Reliability demonstration for safety-critical systems

This paper suggests a new model for reliability demonstration of safety-critical systems, based on the TRW Software Reliability Theory. The paper describes the model; the test equipment required and test strategies based on the various constraints occurring during software development. The paper also compares a new testing method, Single Risk Sequential Testing (SRST), with the standard Probability Ratio Sequential Testing method (PRST), and concludes that: • SRST provides higher chances of success than PRST • SRST takes less time to complete than PRST • SRST satisfies the consumer risk criterion, whereas PRST provides a much smaller consumer risk than the requirement

An optimal statistical testing policy for software reliability demonstration of safety-critical systems

When software reliability demonstration of safety-critical systems by statistical testing is treated as a Test, Analyse and Fix (TAAF) process, an optimal testing policy can be found, which maximises the probability of success of the whole process, over a pre-determined period of time. The optimisation problem is formulated, solved by stochastic dynamic programming, and demonstrated by two numerical examples

Validation of Ultrahigh Dependability for Software-Based Systems

Modern society depends on computers for a number of critical tasks in which failure can have very high costs. As a consequence, high levels of dependability (reliability, safety, etc.) are required from such computers, including their software. Whenever a quantitative approach to risk is adopted, these requirements must be stated in quantitative terms, and a rigorous demonstration of their being attained is necessary. For software used in the most critical roles, such demonstrations are not usually supplied. The fact is that the dependability requirements often lie near the limit of the current state of the art, or beyond, in terms not only of the ability to satisfy them, but also, and more often, of the ability to demonstrate that they are satisfied in the individual operational products (validation). We discuss reasons why such demonstrations cannot usually be provided with the means available: reliability growth models, testing with stable reliability, structural dependability modelling, as well as more informal arguments based on good engineering practice. We state some rigorous arguments about the limits of what can be validated with each of such means. Combining evidence from these different sources would seem to raise the levels that can be validated; yet this improvement is not such as to solve the problem. It appears that engineering practice must take into account the fact that no solution exists, at present, for the validation of ultra-high dependability in systems relying on complex software

Pipeline Inspection Technologies Demonstration Report Final

The pipeline infrastructure is a critical element in the energy delivery system across the United States. Its failure can affect both public health and safety directly and indirectly through impacts on the energy supply. The pipeline infrastructure is aging, while at the same time Research & Development (R&D) funding from the pipeline industry to develop technologies to assure its integrity is experiencing budgetary constraints. Total R&D funding is being further reduced through the elimination of programs resulting from restructuring within the government and energy industry. The Pipeline & Hazardous Materials Safety Administration (PHMSA), Pipeline Safety R&D Program mission is to ensure the safe, reliable & environmentally sound operation of the nation’s pipeline transportation system. With passage of the Pipeline Safety Improvement Act (PSIA) in 2002, industry is now required to invest significantly more capital to inspect and maintain their systems. The PSIA requires enhanced maintenance programs and continuing integrity inspection of all pipelines located within “high consequence areas” where a pipeline failure could threaten public safety, property and the environment. According to the Interstate Natural Gas Association of America (INGAA) the cost to industry to implement the PSIA in the first ten years will exceed $2 billion. The focus of the PHMSA Pipeline Safety R&D Program is to sponsor research and development projects intended on providing near-term solutions that will improve the safety, reduce environmental impact, and enhance the reliability of the nation’s pipeline transportation system. Conducting infield technology demonstration test to facilitate technology transfer from government funded R&D programs strengthens communication and coordination with industry stakeholders The PHMSA Pipeline Safety R&D Program role in technology development and innovation has increased with the passage of the Pipeline Safety Improvement Act of 2002. The implementation of the Integrity Management Program for natural gas and hazardous liquids has focused efforts on proactively finding and fixing safety-related problems. For several years the PHMSA Pipeline Safety R&D Program along with the DOE/NETL, Gas Delivery Reliability Program have funded the development of advanced in-line inspection (ILI) technologies to detect mechanical damage, corrosion and other threats to pipeline integrity. Several projects have matured to a stage where demonstrations of their detection capability are now warranted. During the week of January 9th, 2006, the PHMSA Pipeline Safety R&D Program and the DOE/NETL, Gas Delivery Reliability Program co-sponsored a demonstration of six innovative technologies. The demonstrations were conducted at Battelle West Jefferson’s Pipeline Simulation Facility (PSF) near Columbus, Ohio. The pipes used in the demonstration were prepared by Battelle at the PSF and each was pre-calibrated to establish baseline defect measurements. Each technology performed a series of pipeline inspection runs to determine their capability to detect and size mechanical damage, corrosion, stress corrosion cracking or plastic pipe defects. Overall, each technology performed well in their assessment category

Pipeline Inspection Technologies Demonstration Report Final

The pipeline infrastructure is a critical element in the energy delivery system across the United States. Its failure can affect both public health and safety directly and indirectly through impacts on the energy supply. The pipeline infrastructure is aging, while at the same time Research & Development (R&D) funding from the pipeline industry to develop technologies to assure its integrity is experiencing budgetary constraints. Total R&D funding is being further reduced through the elimination of programs resulting from restructuring within the government and energy industry. The Pipeline & Hazardous Materials Safety Administration (PHMSA), Pipeline Safety R&D Program mission is to ensure the safe, reliable & environmentally sound operation of the nation’s pipeline transportation system. With passage of the Pipeline Safety Improvement Act (PSIA) in 2002, industry is now required to invest significantly more capital to inspect and maintain their systems. The PSIA requires enhanced maintenance programs and continuing integrity inspection of all pipelines located within “high consequence areas” where a pipeline failure could threaten public safety, property and the environment. According to the Interstate Natural Gas Association of America (INGAA) the cost to industry to implement the PSIA in the first ten years will exceed $2 billion. The focus of the PHMSA Pipeline Safety R&D Program is to sponsor research and development projects intended on providing near-term solutions that will improve the safety, reduce environmental impact, and enhance the reliability of the nation’s pipeline transportation system. Conducting infield technology demonstration test to facilitate technology transfer from government funded R&D programs strengthens communication and coordination with industry stakeholders The PHMSA Pipeline Safety R&D Program role in technology development and innovation has increased with the passage of the Pipeline Safety Improvement Act of 2002. The implementation of the Integrity Management Program for natural gas and hazardous liquids has focused efforts on proactively finding and fixing safety-related problems. For several years the PHMSA Pipeline Safety R&D Program along with the DOE/NETL, Gas Delivery Reliability Program have funded the development of advanced in-line inspection (ILI) technologies to detect mechanical damage, corrosion and other threats to pipeline integrity. Several projects have matured to a stage where demonstrations of their detection capability are now warranted. During the week of January 9th, 2006, the PHMSA Pipeline Safety R&D Program and the DOE/NETL, Gas Delivery Reliability Program co-sponsored a demonstration of six innovative technologies. The demonstrations were conducted at Battelle West Jefferson’s Pipeline Simulation Facility (PSF) near Columbus, Ohio. The pipes used in the demonstration were prepared by Battelle at the PSF and each was pre-calibrated to establish baseline defect measurements. Each technology performed a series of pipeline inspection runs to determine their capability to detect and size mechanical damage, corrosion, stress corrosion cracking or plastic pipe defects. Overall, each technology performed well in their assessment category

High-speed civil transport flight- and propulsion-control technological issues

Technology advances required in the flight and propulsion control system disciplines to develop a high speed civil transport (HSCT) are identified. The mission and requirements of the transport and major flight and propulsion control technology issues are discussed. Each issue is ranked and, for each issue, a plan for technology readiness is given. Certain features are unique and dominate control system design. These features include the high temperature environment, large flexible aircraft, control-configured empennage, minimizing control margins, and high availability and excellent maintainability. The failure to resolve most high-priority issues can prevent the transport from achieving its goals. The flow-time for hardware may require stimulus, since market forces may be insufficient to ensure timely production. Flight and propulsion control technology will contribute to takeoff gross weight reduction. Similar technology advances are necessary also to ensure flight safety for the transport. The certification basis of the HSCT must be negotiated between airplane manufacturers and government regulators. Efficient, quality design of the transport will require an integrated set of design tools that support the entire engineering design team

A Methodology for Safety Case Development

This paper will outline a safety case methodology that seeks to minimise safety risks and commercial risks by constructing a demonstrable safety case. The safety case ideas presented here were initially developed in an EU-sponsored SHIP project [1] and was then further developed in the UK Nuclear Safety Research Programme (the QUARC Project [2]). Some of these concepts have subsequently been incorporated in safety standards such as MOD Def Stan 00-55, and have also been used to establish specific safety cases for clients. A generalisation of the concepts also appears in Def Stan 00-42 Part 2, in the form of the software reliability case