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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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All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Reliability modeling of fault-tolerant computer based systems

Digital fault-tolerant computer-based systems have become commonplace in military and commercial avionics. These systems hold the promise of increased availability, reliability, and maintainability over conventional analog-based systems through the application of replicated digital computers arranged in fault-tolerant configurations. Three tightly coupled factors of paramount importance, ultimately determining the viability of these systems, are reliability, safety, and profitability. Reliability, the major driver affects virtually every aspect of design, packaging, and field operations, and eventually produces profit for commercial applications or increased national security. However, the utilization of digital computer systems makes the task of producing credible reliability assessment a formidable one for the reliability engineer. The root of the problem lies in the digital computer's unique adaptability to changing requirements, computational power, and ability to test itself efficiently. Addressed here are the nuances of modeling the reliability of systems with large state sizes, in the Markov sense, which result from systems based on replicated redundant hardware and to discuss the modeling of factors which can reduce reliability without concomitant depletion of hardware. Advanced fault-handling models are described and methods of acquiring and measuring parameters for these models are delineated.

Bavuso, Salvatore J.↗
NASA NTRSDate not supplied

Students Solving Problems for ISS and Beyond: Inspiring the Next-Generation

Students Solving Problems for ISS and Beyond: Inspiring the Next-Generation Session Title: Students Solving Problems for ISS and Beyond: Inspiring the Next-Generation Session Description: NASA High school students United with NASA to Create Hardware (HUNCH) mission is to empower and inspire students through a Project-Based Learning program where 7-12 grade students learn 21st century skills and can launch their careers through participation in the design and fabrication of real-world valued products for NASA. With six different tracks consisting of Design & Prototype, Culinary Challenge, Softgoods, Precision Machining, Software, and Video Challenge, students are given the opportunity to create solutions for the International Space Station (ISS), the Moon, and beyond. Many projects are requested by the Crew to help ease living conditions, giving students the opportunity to make an impact on the lives of Astronauts. Other projects come directly from NASA and its partners. Join our session to learn how NASA is working with teachers across the country to mentor the next generation of scientists and engineers to solve some of NASA’s greatest challenges. Learning Outcomes: 1. Describe the NASA HUNCH Program, including the program objectives, goals, and strategic partnerships for middle school and high school outreach and advocacy efforts. 2. Identify the innovative strategies NASA is using to work with middle and high school students to solve real-world problems 3. Use the knowledge gained to inspire the next generation of scientists and engineers Session Track: Advocacy & Outreach Specialized Focus Area: Women in Government and Military Learning Level: Foundational Session Format: Listen & Learn Speaker Qualifications: 1. Deboshri Sadhukhan • Current Job Title: Deputy Project Manager • Topic Experience (years of experience related to proposed topic): 1-5 years • Biography: Deboshri Sadhukhan is an engineer for NASA Glenn Research Center (GRC). She has worked on numerous projects — from International Space Station (ISS) fluid technologies, to Orion European Service Module propulsion, to planetary science missions and other game-changing technologies. Her roles have ranged from Project Manager to System Safety Lead. She currently serves as a GRC Regional Mentor for the High school students United with NASA to Create Hardware (HUNCH) program. She also serves as Deputy Project Manager for an ISS payload and Safety & Mission Assurance Lead for a Radioisotope Power Systems project. In these roles, she oversees each phase of a project from beginning to end and provides leadership to increase the reliability, maintainability and system safety of hardware and personnel throughout the system life cycle. She holds a Bachelor of Science in Electrical Engineering from The University of Akron. 2. Nancy Hall • Current Job Title: Project Manager • Topic Experience: 20+ years • Biography: Nancy Rabel Hall earned a B.S. degree in Space Sciences from Florida Institute of Technology and a M.S. degree in Mechanical Engineering from the University of Toledo. She has been at NASA Glenn for over 30 years. She has led several International Space Station experiments that studied how the behavior of fluids and fluid systems behave differently in microgravity as compared to here on Earth. She is also the High school students United with NASA to Create Hardware (HUNCH) project manager, a program that allows students to design and fabricate hardware and softgoods for NASA as well as participate in a culinary and video challenge. She enjoys talking to the public and students about the work being done at NASA as well as showing students how math and science can be fun. She is an amateur radio operator, enjoys playing golf, and reading science fiction and fantasy books.

HUNCH↗
NASA NTRS1987

Computer Reliability

Using a NASA developed program, Dr. J. Walter Bond is creating a course in computer reliability modeling. The course will examine three different computer programs, one of them NASA's Care III, the others UCLA's Aries 78 and Aries 82. All three are designed to help estimate the reliability of complex, redundant, fault tolerant system. In computer design, software of this kind can predict or model the effects of various hardware or software failures, a process called reliability modeling.

Source record↗
NASA NTRS2004

Multisensor Arrays for Greater Reliability and Accuracy

Arrays of multiple, nominally identical sensors with sensor-output-processing electronic hardware and software are being developed in order to obtain accuracy, reliability, and lifetime greater than those of single sensors. The conceptual basis of this development lies in the statistical behavior of multiple sensors and a multisensor-array (MSA) algorithm that exploits that behavior. In addition, advances in microelectromechanical systems (MEMS) and integrated circuits are exploited. A typical sensor unit according to this concept includes multiple MEMS sensors and sensor-readout circuitry fabricated together on a single chip and packaged compactly with a microprocessor that performs several functions, including execution of the MSA algorithm. In the MSA algorithm, the readings from all the sensors in an array at a given instant of time are compared and the reliability of each sensor is quantified. This comparison of readings and quantification of reliabilities involves the calculation of the ratio between every sensor reading and every other sensor reading, plus calculation of the sum of all such ratios. Then one output reading for the given instant of time is computed as a weighted average of the readings of all the sensors. In this computation, the weight for each sensor is the aforementioned value used to quantify its reliability. In an optional variant of the MSA algorithm that can be implemented easily, a running sum of the reliability value for each sensor at previous time steps as well as at the present time step is used as the weight of the sensor in calculating the weighted average at the present time step. In this variant, the weight of a sensor that continually fails gradually decreases, so that eventually, its influence over the output reading becomes minimal: In effect, the sensor system "learns" which sensors to trust and which not to trust. The MSA algorithm incorporates a criterion for deciding whether there remain enough sensor readings that approximate each other sufficiently closely to constitute a majority for the purpose of quantifying reliability. This criterion is, simply, that if there do not exist at least three sensors having weights greater than a prescribed minimum acceptable value, then the array as a whole is deemed to have failed.

Immer, Christopher↗
NASA NTRS1996

Software Reliability Issues Concerning Large and Safety Critical Software Systems

This research was undertaken to provide NASA with a survey of state-of-the-art techniques using in industrial and academia to provide safe, reliable, and maintainable software to drive large systems. Such systems must match the complexity and strict safety requirements of NASA's shuttle system. In particular, the Launch Processing System (LPS) is being considered for replacement. The LPS is responsible for monitoring and commanding the shuttle during test, repair, and launch phases. NASA built this system in the 1970's using mostly hardware techniques to provide for increased reliability, but it did so often using custom-built equipment, which has not been able to keep up with current technologies. This report surveys the major techniques used in industry and academia to ensure reliability in large and critical computer systems.

Kamel, Khaled↗
NASA NTRS1995

A highly reliable, high performance open avionics architecture for real time Nap-of-the-Earth operations

An Army Fault Tolerant Architecture (AFTA) has been developed to meet real-time fault tolerant processing requirements of future Army applications. AFTA is the enabling technology that will allow the Army to configure existing processors and other hardware to provide high throughput and ultrahigh reliability necessary for TF/TA/NOE flight control and other advanced Army applications. A comprehensive conceptual study of AFTA has been completed that addresses a wide range of issues including requirements, architecture, hardware, software, testability, producibility, analytical models, validation and verification, common mode faults, VHDL, and a fault tolerant data bus. A Brassboard AFTA for demonstration and validation has been fabricated, and two operating systems and a flight-critical Army application have been ported to it. Detailed performance measurements have been made of fault tolerance and operating system overheads while AFTA was executing the flight application in the presence of faults.

Harper, Richard E.↗
NASA NTRS1989

First incremental buy for Increment 2 of the Space Transportation System (STS)

Thiokol manufactured and delivered 9 flight motors to KSC on schedule. All test flights were successful. All spent SRMs were recovered. Design, development, manufacture, and delivery of required transportation, handling, and checkout equipment to MSFC and to KSC were completed on schedule. All items of data required by DPD 400 were prepared and delivered as directed. In the system requirements and analysis area, the point of departure from Buy 1 to the operational phase was developed in significant detail with a complete set of transition documentation available. The documentation prepared during the Buy 1 program was maintained and updated where required. The following flight support activities should be continued through other production programs: as-built materials usage tracking on all flight hardware; mass properties reporting for all flight hardware until sample size is large enough to verify that the weight limit requirements were met; ballistic predictions and postflight performance assessments for all production flights; and recovered SRM hardware inspection and anomaly identification. In the safety, reliability, and quality assurance area, activities accomplished were assurance oriented in nature and specifically formulated to prevent problems and hardware failures. The flight program to date has adequately demonstrated the success of this assurance approach. The attention focused on details of design, analysis, manufacture, and inspection to assure the production of high-quality hardware has resulted in the absence of flight failures. The few anomalies which did occur were evaluated, design or manufacturing changes incorporated, and corrective actions taken to preclude recurrence.

Source record↗
NASA NTRS1981

Reliability achievement in high technology space systems

The production of failure-free hardware is discussed. The elements required to achieve such hardware are: technical expertise to design, analyze, and fully understand the design; use of high reliability parts and materials control in the manufacturing process; and testing to understand the system and weed out defects. The durability of the Hughes family of satellites is highlighted.

Lindstrom, D. L.↗
NASA NTRS1962

RENDEZVOUS AND DOCKING TECHNIQUES

To implement the primary space mission of this decade – manned lunar exploration -- the operational assistance of rendezvous and docking is being considered as an alternative to possible problems in obtaining a boost vehicle capable of direct flight. This paper concentrates on the mechanization of the rendezvous and docking phase of such a lunar mission. As indicated in previous papers, rendezvous can take place in either an earth or lunar orbit (or on the lunar surface); it can involve the mating of stages, transfer of fuel, or the return of a shuttle to a “mother” ship; direct ascent or parking orbits can be used; the orbits can be circular or more general ellipses; finally, either or both of the spacecraft can participate in the rendezvous maneuvers. Since there is no intent here to discuss the pros and cons of each approach or to cover all possible mission profiles, guidance schemes and hardware configurations, one particular profile has been selected to display the significant features of most rendezvous missions. In many respects, rendezvous is less difficult than aircraft interception since the target is friendly and there is no severe time constraint. The latter feature allows considerable freedom of design especially with the great versatility of a human in the loop. This remains true even for a purely automatic mode. Perhaps the largest design problem concerns the selection of the mission to be implemented followed by the optimization or systems engineering of a mechanization from the multitude of possible schemes and techniques. A most important factor in the optimization is that of reliability and the redundancy, alternate or backup modes, etc., associated with the approach. While a primary system can be rather easily mechanized with modest equipment requirements, reliability considerations will result in additional hardware, tighter specifications and more safety factors (e. g., propellant margin). This is a very complex area and will only briefly be mentioned in the following discussion.

Rendezvous↗
NASA NTRS2006

Ultra reliability at NASA

Ultra reliable systems are critical to NASA particularly as consideration is being given to extended lunar missions and manned missions to Mars. NASA has formulated a program designed to improve the reliability of NASA systems. The long term goal for the NASA ultra reliability is to ultimately improve NASA systems by an order of magnitude. The approach outlined in this presentation involves the steps used in developing a strategic plan to achieve the long term objective of ultra reliability. Consideration is given to: complex systems, hardware (including aircraft, aerospace craft and launch vehicles), software, human interactions, long life missions, infrastructure development, and cross cutting technologies. Several NASA-wide workshops have been held, identifying issues for reliability improvement and providing mitigation strategies for these issues. In addition to representation from all of the NASA centers, experts from government (NASA and non-NASA), universities and industry participated. Highlights of a strategic plan, which is being developed using the results from these workshops, will be presented.

risk↗
NASA NTRS1996

Method of Testing and Predicting Failures of Electronic Mechanical Systems

A method employing a knowledge base of human expertise comprising a reliability model analysis implemented for diagnostic routines is disclosed. The reliability analysis comprises digraph models that determine target events created by hardware failures human actions, and other factors affecting the system operation. The reliability analysis contains a wealth of human expertise information that is used to build automatic diagnostic routines and which provides a knowledge base that can be used to solve other artificial intelligence problems.

Iverson, David L.↗
NASA NTRS2019

Integration of analyses in an EMC control plan for avionics hardware in space applications

An EMC Control Plan is a very valuable tool for outlining the processes needed to suppress EMI and provide EMC for the avionics hardware used in space applications. The EMC Control Plan provides guidance to EMC engineers and avionics hardware designers on methods, procedures, and practices to achieve optimum EMC. The design of an EMC Control Plan for space avionics requires unique challenges due to the nature of the space missions and the space environment. An EMC Control Plan for avionics hardware in space applications can be optimized by the integration of reliability and margin analyses that are uniquely suitable to space applications and avionics hardware. The paper provides a description of the analyses and the rationale for the inclusion of such analyses in the EMC Control Plan, including some examples. The paper concludes by providing a detailed outlined of an EMC Control Plan for avionics hardware in space applications and how this approach fits well with the overall avionics hardware design and development cycle.

Perez, Reinaldo↗
NASA NTRS1983

Packet telemetry and packet telecommand - The new generation of spacecraft data handling techniques

Because of rising costs and reduced reliability of spacecraft and ground network hardware and software customization, standardization Packet Telemetry and Packet Telecommand concepts are emerging as viable alternatives. Autonomous packets of data, within each concept, which are created within ground and space application processes through the use of formatting techniques, are switched end-to-end through the space data network to their destination application processes through the use of standard transfer protocols. This process may result in facilitating a high degree of automation and interoperability because of completely mission-independent-designed intermediate data networks. The adoption of an international guideline for future space telemetry formatting of the Packet Telemetry concept, and the advancement of the NASA-ESA Working Group's Packet Telecommand concept to a level of maturity parallel to the of Packet Telemetry are the goals of the Consultative Committee for Space Data Systems. Both the Packet Telemetry and Packet Telecommand concepts are reviewed.

Hooke, A. J.↗
NASA NTRS1990

Study on fault-tolerant processors for advanced launch system

Issues related to the reliability of a redundant system with large main memory are addressed. The Fault-Tolerant Processor (FTP) for the Advanced Launch System (ALS) is used as a basis for the presentation. When the system is free of latent faults, the probability of system crash due to multiple channel faults is shown to be insignificant even when voting on the outputs of computing channels is infrequent. Using channel error maskers (CEMs) is shown to improve reliability more effectively than increasing redundancy or the number of channels for applications with long mission times. Even without using a voter, most memory errors can be immediately corrected by those CEMs implemented with conventional coding techniques. In addition to their ability to enhance system reliability, CEMs (with a very low hardware overhead) can be used to dramatically reduce not only the need of memory realignment, but also the time required to realign channel memories in case, albeit rare, such a need arises. Using CEMs, two different schemes were developed to solve the memory realignment problem. In both schemes, most errors are corrected by CEMs, and the remaining errors are masked by a voter.

Shin, Kang G.↗
NASA NTRS1990

Advanced Information Processing System (AIPS)-based fault tolerant avionics architecture for launch vehicles

An avionics architecture for the advanced launch system (ALS) that uses validated hardware and software building blocks developed under the advanced information processing system program is presented. The AIPS for ALS architecture defined is preliminary, and reliability requirements can be met by the AIPS hardware and software building blocks that are built using the state-of-the-art technology available in the 1992-93 time frame. The level of detail in the architecture definition reflects the level of detail available in the ALS requirements. As the avionics requirements are refined, the architecture can also be refined and defined in greater detail with the help of analysis and simulation tools. A useful methodology is demonstrated for investigating the impact of the avionics suite to the recurring cost of the ALS. It is shown that allowing the vehicle to launch with selected detected failures can potentially reduce the recurring launch costs. A comparative analysis shows that validated fault-tolerant avionics built out of Class B parts can result in lower life-cycle-cost in comparison to simplex avionics built out of Class S parts or other redundant architectures.

Lala, Jaynarayan H.↗
NASA NTRS1990

Reliable VLSI sequential controllers

A VLSI architecture for synchronous sequential controllers is presented that has attractive qualities for producing reliable circuits. In these circuits, one hardware implementation can realize any flow table with a maximum of 2(exp n) internal states and m inputs. Also all design equations are identical. A real time fault detection means is presented along with a strategy for verifying the correctness of the checking hardware. This self check feature can be employed with no increase in hardware. The architecture can be modified to achieve fail safe designs. With no increase in hardware, an adaptable circuit can be realized that allows replacement of faulty transitions with fault free transitions.

Whitaker, S.↗