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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.
Forecasting and Market Design Advances: Supporting an Increasing Share of Renewable Energy
Electricity systems around the world are decarbonizing, driven by reductions in the cost of renewable energy and encouraged by supportive regulatory policy. Electricity market designs are increasingly being tested to ensure that the bulk power system can deliver reliable, cost-effective energy to all consumers.
Standby redundancy system as a particular case of systems with possible structural faults
Reliability of redundancy system with possible structural fault
The use of automatic programming techniques for fault tolerant computing systems
It is conjectured that the production of software for ultra-reliable computing systems such as required by Space Station, aircraft, nuclear power plants and the like will require a high degree of automation as well as fault tolerance. In this paper, the relationship between automatic programming techniques and fault tolerant computing systems is explored. Initial efforts in the automatic synthesis of code from assertions to be used for error detection as well as the automatic generation of assertions and test cases from abstract data type specifications is outlined. Speculation on the ability to generate truly diverse designs capable of recovery from errors by exploring alternate paths in the program synthesis tree is discussed. Some initial thoughts on the use of knowledge based systems for the global detection of abnormal behavior using expectations and the goal-directed reconfiguration of resources to meet critical mission objectives are given. One of the sources of information for these systems would be the knowledge captured during the automatic programming process.
The reliability analysis of a separated, dual fail operational redundant strapdown IMU
A methodology for quantitatively analyzing the reliability of redundant avionics systems, in general, and the dual, separated Redundant Strapdown Inertial Measurement Unit (RSDIMU), in particular, is presented. The RSDIMU is described and a candidate failure detection and isolation system presented. A Markov reliability model is employed. The operational states of the system are defined and the single-step state transition diagrams discussed. Graphical results, showing the impact of major system parameters on the reliability of the RSDIMU system, are presented and discussed.
Reliability Assessment of Reconfigurable Flight Control Systems Using Sure and Assist
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).
Research on failure free systems Final report
Development and testing of integrated circuits and redundant systems for circuit reliability and failure free systems
Design, Development, Testing, and Evaluation: Human Factors Engineering
While human-system interaction occurs in all phases of system development and operation, this chapter on Human Factors in the DDT&E for Reliable Spacecraft Systems is restricted to the elements that involve "direct contact" with spacecraft systems. Such interactions will encompass all phases of human activity during the design, fabrication, testing, operation, and maintenance phases of the spacecraft lifespan. This section will therefore consider practices that would accommodate and promote effective, safe, reliable, and robust human interaction with spacecraft systems. By restricting this chapter to what the team terms "direct contact" with the spacecraft, "remote" factors not directly involved in the development and operation of the vehicle, such as management and organizational issues, have been purposely excluded. However, the design of vehicle elements that enable and promote ground control activities such as monitoring, feedback, correction and reversal (override) of on-board human and automation process are considered as per NPR8705.2A, Section 3.3.
Advanced eLectrical Bus (ALBus) CubeSat: From Build to Flight
Advanced eLectrical Bus (ALBus) CubeSat is a technology demonstration mission of a 3-U CubeSat with an advanced digitally controlled electrical power system and novel use of Shape Memory Alloy (SMA) technology for reliable deployable solar array mechanisms. The primary objective was to advance the power management and distribution (PMAD) capabilities to enable future missions requiring more flexible and reliable power systems with higher output power capabilities. Goals included demonstration of 100W distribution to a target electrical load, response to continuous and fast transient power requirements, and exhibition of reliable deployment of solar arrays and antennas utilizing re-settable SMA mechanisms. The power distribution function of the ALBus PMAD system is unique in the total power to target load capability, as power is distributed from batteries to provide 100W of power directly to a resistive load. The deployable solar arrays utilize NASA’s Nickel-Titanium-Palladium-Platinum (NiTiPdPt) high-temperature SMAs for the retention and release mechanism, and a superelastic binary NiTi alloy for the hinge component. The project launched as part of the CubeSat Launch Initiative (CLI) Educational Launch of Nanosatellites (ELaNa) XIX mission on Rocket Lab’s Electron in December 2018. This paper summarizes the final launched design and the lessons learned from build to flight.
Solid state sequencer system, phase 2. Appendix C - Reliability analysis, volume 4 Summary report
Reliability analysis and performance prediction for solid state sequencer system model
Developing an Approach for Analyzing and Verifying System Communication
This slide presentation reviews a project for developing an approach for analyzing and verifying the inter system communications. The motivation for the study was that software systems in the aerospace domain are inherently complex, and operate under tight constraints for resources, so that systems of systems must communicate with each other to fulfill the tasks. The systems of systems requires reliable communications. The technical approach was to develop a system, DynSAVE, that detects communication problems among the systems. The project enhanced the proven Software Architecture Visualization and Evaluation (SAVE) tool to create Dynamic SAVE (DynSAVE). The approach monitors and records low level network traffic, converting low level traffic into meaningful messages, and displays the messages in a way the issues can be detected.
Effects of Surface Treatments on Stainless Steel 316 Exposed to Potable Water Containing Silver Disinfectant
Silver has been selected as the forward disinfectant candidate for potable water systems in future space exploration missions. To develop a reliable antibacterial system that requires minimal maintenance, it is necessary to address relevant challenges to preclude problems for future missions. One such challenge is silver depletion in potable water systems. When in contact with various materials, silver ions can be easily reduced to silver metal or form insoluble compounds. The same chemical properties that make ionic silver a powerful antimicrobial agent also result in its quick inactivation or depletion in various environments. Different metal surface treatments, such as thermal oxidation and electropolishing, have been investigated for their effectiveness in reducing silver disinfectant depletion in potable water. However, their effects on the metal surface microstructure and chemical resistance have not often been included in the studies. This paper reports the effects of surface treatments on stainless steel 316 (SS316) exposed to potable water containing silver ion as a disinfectant. Early experimental results showed that thermal oxidation, when compared with electropolishing, resulted in a thicker oxide layer but compromised the corrosion resistance of SS316.
Design, Formalization, and Verification of Decision Making for Intelligent Systems
The development of autonomous systems requires a rigorous process that can guarantee a system’s reliability in critical applications. At its core, an autonomous system bases its behavior on a well-defined decision making system. In this paper, we present a methodological basis for the design, formalization and formal verification of Decision Making systems for autonomous agents. The approach is generally applicable to operational objectives that can be functionally decomposed and subsequently represented as Hierarchical Finite State Machines. As a case study, we present the application of this method to implement a Decision Making model in Simulink. Furthermore, we present how we use NASA’s FRET tool to write requirements in structured natural language and generate formal specifications that can be automatically digested by NASA’s CoCoSim tool. Finally, we present how, by leveraging CoCoSim, we perform formal verification against the Simulink model and present analysis results.
Design, Formalization, and Verification of Decision Making for Intelligent Systems
The development of autonomous systems requires a rigorous process that can guarantee a system’s reliability in critical applications. At its core, an autonomous system bases its behavior on a well-defined decision making system. In this paper, we present a methodological basis for the design, formalization and formal verification of Decision Making systems for autonomous agents. The approach is generally applicable to operational objectives that can be functionally decomposed and subsequently represented as Hierarchical Finite State Machines. As a case study, we present the application of this method to implement a Decision Making model in Simulink. Furthermore, we present how we use NASA’s FRET tool to write requirements in structured natural language and generate formal specifications that can be automatically digested by NASA’s CoCoSim tool. Finally, we present how, by leveraging CoCoSim, we perform formal verification against the Simulink model and present analysis results.
Quantitative evaluation of operator in a 'man-machine' system
Quantitative evaluation of operator reliability in man-machine system
Hazard Analysis to Support Fusion Systems Safety Assessments
Reliability, safety, and performance are vital aspects of any nuclear operation. Fusion technology continues to grow in public, private, and research interest, and coupled with rapidly growing energy needs, fusion technology research is poised for fast progress. The development of a Fusion Nuclear Science Facility (FNSF) is seen as stepping stone for demonstrating long-cycle fusion. Naturally, such operation requires systems that are available, reliable, and safe. This work provides a novel demonstration of systems theory coupled with traditional hazard analysis to provide insights into the risk priority of components and systems found within the FNSF. The results of this work are a set of identified hazards that should be considered for the risk-informed design and development of the FNSF.
Model-Driven Development of Reliable Avionics Architectures for Lunar Surface Systems
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.