Improving the Reliability of Decision-Support Systems for Nuclear Emergency Management by Leveraging Software Design Diversity

This paper introduces a novel method of continuous verification of simulation software used in decision-support systems for nuclear emergency management (DSNE). The proposed approach builds on methods from the field of software reliability engineering, such as N-Version Programming, Recovery Blocks, and Consensus Recovery Blocks. We introduce a new acceptance test for dispersion simulation results and a new voting scheme based on taxonomies of simulation results rather than individual simulation results. The acceptance test and the voter are used in a new scheme, which extends the Consensus Recovery Block method by a database of result taxonomies to support machine-learning. This enables the system to learn how to distinguish correct from incorrect results, with respect to the implemented numerical schemes. Considering that decision-support systems for nuclear emergency management are used in a safety-critical application context, the methods introduced in this paper help improve the reliability of the system and the trustworthiness of the simulation results used by emergency managers in the decision making process. The effectiveness of the approach has been assessed using the atmospheric dispersion forecasts of two test versions of the widely used RODOS DSNE system

Evaluation of Job Queuing/Scheduling Software: Phase I Report

The recent proliferation of high performance work stations and the increased reliability of parallel systems have illustrated the need for robust job management systems to support parallel applications. To address this issue, the national Aerodynamic Simulation (NAS) supercomputer facility compiled a requirements checklist for job queuing/scheduling software. Next, NAS began an evaluation of the leading job management system (JMS) software packages against the checklist. This report describes the three-phase evaluation process, and presents the results of Phase 1: Capabilities versus Requirements. We show that JMS support for running parallel applications on clusters of workstations and parallel systems is still insufficient, even in the leading JMS's. However, by ranking each JMS evaluated against the requirements, we provide data that will be useful to other sites in selecting a JMS

IN2GESOFT: Innovation and Integration of Methods for the Development and Quantitative Management of Software Projects TIN2004-06689-C03

This coordinated project intends to introduce new methods in software engineering project management, integrating different quantitative and qualitative technologies in the management processes. The underlying goal to all three subprojects participants is the generation of information adapted for the efficient performance in the directing of the project. The topics that are investigated are related to the capture of decisions in dynam ical environments and complex systems, software testing and the analysis of the manage ment strategies for the process assessment of the software in its different phases of the production. The project sets up a methodological, conceptual framework and supporting tools that facilitate the decision making in the software project management. This allows us to eval uate the risk and uncertainty associated to different alternatives of management before leading them to action. Thus, it is necessary to define a taxonomy of software models so that they reflect the current reality of the projects. Since the software testing is one of the most critical and costly processes directed to guarantee the quality and reliability of the software, we undertake the research on the automation of the process of software testing by means of the development of new technologies test case generation, mainly based in metaheuristic and model checking techniques in the domains of database and internet applications. The software system developed will allow the integration of these technologies, and the management information needed, from the first phases of the cycle of life in the construction of a software product up to the last ones such as regression tests and maintenance. The set of technologies that we investigate include the use of statistical analysis and of experimental design for obtaining metrics in the phase of analysis, the application of the bayesian nets to the decision processes, the application of the standards of process eval uation and quality models, the utilization of metaheuristics algorithms and technologies of prediction to optimize resources, the technologies of visualization to construct control dashboards, hybrid models for the simulation of processes and others

Development of Simulation for Condition Monitoring and Evaluation of Manufacturing Systems

Equipment Condition Management used for predicting the performance parameters required for maintenance decision making was developed. This program predicts the state probabilities and maintenance action recommendation based the predetermined alert levels. The maintenance program software was developed from the derived stable state probability models using algebraic substitution and computation of the breakdown data and operational data of the MTTF, MTTR, λ and µ of these equipment/component(s) at PM and CM states with implementation algorithm. The models were derived using mechanistic modeling technique such that all the relevant variables of the reliability process were accounted for. Validation analysis of this simulation revealed its prediction accuracy of over 99%. Therefore, its use in the monitoring and evaluation of the health conditions of production systems remains very essential. Keywords: Mechanistic model, process parameter, stable state probabilities, prediction algorithm, Equipment Condition Managemen

The safety case and the lessons learned for the reliability and maintainability case

This paper examine the safety case and the lessons learned for the reliability and maintainability case

Use of COTS functional analysis software as an IVHM design tool for detection and isolation of UAV fuel system faults

This paper presents a new approach to the development of health management solutions which can be applied to both new and legacy platforms during the conceptual design phase. The approach involves the qualitative functional modelling of a system in order to perform an Integrated Vehicle Health Management (IVHM) design – the placement of sensors and the diagnostic rules to be used in interrogating their output. The qualitative functional analysis was chosen as a route for early assessment of failures in complex systems. Functional models of system components are required for capturing the available system knowledge used during various stages of system and IVHM design. MADe™ (Maintenance Aware Design environment), a COTS software tool developed by PHM Technology, was used for the health management design. A model has been built incorporating the failure diagrams of five failure modes for five different components of a UAV fuel system. Thus an inherent health management solution for the system and the optimised sensor set solution have been defined. The automatically generated sensor set solution also contains a diagnostic rule set, which was validated on the fuel rig for different operation modes taking into account the predicted fault detection/isolation and ambiguity group coefficients. It was concluded that when using functional modelling, the IVHM design and the actual system design cannot be done in isolation. The functional approach requires permanent input from the system designer and reliability engineers in order to construct a functional model that will qualitatively represent the real system. In other words, the physical insight should not be isolated from the failure phenomena and the diagnostic analysis tools should be able to adequately capture the experience bases. This approach has been verified on a laboratory bench top test rig which can simulate a range of possible fuel system faults. The rig is fully instrumented in order to allow benchmarking of various sensing solution for fault detection/isolation that were identified using functional analysis

Integrating IVHM and Asset Design

Integrated Vehicle Health Management (IVHM) describes a set of capabilities that enable effective and efficient maintenance and operation of the target vehicle. It accounts for the collection of data, conducting analysis, and supporting the decision-making process for sustainment and operation. The design of IVHM systems endeavours to account for all causes of failure in a disciplined, systems engineering, manner. With industry striving to reduce through-life cost, IVHM is a powerful tool to give forewarning of impending failure and hence control over the outcome. Benefits have been realised from this approach across a number of different sectors but, hindering our ability to realise further benefit from this maturing technology, is the fact that IVHM is still treated as added on to the design of the asset, rather than being a sub-system in its own right, fully integrated with the asset design. The elevation and integration of IVHM in this way will enable architectures to be chosen that accommodate health ready sub-systems from the supply chain and design trade-offs to be made, to name but two major benefits. Barriers to IVHM being integrated with the asset design are examined in this paper. The paper presents progress in overcoming them, and suggests potential solutions for those that remain. It addresses the IVHM system design from a systems engineering perspective and the integration with the asset design will be described within an industrial design process