c) minimizing copper-bearing alloys in the balance-of-plant, especially downstream of the condensate polishers, (d) minimizing exposure of the venturis to high concentrations of corrosion products during preoperational cleanup, and (e) minimizing the design velocity and/or pressure drop through the venturis. Alternate water chemistry, such as morpholine or other amines, for reducing venturi fouling was not investigated since most PWR plants had only recently converted to an alternate chemistry.

  11. Reliability analysis of ship structure system with multi-defects

    NASA Astrophysics Data System (ADS)

    An, Hai; An, Weigang; Zhao, Weitao

    2010-11-01

    This paper analyzes the influence of multi-defects including the initial distortions, welding residual stresses, cracks and local dents on the ultimate strength of the plate element, and has worked out expressions of reliability calculation and sensitivity analysis of the plate element. Reliability analysis is made for the system with multi-defects plate elements. Failure mechanism, failure paths and the calculating approach to global reliability index are also worked out. After plate elements with multi-defects fail, the formula of reverse node forces which affect the residual structure is deduced, so are the sensitivity expressions of the system reliability index. This ensures calculating accuracy and rationality for reliability analysis, and makes it convenient to find weakness plate elements which affect the reliability of the structure system. Finally, for the validity of the approach proposed, we take the numerical example of a ship cabin to compare and contrast the reliability and the sensitivity analysis of the structure system with multi-defects with those of the structure system with no defects. The approach has implications for the structure design, rational maintenance and renewing strategy.

  12. A Passive System Reliability Analysis for a Station Blackout

    SciTech Connect

    Brunett, Acacia; Bucknor, Matthew; Grabaskas, David; Sofu, Tanju; Grelle, Austin

    2015-05-03

    The latest iterations of advanced reactor designs have included increased reliance on passive safety systems to maintain plant integrity during unplanned sequences. While these systems are advantageous in reducing the reliance on human intervention and availability of power, the phenomenological foundations on which these systems are built require a novel approach to a reliability assessment. Passive systems possess the unique ability to fail functionally without failing physically, a result of their explicit dependency on existing boundary conditions that drive their operating mode and capacity. Argonne National Laboratory is performing ongoing analyses that demonstrate various methodologies for the characterization of passive system reliability within a probabilistic framework. Two reliability analysis techniques are utilized in this work. The first approach, the Reliability Method for Passive Systems, provides a mechanistic technique employing deterministic models and conventional static event trees. The second approach, a simulation-based technique, utilizes discrete dynamic event trees to treat time- dependent phenomena during scenario evolution. For this demonstration analysis, both reliability assessment techniques are used to analyze an extended station blackout in a pool-type sodium fast reactor (SFR) coupled with a reactor cavity cooling system (RCCS). This work demonstrates the entire process of a passive system reliability analysis, including identification of important parameters and failure metrics, treatment of uncertainties and analysis of results.

  13. Diverse Redundant Systems for Reliable Space Life Support

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.

    2015-01-01

    Reliable life support systems are required for deep space missions. The probability of a fatal life support failure should be less than one in a thousand in a multi-year mission. It is far too expensive to develop a single system with such high reliability. Using three redundant units would require only that each have a failure probability of one in ten over the mission. Since the system development cost is inverse to the failure probability, this would cut cost by a factor of one hundred. Using replaceable subsystems instead of full systems would further cut cost. Using full sets of replaceable components improves reliability more than using complete systems as spares, since a set of components could repair many different failures instead of just one. Replaceable components would require more tools, space, and planning than full systems or replaceable subsystems. However, identical system redundancy cannot be relied on in practice. Common cause failures can disable all the identical redundant systems. Typical levels of common cause failures will defeat redundancy greater than two. Diverse redundant systems are required for reliable space life support. Three, four, or five diverse redundant systems could be needed for sufficient reliability. One system with lower level repair could be substituted for two diverse systems to save cost.

  14. Allocating SMART Reliability and Maintainability Goals to NASA Ground Systems

    NASA Technical Reports Server (NTRS)

    Gillespie, Amanda; Monaghan, Mark

    2013-01-01

    This paper will describe the methodology used to allocate Reliability and Maintainability (R&M) goals to Ground Systems Development and Operations (GSDO) subsystems currently being designed or upgraded.

  15. Reliability assessment of autonomous power systems incorporating HVDC interconnection links

    SciTech Connect

    Dialynas, E.N.; Koskolos, N.C.; Agoris, D.

    1996-01-01

    The objective of this paper is to present an improved computational method for the overall reliability assessment of autonomous power systems that may or may not contain HVdc interconnection links. This is a hybrid method based on a Monte-Carlo simulation sequential approach which incorporates an analytical approach for the reliability modeling of the HVdc transmission links. The developed models and techniques have been implemented into a computer program that can be used to simulate the operational practices and characteristics of the overall system under study efficiently and realistically. A set of reliability indices are calculated for each load-point of interest and the entire system while a set of additional indices is calculated for quantifying the reliability performance of the interconnection links under the specified operating requirements. The analysis of a practical system is also included for a number of studies representing its various operating and design characteristics.

  16. Software reliability and safety in nuclear reactor protection systems

    SciTech Connect

    Lawrence, J.D.

    1993-11-01

    Planning the development, use and regulation of computer systems in nuclear reactor protection systems in such a way as to enhance reliability and safety is a complex issue. This report is one of a series of reports from the Computer Safety and Reliability Group, Lawrence Livermore that investigates different aspects of computer software in reactor National Laboratory, that investigates different aspects of computer software in reactor protection systems. There are two central themes in the report, First, software considerations cannot be fully understood in isolation from computer hardware and application considerations. Second, the process of engineering reliability and safety into a computer system requires activities to be carried out throughout the software life cycle. The report discusses the many activities that can be carried out during the software life cycle to improve the safety and reliability of the resulting product. The viewpoint is primarily that of the assessor, or auditor.

  17. Synthetical Reliability Analysis Model of CNC Software System

    NASA Astrophysics Data System (ADS)

    Xu, Yue; Xia, Yinjie; Wan, Yi

    CNC technology is the core of advanced manufacturing technology, and CNC software system is the very important part of numerical control system. The entire CNC system will not work normally, once the potential failure makes the software invalid. As to the current study of CNC sysytem, in use of the FAULT glitch tree, established a glitch tree for the CNC system; find the minimum cut sets with Fussed method and then according to the probability of several common glitches, make quantitative analysis in the reliability of the CNC system so that scientific ways can be provided for the reliability design, maintenance and management of the CNC system.

  18. Reliability analysis of a repairable duplex system

    NASA Astrophysics Data System (ADS)

    Vanderperre, E. J.; Makhanov, S. S.

    2014-09-01

    We analyse the survival time of a repairable duplex system characterised by cold standby and by a pre-emptive priority rule. We allow general probability distributions for failure and repair. Moreover, an important realistic feature of the system is the general assumption that the non-priority unit has a memory. This combination of features has not been analysed in the previous literature. Our (new) methodology is based on a concatenation of a Cauchy-type integral representation of the modified Heaviside unit-step function and a two-sided stochastic inequality. Finally, we introduce a security interval related to a security level and a suitable risk-criterion based on the survival function of the system. As a practical application, we analyse some particular cases of the survival function jointly with the security interval corresponding to a security level of 90.

  19. Systems Issues In Terrestrial Fiber Optic Link Reliability

    NASA Astrophysics Data System (ADS)

    Spencer, James L.; Lewin, Barry R.; Lee, T. Frank S.

    1990-01-01

    This paper reviews fiber optic system reliability issues from three different viewpoints - availability, operating environment, and evolving technologies. Present availability objectives for interoffice links and for the distribution loop must be re-examined for applications such as the Synchronous Optical Network (SONET), Fiber-to-the-Home (FTTH), and analog services. The hostile operating environments of emerging applications (such as FTTH) must be carefully considered in system design as well as reliability assessments. Finally, evolving technologies might require the development of new reliability testing strategies.

  20. The ATS F&G systems reliability program.

    NASA Technical Reports Server (NTRS)

    Doyle, H.

    1972-01-01

    Assurance of reliability, quality, and proper testing requires a large coordinating effort and a means for connecting the various areas involved. All parts used on the spacecraft are required to meet strict specifications and consequently must be approved by the systems reliability manager. The parts program has access to a computer data bank into which all information concerning nonstandard parts approval requests has been stored. Through the data bank, the system collects and distributes timely information concerning quality and reliability to all departments that may be concerned.

  1. Reliability models for dataflow computer systems

    NASA Technical Reports Server (NTRS)

    Kavi, K. M.; Buckles, B. P.

    1985-01-01

    The demands for concurrent operation within a computer system and the representation of parallelism in programming languages have yielded a new form of program representation known as data flow (DENN 74, DENN 75, TREL 82a). A new model based on data flow principles for parallel computations and parallel computer systems is presented. Necessary conditions for liveness and deadlock freeness in data flow graphs are derived. The data flow graph is used as a model to represent asynchronous concurrent computer architectures including data flow computers.

  2. Component Reliability Database for Weapons Systems

    DTIC Science & Technology

    1994-03-01

    Guided Missile Destroyer ( DDG - 993 ), and the Guided Missile Cruiser (CG-47) class ships. (Commander, Naval Sea Systems Command, 1985, p. 1-1) The 5" 54 MK...Mod 0 gun system since its introduction. One, in October 1972 aboard the USS NORTON SOUND (AVM-l), that proved the Mod 0 conceptual design was sound...times listed below. iNMI MANZE MIIlION TYPE AND TIME IN 8ECOND USS STUMP 643 667 337 USS GETTYSBURC 423 842 332 Usf o;:scOm 349 633 329 USS HIUE CITY

  3. Reliability Modeling of Microelectromechanical Systems Using Neural Networks

    NASA Technical Reports Server (NTRS)

    Perera. J. Sebastian

    2000-01-01

    Microelectromechanical systems (MEMS) are a broad and rapidly expanding field that is currently receiving a great deal of attention because of the potential to significantly improve the ability to sense, analyze, and control a variety of processes, such as heating and ventilation systems, automobiles, medicine, aeronautical flight, military surveillance, weather forecasting, and space exploration. MEMS are very small and are a blend of electrical and mechanical components, with electrical and mechanical systems on one chip. This research establishes reliability estimation and prediction for MEMS devices at the conceptual design phase using neural networks. At the conceptual design phase, before devices are built and tested, traditional methods of quantifying reliability are inadequate because the device is not in existence and cannot be tested to establish the reliability distributions. A novel approach using neural networks is created to predict the overall reliability of a MEMS device based on its components and each component's attributes. The methodology begins with collecting attribute data (fabrication process, physical specifications, operating environment, property characteristics, packaging, etc.) and reliability data for many types of microengines. The data are partitioned into training data (the majority) and validation data (the remainder). A neural network is applied to the training data (both attribute and reliability); the attributes become the system inputs and reliability data (cycles to failure), the system output. After the neural network is trained with sufficient data. the validation data are used to verify the neural networks provided accurate reliability estimates. Now, the reliability of a new proposed MEMS device can be estimated by using the appropriate trained neural networks developed in this work.

  4. Final Report for the Virtual Reliability Realization System LDRD

    SciTech Connect

    DELLIN, THEODORE A.; HENDERSON, CHRISTOPHER L.; O'TOOLE, EDWARD J.

    2000-12-01

    Current approaches to reliability are not adequate to keep pace with the need for faster, better and cheaper products and systems. This is especially true in high consequence of failure applications. The original proposal for the LDRD was to look at this challenge and see if there was a new paradigm that could make reliability predictions, along with a quantitative estimate of the risk in that prediction, in a way that was faster, better and cheaper. Such an approach would be based on the underlying science models that are the backbone of reliability predictions. The new paradigm would be implemented in two software tools: the Virtual Reliability Realization System (VRRS) and the Reliability Expert System (REX). The three-year LDRD was funded at a reduced level for the first year ($120K vs. $250K) and not renewed. Because of the reduced funding, we concentrated on the initial development of the expertise system. We developed an interactive semiconductor calculation tool needed for reliability analyses. We also were able to generate a basic functional system using Microsoft Siteserver Commerce Edition and Microsoft Sequel Server. The base system has the capability to store Office documents from multiple authors, and has the ability to track and charge for usage. The full outline of the knowledge model has been incorporated as well as examples of various types of content.

  5. Operator adaptation to changes in system reliability under adaptable automation.

    PubMed

    Chavaillaz, Alain; Sauer, Juergen

    2016-11-25

    This experiment examined how operators coped with a change in system reliability between training and testing. Forty participants were trained for 3 h on a complex process control simulation modelling six levels of automation (LOA). In training, participants either experienced a high- (100%) or low-reliability system (50%). The impact of training experience on operator behaviour was examined during a 2.5 h testing session, in which participants either experienced a high- (100%) or low-reliability system (60%). The results showed that most operators did not often switch between LOA. Most chose an LOA that relieved them of most tasks but maintained their decision authority. Training experience did not have a strong impact on the outcome measures (e.g. performance, complacency). Low system reliability led to decreased performance and self-confidence. Furthermore, complacency was observed under high system reliability. Overall, the findings suggest benefits of adaptable automation because it accommodates different operator preferences for LOA. Practitioner Summary: The present research shows that operators can adapt to changes in system reliability between training and testing sessions. Furthermore, it provides evidence that each operator has his/her preferred automation level. Since this preference varies strongly between operators, adaptable automation seems to be suitable to accommodate these large differences.

  6. Assuring long-term reliability of concentrator PV systems

    NASA Astrophysics Data System (ADS)

    McConnell, R.; Garboushian, V.; Brown, J.; Crawford, C.; Darban, K.; Dutra, D.; Geer, S.; Ghassemian, V.; Gordon, R.; Kinsey, G.; Stone, K.; Turner, G.

    2009-08-01

    Concentrator PV (CPV) systems have attracted significant interest because these systems incorporate the world's highest efficiency solar cells and they are targeting the lowest cost production of solar electricity for the world's utility markets. Because these systems are just entering solar markets, manufacturers and customers need to assure their reliability for many years of operation. There are three general approaches for assuring CPV reliability: 1) field testing and development over many years leading to improved product designs, 2) testing to internationally accepted qualification standards (especially for new products) and 3) extended reliability tests to identify critical weaknesses in a new component or design. Amonix has been a pioneer in all three of these approaches. Amonix has an internal library of field failure data spanning over 15 years that serves as the basis for its seven generations of CPV systems. An Amonix product served as the test CPV module for the development of the world's first qualification standard completed in March 2001. Amonix staff has served on international standards development committees, such as the International Electrotechnical Commission (IEC), in support of developing CPV standards needed in today's rapidly expanding solar markets. Recently Amonix employed extended reliability test procedures to assure reliability of multijunction solar cell operation in its seventh generation high concentration PV system. This paper will discuss how these three approaches have all contributed to assuring reliability of the Amonix systems.

  7. Distribution System Reliability Analysis for Smart Grid Applications

    NASA Astrophysics Data System (ADS)

    Aljohani, Tawfiq Masad

    Reliability of power systems is a key aspect in modern power system planning, design, and operation. The ascendance of the smart grid concept has provided high hopes of developing an intelligent network that is capable of being a self-healing grid, offering the ability to overcome the interruption problems that face the utility and cost it tens of millions in repair and loss. To address its reliability concerns, the power utilities and interested parties have spent extensive amount of time and effort to analyze and study the reliability of the generation and transmission sectors of the power grid. Only recently has attention shifted to be focused on improving the reliability of the distribution network, the connection joint between the power providers and the consumers where most of the electricity problems occur. In this work, we will examine the effect of the smart grid applications in improving the reliability of the power distribution networks. The test system used in conducting this thesis is the IEEE 34 node test feeder, released in 2003 by the Distribution System Analysis Subcommittee of the IEEE Power Engineering Society. The objective is to analyze the feeder for the optimal placement of the automatic switching devices and quantify their proper installation based on the performance of the distribution system. The measures will be the changes in the reliability system indices including SAIDI, SAIFI, and EUE. The goal is to design and simulate the effect of the installation of the Distributed Generators (DGs) on the utility's distribution system and measure the potential improvement of its reliability. The software used in this work is DISREL, which is intelligent power distribution software that is developed by General Reliability Co.

  8. Software Technology for Adaptable, Reliable Systems (STARS)

    DTIC Science & Technology

    1990-11-02

    through the use of a single intermediate language. However, certain evolutionary paths, i.e., translators and funtional interfaces, must be established...Systems Ada compiler beginning in December 1984 and was presented at an Arcadia consortium meeting held in December 1984. Iris concepts and a grammar ...Page 11 2 November 1990 STARS-RC-01430/001/00 o An LALR parser generator and an Ada grammar , used to produce the parse phase of the Ada-to-DIANA

  9. Reliability Model Generator for fault-tolerant systems

    NASA Technical Reports Server (NTRS)

    Mccann, Catherine M.; Palumbo, Daniel L.

    1988-01-01

    An analysis tool that reasons from structural and functional system design specifications to generate a reliability model for the system under investigation is presented. The resultant model defines a system state space sufficient to characterize the effects of single and multiple component failures, and the model may then be examined using the Semi-Markov Unreliability Range Evaluator to compute numerical bounds for system reliability. A separation of the component functions from the structural specifications allows easy modification for analysis of alternative architectures. The use of a hierarchical system description paradigm promotes multiple abstractions.

  10. System reliability, performance and trust in adaptable automation.

    PubMed

    Chavaillaz, Alain; Wastell, David; Sauer, Jürgen

    2016-01-01

    The present study examined the effects of reduced system reliability on operator performance and automation management in an adaptable automation environment. 39 operators were randomly assigned to one of three experimental groups: low (60%), medium (80%), and high (100%) reliability of automation support. The support system provided five incremental levels of automation which operators could freely select according to their needs. After 3 h of training on a simulated process control task (AutoCAMS) in which the automation worked infallibly, operator performance and automation management were measured during a 2.5-h testing session. Trust and workload were also assessed through questionnaires. Results showed that although reduced system reliability resulted in lower levels of trust towards automation, there were no corresponding differences in the operators' reliance on automation. While operators showed overall a noteworthy ability to cope with automation failure, there were, however, decrements in diagnostic speed and prospective memory with lower reliability.

  11. Reliability analysis framework for computer-assisted medical decision systems

    SciTech Connect

    Habas, Piotr A.; Zurada, Jacek M.; Elmaghraby, Adel S.; Tourassi, Georgia D.

    2007-02-15

    We present a technique that enhances computer-assisted decision (CAD) systems with the ability to assess the reliability of each individual decision they make. Reliability assessment is achieved by measuring the accuracy of a CAD system with known cases similar to the one in question. The proposed technique analyzes the feature space neighborhood of the query case to dynamically select an input-dependent set of known cases relevant to the query. This set is used to assess the local (query-specific) accuracy of the CAD system. The estimated local accuracy is utilized as a reliability measure of the CAD response to the query case. The underlying hypothesis of the study is that CAD decisions with higher reliability are more accurate. The above hypothesis was tested using a mammographic database of 1337 regions of interest (ROIs) with biopsy-proven ground truth (681 with masses, 656 with normal parenchyma). Three types of decision models, (i) a back-propagation neural network (BPNN), (ii) a generalized regression neural network (GRNN), and (iii) a support vector machine (SVM), were developed to detect masses based on eight morphological features automatically extracted from each ROI. The performance of all decision models was evaluated using the Receiver Operating Characteristic (ROC) analysis. The study showed that the proposed reliability measure is a strong predictor of the CAD system's case-specific accuracy. Specifically, the ROC area index for CAD predictions with high reliability was significantly better than for those with low reliability values. This result was consistent across all decision models investigated in the study. The proposed case-specific reliability analysis technique could be used to alert the CAD user when an opinion that is unlikely to be reliable is offered. The technique can be easily deployed in the clinical environment because it is applicable with a wide range of classifiers regardless of their structure and it requires neither additional

  12. SOFC Systems with Improved Reliability and Endurance

    SciTech Connect

    Ghezel-Ayagh, Hossein

    2015-12-31

    The overall goal of this U.S. Department of Energy (DOE) sponsored project was the development of Solid Oxide Fuel Cell (SOFC) technology suitable for ultra-efficient central power generation systems utilizing coal and natural gas fuels and featuring greater than 90% carbon dioxide capture. The specific technical objective of this project was to demonstrate, via analyses and testing, progress towards adequate stack life (≥ 4 years) and stack performance stability (degradation rate ≤ 0.2% per 1000 hours) in a low-cost SOFC stack design. This final technical report summarizes the progress made during the project period of 27 months. Significant progress was made in the areas of cell and stack technology development, stack module development, sub-scale module tests, and Proof-of-Concept Module unit design, fabrication and testing. The work focused on cell and stack materials and designs, balance-of-plant improvements, and performance evaluation covering operating conditions and fuel compositions anticipated for commercially-deployed systems. In support of performance evaluation under commercial conditions, this work included the design, fabrication, siting, commissioning, and operation of a ≥ 50 kWe proof-of-concept module (PCM) power plant, based upon SOFC cell and stack technology developed to date by FuelCell Energy, Inc. (FCE) under the Office of Fossil Energy’s Solid Oxide Fuel Cells program. The PCM system was operated for at least 1000 hours on natural gas fuel at FCE’s facility. The factory cost of the SOFC stack was estimated to be at or below the DOE’s high-volume production cost target (2011 $).

  13. Seismic reliability assessment of electric power systems

    SciTech Connect

    Singhal, A.; Bouabid, J.

    1995-12-31

    This paper presents a methodology for the seismic risk assessment of electric power systems. In evaluating damage and loss of functionality to the electric power components, fragility curves and restoration functions are used. These vulnerability parameters are extracted from the GIS-based regional loss estimation methodology being developed for the US. Observed damage in electric power components during the Northridge earthquake is used to benchmark the methodology. The damage predicted using these vulnerability parameters is found to be in good agreement with the damage observed during the earthquake.

  14. Advanced Reconnaissance System Component Reliability Study

    DTIC Science & Technology

    1956-07-31

    Test at 0°C -4-5 Room Temperature Test, RCA Cell 4-20 4-6 Roam Temperature Test, Yardney Cell No.2 4-21 ( First Cycle) 4-7 Room Temperature Test...system failures are specified by a negative exponential probability distribution. 1 For example the first entry in the table for an early test vehicle... first vehicle. For this reason con- siderable effort has been placed on determining some of the operating characteristics of batteries. 2. Interim

  15. Feedwater heater life optimization at Peach Bottom Atomic Power Station

    SciTech Connect

    Thomas, D.S.; Catapano, M.C.

    1996-08-01

    This paper illustrates a complete inspection, testing, and maintenance program implemented at PECO Energy`s Peach Bottom Atomic Power Station (PBAPS). Concerns that tubes may have been too conservatively plugged due to insufficient data justified a program that included: removal of previously installed plugs; videoprobe inspection of failed areas; extraction of tube samples for further analysis; eddy current testing of selected tubes; evaluation of the condition of insurance plugged tubes for return to service; hydrostatic testing of selected tubes; final repair plan based on the results of the above program. This paper concludes that no single method of inspection or testing should be solely relied upon in establishing: the extent of actual degraded conditions; the source(s) of failure mechanisms; and the details of repair. It is a combination of all gathered data that affords the best chance in arresting problems and optimizing feedwater heater life.

  16. Reliable regulation in decentralised control systems

    NASA Astrophysics Data System (ADS)

    Locatelli, Arturo; Schiavoni, Nicola

    2011-03-01

    This article addresses the design of decentralised regulators which supply the control systems with signal tracking and disturbance rejection. This property has to be attained, to the maximum possible extent, even when instrumentation faults occur, thus causing the opening of some feedback loops. The problem is tackled for LTI asymptotically stable plants, subject to perturbations, under the assumption that the Laplace transforms of the exogenous signals have multiple poles on the imaginary axis. The proposed regulator is composed of an LTI nominal controller supervised by a reconfiguration block. Once the actions of the reconfiguration block have been settled, the synthesis of the nominal controller is reformulated as a suitable regulation problem. A constructive sufficient condition for its solvability is established. This condition turns out to be also necessary if the exogenous signals are polynomial in time.

  17. UPT scenarios: Implications for system reliability

    NASA Technical Reports Server (NTRS)

    Walsh, Daniel W.

    1992-01-01

    The objective of this project was to examine the corrosion resistance of 316L stainless steel in several urine pre-treat solutions. Four solutions were examined: untreated urine (control); urine pretreated with oxone (potassium peroxymonosulfate sulfate); urine pretreated with sodium hypochlorite (NaOCl); and urine pretreated with ozone (O3). In accordance with current procedures, all solutions but the control were acidified to a pH of 2.5 using sulfuric acid--this suppresses the generation of ammonia in the solutions and is intended to limit microbial growth. Welded and unwelded coupons were exposed to each solution. In addition, Titanium coupons (welded and unwelded) were exposed to biologically active environmental control and life support system (ECLSS) water. Microbial attachment and biofilm growth were monitored. Ozone was examined as a biocide/oxidizer/corrosion preventative (simultaneous addition) and as a remediation method (added one week after exposure). In an unrelated effort, HP 9-4-30 coupons were exposed to biologically active solutions. Corrosion rates for welded and unwelded samples were determined--results were correlated to the ongoing HP 9-4-30 weldment stress corrosion study.

  18. UPT scenarios: Implications for system reliability

    NASA Astrophysics Data System (ADS)

    Walsh, Daniel W.

    1992-12-01

    The objective of this project was to examine the corrosion resistance of 316L stainless steel in several urine pre-treat solutions. Four solutions were examined: untreated urine (control); urine pretreated with oxone (potassium peroxymonosulfate sulfate); urine pretreated with sodium hypochlorite (NaOCl); and urine pretreated with ozone (O3). In accordance with current procedures, all solutions but the control were acidified to a pH of 2.5 using sulfuric acid--this suppresses the generation of ammonia in the solutions and is intended to limit microbial growth. Welded and unwelded coupons were exposed to each solution. In addition, Titanium coupons (welded and unwelded) were exposed to biologically active environmental control and life support system (ECLSS) water. Microbial attachment and biofilm growth were monitored. Ozone was examined as a biocide/oxidizer/corrosion preventative (simultaneous addition) and as a remediation method (added one week after exposure). In an unrelated effort, HP 9-4-30 coupons were exposed to biologically active solutions. Corrosion rates for welded and unwelded samples were determined--results were correlated to the ongoing HP 9-4-30 weldment stress corrosion study.

  19. Dynamic characteristics of a VK-50 reactor operating under conditions of the loss of a normal feedwater flow

    NASA Astrophysics Data System (ADS)

    Semidotskiy, I. I.; Kurskiy, A. S.

    2013-12-01

    The paper describes the conditions of the ATWS type with virtually complete cessation of the feed-water flow at the operating power level of a reactor of the VK-50 type. Under these conditions, the role of spatial kinetics in the system of feedback between thermohydraulic and nuclear processes with bulk boiling of the coolant in the reactor core is clearly seen. This feature determines the specific character of experimental data obtained and the suitability of their use for verification of the associated codes used for calculating water-water reactors.

  20. Survey of Software Assurance Techniques for Highly Reliable Systems

    NASA Technical Reports Server (NTRS)

    Nelson, Stacy

    2004-01-01

    This document provides a survey of software assurance techniques for highly reliable systems including a discussion of relevant safety standards for various industries in the United States and Europe, as well as examples of methods used during software development projects. It contains one section for each industry surveyed: Aerospace, Defense, Nuclear Power, Medical Devices and Transportation. Each section provides an overview of applicable standards and examples of a mission or software development project, software assurance techniques used and reliability achieved.

  1. The Challenges of Credible Thermal Protection System Reliability Quantification

    NASA Technical Reports Server (NTRS)

    Green, Lawrence L.

    2013-01-01

    The paper discusses several of the challenges associated with developing a credible reliability estimate for a human-rated crew capsule thermal protection system. The process of developing such a credible estimate is subject to the quantification, modeling and propagation of numerous uncertainties within a probabilistic analysis. The development of specific investment recommendations, to improve the reliability prediction, among various potential testing and programmatic options is then accomplished through Bayesian analysis.

  2. 46 CFR 52.25-3 - Feedwater heaters (modifies PFH-1).

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... BOILERS Other Boiler Types § 52.25-3 Feedwater heaters (modifies PFH-1). In addition to the requirements in PFH-1 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

  3. 46 CFR 52.25-3 - Feedwater heaters (modifies PFH-1).

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... BOILERS Other Boiler Types § 52.25-3 Feedwater heaters (modifies PFH-1). In addition to the requirements in PFH-1 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

  4. 46 CFR 52.25-3 - Feedwater heaters (modifies PFH-1).

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... BOILERS Other Boiler Types § 52.25-3 Feedwater heaters (modifies PFH-1). In addition to the requirements in PFH-1 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

  5. 46 CFR 52.25-3 - Feedwater heaters (modifies PFH-1).

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... BOILERS Other Boiler Types § 52.25-3 Feedwater heaters (modifies PFH-1). In addition to the requirements in PFH-1 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

  6. 46 CFR 52.25-3 - Feedwater heaters (modifies PFH-1).

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... BOILERS Other Boiler Types § 52.25-3 Feedwater heaters (modifies PFH-1). In addition to the requirements in PFH-1 of section I of the ASME Boiler and Pressure Vessel Code (incorporated by reference; see...

  7. A semi-Markov reliability analysis of alternating systems

    SciTech Connect

    Lee, Kwang Nam; Cho, Nam Zin

    1989-01-01

    Current nuclear power plants must be highly reliable with respect to safety and economy. Consequently, development of a new safety evaluation methodology is desired for the accurate evaluation of safety and economy. A nuclear power plant consists of many systems. This paper is concerned with the reliability evaluation of alternating systems. An alternating system usually consists of multitrains, and its operation alternates from one train to another. Examples of these are the nuclear service cooling water system, the component cooling water system, and the chemical and volume control system. The alternating systems exhibit strong dynamic time-dependent reliability characteristics because of the alternating operational mode and the technical specification requirements that are particularly difficult to analyze by static fault-tree techniques. The method used in this paper is based on the semi-Markov reliability analysis. The system performance measures evaluated are its contribution to the total risk of the plant (e.g., core damage probability) and to plant unavailability (reactor downtime). It is concluded that the methodology developed in this study can be applied to existing alternating systems for plant-specific evaluation of the various alternatives in technical specifications.

  8. Reliability assessment for components of large scale photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Ahadi, Amir; Ghadimi, Noradin; Mirabbasi, Davar

    2014-10-01

    Photovoltaic (PV) systems have significantly shifted from independent power generation systems to a large-scale grid-connected generation systems in recent years. The power output of PV systems is affected by the reliability of various components in the system. This study proposes an analytical approach to evaluate the reliability of large-scale, grid-connected PV systems. The fault tree method with an exponential probability distribution function is used to analyze the components of large-scale PV systems. The system is considered in the various sequential and parallel fault combinations in order to find all realistic ways in which the top or undesired events can occur. Additionally, it can identify areas that the planned maintenance should focus on. By monitoring the critical components of a PV system, it is possible not only to improve the reliability of the system, but also to optimize the maintenance costs. The latter is achieved by informing the operators about the system component's status. This approach can be used to ensure secure operation of the system by its flexibility in monitoring system applications. The implementation demonstrates that the proposed method is effective and efficient and can conveniently incorporate more system maintenance plans and diagnostic strategies.

  9. Inter-Rater Reliability of an Electronic Discussion Coding System.

    ERIC Educational Resources Information Center

    MacKinnon, Gregory R.

    A "cognote" system was developed for coding electronic discussion groups and promoting critical thinking. Previous literature has provided an account of the strategy as applied to several academic settings. This paper addresses the research around establishing the inter-rater reliability of the cognote system. The findings suggest three indicators…

  10. Improving Reliability and Durability of Efficient and Clean Energy Systems

    SciTech Connect

    Singh, Prabhakar

    2010-08-01

    Overall objective of the research program was to develop an in-depth understanding of the degradation processes in advanced electrochemical energy conversion systems. It was also the objective of the research program to transfer the technology to participating industries for implementation in manufacturing of cost effective and reliable integrated systems.

  11. Long life high reliability thermal control systems study data handbook

    NASA Technical Reports Server (NTRS)

    Scollon, T. R., Jr.; Carpitella, M. J.

    1971-01-01

    The development of thermal control systems with high reliability and long service life is discussed. Various passive and semi-active thermal control systems which have been installed on space vehicles are described. The properties of the various coatings are presented in tabular form.

  12. Reliability analysis for LEB ring magnet power system in SSC

    SciTech Connect

    Smedley, K.

    1991-11-01

    The LEB ring magnet power system contains six subsystems, supervisory control, power supplies, regulation, DC bus, resonant cells, and fault sensing network. The system availability of the total LEB RMPS is required to be 0.999. The work in this paper is to allocate the overall LEB RMPS reliability requirement into reliability requirements for each of the subsystems and lower-tier items. The Feasibility-of-Objective technique combining with engineering experience is the key for the allocation. MIL-HDBK-217F is used to derate SCR components. 7 refs., 5 figs.

  13. Laboratory information management system chain of custody: reliability and security.

    PubMed

    Tomlinson, J J; Elliott-Smith, W; Radosta, T

    2006-01-01

    A chain of custody (COC) is required in many laboratories that handle forensics, drugs of abuse, environmental, clinical, and DNA testing, as well as other laboratories that want to assure reliability of reported results. Maintaining a dependable COC can be laborious, but with the recent establishment of the criteria for electronic records and signatures by US regulatory agencies, laboratory information management systems (LIMSs) are now being developed to fully automate COCs. The extent of automation and of data reliability can vary, and FDA- and EPA-compliant electronic signatures and system security are rare.

  14. Laboratory Information Management System Chain of Custody: Reliability and Security

    PubMed Central

    Tomlinson, J. J.; Elliott-Smith, W.; Radosta, T.

    2006-01-01

    A chain of custody (COC) is required in many laboratories that handle forensics, drugs of abuse, environmental, clinical, and DNA testing, as well as other laboratories that want to assure reliability of reported results. Maintaining a dependable COC can be laborious, but with the recent establishment of the criteria for electronic records and signatures by US regulatory agencies, laboratory information management systems (LIMSs) are now being developed to fully automate COCs. The extent of automation and of data reliability can vary, and FDA- and EPA-compliant electronic signatures and system security are rare. PMID:17671623

  15. Reliability modeling and evaluation of HVDC power transmission systems

    SciTech Connect

    Dialynas, E.N.; Koskolos, N.C. . Dept. of Electrical and Computer Engineering)

    1994-04-01

    The objective of this paper is to present an improved computational method for evaluating the reliability indices of HVdc transmission systems. The developed models and computational techniques are described. These can be used to simulate the operational practices and characteristics of a system under study efficiently and realistically. This method is based on the failure modes and effects analysis and uses the event tree method and the minimal cut set approach to represent the system's operational behavior and deduce the appropriate system's failure modes. A set of five reliability indices is evaluated for each output node being analyzed together with the probability and frequency of encountering particular regions of system performance levels. The analysis of an assumed HVdc bipolar transmission system is also included.

  16. The Development of a Demonstration Passive System Reliability Assessment

    SciTech Connect

    Bucknor, Matthew; Grabaskas, David; Brunett, Acacia

    2014-06-22

    In this paper, the details of the development of a demonstration problem to assess the reliability of a passive safety system are presented. An advanced small modular reactor (advSMR) design, which is a pool-type sodium fast reactor (SFR) coupled with a passive reactor cavity cooling system (RCCS) is described. The RELAP5-3D models of the advSMR and RCCS that will be used to simulate a long-term station blackout (SBO) accident scenario are presented. Proposed benchmarking techniques for both the reactor and the RCCS are discussed, which includes utilization of experimental results from the Natural convection Shutdown heat removal Test Facility (NSTF) at the Argonne National Laboratory. Details of how mechanistic methods, specifically the Reliability Method for Passive Systems (RMPS) approach, will be utilized to determine passive system reliability are presented. The results of this mechanistic analysis will ultimately be compared to results from dynamic methods in future work. This work is part of an ongoing project at Argonne to demonstrate methodologies for assessing passive system reliability.

  17. Automated Energy Distribution and Reliability System Status Report

    SciTech Connect

    Buche, D. L.; Perry, S.

    2007-10-01

    This report describes Northern Indiana Public Service Co. project efforts to develop an automated energy distribution and reliability system. The purpose of this project was to implement a database-driven GIS solution that would manage all of the company's gas, electric, and landbase objects.

  18. The Modified Cognitive Constructions Coding System: Reliability and Validity Assessments

    ERIC Educational Resources Information Center

    Moran, Galia S.; Diamond, Gary M.

    2006-01-01

    The cognitive constructions coding system (CCCS) was designed for coding client's expressed problem constructions on four dimensions: intrapersonal-interpersonal, internal-external, responsible-not responsible, and linear-circular. This study introduces, and examines the reliability and validity of, a modified version of the CCCS--a version that…

  19. Automated Energy Distribution and Reliability System (AEDR): Final Report

    SciTech Connect

    Buche, D. L.

    2008-07-01

    This report describes Northern Indiana Public Service Co. project efforts to develop an automated energy distribution and reliability system. The purpose of this project was to implement a database-driven GIS solution that would manage all of the company's gas, electric, and landbase objects.

  20. 75 FR 72664 - System Personnel Training Reliability Standards

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

    ... Energy Regulatory Commission 18 CFR Part 40 System Personnel Training Reliability Standards Issued... section 215 of the Federal Power Act, the Commission approves two Personnel Performance, Training and... Personnel Training), submitted to the Commission for approval by the North American Electric...

  1. Modular reliability modeling of the TJNAF personnel safety system

    SciTech Connect

    Cinnamon, J.; Mahoney, K.

    1997-08-01

    A reliability model for the Thomas Jefferson National Accelerator Facility (formerly CEBAF) personnel safety system has been developed. The model, which was implemented using an Excel spreadsheet, allows simulation of all or parts of the system. Modularity of the model's implementation allows rapid {open_quotes}what if{open_quotes} case studies to simulate change in safety system parameters such as redundancy, diversity, and failure rates. Particular emphasis is given to the prediction of failure modes which would result in the failure of both of the redundant safety interlock systems. In addition to the calculation of the predicted reliability of the safety system, the model also calculates availability of the same system. Such calculations allow the user to make tradeoff studies between reliability and availability, and to target resources to improving those parts of the system which would most benefit from redesign or upgrade. The model includes calculated, manufacturer's data, and Jefferson Lab field data. This paper describes the model, methods used, and comparison of calculated to actual data for the Jefferson Lab personnel safety system. Examples are given to illustrate the model's utility and ease of use.

  2. Modular reliability modeling of the TJNAF personnel safety system

    SciTech Connect

    Cinnamon, J.; Mahoney, K.

    1997-08-01

    A reliability model for the Thomas Jefferson National Accelerator Facility (formerly CEBAF) personnel safety system has been developed. The model, which was implemented using an Excel spreadsheet, allows simulation of all or parts of the system. Modularity os the model`s implementation allows rapid {open_quotes}what if{open_quotes} case studies to simulate change in safety system parameters such as redundancy, diversity, and failure rates. Particular emphasis is given to the prediction of failure modes which would result in the failure of both of the redundant safety interlock systems. In addition to the calculation of the predicted reliability of the safety system, the model also calculates availability of the same system. Such calculations allow the user to make tradeoff studies between reliability and availability, and to target resources to improving those parts of the system which would most benefit from redesign or upgrade. The model includes calculated, manufacturer`s data, and Jefferson Lab field data. This paper describes the model, methods used, and comparison of calculated to actual data for the Jefferson Lab personnel safety system. Examples are given to illustrate the model`s utility and ease of use.

  3. Reliability program requirements for Space and Terrestrial Nuclear Power Systems

    SciTech Connect

    Not Available

    1982-10-01

    The objectives of the reliability program requirements described in this report are (1) to provide contractors with an outline of the reliability requirements established by the Department of Energy (DOE) in the areas of design, development, production, testing, and acceptance of space and terrestrial nuclear systems hardware, and (2) to guide the contractor in meeting these requirements. This publication or particular portions of it is applicable as specified in the contract. Whether the contractors/subcontractors are subject to all the requirements or only to part of them will be specified by contract, program letter, or by the contract statement-of-work.

  4. An integrated approach to system design, reliability, and diagnosis

    NASA Technical Reports Server (NTRS)

    Patterson-Hine, F. A.; Iverson, David L.

    1990-01-01

    The requirement for ultradependability of computer systems in future avionics and space applications necessitates a top-down, integrated systems engineering approach for design, implementation, testing, and operation. The functional analyses of hardware and software systems must be combined by models that are flexible enough to represent their interactions and behavior. The information contained in these models must be accessible throughout all phases of the system life cycle in order to maintain consistency and accuracy in design and operational decisions. One approach being taken by researchers at Ames Research Center is the creation of an object-oriented environment that integrates information about system components required in the reliability evaluation with behavioral information useful for diagnostic algorithms. Procedures have been developed at Ames that perform reliability evaluations during design and failure diagnoses during system operation. These procedures utilize information from a central source, structured as object-oriented fault trees. Fault trees were selected because they are a flexible model widely used in aerospace applications and because they give a concise, structured representation of system behavior. The utility of this integrated environment for aerospace applications in light of our experiences during its development and use is described. The techniques for reliability evaluation and failure diagnosis are discussed, and current extensions of the environment and areas requiring further development are summarized.

  5. Software safety and reliability issues in safety-related systems

    SciTech Connect

    Zucconi, L.

    1992-09-01

    The increasing number of accidents attributed to computer-based systems is causing increased public awareness of the risk associated with these systems' use in safety-related applications. Examples include the Therac-25 medical LINAC deaths, the growing number of Airbus A320 crashes, the AT T Long-Lines disaster on Martin Luther King Day in 1990, the spate of regional telephone outages of the summer of 1991, and many more. How do safety and reliability sometimes conflict What practical computer system and software development technologies and processes can be applied to increase the safety and reliability of computer systems What are the technical and managerial issues contributing to the construction of less-than-safe computer-based systems How can systems engineers and software engineers work together. to address the issues related to safety and reliability of computer systems This paper will address these topics and include an assessment of the best current state-of-the-practice and upcoming technologies that will carry us into the 21st century.

  6. Safety and reliability issues in safety-related systems

    SciTech Connect

    Zucconi, L.

    1992-03-20

    The increasing number of accidents attributed to computer-based systems is causing increased public awareness of the risk associated with these systems` use in safety-related applications. Examples include the Therac-25 medical LINAC deaths, the growing number of Airbus A320 crashes, the AT&T Long-Lines disaster on Martin Luther King Day in 1990, the spate of regional telephone outages of the summer of 1991, and many more. How do safety and reliability sometimes conflict? What practical computer system and software development technologies and processes can be applied to increase the safety and reliability of computer systems? What are the technical and managerial issues contributing to the construction of less-than-safe computer-based systems? How can systems engineers and software engineers work together to address the issues related safety and reliability of computer systems? This paper will address these topics and include an assessment of the best current state-of-the-practice and of upcoming technologies that will carry us into the 21st century.

  7. Safety and reliability issues in safety-related systems

    SciTech Connect

    Zucconi, L.

    1992-03-20

    The increasing number of accidents attributed to computer-based systems is causing increased public awareness of the risk associated with these systems' use in safety-related applications. Examples include the Therac-25 medical LINAC deaths, the growing number of Airbus A320 crashes, the AT T Long-Lines disaster on Martin Luther King Day in 1990, the spate of regional telephone outages of the summer of 1991, and many more. How do safety and reliability sometimes conflict What practical computer system and software development technologies and processes can be applied to increase the safety and reliability of computer systems What are the technical and managerial issues contributing to the construction of less-than-safe computer-based systems How can systems engineers and software engineers work together to address the issues related safety and reliability of computer systems This paper will address these topics and include an assessment of the best current state-of-the-practice and of upcoming technologies that will carry us into the 21st century.

  8. Software safety and reliability issues in safety-related systems

    SciTech Connect

    Zucconi, L.

    1992-09-01

    The increasing number of accidents attributed to computer-based systems is causing increased public awareness of the risk associated with these systems` use in safety-related applications. Examples include the Therac-25 medical LINAC deaths, the growing number of Airbus A320 crashes, the AT&T Long-Lines disaster on Martin Luther King Day in 1990, the spate of regional telephone outages of the summer of 1991, and many more. How do safety and reliability sometimes conflict? What practical computer system and software development technologies and processes can be applied to increase the safety and reliability of computer systems? What are the technical and managerial issues contributing to the construction of less-than-safe computer-based systems? How can systems engineers and software engineers work together. to address the issues related to safety and reliability of computer systems? This paper will address these topics and include an assessment of the best current state-of-the-practice and upcoming technologies that will carry us into the 21st century.

  9. The REPAS Study: Reliability Evaluation of Passive Safety Systems

    SciTech Connect

    Ricotti, M.E.; Bianchi, F.; Burgazzi, L.; D'Auria, F.; Galassi, G.

    2002-07-01

    The strategy of approach to the problem moves from the consideration that a passive system should be theoretically more reliable than an active one. In fact it does not need any external input or energy to operate and it relies only upon natural physical laws (e.g. gravity, natural circulation, internally stored energy, etc.) and/or 'intelligent' use of the energy inherently available in the system (e.g. chemical reaction, decay heat, etc.). Nevertheless the passive system may fail its mission not only as a consequence of classical mechanical failure of components, but also for deviation from the expected behaviour, due to physical phenomena mainly related to thermal-hydraulics or due to different boundary and initial conditions. The main sources of physical failure are identified and a probability of occurrence is assigned. The reliability analysis is performed on a passive system which operates in two-phase, natural circulation. The selected system is a loop including a heat source and a heat sink where the condensation occurs. The system behavior under different configurations has been simulated via best-estimate code (Relap5 mod3.2). The results are shown and can be treated in such a way to give qualitative and quantitative information on the system reliability. Main routes of development of the methodology are also depicted. (authors)

  10. Reliability of emergency ac power systems at nuclear power plants

    SciTech Connect

    Battle, R E; Campbell, D J

    1983-07-01

    Reliability of emergency onsite ac power systems at nuclear power plants has been questioned within the Nuclear Regulatory Commission (NRC) because of the number of diesel generator failures reported by nuclear plant licensees and the reactor core damage that could result from diesel failure during an emergency. This report contains the results of a reliability analysis of the onsite ac power system, and it uses the results of a separate analysis of offsite power systems to calculate the expected frequency of station blackout. Included is a design and operating experience review. Eighteen plants representative of typical onsite ac power systems and ten generic designs were selected to be modeled by fault trees. Operating experience data were collected from the NRC files and from nuclear plant licensee responses to a questionnaire sent out for this project.

  11. A reliable architectural style for designing pervasive healthcare systems.

    PubMed

    Rafe, Vahid; Hajvali, Masoumeh

    2014-09-01

    The evolution of wireless communication technologies opened the way to the definition of innovative e-Health systems aimed at providing a continuous and remote support to patients and new instruments to improve the workflow of the medical personnel. Nowadays, pervasive healthcare systems are a major step in this regard. The safety-critical systems on one hand and their failure in communication (i.e. sending and receiving messages) in other hand may lead to disaster results in the systems. Moreover, the need for high quality services in such systems, and the access to various types of Quality of Services such as reliability in software development has been increasing in the past years. In this paper, firstly we extend the core meta-model of the previously designed style for designing the structures of such systems in order to reach a high level of reliability in messaging. Secondly, their configuration mechanisms in controlling the communicative errors will be modeled using graph transformation rules. Finally, the correctness of the model is analyzed by model checking techniques. The results of the analysis show its high reliability.

  12. Practical reliability and uncertainty quantification in complex systems : final report.

    SciTech Connect

    Grace, Matthew D.; Ringland, James T.; Marzouk, Youssef M.; Boggs, Paul T.; Zurn, Rena M.; Diegert, Kathleen V.; Pebay, Philippe Pierre; Red-Horse, John Robert

    2009-09-01

    The purpose of this project was to investigate the use of Bayesian methods for the estimation of the reliability of complex systems. The goals were to find methods for dealing with continuous data, rather than simple pass/fail data; to avoid assumptions of specific probability distributions, especially Gaussian, or normal, distributions; to compute not only an estimate of the reliability of the system, but also a measure of the confidence in that estimate; to develop procedures to address time-dependent or aging aspects in such systems, and to use these models and results to derive optimal testing strategies. The system is assumed to be a system of systems, i.e., a system with discrete components that are themselves systems. Furthermore, the system is 'engineered' in the sense that each node is designed to do something and that we have a mathematical description of that process. In the time-dependent case, the assumption is that we have a general, nonlinear, time-dependent function describing the process. The major results of the project are described in this report. In summary, we developed a sophisticated mathematical framework based on modern probability theory and Bayesian analysis. This framework encompasses all aspects of epistemic uncertainty and easily incorporates steady-state and time-dependent systems. Based on Markov chain, Monte Carlo methods, we devised a computational strategy for general probability density estimation in the steady-state case. This enabled us to compute a distribution of the reliability from which many questions, including confidence, could be addressed. We then extended this to the time domain and implemented procedures to estimate the reliability over time, including the use of the method to predict the reliability at a future time. Finally, we used certain aspects of Bayesian decision analysis to create a novel method for determining an optimal testing strategy, e.g., we can estimate the 'best' location to take the next test to

  13. 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.

  14. Development of distribution system reliability and risk analysis models

    NASA Astrophysics Data System (ADS)

    Vismor, T. D.; Northcote-Green, J. E. D.; Kostyal, S. J.; Brooks, C. L.

    1981-08-01

    The two reliability models, their testing, and the modifications of a unified distribution planning model to calculate reliability indices are described. The historical reliability assessment model HISRAM is designed to suit most utilities. Four implementation levels with different input data requirements and output capabilities permit a utility to select a level appropriate to its needs. User-defined divisions, causes and output options further add to the program flexibility. A unique feature of HISRAM is the program generation of the appropriate outage reporting form following level selection and initialization. This allows the engineer to review data input requirements before field implementation. It has the capability of estimating component failure rates and restoration times upon provision of suitable input data. The predictive reliability assessment model PRAM uses continuity criteria, together with component failure rates and restoration times to calculate load point indices. System indices similar to those produced by HISRAM are also calculated. Varying degrees of detail for representing the protection system are available through three user-selected models. Both models were tested through application. The conclusions and recommendations of the entire project are included.

  15. Composite system reliability evaluation using sequential Monte Carlo simulation

    NASA Astrophysics Data System (ADS)

    Jonnavithula, Annapoorani

    Monte Carlo simulation methods can be effectively used to assess the adequacy of composite power system networks. The sequential simulation approach is the most fundamental technique available and can be used to provide a wide range of indices. It can also be used to provide estimates which can serve as benchmarks against which other approximate techniques can be compared. The focus of this research work is on the reliability evaluation of composite generation and transmission systems with special reference to frequency and duration related indices and estimated power interruption costs at each load bus. One of the main objectives is to use the sequential simulation method to create a comprehensive technique for composite system adequacy evaluation. This thesis recognizes the need for an accurate representation of the load model at the load buses which depends on the mix of customer sectors at each bus. Chronological hourly load curves are developed in this thesis, recognizing the individual load profiles of the customers at each load bus. Reliability worth considerations are playing an ever increasing role in power system planning and operation. Different methods for bus outage cost evaluation are proposed in this thesis. It may not be computationally feasible to use the sequential simulation method with time varying loads at each bus in large electric power system networks. Time varying load data may also not be available at each bus. This research work uses the sequential methodology as a fundamental technique to calibrate other non sequential methods such as the state sampling and state transition sampling techniques. Variance reduction techniques that improve the efficiency of the sequential simulation procedure are investigated as a part of this research work. Pertinent features that influence reliability worth assessment are also incorporated. All the proposed methods in this thesis are illustrated by application to two reliability test systems. In addition

  16. Determination of Turboprop Reduction Gearbox System Fatigue Life and Reliability

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Lewicki, David G.; Savage, Michael; Vlcek, Brian L.

    2007-01-01

    Two computational models to determine the fatigue life and reliability of a commercial turboprop gearbox are compared with each other and with field data. These models are (1) Monte Carlo simulation of randomly selected lives of individual bearings and gears comprising the system and (2) two-parameter Weibull distribution function for bearings and gears comprising the system using strict-series system reliability to combine the calculated individual component lives in the gearbox. The Monte Carlo simulation included the virtual testing of 744,450 gearboxes. Two sets of field data were obtained from 64 gearboxes that were first-run to removal for cause, were refurbished and placed back in service, and then were second-run until removal for cause. A series of equations were empirically developed from the Monte Carlo simulation to determine the statistical variation in predicted life and Weibull slope as a function of the number of gearboxes failed. The resultant L(sub 10) life from the field data was 5,627 hr. From strict-series system reliability, the predicted L(sub 10) life was 774 hr. From the Monte Carlo simulation, the median value for the L(sub 10) gearbox lives equaled 757 hr. Half of the gearbox L(sub 10) lives will be less than this value and the other half more. The resultant L(sub 10) life of the second-run (refurbished) gearboxes was 1,334 hr. The apparent load-life exponent p for the roller bearings is 5.2. Were the bearing lives to be recalculated with a load-life exponent p equal to 5.2, the predicted L(sub 10) life of the gearbox would be equal to the actual life obtained in the field. The component failure distribution of the gearbox from the Monte Carlo simulation was nearly identical to that using the strict-series system reliability analysis, proving the compatibility of these methods.

  17. Distribution and reliability in a multiprocessor operating system

    SciTech Connect

    Sindhu, P.S.

    1984-01-01

    This thesis explores whether distributed hardware can be used to build reliable systems that are practical. It deals mostly with issues in the design and construction of the MEDUSA operating system, built to run of the distributed multiprocessor Cm. The goal is to exploit the redundancy, physical distribution, and powerful communication facilities within Cm to produce a robust system - one that can function satisfactorily in spite of hardware failure, bad data, heavy demands on its services, and other disruptive occurrences. The thesis demonstrates that, given appropriate hardware, it is possible to provide robustness without significantly sacrificing performance or greatly increasing complexity. Factors important to this success were 1) the treatment of reliability as a probabilistic rather than an absolute guarantee, which resulted in a structure whose components explicitly acknowledge and cope with failures in one another; 2) the adoption of a systematic approach to exception processing, which made the complexity of recovery manageable; and 3) the exploitation of system knowledge in the design of reliability mechanisms, which made it possible to achieve robustness while retaining good normal-case performance.

  18. Optimal reliability design method for remote solar systems

    NASA Astrophysics Data System (ADS)

    Suwapaet, Nuchida

    A unique optimal reliability design algorithm is developed for remote communication systems. The algorithm deals with either minimizing an unavailability of the system within a fixed cost or minimizing the cost of the system with an unavailability constraint. The unavailability of the system is a function of three possible failure occurrences: individual component breakdown, solar energy deficiency (loss of load probability), and satellite/radio transmission loss. The three mathematical models of component failure, solar power failure, transmission failure are combined and formulated as a nonlinear programming optimization problem with binary decision variables, such as number and type (or size) of photovoltaic modules, batteries, radios, antennas, and controllers. Three possible failures are identified and integrated in computer algorithm to generate the parameters for the optimization algorithm. The optimization algorithm is implemented with a branch-and-bound technique solution in MS Excel Solver. The algorithm is applied to a case study design for an actual system that will be set up in remote mountainous areas of Peru. The automated algorithm is verified with independent calculations. The optimal results from minimizing the unavailability of the system with the cost constraint case and minimizing the total cost of the system with the unavailability constraint case are consistent with each other. The tradeoff feature in the algorithm allows designers to observe results of 'what-if' scenarios of relaxing constraint bounds, thus obtaining the most benefit from the optimization process. An example of this approach applied to an existing communication system in the Andes shows dramatic improvement in reliability for little increase in cost. The algorithm is a real design tool, unlike other existing simulation design tools. The algorithm should be useful for other stochastic systems where component reliability, random supply and demand, and communication are

  19. Markov reliability models for digital flight control systems

    NASA Technical Reports Server (NTRS)

    Mcgough, John; Reibman, Andrew; Trivedi, Kishor

    1989-01-01

    The reliability of digital flight control systems can often be accurately predicted using Markov chain models. The cost of numerical solution depends on a model's size and stiffness. Acyclic Markov models, a useful special case, are particularly amenable to efficient numerical solution. Even in the general case, instantaneous coverage approximation allows the reduction of some cyclic models to more readily solvable acyclic models. After considering the solution of single-phase models, the discussion is extended to phased-mission models. Phased-mission reliability models are classified based on the state restoration behavior that occurs between mission phases. As an economical approach for the solution of such models, the mean failure rate solution method is introduced. A numerical example is used to show the influence of fault-model parameters and interphase behavior on system unreliability.

  20. Reliability Value of Fast State Estimation on Power Systems

    SciTech Connect

    Elizondo, Marcelo A.; Chen, Yousu; Huang, Zhenyu

    2012-05-07

    Monitoring the state of a power system under stress is key to achieving reliable operation. State estimation and timely measurements become more important when applying and designing corrective control actions (manual and automatic) to arrest or mitigate cascading blackouts. The execution time of each process, including state estimation, should be as short as possible to allow for timely action. In this paper, we provide a methodology for estimating one of the components of value of faster and more frequent state estimation: the reliability value of state estimation to assist corrective control actions for arresting or mitigating cascading blackouts. We present a new algorithm for estimating the time between successive line trips in a cascading failure. The algorithm combines power flow calculations with characteristics of the protection system to estimate the time between successive equipment trips. Using this algorithm, we illustrate the value of fast state estimation by calculating the time remaining for automatic or manual corrective actions after state estimation is finalized.

  1. Reliability Analysis of Penetration Systems Using Nondeterministic Methods

    SciTech Connect

    FIELD JR.,RICHARD V.; PAEZ,THOMAS L.; RED-HORSE,JOHN R.

    1999-10-27

    Device penetration into media such as metal and soil is an application of some engineering interest. Often, these devices contain internal components and it is of paramount importance that all significant components survive the severe environment that accompanies the penetration event. In addition, the system must be robust to perturbations in its operating environment, some of which exhibit behavior which can only be quantified to within some level of uncertainty. In the analysis discussed herein, methods to address the reliability of internal components for a specific application system are discussed. The shock response spectrum (SRS) is utilized in conjunction with the Advanced Mean Value (AMV) and Response Surface methods to make probabilistic statements regarding the predicted reliability of internal components. Monte Carlo simulation methods are also explored.

  2. Reliability of the special support system for sitting pressure redistribution

    PubMed Central

    Lee, Sang-Heon

    2016-01-01

    [Purpose] This study investigated the reliability of the Special Support System. [Subjects and Methods] Eighteen female and 14 male volunteers participated in this study. Participants were asked to sit on the Special Support System with their chins tucked in, spines straight, pelvis neutrally positioned, and their hands placed on their thighs. They were also asked to flex their hips, knees, and ankles to approximately 90 degrees and to put their feet flat on the floor. The total contact area, mean total pressure, as well as mean and peak pressures of each quadrant were each measured 15 times. Test-retest reliability was analyzed for inflated air pressure, and pressure redistribution values by using intraclass correlation coefficients. [Results] The intraclass correlation coefficient was greater than 0.89 for inflated air pressure and greater than 0.92 for total contact area, mean total pressure, and each quadrant’s mean and peak pressure. [Conclusion] The findings suggest that the Special Support System is reliable and can be used as an alternative method for redistributing sitting pressure. PMID:28174458

  3. Reliability Constrained Priority Load Shedding for Aerospace Power System Automation

    NASA Technical Reports Server (NTRS)

    Momoh, James A.; Zhu, Jizhong; Kaddah, Sahar S.; Dolce, James L. (Technical Monitor)

    2000-01-01

    The need for improving load shedding on board the space station is one of the goals of aerospace power system automation. To accelerate the optimum load-shedding functions, several constraints must be involved. These constraints include congestion margin determined by weighted probability contingency, component/system reliability index, generation rescheduling. The impact of different faults and indices for computing reliability were defined before optimization. The optimum load schedule is done based on priority, value and location of loads. An optimization strategy capable of handling discrete decision making, such as Everett optimization, is proposed. We extended Everett method to handle expected congestion margin and reliability index as constraints. To make it effective for real time load dispatch process, a rule-based scheme is presented in the optimization method. It assists in selecting which feeder load to be shed, the location of the load, the value, priority of the load and cost benefit analysis of the load profile is included in the scheme. The scheme is tested using a benchmark NASA system consisting of generators, loads and network.

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

    SciTech Connect

    BEVINS, R.R.

    2000-09-05

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

  5. Comparison Modeling of System Reliability for Future NASA Projects

    NASA Technical Reports Server (NTRS)

    Gillespie, Amanda M.; Monaghan, Mark W.; Chen, Yuan

    2011-01-01

    A National Aeronautics and Space Administration (NASA) supported Reliability, Maintainability, and Availability (RMA) analysis team developed a unique RMA analysis methodology using cut set and importance measure analysis in order to comparison model proposed avionics computing architectures. In this paper we will present this efficient application of the RMA analysis methodology for importance measures that includes Reliability Block Diagram (RED) Analysis, Comparison modeling, Cut Set Analysis, and Importance Measure Analysis. We will also demonstrate that integrating RMA early in the system design process as a key to success by providing a fundamental decision metric supporting design selection. The RMA analysis methodology presented in this paper and applied to the avionics architectures enhances the usual way of predicting the need for redundancy based on failure rates or subject matter expert opinion. Using the REDs and the minimal cut sets, along with the Fussell-Vesely (FV) factors, importance measures are calculated for each functional element in the architectures. This paper presents an application of the FV importance measures and presents an improved methodology for using importance measures in success space (instead of failure space) to compare architectures. These importance measures are used to determine which functional element would be most likely to cause a system failure, thus, quickly identifying the path to increase the overall system reliability by either procuring more reliable functional elements or adding redundancy. This application of the RMA analysis methodology, using RBD analysis, cut set analysis, and the importance measure analysis, allows the avionics design team to better understand and compare the vulnerabilities in each of the architectures, enabling them to address the deficiencies in the design architectures more efficiently, while balancing the need to design for optimum weight and space allocations.

  6. Steam generator feedwater nozzle transition piece replacement experience at Salem Unit 1

    SciTech Connect

    Patten, D.B.; Perrin, J.S.; Roberts, A.T.; Cofie, N.G.; Mattson, R.A.; Amberg, A.A.; Burkhalter, S.M.; Amador, P.E.

    1996-12-01

    Cracking of steam generator feedwater piping adjacent to the feedwater nozzles has been a recurring problem since 1979 at Salem Unit 1 owned and operated by Public Service Electric and Gas Company. In addition to the cracking problem, erosion-corrosion at the leading edge of the feedwater nozzle thermal sleeve was also observed in 1992. To provide a long-term solution for the pipe cracking and thermal sleeve erosion-corrosion problems, a unique transition piece forging was specially designed, fabricated, and installed for each of the four steam generators during the 1995 outage. This paper discusses the design, fabrication, and installation of the transition piece forgings at Salem Unit 1, and the experiences gained from this project. It is believed that these experiences may help other utilities when planning similar replacements in the future.

  7. Summary of Research on Reliability Criteria-Based Flight System Control

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva; Belcastro, Christine (Technical Monitor)

    2002-01-01

    This paper presents research on the reliability assessment of adaptive flight control systems. The topics include: 1) Overview of Project Focuses; 2) Reliability Analysis; and 3) Design for Reliability. This paper is presented in viewgraph form.

  8. Reliability of Fault Tolerant Control Systems. Part 2

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    2000-01-01

    This paper reports Part II of a two part effort that is intended to delineate the relationship between reliability and fault tolerant control in a quantitative manner. Reliability properties peculiar to fault-tolerant control systems are emphasized, such as the presence of analytic redundancy in high proportion, the dependence of failures on control performance, and high risks associated with decisions in redundancy management due to multiple sources of uncertainties and sometimes large processing requirements. As a consequence, coverage of failures through redundancy management can be severely limited. The paper proposes to formulate the fault tolerant control problem as an optimization problem that maximizes coverage of failures through redundancy management. Coverage modeling is attempted in a way that captures its dependence on the control performance and on the diagnostic resolution. Under the proposed redundancy management policy, it is shown that an enhanced overall system reliability can be achieved with a control law of a superior robustness, with an estimator of a higher resolution, and with a control performance requirement of a lesser stringency.

  9. Calculation of Lower Confidence Bounds on System Reliability

    DTIC Science & Technology

    1985-02-01

    by: Si Number of Successes R8 -1- Q .(2 Fj=Number of Failures (2 The equivalent numbers of successes and failures are then Fiue3.Paall drv : syte of...F2 N Q * Component A F + 1 Si. Fi Q1+1 Cornent1 ftf * and the maximum likelihood estimate of the system Ni =Numer f Tsts reliability is then given...component with F failures out of N tests. An example of a parallel system is given in figure 4. The computational steps proceed as follows: 2 1 Step 1. Q 0 X

  10. Reliability-Based Control Design for Uncertain Systems

    NASA Technical Reports Server (NTRS)

    Crespo, Luis G.; Kenny, Sean P.

    2005-01-01

    This paper presents a robust control design methodology for systems with probabilistic parametric uncertainty. Control design is carried out by solving a reliability-based multi-objective optimization problem where the probability of violating design requirements is minimized. Simultaneously, failure domains are optimally enlarged to enable global improvements in the closed-loop performance. To enable an efficient numerical implementation, a hybrid approach for estimating reliability metrics is developed. This approach, which integrates deterministic sampling and asymptotic approximations, greatly reduces the numerical burden associated with complex probabilistic computations without compromising the accuracy of the results. Examples using output-feedback and full-state feedback with state estimation are used to demonstrate the ideas proposed.

  11. Reliability measurement during software development. [for a multisensor tracking system

    NASA Technical Reports Server (NTRS)

    Hecht, H.; Sturm, W. A.; Trattner, S.

    1977-01-01

    During the development of data base software for a multi-sensor tracking system, reliability was measured. The failure ratio and failure rate were found to be consistent measures. Trend lines were established from these measurements that provided good visualization of the progress on the job as a whole as well as on individual modules. Over one-half of the observed failures were due to factors associated with the individual run submission rather than with the code proper. Possible application of these findings for line management, project managers, functional management, and regulatory agencies is discussed. Steps for simplifying the measurement process and for use of these data in predicting operational software reliability are outlined.

  12. An integrated approach to system design, reliability, and diagnosis

    NASA Technical Reports Server (NTRS)

    Patterson-Hine, F. A.; Iverson, David L.

    1990-01-01

    The requirement for ultradependability of computer systems in future avionics and space applications necessitates a top-down, integrated systems ingeneering approach for design, implementation, testing, and operation. The functional analyses of hardware and software systems must be combined by models that are flexible enough to represent their interactions and behavior. The information contained in these models must be accessible throughout all phases of the system life cycle in order to maintain consistency and accuracy in design and operational decisions. One approach being taken by researchers at Ames Research Center is the creation of an object-oriented environment that integrates information about system components required in the reliability evaluation with behavioral information useful for diagnostic algorithms.

  13. Generalized storage-reliability-yield relationships for rainwater harvesting systems

    NASA Astrophysics Data System (ADS)

    Hanson, L. S.; Vogel, R. M.

    2014-07-01

    Sizing storage for rainwater harvesting (RWH) systems is often a difficult design consideration, as the system must be designed specifically for the local rainfall pattern. We introduce a generally applicable method for estimating the required storage by using regional regression equations to account for climatic differences in the behavior of RWH systems across the entire continental United States. A series of simulations for 231 locations with continuous daily precipitation records enable the development of storage-reliability-yield (SRY) relations at four useful reliabilities, 0.8, 0.9, 0.95, and 0.98. Multivariate, log-linear regression results in storage equations that include demand, collection area and local precipitation statistics. The continental regression equations demonstrated excellent goodness-of-fit (R2 0.96-0.99) using only two precipitation parameters, and fits improved when three geographic regions with more homogeneous rainfall characteristics were considered. The SRY models can be used to obtain a preliminary estimate of how large to build a storage tank almost anywhere in the United States based on desired yield and reliability, collection area, and local rainfall statistics. Our methodology could be extended to other regions of world, and the equations presented herein could be used to investigate how RWH systems would respond to changes in climatic variability. The resulting model may also prove useful in regional planning studies to evaluate the net benefits which result from the broad use of RWH to meet water supply requirements. We outline numerous other possible extensions to our work, which when taken together, illustrate the value of our initial generalized SRY model for RWH systems.

  14. Effects of Data Scrubbing on Reliability in Storage Systems

    NASA Astrophysics Data System (ADS)

    Ryu, Junkil; Park, Chanik

    Silent data corruptions, which are induced by latent sector errors, phantom writes, DMA parity errors and so on, can be detected by explicitly issuing a read command to a disk controller and comparing the corresponding data with their checksums. Because some of the data stored in a storage system may not be accessed for a long time, there is a high chance of silent data corruption occurring undetected, resulting in data loss. Therefore, periodic checking of the entire data in a storage system, known as data scrubbing, is essential to detect such silent data corruptions in time. The errors detected by data scrubbing will be recovered by the replica or the redundant information maintained to protect against permanent data loss. The longer the period between data scrubbings, the higher the probability of a permanent data loss. This paper proposes a Markov failure and repair model to conservatively analyze the effect of data scrubbing on the reliability of a storage system. We show the relationship between the period of a data scrubbing operation and the number of data replicas to manage the reliability of a storage system by using the proposed model.

  15. On the reliable decentralised stabilisation of n MIMO systems

    NASA Astrophysics Data System (ADS)

    Befekadu, Getachew K.; Gupta, Vijay; Antsaklis, Panos J.

    2014-08-01

    In this paper, we consider the problem of reliable decentralised stabilisation for n multi-input multi-output (MIMO) systems when some of the shared controllers among these systems are faulty, in the sense that they fail to operate properly due to subsystem (module) failures that may occur in actuators, sensors or controllers. Specifically, we present a design framework using a dilated linear matrix inequalities (LMIs) technique for deriving reliable stabilising state-feedback gains for all n MIMO systems; while a set of decentralised unknown disturbance observers (UDOs) that are shared by all n MIMO systems is used for extending the result to the output-feedback case. Moreover, a sufficient condition for the solvability of the set of decentralised UDOs is given in terms of a minimum-phase condition of each subsystem and a lower-bounding condition on the number of outputs of each channel. We also present a numerical example that illustrates the applicability of the proposed technique.

  16. Efficient reliability-based design of mooring systems

    SciTech Connect

    Larsen, K.

    1996-12-31

    Uncertainties both in the environmentally induced load effects and in the strength of mooring line components make a rational design of mooring systems a complex task. The methods of structural reliability, taking these uncertainties into account, have been applied in an efficient probabilistic analysis procedure for the tension overload limit state for mooring lines. This paper outlines the philosophy and methodology for this procedure, followed by numerical examples of a turret moored ship. Both base case annual failure probabilities and results from a number of sensitivity analyses are presented. It is demonstrated that the reliability-based design procedure can be effectively utilized to quantify the safety against failure due to tension overload of moorings. The results of the case studies indicate that the largest uncertainties are associated with the distribution parameters of the chain link and steel wire rope segment tension capacity, and the modelling of the environment. The modelling of spreading angles between waves, wind and current vs. colinearity, and double-peaked vs. single-peaked wave spectrum models are key parameters in the reliability assessment.

  17. On reliable control system designs. Ph.D. Thesis; [actuators

    NASA Technical Reports Server (NTRS)

    Birdwell, J. D.

    1978-01-01

    A mathematical model for use in the design of reliable multivariable control systems is discussed with special emphasis on actuator failures and necessary actuator redundancy levels. The model consists of a linear time invariant discrete time dynamical system. Configuration changes in the system dynamics are governed by a Markov chain that includes transition probabilities from one configuration state to another. The performance index is a standard quadratic cost functional, over an infinite time interval. The actual system configuration can be deduced with a one step delay. The calculation of the optimal control law requires the solution of a set of highly coupled Riccati-like matrix difference equations. Results can be used for off-line studies relating the open loop dynamics, required performance, actuator mean time to failure, and functional or identical actuator redundancy, with and without feedback gain reconfiguration strategies.

  18. Spaceflight Ground Support Equipment Reliability & System Safety Data

    NASA Technical Reports Server (NTRS)

    Fernandez, Rene; Riddlebaugh, Jeffrey; Brinkman, John; Wilkinson, Myron

    2012-01-01

    Presented were Reliability Analysis, consisting primarily of Failure Modes and Effects Analysis (FMEA), and System Safety Analysis, consisting of Preliminary Hazards Analysis (PHA), performed to ensure that the CoNNeCT (Communications, Navigation, and Networking re- Configurable Testbed) Flight System was safely and reliably operated during its Assembly, Integration and Test (AI&T) phase. A tailored approach to the NASA Ground Support Equipment (GSE) standard, NASA-STD-5005C, involving the application of the appropriate Requirements, S&MA discipline expertise, and a Configuration Management system (to retain a record of the analysis and documentation) were presented. Presented were System Block Diagrams of selected GSE and the corresponding FMEA, as well as the PHAs. Also discussed are the specific examples of the FMEAs and PHAs being used during the AI&T phase to drive modifications to the GSE (via "redlining" of test procedures, and the placement of warning stickers to protect the flight hardware) before being interfaced to the Flight System. These modifications were necessary because failure modes and hazards were identified during the analysis that had not been properly mitigated. Strict Configuration Management was applied to changes (whether due to upgrades or expired calibrations) in the GSE by revisiting the FMEAs and PHAs to reflect the latest System Block Diagrams and Bill Of Material. The CoNNeCT flight system has been successfully assembled, integrated, tested, and shipped to the launch site without incident. This demonstrates that the steps taken to safeguard the flight system when it was interfaced to the various GSE were successful.

  19. Parametric analysis of the reliability of igniter systems - PARIS

    NASA Astrophysics Data System (ADS)

    Leeuw, M. W.; Bal, E. A.; Prinse, W. C.

    1992-06-01

    A fully automated improved thermal transient test set is used to measure the thermoelectrical response of a number of different fuze heads. The fitted wire model is used to describe the heat dynamics in the fuze head and to calculate a number of intrinsic thermal properties. These properties are used as input for a parametric analysis of the reliability of igniter systems (PARIS). Comparison of PARIS with firing levels obtained with the classical Robbins-Monro method has been used to validate this new way to estimate the sensitivity of fuze heads.

  20. Reliability and availability requirements analysis for DEMO: fuel cycle system

    SciTech Connect

    Pinna, T.; Borgognoni, F.

    2015-03-15

    The Demonstration Power Plant (DEMO) will be a fusion reactor prototype designed to demonstrate the capability to produce electrical power in a commercially acceptable way. Two of the key elements of the engineering development of the DEMO reactor are the definitions of reliability and availability requirements (or targets). The availability target for a hypothesized Fuel Cycle has been analysed as a test case. The analysis has been done on the basis of the experience gained in operating existing tokamak fusion reactors and developing the ITER design. Plant Breakdown Structure (PBS) and Functional Breakdown Structure (FBS) related to the DEMO Fuel Cycle and correlations between PBS and FBS have been identified. At first, a set of availability targets has been allocated to the various systems on the basis of their operating, protection and safety functions. 75% and 85% of availability has been allocated to the operating functions of fuelling system and tritium plant respectively. 99% of availability has been allocated to the overall systems in executing their safety functions. The chances of the systems to achieve the allocated targets have then been investigated through a Failure Mode and Effect Analysis and Reliability Block Diagram analysis. The following results have been obtained: 1) the target of 75% for the operations of the fuelling system looks reasonable, while the target of 85% for the operations of the whole tritium plant should be reduced to 80%, even though all the tritium plant systems can individually reach quite high availability targets, over 90% - 95%; 2) all the DEMO Fuel Cycle systems can reach the target of 99% in accomplishing their safety functions. (authors)

  1. HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 2: HARP tutorial

    NASA Technical Reports Server (NTRS)

    Rothmann, Elizabeth; Dugan, Joanne Bechta; Trivedi, Kishor S.; Mittal, Nitin; Bavuso, Salvatore J.

    1994-01-01

    The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. The Hybrid Automated Reliability Predictor (HARP) tutorial provides insight into HARP modeling techniques and the interactive textual prompting input language via a step-by-step explanation and demonstration of HARP's fault occurrence/repair model and the fault/error handling models. Example applications are worked in their entirety and the HARP tabular output data are presented for each. Simple models are presented at first with each succeeding example demonstrating greater modeling power and complexity. This document is not intended to present the theoretical and mathematical basis for HARP.

  2. Methods for reliability evaluation of trust and reputation systems

    NASA Astrophysics Data System (ADS)

    Janiszewski, Marek B.

    2016-09-01

    Trust and reputation systems are a systematic approach to build security on the basis of observations of node's behaviour. Exchange of node's opinions about other nodes is very useful to indicate nodes which act selfishly or maliciously. The idea behind trust and reputation systems gets significance because of the fact that conventional security measures (based on cryptography) are often not sufficient. Trust and reputation systems can be used in various types of networks such as WSN, MANET, P2P and also in e-commerce applications. Trust and reputation systems give not only benefits but also could be a thread itself. Many attacks aim at trust and reputation systems exist, but such attacks still have not gain enough attention of research teams. Moreover, joint effects of many of known attacks have been determined as a very interesting field of research. Lack of an acknowledged methodology of evaluation of trust and reputation systems is a serious problem. This paper aims at presenting various approaches of evaluation such systems. This work also contains a description of generalization of many trust and reputation systems which can be used to evaluate reliability of such systems in the context of preventing various attacks.

  3. Reliability and Maintainability Data for Liquid Metal Cooling Systems

    SciTech Connect

    Cadwallader, Lee Charles

    2015-05-01

    One of the coolants of interest for future fusion breeding blankets is lead-lithium. As a liquid metal it offers the advantages of high temperature operation for good station efficiency, low pressure, and moderate flow rate. This coolant is also under examination for use in test blanket modules to be used in the ITER international project. To perform reliability, availability, maintainability and inspectability (RAMI) assessment as well as probabilistic safety assessment (PSA) of lead-lithium cooling systems, component failure rate data are needed to quantify the system models. RAMI assessment also requires repair time data and inspection time data. This paper presents a new survey of the data sets that are available at present to support RAMI and PSA quantification. Recommendations are given for the best data values to use when quantifying system models.

  4. NLC Reliability Analysis Notes: Klystron-Modulator System (LCC-0029)

    SciTech Connect

    Wilson, Z.

    2004-03-23

    This paper address the reliability and availability issues to be faced in deploying and operating the klystron modulator assemblies proposed for the Next Linear Collider (NLC). The rf power sources are a major system of the NLC and require a high uptime in order to reach the goal of 0.85 availability. Since the NLC is made up of several systems, not just klystron-modulator assemblies, the availability goal for the assemblies must be higher than 0.85. Currently this goal is at least 0.95. This short paper summarizes the analysis currently under way to determine whether the design of the rf power system will meet the design availability goal.

  5. Health and safety management system audit reliability pilot project.

    PubMed

    Dyjack, D T; Redinger, C F; Ridge, R S

    2003-01-01

    This pilot study assessed occupational health and safety (OHS) management system audit finding reliability using a modified test-retest method. Two industrial hygienists with similar training and education conducted four, 1-day management system audits in four dissimilar organizational environments. The researchers examined four auditable sections (employee participation, training, controls, and communications) contained in a publicly available OHS management system assessment instrument. At each site, 102 auditable clauses were evaluated using a progressive 6-point scale. The team examined both the consistency of and agreement between the scores of the two auditors. Consistency was evaluated by calculating the Pearson r correlations for the two auditors' scores at each site and for each section within each site. Pearson correlations comparing overall scores for each site were all very low, ranging from 0.206 to 0.543. Training and communication system assessments correlated the highest, whereas employee participation and control system scores correlated the least. To measure agreement, t-tests were first calculated to determine whether the differences were statistically significant. Aggregate mean scores for two of the four sites were significantly different. Of the 16 total sections evaluated (i.e., 4 sections per site), seven scores were significantly different. Finally, the agreement of the scores between the two auditors for the four sites was evaluated by calculating two types of intraclass correlation coefficients, all of which failed to meet the minimum requirement for agreement. These findings suggest that opportunities for improving the reliability of the instrument and the audit process exist. Future research should include governmental and commercial OHS program assessments and related environmental management systems and their attendant audit protocols.

  6. Study of turboprop systems reliability and maintenance costs

    NASA Technical Reports Server (NTRS)

    1978-01-01

    The overall reliability and maintenance costs (R&MC's) of past and current turboprop systems were examined. Maintenance cost drivers were found to be scheduled overhaul (40%), lack of modularity particularly in the propeller and reduction gearbox, and lack of inherent durability (reliability) of some parts. Comparisons were made between the 501-D13/54H60 turboprop system and the widely used JT8D turbofan. It was found that the total maintenance cost per flight hour of the turboprop was 75% higher than that of the JT8D turbofan. Part of this difference was due to propeller and gearbox costs being higher than those of the fan and reverser, but most of the difference was in the engine core where the older technology turboprop core maintenance costs were nearly 70 percent higher than for the turbofan. The estimated maintenance cost of both the advanced turboprop and advanced turbofan were less than the JT8D. The conclusion was that an advanced turboprop and an advanced turbofan, using similar cores, will have very competitive maintenance costs per flight hour.

  7. System life and reliability modeling for helicopter transmissions

    NASA Technical Reports Server (NTRS)

    Savage, M.; Brikmanis, C. K.

    1986-01-01

    A computer program which simulates life and reliability of helicopter transmissions is presented. The helicopter transmissions may be composed of spiral bevel gear units and planetary gear units - alone, in series or in parallel. The spiral bevel gear units may have either single or dual input pinions, which are identical. The planetary gear units may be stepped or unstepped and the number of planet gears carried by the planet arm may be varied. The reliability analysis used in the program is based on the Weibull distribution lives of the transmission components. The computer calculates the system lives and dynamic capacities of the transmission components and the transmission. The system life is defined as the life of the component or transmission at an output torque at which the probability of survival is 90 percent. The dynamic capacity of a component or transmission is defined as the output torque which can be applied for one million output shaft cycles for a probability of survival of 90 percent. A complete summary of the life and dynamic capacity results is produced by the program.

  8. Space Shuttle Program Primary Avionics Software System (PASS) Success Legacy - Quality and Reliability Date

    NASA Technical Reports Server (NTRS)

    Orr, James K.; Peltier, Daryl

    2010-01-01

    Thsi slide presentation reviews the avionics software system on board the space shuttle, with particular emphasis on the quality and reliability. The Primary Avionics Software System (PASS) provides automatic and fly-by-wire control of critical shuttle systems which executes in redundant computers. Charts given show the number of space shuttle flights vs time, PASS's development history, and other charts that point to the reliability of the system's development. The reliability of the system is also compared to predicted reliability.

  9. Classical Perturbation Theory for Monte Carlo Studies of System Reliability

    SciTech Connect

    Lewins, Jeffrey D.

    2001-03-15

    A variational principle for a Markov system allows the derivation of perturbation theory for models of system reliability, with prospects of extension to generalized Markov processes of a wide nature. It is envisaged that Monte Carlo or stochastic simulation will supply the trial functions for such a treatment, which obviates the standard difficulties of direct analog Monte Carlo perturbation studies. The development is given in the specific mode for first- and second-order theory, using an example with known analytical solutions. The adjoint equation is identified with the importance function and a discussion given as to how both the forward and backward (adjoint) fields can be obtained from a single Monte Carlo study, with similar interpretations for the additional functions required by second-order theory. Generalized Markov models with age-dependence are identified as coming into the scope of this perturbation theory.

  10. Reliability Considerations of ULP Scaled CMOS in Spacecraft Systems

    NASA Technical Reports Server (NTRS)

    White, Mark; MacNeal, Kristen; Cooper, Mark

    2012-01-01

    NASA, the aerospace community, and other high reliability (hi-rel) users of advanced microelectronic products face many challenges as technology continues to scale into the deep sub-micron region. Decreasing the feature size of CMOS devices not only allows more components to be placed on a single chip, but it increases performance by allowing faster switching (or clock) speeds with reduced power compared to larger scaled devices. Higher performance, and lower operating and stand-by power characteristics of Ultra-Low Power (ULP) microelectronics are not only desirable, but also necessary to meet low power consumption design goals of critical spacecraft systems. The integration of these components in such systems, however, must be balanced with the overall risk tolerance of the project.

  11. A particle swarm model for estimating reliability and scheduling system maintenance

    NASA Astrophysics Data System (ADS)

    Puzis, Rami; Shirtz, Dov; Elovici, Yuval

    2016-05-01

    Modifying data and information system components may introduce new errors and deteriorate the reliability of the system. Reliability can be efficiently regained with reliability centred maintenance, which requires reliability estimation for maintenance scheduling. A variant of the particle swarm model is used to estimate reliability of systems implemented according to the model view controller paradigm. Simulations based on data collected from an online system of a large financial institute are used to compare three component-level maintenance policies. Results show that appropriately scheduled component-level maintenance greatly reduces the cost of upholding an acceptable level of reliability by reducing the need in system-wide maintenance.

  12. Designs and Reliability Evaluations of a Scattered Light Measurement System

    NASA Astrophysics Data System (ADS)

    Lee, Kang-Min

    The purpose of my work was to develop an in-plane stray light measurement system having the advantage of being easily applicable in both motion control and optical configurations. First of all, mechanical designs were conducted based on both 3D modeling and structural analysis through a finite element method (FEM). Optical configurations for both the incident source and the detector were designed to achieve minimum observed source convergence angle of the system. The control panel and micro stepping system were programmed for automated measurement. Finally, the designed system was calibrated and aligned. In order to evaluate the system reliability for scatter measurements from various surface conditions, a total of 9 samples were used. Scattering analysis for bidirectional scatter distribution functions of the samples were conducted: rough surface, smooth surface and small particles. ABg model, Rayleigh-Rice theory and Generalized Harvey-Shack theory were used to verify the scatter measurements. The results indicate that the designed system was appropriately developed for measuring scattering phenomena by rough surface, smooth surface and small particles.

  13. A Reliable Wireless Control System for Tomato Hydroponics

    PubMed Central

    Ibayashi, Hirofumi; Kaneda, Yukimasa; Imahara, Jungo; Oishi, Naoki; Kuroda, Masahiro; Mineno, Hiroshi

    2016-01-01

    Agricultural systems using advanced information and communication (ICT) technology can produce high-quality crops in a stable environment while decreasing the need for manual labor. The system collects a wide variety of environmental data and provides the precise cultivation control needed to produce high value-added crops; however, there are the problems of packet transmission errors in wireless sensor networks or system failure due to having the equipment in a hot and humid environment. In this paper, we propose a reliable wireless control system for hydroponic tomato cultivation using the 400 MHz wireless band and the IEEE 802.15.6 standard. The 400 MHz band, which is lower than the 2.4 GHz band, has good obstacle diffraction, and zero-data-loss communication is realized using the guaranteed time-slot method supported by the IEEE 802.15.6 standard. In addition, this system has fault tolerance and a self-healing function to recover from faults such as packet transmission failures due to deterioration of the wireless communication quality. In our basic experiments, the 400 MHz band wireless communication was not affected by the plants’ growth, and the packet error rate was less than that of the 2.4 GHz band. In summary, we achieved a real-time hydroponic liquid supply control with no data loss by applying a 400 MHz band WSN to hydroponic tomato cultivation. PMID:27164105

  14. A Reliable Wireless Control System for Tomato Hydroponics.

    PubMed

    Ibayashi, Hirofumi; Kaneda, Yukimasa; Imahara, Jungo; Oishi, Naoki; Kuroda, Masahiro; Mineno, Hiroshi

    2016-05-05

    Agricultural systems using advanced information and communication (ICT) technology can produce high-quality crops in a stable environment while decreasing the need for manual labor. The system collects a wide variety of environmental data and provides the precise cultivation control needed to produce high value-added crops; however, there are the problems of packet transmission errors in wireless sensor networks or system failure due to having the equipment in a hot and humid environment. In this paper, we propose a reliable wireless control system for hydroponic tomato cultivation using the 400 MHz wireless band and the IEEE 802.15.6 standard. The 400 MHz band, which is lower than the 2.4 GHz band, has good obstacle diffraction, and zero-data-loss communication is realized using the guaranteed time-slot method supported by the IEEE 802.15.6 standard. In addition, this system has fault tolerance and a self-healing function to recover from faults such as packet transmission failures due to deterioration of the wireless communication quality. In our basic experiments, the 400 MHz band wireless communication was not affected by the plants' growth, and the packet error rate was less than that of the 2.4 GHz band. In summary, we achieved a real-time hydroponic liquid supply control with no data loss by applying a 400 MHz band WSN to hydroponic tomato cultivation.

  15. Analysis of the reliability of submersible centrifugal electric pumping systems

    SciTech Connect

    Shilyaev, V.A.; Solodovnikov, G.G.; Vikhman, R.G.; Koshelev, V.A.; Zhitina, G.S.; Chirkova, N.I.

    1987-01-01

    A modern submersible centrifugal electric pumping system (SCEPS) for oil production consists of a submersible part which includes a centrifugal pump, an electric motor, a hydroprotection arrangement, a cable line, and an aboveground part that includes a control station and a transformer. The author discusses the mean service life of the submersible part of the SCEPS as the most important parameter of reliability of the SCEPS. The effect of the operating factors is assessed by calculating the mean service life of the submersible part of the typical SCEPS, making allowance for failures resulting from all causes. The mean operating time until failure of the submersible part of the new SCEPS due to design and technological error was determined.

  16. FAA center for aviation systems reliability: an overview

    NASA Astrophysics Data System (ADS)

    Brasche, Lisa J. H.

    1996-11-01

    The FAA Center for Aviation Systems Reliability has as its objectives: to develop quantitative nondestructive evaluation (NDE) methods for aircraft structures and materials, including prototype instrumentation, software, techniques and procedures; and to develop and maintain comprehensive education and training programs specific to the inspection of aviation structures. The program, which includes contributions from Iowa State University, Northwestern University, Wayne State University, Tuskegee University, AlliedSignal Propulsion Engines, General Electric Aircraft Engines and Pratt and Whitney, has been in existence since 1990. Efforts under way include: development of inspection for adhesively bonded structures; detection of corrosion; development of advanced NDE concepts that form the basis for an inspection simulator; improvements of titanium inspection as part of the Engine Titanium Consortium; development of education and training program. An overview of the efforts underway will be provided with focus on those technologies closest to technology transfer.

  17. Reliable sources and uncertain decisions in multisensor systems

    NASA Astrophysics Data System (ADS)

    Minor, Christian; Johnson, Kevin

    2015-05-01

    Conflict among information sources is a feature of fused multisource and multisensor systems. Accordingly, the subject of conflict resolution has a long history in the literature of data fusion algorithms such as that of Dempster-Shafer theory (DS). Most conflict resolution strategies focus on distributing the conflict among the elements of the frame of discernment (the set of hypotheses that describe the possible decisions for which evidence is obtained) through rescaling of the evidence. These "closed-world" strategies imply that conflict is due to the uncertainty in evidence sources stemming from their reliability. An alternative approach is the "open-world" hypothesis, which allows for the presence of "unknown" elements not included in the original frame of discernment. Here, conflict must be considered as a result of uncertainty in the frame of the discernment, rather than solely the province of evidence sources. Uncertainty in the operating environment of a fused system is likely to appear as an open-world scenario. Understanding the origin of conflict (source versus frame of discernment uncertainty) is a challenging area for research in fused systems. Determining the ratio of these uncertainties provides useful insights into the operation of fused systems and confidence in their decisions for a variety of operating environments. Results and discussion for the computation of these uncertainties are presented for several combination rules with simulated data sets.

  18. First Stage of a Highly Reliable Reusable Launch System

    NASA Technical Reports Server (NTRS)

    Kloesel, Kurt J.; Pickrel, Jonathan B.; Sayles, Emily L.; Wright, Michael; Marriott, Darin; Holland, Leo; Kuznetsov, Stephen

    2009-01-01

    Electromagnetic launch assist has the potential to provide a highly reliable reusable first stage to a space access system infrastructure at a lower overall cost. This paper explores the benefits of a smaller system that adds the advantages of a high specific impulse air-breathing stage and supersonic launch speeds. The method of virtual specific impulse is introduced as a tool to emphasize the gains afforded by launch assist. Analysis shows launch assist can provide a 278-s virtual specific impulse for a first-stage solid rocket. Additional trajectory analysis demonstrates that a system composed of a launch-assisted first-stage ramjet plus a bipropellant second stage can provide a 48-percent gross lift-off weight reduction versus an all-rocket system. The combination of high-speed linear induction motors and ramjets is identified, as the enabling technologies and benchtop prototypes are investigated. The high-speed response of a standard 60 Hz linear induction motor was tested with a pulse width modulated variable frequency drive to 150 Hz using a 10-lb load, achieving 150 mph. A 300-Hz stator-compensated linear induction motor was constructed and static-tested to 1900 lbf average. A matching ramjet design was developed for use on the 300-Hz linear induction motor.

  19. ICAROUS - Integrated Configurable Algorithms for Reliable Operations Of Unmanned Systems

    NASA Technical Reports Server (NTRS)

    Consiglio, María; Muñoz, César; Hagen, George; Narkawicz, Anthony; Balachandran, Swee

    2016-01-01

    NASA's Unmanned Aerial System (UAS) Traffic Management (UTM) project aims at enabling near-term, safe operations of small UAS vehicles in uncontrolled airspace, i.e., Class G airspace. A far-term goal of UTM research and development is to accommodate the expected rise in small UAS traffic density throughout the National Airspace System (NAS) at low altitudes for beyond visual line-of-sight operations. This paper describes a new capability referred to as ICAROUS (Integrated Configurable Algorithms for Reliable Operations of Unmanned Systems), which is being developed under the UTM project. ICAROUS is a software architecture comprised of highly assured algorithms for building safety-centric, autonomous, unmanned aircraft applications. Central to the development of the ICAROUS algorithms is the use of well-established formal methods to guarantee higher levels of safety assurance by monitoring and bounding the behavior of autonomous systems. The core autonomy-enabling capabilities in ICAROUS include constraint conformance monitoring and contingency control functions. ICAROUS also provides a highly configurable user interface that enables the modular integration of mission-specific software components.

  20. Reliability study of an emerging fire suppression system

    DOE PAGES

    Miller, David A.; Rossati, Lyric M.; Fritz, Nathan K.; ...

    2015-11-01

    Self-contained fire extinguishers are a robust, reliable and minimally invasive means of fire suppression for gloveboxes. Plutonium gloveboxes are known to present harsh environmental conditions for polymer materials, these include radiation damage and chemical exposure, both of which tend to degrade the lifetime of engineered polymer components. The primary component of interest in self-contained fire extinguishers is the nylon 6-6 machined tube that comprises the main body of the system.Thermo-mechanical modeling and characterization of nylon 6-6 for use in plutonium glovebox applications has been carried out. Data has been generated regarding property degradation leading to poor, or reduced, engineering performancemore » of nylon 6-6 components. In this study, nylon 6-6 tensile specimens conforming to the casing of self-contained fire extinguisher systems have been exposed to hydrochloric, nitric, and sulfuric acids. This information was used to predict the performance of a load bearing engineering component comprised of nylon 6-6 and designed to operate in a consistent manner over a specified time period. The study provides a fundamental understanding of the engineering performance of the fire suppression system and the effects of environmental degradation due to acid exposure on engineering performance. Data generated help identify the limitations of self-contained fire extinguishers. No critical areas of concern for plutonium glovebox applications of nylon 6-6 have been identified when considering exposure to mineral acid.« less

  1. Reliability study of an emerging fire suppression system

    SciTech Connect

    Miller, David A.; Rossati, Lyric M.; Fritz, Nathan K.; Cournoyer, Michael E.; Granzow, Howard N.

    2015-11-01

    Self-contained fire extinguishers are a robust, reliable and minimally invasive means of fire suppression for gloveboxes. Plutonium gloveboxes are known to present harsh environmental conditions for polymer materials, these include radiation damage and chemical exposure, both of which tend to degrade the lifetime of engineered polymer components. The primary component of interest in self-contained fire extinguishers is the nylon 6-6 machined tube that comprises the main body of the system.Thermo-mechanical modeling and characterization of nylon 6-6 for use in plutonium glovebox applications has been carried out. Data has been generated regarding property degradation leading to poor, or reduced, engineering performance of nylon 6-6 components. In this study, nylon 6-6 tensile specimens conforming to the casing of self-contained fire extinguisher systems have been exposed to hydrochloric, nitric, and sulfuric acids. This information was used to predict the performance of a load bearing engineering component comprised of nylon 6-6 and designed to operate in a consistent manner over a specified time period. The study provides a fundamental understanding of the engineering performance of the fire suppression system and the effects of environmental degradation due to acid exposure on engineering performance. Data generated help identify the limitations of self-contained fire extinguishers. No critical areas of concern for plutonium glovebox applications of nylon 6-6 have been identified when considering exposure to mineral acid.

  2. Data driven CAN node reliability assessment for manufacturing system

    NASA Astrophysics Data System (ADS)

    Zhang, Leiming; Yuan, Yong; Lei, Yong

    2017-01-01

    The reliability of the Controller Area Network(CAN) is critical to the performance and safety of the system. However, direct bus-off time assessment tools are lacking in practice due to inaccessibility of the node information and the complexity of the node interactions upon errors. In order to measure the mean time to bus-off(MTTB) of all the nodes, a novel data driven node bus-off time assessment method for CAN network is proposed by directly using network error information. First, the corresponding network error event sequence for each node is constructed using multiple-layer network error information. Then, the generalized zero inflated Poisson process(GZIP) model is established for each node based on the error event sequence. Finally, the stochastic model is constructed to predict the MTTB of the node. The accelerated case studies with different error injection rates are conducted on a laboratory network to demonstrate the proposed method, where the network errors are generated by a computer controlled error injection system. Experiment results show that the MTTB of nodes predicted by the proposed method agree well with observations in the case studies. The proposed data driven node time to bus-off assessment method for CAN networks can successfully predict the MTTB of nodes by directly using network error event data.

  3. Significant Inter-Test Reliability across Approximate Number System Assessments

    PubMed Central

    DeWind, Nicholas K.; Brannon, Elizabeth M.

    2016-01-01

    The approximate number system (ANS) is the hypothesized cognitive mechanism that allows adults, infants, and animals to enumerate large sets of items approximately. Researchers usually assess the ANS by having subjects compare two sets and indicate which is larger. Accuracy or Weber fraction is taken as an index of the acuity of the system. However, as Clayton et al. (2015) have highlighted, the stimulus parameters used when assessing the ANS vary widely. In particular, the numerical ratio between the pairs, and the way in which non-numerical features are varied often differ radically between studies. Recently, Clayton et al. (2015) found that accuracy measures derived from two commonly used stimulus sets are not significantly correlated. They argue that a lack of inter-test reliability threatens the validity of the ANS construct. Here we apply a recently developed modeling technique to the same data set. The model, by explicitly accounting for the effect of numerical ratio and non-numerical features, produces dependent measures that are less perturbed by stimulus protocol. Contrary to their conclusion we find a significant correlation in Weber fraction across the two stimulus sets. Nevertheless, in agreement with Clayton et al. (2015) we find that different protocols do indeed induce differences in numerical acuity and the degree of influence of non-numerical stimulus features. These findings highlight the need for a systematic investigation of how protocol idiosyncrasies affect ANS assessments. PMID:27014126

  4. Systems Analysis Programs for Hands-On Integrated Reliability Evaluations.

    SciTech Connect

    2014-08-01

    Version 00 The U.S. Nuclear Regulatory Commission (NRC) has developed a powerful personal computer (PC) software application for performing probabilistic risk assessments (PRAs), called Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Version 8. Using SAPHIRE 8 on a PC, an analyst can perform a PRA for any complex system, facility, or process. Regarding nuclear power plants, SAPHIRE can be used to model a plant's response to initiating events, quantify associated core damage frequencies, and identify important contributors to core damage (Level 1 PRA). It can also be used to evaluate containment failure and release models for severe accident conditions, given that core damage has occurred (Level 2 PRA). It can be used for a PRA assuming that the reactor is at full power, at low power, or at shutdown conditions. Furthermore, it can be used to analyze both internal and external initiating events, and it has special features for transforming models built for internal event analysis to models for external event analysis. It can also be used in a limited manner to quantify risk for release consequences to both the public and the environment (Level 3 PRA). For all of these models, SAPHIRE can evaluate the uncertainty inherent in the probabilistic models. SAPHIRE has evolved with advances in computer technology.

  5. 75 FR 14097 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-24

    ... Reliability Organization Definition of Bulk Electric System March 18, 2010. AGENCY: Federal Energy Regulatory... Electric Reliability Organization (ERO) to revise its definition of the term ``bulk electric system'' to... direct the Electric Reliability Organization (ERO) to revise its definition of the term ``bulk...

  6. Standby cooling system for a fluidized bed boiler

    DOEpatents

    Crispin, Larry G.; Weitzel, Paul S.

    1990-01-01

    A system for protecting components including the heat exchangers of a fluidized bed boiler against thermal mismatch. The system includes an injection tank containing an emergency supply of heated and pressurized feedwater. A heater is associated with the injection tank to maintain the temperature of the feedwater in the tank at or about the same temperature as that of the feedwater in the heat exchangers. A pressurized gas is supplied to the injection tank to cause feedwater to flow from the injection tank to the heat exchangers during thermal mismatch.

  7. A Reliability Test of a Complex System Based on Empirical Likelihood

    PubMed Central

    Zhang, Jun; Hui, Yongchang

    2016-01-01

    To analyze the reliability of a complex system described by minimal paths, an empirical likelihood method is proposed to solve the reliability test problem when the subsystem distributions are unknown. Furthermore, we provide a reliability test statistic of the complex system and extract the limit distribution of the test statistic. Therefore, we can obtain the confidence interval for reliability and make statistical inferences. The simulation studies also demonstrate the theorem results. PMID:27760130

  8. A Model for Predicting Integrated Man-Machine System Reliability: Model Logic and Description

    DTIC Science & Technology

    1974-11-01

    A MODEL FOR PREDICTING INTEGRATED MAN-MACHINE SYSTEMS RELIABILITY prepared for Naval Si nand Deparrmem aw nr. Con :’III’lit UNCLASSIFIED...was substantially modified so as to allow its use for system reliability and system availability predictive purposes. The resultant new model is...from 4 to 20 members was substantially modified so as to allow its use for system reliability and system availability predictive purposes. The

  9. Prevention of corrosion-related failures in condensers and feedwater heaters

    SciTech Connect

    Beavers, J.A.; Agrawal, A.K.; Berry, W.E.

    1982-12-01

    The common alloys used for tubing in power plant feedwater heaters and condensers are identified and the major corrosion problems encountered in these components are described. The frequency of failure and failure modes in both components are shown to be alloy specific. Some corrosion problems are shown to be controllable through minor design modifications in the equipment and others through judicious selection of alloys. In condensers, alloy selection is most effective when based on tube location. In feedwater heaters, strict control of water quality is shown to be necessary with most alloys to minimize corrosion problems. Benefits of some auxiliary techniques for preventing corrosion attack include coating and cathodic protection of the tube sheet and cooling water intake screens.

  10. Systems astrobiology for a reliable biomarker on exo-worlds

    NASA Astrophysics Data System (ADS)

    Chela Flores, Julian

    2013-04-01

    Although astrobiology is a science midway between biology and astrophysics, it has surprisingly remained largely disconnected from recent trends in certain branches of both of these disciplines. Aiming at discovering how systems properties emerge has proved valuable in chemistry and in biology and should also yield insights into astrobiology. This is feasible since new large data banks in the case of astrobiology are of a geophysical/astronomical kind, rather than the also large molecular biology data that are used for questions related firstly, to genetics in a systems context and secondly, to biochemistry. The application of systems biology is illustrated for our own planetary system, where 3 Earth-like planets are within the habitable zone of a G2V star and where the process of photosynthesis has led to a single oxygenic atmosphere that was triggered during the Great Oxidation Event some 2,5 billion years before the present. The significance of the biogenic origin of a considerable fraction of our atmosphere has been discussed earlier (Kiang et al., 2007). Bonding of O2 ensures that it is stable enough to accumulate in a world's atmosphere if triggered by a living process. The reduction of F and Cl deliver energy release per e+-transfer, but unlike O2 the weaker bonding properties inhibit large atmospheric accumulation (Catling et al., 2005). The evolution of O2-producing photosynthesis is very likely on exo-worlds (Wolstencroft and Raven, 2002). With our simplifying assumption of evolutionary convergence, we show how to probe for a reliable biomarker in the exo-atmospheres of planets, or their satellites, orbiting stars of different luminosities and ages (Chela-Flores, 2013). We treat the living process as a system of exo-environments capable of radically modifying their geology and atmospheres, both for exo-planets, and especially for exo-moons, the presence of which can be extracted from the Kepler data (Kipping et al., 2012). What we are learning about the

  11. Renewal of the Control System and Reliable Long Term Operation of the LHD Cryogenic System

    NASA Astrophysics Data System (ADS)

    Mito, T.; Iwamoto, A.; Oba, K.; Takami, S.; Moriuchi, S.; Imagawa, S.; Takahata, K.; Yamada, S.; Yanagi, N.; Hamaguchi, S.; Kishida, F.; Nakashima, T.

    The Large Helical Device (LHD) is a heliotron-type fusion plasma experimental machine which consists of a fully superconducting magnet system cooled by a helium refrigerator having a total equivalent cooling capacity of 9.2 kW@4.4 K. Seventeenplasma experimental campaigns have been performed successfully since1997 with high reliability of 99%. However, sixteen years have passed from the beginning of the system operation. Improvements are being implementedto prevent serious failures and to pursue further reliability.The LHD cryogenic control system was designed and developed as an open system utilizing latest control equipment of VME controllers and UNIX workstations at the construction time. Howeverthe generation change of control equipment has been advanced. Down-sizing of control deviceshas beenplanned from VME controllers to compact PCI controllers in order to simplify the system configuration and to improve the system reliability. The new system is composed of compact PCI controller and remote I/O connected with EtherNet/IP. Making the system redundant becomes possible by doubling CPU, LAN, and remote I/O respectively. The smooth renewal of the LHD cryogenic controlsystem and the further improvement of the cryogenic system reliability are reported.

  12. Differential Evolution Based Intelligent System State Search Method for Composite Power System Reliability Evaluation

    NASA Astrophysics Data System (ADS)

    Bakkiyaraj, Ashok; Kumarappan, N.

    2015-09-01

    This paper presents a new approach for evaluating the reliability indices of a composite power system that adopts binary differential evolution (BDE) algorithm in the search mechanism to select the system states. These states also called dominant states, have large state probability and higher loss of load curtailment necessary to maintain real power balance. A chromosome of a BDE algorithm represents the system state. BDE is not applied for its traditional application of optimizing a non-linear objective function, but used as tool for exploring more number of dominant states by producing new chromosomes, mutant vectors and trail vectors based on the fitness function. The searched system states are used to evaluate annualized system and load point reliability indices. The proposed search methodology is applied to RBTS and IEEE-RTS test systems and results are compared with other approaches. This approach evaluates the indices similar to existing methods while analyzing less number of system states.

  13. Conceptual Software Reliability Prediction Models for Nuclear Power Plant Safety Systems

    SciTech Connect

    Johnson, G.; Lawrence, D.; Yu, H.

    2000-04-03

    The objective of this project is to develop a method to predict the potential reliability of software to be used in a digital system instrumentation and control system. The reliability prediction is to make use of existing measures of software reliability such as those described in IEEE Std 982 and 982.2. This prediction must be of sufficient accuracy to provide a value for uncertainty that could be used in a nuclear power plant probabilistic risk assessment (PRA). For the purposes of the project, reliability was defined to be the probability that the digital system will successfully perform its intended safety function (for the distribution of conditions under which it is expected to respond) upon demand with no unintended functions that might affect system safety. The ultimate objective is to use the identified measures to develop a method for predicting the potential quantitative reliability of a digital system. The reliability prediction models proposed in this report are conceptual in nature. That is, possible prediction techniques are proposed and trial models are built, but in order to become a useful tool for predicting reliability, the models must be tested, modified according to the results, and validated. Using methods outlined by this project, models could be constructed to develop reliability estimates for elements of software systems. This would require careful review and refinement of the models, development of model parameters from actual experience data or expert elicitation, and careful validation. By combining these reliability estimates (generated from the validated models for the constituent parts) in structural software models, the reliability of the software system could then be predicted. Modeling digital system reliability will also require that methods be developed for combining reliability estimates for hardware and software. System structural models must also be developed in order to predict system reliability based upon the reliability

  14. Reliability and performance evaluation of systems containing embedded rule-based expert systems

    NASA Technical Reports Server (NTRS)

    Beaton, Robert M.; Adams, Milton B.; Harrison, James V. A.

    1989-01-01

    A method for evaluating the reliability of real-time systems containing embedded rule-based expert systems is proposed and investigated. It is a three stage technique that addresses the impact of knowledge-base uncertainties on the performance of expert systems. In the first stage, a Markov reliability model of the system is developed which identifies the key performance parameters of the expert system. In the second stage, the evaluation method is used to determine the values of the expert system's key performance parameters. The performance parameters can be evaluated directly by using a probabilistic model of uncertainties in the knowledge-base or by using sensitivity analyses. In the third and final state, the performance parameters of the expert system are combined with performance parameters for other system components and subsystems to evaluate the reliability and performance of the complete system. The evaluation method is demonstrated in the context of a simple expert system used to supervise the performances of an FDI algorithm associated with an aircraft longitudinal flight-control system.

  15. Reliability Considerations in 3D Stacked Strata Systems

    NASA Astrophysics Data System (ADS)

    Pozder, Scott; Jain, Ankur; Jones, Robert; Huang, Zhihong; Justison, Patrick; Chatterjee, Ritwik

    2009-06-01

    The bonding of multiple silicon strata to form stacked circuits with high bandwidth connections, increased circuit densities, decreased latency and the capability to stack disparate technologies is increasingly gaining interest in the microelectronics industry. Stacking has been demonstrated using bom dielectric-to-dielectric and metal-to-metal bonds for die and wafer stratum bonding. The considerable thermal, mechanical and electromigration reliability challenges resulting from such bonding has been the focus of some recently reported work. In mis paper, the bond reliability of various bonding types, including wafer-to-wafer dielectric bond, die-to-wafer Cu/Sn-to-Cu bond and a simultaneous organic adhesive with Cu/Sn-to-Cu bond is discussed. Thermomechanical and electromigration characterization of the die-to-wafer 3D structures is also discussed. Results indicate that the intrinsic reliability of these structures can be as robust as current 2D technologies.

  16. Reliability of the Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt.

    PubMed

    Aucone, E J; Raphael, A J; Golden, C J; Espe-Pfeifer, P; Seldon, J; Pospisil, T; Dornheim, L; Proctor-Weber, Z; Calabria, M

    1999-09-01

    This study assesses the interrater reliability of the revised Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt Test (BGT). The API scoring system identifies 207 possible distortions in a BGT protocol. Agreement across nine raters exceeded 90% for each of three clinical protocols. Kappa statistics indicated that the API system exhibited good interrater reliability. Further research is necessary in such areas as test-retest reliability and validity to further demonstrate the effectiveness of the procedure.

  17. Verification of Triple Modular Redundancy Insertion for Reliable and Trusted Systems

    NASA Technical Reports Server (NTRS)

    Berg, Melanie; LaBel, Kenneth

    2016-01-01

    If a system is required to be protected using triple modular redundancy (TMR), improper insertion can jeopardize the reliability and security of the system. Due to the complexity of the verification process and the complexity of digital designs, there are currently no available techniques that can provide complete and reliable confirmation of TMR insertion. We propose a method for TMR insertion verification that satisfies the process for reliable and trusted systems.

  18. Reliability evaluation of distribution systems containing renewable distributed generations

    NASA Astrophysics Data System (ADS)

    Alkuhayli, Abdulaziz Abddullah

    Reliability evaluation of distribution networks, including islanded microgrid cases, is presented. The Monte Carlo simulation algorithm is applied to a test network. The network includes three types of distributed energy resources solar photovoltaic (PV), wind turbine (WT) and gas turbine (GT). These distributed generators contribute to supply part of the load during grid-connected mode, but supply the entire load during islanded microgrid operation. PV and WT stochastic models have been used to simulate the randomness of these resources. This study shows that the implementation of distributed generations can improve the reliability of the distribution networks.

  19. Reliability and quality assurance on the MOD 2 wind system

    NASA Technical Reports Server (NTRS)

    Mason, W. E. B.; Jones, B. G.

    1981-01-01

    The Safety, Reliability, and Quality Assurance (R&QA) approach developed for the largest wind turbine generator, the Mod 2, is described. The R&QA approach assures that the machine is not hazardous to the public or to the operating personnel, is operated unattended on a utility grid, demonstrates reliable operation, and helps establish the quality assurance and maintainability requirements for future wind turbine projects. The significant guideline consisted of a failure modes and effects analysis (FMEA) during the design phase, hardware inspections during parts fabrication, and three simple documents to control activities during machine construction and operation.

  20. Approximate Interval Estimation Methods for the Reliability of Systems Using Discrete Component Data

    DTIC Science & Technology

    1990-09-01

    Three lower confidence interval estimation procedures for system reliability of coherent systems with cyclic components are developed and their...components. The combined procedure may yield a reasonably accurate lower confidence interval procedure for the reliability of coherent systems with mixtures of continuous and cyclic components.

  1. ANALYSIS OF SEQUENTIAL FAILURES FOR ASSESSMENT OF RELIABILITY AND SAFETY OF MANUFACTURING SYSTEMS. (R828541)

    EPA Science Inventory

    Assessment of reliability and safety of a manufacturing system with sequential failures is an important issue in industry, since the reliability and safety of the system depend not only on all failed states of system components, but also on the sequence of occurrences of those...

  2. Impact of Fiber Optics on System Reliability and Maintainability

    DTIC Science & Technology

    1988-06-01

    data was obtained through numerous phone contacts, survey respondees and through previously published technical papers. Acknowledgement is also in...5 SECTION II - NUMERICAL RELIABILITY SUMMARY ........... 4 SECTION III - COMPONENTS .. ...................... 61 1. FIBER AND CABLE...429 12-3 Typical OTDR trace ................... 433 12-4 Differing backscatter coefficient trace. ......... .. 435 12-5 Numerical aperture

  3. 78 FR 44475 - Protection System Maintenance Reliability Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-07-24

    ... believes that vendor-issued firmware upgrades for microprocessor relays are common, and verification of... for component types known to have higher levels of reliability (particularly microprocessor-based relays, trip coils, and lockout devices). Microprocessor-based relays, for example, rarely go...

  4. A discussion of system reliability and the relative importance of pumps and valves to overall system availability

    SciTech Connect

    Poole, A.B.

    1996-12-01

    An analysis was undertaken to establish preliminary trends for how component aging can effect failure rates for swing check valves, centrifugal pumps and motor operated valves. These failure rate trends were evaluated over time and linear aging rate models established. The failure rate models were then used with classic reliability theories to estimate reliability as a function of operating time. Reliability theory was also used to establish a simple system reliability model. Using the system model, the relative importance of pumps and valves to the overall system reliability were studied. Conclusions were established relative to overall system availability over time and the relative unavailabilities of the various components studied.

  5. Comparison of reliability performance of group connected and conventional HVDC transmission systems

    SciTech Connect

    Kuruganty, S.

    1995-10-01

    A group connected HVDC transmission scheme is a variant of the unit connection where instead of a single generator, a group of generators are directly connected to the converter. Studies conducted in the past indicated that significant cost reduction can be achieved using this scheme. This is mainly due to the elimination of many components which results in considerable capital and operating cost savings to the utility. Concerns regarding the reliability performance of unit connected schemes were raised, however, there has not been a detailed reliability study conducted. This paper addresses the reliability evaluation aspect of a group connected scheme and compares the reliability performance of the group connected scheme with that of the conventional common collector system. Reliability models for both schemes were developed using a hypothetical system model based on the Nelson River system. Practical system component outage data was used to examine the reliability performance of both schemes.

  6. Rocket engine system reliability analyses using probabilistic and fuzzy logic techniques

    NASA Technical Reports Server (NTRS)

    Hardy, Terry L.; Rapp, Douglas C.

    1994-01-01

    The reliability of rocket engine systems was analyzed by using probabilistic and fuzzy logic techniques. Fault trees were developed for integrated modular engine (IME) and discrete engine systems, and then were used with the two techniques to quantify reliability. The IRRAS (Integrated Reliability and Risk Analysis System) computer code, developed for the U.S. Nuclear Regulatory Commission, was used for the probabilistic analyses, and FUZZYFTA (Fuzzy Fault Tree Analysis), a code developed at NASA Lewis Research Center, was used for the fuzzy logic analyses. Although both techniques provided estimates of the reliability of the IME and discrete systems, probabilistic techniques emphasized uncertainty resulting from randomness in the system whereas fuzzy logic techniques emphasized uncertainty resulting from vagueness in the system. Because uncertainty can have both random and vague components, both techniques were found to be useful tools in the analysis of rocket engine system reliability.

  7. Nuclear electric propulsion operational reliability and crew safety study: NEP systems/modeling report

    NASA Technical Reports Server (NTRS)

    Karns, James

    1993-01-01

    The objective of this study was to establish the initial quantitative reliability bounds for nuclear electric propulsion systems in a manned Mars mission required to ensure crew safety and mission success. Finding the reliability bounds involves balancing top-down (mission driven) requirements and bottom-up (technology driven) capabilities. In seeking this balance we hope to accomplish the following: (1) provide design insights into the achievability of the baseline design in terms of reliability requirements, given the existing technology base; (2) suggest alternative design approaches which might enhance reliability and crew safety; and (3) indicate what technology areas require significant research and development to achieve the reliability objectives.

  8. MONITORING OF LARGE INSTABLE AREAS: system reliability and new tools.

    NASA Astrophysics Data System (ADS)

    Leandro, G.; Mucciarelli, M.; Pellicani, R.; Spilotro, G.

    2009-04-01

    The monitoring of unstable or potentially unstable areas is a necessary operation every time you can not remove the conditions of risk and apply to mitigation measures. In Italian Apennine regions there are many urban or extra-urban areas affected by instability, for which it is impracticable to remove hazard conditions, because of size and cost problems. The technological evolution exportable to the field of land instability monitoring is particularly lively and allows the use of warning systems unthinkable just few years ago. However, the monitoring of unstable or potentially unstable areas requires a very great knowledge of the specific problems, without which the reliability of the system may be dangerously overestimated. The movement may arise, indeed, in areas not covered by instrumentation, or covered with vegetation that prevents the acquisition of both reflected signals in the multi-beam laser techniques and radar signals. Environmental conditions (wind, concentrated sources of light, temperature changes, presence of animals) may also invalidate the accuracy of the measures, by introducing modulations or disturbance at a level well above the threshold of alarm signal, leading consequently to raise the values of the warning threshold. The Authors have gained long experience with the observation and monitoring of some large landslides in the Southern Apennine (Aliano, Buoninventre, Calciano, Carlantino, etc.) and unstable areas also at regional scale. One of the most important experiences is about the case of landslides of extensive areas, where unstable and stables zones coexist along transverse and longitudinal axis. In many of these cases you need the accurate control of the movement at selected points to evaluate the trend of displacement velocity, which can be achieved by means of a single-beam laser. The control of these movements, however, does not provide information on stress pattern into the stable areas. Among the sensitive precursors, acoustic

  9. Reliability and Maintainability Analysis of Fluidic Back-Up Flight Control System and Components.

    DTIC Science & Technology

    1981-09-01

    being used in various aircraft applications are demonstrating extremely high reliability. However, the unique design of new fluidic compo- nents results...in a very limited failure rate data base and prevents the determination of numerical values of fluidic system reliability at a sufficient confidence...Did. 6601 WWINlTTi’ G.ASUFIOATION OF TH PAGE (116 flm e UAK 80227-60 EXECUTIVE SUMMARY BACKGROUND High reliability in flight control systems is achieved

  10. Hydrothermal carbonization (HTC) of wheat straw: influence of feedwater pH prepared by acetic acid and potassium hydroxide.

    PubMed

    Reza, M Toufiq; Rottler, Erwin; Herklotz, Laureen; Wirth, Benjamin

    2015-04-01

    In this study, influence of feedwater pH (2-12) was studied for hydrothermal carbonization (HTC) of wheat straw at 200 and 260°C. Acetic acid and KOH were used as acidic and basic medium, respectively. Hydrochars were characterized by elemental and fiber analyses, SEM, surface area, pore volume and size, and ATR-FTIR, while HTC process liquids were analyzed by HPLC and GC. Both hydrochar and HTC process liquid qualities vary with feedwater pH. At acidic pH, cellulose and elemental carbon increase in hydrochar, while hemicellulose and pseudo-lignin decrease. Hydrochars produced at pH 2 feedwater has 2.7 times larger surface area than that produced at pH 12. It also has the largest pore volume (1.1 × 10(-1) ml g(-1)) and pore size (20.2 nm). Organic acids were increasing, while sugars were decreasing in case of basic feedwater, however, phenolic compounds were present only at 260°C and their concentrations were increasing in basic feedwater.

  11. Fault Tolerance, Reliability and Testability for Distributed Systems.

    DTIC Science & Technology

    1983-02-01

    applications and by the Increasing utilization of distributed computing In this field. The study Is Intended to provide a framework for the... distributed computing with particular emphasis on reports generated by DoD agencies related to C31 activities; on-site reviews of the reliability experience of... distributed computing . This report is intended to provide a foundation for the development of measures and guidelines for the design and evaluation of

  12. Reliability Design to Circuit System in Hard Target Smart Fuze

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhang, Ya

    Hard target smart fuze can adaptively control the the burst point of penetrating projectile. How to improve its circuit working reliability to fit the fuze harsh high-g working environment is studied in this paper. A series of practical measures are taken, such as, propose buffer to fuze circuits; use high quality electronic components; and take circuit redundancy technique. Then the conclusions will provide valuable reference for engineering applications of hard target smart fuze.

  13. Workload, Performance, and Reliability of Digital Computing Systems.

    DTIC Science & Technology

    1980-12-01

    Barlow and F. Proschan. Mathematical Theory of Reliability. John Wiley & Sons, 1965. [ Bazaraa 79] M.S. Bazaraa and C.M. Shetty. Nonlinear Programming...software failures are due to: a) the (static) input data to a progam module presents some peculiarities that the program is not able of handling or, b...at the minimum are not generaly available, this is a typical nonlinear programming problem, subject to nonlinear inequality constraints. Since this

  14. Environmental Control and Life Support System Reliability for Long-Duration Missions Beyond Lower Earth Orbit

    NASA Technical Reports Server (NTRS)

    Sargusingh, Miriam J.; Nelson, Jason R.

    2014-01-01

    NASA has highlighted reliability as critical to future human space exploration, particularly in the area of environmental controls and life support systems. The Advanced Exploration Systems (AES) projects have been encouraged to pursue higher reliability components and systems as part of technology development plans. However, no consensus has been reached on what is meant by improving on reliability, or on how to assess reliability within the AES projects. This became apparent when trying to assess reliability as one of several figures of merit for a regenerable water architecture trade study. In the spring of 2013, the AES Water Recovery Project hosted a series of events at Johnson Space Center with the intended goal of establishing a common language and understanding of NASA's reliability goals, and equipping the projects with acceptable means of assessing the respective systems. This campaign included an educational series in which experts from across the agency and academia provided information on terminology, tools, and techniques associated with evaluating and designing for system reliability. The campaign culminated in a workshop that included members of the Environmental Control and Life Support System and AES communities. The goal of this workshop was to develop a consensus on what reliability means to AES and identify methods for assessing low- to mid-technology readiness level technologies for reliability. This paper details the results of that workshop.

  15. A new method for computing the reliability of consecutive k-out-of-n:F systems

    NASA Astrophysics Data System (ADS)

    Gökdere, Gökhan; Gürcan, Mehmet; Kılıç, Muhammet Burak

    2016-01-01

    In many physical systems, reliability evaluation, such as ones encountered in telecommunications, the design of integrated circuits, microwave relay stations, oil pipeline systems, vacuum systems in accelerators, computer ring networks, and spacecraft relay stations, have had applied consecutive k-out-of-n system models. These systems are characterized as logical connections among the components of the systems placed in lines or circles. In literature, a great deal of attention has been paid to the study of the reliability evaluation of consecutive k-out-of-n systems. In this paper, we propose a new method to compute the reliability of consecutive k-out-of-n:F systems, with n linearly and circularly arranged components. The proposed method provides a simple way for determining the system failure probability. Also, we write R-Project codes based on our proposed method to compute the reliability of the linear and circular systems which have a great number of components.

  16. Wind energy Computerized Maintenance Management System (CMMS) : data collection recommendations for reliability analysis.

    SciTech Connect

    Peters, Valerie A.; Ogilvie, Alistair; Veers, Paul S.

    2009-09-01

    This report addresses the general data requirements for reliability analysis of fielded wind turbines and other wind plant equipment. The report provides a list of the data needed to support reliability and availability analysis, and gives specific recommendations for a Computerized Maintenance Management System (CMMS) to support automated analysis. This data collection recommendations report was written by Sandia National Laboratories to address the general data requirements for reliability analysis of fielded wind turbines. This report is intended to help the reader develop a basic understanding of what data are needed from a Computerized Maintenance Management System (CMMS) and other data systems, for reliability analysis. The report provides: (1) a list of the data needed to support reliability and availability analysis; and (2) specific recommendations for a CMMS to support automated analysis. Though written for reliability analysis of wind turbines, much of the information is applicable to a wider variety of equipment and a wider variety of analysis and reporting needs.

  17. HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 1: HARP introduction and user's guide

    NASA Technical Reports Server (NTRS)

    Bavuso, Salvatore J.; Rothmann, Elizabeth; Dugan, Joanne Bechta; Trivedi, Kishor S.; Mittal, Nitin; Boyd, Mark A.; Geist, Robert M.; Smotherman, Mark D.

    1994-01-01

    The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed to be compatible with most computing platforms and operating systems, and some programs have been beta tested, within the aerospace community for over 8 years. Volume 1 provides an introduction to the HARP program. Comprehensive information on HARP mathematical models can be found in the references.

  18. How reliable are clinical systems in the UK NHS? A study of seven NHS organisations

    PubMed Central

    Franklin, Bryony Dean; Moorthy, Krishna; Cooke, Matthew W; Vincent, Charles

    2012-01-01

    Background It is well known that many healthcare systems have poor reliability; however, the size and pervasiveness of this problem and its impact has not been systematically established in the UK. The authors studied four clinical systems: clinical information in surgical outpatient clinics, prescribing for hospital inpatients, equipment in theatres, and insertion of peripheral intravenous lines. The aim was to describe the nature, extent and variation in reliability of these four systems in a sample of UK hospitals, and to explore the reasons for poor reliability. Methods Seven UK hospital organisations were involved; each system was studied in three of these. The authors took delivery of the systems' intended outputs to be a proxy for the reliability of the system as a whole. For example, for clinical information, 100% reliability was defined as all patients having an agreed list of clinical information available when needed during their appointment. Systems factors were explored using semi-structured interviews with key informants. Common themes across the systems were identified. Results Overall reliability was found to be between 81% and 87% for the systems studied, with significant variation between organisations for some systems: clinical information in outpatient clinics ranged from 73% to 96%; prescribing for hospital inpatients 82–88%; equipment availability in theatres 63–88%; and availability of equipment for insertion of peripheral intravenous lines 80–88%. One in five reliability failures were associated with perceived threats to patient safety. Common factors causing poor reliability included lack of feedback, lack of standardisation, and issues such as access to information out of working hours. Conclusions Reported reliability was low for the four systems studied, with some common factors behind each. However, this hides significant variation between organisations for some processes, suggesting that some organisations have managed to create

  19. A simulation model for reliability evaluation of space station power systems

    SciTech Connect

    Singh, C.; Patton, A.D.; Kumar, M. ); Wagner, H. )

    1991-03-01

    This paper presents a detailed simulation model for reliability evaluation of space station electrical power systems. Dependence of reliability and storage characteristics during the sun and eclipse periods is considered. The charging and discharging of energy storage modules is included on a continuous basis. Sample system studies are also presented.

  20. 75 FR 72909 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-11-26

    ... Definition of Bulk Electric System; Final Rule #0;#0;Federal Register / Vol. 75 , No. 227 / Friday, November... CFR Part 40 Revision to Electric Reliability Organization Definition of Bulk Electric System Issued... Proposed Rulemaking to require the Electric Reliability Organization (ERO) to revise its definition of...

  1. A reliable in vitro fruiting system for armillaria mellea for evaluation of agrobacterium tumefaciens transformation vectors

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Armillaria mellea is a serious pathogen of horticultural and agricultural systems in Europe and North America. The lack of a reliable in vitro fruiting system has hindered research, and necessitated dependence on intermittently available wild-collected basidiospores. Here we describe a reliable, rep...

  2. Mechanical System Reliability and Cost Integration Using a Sequential Linear Approximation Method

    NASA Technical Reports Server (NTRS)

    Kowal, Michael T.

    1997-01-01

    The development of new products is dependent on product designs that incorporate high levels of reliability along with a design that meets predetermined levels of system cost. Additional constraints on the product include explicit and implicit performance requirements. Existing reliability and cost prediction methods result in no direct linkage between variables affecting these two dominant product attributes. A methodology to integrate reliability and cost estimates using a sequential linear approximation method is proposed. The sequential linear approximation method utilizes probability of failure sensitivities determined from probabilistic reliability methods as well a manufacturing cost sensitivities. The application of the sequential linear approximation method to a mechanical system is demonstrated.

  3. A support architecture for reliable distributed computing systems

    NASA Technical Reports Server (NTRS)

    Dasgupta, Partha; Leblanc, Richard J., Jr.

    1988-01-01

    The Clouds project is well underway to its goal of building a unified distributed operating system supporting the object model. The operating system design uses the object concept of structuring software at all levels of the system. The basic operating system was developed and work is under progress to build a usable system.

  4. The dynamics of a turbine-driven reactor feedwater pump and identification of related parameters in the Kuosheng power station

    SciTech Connect

    Shihjen Wang; Chunsheng Chien ); Suhchyn Jeng )

    1993-09-01

    In the Kuosheng nuclear power station, a turbine-driven reactor feedwater pump (TDRFP) is used to drive feedwater to the reactor pressure vessel (RPV). The performance of the TDRFP plays an important role in the safe operation of the nuclear power station as it governs the water inventory in the RPV. The dynamics of the TDRFP in the Kuosheng nuclear power station are simulated, and related parameters are identified by the simplex search method. A reactor feedwater pump (RFP) trip test was performed during the startup test of the Kuosheng nuclear power station. This RFP trip transient was selected for this study because it simplifies the identification process. The ratio of rated torque to moments of inertia, parameters related to the characteristic H-Q curve, and parameters related to the characteristic T-Q curve are verified.

  5. Applying reliability analysis to design electric power systems for More-electric aircraft

    NASA Astrophysics Data System (ADS)

    Zhang, Baozhu

    The More-Electric Aircraft (MEA) is a type of aircraft that replaces conventional hydraulic and pneumatic systems with electrically powered components. These changes have significantly challenged the aircraft electric power system design. This thesis investigates how reliability analysis can be applied to automatically generate system topologies for the MEA electric power system. We first use a traditional method of reliability block diagrams to analyze the reliability level on different system topologies. We next propose a new methodology in which system topologies, constrained by a set reliability level, are automatically generated. The path-set method is used for analysis. Finally, we interface these sets of system topologies with control synthesis tools to automatically create correct-by-construction control logic for the electric power system.

  6. Risk Based Reliability Centered Maintenance of DOD Fire Protection Systems

    DTIC Science & Technology

    1999-01-01

    Interface Location In Fire water supply Dry pipe system control valve In Air supply system Air supply system compressor In Priming water Priming, water...outlet Table 2.18 Deluge, Water Spray, and Pre-action System Boundaries Interface Type Bounding System/Component Interface Location In Fire water supply... Fire water supply Foam/foam-water system control valve In Foam concentrate pump Pump motor starter In Foam concentrate pump Start signal to the pump

  7. Acquisition of reliable vacuum hardware for large accelerator systems

    SciTech Connect

    Welch, K.M.

    1995-09-06

    Credible and effective communications prove to be the major challenge in the acquisition of reliable vacuum hardware. Technical competence is necessary but not sufficient. The authors must effectively communicate with management, sponsoring agencies, project organizations, service groups, staff and with vendors. Most of Deming`s 14 quality assurance tenants relate to creating an enlightened environment of good communications. All projects progress along six distinct, closely coupled, dynamic phases. All six phases are in a state of perpetual change. These phases and their elements are discussed, with emphasis given to the acquisition phase and its related vocabulary. Large projects require great clarity and rigor as poor communications can be costly. For rigor to be cost effective, it can`t be pedantic. Clarity thrives best in a low-risk, team environment.

  8. Uncertainty quantification: Making predictions of complex reaction systems reliable

    NASA Astrophysics Data System (ADS)

    Russi, Trent; Packard, Andy; Frenklach, Michael

    2010-10-01

    There is increasing need to make chemical reaction models and modeling more predictive. We examine the modeling methodology from the perspective of propagation of uncertainties, those in assumed model parameters along with those in experimental observations. Accepting the length of the uncertainty interval in the predicted property as a measure of model predictiveness, we examine methodological factors affecting it. Employing the recently introduced technique of Data Collaboration, we show that even 'harmless' assumptions, invoked explicitly or implicitly to alleviate a burden of numerical procedures, could lead to substantial differences in model predictiveness. We also demonstrate that the direct, one-step methodology, such as Data Collaboration, necessarily makes modeling more predictive and thus more reliable than a two-step approach typical of most current methods.

  9. A Study of DSN Traveling Wave Maser System Reliability

    NASA Technical Reports Server (NTRS)

    Stevens, R.; Wiggins, C. P.

    1984-01-01

    Reliability and availability characteristics of the DSN traveling wave maser (TWM) Assemblies are reported for the years 1981 through 1983, the charcteristics determined are: mean time between failures (MTBF) - 1200 hours; mean time to restore service (MTTRS) - 2.5 hours; and availability - 99.83%. The TWM MTBF is very good as compared to other DSN subsystems and assemblies. The TWM MTTRS is currently about three times as long as the average of other DSN subsystems. The dominant cause of TWM failures is contamination of the helium gas in the closed cycle refrigerators. Station configurations that do not provide TWM redundancy are subject to reception outages for long periods of time. Recommendations are made to improve the TWM Assembly availability characteristics for future mission support operations.

  10. Scaled CMOS Reliability and Considerations for Spacecraft Systems: Bottom-Up and Top-Down Perspective

    NASA Technical Reports Server (NTRS)

    White, Mark

    2012-01-01

    New space missions will increasingly rely on more advanced technologies because of system requirements for higher performance, particularly in instruments and high-speed processing. Component-level reliability challenges with scaled CMOS in spacecraft systems from a bottom-up perspective have been presented. Fundamental Front-end and Back-end processing reliability issues with more aggressively scaled parts have been discussed. Effective thermal management from system-level to the componentlevel (top-down) is a key element in overall design of reliable systems. Thermal management in space systems must consider a wide range of issues, including thermal loading of many different components, and frequent temperature cycling of some systems. Both perspectives (top-down and bottom-up) play a large role in robust, reliable spacecraft system design.

  11. Confidence interval procedures for system reliability and applications to competing risks models.

    PubMed

    Hong, Yili; Meeker, William Q

    2014-04-01

    System reliability depends on the reliability of the system's components and the structure of the system. For example, in a competing risks model, the system fails when the weakest component fails. The reliability function and the quantile function of a complicated system are two important metrics for characterizing the system's reliability. When there are data available at the component level, the system reliability can be estimated by using the component level information. Confidence intervals (CIs) are needed to quantify the statistical uncertainty in the estimation. Obtaining system reliability CI procedures with good properties is not straightforward, especially when the system structure is complicated. In this paper, we develop a general procedure for constructing a CI for the system failure-time quantile function by using the implicit delta method. We also develop general procedures for constructing a CI for the cumulative distribution function (cdf) of the system. We show that the recommended procedures are asymptotically valid and have good statistical properties. We conduct simulations to study the finite-sample coverage properties of the proposed procedures and compare them with existing procedures. We apply the proposed procedures to three applications; two applications in competing risks models and an application with a k-out-of-s system. The paper concludes with some discussion and an outline of areas for future research.

  12. Advanced reliability modeling of fault-tolerant computer-based systems

    NASA Technical Reports Server (NTRS)

    Bavuso, S. J.

    1982-01-01

    Two methodologies for the reliability assessment of fault tolerant digital computer based systems are discussed. The computer-aided reliability estimation 3 (CARE 3) and gate logic software simulation (GLOSS) are assessment technologies that were developed to mitigate a serious weakness in the design and evaluation process of ultrareliable digital systems. The weak link is based on the unavailability of a sufficiently powerful modeling technique for comparing the stochastic attributes of one system against others. Some of the more interesting attributes are reliability, system survival, safety, and mission success.

  13. PV system reliability: lessons learned from a fleet of 333 systems

    NASA Astrophysics Data System (ADS)

    Kaushik, A.; Golnas, A.

    2011-09-01

    The levelized cost of energy (LCOE) from PV systems can be reduced by maximizing the energy production of existing/future PV plants through increased availability. This can be achieved by detailed study of root cause and failure analysis of component failures leading to a systematic progress towards improving the reliability of various sub-systems. SunEdison owns/operates ~500 sites across the world and systematically collects field failure data in addition to power output and weather data. Analysis of this information allows following-up on corrective actions to eliminate/minimize the re-occurrence of failures and leads to continuous improvements. This paper will analyze some of the key findings from the system failures as follows: - Inverter failures not only cause most of the system outages, but also result in substantial energy losses. Component failures in PCBs and inverter software/firmware bugs are the most common root cause of system outages - From a systemic root cause perspective, lack of robust quality systems at multiple levels of the supply chain is quite evident, which points toward the need for collectively inculcating the quality culture at every stage of the supply chain - This paper will try to establish the need for "Continuous Improvement Process" (CIP) where systemic issues are confronted and solutions are internalized in the operating procedures as the only path to improving component reliability - For a given level of reliability, cost associated with servicing the plant becomes critical. This paper highlights the importance of using "cost of ownership" metrics for making procurement decisions

  14. Constellation Ground Systems Launch Availability Analysis: Enhancing Highly Reliable Launch Systems Design

    NASA Technical Reports Server (NTRS)

    Gernand, Jeffrey L.; Gillespie, Amanda M.; Monaghan, Mark W.; Cummings, Nicholas H.

    2010-01-01

    Success of the Constellation Program's lunar architecture requires successfully launching two vehicles, Ares I/Orion and Ares V/Altair, in a very limited time period. The reliability and maintainability of flight vehicles and ground systems must deliver a high probability of successfully launching the second vehicle in order to avoid wasting the on-orbit asset launched by the first vehicle. The Ground Operations Project determined which ground subsystems had the potential to affect the probability of the second launch and allocated quantitative availability requirements to these subsystems. The Ground Operations Project also developed a methodology to estimate subsystem reliability, availability and maintainability to ensure that ground subsystems complied with allocated launch availability and maintainability requirements. The verification analysis developed quantitative estimates of subsystem availability based on design documentation; testing results, and other information. Where appropriate, actual performance history was used for legacy subsystems or comparative components that will support Constellation. The results of the verification analysis will be used to verify compliance with requirements and to highlight design or performance shortcomings for further decision-making. This case study will discuss the subsystem requirements allocation process, describe the ground systems methodology for completing quantitative reliability, availability and maintainability analysis, and present findings and observation based on analysis leading to the Ground Systems Preliminary Design Review milestone.

  15. Quality management systems: a reliable proof of conformity.

    PubMed

    Suppo, M

    1997-01-01

    Doubts have been raised about whether proof of conformity via a certified full quality management system is appropriate for in vitro diagnostic products used for screening blood donations, for example, tests for HIV and hepatitis B and C. This article reviews all the arguments and finds in favour of the proposed system because it involves requirements that extend beyond the normal quality system standard.

  16. Software metrics: Software quality metrics for distributed systems. [reliability engineering

    NASA Technical Reports Server (NTRS)

    Post, J. V.

    1981-01-01

    Software quality metrics was extended to cover distributed computer systems. Emphasis is placed on studying embedded computer systems and on viewing them within a system life cycle. The hierarchy of quality factors, criteria, and metrics was maintained. New software quality factors were added, including survivability, expandability, and evolvability.

  17. Switchover software reliability estimate for Paducah Freezer/Sublimer computer systems

    SciTech Connect

    Flanagan, D.M.; Davis, J.N.

    1993-04-01

    K-25 Engineering Division purchased a series of redundant computer systems and developed software for the purpose of providing continuous process monitoring and control for the Freezer/Sublimer equipment in the gaseous diffusion process at the Paducah Gaseous Diffusion Plant. The application software is loaded on two central processing units (CPU) so that in the event of a failure of the primary unit, the processing can switch to the backup unit and continue processing without error. It is the purpose of this document to demonstrate the reliability of this system with respect to its ability to switch properly between redundant CPU. The total reliability estimation problem -- which considers the computer hardware, the operating system software, and the application software -- has been reduced to one that considers only the application software directly involved in the switchover process. Estimates are provided for software reliability and the testing coverage. Software and hardware reliability models and reliability growth models are considered in addition to Bayesian approaches.

  18. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    NASA Astrophysics Data System (ADS)

    Gharouni-Nik, Morteza; Naeimi, Meysam; Ahadi, Sodayf; Alimoradi, Zahra

    2014-06-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute to stability of the tunnel structure are recognized owing to identify various aspects of reliability and sustainability in the system. The selection of efficient support methods for rock tunneling is a key factor in order to reduce the number of problems during construction and maintain the project cost and time within the limited budget and planned schedule. This paper introduces a smart approach by which decision-makers will be able to find the overall reliability of tunnel support system before selecting the final scheme of the lining system. Due to this research focus, engineering reliability which is a branch of statistics and probability is being appropriately applied to the field and much effort has been made to use it in tunneling while investigating the reliability of the lining support system for the tunnel structure. Therefore, reliability analysis for evaluating the tunnel support performance is the main idea used in this research. Decomposition approaches are used for producing system block diagram and determining the failure probability of the whole system. Effectiveness of the proposed reliability model of tunnel lining together with the recommended approaches is examined using several case studies and the final value of reliability obtained for different designing scenarios. Considering the idea of linear correlation between safety factors and reliability parameters, the values of isolated reliabilities determined for different structural components of tunnel support system. In order to determine individual safety factors, finite element modeling is employed for different structural subsystems and the results of numerical analyses are obtained in

  19. The application of emulation techniques in the analysis of highly reliable, guidance and control computer systems

    NASA Technical Reports Server (NTRS)

    Migneault, Gerard E.

    1987-01-01

    Emulation techniques can be a solution to a difficulty that arises in the analysis of the reliability of guidance and control computer systems for future commercial aircraft. Described here is the difficulty, the lack of credibility of reliability estimates obtained by analytical modeling techniques. The difficulty is an unavoidable consequence of the following: (1) a reliability requirement so demanding as to make system evaluation by use testing infeasible; (2) a complex system design technique, fault tolerance; (3) system reliability dominated by errors due to flaws in the system definition; and (4) elaborate analytical modeling techniques whose precision outputs are quite sensitive to errors of approximation in their input data. Use of emulation techniques for pseudo-testing systems to evaluate bounds on the parameter values needed for the analytical techniques is then discussed. Finally several examples of the application of emulation techniques are described.

  20. Independent transmission system operators and their role in maintaining reliability in a restructured electric power industry

    SciTech Connect

    1998-01-01

    This report summarizes the current status of proposals to form Independent System Operators (ISOs) to operate high-voltage transmission systems in the United States and reviews their potential role in maintaining bulk power system reliability. As background information, the likely new industry structure, nature of deregulated markets, and institutional framework for bulk power system reliability are reviewed. The report identifies issues related to the formation of ISOs and their roles in markets and in reliability, and describes potential policy directions for encouraging the formation of effective ISOs and ensuring bulk system reliability. Two appendices are provided, which address: (1) system operation arrangements in other countries, and (2) summaries of regional U.S. ISO proposals.

  1. Reliability considerations of electronics components for the deep underwater muon and neutrino detection system

    SciTech Connect

    Leskovar, B.

    1980-02-01

    The reliability of some electronics components for the Deep Underwater Muon and Neutrino Detection (DUMAND) System is discussed. An introductory overview of engineering concepts and technique for reliability assessment is given. Component reliability is discussed in the contest of major factors causing failures, particularly with respect to physical and chemical causes, process technology and testing, and screening procedures. Failure rates are presented for discrete devices and for integrated circuits as well as for basic electronics components. Furthermore, the military reliability specifications and standards for semiconductor devices are reviewed.

  2. Reliability of the Advanced Psychodiagnostic Interpretation (API) Scoring System for the Bender Gestalt.

    ERIC Educational Resources Information Center

    Aucone, Ernest J.; Raphael, Alan J.; Golden, Charles J.; Espe-Pfeifer, Patricia; Seldon, Jen; Pospisil, Tanya; Dornheim, Liane; Proctor-Weber, Zoe; Calabria, Michael

    1999-01-01

    Assessed the interrater reliability of the revised Advanced Psychodiagnostic Interpretation (API) (A. Raphael and C. Golden, 1998) scoring system for the Bender Gestalt Test (L. Bender, 1938). Agreement across nine raters exceeded 90% for each of three clinical protocols, and kappa statistics indicated good interrater reliability. (SLD)

  3. 76 FR 16263 - Revision to Electric Reliability Organization Definition of Bulk Electric System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-03-23

    ... Energy Regulatory Commission 18 CFR Part 40 Revision to Electric Reliability Organization Definition of... Electric Reliability Organization (ERO) to revise the definition of the term ``bulk electric system... technical concerns and ensure that the definition encompasses all facilities necessary for operating...

  4. An immunological basis for high-reliability systems control.

    SciTech Connect

    Somayaji, Anil B.; Amai, Wendy A.; Walther, Eleanor A.

    2005-03-01

    This reports describes the successful extension of artificial immune systems from the domain of computer security to the domain of real time control systems for robotic vehicles. A biologically-inspired computer immune system was added to the control system of two different mobile robots. As an additional layer in a multi-layered approach, the immune system is complementary to traditional error detection and error handling techniques. This can be thought of as biologically-inspired defense in depth. We demonstrated an immune system can be added with very little application developer effort, resulting in little to no performance impact. The methods described here are extensible to any system that processes a sequence of data through a software interface.

  5. Survey and characterization of feedwater venture fouling at nuclear power plants

    SciTech Connect

    Allmon, W.E.; Sarver, L.W.; Boyce, S.L. . Contract Research Div.); Lamanna, L.S.; Lucero, V.A.; Koch, D.W. )

    1992-05-01

    Fouling of feedwater venturis in nuclear power generating plants was investigated by a survey of seven plants and by venturi inspections and deposit analyses at three plants. The information in this report will be useful to plant operators and chemists and to those involved in venturi manufacturing and calibration. Video inspection and SEM/EDS analyses show that deposits follow machining and polishing marks and that deposits accumulate on areas of abrupt flow transition. Also, corrosion of copper alloys downstream of the condensate polishers results in venturi fouling. The results indicate that feedwater venturi fouling can be minimized by (a) minimizing sharp flow transitions and turbulence within the venturis, (b) enhancing the surface smoothness, for example, by electropolishing, (c) minimizing copper-bearing alloys in the balance-of-plant, especially downstream of the condensate polishers, (d) minimizing exposure of the venturis to high concentrations of corrosion products during preoperational cleanup, and (e) minimizing the design velocity and/or pressure drop through the venturis. Alternate water chemistry, such as morpholine or other amines, for reducing venturi fouling was not investigated since most PWR plants had only recently converted to an alternate chemistry.

  6. System reliability assessment with an approximate reasoning model

    SciTech Connect

    Eisenhawer, S.W.; Bott, T.F.; Helm, T.M.; Boerigter, S.T.

    1998-12-31

    The projected service life of weapons in the US nuclear stockpile will exceed the original design life of their critical components. Interim metrics are needed to describe weapon states for use in simulation models of the nuclear weapons complex. The authors present an approach to this problem based upon the theory of approximate reasoning (AR) that allows meaningful assessments to be made in an environment where reliability models are incomplete. AR models are designed to emulate the inference process used by subject matter experts. The emulation is based upon a formal logic structure that relates evidence about components. This evidence is translated using natural language expressions into linguistic variables that describe membership in fuzzy sets. The authors introduce a metric that measures the acceptability of a weapon to nuclear deterrence planners. Implication rule bases are used to draw a series of forward chaining inferences about the acceptability of components, subsystems and individual weapons. They describe each component in the AR model in some detail and illustrate its behavior with a small example. The integration of the acceptability metric into a prototype model to simulate the weapons complex is also described.

  7. Energy efficiency and reliability in wireless biomedical implant systems.

    PubMed

    Abouei, Jamshid; Brown, J David; Plataniotis, Konstantinos N Kostas; Pasupathy, Subbarayan

    2011-05-01

    The use of wireless implant technology requires correct delivery of the vital physiological signs of the patient along with the energy management in power-constrained devices. Toward these goals, we present an augmentation protocol for the physical layer of the medical implant communications service (MICS) with focus on the energy efficiency of deployed devices over the MICS frequency band. The present protocol uses the rateless code with the frequency-shift keying (FSK) modulation scheme to overcome the reliability and power cost concerns in tiny implantable sensors due to the considerable attenuation of propagated signals across the human body. In addition, the protocol allows a fast start-up time for the transceiver circuitry. The main advantage of using rateless codes is to provide an inherent adaptive duty cycling for power management, due to the flexibility of the rateless code rate. Analytical results demonstrate that an 80% energy saving is achievable with the proposed protocol when compared to the IEEE 802.15.4 physical layer standard with the same structure used for wireless sensor networks. Numerical results show that the optimized rateless coded FSK is more energy efficient than that of the uncoded FSK scheme for deep tissue (e.g., digestive endoscopy) applications, where the optimization is performed over modulation and coding parameters.

  8. System Reliability Assessment for a Rock Tunnel with Multiple Failure Modes

    NASA Astrophysics Data System (ADS)

    Lü, Qing; Chan, Chin Loong; Low, Bak Kong

    2013-07-01

    This paper presents a practical procedure for assessing the system reliability of a rock tunnel. Three failure modes, namely, inadequate support capacity, excessive tunnel convergence, and insufficient rockbolt length, are considered and investigated using a deterministic model of ground-support interaction analysis based on the convergence-confinement method (CCM). The failure probability of each failure mode is evaluated from the first-order reliability method (FORM) and the response surface method (RSM) via an iterative procedure. The system failure probability bounds are estimated using the bimodal bounds approach suggested by Ditlevsen (1979), based on the reliability index and design point inferred from the FORM. The proposed approach is illustrated with an example of a circular rock tunnel. The computed system failure probability bounds compare favorably with those generated from Monte Carlo simulations. The results show that the relative importance of different failure modes to the system reliability of the tunnel mainly depends on the timing of support installation relative to the advancing tunnel face. It is also shown that reliability indices based on the second-order reliability method (SORM) can be used to achieve more accurate bounds on the system failure probability for nonlinear limit state surfaces. The system reliability-based design for shotcrete thickness is also demonstrated.

  9. Computer Aided Method for System Safety and Reliability Assessments

    DTIC Science & Technology

    2008-09-01

    instruction, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing the collection of information...aspects of safety within the constraints of operational effectiveness, time and cost throughout all phases of the system life cycle.” Often there...contributes to systems engineering objectives by applying a set of safety design requirements throughout all life cycle phases of a system, whether

  10. Report on the analysis of field data relating to the reliability of solar hot water systems.

    SciTech Connect

    Menicucci, David F.

    2011-07-01

    Utilities are overseeing the installations of thousand of solar hot water (SHW) systems. Utility planners have begun to ask for quantitative measures of the expected lifetimes of these systems so that they can properly forecast their loads. This report, which augments a 2009 reliability analysis effort by Sandia National Laboratories (SNL), addresses this need. Additional reliability data have been collected, added to the existing database, and analyzed. The results are presented. Additionally, formal reliability theory is described, including the bathtub curve, which is the most common model to characterize the lifetime reliability character of systems, and for predicting failures in the field. Reliability theory is used to assess the SNL reliability database. This assessment shows that the database is heavily weighted with data that describe the reliability of SHW systems early in their lives, during the warranty period. But it contains few measured data to describe the ends of SHW systems lives. End-of-life data are the most critical ones to define sufficiently the reliability of SHW systems in order to answer the questions that the utilities pose. Several ideas are presented for collecting the required data, including photometric analysis of aerial photographs of installed collectors, statistical and neural network analysis of energy bills from solar homes, and the development of simple algorithms to allow conventional SHW controllers to announce system failures and record the details of the event, similar to how aircraft black box recorders perform. Some information is also presented about public expectations for the longevity of a SHW system, information that is useful in developing reliability goals.

  11. Design and Analysis of a Flexible, Reliable Deep Space Life Support System

    NASA Technical Reports Server (NTRS)

    Jones, Harry W.

    2012-01-01

    This report describes a flexible, reliable, deep space life support system design approach that uses either storage or recycling or both together. The design goal is to provide the needed life support performance with the required ultra reliability for the minimum Equivalent System Mass (ESM). Recycling life support systems used with multiple redundancy can have sufficient reliability for deep space missions but they usually do not save mass compared to mixed storage and recycling systems. The best deep space life support system design uses water recycling with sufficient water storage to prevent loss of crew if recycling fails. Since the amount of water needed for crew survival is a small part of the total water requirement, the required amount of stored water is significantly less than the total to be consumed. Water recycling with water, oxygen, and carbon dioxide removal material storage can achieve the high reliability of full storage systems with only half the mass of full storage and with less mass than the highly redundant recycling systems needed to achieve acceptable reliability. Improved recycling systems with lower mass and higher reliability could perform better than systems using storage.

  12. Constellation Ground Systems Launch Availability Analysis: Enhancing Highly Reliable Launch Systems Design

    NASA Technical Reports Server (NTRS)

    Gernand, Jeffrey L.; Gillespie, Amanda M.; Monaghan, Mark W.; Cummings, Nicholas H.

    2010-01-01

    Success of the Constellation Program's lunar architecture requires successfully launching two vehicles, Ares I/Orion and Ares V/Altair, within a very limited time period. The reliability and maintainability of flight vehicles and ground systems must deliver a high probability of successfully launching the second vehicle in order to avoid wasting the on-orbit asset launched by the first vehicle. The Ground Operations Project determined which ground subsystems had the potential to affect the probability of the second launch and allocated quantitative availability requirements to these subsystems. The Ground Operations Project also developed a methodology to estimate subsystem reliability, availability, and maintainability to ensure that ground subsystems complied with allocated launch availability and maintainability requirements. The verification analysis developed quantitative estimates of subsystem availability based on design documentation, testing results, and other information. Where appropriate, actual performance history was used to calculate failure rates for legacy subsystems or comparative components that will support Constellation. The results of the verification analysis will be used to assess compliance with requirements and to highlight design or performance shortcomings for further decision making. This case study will discuss the subsystem requirements allocation process, describe the ground systems methodology for completing quantitative reliability, availability, and maintainability analysis, and present findings and observation based on analysis leading to the Ground Operations Project Preliminary Design Review milestone.

  13. Upper and lower bounds for semi-Markov reliability models of reconfigurable systems

    NASA Technical Reports Server (NTRS)

    White, A. L.

    1984-01-01

    This paper determines the information required about system recovery to compute the reliability of a class of reconfigurable systems. Upper and lower bounds are derived for these systems. The class consists of those systems that satisfy five assumptions: the components fail independently at a low constant rate, fault occurrence and system reconfiguration are independent processes, the reliability model is semi-Markov, the recovery functions which describe system configuration have small means and variances, and the system is well designed. The bounds are easy to compute, and examples are included.

  14. Multileaf collimator characteristics and reliability requirements for IMRT Elekta system.

    PubMed

    Liu, Chihray; Simon, Thomas A; Fox, Christopher; Li, Jonathan; Palta, Jatinder R

    2008-01-01

    Understanding the characteristics of a multileaf collimator (MLC) system, modeling MLC in a treatment planning system, and maintaining the mechanical accuracy of the linear accelerator gantry head system are important factors in the safe implementation of an intensity-modulated radiotherapy program. We review the characteristics of an Elekta MLC system, discuss the necessary MLC modeling parameters for a treatment planning system, and provide a novel method to establish an MLC leaf position quality assurance program. To perform quality assurance on 40 pairs of individual MLC leaves is a time-consuming and difficult task. In this report, an effective routine MLC quality assurance method based on the field edge of a backup jaw as referenced in conjunction with a diode array as a radiation detector system is discussed. The sensitivity of this test for determining the relative leaf positions was observed to be better than 0.1 mm. The Elekta MLC leaf position accuracy measured with this system has been better than 0.3 mm.

  15. Fisher Pierce products for improving distribution system reliability

    SciTech Connect

    1994-12-31

    The challenges facing the electric power utility today in the 1990s has changed significantly from those of even 10 years ago. The proliferation of automation and the personnel computer have heightened the requirements and demands put on the electric distribution system. Today`s customers, fighting to compete in a world market, demand quality, uninterrupted power service. Privatization and the concept of unregulated competition require utilities to streamline to minimize system support costs and optimize power delivery efficiency. Fisher Pierce, serving the electric utility industry for over 50 years, offers a line of products to assist utilities in meeting these challenges. The Fisher Pierce Family of products provide tools for the electric utility to exceed customer service demands. A full line of fault indicating devices are offered to expedite system power restoration both locally and in conjunction with SCADA systems. Fisher Pierce is the largest supplier of roadway lighting controls, manufacturing on a 6 million dollar automated line assuring the highest quality in the world. The distribution system capacitor control line offers intelligent local or radio linked switching control to maintain system voltage and Var levels for quality and cost efficient power delivery under varying customer loads. Additional products, designed to authenticate revenue metering calibration and verify on sight metering service wiring, help optimize the profitability of the utility assuring continuous system service improvements for their customers.

  16. Reliability review of the remote tool delivery system locomotor

    SciTech Connect

    Chesser, J.B.

    1999-04-01

    The locomotor being built by RedZone Robotics is designed to serve as a remote tool delivery (RID) system for waste retrieval, tank cleaning, viewing, and inspection inside the high-level waste tanks 8D-1 and 8D-2 at West Valley Nuclear Services (WVNS). The RTD systm is to be deployed through a tank riser. The locomotor portion of the RTD system is designed to be inserted into the tank and is to be capable of moving around the tank by supporting itself and moving on the tank internal structural columns. The locomotor will serve as a mounting platform for a dexterous manipulator arm. The complete RTD system consists of the locomotor, dexterous manipulator arm, cameras, lights, cables, hoses, cable/hose management system, power supply, and operator control station.

  17. A diameter-sensitive flow entropy method for reliability consideration in water distribution system design

    NASA Astrophysics Data System (ADS)

    Liu, Haixing; Savić, Dragan; Kapelan, Zoran; Zhao, Ming; Yuan, Yixing; Zhao, Hongbin

    2014-07-01

    Flow entropy is a measure of uniformity of pipe flows in water distribution systems. By maximizing flow entropy one can identify reliable layouts or connectivity in networks. In order to overcome the disadvantage of the common definition of flow entropy that does not consider the impact of pipe diameter on reliability, an extended definition of flow entropy, termed as diameter-sensitive flow entropy, is proposed. This new methodology is then assessed by using other reliability methods, including Monte Carlo Simulation, a pipe failure probability model, and a surrogate measure (resilience index) integrated with water demand and pipe failure uncertainty. The reliability assessment is based on a sample of WDS designs derived from an optimization process for each of the two benchmark networks. Correlation analysis is used to evaluate quantitatively the relationship between entropy and reliability. To ensure reliability, a comparative analysis between the flow entropy and the new method is conducted. The results demonstrate that the diameter-sensitive flow entropy shows consistently much stronger correlation with the three reliability measures than simple flow entropy. Therefore, the new flow entropy method can be taken as a better surrogate measure for reliability and could be potentially integrated into the optimal design problem of WDSs. Sensitivity analysis results show that the velocity parameters used in the new flow entropy has no significant impact on the relationship between diameter-sensitive flow entropy and reliability.

  18. 75 FR 61478 - Mandatory Reliability Standards for the Bulk Power System; Notice Allowing Post-Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Regulatory Commission conducted a Technical Conference on Frequency Response in the Wholesale Electric Grid... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Mandatory Reliability Standards for the Bulk Power System; Notice...

  19. Reliability Assessment of Reconfigurable Flight Control Systems Using Sure and Assist

    NASA Technical Reports Server (NTRS)

    Wu, N. Eva

    1992-01-01

    This paper presents a reliability assessment of Reconfigurable Flight Control Systems using Semi-Markov Unreliability Range Evaluator (SURE) and Abstract Semi-Markov Specification Interface to the SURE Tool (ASSIST).

  20. Reliability of the Koppitz scoring system for the Bender Gestalt Test.

    PubMed

    Hustak, T L; Dinning, W D; Andert, J N

    1976-04-01

    This study investigated the test-retest reliability of the Koppitz scoring system with Bender Gestalt protocols of adult retardates. Results of a sample of 74 adult retardates yielded a correlation of .80 over an interval of 8 to 146 months. A directional measure of change between error scores on the first and second administrations was not significant, which suggests that the test-retest reliability coefficient is an accurate estimate of the Koppitz scoring system for adult retardates. Scorer reliability for three independent scorers ranged from .92 to .95, which suggests comparability to other investigations with different populations.

  1. Reliability of EUCLIDIAN: An autonomous robotic system for image-guided prostate brachytherapy

    SciTech Connect

    Podder, Tarun K.; Buzurovic, Ivan; Huang Ke; Showalter, Timothy; Dicker, Adam P.; Yu, Yan

    2011-01-15

    Purpose: Recently, several robotic systems have been developed to perform accurate and consistent image-guided brachytherapy. Before introducing a new device into clinical operations, it is important to assess the reliability and mean time before failure (MTBF) of the system. In this article, the authors present the preclinical evaluation and analysis of the reliability and MTBF of an autonomous robotic system, which is developed for prostate seed implantation. Methods: The authors have considered three steps that are important in reliability growth analysis. These steps are: Identification and isolation of failures, classification of failures, and trend analysis. For any one-of-a-kind product, the reliability enhancement is accomplished through test-fix-test. The authors have used failure mode and effect analysis for collection and analysis of reliability data by identifying and categorizing the failure modes. Failures were classified according to severity. Failures that occurred during the operation of this robotic system were considered as nonhomogenous Poisson process. The failure occurrence trend was analyzed using Laplace test. For analyzing and predicting reliability growth, commonly used and widely accepted models, Duane's model and the Army Material Systems Analysis Activity, i.e., Crow's model, were applied. The MTBF was used as an important measure for assessing the system's reliability. Results: During preclinical testing, 3196 seeds (in 53 test cases) were deposited autonomously by the robot and 14 critical failures were encountered. The majority of the failures occurred during the first few cases. The distribution of failures followed Duane's postulation as well as Crow's postulation of reliability growth. The Laplace test index was -3.82 (<0), indicating a significant trend in failure data, and the failure intervals lengthened gradually. The continuous increase in the failure occurrence interval suggested a trend toward improved reliability. The MTBF

  2. Inspection reliability of a Nortec-30 Eddyscan system

    SciTech Connect

    Spencer, F.W.

    1994-01-01

    This report presents the results of an inspection around fastener holes in simulated lap splice specimens using a Nortec-30 Eddyscan inspection system. The inspector performing the tests had no prior knowledge of the extent or location of cracks in the specimens examined. The results of the inspection are presented in terms of various probability of detection curve models and are compared to various other eddy current inspections performed on the same set of test specimens. Results indicate that the system is capable, with high confidence, of detecting 60 to 70 mil cracks from under countersink fasteners.

  3. Software Technology for Adaptable, Reliable Systems (STARS) Program: SPMS Training Class: Student Handout. Addendum

    DTIC Science & Technology

    2015-04-02

    Sequence 03705-001B 30 September 1991 (3 SOFTWARE TECHNOLOGY FOR ADAPTABLE, RELIABLE SYSTEMS ( STARS ) PROGRAM ELEGTE m AUG15 1991 Ö I 0 SPMS Training...September 1991 SOFTWARE TECHNOLOGY FOR ADAPTABLE, RELIABLE SYSTEMS ( STARS ) PROGRAM SPMS Training Class: Student Handout Addendum to: Software...document is the student handout prepared for the "SEI/ STARS P.3 Asset Acquisition Sub-task" training class. The student handout covers basic aspects

  4. The B-747 flight control system maintenance and reliability data base for cost effectiveness tradeoff studies

    NASA Technical Reports Server (NTRS)

    1982-01-01

    Primary and automatic flight controls are combined for a total flight control reliability and maintenance cost data base using information from two previous reports and additional cost data gathered from a major airline. A comparison of the current B-747 flight control system effects on reliability and operating cost with that of a B-747 designed for an active control wing load alleviation system is provided.

  5. Tera-OP Reliable Intelligently Adaptive Processing System (TRIPS) Implementation

    DTIC Science & Technology

    2008-09-01

    ITs in a two-dimensional, wormhole -routed, 5x5 mesh topology. The OPN has separate control and data channels, and can deliver one 64-bit data operand...communicate through the secondary memory system, which is interconnected by the On-Chip Network (OCN). The OCN is a 4x10, wormhole -routed mesh network

  6. Reliability, Maintainability, and Performance Issues in Hydraulic System Design

    DTIC Science & Technology

    1977-06-01

    5 microns and mental situations, lower. Develop improved scraper seals. 3 - °• . ’ -. -\\ . - I - The results of the program evaluations for the three...8217V i j / /t TABLE OF CONTENTS Page * SUMMARY . . . . . . . . . . . . 3 w PREFACE . . . . . . . . . ............ 6 LIST OF ILLUSTRATIONS o o...17 2 .iydraulic Sul-system Problem Causal Factors .... 19 3 Generalized Comparison of Helicopter and Fixed- Wing Aircraft

  7. Reliability of EUCLIDIAN: An autonomous robotic system for image-guided prostate brachytherapy

    PubMed Central

    Podder, Tarun K.; Buzurovic, Ivan; Huang, Ke; Showalter, Timothy; Dicker, Adam P.; Yu, Yan

    2011-01-01

    Purpose: Recently, several robotic systems have been developed to perform accurate and consistent image-guided brachytherapy. Before introducing a new device into clinical operations, it is important to assess the reliability and mean time before failure (MTBF) of the system. In this article, the authors present the preclinical evaluation and analysis of the reliability and MTBF of an autonomous robotic system, which is developed for prostate seed implantation. Methods: The authors have considered three steps that are important in reliability growth analysis. These steps are: Identification and isolation of failures, classification of failures, and trend analysis. For any one-of-a-kind product, the reliability enhancement is accomplished through test-fix-test. The authors have used failure mode and effect analysis for collection and analysis of reliability data by identifying and categorizing the failure modes. Failures were classified according to severity. Failures that occurred during the operation of this robotic system were considered as nonhomogenous Poisson process. The failure occurrence trend was analyzed using Laplace test. For analyzing and predicting reliability growth, commonly used and widely accepted models, Duane’s model and the Army Material Systems Analysis Activity, i.e., Crow’s model, were applied. The MTBF was used as an important measure for assessing the system’s reliability. Results: During preclinical testing, 3196 seeds (in 53 test cases) were deposited autonomously by the robot and 14 critical failures were encountered. The majority of the failures occurred during the first few cases. The distribution of failures followed Duane’s postulation as well as Crow’s postulation of reliability growth. The Laplace test index was −3.82 (<0), indicating a significant trend in failure data, and the failure intervals lengthened gradually. The continuous increase in the failure occurrence interval suggested a trend toward improved

  8. Reliable and Affordable Control Systems Active Combustor Pattern Factor Control

    NASA Technical Reports Server (NTRS)

    McCarty, Bob; Tomondi, Chris; McGinley, Ray

    2004-01-01

    Active, closed-loop control of combustor pattern factor is a cooperative effort between Honeywell (formerly AlliedSignal) Engines and Systems and the NASA Glenn Research Center to reduce emissions and turbine-stator vane temperature variations, thereby enhancing engine performance and life, and reducing direct operating costs. Total fuel flow supplied to the engine is established by the speed/power control, but the distribution to individual atomizers will be controlled by the Active Combustor Pattern Factor Control (ACPFC). This system consist of three major components: multiple, thin-film sensors located on the turbine-stator vanes; fuel-flow modulators for individual atomizers; and control logic and algorithms within the electronic control.

  9. Compact Reliable Robust (CORE) Power System for Auxiliary Power Applications

    DTIC Science & Technology

    2009-08-17

    1,000 hour demonstration. This paper summarizes the results of Segment I and some of the activities of Segment II. The power system builds upon and...FPP removes sulfur and the majority of carbon -producing compounds in the fuel and diverts them to a burner to produce heat needed by the reformer...qualification activities are presented in Figure 2. Presented in Figure 2a are data from the qualification of the regenerable adsorbent that is

  10. Effective Measurement of Reliability of Repairable USAF Systems

    DTIC Science & Technology

    2012-09-01

    Under Secretary of Defense for Acquisition, Technology , and Logistics, Implementing a Lifecycle Mangement Framework, Washington DC, DC: DoD, 2008...USAF AFIT/GSE/ENV/12-S02DL DEPARTMENT OF THE AIR FORCE AIR UNIVERSITY AIR FORCE INSTITUTE OF TECHNOLOGY Wright-Patterson Air Force Base...Department of Systems and Engineering Management Graduate School of Engineering and Management Air Force Institute of Technology Air

  11. Software Technology for Adaptable, Reliable Systems (STARS) Program

    DTIC Science & Technology

    1993-07-31

    SPONSORING4MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORING I MONITORING AGENCY REPORT NUMBER Electronic Systems Center/ AVK Air Force Materiel Command...teamwork is now the normal mode of operation, and that people are excited about the software process being established and are motivated to produce high...Report CDRL 35503-004 Page 23 0 7. Recommendations Recommendations based on this work are made in three areas as follows: 1) Actions to support continued

  12. Workload, Performance and Reliability of Digital Computing Systems.

    DTIC Science & Technology

    1981-04-06

    available for general use and/or experimentation. And of the DDP systems available, 2 W (Vt.KLOAD, PERFORMANCE, AND RELIABI1LITY OF DIGITAL COMPUTING...being in one of several capacity states. This is a similar approach to the one previoulsy taken in [Beaudry 781, where the concept of "computation I...to the number of bugs present in the software at a given time during its development. Typical of this approach are the , , INTRODUCTION 7 models

  13. Use of Soft Computing Technologies for a Qualitative and Reliable Engine Control System for Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Trevino, Luis; Brown, Terry; Crumbley, R. T. (Technical Monitor)

    2001-01-01

    The problem to be addressed in this paper is to explore how the use of Soft Computing Technologies (SCT) could be employed to improve overall vehicle system safety, reliability, and rocket engine performance by development of a qualitative and reliable engine control system (QRECS). Specifically, this will be addressed by enhancing rocket engine control using SCT, innovative data mining tools, and sound software engineering practices used in Marshall's Flight Software Group (FSG). The principle goals for addressing the issue of quality are to improve software management, software development time, software maintenance, processor execution, fault tolerance and mitigation, and nonlinear control in power level transitions. The intent is not to discuss any shortcomings of existing engine control methodologies, but to provide alternative design choices for control, implementation, performance, and sustaining engineering, all relative to addressing the issue of reliability. The approaches outlined in this paper will require knowledge in the fields of rocket engine propulsion (system level), software engineering for embedded flight software systems, and soft computing technologies (i.e., neural networks, fuzzy logic, data mining, and Bayesian belief networks); some of which are briefed in this paper. For this effort, the targeted demonstration rocket engine testbed is the MC-1 engine (formerly FASTRAC) which is simulated with hardware and software in the Marshall Avionics & Software Testbed (MAST) laboratory that currently resides at NASA's Marshall Space Flight Center, building 4476, and is managed by the Avionics Department. A brief plan of action for design, development, implementation, and testing a Phase One effort for QRECS is given, along with expected results. Phase One will focus on development of a Smart Start Engine Module and a Mainstage Engine Module for proper engine start and mainstage engine operations. The overall intent is to demonstrate that by

  14. Wind energy Computerized Maintenance Management System (CMMS) : data collection recommendations for reliability analysis.

    SciTech Connect

    Peters, Valerie A.; Ogilvie, Alistair B.

    2012-01-01

    This report addresses the general data requirements for reliability analysis of fielded wind turbines and other wind plant equipment. The report provides a rationale for why this data should be collected, a list of the data needed to support reliability and availability analysis, and specific data recommendations for a Computerized Maintenance Management System (CMMS) to support automated analysis. This data collection recommendations report was written by Sandia National Laboratories to address the general data requirements for reliability analysis of operating wind turbines. This report is intended to help develop a basic understanding of the data needed for reliability analysis from a Computerized Maintenance Management System (CMMS) and other data systems. The report provides a rationale for why this data should be collected, a list of the data needed to support reliability and availability analysis, and specific recommendations for a CMMS to support automated analysis. Though written for reliability analysis of wind turbines, much of the information is applicable to a wider variety of equipment and analysis and reporting needs. The 'Motivation' section of this report provides a rationale for collecting and analyzing field data for reliability analysis. The benefits of this type of effort can include increased energy delivered, decreased operating costs, enhanced preventive maintenance schedules, solutions to issues with the largest payback, and identification of early failure indicators.

  15. Verification of Triple Modular Redundancy (TMR) Insertion for Reliable and Trusted Systems

    NASA Technical Reports Server (NTRS)

    Berg, Melanie; LaBel, Kenneth A.

    2016-01-01

    We propose a method for TMR insertion verification that satisfies the process for reliable and trusted systems. If a system is expected to be protected using TMR, improper insertion can jeopardize the reliability and security of the system. Due to the complexity of the verification process, there are currently no available techniques that can provide complete and reliable confirmation of TMR insertion. This manuscript addresses the challenge of confirming that TMR has been inserted without corruption of functionality and with correct application of the expected TMR topology. The proposed verification method combines the usage of existing formal analysis tools with a novel search-detect-and-verify tool. Field programmable gate array (FPGA),Triple Modular Redundancy (TMR),Verification, Trust, Reliability,

  16. Ultra High Performance, Highly Reliable, Numeric Intensive Processors and Systems

    DTIC Science & Technology

    1989-10-01

    to design high-performance DSP/IP systems using either off-the-shelf components or application specific integrated circuitry [ ASIC ]. -9 - HSDAL . ARO...are the chirp-z transform ( CZT ) [13] and (Rader’s) Prime Factor Transform (PFT) [11]. The RNS/ CZT is being studied by a group a MITRE [14] and is given...PFT RNS/CRNS/QRNS implementation has dynamic range requirements on the order of NQ2 (vs NQ4 for the CZT and much higher for the FFT). Therefore, the

  17. Development of a reliable transmission-based laser sensor system for intelligent transportation systems

    NASA Astrophysics Data System (ADS)

    Chowdhury, Mashrur A.; Banerjee, Partha; Nehmetallah, Georges; Goodhue, Paul C.; Das, Arobindu; Atluri, Mahesh

    2004-10-01

    The transportation community has applied sensors for various traffic management purposes, such as in traffic signal control, ramp metering, traveler information development, and incident detection by collecting and processing real-time vehicle position and speed. The U.S. transportation community has not adopted any single newer traffic detectors as the most accepted choice. The objective of this research is to develop an infrared sensor system in the laboratory that will provide improved estimates of vehicle speed compared to those available from current infrared sensors, to model the sensor"s failure conditions and probabilities, and ultimately refine the sensor to provide the most reliable data under various environmental conditions. This paper presents the initial development of the proposed sensor system. This system will be implemented in a highway segment to evaluate its the risks of failure under various environmental conditions. A modified design will then be developed based on the field evaluations.

  18. Efficient watermarking system with increased reliability for video authentication

    NASA Astrophysics Data System (ADS)

    Winne, Dominique A.; Knowles, Henry D.; Bull, David R.; Canagarajah, C. N.

    2003-06-01

    The widespread adoption of digital video techniques has generated a requirement for authenticity verification in applications such as criminal evidence, insurance claims and commercial databases. This paper extends our previous work and improves the watermark estimation procedure of a spatial digital video watermarking system designed to detect and characterize time-base attacks. Most watermark extraction processes utilize the noise masking levels of the image. These levels change during transmission, especially when the host signal is compressed at low bit-rates. The blocking artifacts that are introduced by this process modify the noise masking levels and influence the ability to form a good estimate of the embedded watermark. This paper describes a novel filter procedure to eliminate these artifacts from the noise masking levels. The efficiency is compared with the standard MPEG-4 deblocking and deringing filters. Extracting the watermark from only the encoded Macroblocks, excluding the skipped Macroblocks improves the performance significantly without an increase in computational complexity. The functionality of this system within an MPEG-4 implementation is demonstrated with a receiver operating characteristic.

  19. HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 3: HARP Graphics Oriented (GO) input user's guide

    NASA Technical Reports Server (NTRS)

    Bavuso, Salvatore J.; Rothmann, Elizabeth; Mittal, Nitin; Koppen, Sandra Howell

    1994-01-01

    The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of highly reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed at the outset to be compatible with most computing platforms and operating systems, and some programs have been beta tested within the aerospace community for over 8 years. This document is a user's guide for the HiRel graphical preprocessor Graphics Oriented (GO) program. GO is a graphical user interface for the HARP engine that enables the drawing of reliability/availability models on a monitor. A mouse is used to select fault tree gates or Markov graphical symbols from a menu for drawing.

  20. 76 FR 7187 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Reliability...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-09

    ... protecting against sophisticated and fast-moving threats? What role do you expect Smart Grid to play in the... grid reliability under Smart Grid applications? If not, how should NERC address these issues? c. Will Smart Grid applications have non-cyber reliability implications that need to be addressed? d. What...

  1. Digital Avionics Information System (DAIS): Reliability and Maintainability Model. Final Report.

    ERIC Educational Resources Information Center

    Czuchry, Andrew J.; And Others

    The reliability and maintainability (R&M) model described in this report represents an important portion of a larger effort called the Digital Avionics Information System (DAIS) Life Cycle Cost (LCC) Study. The R&M model is the first of three models that comprise a modeling system for use in LCC analysis of avionics systems. The total…

  2. Reliability model derivation of a fault-tolerant, dual, spare-switching, digital computer system

    NASA Technical Reports Server (NTRS)

    1974-01-01

    A computer based reliability projection aid, tailored specifically for application in the design of fault-tolerant computer systems, is described. Its more pronounced characteristics include the facility for modeling systems with two distinct operational modes, measuring the effect of both permanent and transient faults, and calculating conditional system coverage factors. The underlying conceptual principles, mathematical models, and computer program implementation are presented.

  3. A Sustainable, Reliable Mission-Systems Architecture that Supports a System of Systems Approach to Space Exploration

    NASA Technical Reports Server (NTRS)

    Watson, Steve; Orr, Jim; O'Neil, Graham

    2004-01-01

    A mission-systems architecture based on a highly modular "systems of systems" infrastructure utilizing open-standards hardware and software interfaces as the enabling technology is absolutely essential for an affordable and sustainable space exploration program. This architecture requires (a) robust communication between heterogeneous systems, (b) high reliability, (c) minimal mission-to-mission reconfiguration, (d) affordable development, system integration, and verification of systems, and (e) minimum sustaining engineering. This paper proposes such an architecture. Lessons learned from the space shuttle program are applied to help define and refine the model.

  4. Reliable Location-Based Services from Radio Navigation Systems

    PubMed Central

    Qiu, Di; Boneh, Dan; Lo, Sherman; Enge, Per

    2010-01-01

    Loran is a radio-based navigation system originally designed for naval applications. We show that Loran-C’s high-power and high repeatable accuracy are fantastic for security applications. First, we show how to derive a precise location tag—with a sensitivity of about 20 meters—that is difficult to project to an exact location. A device can use our location tag to block or allow certain actions, without knowing its precise location. To ensure that our tag is reproducible we make use of fuzzy extractors, a mechanism originally designed for biometric authentication. We build a fuzzy extractor specifically designed for radio-type errors and give experimental evidence to show its effectiveness. Second, we show that our location tag is difficult to predict from a distance. For example, an observer cannot predict the location tag inside a guarded data center from a few hundreds of meters away. As an application, consider a location-aware disk drive that will only work inside the data center. An attacker who steals the device and is capable of spoofing Loran-C signals, still cannot make the device work since he does not know what location tag to spoof. We provide experimental data supporting our unpredictability claim. PMID:22163532

  5. Reliable location-based services from radio navigation systems.

    PubMed

    Qiu, Di; Boneh, Dan; Lo, Sherman; Enge, Per

    2010-01-01

    Loran is a radio-based navigation system originally designed for naval applications. We show that Loran-C's high-power and high repeatable accuracy are fantastic for security applications. First, we show how to derive a precise location tag--with a sensitivity of about 20 meters--that is difficult to project to an exact location. A device can use our location tag to block or allow certain actions, without knowing its precise location. To ensure that our tag is reproducible we make use of fuzzy extractors, a mechanism originally designed for biometric authentication. We build a fuzzy extractor specifically designed for radio-type errors and give experimental evidence to show its effectiveness. Second, we show that our location tag is difficult to predict from a distance. For example, an observer cannot predict the location tag inside a guarded data center from a few hundreds of meters away. As an application, consider a location-aware disk drive that will only work inside the data center. An attacker who steals the device and is capable of spoofing Loran-C signals, still cannot make the device work since he does not know what location tag to spoof. We provide experimental data supporting our unpredictability claim.

  6. Resource allocation for reliability of a complex system with aging components

    SciTech Connect

    Anderson-cook, Christine M; Graves, Todd L; Hamada, Michael S

    2008-01-01

    To assess the reliability of a complex system, many different types of data may be available. Full-system tests are the most direct measure of reliability, but may be prohibitively expensive or difficult to obtain. Other less direct measures, such as component or section level tests, may be cheaper to obtain and more readily available. Using a single Bayesian analysis, multiple sources of data can be combined to give component and system reliability estimates. Resource allocation looks to develop methods to predict which new data would most improve the precision of the estimate of system reliability, in order to maximally improve understanding. In this paper, we consider a relatively simple system with different types of data from the components and system. We present a methodology for assessing the relative improvement in system reliability estimation for additional data from the various types. Various metrics for comparing improvement and a response surface approach to modeling the relationship between improvement and the additional data are presented.

  7. Reliability analysis of the electrical control system of subsea blowout preventers using Markov models.

    PubMed

    Liu, Zengkai; Liu, Yonghong; Cai, Baoping

    2014-01-01

    Reliability analysis of the electrical control system of a subsea blowout preventer (BOP) stack is carried out based on Markov method. For the subsea BOP electrical control system used in the current work, the 3-2-1-0 and 3-2-0 input voting schemes are available. The effects of the voting schemes on system performance are evaluated based on Markov models. In addition, the effects of failure rates of the modules and repair time on system reliability indices are also investigated.

  8. Reliability Analysis of the Electrical Control System of Subsea Blowout Preventers Using Markov Models

    PubMed Central

    Liu, Zengkai; Liu, Yonghong; Cai, Baoping

    2014-01-01

    Reliability analysis of the electrical control system of a subsea blowout preventer (BOP) stack is carried out based on Markov method. For the subsea BOP electrical control system used in the current work, the 3-2-1-0 and 3-2-0 input voting schemes are available. The effects of the voting schemes on system performance are evaluated based on Markov models. In addition, the effects of failure rates of the modules and repair time on system reliability indices are also investigated. PMID:25409010

  9. Event-triggered reliable control for fuzzy Markovian jump systems with mismatched membership functions.

    PubMed

    Hou, Liyuan; Cheng, Jun; Qi, Wenhai

    2017-01-01

    The problem of event-triggered reliable control for fuzzy Markovian jump system (FMJS) with mismatched membership functions (MMFs) is addressed. Based on the mode-dependent reliable control and event-triggered communication scheme, the stability conditions and control design procedure are formulated. More precisely, a general actuator-failure is designed such that the FMJS is reliable in the sense of stochastically stable and reduce the utilization of network resources. Furthermore, the improved MMFs are introduced to reduce the conservativeness of obtained results. Finally, simulation results indicate the effectiveness of the proposed methodology.

  10. Effect of system workload on operating system reliability - A study on IBM 3081

    NASA Technical Reports Server (NTRS)

    Iyer, R. K.; Rossetti, D. J.

    1985-01-01

    This paper presents an analysis of operating system failures on an IBM 3081 running VM/SP. Three broad categories of software failures are found: error handling, program control or logic, and hardware related; it is found that more than 25 percent of software failures occur in the hardware/software interface. Measurements show that results on software reliability cannot be considered representative unless the system workload is taken into account. The overall CPU execution rate, although measured to be close to 100 percent most of the time, is not found to correlate strongly with the occurrence of failures. Possible reasons for the observed workload failure dependency, based on detailed investigations of the failure data, are discussed.

  11. 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

  12. Data Applicability of Heritage and New Hardware for Launch Vehicle System Reliability Models

    NASA Technical Reports Server (NTRS)

    Al Hassan Mohammad; Novack, Steven

    2015-01-01

    Many launch vehicle systems are designed and developed using heritage and new hardware. In most cases, the heritage hardware undergoes modifications to fit new functional system requirements, impacting the failure rates and, ultimately, the reliability data. New hardware, which lacks historical data, is often compared to like systems when estimating failure rates. Some qualification of applicability for the data source to the current system should be made. Accurately characterizing the reliability data applicability and quality under these circumstances is crucial to developing model estimations that support confident decisions on design changes and trade studies. This presentation will demonstrate a data-source classification method that ranks reliability data according to applicability and quality criteria to a new launch vehicle. This method accounts for similarities/dissimilarities in source and applicability, as well as operating environments like vibrations, acoustic regime, and shock. This classification approach will be followed by uncertainty-importance routines to assess the need for additional data to reduce uncertainty.

  13. A Simple and Reliable Method of Design for Standalone Photovoltaic Systems

    NASA Astrophysics Data System (ADS)

    Srinivasarao, Mantri; Sudha, K. Rama; Bhanu, C. V. K.

    2016-08-01

    Standalone photovoltaic (SAPV) systems are seen as a promoting method of electrifying areas of developing world that lack power grid infrastructure. Proliferations of these systems require a design procedure that is simple, reliable and exhibit good performance over its life time. The proposed methodology uses simple empirical formulae and easily available parameters to design SAPV systems, that is, array size with energy storage. After arriving at the different array size (area), performance curves are obtained for optimal design of SAPV system with high amount of reliability in terms of autonomy at a specified value of loss of load probability (LOLP). Based on the array to load ratio (ALR) and levelized energy cost (LEC) through life cycle cost (LCC) analysis, it is shown that the proposed methodology gives better performance, requires simple data and is more reliable when compared with conventional design using monthly average daily load and insolation.

  14. A Survey of Techniques for Modeling and Improving Reliability of Computing Systems

    DOE PAGES

    Mittal, Sparsh; Vetter, Jeffrey S.

    2015-04-24

    Recent trends of aggressive technology scaling have greatly exacerbated the occurrences and impact of faults in computing systems. This has made `reliability' a first-order design constraint. To address the challenges of reliability, several techniques have been proposed. In this study, we provide a survey of architectural techniques for improving resilience of computing systems. We especially focus on techniques proposed for microarchitectural components, such as processor registers, functional units, cache and main memory etc. In addition, we discuss techniques proposed for non-volatile memory, GPUs and 3D-stacked processors. To underscore the similarities and differences of the techniques, we classify them based onmore » their key characteristics. We also review the metrics proposed to quantify vulnerability of processor structures. Finally, we believe that this survey will help researchers, system-architects and processor designers in gaining insights into the techniques for improving reliability of computing systems.« less

  15. A Survey of Techniques for Modeling and Improving Reliability of Computing Systems

    SciTech Connect

    Mittal, Sparsh; Vetter, Jeffrey S.

    2015-04-24

    Recent trends of aggressive technology scaling have greatly exacerbated the occurrences and impact of faults in computing systems. This has made `reliability' a first-order design constraint. To address the challenges of reliability, several techniques have been proposed. In this study, we provide a survey of architectural techniques for improving resilience of computing systems. We especially focus on techniques proposed for microarchitectural components, such as processor registers, functional units, cache and main memory etc. In addition, we discuss techniques proposed for non-volatile memory, GPUs and 3D-stacked processors. To underscore the similarities and differences of the techniques, we classify them based on their key characteristics. We also review the metrics proposed to quantify vulnerability of processor structures. Finally, we believe that this survey will help researchers, system-architects and processor designers in gaining insights into the techniques for improving reliability of computing systems.

  16. HiRel: Hybrid Automated Reliability Predictor (HARP) integrated reliability tool system, (version 7.0). Volume 4: HARP Output (HARPO) graphics display user's guide

    NASA Technical Reports Server (NTRS)

    Sproles, Darrell W.; Bavuso, Salvatore J.

    1994-01-01

    The Hybrid Automated Reliability Predictor (HARP) integrated Reliability (HiRel) tool system for reliability/availability prediction offers a toolbox of integrated reliability/availability programs that can be used to customize the user's application in a workstation or nonworkstation environment. HiRel consists of interactive graphical input/output programs and four reliability/availability modeling engines that provide analytical and simulative solutions to a wide host of highly reliable fault-tolerant system architectures and is also applicable to electronic systems in general. The tool system was designed at the outset to be compatible with most computing platforms and operating systems and some programs have been beta tested within the aerospace community for over 8 years. This document is a user's guide for the HiRel graphical postprocessor program HARPO (HARP Output). HARPO reads ASCII files generated by HARP. It provides an interactive plotting capability that can be used to display alternate model data for trade-off analyses. File data can also be imported to other commercial software programs.

  17. Reliability improvements of the Guri Hydroelectric Power Plant computer control system AGC and AVC

    SciTech Connect

    Castro, F.; Pescina, M. ); Llort, G. )

    1992-09-01

    This paper describes the computer control system of a large hydroelectric powerplant and the reliability improvements made to the automatic generation control (AGC) and automatic voltage control (AVC) programs. hardware and software modifications were required to improve the interface between the powerplant and the regional load dispatch office. These modifications, and their impact on the AGC and AVC reliability, are also discussed. The changes that have been implemented are recommended for inclusion in new powerplant computer control systems, and as an upgrade feature for existing control systems.

  18. Combining System Safety and Reliability to Ensure NASA CoNNeCT's Success

    NASA Technical Reports Server (NTRS)

    Havenhill, Maria; Fernandez, Rene; Zampino, Edward

    2012-01-01

    Hazard Analysis, Failure Modes and Effects Analysis (FMEA), the Limited-Life Items List (LLIL), and the Single Point Failure (SPF) List were applied by System Safety and Reliability engineers on NASA's Communications, Navigation, and Networking reConfigurable Testbed (CoNNeCT) Project. The integrated approach involving cross reviews of these reports by System Safety, Reliability, and Design engineers resulted in the mitigation of all identified hazards. The outcome was that the system met all the safety requirements it was required to meet.

  19. Structural system reliability calculation using a probabilistic fault tree analysis method

    NASA Technical Reports Server (NTRS)

    Torng, T. Y.; Wu, Y.-T.; Millwater, H. R.

    1992-01-01

    The development of a new probabilistic fault tree analysis (PFTA) method for calculating structural system reliability is summarized. The proposed PFTA procedure includes: developing a fault tree to represent the complex structural system, constructing an approximation function for each bottom event, determining a dominant sampling sequence for all bottom events, and calculating the system reliability using an adaptive importance sampling method. PFTA is suitable for complicated structural problems that require computer-intensive computer calculations. A computer program has been developed to implement the PFTA.

  20. Scaled CMOS Reliability and Considerations for Spacecraft Systems : Bottom-Up and Top-Down Perspectives

    NASA Technical Reports Server (NTRS)

    White, Mark

    2012-01-01

    The recently launched Mars Science Laboratory (MSL) flagship mission, named Curiosity, is the most complex rover ever built by NASA and is scheduled to touch down on the red planet in August, 2012 in Gale Crater. The rover and its instruments will have to endure the harsh environments of the surface of Mars to fulfill its main science objectives. Such complex systems require reliable microelectronic components coupled with adequate component and system-level design margins. Reliability aspects of these elements of the spacecraft system are presented from bottom- up and top-down perspectives.

  1. Reliability of the good balance system(®) for postural sway measurement in poststroke patients.

    PubMed

    Ha, Hyungeun; Cho, Kihun; Lee, Wanhee

    2014-01-01

    [Purpose] The purpose of this study was to examine test-retest reliability of the Good Balance system(®) for measurement of postural sway in poststroke patients. [Subjects] Sixty chronic stroke patients (40 men and 20 women; age 63.08 years; stroke duration 16.45 months) participated in this study. [Methods] Postural sway was evaluated using a force platform system (Good Balance system, Metitur Oy, Jyvaskyla, Finland). Two examiners measured postural sway for all participants during two separate testing sessions. The second measurement was performed one week after the first measurement. Intraclass correlation coefficients [ICC(2,1)] were used for estimation of reliability. [Results] The ICC (95% CI) for intra-examiner reliability was good to very good, ranging from 0.69 to 0.93 (0.53-0.96), and the ICC for inter-examiner reliability was good to very good, ranging from 0.85 to 0.98 (0.77-0.99). [Conclusion] The results of the current study indicated that the intra- and inter-examiner reliability of the Good Balance system(®) for measurement of postural sway was good to very good. Therefore, we suggest that measurement of postural sway using the Good Balance system(®) would be useful for clinical assessment in poststroke patients.

  2. Potentialities of theoretical and experimental prediction of Life Support Systems reliability.

    PubMed

    Bartsev, S I; Okhonin, V A

    1999-01-01

    To develop and design Life Support Systems it is necessary to evaluate their reliability. However direct experiments take much time, are very expensive, and therefore are practically impossible. Promising way is to use approximate estimates of reliability, which need essentially fewer amounts of experimental data. Two types of estimates of Life Support System reliability--additive and multiplicative ones are considered in the paper. Additive estimate is based on the assumption that total system failure probability is low and therefore it can be considered as the sum of failure probability of separate units. Additive approach allows obtaining near lower-bounded estimate of failure probability. Multiplicative estimate allows evaluating the possibility of system catastrophe due to simultaneous effect of several factors when each of them separately is not dangerous. Evaluation shows that the possible error of reliability forecast increases with the increasing of number of external factors faster than exponential function. An illustration of the ecological similarity approach as promising tool for providing estimation of full-scale system reliability by means the set of small similar experimental models.

  3. Non-probabilistic stability reliability measure for active vibration control system with interval parameters

    NASA Astrophysics Data System (ADS)

    Li, Yunlong; Wang, Xiaojun; Wang, Lei; Fan, Weichao; Qiu, Zhiping

    2017-01-01

    A systematic non-probabilistic reliability analysis procedure for structural vibration active control system with unknown-but-bounded parameters is proposed. The state-space representation of active vibration control system with uncertain parameters is presented. Compared with the robust control theory, which is always over-conservative, the reliability-based analysis method is more suitable to deal with uncertain problem. Stability is the core of the closed-loop feedback control system design, so stability criterion is adopted to act as the limited state function for reliability analysis. The uncertain parameters without enough samples are modeled as interval variables. Interval perturbation method is employed to estimate the interval bounds of eigenvalues, which can be used to characterize the stability of the closed-loop active control system. Formulation of defining the reliability of active control system based on stability is discussed. A novel non-probabilistic reliability measurement index is discussed and used to determine the probability of the stability based on the area ratio. The feasibility and efficiency of the proposed method are demonstrated by two numerical examples.

  4. Reliability Analysis of a Glacier Lake Warning System Using a Bayesian Net

    NASA Astrophysics Data System (ADS)

    Sturny, Rouven A.; Bründl, Michael

    2013-04-01

    Beside structural mitigation measures like avalanche defense structures, dams and galleries, warning and alarm systems have become important measures for dealing with Alpine natural hazards. Integrating them into risk mitigation strategies and comparing their effectiveness with structural measures requires quantification of the reliability of these systems. However, little is known about how reliability of warning systems can be quantified and which methods are suitable for comparing their contribution to risk reduction with that of structural mitigation measures. We present a reliability analysis of a warning system located in Grindelwald, Switzerland. The warning system was built for warning and protecting residents and tourists from glacier outburst floods as consequence of a rapid drain of the glacier lake. We have set up a Bayesian Net (BN, BPN) that allowed for a qualitative and quantitative reliability analysis. The Conditional Probability Tables (CPT) of the BN were determined according to manufacturer's reliability data for each component of the system as well as by assigning weights for specific BN nodes accounting for information flows and decision-making processes of the local safety service. The presented results focus on the two alerting units 'visual acoustic signal' (VAS) and 'alerting of the intervention entities' (AIE). For the summer of 2009, the reliability was determined to be 94 % for the VAS and 83 % for the AEI. The probability of occurrence of a major event was calculated as 0.55 % per day resulting in an overall reliability of 99.967 % for the VAS and 99.906 % for the AEI. We concluded that a failure of the VAS alerting unit would be the consequence of a simultaneous failure of the four probes located in the lake and the gorge. Similarly, we deduced that the AEI would fail either if there were a simultaneous connectivity loss of the mobile and fixed network in Grindelwald, an Internet access loss or a failure of the regional operations

  5. Reliability assessment of power distribution systems using disjoint path-set algorithm

    NASA Astrophysics Data System (ADS)

    Bourezg, Abdrabbi; Meglouli, H.

    2015-10-01

    Finding the reliability expression of different substation configurations can help design a distribution system with the best overall reliability. This paper presents a computerized a nd implemented algorithm, based on Disjoint Sum of Product (DSOP) algorithm. The algorithm was synthesized and applied for the first time to the determination of reliability expression of a substation to determine reliability indices and costs of different substation arrangements. It deals with the implementation and synthesis of a new designed algorithm for DSOP implemented using C/C++, incorporating parallel problem solving capability and overcoming the disadvantage of Monte Carlo simulation which is the lengthy computational time to achieve satisfactory statistical convergence of reliability index values. The major highlight of this research being that the time consuming procedures of the DSOP solution generated for different substation arrangements using the proposed method is found to be significantly lower in comparison with the time consuming procedures of Monte Carlo-simulation solution or any other method used for the reliability evaluation of substations in the existing literature such as meta-heuristic and soft computing algorithms. This implementation gives the possibility of RBD simulation for different substation configurations in C/C++ using their path-set Boolean expressions mapped to probabilistic domain and result in simplest Sum of Disjoint Product which is on a one-to-one correspondence with reliability expression. This software tool is capable of handling and modeling a large, repairable system. Additionally, through its intuitive interface it can be easily used for industrial and commercial power systems. With simple Boolean expression for a configuration's RBD inputted, users can define a power system utilizing a RBD and, through a fast and efficient built-in simulation engine, the required reliability expressions and indices can be obtained. Two case studies

  6. 48 CFR 1852.246-70 - Mission Critical Space System Personnel Reliability Program.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 48 Federal Acquisition Regulations System 6 2010-10-01 2010-10-01 true Mission Critical Space... CONTRACT CLAUSES Texts of Provisions and Clauses 1852.246-70 Mission Critical Space System Personnel Reliability Program. As prescribed in 1846.370(a), insert the following clause: Mission Critical Space...

  7. Reliability-economics analysis models for photovoltaic power systems. Volume 1

    SciTech Connect

    Stember, L.H.; Huss, W.R.; Bridgman, M.S.

    1982-11-01

    This report describes the development of modeling techniques to characterize the reliability, availability, and maintenance costs of photovoltaic power systems. The developed models can be used by designers of PV systems in making design decisions and trade-offs to minimize life-cycle energy costs.

  8. Perceptual and Acoustic Reliability Estimates for the Speech Disorders Classification System (SDCS)

    ERIC Educational Resources Information Center

    Shriberg, Lawrence D.; Fourakis, Marios; Hall, Sheryl D.; Karlsson, Heather B.; Lohmeier, Heather L.; McSweeny, Jane L.; Potter, Nancy L.; Scheer-Cohen, Alison R.; Strand, Edythe A.; Tilkens, Christie M.; Wilson, David L.

    2010-01-01

    A companion paper describes three extensions to a classification system for paediatric speech sound disorders termed the Speech Disorders Classification System (SDCS). The SDCS uses perceptual and acoustic data reduction methods to obtain information on a speaker's speech, prosody, and voice. The present paper provides reliability estimates for…

  9. Validation of highly reliable, real-time knowledge-based systems

    NASA Technical Reports Server (NTRS)

    Johnson, Sally C.

    1988-01-01

    Knowledge-based systems have the potential to greatly increase the capabilities of future aircraft and spacecraft and to significantly reduce support manpower needed for the space station and other space missions. However, a credible validation methodology must be developed before knowledge-based systems can be used for life- or mission-critical applications. Experience with conventional software has shown that the use of good software engineering techniques and static analysis tools can greatly reduce the time needed for testing and simulation of a system. Since exhaustive testing is infeasible, reliability must be built into the software during the design and implementation phases. Unfortunately, many of the software engineering techniques and tools used for conventional software are of little use in the development of knowledge-based systems. Therefore, research at Langley is focused on developing a set of guidelines, methods, and prototype validation tools for building highly reliable, knowledge-based systems. The use of a comprehensive methodology for building highly reliable, knowledge-based systems should significantly decrease the time needed for testing and simulation. A proven record of delivering reliable systems at the beginning of the highly visible testing and simulation phases is crucial to the acceptance of knowledge-based systems in critical applications.

  10. 76 FR 2369 - Priorities for Addressing Risks to the Reliability of the Bulk-Power System; Notice of Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-13

    ... Energy Regulatory Commission Priorities for Addressing Risks to the Reliability of the Bulk- Power System... related to reliability of the Bulk-Power System, including priorities for addressing risks to reliability.... The conference will be Webcast. Anyone with Internet access who desires to listen to this event can...

  11. Feasibility and Reliability of a Coding System to Capture In-Session Group Behavior in Adolescents.

    PubMed

    Ladd, Benjamin O; Tomlinson, Kristin; Myers, Mark G; Anderson, Kristen G

    2016-01-01

    Limited research has explored the role of in-session behavior during motivational enhancement (ME) in group formats. The current study presents initial feasibility of assessing behavior of high school students (N = 425) attending Project Options, a voluntary secondary drug and alcohol prevention program utilizing ME techniques. Building on previous research exploring client language supporting/opposing health behavior, student group behavior was coded live at the specific utterance and global level; group leader behavior was also coded globally. Interrater reliability of the coding system was assessed, and preliminary validity of the coding system was examined by exploring associations between characteristics of group members and in-session group behavior. Initial reliability estimates were excellent for the specific behavior codes. Reliability of the global codes was mixed, with raters demonstrating good reliability on support for unhealthy behavior, opposition to unhealthy behavior, and support for healthy behavior. Reliability of the group leader codes was fair to poor. Greater percent healthy talk was associated with a lower percentage of group members reporting lifetime alcohol use. The results of the current study suggest that some in-session behavior at the group level can be coded reliably via live observation and that in-session behavior at the group level is associated with alcohol use prior to attending the program. Future research is needed to explore the utility of in-session behavior in terms of predicting future behavior at the group and individual level.

  12. Feasibility and Reliability of a Coding System to Capture In-Session Group Behavior in Adolescents

    PubMed Central

    Tomlinson, Kristin; Myers, Mark G.; Anderson, Kristen G.

    2016-01-01

    Limited research has explored the role of in-session behavior during motivational enhancement (ME) in group formats. The current study presents initial feasibility of assessing behavior of high school students (N=425) attending Project Options, a voluntary secondary drug and alcohol prevention program utilizing ME techniques. Building on previous research exploring client language supporting/opposing health behavior, student group behavior was coded live at the specific utterance and global level; group leader behavior was also coded globally. Interrater reliability of the coding system was assessed, and preliminary validity of the coding system was examined by exploring associations between characteristics of group members and in-session group behavior. Initial reliability estimates were excellent for the specific behavior codes. Reliability of the global codes was mixed, with raters demonstrating good reliability on support for unhealthy behavior, opposition to unhealthy behavior, and support for healthy behavior. Reliability of the group leader codes was fair to poor. Greater percent healthy talk was associated with a lower percentage of group members reporting lifetime alcohol use. The results of the current study suggest that some in-session behavior at the group level can be coded reliably via live observation and that in-session behavior at the group level is associated with alcohol use prior to attending the program. Future research is needed to explore the utility of in-session behavior in terms of predicting future behavior at the group and individual level. PMID:26271299

  13. Reliable gain-scheduled control of discrete-time systems and its application to CSTR model

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Selvi, S.; Mathiyalagan, K.; Shi, Y.

    2016-10-01

    This paper is focused on reliable gain-scheduled controller design for a class of discrete-time systems with randomly occurring nonlinearities and actuator fault. Further, the nonlinearity in the system model is assumed to occur randomly according to a Bernoulli distribution with measurable time-varying probability in real time. The main purpose of this paper is to design a gain-scheduled controller by implementing a probability-dependent Lyapunov function and linear matrix inequality (LMI) approach such that the closed-loop discrete-time system is stochastically stable for all admissible randomly occurring nonlinearities. The existence conditions for the reliable controller is formulated in terms of LMI constraints. Finally, the proposed reliable gain-scheduled control scheme is applied on continuously stirred tank reactor model to demonstrate the effectiveness and applicability of the proposed design technique.

  14. ReSCo: A Middleware Component for Reliable Service Composition in Pervasive Systems

    SciTech Connect

    Lagesse, Brent J; Kumar, Mohan; Wright, Matthew

    2010-01-01

    Service composition schemes create high-level application services by combining several basic services. Service composition schemes for dynamic, open systems, such as those found in pervasive environments, must be cognizant of the possibility of failures and attacks. In open systems, it is seldom feasible to guarantee the reliability of each node prior to access; however, there may be several possible ways to compose the same high-level service, each having a different (though possibly overlapping) set of nodes that can satisfy the composition. We approach this problem with a Reliable Service Composition middleware component, ReSCo, to determine trustworthy compositions and nodes for service composition in dynamic, open systems. ReSCo is a modular, adaptive middleware component that selects from possible composition paths and nodes to enhance reliability of service compositions. ReSCo can work with a broad range of both service composition algorithms and trust establishment mechanisms.

  15. Department of Defense need for a micro-electromechanical systems (MEMS) reliability assessment program

    NASA Astrophysics Data System (ADS)

    Zunino, James L., III; Skelton, Donald

    2005-01-01

    As the United States (U.S.) Army transforms into a lighter, more lethal, and more agile force, the technologies that support both legacy and emerging weapon systems must decrease in size while increasing in intelligence. Micro-electromechanical systems (MEMS) are one such technology that the Army as well as entire DOD will heavily rely on in achieving these objectives. Current and future military applications of MEMS devices include safety and arming devices, guidance systems, sensors/detectors, inertial measurement units, tracking devices, radio frequency devices, wireless radio frequency identification (RFID), etc. Even though the reliance on MEMS devices has been increasing, there have been no studies performed to determine their reliability and failure mechanisms. Furthermore, no standardized test protocols exist for assessing reliability. Accordingly, the U.S. Army Corrosion Office at Picatinny, NJ has initiated the MEMS Reliability Assessment Program to address this issue.

  16. Department of Defense need for a micro-electromechanical systems (MEMS) reliability assessment program

    NASA Astrophysics Data System (ADS)

    Zunino, James L., III; Skelton, Donald

    2004-12-01

    As the United States (U.S.) Army transforms into a lighter, more lethal, and more agile force, the technologies that support both legacy and emerging weapon systems must decrease in size while increasing in intelligence. Micro-electromechanical systems (MEMS) are one such technology that the Army as well as entire DOD will heavily rely on in achieving these objectives. Current and future military applications of MEMS devices include safety and arming devices, guidance systems, sensors/detectors, inertial measurement units, tracking devices, radio frequency devices, wireless radio frequency identification (RFID), etc. Even though the reliance on MEMS devices has been increasing, there have been no studies performed to determine their reliability and failure mechanisms. Furthermore, no standardized test protocols exist for assessing reliability. Accordingly, the U.S. Army Corrosion Office at Picatinny, NJ has initiated the MEMS Reliability Assessment Program to address this issue.

  17. Reliability assessment of water supply systems with storage and distribution networks

    NASA Astrophysics Data System (ADS)

    Fujiwara, Okitsugu; Ganesharajah, Tharmarajah

    1993-08-01

    The water supply system studied in this paper consists of a water treatment plant, a ground-level storage, a pumping station, and a distribution network in series. Expected served demand is employed to measure reliability taking into account both insufficient heads and flows at individual nodes in the network since it is the most important service level index provided to individual users. A basic method proposed is to assume that the insufficient nodal head reduces the effectiveness of flow supplied at the node and that the authority provides the maximum service to customers so that the real-time pump and network flow operations maximize the effective served system demand. The average value of the maximum effective served system demand relative to the total system demand over all system states is defined as system reliability, and the nodal reliability for each demand node is similarly defined. The Markov chain method introduced by Beim and Hobbs (1988) is employed to describe the evolution of the storage level over time so that the real-time pump and network flow operations can be accurately implemented by solving a nonlinear programming model. Two example systems are presented to demonstrate numerically the advantage of the method proposed in its consideration of the distribution network and nodal reliabilities.

  18. Assembly and comparison of available solar hot water system reliability databases and information.

    SciTech Connect

    Menicucci, David F.

    2009-05-01

    Solar hot water (SHW) systems have been installed commercially for over 30 years, yet few quantitative details are known about their reliability. This report describes a comprehensive analysis of all of the known major previous research and data regarding the reliability of SHW systems and components. Some important conclusions emerged. First, based on a detailed inspection of ten-year-old systems in Florida, about half of active systems can be expected to fail within a ten-year period. Second, valves were identified as the probable cause of a majority of active SHW failures. Third, passive integral and thermosiphon SHW systems have much lower failure rates than active ones, probably due to their simple design that employs few mechanical parts. Fourth, it is probable that the existing data about reliability do not reveal the full extent of fielded system failures because most of the data were based on trouble calls. Often an SHW system owner is not aware of a failure because the backup system silently continues to produce hot water. Thus, a repair event may not be generated in a timely manner, if at all. This final report for the project provides all of the pertinent details about this study, including the source of the data, the techniques to assure their quality before analysis, the organization of the data into perhaps the most comprehensive reliability database in existence, a detailed statistical analysis, and a list of recommendations for additional critical work. Important recommendations include the inclusion of an alarm on SHW systems to identify a failed system, the need for a scientifically designed study to collect high-quality reliability data that will lead to design improvements and lower costs, and accelerated testing of components that are identified as highly problematic.

  19. 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

  20. Reliability, energy, and cost effects of wind-powered generation integrated with a conventional generating system

    SciTech Connect

    VanKuiken, J.C.; Buehring, W.A.; Huber, C.C.; Hub, K.A.

    1980-01-01

    The purpose of this investigation is to examine the potential impacts of incorporating wind turbines, without the aid of energy-storage devices, into a conventional electrical generating system. This study focuses on the contribution to generating-system reliability of wind turbines, and the methods used to calculate these benefits. In addition, a simple cost model was developed to estimate ranges of breakeven costs for wind turbines based on the sum of fuel cost savings, variable operation and maintenance (0 and M) cost savings, and reliability benefits of the wind turbines.

  1. Research on Air Traffic Control Automatic System Software Reliability Based on Markov Chain

    NASA Astrophysics Data System (ADS)

    Wang, Xinglong; Liu, Weixiang

    Ensuring the space of air craft and high efficiency of air traffic are the main job tasks of the air traffic control automatic system. An Air Traffic Control Automatic System (ATCAS) and Markov model is put forward in this paper, which collected the 36 month failure data of ATCAS; A method to predict the s1,s2,s3 of ATCAS is based on Markov chain which predicts and validates the Reliability of ATCTS according to the deriving theory of Reliability. The experimental results show that the method can be used for the future research and proved to be practicable.

  2. Small numbers, disclosure risk, security, and reliability issues in Web-based data query systems.

    PubMed

    Rudolph, Barbara A; Shah, Gulzar H; Love, Denise

    2006-01-01

    This article describes the process for developing consensus guidelines and tools for releasing public health data via the Web and highlights approaches leading agencies have taken to balance disclosure risk with public dissemination of reliable health statistics. An agency's choice of statistical methods for improving the reliability of released data for Web-based query systems is based upon a number of factors, including query system design (dynamic analysis vs preaggregated data and tables), population size, cell size, data use, and how data will be supplied to users. The article also describes those efforts that are necessary to reduce the risk of disclosure of an individual's protected health information.

  3. Mathematic Modeling of Complex Hydraulic Machinery Systems When Evaluating Reliability Using Graph Theory

    NASA Astrophysics Data System (ADS)

    Zemenkova, M. Yu; Shipovalov, A. N.; Zemenkov, Yu D.

    2016-04-01

    The main technological equipment of pipeline transport of hydrocarbons are hydraulic machines. During transportation of oil mainly used of centrifugal pumps, designed to work in the “pumping station-pipeline” system. Composition of a standard pumping station consists of several pumps, complex hydraulic piping. The authors have developed a set of models and algorithms for calculating system reliability of pumps. It is based on the theory of reliability. As an example, considered one of the estimation methods with the application of graph theory.

  4. Advanced Reactor Passive System Reliability Demonstration Analysis for an External Event

    SciTech Connect

    Bucknor, Matthew D.; Grabaskas, David; Brunett, Acacia J.; Grelle, Austin

    2016-01-01

    Many advanced reactor designs rely on passive systems to fulfill safety functions during accident sequences. These systems depend heavily on boundary conditions to induce a motive force, meaning the system can fail to operate as intended due to deviations in boundary conditions, rather than as the result of physical failures. Furthermore, passive systems may operate in intermediate or degraded modes. These factors make passive system operation difficult to characterize within a traditional probabilistic framework that only recognizes discrete operating modes and does not allow for the explicit consideration of time-dependent boundary conditions. Argonne National Laboratory has been examining various methodologies for assessing passive system reliability within a probabilistic risk assessment for a station blackout event at an advanced small modular reactor. This paper provides an overview of a passive system reliability demonstration analysis for an external event. Centering on an earthquake with the possibility of site flooding, the analysis focuses on the behavior of the passive reactor cavity cooling system following potential physical damage and system flooding. The assessment approach seeks to combine mechanistic and simulation-based methods to leverage the benefits of the simulation-based approach without the need to substantially deviate from conventional probabilistic risk assessment techniques. While this study is presented as only an example analysis, the results appear to demonstrate a high level of reliability for the reactor cavity cooling system (and the reactor system in general) to the postulated transient event.

  5. Boiler control systems engineering

    SciTech Connect

    Gilman, J.

    2005-07-01

    The book provides in-depth coverage on how to safely and reliably control the firing of a boiler. Regardless of the capacity or fuel, certain fundamental control systems are required for boiler control. Large utility systems are more complex due to the number of burners and the overall capacity and equipment. This book covers engineering details on control systems and provides specific examples of boiler control including configuration and tuning. References to requirements are based on the 2004 NFPA 85 along with other ISA standards. Detailed chapters cover: Boiler fundamentals including piping and instrument diagrams (P&IDs) and a design basis checklist; Control of boilers, from strategies and bumpless transfer to interlock circuitry and final control elements; Furnace draft; Feedwater; Coal-fired boilers; Fuel and air control; Steam temperature; Burner management systems; Environment; and Control valve sizing. 2 apps.

  6. Competing risk models in reliability systems, a weibull distribution model with bayesian analysis approach

    NASA Astrophysics Data System (ADS)

    Iskandar, Ismed; Satria Gondokaryono, Yudi

    2016-02-01

    In reliability theory, the most important problem is to determine the reliability of a complex system from the reliability of its components. The weakness of most reliability theories is that the systems are described and explained as simply functioning or failed. In many real situations, the failures may be from many causes depending upon the age and the environment of the system and its components. Another problem in reliability theory is one of estimating the parameters of the assumed failure models. The estimation may be based on data collected over censored or uncensored life tests. In many reliability problems, the failure data are simply quantitatively inadequate, especially in engineering design and maintenance system. The Bayesian analyses are more beneficial than the classical one in such cases. The Bayesian estimation analyses allow us to combine past knowledge or experience in the form of an apriori distribution with life test data to make inferences of the parameter of interest. In this paper, we have investigated the application of the Bayesian estimation analyses to competing risk systems. The cases are limited to the models with independent causes of failure by using the Weibull distribution as our model. A simulation is conducted for this distribution with the objectives of verifying the models and the estimators and investigating the performance of the estimators for varying sample size. The simulation data are analyzed by using Bayesian and the maximum likelihood analyses. The simulation results show that the change of the true of parameter relatively to another will change the value of standard deviation in an opposite direction. For a perfect information on the prior distribution, the estimation methods of the Bayesian analyses are better than those of the maximum likelihood. The sensitivity analyses show some amount of sensitivity over the shifts of the prior locations. They also show the robustness of the Bayesian analysis within the range

  7. Reliability studies of incident coding systems in high hazard industries: A narrative review of study methodology.

    PubMed

    Olsen, Nikki S

    2013-03-01

    This paper reviews the current literature on incident coding system reliability and discusses the methods applied in the conduct and measurement of reliability. The search strategy targeted three electronic databases using a list of search terms and the results were examined for relevance, including any additional relevant articles from the bibliographies. Twenty five papers met the relevance criteria and their methods are discussed. Disagreements in the selection of methods between reliability researchers are highlighted as are the effects of method selection on the outcome of the trials. The review provides evidence that the meaningfulness of and confidence in results is directly affected by the methodologies employed by the researcher during the preparation, conduct and analysis of the reliability study. Furthermore, the review highlights the heterogeneity of methodologies employed by researchers measuring reliability of incident coding techniques, reducing the ability to critically compare and appraise techniques being considered for the adoption of report coding and trend analysis by client organisations. It is recommended that future research focuses on the standardisation of reliability research and measurement within the incident coding domain.

  8. Assessing Changes in the Reliability of the U.S. Electric Power System

    SciTech Connect

    Larsen, Peter H.; LaCommare, Kristina H.; Eto, Joseph H.; Sweeney, James L.

    2015-08-01

    Over the past 15 years, the most well-publicized efforts to assess trends in U.S. electric power system reliability have focused only on a subset of all power interruption events (see, for example, Amin 2008 and Campbell 2012)—namely, only the very largest events, which trigger immediate emergency reporting to federal agencies and industry regulators. Anecdotally, these events are thought by many to represent no more than 10% of the power interruptions experienced annually by electricity consumers. Moreover, a review of these emergency reports has identified shortcomings in relying on these data as reliable sources for assessing trends, even with the reliability events they report (Fisher et al. 2012). Recent work has begun to address these limitations by examining trends in reliability data collected annually by electricity distribution companies (Eto et al. 2012). In principle, all power interruptions experienced by electricity customers, regardless of size, are recorded by the distribution utility. Moreover, distribution utilities have a long history of recording this information, often in response to mandates from state public utility commissions (Eto et al. 2006). Thus, studies that rely on reliability data collected by distribution utilities can, in principle, provide a more complete basis upon which to assess trends or changes in reliability over time.

  9. Reliable Magnetic Resonance Imaging Based Grading System for Cervical Intervertebral Disc Degeneration

    PubMed Central

    Chen, Antonia F.; Kang, James D.; Lee, Joon Y.

    2016-01-01

    Study Design Observational. Purpose To develop a simple and comprehensive grading system for cervical discs that precisely, consistently and meaningfully presents radiologic and morphologic data. Overview of Literature The Thompson grading system is commonly used to classify the severity of degenerative lumbar discs on magnetic resonance imaging (MRI). Inherent differences in the morphological and physiological characteristics of cervical discs have hindered development of precise classification systems. Other grading systems have been developed for degenerating cervical discs, but their versatility and feasibility in the clinical setting is suboptimal. Methods MRIs of 46 human cervical discs were de-identified and displayed in PowerPoint format. Each slide depicted a single disc with a normal (grade 0) disc displayed in the top right corner for reference. The presentation was given to 25 physicians comprising attending spine surgeons, spine fellows, orthopaedic residents, and two attending musculoskeletal radiologists. The grading system included Grade 0 (normal height compared to C2–3, mid cleft still visible), grade 1 (dark disc, normal height), grade 2 (collapsed disc, few osteophytes), and grade 3 (collapsed disc, many osteophytes). The ease of use of the system was gauged in the participants and the interobserver reliability was calculated. Results The intraclass correlation coefficient for interobserver reliability was 0.87, and 0.94 for intraobserver reliability, indicating excellent reliability. Ninety-five percent and 85 percent of the clinicians judged the grading system to be clinically feasible and useful in daily practice, respectively. Conclusions The grading system is easy to use, has excellent reliability, and can be used for precise and consistent clinician communication. PMID:26949461

  10. Power Supply Reliability Assessment in UPFC-installed Transmission System for ATC Enhancement Considering Transient Stability

    NASA Astrophysics Data System (ADS)

    Masuta, Taisuke; Yokoyama, Akihiko

    With recent development of power electronics technology, power system stability enhancement and optimal power flow control by using Flexible AC Transmission System (FACTS) devices have so far been studied. The FACTS devices to relieve multiple constraints can also make it possible to enhance Available Transfer Capability (ATC) without construction of new transmission lines. The previous research revealed that ATC is expanded by avoiding multiple constraints in OPF using Unified Power Flow Controller (UPFC). For long-term operation of such ATC-expanded power system, it is necessary to evaluate power system reliability. In this paper, the evaluation method of supply reliability for UPFC-installed power system is proposed. Both thermal capacity and transient stability constraints are considered. The effectiveness of the proposed method is shown by numerical examples for IEEJ East10-machine test system.

  11. Reliability, validity and responsiveness of a revised scoring system for the Liverpool Seizure Severity Scale.

    PubMed

    Scott-Lennox, J; Bryant-Comstock, L; Lennox, R; Baker, G A

    2001-04-01

    This report examines the reliability, validity and responsiveness of a revised scoring system for the Liverpool Seizure Severity Scale (LSSS). The revised scoring system was validated using archival data from an observational study and a randomized controlled study. Factor analyses confirmed that a single dimension captured how patients evaluate the severity of their most severe seizures occurring during a recall period. The revised scoring system repositions the severity score to range from 0 (no seizures) to 100 (most severe possible). Scores based on the new system were reliable, had construct validity (known-groups validity), and were responsive to changes in the patients' epilepsy as noted by their physicians. Results suggest that future epilepsy studies assessing seizure severity should incorporate the revised LSSS scoring system and a modified version of the questionnaire that simplifies self-assessment and analyses. The modified version of the LSSS and its scoring system are appended to this report.

  12. The importance of manufacturing processes and their control for the reliability of CPV systems

    NASA Astrophysics Data System (ADS)

    Gombert, Andreas; Rubio, Francisca

    2013-09-01

    Highly concentrating photovoltaic systems (HCPV) based on III-V multi-junction solar cells entered the PV market recently. Since 2008, HCPV power plants operate in various countries and valuable experiences could be gained. Reliability and durability of CPV power plant components are very much impacting the overall life cycle costs of a CPV power plant. Especially the CPV module is a critical component when considering system life time and overall economics. Soitec's CPV Modules based on Concentrix{trade mark, serif} technology are designed for outstanding robustness and reliability even under harsh environmental conditions. The reliability of a CPV module depends significantly on the manufacturing processes and their control. Therefore it is important to design CPV modules for manufacturability.

  13. Interobserver Reliability of the Total Body Score System for Quantifying Human Decomposition.

    PubMed

    Dabbs, Gretchen R; Connor, Melissa; Bytheway, Joan A

    2016-03-01

    Several authors have tested the accuracy of the Total Body Score (TBS) method for quantifying decomposition, but none have examined the reliability of the method as a scoring system by testing interobserver error rates. Sixteen participants used the TBS system to score 59 observation packets including photographs and written descriptions of 13 human cadavers in different stages of decomposition (postmortem interval: 2-186 days). Data analysis used a two-way random model intraclass correlation in SPSS (v. 17.0). The TBS method showed "almost perfect" agreement between observers, with average absolute correlation coefficients of 0.990 and average consistency correlation coefficients of 0.991. While the TBS method may have sources of error, scoring reliability is not one of them. Individual component scores were examined, and the influences of education and experience levels were investigated. Overall, the trunk component scores were the least concordant. Suggestions are made to improve the reliability of the TBS method.

  14. Reliability-economics analysis models for photovoltaic power systems. Volume 2. [SOLREL

    SciTech Connect

    Stember, L.H.; Huss, W.R.; Bridgman, M.S.

    1982-11-01

    This report describes the development of modeling techniques to characterize the reliability, availability, and maintenance costs of photovoltaic power systems. The developed models can be used by designers of PV systems in making design decisions and trade-offs to minimize life-cycle energy costs. Three actual intermediate PV system designs were modeled as examples. The input data estimates used and the results of the analyses are presented.

  15. Bitwise identical compiling setup: prospective for reproducibility and reliability of Earth system modeling

    NASA Astrophysics Data System (ADS)

    Li, R.; Liu, L.; Yang, G.; Zhang, C.; Wang, B.

    2016-02-01

    Reproducibility and reliability are fundamental principles of scientific research. A compiling setup that includes a specific compiler version and compiler flags is an essential technical support for Earth system modeling. With the fast development of computer software and hardware, a compiling setup has to be updated frequently, which challenges the reproducibility and reliability of Earth system modeling. The existing results of a simulation using an original compiling setup may be irreproducible by a newer compiling setup because trivial round-off errors introduced by the change in compiling setup can potentially trigger significant changes in simulation results. Regarding the reliability, a compiler with millions of lines of code may have bugs that are easily overlooked due to the uncertainties or unknowns in Earth system modeling. To address these challenges, this study shows that different compiling setups can achieve exactly the same (bitwise identical) results in Earth system modeling, and a set of bitwise identical compiling setups of a model can be used across different compiler versions and different compiler flags. As a result, the original results can be more easily reproduced; for example, the original results with an older compiler version can be reproduced exactly with a newer compiler version. Moreover, this study shows that new test cases can be generated based on the differences of bitwise identical compiling setups between different models, which can help detect software bugs in the codes of models and compilers and finally improve the reliability of Earth system modeling.

  16. Bitwise identical compiling setup: prospective for reproducibility and reliability of earth system modeling

    NASA Astrophysics Data System (ADS)

    Li, R.; Liu, L.; Yang, G.; Zhang, C.; Wang, B.

    2015-11-01

    Reproducibility and reliability are fundamental principles of scientific research. A compiling setup that includes a specific compiler version and compiler flags is essential technical supports for Earth system modeling. With the fast development of computer software and hardware, compiling setup has to be updated frequently, which challenges the reproducibility and reliability of Earth system modeling. The existing results of a simulation using an original compiling setup may be irreproducible by a newer compiling setup because trivial round-off errors introduced by the change of compiling setup can potentially trigger significant changes in simulation results. Regarding the reliability, a compiler with millions of lines of codes may have bugs that are easily overlooked due to the uncertainties or unknowns in Earth system modeling. To address these challenges, this study shows that different compiling setups can achieve exactly the same (bitwise identical) results in Earth system modeling, and a set of bitwise identical compiling setups of a model can be used across different compiler versions and different compiler flags. As a result, the original results can be more easily reproduced; for example, the original results with an older compiler version can be reproduced exactly with a newer compiler version. Moreover, this study shows that new test cases can be generated based on the differences of bitwise identical compiling setups between different models, which can help detect software bugs or risks in the codes of models and compilers and finally improve the reliability of Earth system modeling.

  17. MSFC Skylab airlock module, volume 2. [systems design and performance, systems support activity, and reliability and safety programs

    NASA Technical Reports Server (NTRS)

    1974-01-01

    System design and performance of the Skylab Airlock Module and Payload Shroud are presented for the communication and caution and warning systems. Crew station and storage, crew trainers, experiments, ground support equipment, and system support activities are also reviewed. Other areas documented include the reliability and safety programs, test philosophy, engineering project management, and mission operations support.

  18. Review of industry efforts to manage pressurized water reactor feedwater nozzle, piping, and feedring cracking and wall thinning

    SciTech Connect

    Shah, V.N.; Ware, A.G.; Porter, A.M.

    1997-03-01

    This report presents a review of nuclear industry efforts to manage thermal fatigue, flow-accelerated corrosion, and water hammer damage to pressurized water reactor (PWR) feedwater nozzles, piping, and feedrings. The review includes an evaluation of design modifications, operating procedure changes, augmented inspection and monitoring programs, and mitigation, repair and replacement activities. Four actions were taken: (a) review of field experience to identify trends of operating events, (b) review of technical literature, (c) visits to PWR plants and a PWR vendor, and (d) solicitation of information from 8 other countries. Assessment of field experience is that licensees have apparently taken sufficient action to minimize feedwater nozzle cracking caused by thermal fatigue and wall thinning of J-tubes and feedwater piping. Specific industry actions to minimize the wall-thinning in feedrings and thermal sleeves were not found, but visual inspection and necessary repairs are being performed. Assessment of field experience indicates that licensees have taken sufficient action to minimize steam generator water hammer in both top-feed and preheat steam generators. Industry efforts to minimize multiple check valve failures that have allowed backflow of steam from a steam generator and have played a major role in several steam generator water hammer events were not evaluated. A major finding of this review is that analysis, inspection, monitoring, mitigation, and replacement techniques have been developed for managing thermal fatigue and flow-accelerated corrosion damage to feedwater nozzles, piping, and feedrings. Adequate training and appropriate applications of these techniques would ensure effective management of this damage.

  19. The implementation and use of Ada on distributed systems with high reliability requirements

    NASA Technical Reports Server (NTRS)

    Knight, J. C.

    1988-01-01

    The use and implementation of Ada were investigated in distributed environments in which reliability is the primary concern. In particular, the focus was on the possibility that a distributed system may be programmed entirely in Ada so that the individual tasks of the system are unconcerned with which processors are being executed, and that failures may occur in the software and underlying hardware. A secondary interest is in the performance of Ada systems and how that performance can be gauged reliably. Primary activities included: analysis of the original approach to recovery in distributed Ada programs using the Advanced Transport Operating System (ATOPS) example; review and assessment of the original approach which was found to be capable of improvement; development of a refined approach to recovery that was applied to the ATOPS example; and design and development of a performance assessment scheme for Ada programs based on a flexible user-driven benchmarking system.

  20. Multiobjective optimization of water distribution systems accounting for economic cost, hydraulic reliability, and greenhouse gas emissions

    NASA Astrophysics Data System (ADS)

    Wu, Wenyan; Maier, Holger R.; Simpson, Angus R.

    2013-03-01

    In this paper, three objectives are considered for the optimization of water distribution systems (WDSs): the traditional objectives of minimizing economic cost and maximizing hydraulic reliability and the recently proposed objective of minimizing greenhouse gas (GHG) emissions. It is particularly important to include the GHG minimization objective for WDSs involving pumping into storages or water transmission systems (WTSs), as these systems are the main contributors of GHG emissions in the water industry. In order to better understand the nature of tradeoffs among these three objectives, the shape of the solution space and the location of the Pareto-optimal front in the solution space are investigated for WTSs and WDSs that include pumping into storages, and the implications of the interaction between the three objectives are explored from a practical design perspective. Through three case studies, it is found that the solution space is a U-shaped curve rather than a surface, as the tradeoffs among the three objectives are dominated by the hydraulic reliability objective. The Pareto-optimal front of real-world systems is often located at the "elbow" section and lower "arm" of the solution space (i.e., the U-shaped curve), indicating that it is more economic to increase the hydraulic reliability of these systems by increasing pipe capacity (i.e., pipe diameter) compared to increasing pumping power. Solutions having the same GHG emission level but different cost-reliability tradeoffs often exist. Therefore, the final decision needs to be made in conjunction with expert knowledge and the specific budget and reliability requirements of the system.

  1. An Evaluation method for C2 Cyber-Physical Systems Reliability Based on Deep Learning

    DTIC Science & Technology

    2014-06-01

    the reliability testing data of the system, we obtain the prior distribution of the relia- bility is 1 1( ) ( ; , )R LG R r  . By Bayes theo- rem ...criticality cyber-physical sys- tems[C]//Proc of ICDCS. Piscataway, NJ: IEEE, 2010:169-178. [17] Zimmer C, Bhat B, Muller F, et al. Time-based intrusion de

  2. Developing a Comprehensive Teaching Evaluation System for Foundation Courses with Enhanced Validity and Reliability

    ERIC Educational Resources Information Center

    Xu, Yueyu

    2012-01-01

    This study aims at developing a comprehensive teaching evaluation system, a more useful educational technology, for achieving relatively reliable and valid results that can be well acknowledged by instructors, students, and by administrators. Adopting multi-method approaches, the study integrates student evaluation, expert evaluation and regular…

  3. Storage Reliability of Missile Materiel Program. Missile Hydraulic and Pneumatic Systems Actuator Analysis

    DTIC Science & Technology

    1976-05-01

    RELIABILITY OF / MISSILE MATERIEL PROGRANI MISSILE gYDRAULIC AND NEUMATIC SYSTEMS ACTUATOR ANALYSIS .. 7 ." Joe C. Mitchell Approved by: Donald R. Earles...Center, Effects of Dormancy on Nonelectronic Components and Materials, Marietta Aerospace 36. Schweickert, T. F., "Extending the Life and Recycle

  4. Automated Energy Distribution and Reliability System: Validation Integration - Results of Future Architecture Implementation

    SciTech Connect

    Buche, D. L.

    2008-06-01

    This report describes Northern Indiana Public Service Co. project efforts to develop an automated energy distribution and reliability system. The purpose of this project was to implement a database-driven GIS solution that would manage all of the company's gas, electric, and landbase objects. This report is second in a series of reports detailing this effort.

  5. 78 FR 29209 - Revisions to Electric Reliability Organization Definition of Bulk Electric System and Rules of...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-17

    ... 17, 2013 Part II Department of Energy Federal Energy Regulatory Commission 18 CFR Part 40 Revisions...; ] DEPARTMENT OF ENERGY Federal Energy Regulatory Commission 18 CFR Part 40 Revisions to Electric Reliability Organization Definition of Bulk Electric System and Rules of Procedure AGENCY: Federal Energy...

  6. 75 FR 57764 - Mandatory Reliability Standards for the Bulk Power System; Supplemental Notice of Technical...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-22

    ... Energy Regulatory Commission Mandatory Reliability Standards for the Bulk Power System; Supplemental Notice of Technical Conference September 14, 2010. On August 19, 2010 the Federal Energy Regulatory Commission announced that a Technical Conference on Frequency Response in the Wholesale Electric Grid...

  7. 75 FR 52528 - Mandatory Reliability Standards for the Bulk-Power System; Notice of Technical Conference

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-26

    ... Energy Regulatory Commission Mandatory Reliability Standards for the Bulk-Power System; Notice of Technical Conference August 19, 2010. Take notice that the Federal Energy Regulatory Commission staff will hold a Technical Conference on Frequency Response in the Wholesale Electric Grid on Thursday,...

  8. 76 FR 64082 - Mandatory Reliability Standards for the Bulk-Power System; Notice of Staff Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-17

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Mandatory Reliability Standards for the Bulk-Power System; Notice of Staff Meeting Take notice that the Federal Energy Regulatory Commission staff will conduct a...

  9. Sensitivity of Space System Availability Predictions to Underlying Component Reliability Estimates

    DTIC Science & Technology

    1989-12-01

    Three Regressors 153 Table C-36. EPS Subsystem Group Screening Coefficient Table for B: ’Three Regressors UNWEI DI , LEAST SQUARES LINEAR RPJBESSION...AD-AO85644). 16. Perrotta, G. and R. Somma . "Reliability of Space Systems: Need for New Tools," Space Ccmnuications and Broadcasting, 1: 189-198 (1983

  10. Reliable data storage system design and implementation for acoustic logging while drilling

    NASA Astrophysics Data System (ADS)

    Hao, Xiaolong; Ju, Xiaodong; Wu, Xiling; Lu, Junqiang; Men, Baiyong; Yao, Yongchao; Liu, Dong

    2016-12-01

    Owing to the limitations of real-time transmission, reliable downhole data storage and fast ground reading have become key technologies in developing tools for acoustic logging while drilling (LWD). In order to improve the reliability of the downhole storage system in conditions of high temperature, intensive shake and periodic power supply, improvements were made in terms of hardware and software. In hardware, we integrated the storage system and data acquisition control module into one circuit board, to reduce the complexity of the storage process, by adopting the controller combination of digital signal processor and field programmable gate array. In software, we developed a systematic management strategy for reliable storage. Multiple-backup independent storage was employed to increase the data redundancy. A traditional error checking and correction (ECC) algorithm was improved and we embedded the calculated ECC code into all management data and waveform data. A real-time storage algorithm for arbitrary length data was designed to actively preserve the storage scene and ensure the independence of the stored data. The recovery procedure of management data was optimized to realize reliable self-recovery. A new bad block management idea of static block replacement and dynamic page mark was proposed to make the period of data acquisition and storage more balanced. In addition, we developed a portable ground data reading module based on a new reliable high speed bus to Ethernet interface to achieve fast reading of the logging data. Experiments have shown that this system can work stably below 155 °C with a periodic power supply. The effective ground data reading rate reaches 1.375 Mbps with 99.7% one-time success rate at room temperature. This work has high practical application significance in improving the reliability and field efficiency of acoustic LWD tools.

  11. Reliability calculation using randomization for Markovian fault-tolerant computing systems

    NASA Technical Reports Server (NTRS)

    Miller, D. R.

    1982-01-01

    The randomization technique for computing transient probabilities of Markov processes is presented. The technique is applied to a Markov process model of a simplified fault tolerant computer system for illustrative purposes. It is applicable to much larger and more complex models. Transient state probabilities are computed, from which reliabilities are derived. An accelerated version of the randomization algorithm is developed which exploits ''stiffness' of the models to gain increased efficiency. A great advantage of the randomization approach is that it easily allows probabilities and reliabilities to be computed to any predetermined accuracy.

  12. Verification of a Monte Carlo Simulation Method to Find Lower Confidence Limits for the Availability and Reliability of Maintained Systems

    DTIC Science & Technology

    1985-12-01

    00 S~DTIC FEB 1 VERIFICATION OF A MONTE CARLO SIMULATION METHOD TO FIND LOWER CONFIDENCE LIMITS FOR THE AVAILABILITY AND RELIABILITY OF MAINTAINED...SIMULATION METHOD TO FIND LOWER CONFIDENCE LIMITS FOR THE AVAILABILITY AND RELIABILITY OF MAINTAINED SYaTEMS THESIS Presented to the Faculty of the...CARLO SIMULATION METHOD TO FIND LOWER CONFIDENCE LIMITS FOR THE AVAILABILITY AND RELIABILITY OF MAINTAINED SYSTEMS I. Introduction The reliability

  13. Sequential Testing of Hypotheses Concerning the Reliability of a System Modeled by a Two-Parameter Weibull Distribution.

    DTIC Science & Technology

    1981-12-01

    preparation of periodic reliability reports. Statistical testing, and in particular Monte Carlo sampling techniques, have proven quite useful when testing and...Reliability. Prepared for: U.S. Army Aviation Systems Command, R&M Division, Product Assurance Directorate (1977). 5. Callahan, J. C. Sequential Probability...Ohio: Air Force Institute of Technology, December 1976. 25 25. Technical Training, Reliability/Maintainability, Reliability. Stu Guide and Workbook

  14. Reliability of on-site greywater treatment systems in Mediterranean and arid environments - a case study.

    PubMed

    Alfiya, Y; Gross, A; Sklarz, M; Friedler, E

    2013-01-01

    On-site greywater (GW) treatment and reuse is gaining popularity. However, a main point of concern is that inadequate treatment of such water may lead to negative environmental and health effects. Maintenance of single-family home GW systems is usually performed by home owners with limited professional support. Therefore, unless GW systems are reliable, environmental and public health might be compromised. This study is aimed at investigating the reliability of on-site recirculated vertical flow constructed wetlands (RVFCW) in 20 single-family homes. In order to ensure reliability, the failure-tree approach was adopted during the design and construction of the systems. The performance of the systems was monitored for 1.5 years, by evaluating treated GW flow and quality, and by recording all malfunctions and maintenance work. Only 39 failures occurred during this period, of which four caused irrigation with impaired quality GW, while the rest led to no irrigation. The mean time between failures (MTBF) was 305 days; two out of the 20 systems suffered from seven malfunctions (each), while nine systems did not fail at all. Thus, it can be postulated that if on-site GW treatment systems are designed with the right controls, and if scheduled (basic and relatively infrequent) maintenance is performed, GW reuse can be safe to the environment and human health.

  15. A PC program to optimize system configuration for desired reliability at minimum cost

    NASA Technical Reports Server (NTRS)

    Hills, Steven W.; Siahpush, Ali S.

    1994-01-01

    High reliability is desired in all engineered systems. One way to improve system reliability is to use redundant components. When redundant components are used, the problem becomes one of allocating them to achieve the best reliability without exceeding other design constraints such as cost, weight, or volume. Systems with few components can be optimized by simply examining every possible combination but the number of combinations for most systems is prohibitive. A computerized iteration of the process is possible but anything short of a super computer requires too much time to be practical. Many researchers have derived mathematical formulations for calculating the optimum configuration directly. However, most of the derivations are based on continuous functions whereas the real system is composed of discrete entities. Therefore, these techniques are approximations of the true optimum solution. This paper describes a computer program that will determine the optimum configuration of a system of multiple redundancy of both standard and optional components. The algorithm is a pair-wise comparative progression technique which can derive the true optimum by calculating only a small fraction of the total number of combinations. A designer can quickly analyze a system with this program on a personal computer.

  16. The Development of a Highly Reliable Power Management and Distribution System for Civil Transport Aircraft

    NASA Technical Reports Server (NTRS)

    Coleman, Anthony S.; Hansen, Irving G.

    1994-01-01

    NASA is pursuing a program in Advanced Subsonic Transport (AST) to develop the technology for a highly reliable Fly-By-Light/Power-By-WIre aircraft. One of the primary objectives of the program is to develop the technology base for confident application of integrated PBW components and systems to transport aircraft to improve operating reliability and efficiency. Technology will be developed so that the present hydraulic and pneumatic systems of the aircraft can be systematically eliminated and replaced by electrical systems. These motor driven actuators would move the aircraft wing surfaces as well as the rudder to provide steering controls for the pilot. Existing aircraft electrical systems are not flight critical and are prone to failure due to Electromagnetic Interference (EMI) (1), ground faults and component failures. In order to successfully implement electromechanical flight control actuation, a Power Management and Distribution (PMAD) System must be designed having a reliability of 1 failure in 10(exp +9) hours, EMI hardening and a fault tolerance architecture to ensure uninterrupted power to all aircraft flight critical systems. The focus of this paper is to analyze, define, and describe technically challenging areas associated with the development of a Power By Wire Aircraft and typical requirements to be established at the box level. The authors will attempt to propose areas of investigation, citing specific military standards and requirements that need to be revised to accommodate the 'More Electric Aircraft Systems'.

  17. Site-specific landslide assessment in Alpine area using a reliable integrated monitoring system

    NASA Astrophysics Data System (ADS)

    Romeo, Saverio; Di Matteo, Lucio; Kieffer, Daniel Scott

    2016-04-01

    Rockfalls are one of major cause of landslide fatalities around the world. The present work discusses the reliability of integrated monitoring of displacements in a rockfall within the Alpine region (Salzburg Land - Austria), taking into account also the effect of the ongoing climate change. Due to the unpredictability of the frequency and magnitude, that threatens human lives and infrastructure, frequently it is necessary to implement an efficient monitoring system. For this reason, during the last decades, integrated monitoring systems of unstable slopes were widely developed and used (e.g., extensometers, cameras, remote sensing, etc.). In this framework, Remote Sensing techniques, such as GBInSAR technique (Groung-Based Interferometric Synthetic Aperture Radar), have emerged as efficient and powerful tools for deformation monitoring. GBInSAR measurements can be useful to achieve an early warning system using surface deformation parameters as ground displacement or inverse velocity (for semi-empirical forecasting methods). In order to check the reliability of GBInSAR and to monitor the evolution of landslide, it is very important to integrate different techniques. Indeed, a multi-instrumental approach is essential to investigate movements both in surface and in depth and the use of different monitoring techniques allows to perform a cross analysis of the data and to minimize errors, to check the data quality and to improve the monitoring system. During 2013, an intense and complete monitoring campaign has been conducted on the Ingelsberg landslide. By analyzing both historical temperature series (HISTALP) recorded during the last century and those from local weather stations, temperature values (Autumn-Winter, Winter and Spring) are clearly increased in Bad Hofgastein area as well as in Alpine region. As consequence, in the last decades the rockfall events have been shifted from spring to summer due to warmer winters. It is interesting to point out that

  18. Markov modeling and reliability analysis of urea synthesis system of a fertilizer plant

    NASA Astrophysics Data System (ADS)

    Aggarwal, Anil Kr.; Kumar, Sanjeev; Singh, Vikram; Garg, Tarun Kr.

    2015-12-01

    This paper deals with the Markov modeling and reliability analysis of urea synthesis system of a fertilizer plant. This system was modeled using Markov birth-death process with the assumption that the failure and repair rates of each subsystem follow exponential distribution. The first-order Chapman-Kolmogorov differential equations are developed with the use of mnemonic rule and these equations are solved with Runga-Kutta fourth-order method. The long-run availability, reliability and mean time between failures are computed for various choices of failure and repair rates of subsystems of the system. The findings of the paper are discussed with the plant personnel to adopt and practice suitable maintenance policies/strategies to enhance the performance of the urea synthesis system of the fertilizer plant.

  19. Reliability considerations of a fuel cell backup power system for telecom applications

    NASA Astrophysics Data System (ADS)

    Serincan, Mustafa Fazil

    2016-03-01

    A commercial fuel cell backup power unit is tested in real life operating conditions at a base station of a Turkish telecom operator. The fuel cell system responds to 256 of 260 electric power outages successfully, providing the required power to the base station. Reliability of the fuel cell backup power unit is found to be 98.5% at the system level. On the other hand, a qualitative reliability analysis at the component level is carried out. Implications of the power management algorithm on reliability is discussed. Moreover, integration of the backup power unit to the base station ecosystem is reviewed in the context of reliability. Impact of inverter design on the stability of the output power is outlined. Significant current harmonics are encountered when a generic inverter is used. However, ripples are attenuated significantly when a custom design inverter is used. Further, fault conditions are considered for real world case studies such as running out of hydrogen, a malfunction in the system, or an unprecedented operating scheme. Some design guidelines are suggested for hybridization of the backup power unit for an uninterrupted operation.

  20. Reliability considerations in long-life outer planet spacecraft system design

    NASA Technical Reports Server (NTRS)

    Casani, E. K.

    1975-01-01

    A Mariner Jupiter/Saturn mission has been planned for 1977. System reliability questions are discussed, taking into account the actual and design lifetime, causes of mission termination, in-flight failures and their consequences for the mission, and the use of redundancy to avoid failures. The design process employed optimizes the use of proven subsystem and system designs and then makes the necessary improvements to increase the lifetime as required.

  1. Test-retest reliability of the Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt in chronic schizophrenics.

    PubMed

    Aucone, E J; Wagner, E E; Raphael, A J; Golden, C J; Espe-Pfeifer, P; Dornheim, L; Seldon, J; Pospisil, T; Proctor-Weber, Z; Calabria, M

    2001-09-01

    This study assesses the test-retest reliability of the revised Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt Test (BGT). The API system identifies 207 possible distortions in a BGT protocol. Test-retest reliability for 40 schizophrenic patients tested twice with a mean interval of 6.4 years (SD=3.8 years) was good, ranging from .71 to .80. Further reliability and validity studies are needed to further demonstrate the effectiveness of the system.

  2. Comparison of intraobserver single-task reliabilities of the Interactive Balance System (IBS) and Vertiguard in asymptomatic subjects.

    PubMed

    Schwesig, René; Hollstein, Lisa; Plontke, Stefan K; Delank, Karl-Stefan; Fieseler, Georg; Rahne, Torsten

    2017-03-01

    The intraobserver reliabilities of the Interactive Balance System (IBS) and Vertiguard were compared in 30 asymptomatic volunteers. Relative reliability for all IBS single tasks and parameters in the IBS was excellent (intraclass correlation coefficient, ICC ≥0.75). The ICC values ranged from 0.78 to 0.89. The ICC values of the Vertiguard system ranged from 0 to 0.75. The cumulative measure of injury risk of the Vertiguard system was highly reliable.

  3. Reliability of Beam Loss Monitor Systems for the Large Hadron Collider

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2005-06-08

    The increase of beam energy and beam intensity, together with the use of super conducting magnets, opens new failure scenarios and brings new criticalities for the whole accelerator protection system. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system, and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particles losses at 7 TeV and assisted by the Fast Beam Current Decay Monitors at 450 GeV. At medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data from the SPS, using temperature and radiation damage experimental data as well as using standard databases. All the data has been processed by reliability software (Isograph). The analysis spaces from the components data to the system configuration.

  4. Reliability of Beam Loss Monitors System for the Large Hadron Collider

    SciTech Connect

    Guaglio, G.; Dehning, B.; Santoni, C.

    2004-11-10

    The employment of superconducting magnets in high energy colliders opens challenging failure scenarios and brings new criticalities for the whole system protection. For the LHC beam loss protection system, the failure rate and the availability requirements have been evaluated using the Safety Integrity Level (SIL) approach. A downtime cost evaluation is used as input for the SIL approach. The most critical systems, which contribute to the final SIL value, are the dump system, the interlock system, the beam loss monitors system and the energy monitor system. The Beam Loss Monitors System (BLMS) is critical for short and intense particle losses, while at medium and higher loss time it is assisted by other systems, such as the quench protection system and the cryogenic system. For BLMS, hardware and software have been evaluated in detail. The reliability input figures have been collected using historical data from the SPS, using temperature and radiation damage experimental data as well as using standard databases. All the data have been processed by reliability software (Isograph). The analysis ranges from the components data to the system configuration.

  5. Discrete Address Beacon System (DABS) Software System Reliability Modeling and Prediction.

    DTIC Science & Technology

    1981-06-01

    19004 DT-A.3.Tef e.0-OW8 , ... t 13. Tyeo Sat ~ n-v d e ed_ 12 Spon soring Agency Name and Address U.S. Department of Transportation Final / / [’’ -4...Model 36 12 Surveillance Module - Reliability Growth Model 39 B-1 DABS Trouble Report/Change Proposal 49 B-2 DABS Trouble Report/Change Proposal Update...Surveillance Module - Reliability Data Summary 38 12 Summary of Software Reliability Predictions 42 13 Summary of Module Critical Error Rates 43 iii I

  6. Reliability and Geographic Trends of 50,000 Photovoltaic Systems in the USA: Preprint

    SciTech Connect

    Jordan, D. C.; Kurtz, S. R.

    2014-09-01

    This paper presents performance and reliability data from nearly 50,000 photovoltaic (PV) systems totaling 1.7 gigawatts installed capacity in the USA from 2009 to 2012 and their geographic trends. About 90% of the normal systems and about 85% of all systems, including systems with known issues, performed to within 10% or better of expected performance. Although considerable uncertainty may exist due to the nature of the data, hotter climates appear to exhibit some degradation not seen in the more moderate climates. Special causes of underperformance and their impacts are delineated by reliability category. Hardware-related issues are dominated by inverter problems (totaling less than 0.5%) and underperforming modules (totaling less than 0.1%). Furthermore, many reliability categories show a significant decrease in occurrence from year 1 to subsequent years, emphasizing the need for higher-quality installations but also the need for improved standards development. The probability of PV system damage because of hail is below 0.05%. Singular weather events can have a significant impact such as a single lightning strike to a transformer or the impact of a hurricane. However, grid outages are more likely to have a significant impact than PV system damage when extreme weather events occur.

  7. A Statistical Testing Approach for Quantifying Software Reliability; Application to an Example System

    SciTech Connect

    Chu, Tsong-Lun; Varuttamaseni, Athi; Baek, Joo-Seok

    2016-11-01

    The U.S. Nuclear Regulatory Commission (NRC) encourages the use of probabilistic risk assessment (PRA) technology in all regulatory matters, to the extent supported by the state-of-the-art in PRA methods and data. Although much has been accomplished in the area of risk-informed regulation, risk assessment for digital systems has not been fully developed. The NRC established a plan for research on digital systems to identify and develop methods, analytical tools, and regulatory guidance for (1) including models of digital systems in the PRAs of nuclear power plants (NPPs), and (2) incorporating digital systems in the NRC's risk-informed licensing and oversight activities. Under NRC's sponsorship, Brookhaven National Laboratory (BNL) explored approaches for addressing the failures of digital instrumentation and control (I and C) systems in the current NPP PRA framework. Specific areas investigated included PRA modeling digital hardware, development of a philosophical basis for defining software failure, and identification of desirable attributes of quantitative software reliability methods. Based on the earlier research, statistical testing is considered a promising method for quantifying software reliability. This paper describes a statistical software testing approach for quantifying software reliability and applies it to the loop-operating control system (LOCS) of an experimental loop of the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL).

  8. GEOTHERMAL / SOLAR HYBRID DESIGNS: USE OF GEOTHERMAL ENERGY FOR CSP FEEDWATER HEATING

    SciTech Connect

    Craig Turchi; Guangdong Zhu; Michael Wagner; Tom Williams; Dan Wendt

    2014-10-01

    This paper examines a hybrid geothermal / solar thermal plant design that uses geothermal energy to provide feedwater heating in a conventional steam-Rankine power cycle deployed by a concentrating solar power (CSP) plant. The geothermal energy represents slightly over 10% of the total thermal input to the hybrid plant. The geothermal energy allows power output from the hybrid plant to increase by about 8% relative to a stand-alone CSP plant with the same solar-thermal input. Geothermal energy is converted to electricity at an efficiency of 1.7 to 2.5 times greater than would occur in a stand-alone, binary-cycle geothermal plant using the same geothermal resource. While the design exhibits a clear advantage during hybrid plant operation, the annual advantage of the hybrid versus two stand-alone power plants depends on the total annual operating hours of the hybrid plant. The annual results in this draft paper are preliminary, and further results are expected prior to submission of a final paper.

  9. Reliability model of fault-tolerant data processing system with primary and backup nodes

    NASA Astrophysics Data System (ADS)

    Rahman, P. A.; Bobkova, E. Yu

    2016-04-01

    This paper deals with the fault-tolerant data processing systems, which are widely used in modern world of information technologies and have acceptable overhead expenses in hardware implementation. A simplified reliability model for duplex systems and the offered by authors advanced model for data processing systems with primary and backup nodes based on a three-state model of recoverable elements, which takes into consideration different failure rates of passive and active nodes and finite time of node activation, are also given. A calculation formula for the availability factor of the dual-node data processing system with primary and backup nodes and calculation examples are also provided.

  10. Reliable finite frequency filter design for networked control systems with sensor faults.

    PubMed

    Ju, He-Hua; Long, Yue; Wang, Heng

    2012-01-01

    This paper is concerned with the reliable finite frequency filter design for networked control systems (NCSs) subject to quantization and data missing. Taking into account quantization, possible data missing and sensor stuck faults, NCSs are modeled in the framework of discrete time-delay switched systems, and the finite frequency l(2) gain is adopted for the filter design of discrete time-delay switched systems, which is converted into a set of linear matrix inequality (LMI) conditions. By the virtues of the derived conditions, a procedure of reliable filter synthesis is presented. Further, the filter gains are characterized in terms of solutions to a convex optimization problem which can be solved by using the semi-definite programme method. Finally, an example is given to illustrate the effectiveness of the proposed method.

  11. Reliable Finite Frequency Filter Design for Networked Control Systems with Sensor Faults

    PubMed Central

    Ju, He-Hua; Long, Yue; Wang, Heng

    2012-01-01

    This paper is concerned with the reliable finite frequency filter design for networked control systems (NCSs) subject to quantization and data missing. Taking into account quantization, possible data missing and sensor stuck faults, NCSs are modeled in the framework of discrete time-delay switched systems, and the finite frequency l2 gain is adopted for the filter design of discrete time-delay switched systems, which is converted into a set of linear matrix inequality (LMI) conditions. By the virtues of the derived conditions, a procedure of reliable filter synthesis is presented. Further, the filter gains are characterized in terms of solutions to a convex optimization problem which can be solved by using the semi-definite programme method. Finally, an example is given to illustrate the effectiveness of the proposed method. PMID:22969382

  12. Robust Reliable Control for Neutral-Type Nonlinear Systems with Time-Varying Delays

    NASA Astrophysics Data System (ADS)

    Mathiyalagan, K.; Sakthivel, R.; Park, Ju. H.

    2014-10-01

    The problem of robust reliable stabilization against actuator failures for a class of uncertain nonlinear neutral systems with time-varying delays is considered. Based on a new Lyapunov-Krasovskii functional, by employing linear matrix inequality technique and free weighting matrix approach, we derived a set of sufficient conditions for the existence of a reliable controller. The derived controller is applied for the robust stabilization of the nonlinear neutral system in the presence of known actuator failure matrix and uncertainties. Further, the results are extended to study the stabilization of neutral systems with unknown actuator failure matrix. The failure of actuators are considered by variables, which are varying in a given interval. The developed theoretical results are established in the form of linear matrix inequalities, which can be easily solved via standard numerical software. Finally, two numerical examples are presented to demonstrate the validity and less conservatism of the obtained results.

  13. Uncertainty quantification and reliability assessment in operational oil spill forecast modeling system.

    PubMed

    Hou, Xianlong; Hodges, Ben R; Feng, Dongyu; Liu, Qixiao

    2017-03-15

    As oil transport increasing in the Texas bays, greater risks of ship collisions will become a challenge, yielding oil spill accidents as a consequence. To minimize the ecological damage and optimize rapid response, emergency managers need to be informed with how fast and where oil will spread as soon as possible after a spill. The state-of-the-art operational oil spill forecast modeling system improves the oil spill response into a new stage. However uncertainty due to predicted data inputs often elicits compromise on the reliability of the forecast result, leading to misdirection in contingency planning. Thus understanding the forecast uncertainty and reliability become significant. In this paper, Monte Carlo simulation is implemented to provide parameters to generate forecast probability maps. The oil spill forecast uncertainty is thus quantified by comparing the forecast probability map and the associated hindcast simulation. A HyosPy-based simple statistic model is developed to assess the reliability of an oil spill forecast in term of belief degree. The technologies developed in this study create a prototype for uncertainty and reliability analysis in numerical oil spill forecast modeling system, providing emergency managers to improve the capability of real time operational oil spill response and impact assessment.

  14. Reliability and validity of the WATSMART three-dimensional optoelectric motion analysis system.

    PubMed

    Scholz, J P

    1989-08-01

    Reliability and validity of the WATSMART (Waterloo Spatial Motion Analysis Recording Technique) system was evaluated under static and dynamic conditions. In experiment 1, infrared light-emitting diodes (IREDs) were placed at the axis and along the arms of a clinical goniometer. Twelve angles in 5-degree increments were each recorded 10 times at each of three spatial locations. Reliability was assessed using intraclass correlation coefficients (ICCs) and analysis-of-variance procedures to determine within-trial variability. The ICCs for all spatial locations exceeded .99. The 95% confidence interval for each angle was less than 0.5 degree in all cases. Criterion-referenced instrument validity was assessed with regression analysis. Slopes of the regression of reconstructed angle on reference angle were close to unity for each spatial location. A systematic error, however, that increased as the goniometer was rotated 45 degrees away from the cameras was evident. In experiment 2, a robotic arm was fitted with four IREDs and made to repeat a defined movement trajectory 10 times at each of three spatial locations. The ICCs for portions of each trajectory ranged from .20 to .99. The results show that reliable and valid results can be obtained from this motion analysis system if adequate precautions are taken to reduce unwanted light reflections. Reliability and validity decreased somewhat as the object was rotated further away from the plane in which the cameras were mounted.

  15. Task analysis for industrial work process from aspects of human reliability and system safety.

    PubMed

    Yu, F J; Hwang, S L; Huang, Y H

    1999-06-01

    In the design, development, and manufacturing stage of industrial products, engineers usually focus on the problems caused by hardware or software, but pay less attention to problems caused by "human error," which may significantly affect system reliability and safety. Although operating procedures are strictly followed, human error still may occur occasionally. Among the influencing factors, the inappropriate design of standard operation procedure (SOP) or standard assembly procedure (SAP) is an important and latent reason for unexpected results found during human operation. To reduce the error probability and error effects of these unexpected behaviors in the industrial work process, overall evaluation of SOP or SAP quality has become an essential task. The human error criticality analysis (HECA) method was developed to identify the potentially critical problems caused by human error in the human operation system. This method performs task analysis on the basis of operation procedure. For example, SOP, analyzes the human error probability (HEP) for each human operation step, and assesses its error effects to the whole system. The results of the analysis will show the interrelationship that exists between critical human tasks, critical human error modes, and human reliability information of the human operation system. To identify the robustness of the model, a case study of initiator assembly tasks was conducted. Results show that the HECA method is practicable in evaluating the operation procedure, and the information is valuable in identifying the means to upgrade human reliability and system safety for human tasks.

  16. Validity and reliability of the Newtest Powertimer 300-series testing system.

    PubMed

    Enoksen, Eystein; Tønnessen, Espen; Shalfawi, Shaher

    2009-01-01

    The aim of the present study was to assess the reliability and validity of the Newtest Powertimer 300-series portable contact mat and photocells (Newtest Oy, Finland). The participants were 20 male soccer players aged 19.1+/-3.5 years. The validity and reliability of the Powertimer (contact mat and photocells) were assessed in a comparison of a laboratory testing method (force platform and photocells) and the Newtest Powertimer system. All participants were tested on 40-m sprint, countermovement jump, and squat jump. The results showed that the Powertimer was a reliable instrument for both jumping and running. The system did not show any marked systematic bias (P<0.05) and the random error associated with it was negligible. A comparison of the laboratory testing method with the Powertimer revealed that the Powertimer contact mat and photocells had poor validity and the bias in measurement differed from that of the laboratory testing method (P<0.05). The Newtest Powertimer testing system was shown to be a useful instrument for measuring jump height and running speed. However, if a comparison of overall values of jumping height is intended, it is important to use the same testing system, because different systems give different results. It is also advisable to use this equipment only if no other "gold standard" equipment is available.

  17. Designing Fault-Injection Experiments for the Reliability of Embedded Systems

    NASA Technical Reports Server (NTRS)

    White, Allan L.

    2012-01-01

    This paper considers the long-standing problem of conducting fault-injections experiments to establish the ultra-reliability of embedded systems. There have been extensive efforts in fault injection, and this paper offers a partial summary of the efforts, but these previous efforts have focused on realism and efficiency. Fault injections have been used to examine diagnostics and to test algorithms, but the literature does not contain any framework that says how to conduct fault-injection experiments to establish ultra-reliability. A solution to this problem integrates field-data, arguments-from-design, and fault-injection into a seamless whole. The solution in this paper is to derive a model reduction theorem for a class of semi-Markov models suitable for describing ultra-reliable embedded systems. The derivation shows that a tight upper bound on the probability of system failure can be obtained using only the means of system-recovery times, thus reducing the experimental effort to estimating a reasonable number of easily-observed parameters. The paper includes an example of a system subject to both permanent and transient faults. There is a discussion of integrating fault-injection with field-data and arguments-from-design.

  18. Reliability of AcuGraph system for measuring skin conductance at acupoints

    PubMed Central

    Mist, Scott D; Aickin, Mikel; Kalnins, Paul; Cleaver, Jim; Batchelor, Roger; Thorne, Tracy; Chamberlin, Steve; Tippens, Kim; Colbert, Agatha P

    2012-01-01

    Objective There are many commercially available instruments for measuring electrical conductance, but there is little information about their reliability. The aim of this study was to quantify measurement variability and assess reliability of the AcuGraph system—a commonly used electrodermal screening device. Methods Four experiments were conducted to measure variability in electrical conductance readings obtained by the AcuGraph system. The fi rst involved measuring known resistors. The second measured non-human organic matter. The third was a test–retest assessment of the Yuan-Source and Jing-Well points in 30 healthy volunteers who were measured by a single operator. The fourth was an interoperator reliability evaluation of seven acupuncturists at the Yuan-Source and Jing-Well acupoints on four individuals at two time points. Results Against known resistors, the AcuGraph had an average coeffi cient of variability (CV) of 1.8% between operators and test–retests. On non-human organic material the AcuGraph had an average CV of 0.9% and 2.8%. When a single operator tested 30 participants, the average reliability for the Yuan-Source points was 0.86 and 0.76 for Jing-Well points with a CV of 23.2% and 25.9% respectively. The average CV for the seven acupuncturists was 24.5% on Yuan-Source points and 23.7% on Jing-Well points. Conclusions The AcuGraph measures known resistors and organic matter accurately and reliably. Skin conductance at acupoints recorded by one operator was also reliable. There was less consistency in electrodermal recordings obtained by seven different operators. Operator training and technical improvements to the AcuGraph may improve consistency among operators. PMID:21602233

  19. Failure Modes Effects and Criticality Analysis, an Underutilized Safety, Reliability, Project Management and Systems Engineering Tool

    NASA Astrophysics Data System (ADS)

    Mullin, Daniel Richard

    2013-09-01

    The majority of space programs whether manned or unmanned for science or exploration require that a Failure Modes Effects and Criticality Analysis (FMECA) be performed as part of their safety and reliability activities. This comes as no surprise given that FMECAs have been an integral part of the reliability engineer's toolkit since the 1950s. The reasons for performing a FMECA are well known including fleshing out system single point failures, system hazards and critical components and functions. However, in the author's ten years' experience as a space systems safety and reliability engineer, findings demonstrate that the FMECA is often performed as an afterthought, simply to meet contract deliverable requirements and is often started long after the system requirements allocation and preliminary design have been completed. There are also important qualitative and quantitative components often missing which can provide useful data to all of project stakeholders. These include; probability of occurrence, probability of detection, time to effect and time to detect and, finally, the Risk Priority Number. This is unfortunate as the FMECA is a powerful system design tool that when used effectively, can help optimize system function while minimizing the risk of failure. When performed as early as possible in conjunction with writing the top level system requirements, the FMECA can provide instant feedback on the viability of the requirements while providing a valuable sanity check early in the design process. It can indicate which areas of the system will require redundancy and which areas are inherently the most risky from the onset. Based on historical and practical examples, it is this author's contention that FMECAs are an immense source of important information for all involved stakeholders in a given project and can provide several benefits including, efficient project management with respect to cost and schedule, system engineering and requirements management

  20. Assessing validity and reliability of resting metabolic rate in six gas analysis systems.

    PubMed

    Cooper, Jamie A; Watras, Abigail C; O'Brien, Matthew J; Luke, Amy; Dobratz, Jennifer R; Earthman, Carrie P; Schoeller, Dale A

    2009-01-01

    The Deltatrac Metabolic Monitor (DTC) (VIASYS Healthcare Inc, SensorMedics, Yorba Linda, CA), one of the most popular indirect calorimetry systems for measuring resting metabolic rate (RMR) in human subjects, is no longer being manufactured. This study compared five different gas analysis systems to the DTC. RMR was measured by the DTC and at least one other instrument at three study sites for a total of 38 participants. The five indirect calorimetry systems included the MedGraphics CPX Ultima (Medical Graphics Corp, St Paul, MN), the MedGem (Microlife USA, Golden, CO), Vmax Encore 29 System (VIASYS Healthcare Inc, Yorba Linda, CA), the TrueOne 2400 (Parvo Medics, Sandy, UT), and the Korr ReeVue (Korr Medical Technologies, Salt Lake City, UT). Validity was assessed using paired t tests to compare means; reliability was assessed by using both paired t tests and root mean square calculations with F tests for significance. Within-subject comparisons for validity of RMR revealed a significant difference between the DTC and the Ultima system. Bland-Altman plot analysis showed significant bias with increasing RMR values for the Korr and MedGem systems. Respiratory exchange ratio (RER) analysis showed a significant difference between the DTC and the Ultima system and a trend for a difference with the Vmax system (P=0.09). Reliability assessment for RMR revealed that all instruments had a significantly larger coefficient of variation (CV) (ranging from 4.8% to 10.9%) for RMR compared to the 3.0% CV for the DTC. Reliability assessment for RER data showed none of the instrument CVs was significantly larger than the DTC CV. The results were quite disappointing because none of the instruments equaled the within-person reliability of the DTC. The TrueOne and Vmax systems were the most valid instruments in comparison with the DTC for both RMR and RER assessment. Further testing is needed to identify an instrument with the reliability and validity of the DTC.

  1. Consortium for Electric Reliability Technology Solutions Grid of the Future White Paper on Review of Recent Reliability Issues and Systems Events

    SciTech Connect

    Hauer, John F.; Dagle, Jeffery E.

    1999-12-01

    This report is one of six reports developed under the U.S. Department of Energy (DOE) program in Power System Integration and Reliability (PSIR). The objective of this report is to review, analyze, and evaluate critical reliability issues demonstrated by recent disturbance events in the North America power system. Eleven major disturbances are examined, most occurring in this decade. The strategic challenge is that the pattern of technical need has persisted for a long period of time. For more than a decade, anticipation of market deregulation has been a major disincentive to new investments in system capacity. It has also inspired reduced maintenance of existing assets. A massive infusion of better technology is emerging as the final option to continue reliable electrical services. If an investment in better technology will not be made in a timely manner, then North America should plan its adjustments to a very different level of electrical service. It is apparent that technical operations staff among the utilities can be very effective at marshaling their forces in the immediate aftermath of a system emergency, and that serious disturbances often lead to improved mechanisms for coordinated operation. It is not at all apparent that such efforts can be sustained through voluntary reliability organizations in which utility personnel external to those organizations do most of the technical work. The eastern interconnection shows several situations in which much of the technical support has migrated from the utilities to the Independent System Operator (ISO), and the ISO staffs or shares staff with the regional reliability council. This process may be a natural and very positive consequence of utility restructuring. If so, the process should be expedited in regions where it is less advanced.

  2. Resource allocatiion: sequential data collection for reliability analysis involving systems and component level data

    SciTech Connect

    Anderson-cooke, Christine M

    2010-01-01

    In analyzing the reliability of complex systems, several types of data from full-system tests to component level tests are commonly available and are used. After a preliminary analysis, additional resources may be available to collect new data. The goal of resource allocation is to identify the best new data to collect to maximally improve the prediction of system reliability. While several possible definitions of 'maximally improve' are possible, we focus on reducing the uncertainty or the width of the uncertainty interval for the prediction of system reliability at a user-specified age(s). In this paper, we present an algorithm that allows us to estimate the anticipated improvement to the analysis with the addition of new data, based on current understanding of all of the statistical model parameters. This quantitative assessment of the anticipated improvement can be helpful to justify the benefits of collecting new data. Additionally by comparing different potential allocations, it is possible to determine what new data should be collected to improve our understanding of the response. This optimization takes into account the relative cost of different data types and can be based on flexible allocation options, or subject to logistical constraints.

  3. Reliability model generator

    NASA Technical Reports Server (NTRS)

    McMann, Catherine M. (Inventor); Cohen, Gerald C. (Inventor)

    1991-01-01

    An improved method and system for automatically generating reliability models for use with a reliability evaluation tool is described. The reliability model generator of the present invention includes means for storing a plurality of low level reliability models which represent the reliability characteristics for low level system components. In addition, the present invention includes means for defining the interconnection of the low level reliability models via a system architecture description. In accordance with the principles of the present invention, a reliability model for the entire system is automatically generated by aggregating the low level reliability models based on the system architecture description.

  4. Reliability of Physical Systems: Detection of Malicious Subcircuits (Trojan Circuits) in Sequential Circuits

    NASA Astrophysics Data System (ADS)

    Matrosova, A. Yu.; Kirienko, I. E.; Tomkov, V. V.; Miryutov, A. A.

    2016-12-01

    Reliability of physical systems is provided by reliability of their parts including logical ones. Insertion of malicious subcircuits that can destroy logical circuit or cause leakage of confidential information from a system necessitates the detection of such subcircuits followed by their masking if possible. We suggest a method of finding a set of sequential circuit nodes in which Trojan Circuits can be inserted. The method is based on random estimations of controllability and observability of combinational nodes calculated using a description of sequential circuit working area and an evidence of existence of a transfer sequence for the proper set of internal states without finding the sequence itself. The method allows cutting calculations using operations on Reduced Ordered Binary Decision Diagrams (ROBDDs) that can depend only on the state variables of the circuit. The approach, unlike traditional ones, does not require preliminary sequential circuit simulation but can use its results. It can be used when malicious circuits cannot be detected during sequential circuit verification.

  5. Reliability training

    NASA Technical Reports Server (NTRS)

    Lalli, Vincent R. (Editor); Malec, Henry A. (Editor); Dillard, Richard B.; Wong, Kam L.; Barber, Frank J.; Barina, Frank J.

    1992-01-01

    Discussed here is failure physics, the study of how products, hardware, software, and systems fail and what can be done about it. The intent is to impart useful information, to extend the limits of production capability, and to assist in achieving low cost reliable products. A review of reliability for the years 1940 to 2000 is given. Next, a review of mathematics is given as well as a description of what elements contribute to product failures. Basic reliability theory and the disciplines that allow us to control and eliminate failures are elucidated.

  6. Rugged, reliable, and secured data storage solutions for airborne ISR systems

    NASA Astrophysics Data System (ADS)

    Tsur, Ofer

    2004-08-01

    Rugged, reliable and secure data storage is of major concern to engineers designing Airborne Intelligence, Surveillance, Reconnaissance (ISR) systems. Operation under harsh conditions of shock, vibration and high altitude in extreme temperature ranges is an essential requirement. Due to its rotating mechanism, a mechanical disk cannot provide top-level data reliability in such an environment. Other Commercial Off The Shelf (COTS) solutions can replace mechanical disks. This paper describes some of these alternatives and highlights their cost-effectiveness. One alternative is a ruggedized mechanical disk, a mechanical disk sealed in a rigid cartridge. Another alternative is the solid-state flash disk that, like the mechanical disk, retains data when power is off, and is a "drop-in replacement" for the mechanical disk for reliability in harsh environments. Flash disk manufacturers incorporate special methods to enhance endurance and reliability for military designers. This paper also describes the mandatory requirements of the DoD, NSA and the US Air Force for erasing confidential data in storage devices. This issue is vital, especially since the P-3 landed forcibly on China"s soil. Some flash disk vendors meet security requirements with Fast Secure Erase and Sanitize, enabling data declassification in seconds, even without power.

  7. Assessing system reliability and allocating resources: a bayesian approach that integrates multi-level data

    SciTech Connect

    Graves, Todd L; Hamada, Michael S

    2008-01-01

    Good estimates of the reliability of a system make use of test data and expert knowledge at all available levels. Furthermore, by integrating all these information sources, one can determine how best to allocate scarce testing resources to reduce uncertainty. Both of these goals are facilitated by modern Bayesian computational methods. We apply these tools to examples that were previously solvable only through the use of ingenious approximations, and use genetic algorithms to guide resource allocation.

  8. A simulation model for reliability evaluation of Space Station power systems

    NASA Technical Reports Server (NTRS)

    Singh, C.; Patton, A. D.; Kumar, Mudit; Wagner, H.

    1988-01-01

    A detailed simulation model for the hybrid Space Station power system is presented which allows photovoltaic and solar dynamic power sources to be mixed in varying proportions. The model considers the dependence of reliability and storage characteristics during the sun and eclipse periods, and makes it possible to model the charging and discharging of the energy storage modules in a relatively accurate manner on a continuous basis.

  9. Test and Evaluation of System Reliability Availability and Maintainability, A Primer

    DTIC Science & Technology

    1982-03-01

    measure, but is a useful mathematical term which frequently appears in many engineering and statistical calculations. As we will see in later chapters...no unscheduled aupply demand will occ•ur following the comple- tion of a specific mission profile. The mathematical models used to evaluate mission...requirements: * RS 0.90RF (0.955(60.997 0.957 Commentary This represents a very simple form of reliability apportionment; that is, allocating a system- level

  10. Missile and Space Systems Reliability versus Cost Trade-Off Study

    DTIC Science & Technology

    1983-01-01

    account for nonlinearities and the readiness requirement scored as (1) for present or (0) for not present. 53 0’ 11- TABLE 3-12 -PROGRAM/SYSTEM...implementing an acceptable reliability progam . While only 10% felt that improper tailoring was at fault, an equally divided response of 37Z each felt the...account for a strong nonlinear influence due to program phase. A more rigorous investigation would use a phase-by-phase analysis of the data, but the

  11. The role of reliability graph models in assuring dependable operation of complex hardware/software systems

    NASA Technical Reports Server (NTRS)

    Patterson-Hine, F. A.; Davis, Gloria J.; Pedar, A.

    1991-01-01

    The complexity of computer systems currently being designed for critical applications in the scientific, commercial, and military arenas requires the development of new techniques for utilizing models of system behavior in order to assure 'ultra-dependability'. The complexity of these systems, such as Space Station Freedom and the Air Traffic Control System, stems from their highly integrated designs containing both hardware and software as critical components. Reliability graph models, such as fault trees and digraphs, are used frequently to model hardware systems. Their applicability for software systems has also been demonstrated for software safety analysis and the analysis of software fault tolerance. This paper discusses further uses of graph models in the design and implementation of fault management systems for safety critical applications.

  12. A Dirichlet reputation system in reliable routing of wireless ad hoc network

    SciTech Connect

    Yang, Dr. Li; Cui, Xiaohui; Cemerlic, Alma

    2010-01-01

    Ad hoc networks are very helpful in situations when no fixed network infrastructure is available, such as natural disasters and military conflicts. In such a network, all wireless nodes are equal peers simultaneously serving as both senders and routers for other nodes. Therefore, how to route packets through reliable paths becomes a fundamental problems when behaviors of certain nodes deviate from wireless ad hoc routing protocols. We proposed a novel Dirichlet reputation model based on Bayesian inference theory which evaluates reliability of each node in terms of packet delivery. Our system offers a way to predict and select a reliable path through combination of first-hand observation and second-hand reputation reports. We also proposed moving window mechanism which helps to adjust ours responsiveness of our system to changes of node behaviors. We integrated the Dirichlet reputation into routing protocol of wireless ad hoc networks. Our extensive simulation indicates that our proposed reputation system can improve good throughput of the network and reduce negative impacts caused by misbehaving nodes.

  13. Robust reliable sampled-data control for switched systems with application to flight control

    NASA Astrophysics Data System (ADS)

    Sakthivel, R.; Joby, Maya; Shi, P.; Mathiyalagan, K.

    2016-11-01

    This paper addresses the robust reliable stabilisation problem for a class of uncertain switched systems with random delays and norm bounded uncertainties. The main aim of this paper is to obtain the reliable robust sampled-data control design which involves random time delay with an appropriate gain control matrix for achieving the robust exponential stabilisation for uncertain switched system against actuator failures. In particular, the involved delays are assumed to be randomly time-varying which obeys certain mutually uncorrelated Bernoulli distributed white noise sequences. By constructing an appropriate Lyapunov-Krasovskii functional (LKF) and employing an average-dwell time approach, a new set of criteria is derived for ensuring the robust exponential stability of the closed-loop switched system. More precisely, the Schur complement and Jensen's integral inequality are used in derivation of stabilisation criteria. By considering the relationship among the random time-varying delay and its lower and upper bounds, a new set of sufficient condition is established for the existence of reliable robust sampled-data control in terms of solution to linear matrix inequalities (LMIs). Finally, an illustrative example based on the F-18 aircraft model is provided to show the effectiveness of the proposed design procedures.

  14. Reliability analysis of solar photovoltaic system using hourly mean solar radiation data

    SciTech Connect

    Moharil, Ravindra M.; Kulkarni, Prakash S.

    2010-04-15

    This paper presents the hourly mean solar radiation and standard deviation as inputs to simulate the solar radiation over a year. Monte Carlo simulation (MCS) technique is applied and MATLAB program is developed for reliability analysis of small isolated power system using solar photovoltaic (SPV). This paper is distributed in two parts. Firstly various solar radiation prediction methods along with hourly mean solar radiation (HMSR) method are compared. The comparison is carried on the basis of predicted electrical power generation with actual power generated by SPV system. Estimation of solar photovoltaic power using HMSR method is close to the actual power generated by SPV system. The deviation in monsoon months is due to the cloud cover. In later part of the paper various reliability indices are obtained by HMSR method using MCS technique. Load model used is IEEE-RTS. Reliability indices, additional load hours (ALH) and additional power (AP) reduces exponentially with increase in load indicates that a SPV source will offset maximum fuel when all of its generated energy is utilized. Fuel saving calculation is also investigated. Case studies are presented for Sagardeep Island in West Bengal state of India. (author)

  15. Assessment of system reliability for a stochastic-flow distribution network with the spoilage property

    NASA Astrophysics Data System (ADS)

    Lin, Yi-Kuei; Huang, Cheng-Fu; Yeh, Cheng-Ta

    2016-04-01

    In supply chain management, satisfying customer demand is the most concerned for the manager. However, the goods may rot or be spoilt during delivery owing to natural disasters, inclement weather, traffic accidents, collisions, and so on, such that the intact goods may not meet market demand. This paper concentrates on a stochastic-flow distribution network (SFDN), in which a node denotes a supplier, a transfer station, or a market, while a route denotes a carrier providing the delivery service for a pair of nodes. The available capacity of the carrier is stochastic because the capacity may be partially reserved by other customers. The addressed problem is to evaluate the system reliability, the probability that the SFDN can satisfy the market demand with the spoilage rate under the budget constraint from multiple suppliers to the customer. An algorithm is developed in terms of minimal paths to evaluate the system reliability along with a numerical example to illustrate the solution procedure. A practical case of fruit distribution is presented accordingly to emphasise the management implication of the system reliability.

  16. Reliability study: raw and make-up water system, Portsmouth Gaseous Diffusion Plant

    SciTech Connect

    Peterman, S.M.; Wiehle, W.E.; Walder, A.; Houk, T.C.; West, R.M.

    1981-09-01

    A reliability study for determining the ability of the raw and make-up water system to provide reliable and adequate service through the year 2000 has been completed. This study includes an evaluation of the well fields, X-608 Raw Water Pump House, X-605 Booster Station Complex, X-611 Water Treatment Complex, and the associated piping. The raw and make-up water system is in good overall condition, but to maintain this condition, the reliability study team made the following recommendations: (1) increase well field capacity; (2) replace certain speed reducers at X-611; (3) repair deteriorated poles, crossarms, and accessories on F-2 and W-1 feeders; (4) stabilize the landslide in vicinity of the 48 in. raw water main; and (5) initiate further investigation, testing, or engineering studies to correct deficiencies in the supervisory control system between well fields, pump house, and X-611, determine if the 2400 volt underground cables to X-608A wells should be replaced.

  17. Interrater Reliability of the Original and a Revised Scoring System for the Developmental Test of Visual-Motor Integration.

    ERIC Educational Resources Information Center

    Lepkin, Sheila Ratsch; Pryzwansky, Walter B.

    1983-01-01

    Investigated the interrater reliability of teachers' and school psychology externs' scoring of protocols for the Developmental Test of Visual-Motor Integration (VMI), using a revised scoring system. Results showed high reliability coefficients for all raters, regardless of the scoring system employed. The influence of rater training is discussed.…

  18. System design and reliability considerations for an intermediate-size photovoltaic power system for a remote application

    NASA Astrophysics Data System (ADS)

    Noel, G. T.; Stember, L. H.; Carmichael, D. C.

    The design of a photovoltaic power system for remote applications is described. The preliminary requirements placed on the system are high reliability of power and low life-cycle cost, considering equipment, remote installation, and operation and maintenance costs. The design incorporates flat-panel modules assembled onto steel frames and prewired prior to shipment to the site, in order to minimize on-site installation costs, skilled labor requirements, and risk of costly delays and failures. Other components include power conditioning units, battery storage, battery charger, back-up diesel generators, and controls. A methodology for system reliability analysis using the fault-tree technique is illustrated to aid in system design, and an assessment is made of mean time between failures (MTBF), mean time to restore/repair (MTTR), and system availability.

  19. A highly reliable, autonomous data communication subsystem for an advanced information processing system

    NASA Technical Reports Server (NTRS)

    Nagle, Gail; Masotto, Thomas; Alger, Linda

    1990-01-01

    The need to meet the stringent performance and reliability requirements of advanced avionics systems has frequently led to implementations which are tailored to a specific application and are therefore difficult to modify or extend. Furthermore, many integrated flight critical systems are input/output intensive. By using a design methodology which customizes the input/output mechanism for each new application, the cost of implementing new systems becomes prohibitively expensive. One solution to this dilemma is to design computer systems and input/output subsystems which are general purpose, but which can be easily configured to support the needs of a specific application. The Advanced Information Processing System (AIPS), currently under development has these characteristics. The design and implementation of the prototype I/O communication system for AIPS is described. AIPS addresses reliability issues related to data communications by the use of reconfigurable I/O networks. When a fault or damage event occurs, communication is restored to functioning parts of the network and the failed or damage components are isolated. Performance issues are addressed by using a parallelized computer architecture which decouples Input/Output (I/O) redundancy management and I/O processing from the computational stream of an application. The autonomous nature of the system derives from the highly automated and independent manner in which I/O transactions are conducted for the application as well as from the fact that the hardware redundancy management is entirely transparent to the application.

  20. Model-Driven Development of Reliable Avionics Architectures for Lunar Surface Systems

    NASA Technical Reports Server (NTRS)

    Borer, Nicholas; Claypool, Ian; Clark, David; West, John; Somervill, Kevin; Odegard, Ryan; Suzuki, Nantel

    2010-01-01

    This paper discusses a method used for the systematic improvement of NASA s Lunar Surface Systems avionics architectures in the area of reliability and fault-tolerance. This approach utilizes an integrated system model to determine the effects of component failure on the system s ability to provide critical functions. A Markov model of the potential degraded system modes is created to characterize the probability of these degraded modes, and the system model is run for each Markov state to determine its status (operational or system loss). The probabilistic results from the Markov model are first produced from state transition rates based on NASA data for heritage failure rate data of similar components. An additional set of probabilistic results are created from a representative set of failure rates developed for this study, for a variety of component quality grades (space-rated, mil-spec, ruggedized, and commercial). The results show that careful application of redundancy and selected component improvement should result in Lunar Surface Systems architectures that exhibit an appropriate degree of fault-tolerance, reliability, performance, and affordability.

  1. Reliability assessment of non-utility generation and demand-side management in composite power systems

    NASA Astrophysics Data System (ADS)

    Adzanu, Steve Kwaku

    The last two decades have brought about significant changes in the resource planning environment of electric power utilities throughout the world. The conventional generation technologies that have been the backbone of every electric utility i.e., coal, hydro, nuclear, oil and natural gas, are being re-examined to address environmental concerns and resource utilization. The research described in this thesis focuses on the adequacy and economic assessment of non-utility generation (NUG) and demand-side management (DSM) initiatives within a typical power system. The main objective was to examine and extend the ability of the contingency enumeration approach to evaluate the economic reliability benefits of incorporating NUG and DSM options separately or jointly in composite system adequacy assessment. Two test systems were employed in the evaluations. The studies undertaken in this thesis demonstrate the need for accurate load model representations which clearly reflect the mix of customer sectors at each bus. Chronological hourly load curves were developed for each load bus in the test systems recognizing the individual load profiles of the customers. The adequacy and economic implications of demand-side management initiatives in the test systems were examined at each load point in the composite generation and transmission configuration. This thesis illustrates the development of techniques by which system planners and operators can incorporate reliability cost/worth assessment power system applications. Focus is placed in the thesis on the utilization of reliability cost/worth concepts in integrated resource planning in the form of NUG additions and DSM initiatives. Methods for the joint implementation of NUG and DSM options in a composite power system are presented and examples from the studies conducted are used to illustrate the procedures. Studies are presented which illustrate the impacts of NUG additions and DSM initiatives on the test system planning reserve

  2. Comparison of RETRAN and RELAP5 models to Oyster Creek loss of feedwater transient

    SciTech Connect

    Alammar, M.A.

    1985-07-01

    The Oyster Creek Generating Station is a 1930MW(thermal) boiling water reactor 2 plant. During the past year, a program to qualify the Oyster Creek RETRAN model against plant data was in effect at GPU Nuclear. As part of this program, a major transient that occurred on May 2, 1979, was chosen for analysis comparison. While operating at 100% power, a spurious high-pressure scram occurred, coupled with a simultaneous trip of the recirculation pumps. Other events resulted in a loss of feedwater flow and the inadvertent closure, by the operator, of the recirculation pump discharge valves, which limited recirculation flow to only five 0.0508-m (2-in.) bypass lines. The operator proceeded to isolate the vessel and use the emergency condensers for decay heat removal until feed flow was restored 45 min later. The plant RETRAN model was benchmarked against this transient for the first 45 min, using 39 volumes, 54 junctions, 25 heat conductors, and a bubble rise model for the separator/upper downcomer regions. The RETRAN results showed good agreement with plant data for downcomer level and dome pressure. The unique coupling between the downcomer and core zone liquid levels during the cyclic operation of the emergency condensers was simulated quite well. The use of the bubble rise model for the separator/ upper downcomer, however, resulted in a higher dome pressure given by RETRAN, which is believed to be due to the 100% separation efficiency of the model as compared to the degraded separator efficiencies at offoptimum operating conditions. The fuel zone liquid level was an outstanding issue at the time where a conservative simple calculation showed that the core remained covered during the transient. The RETRAN model confirmed that, but also showed that the fuel zone liquid mass during the transient was more than that at steady state.

  3. Reliability enhancement of APR + diverse protection system regarding common cause failures

    SciTech Connect

    Oh, Y. G.; Kim, Y. M.; Yim, H. S.; Lee, S. J.

    2012-07-01

    The Advanced Power Reactor Plus (APR +) nuclear power plant design has been developed on the basis of the APR1400 (Advanced Power Reactor 1400 MWe) to further enhance safety and economics. For the mitigation of Anticipated Transients Without Scram (ATWS) as well as Common Cause Failures (CCF) within the Plant Protection System (PPS) and the Emergency Safety Feature - Component Control System (ESF-CCS), several design improvement features have been implemented for the Diverse Protection System (DPS) of the APR + plant. As compared to the APR1400 DPS design, the APR + DPS has been designed to provide the Safety Injection Actuation Signal (SIAS) considering a large break LOCA accident concurrent with the CCF. Additionally several design improvement features, such as channel structure with redundant processing modules, and changes of system communication methods and auto-system test methods, are introduced to enhance the functional reliability of the DPS. Therefore, it is expected that the APR + DPS can provide an enhanced safety and reliability regarding possible CCF in the safety-grade I and C systems as well as the DPS itself. (authors)

  4. A pulse-width modulated, high reliability charge controller for small photovoltaic systems

    SciTech Connect

    Gerken, K.; Welsh, D.

    1997-02-01

    This report presents the results of a development effort to design, test and begin production of a new class of small photovoltaic (PV) charge controllers. Sandia National Laboratories provided technical support, test data and financial support through a Balance-of-System Development contract. One of the objectives of the development was to increase user confidence in small PV systems by improving the reliability and operating life of the system controllers. Another equally important objective was to improve the economics of small PV systems by extending the battery lifetimes. Using new technology and advanced manufacturing techniques, these objectives were accomplished. Because small stand-alone PV systems account for over one third of all PV modules shipped, the positive impact of improving the reliability and economics of PV systems in this market segment will be felt throughout the industry. The results of verification testing of the new product are also included in this report. The initial design goals and specifications were very aggressive, but the extensive testing demonstrates that all the goals were achieved. Production of the product started in May at a rate of 2,000 units per month. Over 40 Morningstar distributors (5 US and 35 overseas) have taken delivery in the first 2 months of shipments. Initial customer reactions to the new controller have been very favorable.

  5. Real-Time Reliability Verification for UAV Flight Control System Supporting Airworthiness Certification.

    PubMed

    Xu, Haiyang; Wang, Ping

    2016-01-01

    In order to verify the real-time reliability of unmanned aerial vehicle (UAV) flight control system and comply with the airworthiness certification standard, we proposed a model-based integration framework for modeling and verification of time property. Combining with the advantages of MARTE, this framework uses class diagram to create the static model of software system, and utilizes state chart to create the dynamic model. In term of the defined transformation rules, the MARTE model could be transformed to formal integrated model, and the different part of the model could also be verified by using existing formal tools. For the real-time specifications of software system, we also proposed a generating algorithm for temporal logic formula, which could automatically extract real-time property from time-sensitive live sequence chart (TLSC). Finally, we modeled the simplified flight control system of UAV to check its real-time property. The results showed that the framework could be used to create the system model, as well as precisely analyze and verify the real-time reliability of UAV flight control system.

  6. Real-Time Reliability Verification for UAV Flight Control System Supporting Airworthiness Certification

    PubMed Central

    Xu, Haiyang; Wang, Ping

    2016-01-01

    In order to verify the real-time reliability of unmanned aerial vehicle (UAV) flight control system and comply with the airworthiness certification standard, we proposed a model-based integration framework for modeling and verification of time property. Combining with the advantages of MARTE, this framework uses class diagram to create the static model of software system, and utilizes state chart to create the dynamic model. In term of the defined transformation rules, the MARTE model could be transformed to formal integrated model, and the different part of the model could also be verified by using existing formal tools. For the real-time specifications of software system, we also proposed a generating algorithm for temporal logic formula, which could automatically extract real-time property from time-sensitive live sequence chart (TLSC). Finally, we modeled the simplified flight control system of UAV to check its real-time property. The results showed that the framework could be used to create the system model, as well as precisely analyze and verify the real-time reliability of UAV flight control system. PMID:27918594

  7. Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) Quality Assurance Manual

    SciTech Connect

    C. L. Smith; R. Nims; K. J. Kvarfordt; C. Wharton

    2008-08-01

    The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) is a software application developed for performing a complete probabilistic risk assessment using a personal computer running the Microsoft Windows operating system. SAPHIRE is primarily funded by the U.S. Nuclear Regulatory Commission (NRC). The role of the INL in this project is that of software developer and tester. This development takes place using formal software development procedures and is subject to quality assurance (QA) processes. The purpose of this document is to describe how the SAPHIRE software QA is performed for Version 6 and 7, what constitutes its parts, and limitations of those processes.

  8. The implementation and use of Ada on distributed systems with high reliability requirements

    NASA Technical Reports Server (NTRS)

    Knight, J. C.

    1984-01-01

    The use and implementation of Ada in distributed environments in which reliability is the primary concern is investigated. Emphasis is placed on the possibility that a distributed system may be programmed entirely in ADA so that the individual tasks of the system are unconcerned with which processors they are executing on, and that failures may occur in the software or underlying hardware. The primary activities are: (1) Continued development and testing of our fault-tolerant Ada testbed; (2) consideration of desirable language changes to allow Ada to provide useful semantics for failure; (3) analysis of the inadequacies of existing software fault tolerance strategies.

  9. The implementation and use of Ada on distributed systems with high reliability requirements

    NASA Technical Reports Server (NTRS)

    Knight, J. C.

    1986-01-01

    The use and implementation of Ada in distributed environments in which reliability is the primary concern were investigted. A distributed system, programmed entirely in Ada, was studied to assess the use of individual tasks without concern for the processor used. Continued development and testing of the fault tolerant Ada testbed; development of suggested changes to Ada to cope with the failures of interest; design of approaches to fault tolerant software in real time systems, and the integration of these ideas into Ada; and the preparation of various papers and presentations were discussed.

  10. PV System 'Availability' as a Reliability Metric -- Improving Standards, Contract Language and Performance Models

    SciTech Connect

    Klise, Geoffrey T.; Hill, Roger; Walker, Andy; Dobos, Aron; Freeman, Janine

    2016-11-21

    The use of the term 'availability' to describe a photovoltaic (PV) system and power plant has been fraught with confusion for many years. A term that is meant to describe equipment operational status is often omitted, misapplied or inaccurately combined with PV performance metrics due to attempts to measure performance and reliability through the lens of traditional power plant language. This paper discusses three areas where current research in standards, contract language and performance modeling is improving the way availability is used with regards to photovoltaic systems and power plants.

  11. A random onset model for degradation of high-reliability systems

    SciTech Connect

    Vanderwiel, Scott A; Wilson, Alyson G; Graves, Todd L; Reese, Christopher S

    2009-07-22

    Both the U. S. Department of Defense (DoD) and Department of Energy (DOE) maintain weapons stockpiles: items like bullets, missiles and bombs that have already been produced and are being stored until needed. Ideally, these stockpiles maintain high reliability over time. To assess reliability, a surveillance program is implemented, where units are periodically removed from the stockpile and tested. The most definitive tests typically destroy the weapons so a given unit is tested only once. Surveillance managers need to decide how many units should be tested, how often they should be tested, what tests should be done, and how the resulting data are used to estimate the stockpile's current and future reliability. These issues are particularly critical from a planning perspective: given what has already been observed and our understanding of the mechanisms of stockpile aging, what is an appropriate and cost-effective surveillance program? Surveillance programs are costly, broad, and deep, especially in the DOE, where the US nuclear weapons surveillance program must 'ensure, through various tests, that the reliability of nuclear weapons is maintained' in the absence of full-system testing (General Accounting Office, 1996). The DOE program consists primarily of three types of tests: nonnuclear flight tests, that involve the actual dropping or launching of a weapon from which the nuclear components have been removed; and nonnuclear and nuclear systems laboratory tests, which detect defects due to aging, manufacturing, and design of the nonnuclear and nuclear portions of the weapons. Fully integrated analysis of the suite of nuclear weapons surveillance data is an ongoing area of research (Wilson et al., 2007). This paper introduces a simple model that captures high-level features of stockpile reliability over time and can be used to answer broad policy questions about surveillance programs. Our intention is to provide a framework that generates tractable answers that

  12. Reliable H∞ filtering for discrete piecewise linear systems with infinite distributed delays

    NASA Astrophysics Data System (ADS)

    Wei, Guoliang; Han, Fei; Wang, Licheng; Song, Yan

    2014-05-01

    This paper is concerned with the reliable H∞ filtering problem for discrete-time piecewise linear systems subject to sensor failures and time delays. The considered sensor failures are depicted by bounded variables taking value on a certain interval. The time delays are assumed to be infinitely distributed in the discrete-time domain. The purpose of the addressed reliable H∞ filtering problem is to design a piecewise linear filter such that, for the admissible sensor failures and possible infinite distributed delays, the augmented dynamics is exponentially stable and the H∞ performance is guaranteed with a prescribed attenuation level γ. With the aid of the convex optimal method, the filter parameters are obtained in terms of the solution to a set of LMIs which can be solved by the Matlab Toolbox. At last, an illustrative simulation is presented to demonstrate the effectiveness and applicability of the proposed algorithms.

  13. Reliability of high power diode laser systems based on single emitters

    NASA Astrophysics Data System (ADS)

    Leisher, Paul; Reynolds, Mitch; Brown, Aaron; Kennedy, Keith; Bao, Ling; Wang, Jun; Grimshaw, Mike; DeVito, Mark; Karlsen, Scott; Small, Jay; Ebert, Chris; Martinsen, Rob; Haden, Jim

    2011-03-01

    Diode laser modules based on arrays of single emitters offer a number of advantages over bar-based solutions including enhanced reliability, higher brightness, and lower cost per bright watt. This approach has enabled a rapid proliferation of commercially available high-brightness fiber-coupled diode laser modules. Incorporating ever-greater numbers of emitters within a single module offers a direct path for power scaling while simultaneously maintaining high brightness and minimizing overall cost. While reports of long lifetimes for single emitter diode laser technology are widespread, the complex relationship between the standalone chip reliability and package-induced failure modes, as well as the impact of built-in redundancy offered by multiple emitters, are not often discussed. In this work, we present our approach to the modeling of fiber-coupled laser systems based on single-emitter laser diodes.

  14. A Step Made Toward Designing Microelectromechanical System (MEMS) Structures With High Reliability

    NASA Technical Reports Server (NTRS)

    Nemeth, Noel N.

    2003-01-01

    The mechanical design of microelectromechanical systems-particularly for micropower generation applications-requires the ability to predict the strength capacity of load-carrying components over the service life of the device. These microdevices, which typically are made of brittle materials such as polysilicon, show wide scatter (stochastic behavior) in strength as well as a different average strength for different sized structures (size effect). These behaviors necessitate either costly and time-consuming trial-and-error designs or, more efficiently, the development of a probabilistic design methodology for MEMS. Over the years, the NASA Glenn Research Center s Life Prediction Branch has developed the CARES/Life probabilistic design methodology to predict the reliability of advanced ceramic components. In this study, done in collaboration with Johns Hopkins University, the ability of the CARES/Life code to predict the reliability of polysilicon microsized structures with stress concentrations is successfully demonstrated.

  15. Implementation of a combined algorithm designed to increase the reliability of information systems: simulation modeling

    NASA Astrophysics Data System (ADS)

    Popov, A.; Zolotarev, V.; Bychkov, S.

    2016-11-01

    This paper examines the results of experimental studies of a previously submitted combined algorithm designed to increase the reliability of information systems. The data that illustrates the organization and conduct of the studies is provided. Within the framework of a comparison of As a part of the study conducted, the comparison of the experimental data of simulation modeling and the data of the functioning of the real information system was made. The hypothesis of the homogeneity of the logical structure of the information systems was formulated, thus enabling to reconfigure the algorithm presented, - more specifically, to transform it into the model for the analysis and prediction of arbitrary information systems. The results presented can be used for further research in this direction. The data of the opportunity to predict the functioning of the information systems can be used for strategic and economic planning. The algorithm can be used as a means for providing information security.

  16. Reliability-Based Design of a Safety-Critical Automation System: A Case Study

    NASA Technical Reports Server (NTRS)

    Carroll, Carol W.; Dunn, W.; Doty, L.; Frank, M. V.; Hulet, M.; Alvarez, Teresa (Technical Monitor)

    1994-01-01

    In 1986, NASA funded a project to modernize the NASA Ames Research Center Unitary Plan Wind Tunnels, including the replacement of obsolescent controls with a modern, automated distributed control system (DCS). The project effort on this system included an independent safety analysis (ISA) of the automation system. The purpose of the ISA was to evaluate the completeness of the hazard analyses which had already been performed on the Modernization Project. The ISA approach followed a tailoring of the risk assessment approach widely used on existing nuclear power plants. The tailoring of the nuclear industry oriented risk assessment approach to the automation system and its role in reliability-based design of the automation system is the subject of this paper.

  17. Reliable and reproducible classification system for scoliotic radiograph using image processing techniques.

    PubMed

    Anitha, H; Prabhu, G K; Karunakar, A K

    2014-11-01

    Scoliosis classification is useful for guiding the treatment and testing the clinical outcome. State-of-the-art classification procedures are inherently unreliable and non-reproducible due to technical and human judgmental error. In the current diagnostic system each examiner will have diagrammatic summary of classification procedure, number of scoliosis curves, apex level, etc. It is very difficult to define the required anatomical parameters in the noisy radiographs. The classification system demands automatic image understanding system. The proposed automated classification procedures extracts the anatomical features using image processing and applies classification procedures based on computer assisted algorithms. The reliability and reproducibility of the proposed computerized image understanding system are compared with manual and computer assisted system using Kappa values.

  18. Reliability analysis of repairable systems using Petri nets and vague Lambda-Tau methodology.

    PubMed

    Garg, Harish

    2013-01-01

    The main objective of the paper is to developed a methodology, named as vague Lambda-Tau, for reliability analysis of repairable systems. Petri net tool is applied to represent the asynchronous and concurrent processing of the system instead of fault tree analysis. To enhance the relevance of the reliability study, vague set theory is used for representing the failure rate and repair times instead of classical(crisp) or fuzzy set theory because vague sets are characterized by a truth membership function and false membership functions (non-membership functions) so that sum of both values is less than 1. The proposed methodology involves qualitative modeling using PN and quantitative analysis using Lambda-Tau method of solution with the basic events represented by intuitionistic fuzzy numbers of triangular membership functions. Sensitivity analysis has also been performed and the effects on system MTBF are addressed. The methodology improves the shortcomings of the existing probabilistic approaches and gives a better understanding of the system behavior through its graphical representation. The washing unit of a paper mill situated in a northern part of India, producing approximately 200 ton of paper per day, has been considered to demonstrate the proposed approach. The results may be helpful for the plant personnel for analyzing the systems' behavior and to improve their performance by adopting suitable maintenance strategies.

  19. User's guide to SOLREI: A simulation of reliability and availability of photovoltaic systems

    NASA Astrophysics Data System (ADS)

    Stember, L. H.; Huss, W. R.

    1983-01-01

    The SOLREL is a computer based simulation for analyzing the reliability and availability of PV systems. It provides a tool to model their functional behavior and the effects of component and system reliability. It predicts annual maintenance costs and the annual production of power for photovoltaic power systems. The effects are measured by the resulting change in life cycle costs or life cycle energy costs. The Guide's contents are as follows: It summarizes problems SOLREL can address and provides a description of the potential impact and use of the model; overviews the modeling approach, including how it incorporates degradation, failures and repairs; sample outputs from SOLREL are included; results of the application of SOLREL to a commercial concentrator and a residential flat panel PV system are presented; the use of SOLREL in sensitivity analysesl is discussed; several approaches to testing various design alternatives are given; format information to guide the preparation of input data and a comprehensive, annotated listing of the SOLREL software for a flat panel system are included.

  20. Performances and reliability predictions of optical data transmission links using a system simulator for aerospace applications

    NASA Astrophysics Data System (ADS)

    Bechou, L.; Deshayes, Y.; Aupetit-Berthelemot, C.; Guerin, A.; Tronche, C.

    Space missions for Earth Observation are called upon to carry a growing number of instruments in their payload, whose performances are increasing. Future space systems are therefore intended to generate huge amounts of data and a key challenge in coming years will therefore lie in the ability to transmit that significant quantity of data to ground. Thus very high data rate Payload Telemetry (PLTM) systems will be required to face the demand of the future Earth Exploration Satellite Systems and reliability is one of the major concern of such systems. An attractive approach associated with the concept of predictive modeling consists in analyzing the impact of components malfunctioning on the optical link performances taking into account the network requirements and experimental degradation laws. Reliability estimation is traditionally based on life-testing and a basic approach is to use Telcordia requirements (468GR) for optical telecommunication applications. However, due to the various interactions between components, operating lifetime of a system cannot be taken as the lifetime of the less reliable component. In this paper, an original methodology is proposed to estimate reliability of an optical communication system by using a dedicated system simulator for predictive modeling and design for reliability. At first, we present frameworks of point-to-point optical communication systems for space applications where high data rate (or frequency bandwidth), lower cost or mass saving are needed. Optoelectronics devices used in these systems can be similar to those found in terrestrial optical network. Particularly we report simulation results of transmission performances after introduction of DFB Laser diode parameters variations versus time extrapolated from accelerated tests based on terrestrial or submarine telecommunications qualification standards. Simulations are performed to investigate and predict the consequence of degradations of the Laser diode (acting as a