2,090 Matching Results

Search Results

Advanced search parameters have been applied.

Reliability of Electronics

Description: The purpose of this research is not to research new technology but how to improve existing technology and understand how the manufacturing process works. Reliability Engineering fall under the category of Quality Control and uses predictions through statistical measurements and life testing to figure out if a specific manufacturing technique will meet customer satisfaction. The research also answers choice of materials and choice of manufacturing process to provide a device that will not only meet but exceed customer demand. Reliability Engineering is one of the final testing phases of any new product development or redesign.
Date: December 2014
Creator: Wickstrom, Larry E.
Partner: UNT Libraries

A Study on the System Reliability of Cold-Formed Steel Roof Trusses

Description: This thesis presents a research project aimed at advancing the treatment of cold-formed steel (CFS) structural reliability in roof trusses. Structural design today relies almost exclusively on component-level design, so structural safety is assured by limiting the probability of failure of individual components. Reliability of the entire system is typically not assessed, so in a worst-case scenario the system reliability may be less than the component reliability, or in a best-case scenario the system reliability may be much greater than the component reliability. A roof truss itself, is a subsystem with several possible failure modes that are being studied in this test program. These trusses are constructed of CFS members that nest with one another at the truss nodes and are connected by drilling fasteners through the mated surfaces, as well as having steel sheathing fastened to the top chords for lateral bracing. Presented in this paper is a series of full-scale static tests on single cold-formed steel roof trusses with a unique experimental setup. The test specimens were carefully monitored to address multiple failure modes: buckling of the top chord, buckling of the truss webs, and any connection failures. This research includes the experimental results, the computed system reliability of the trusses as well as their relationship between the components reliability.
Date: May 2017
Creator: Johnson, Adam
Partner: UNT Libraries

Review of the Recent Frequency Performance of the Eastern, Western and ERCOT Interconnections

Description: The reliable operation of an electric power system depends on careful management of the balance between generation and load to ensure that system frequency is maintained within narrow bounds around a scheduled value. Yet, maintaining frequency at the scheduled value is challenging because the load served is continuously changing, and occasionally, events such as the sudden loss of a large generation plant or large amount of load, cause frequency to deviate abruptly. This report reviews the recent history of frequency performance for all three U.S. interconnections: Eastern, Western, and the Electric Reliability Council of Texas (ERCOT). The review is based on data collected by the North American Electric Reliability Corporation (NERC). The review focuses on frequency response, which measures the performance of the interconnections immediately following sudden, large imbalances between load and generation. Trends in frequency response are presented and preliminary efforts are made to relate frequency response to other aspects of frequency performance and to examine aspects of the methods used to calculate frequency response.
Date: December 20, 2010
Creator: Lacommare, Kristina S H
Partner: UNT Libraries Government Documents Department

Fifty Years of THERP and Human Reliability Analysis

Description: In 1962 at a Human Factors Society symposium, Alan Swain presented a paper introducing a Technique for Human Error Rate Prediction (THERP). This was followed in 1963 by a Sandia Laboratories monograph outlining basic human error quantification using THERP and, in 1964, by a special journal edition of Human Factors on quantification of human performance. Throughout the 1960s, Swain and his colleagues focused on collecting human performance data for the Sandia Human Error Rate Bank (SHERB), primarily in connection with supporting the reliability of nuclear weapons assembly in the US. In 1969, Swain met with Jens Rasmussen of Risø National Laboratory and discussed the applicability of THERP to nuclear power applications. By 1975, in WASH-1400, Swain had articulated the use of THERP for nuclear power applications, and the approach was finalized in the watershed publication of the NUREG/CR-1278 in 1983. THERP is now 50 years old, and remains the most well known and most widely used HRA method. In this paper, the author discusses the history of THERP, based on published reports and personal communication and interviews with Swain. The author also outlines the significance of THERP. The foundations of human reliability analysis are found in THERP: human failure events, task analysis, performance shaping factors, human error probabilities, dependence, event trees, recovery, and pre- and post-initiating events were all introduced in THERP. While THERP is not without its detractors, and it is showing signs of its age in the face of newer technological applications, the longevity of THERP is a testament of its tremendous significance. THERP started the field of human reliability analysis. This paper concludes with a discussion of THERP in the context of newer methods, which can be seen as extensions of or departures from Swain’s pioneering work.
Date: June 1, 2012
Creator: Boring, Ronald L.
Partner: UNT Libraries Government Documents Department


Description: The purpose of this paper is twofold: to introduce the reader to the subject of instabilities exhibited by relativistic particle beams, and to summarize the present state of our knowledge concerning these phenomena. Most of the material in the first part of the paper is not new. It has been known to some specialists for a good many years; what is new is that the problems that can be solved are now of much more interest to the general community of accelerator physicists. Consequently, many accelerator physicists who have not paid much attention to these matters may now want to become informed; it is my hope that this paper will provide an introduction to the field. The second part of the article consists of two sections. The first summarizes the experimental information presently available, with emphasis upon the degree to which it confirms or disagrees with theory. Our current level of understanding is delineated: considering the generality and reliability of the theoretical analysis as well as the degree of experimental confirmation, the author expresses his opinion as to what can be considered relatively well established. The final section contains a discussion of subjects needing further investigation and, consequently, supplements the discussion of areas of understanding by describing the peripheral areas of uncertainty.
Date: October 4, 1965
Creator: Sessler, Andrew M.
Partner: UNT Libraries Government Documents Department

The assumption of a reliable instrument and other pitfalls to avoid when considering the reliability of data

Description: This article helps researchers avoid common pitfalls associated with reliability including incorrectly assuming that measurement error always attenuates observed score correlations, different sources of measurement error originate from the same source, and reliability is a function of instrumentation.
Date: April 12, 2012
Creator: Nimon, Kim F.; Zientek, Linda Reichwein & Henson, Robin K.
Partner: UNT College of Arts and Sciences

Renewable Resource Integration Project - Scoping Study of Strategic Transmission, Operations, and Reliability Issues

Description: California is on a path to increase utilization of renewable resources. California will need to integrate approximately 30,000 megawatts (MW) of new renewable generation in the next 20 years. Renewable resources are typically located in remote locations, not near the load centers. Nearly two/thirds or 20,000 MW of new renewable resources needed are likely to be delivered to Los Angeles Basin transmission gateways. Integration of renewable resources requires interconnection to the power grid, expansion of the transmission system capability between the backbone power grid and transmission gateways, and increase in delivery capacity from transmission gateways to the local load centers. To scope the transmission, operations, and reliability issues for renewables integration, this research focused on the Los Angeles Basin Area transmission gateways where most of new renewables are likely. Necessary actions for successful renewables integration include: (1) Expand Los Angeles Basin Area transmission gateway and nomogram limits by 10,000 to 20,000 MW; (2) Upgrade local transmission network for deliverability to load centers; (3) Secure additional storage, demand management, automatic load control, dynamic pricing, and other resources that meet regulation and ramping needed in real time operations; (4) Enhance local voltage support; and (5) Expand deliverability from Los Angeles to San Diego and Northern California.
Date: July 1, 2008
Creator: Eto, Joseph; Budhraja, Vikram; Ballance, John; Dyer, Jim; Mobasheri, Fred & Eto, Joseph
Partner: UNT Libraries Government Documents Department

SAPHIRE 8 New Features and Capabilities

Description: The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) software performs probabilistic risk assessment (PRA) calculations. SAPHIRE is used in support of NRC’s risk-informed programs such as the Accident Sequence Precursor (ASP) program, Management Directive 8.3, “NRC Incident Investigation Program,” or the Significance Determination Process (SDP). It is also used to develop and run the Standardized Plant Analysis Risk (SPAR) models. SAPHIRE Version 8 is a new version of the software with an improved interface and capabilities to support risk-informed programs. SAPHIRE Version 8 is designed to easily handle larger and more complex models. Applications of previous SAPHIRE versions indicated the need to build and solve models with a large number of sequences. Risk assessments that include endstate evaluations for core damage frequency and large, early release frequency evaluations have greatly increased the number of sequences required. In addition, the complexity of the models has increased since risk assessments evaluate both potential internal and external events, as well as different plant operational states. Special features of SAPHIRE 8 help create and run integrated models which may be composed of different model types. SAPHIRE 8 includes features and capabilities that are new or improved over the current Version 7 to address the new requirements for risk-informed programs and SPAR models. These include: • Improved User Interfaces • Model development • Methods • General Support Features
Date: August 1, 2008
Creator: Smith, Curtis
Partner: UNT Libraries Government Documents Department

Application of Entry-Time Processes in Asset Management for Nuclear Power Plants (Final Report)

Description: A mathematical model of entry-time processes was developed, and a computational method for solving that model was verified. This methodology was demonstrated via application to a succession of increasingly more complex subsystems of nuclear power plants. The effort culminated in the application to main generators that constituted the PhD dissertation of Shuwen (“Eric”) Wang. Dr. Wang is now employed by ABS Consulting, in Anaheim, CA. ABS is a principal provider to the nuclear industry of technical services related to reliability and safety.
Date: January 23, 2008
Creator: Nelson, Paul
Partner: UNT Libraries Government Documents Department

Review of HRP Positions

Description: The Department of Energy (DOE) Human Reliability Program (HRP), published as 10 CFR Part 712, is currently being reviewed and revised to address concerns identified during its implementation. Although these ''page changes'' primarily incorporate clarification of terms and language, the following discussion relates to broadening the definition of positions that require HRP certification that is found in {section}712.10.
Date: January 1, 2007
Creator: Studies, Center for Reliability
Partner: UNT Libraries Government Documents Department

Bridging Resilience Engineering and Human Reliability Analysis

Description: There has been strong interest in the new and emerging field called resilience engineering. This field has been quick to align itself with many existing safety disciplines, but it has also distanced itself from the field of human reliability analysis. To date, the discussion has been somewhat one-sided, with much discussion about the new insights afforded by resilience engineering. This paper presents an attempt to address resilience engineering from the perspective of human reliability analysis (HRA). It is argued that HRA shares much in common with resilience engineering and that, in fact, it can help strengthen nascent ideas in resilience engineering. This paper seeks to clarify and ultimately refute the arguments that have served to divide HRA and resilience engineering.
Date: June 1, 2010
Creator: Boring, Ronald L.
Partner: UNT Libraries Government Documents Department

How Many Performance Shaping Factors are Necessary for Human Reliability Analysis?

Description: It has been argued that human reliability analysis (HRA) has expended considerable energy on creating detailed representations of human performance through an increasingly long list of performance shaping factors (PSFs). It is not clear, however, to what extent this refinement and expansion of PSFs has enhanced the quality of HRA. Indeed, there is considerable range in the number of PSFs provided by individual HRA methods, ranging from single factor models such as time-reliability curves, up to 50 or more PSFs in some current HRA models. The US Nuclear Regulatory Commission advocates 15 PSFs in its HRA Good Practices (NUREG-1792), while its SPAR-H method (NUREG/CR-6883) espouses the use of eight PSFs and its ATHEANA method (NUREG-1624) features an open-ended number of PSFs. The apparent differences in the optimal number of PSFs can be explained in terms of the diverse functions of PSFs in HRA. The purpose of this paper is to explore the role of PSFs across different stages of HRA, including identification of potential human errors, modeling of these errors into an overall probabilistic risk assessment, quantifying errors, and preventing errors.
Date: June 1, 2010
Creator: Boring, Ronald L.
Partner: UNT Libraries Government Documents Department

Predicting the reliability of electronic circuits.

Description: Procedures to predict the reliability of electrical circuits are discussed. Three cases are introduced and discussed. In Case 1, an analyst predicts the probability of any failure in the intended relations between circuit inputs and circuit outputs. In Case 2, an analyst predicts the probability that specified unintended outputs would occur. In Case 3, an analyst considers coupling between circuits. Logic models are given for the three cases, and sources of failure probabilities of components are mentioned. Methods of analysis are given, software tools are mentioned, and recommendations for presentation and review of results are discussed.
Date: June 1, 2004
Creator: Loescher, Douglas H.
Partner: UNT Libraries Government Documents Department

SAPHIRE 8 Volume 2 - Technical Reference

Description: The Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) refers to a set of computer programs that were developed to create and analyze probabilistic risk assessment (PRAs). Herein information is provided on the principles used in the construction and operation of Version 8.0 of the SAPHIRE system. This report summarizes the fundamental mathematical concepts of sets and logic, fault trees, and probability. This volume then describes the algorithms used to construct a fault tree and to obtain the minimal cut sets. It gives the formulas used to obtain the probability of the top event from the minimal cut sets, and the formulas for probabilities that apply for various assumptions concerning reparability and mission time. It defines the measures of basic event importance that SAPHIRE can calculate. This volume gives an overview of uncertainty analysis using simple Monte Carlo sampling or Latin Hypercube sampling, and states the algorithms used by this program to generate random basic event probabilities from various distributions. Also covered are enhance capabilities such as seismic analysis, Workspace algorithms, cut set "recovery," end state manipulation, and use of "compound events."
Date: March 1, 2011
Creator: Smith, C. L.; Wood, S. T.; Galyean, W. J.; Schroeder, J. A. & Sattison, M. B.
Partner: UNT Libraries Government Documents Department

Statistical Modeling of Photovoltaic Reliability Using Accelerated Degradation Techniques (Poster)

Description: We introduce a cutting-edge life-testing technique, accelerated degradation testing (ADT), for PV reliability testing. The ADT technique is a cost-effective and flexible reliability testing method with multiple (MADT) and Step-Stress (SSADT) variants. In an environment with limited resources, including equipment (chambers), test units, and testing time, these techniques can provide statistically rigorous prediction of lifetime and other interesting parameters, such as failure rate, warranty time, mean time to failure, degradation rate, activation energy, acceleration factor, and upper limit level of stress. J-V characterization can be used for degradation data and the generalized Eyring model can be used for the thermal-humidity stress condition. The SSADT model can be constructed based on the cumulative damage model (CEM), which assumes that the remaining test united are failed according to cumulative density function of current stress level regardless of the history on previous stress levels.
Date: February 1, 2011
Creator: Lee, J.; Elmore, R. & Jones, W.
Partner: UNT Libraries Government Documents Department

Failure Rate Data Analysis for High Technology Components

Description: Understanding component reliability helps designers create more robust future designs and supports efficient and cost-effective operations of existing machines. The accelerator community can leverage the commonality of its high-vacuum and high-power systems with those of the magnetic fusion community to gain access to a larger database of reliability data. Reliability studies performed under the auspices of the International Energy Agency are the result of an international working group, which has generated a component failure rate database for fusion experiment components. The initial database work harvested published data and now analyzes operating experience data. This paper discusses the usefulness of reliability data, describes the failure rate data collection and analysis effort, discusses reliability for components with scarce data, and points out some of the intersections between magnetic fusion experiments and accelerators.
Date: July 1, 2007
Creator: Cadwallader, L. C.
Partner: UNT Libraries Government Documents Department

Reliability Results of NERSC Systems

Description: 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.
Date: May 27, 2008
Creator: Petascale Data Storage Institute
Partner: UNT Libraries Government Documents Department

Determination of Strength for Reliability Analysis of Multilayer Ceramic Capacitors

Description: A Nanoindenter<sup>TM</sup> equipped with a Vickers indenter was used to measure fracture toughness of Multilayer Capacitors (MLCs) and BaTiO<sub>3</sub> blanks. Strength of blanks of 6.3 x 4.7 x 1.1 mm<sup>3</sup> was measured by performing three-point flexure using a 4 mm support span. The size of the strength limiting pores in the flexure tests was compared to pore sizes measured on polished MLC cross sections, and it was found that much larger pores were present in the 3-point flexure specimens. Strength distributions for the MLCs were generated using the measured fracture toughness values, assuming the measured pores or second phase inclusions were strength limiting.
Date: January 25, 1999
Creator: Breder, K.; Bridge, R.J.; Kirkland, T.P.; Riester, L. & Wereszczak, A.A.
Partner: UNT Libraries Government Documents Department

BER Science Network Requirements Workshop -- July 26-27,2007

Description: The Energy Sciences Network (ESnet) is the primary provider of network connectivity for the US Department of Energy Office of Science, the single largest supporter of basic research in the physical sciences in the United States of America. In support of the Office of Science programs, ESnet regularly updates and refreshes its understanding of the networking requirements of the instruments, facilities, scientists, and science programs that it serves. This focus has helped ESnet to be a highly successful enabler of scientific discovery for over 20 years. In July 2007, ESnet and the Biological and Environmental Research (BER) Program Office of the DOE Office of Science organized a workshop to characterize the networking requirements of the science programs funded by the BER Program Office. These included several large programs and facilities, including Atmospheric Radiation Measurement (ARM) Program and the ARM Climate Research Facility (ACRF), Bioinformatics and Life Sciences Programs, Climate Sciences Programs, the Environmental Molecular Sciences Laboratory at PNNL, the Joint Genome Institute (JGI). National Center for Atmospheric Research (NCAR) also participated in the workshop and contributed a section to this report due to the fact that a large distributed data repository for climate data will be established at NERSC, ORNL and NCAR, and this will have an effect on ESnet. Workshop participants were asked to codify their requirements in a 'case study' format, which summarizes the instruments and facilities necessary for the science and the process by which the science is done, with emphasis on the network services needed and the way in which the network is used. Participants were asked to consider three time scales in their case studies--the near term (immediately and up to 12 months in the future), the medium term (3-5 years in the future), and the long term (greater than 5 years in the future). ...
Date: February 1, 2008
Creator: Tierney, Brian L. & Dart, Eli
Partner: UNT Libraries Government Documents Department

Design and Implementation of an Open, Interoperable AutomatedDemand Response Infrastructure

Description: This paper describes the concept for and lessons from the development and field-testing of an open, interoperable communications infrastructure to support automating demand response (DR). Automating DR allows greater levels of participation and improved reliability and repeatability of the demand response and customer facilities. Automated DR systems have been deployed for critical peak pricing and demand bidding and are being designed for real time pricing. The system is designed to generate, manage, and track DR signals between utilities and Independent System Operators (ISOs) to aggregators and end-use customers and their control systems.
Date: October 1, 2007
Creator: Piette, Mary Ann; Kiliccote, Sila & Ghatikar, Girish
Partner: UNT Libraries Government Documents Department