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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 379 records · Page 21
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Automatic documentation system extension to multi-manufacturers' computers and to measure, improve, and predict software reliability

The DOMONIC system has been modified to run on the Univac 1108 and the CDC 6600 as well as the IBM 370 computer system. The DOMONIC monitor system has been implemented to gather data which can be used to optimize the DOMONIC system and to predict the reliability of software developed using DOMONIC. The areas of quality metrics, error characterization, program complexity, program testing, validation and verification are analyzed. A software reliability model for estimating program completion levels and one on which to base system acceptance have been developed. The DAVE system which performs flow analysis and error detection has been converted from the University of Colorado CDC 6400/6600 computer to the IBM 360/370 computer system for use with the DOMONIC system.

Simmons, D. B.↗
NASA NTRS1993

Advanced Information Processing System (AIPS)

Advanced Information Processing System (AIPS) is a computer systems philosophy, a set of validated hardware building blocks, and a set of validated services as embodied in system software. The goal of AIPS is to provide the knowledgebase which will allow achievement of validated fault-tolerant distributed computer system architectures, suitable for a broad range of applications, having failure probability requirements of 10E-9 at 10 hours. A background and description is given followed by program accomplishments, the current focus, applications, technology transfer, FY92 accomplishments, and funding.

Pitts, Felix L.↗
NASA NTRS1983

Metric analysis and data validation across FORTRAN projects

The desire to predict the effort in developing or explaining the quality of software has led to the proposal of several metrics. As a step toward validating these metrics, the Software Engineering Laboratory (SEL) has analyzed the software science metrics, cyclomatic complexity, and various standard program measures for their relation to effort (including design through acceptance testing), development errors (both discrete and weighted according to the amount of time to locate and fix), and one another. The data investigated are collected from a project FORTRAN environment and examined across several projects at once, within individual projects and by reporting accuracy checks demonstrating the need to validate a database. When the data comes from individual programmers or certain validated projects, the metrics' correlations with actual effort seem to be strongest. For modules developed entirely by individual programmers, the validity ratios induce a statistically significant ordering of several of the metrics' correlations. When comparing the strongest correlations, neither software science's E metric cyclomatic complexity not source lines of code appears to relate convincingly better with effort than the others.

Basili, Victor R.↗
NASA NTRS2005

Validation of the Atmospheric Infrared Sounder (AIRS) over the Antarctic Plateau: Low Radiance, Low Humidity, and Thin Clouds

The main goal of the project has been to use specialized measurements collected at the Antarctic Plateau to provide validation of the Atmospheric InfraRed Sounder (AIRS) spectral radiances and some AIRS Level 2 products. As proposed, efforts conducted at the University of Wisconsin are focused on providing technical information, data, and software in support of the validation studies.

Tobin, David C.↗
NASA NTRS1995

Adaptive Optimization of Aircraft Engine Performance Using Neural Networks

Preliminary results are presented on the development of an adaptive neural network based control algorithm to enhance aircraft engine performance. This work builds upon a previous National Aeronautics and Space Administration (NASA) effort known as Performance Seeking Control (PSC). PSC is an adaptive control algorithm which contains a model of the aircraft's propulsion system which is updated on-line to match the operation of the aircraft's actual propulsion system. Information from the on-line model is used to adapt the control system during flight to allow optimal operation of the aircraft's propulsion system (inlet, engine, and nozzle) to improve aircraft engine performance without compromising reliability or operability. Performance Seeking Control has been shown to yield reductions in fuel flow, increases in thrust, and reductions in engine fan turbine inlet temperature. The neural network based adaptive control, like PSC, will contain a model of the propulsion system which will be used to calculate optimal control commands on-line. Hopes are that it will be able to provide some additional benefits above and beyond those of PSC. The PSC algorithm is computationally intensive, it is valid only at near steady-state flight conditions, and it has no way to adapt or learn on-line. These issues are being addressed in the development of the optimal neural controller. Specialized neural network processing hardware is being developed to run the software, the algorithm will be valid at steady-state and transient conditions, and will take advantage of the on-line learning capability of neural networks. Future plans include testing the neural network software and hardware prototype against an aircraft engine simulation. In this paper, the proposed neural network software and hardware is described and preliminary neural network training results are presented.

Simon, Donald L.↗
NASA NTRS2006

Database of Properties of Meteors

A database of properties of meteors, and software that provides access to the database, are being developed as a contribution to continuing efforts to model the characteristics of meteors with increasing accuracy. Such modeling is necessary for evaluation of the risk of penetration of spacecraft by meteors. For each meteor in the database, the record will include an identification, date and time, radiant properties, ballistic coefficient, radar cross section, size, density, and orbital elements. The property of primary interest in the present case is density, and one of the primary goals in this case is to derive densities of meteors from their atmospheric decelerations. The database and software are expected to be valid anywhere in the solar system. The database will incorporate new data plus results of meteoroid analyses that, heretofore, have not been readily available to the aerospace community. Taken together, the database and software constitute a model that is expected to provide improved estimates of densities and to result in improved risk analyses for interplanetary spacecraft. It is planned to distribute the database and software on a compact disk.

Suggs, Rob↗
DOE OSTI2025

Implementation of tritium transport in a gas-liquid contactor CFD simulation of tritium extraction from lead-lithium in ANSYS fluent

Modifications to the Computational Fluid Dynamic (CFD) software ANSYS Fluent were done to quantify and characterize tritium transport in Gas-Liquid Contactors (GLCs). A double-slit, Ergun-like equation was employed for the porous media model, with Ergun coefficients validated with Sulzer’s Sulcol software. Tritium transport from PbLi within the GLC was verified against analytical models. The geometry of the CFD model was based on the MELODIE GLC experiment. The hydrodynamic CFD pressure drop results align well with SulCol estimations and fall between the predictions of the analytical Delft-Olujic and Billet & Schultes models. In terms of mass transfer efficiency, traditional mass transfer models showed a significant deviation from experimental results when using varying values of H solubility in PbLi. A saturation phenomenon occurred when utilizing high solubility values for hydrogen in PbLi. In conclusion, a modified film theory mass transfer coefficient, incorporating either the Delft-Olujic or Billet & Schultes wettability model, yielded CFD-predicted extraction efficiencies that closely matched experimental measurements.

70 - PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS2011

Updates on HRF Payloads Operations in Columbus ATCS

The NASA developed Human Research Facility 1 (HRF1) and Human Research Facility (HRF2) experiment racks have been operating in the European Space Agency (ESA) Columbus module of the International Space Station (ISS) since Summer 2008. The two racks are of the same design. Since the start of operations, unexpected pressure spikes were observed in the Columbus module's thermal-hydraulic system during the racks activation sequence. The root cause of these spikes was identified in the activation command sequence in the Rack Interface Controller (RIC), which controls the flow of thermal-hydraulic system fluid through the rack. A new Common RIC Software (CRS) release fixed the bug and was uploaded on both racks in late 2009. This paper gives a short introduction to the topic, describes the Columbus module countermeasures to mitigate the spikes, describes the ground validation test of the new software, and describes the flight checks performed before and after the final upload. Finally, the new on-orbit test designed to further simplify the racks hydraulic management is presented.

DePalo, Savino↗
DOE OSTI2025

Transition of SRT Source Term Software to Modern Version Control System to Enable More Efficient Verification, Validation, and User Engagement

The Simplified Radionuclide Transport (SRT) code assists in reactor design and licensing by providing a detailed analysis of radionuclide transport under specific transient scenarios. This analysis is essential for ensuring that reactors meet safety and regulatory standards before they are authorized to operate. Mechanistic source term analysis, which involves a realistic evaluation of radionuclide behavior from the source to the environment, is a key component of this process. It provides a comprehensive understanding of potential release scenarios, supporting the development of robust safety measures.

22 GENERAL STUDIES OF NUCLEAR REACTORS↗
DOE OSTI2026

A Scalable Test-Bed for Direct Current Current Transformer Automated Functional Testing and Characterization

This article describes a scalable test-bed for automation of measurements of the direct current current transformers (DCCT). Automation of measurement involves functional measurements, fault event based measurements and data validation. The test-bed is designed to measure up to 20 DCCTs at a time with software based measurement repetition checks and validation of the measurements.

43 PARTICLE ACCELERATORS↗
NASA NTRS1986

An empirical study of software design practices

Software engineers have developed a large body of software design theory and folklore, much of which was never validated. The results of an empirical study of software design practices in one specific environment are presented. The practices examined affect module size, module strength, data coupling, descendant span, unreferenced variables, and software reuse. Measures characteristic of these practices were extracted from 887 FORTRAN modules developed for five flight dynamics software projects monitored by the Software Engineering Laboratory (SEL). The relationship of these measures to cost and fault rate was analyzed using a contingency table procedure. The results show that some recommended design practices, despite their intuitive appeal, are ineffective in this environment, whereas others are very effective.

Card, David N.↗
NASA NTRS1998

Real-Time Sensor Validation System Developed

Real-time sensor validation improves process monitoring and control system dependability by ensuring data integrity through automated detection of sensor data failures. The NASA Lewis Research Center, Expert Microsystems, and Intelligent Software Associates have developed an innovative sensor validation system that can automatically detect automated sensor failures in real-time for all types of mission-critical systems. This system consists of a sensor validation network development system and a real-time kernel. The network development system provides tools that enable systems engineers to automatically generate software that can be embedded within an application. The sensor validation methodology captured by these tools can be scaled to validate any number of sensors, and permits users to specify system sensitivity. The resulting software reliably detects all types of sensor data failures.

Zakrajsek, June F.↗
NASA NTRS2010

Importance of Requirements Analysis & Traceability to Improve Software Quality and Reduce Cost and Risk

The goal of this paper is to emphasize the importance of developing complete and unambiguous requirements early in the project cycle (prior to Preliminary Design Phase). Having a complete set of requirements early in the project cycle allows sufficient time to generate a traceability matrix. Requirements traceability and analysis are the key elements in improving verification and validation process, and thus overall software quality. Traceability can be most beneficial when the system changes. If changes are made to high-level requirements it implies that low-level requirements need to be modified. Traceability ensures that requirements are appropriately and efficiently verified at various levels whereas analysis ensures that a rightly interpreted set of requirements is produced.

Kapoor, Manju M.↗
NASA NTRS1982

DSN data systems software methodology

A software methodology for JPL deep space network (DSN) data systems software implementations through transfer and delivery is presented. The DSN Data Systems Software Methodology is compatible with and depends on DSN software methodology and also incorporates the characteristics of real-time program development in a DSN environment. The DSN Data Systems software implementation consists of a series of six distinct phases. An Independent Group is responsible for verification and validation of the DSN Data Systems software during developing phases. The DSN data systems software methodology is applied to all development software provided for or by the DSN data systems section in Mark IV where there is a desire for reliability, maintainability, and usability within budget and schedule constraints.

Hung, C. K.↗
NASA NTRS1987

SAGA: A project to automate the management of software production systems

The Software Automation, Generation and Administration (SAGA) project is investigating the design and construction of practical software engineering environments for developing and maintaining aerospace systems and applications software. The research includes the practical organization of the software lifecycle, configuration management, software requirements specifications, executable specifications, design methodologies, programming, verification, validation and testing, version control, maintenance, the reuse of software, software libraries, documentation, and automated management.

Campbell, Roy H.↗
NASA NTRS1996

Modeling the Object-Oriented Space Through Validated Measures

In order to truly understand software and the software development process, software measurement must be better understood. A beginning step toward a better understanding of software measurement is the categorization of the measurements by some meaningful taxonomy. The most meaningful taxonomy would capture the basic nature of the subject oriented (O-O) space. The interesting characteristics of object oriented software offer a starting point for such a categorization of measures. A taxonomy has been developed based on fourteen characteristics of object-oriented software gathered from the literature This taxonomy allows us to easily see gaps and redundancies in the O-O measures. The taxonomy also clearly differentiates among taxa so that there is no ambiguity as to the taxon to which a measure belongs. The taxonomy has been populated with thirty-two measures that have been validated in the narrow sense of Fenton, using measurement theory with Zuse's augmentation.

Neal, Ralph D.↗
NASA NTRS2019

Agile Approach to Assuring the Safety-Critical Embedded Software for NASA's Orion Spacecraft

Human-rated missions like NASA's Exploration Mission - 1 (EM-1) and the Orion Multi-Purpose Crew Vehicle are becoming exceedingly complex in terms of software's contribution to achieving mission objectives. The increasing complexity and inherent safety critical nature of the embedded flight software imposes a unique resource challenge to assurance providers responsible for affirming that the mission is going to fly safely. Another challenge NASA and other Government agencies are facing is that more and more software is being developed using an agile development methodology, which is divergent from the typical waterfall, iterative, and incremental development methodologies assurance providers generally observe in the development of safety-critical embedded software. Orion Independent Verification and Validation (IV&V) has addressed these challenges by providing focused assurance results of critical mission capabilities prioritized by a dynamic assessment of risk level. Prior to this approach, Orion IV&V evaluated areas of risk in much broader, and more static, terms. Due to the agile software development life cycle that Orion follows, IV&V findings were often reported months out of phase with the developer thereby imposing increased rework costs. As a result of evolving the approach to adding assurance on Orion, IV&V is able to incrementally deliver high-priority assurance conclusions and more impactful issues more in phase with the developer activities, thereby increasing the value of the findings to the project. The agile IV&V approach employed by the Orion IV&V team strives to achieve a cadence of delivery that matches the pace of development. This agile approach provides increased flexibility for the assurance provider to become more efficient in reporting assurance conclusions and issues. This paper and presentation will discuss the principles which drive the design of our approach, results to date, and stimulate thinking for groups looking to add assurance to software being developed using an agile methodology.

Justin Smith↗