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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 577 records · Page 32
All sourcesNASA NTRSDOE OSTI
NASA NTRS1989

Three approaches to reliability analysis

It is noted that current reliability analysis tools differ not only in their solution techniques, but also in their approach to model abstraction. The analyst must be satisfied with the constraints that are intrinsic to any combination of solution technique and model abstraction. To get a better idea of the nature of these constraints, three reliability analysis tools (HARP, ASSIST/SURE, and CAME) were used to model portions of the Integrated Airframe/Propulsion Control System architecture. When presented with the example problem, all three tools failed to produce correct results. In all cases, either the tool or the model had to be modified. It is suggested that most of the difficulty is rooted in the large model size and long computational times which are characteristic of Markov model solutions.

Mesh networks↗
NASA NTRS1990

State reduction for semi-Markov reliability models

Semi-Markov processes have proved to be an effective and convenient tool to construct models of systems that achieve reliability by redundancy and reconfiguration. These models are able to depict complex system architectures and to capture the dynamics of fault arrival and system recovery. A disadvantage of this approach is that the models can be extremely large, which poses both a model construction and a computational problem. Techniques are needed to reduce the model size. Because these systems are used in critical applications where failure can be expensive, there must be an analytically derived bound for the error produced by the model reduction technique. Automatic model generation programs have been written to help the reliability analyst produce models of complex systems. Because of the importance of these programs, the model reduction technique needs to be precise and easily implemented. This paper presents a model reduction technique called trimming that can be applied to a popular class of systems. An error bound for the trimming procedure is derived that uses readily available system parameters. The trimming procedure is precisely described and appears easy to implement in a model generation program.

Reduced order systems↗
NASA NTRS1962

RELIABILITY PROGRAMS FOR ''L'' SYSTEMS

The AFSC Program Structure assigns numbers and letters to the various programs in order to identify the efforts for management control. The fact that most of the command and control systems have the designator "L" affixed has prompted the reference to them as the "L" systems. In this paper the mission of "L" systems has been described, the complexity of the equipment indicated, and the importance of these systems to our national defense efforts pointed out. The efforts by the Electronic Systems Division to comply With the Air Force policy that a comprehensive reliability program be required for each contract to assure delivery of reliable systems and equipment to the Air Force inventory are described in considerable detail.

RELIABILITY↗
NASA NTRS1965

NASA'S reliability requirements.

NASA reliability program provisions for space system contractors, detailing program management, reliability engineering, testing and evaluation

PROGRAM MANAGEMENT↗
NASA NTRS1999

Panel: Practical Issues in Implementing Software Reliability Measurement

Many ways of estimating software systems' reliability, or reliability-related quantities, have been developed over the past several years. In this panel, we discuss practical issues to be addressed in implementing software reliabilty measurement techniques in a production development environment.

software reliability software measurement software↗
NASA NTRS1998

Key Factors on CSP Assembly Reliability

Although the weakest link of CSP assembly reliability has been often internal package failure, solder joint fatigue is still considered to be the key factor for reliability.

CSP assembly reliability solder joints↗
NASA NTRS1996

Methodology for Physics and Engineering of Reliable Products

Physics of failure approaches have gained wide spread acceptance within the electronic reliability community. These methodologies involve identifying root cause failure mechanisms, developing associated models, and utilizing these models to inprove time to market, lower development and build costs and higher reliability. The methodology outlined herein sets forth a process, based on integration of both physics and engineering principles, for achieving the same goals.

failure analysis electronics reliability PACT (pre↗
NASA NTRS1997

Reliability Investigation of Ball Grid Array Assemblies for Space Flight Applications

JPL, in a partnership with an industrial consortium, is currently engaged in the investigation of reliability and quality issues if ball grid array (BGA) packages as they may be applied to space flight electronics. Performing tests to determine the solder joint reliability of assemblies using BGAs under temperature cycling has proved to be a real challenge for test engineers.

Ball grid array printed wiring assemblies reliabil↗
NASA NTRS2004

Formal methods and software reliability

In this position statement I briefly describe how the software reliability problem has changed over the years, and the primary reasons for the recent creation of the Laboratory for Reliable Software at JPL.

software reliability↗