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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 NTRS2006

Explaining Verification Conditions

The Hoare approach to program verification relies on the construction and discharge of verification conditions (VCs) but offers no support to trace, analyze, and understand the VCs themselves. We describe a systematic extension of the Hoare rules by labels so that the calculus itself can be used to build up explanations of the VCs. The labels are maintained through the different processing steps and rendered as natural language explanations. The explanations can easily be customized and can capture different aspects of the VCs; here, we focus on their structure and purpose. The approach is fully declarative and the generated explanations are based only on an analysis of the labels rather than directly on the logical meaning of the underlying VCs or their proofs. Keywords: program verification, Hoare calculus, traceability.

Deney, Ewen↗
NASA NTRS1975

General verification description

A brief general description of the ASTP flight program verification was presented. The total program verification effort assures the accuracy and adequacy of the LVDC flight program and verifies that the final program meets mission requirements and conforms to program documentation. The flight program's functional requirements to integrate the guidance and control system with the launch vehicle sequencing system are verified directly by analysis of many special logic checks designed for this purpose and indirectly by the correct overall program response to nominal and numerous perturbed conditions. Verification of the interaction of function requirements is accomplished on every case run during the verification effort.

Source record↗
NASA NTRS2002

Integrating Formal Methods and Testing 2002

Traditionally, qualitative program verification methodologies and program testing are studied in separate research communities. None of them alone is powerful and practical enough to provide sufficient confidence in ultra-high reliability assessment when used exclusively. Significant advances can be made by accounting not only tho formal verification and program testing. but also the impact of many other standard V&V techniques, in a unified software reliability assessment framework. The first year of this research resulted in the statistical framework that, given the assumptions on the success of the qualitative V&V and QA procedures, significantly reduces the amount of testing needed to confidently assess reliability at so-called high and ultra-high levels (10-4 or higher). The coming years shall address the methodologies to realistically estimate the impacts of various V&V techniques to system reliability and include the impact of operational risk to reliability assessment. Combine formal correctness verification, process and product metrics, and other standard qualitative software assurance methods with statistical testing with the aim of gaining higher confidence in software reliability assessment for high-assurance applications. B) Quantify the impact of these methods on software reliability. C) Demonstrate that accounting for the effectiveness of these methods reduces the number of tests needed to attain certain confidence level. D) Quantify and justify the reliability estimate for systems developed using various methods.

Cukic, Bojan↗
NASA NTRS2002

Options and Risk for Qualification of Electric Propulsion System

Electric propulsion vehicle systems envelop a wide range of propulsion alternatives including solar and nuclear, which present unique circumstances for qualification. This paper will address the alternatives for qualification of electric propulsion spacecraft systems. The approach taken will be to address the considerations for qualification at the various levels of systems definition. Additionally, for each level of qualification the system level risk implications will be developed. Also, the paper will explore the implications of analysis verses test for various levels of systems definition, while retaining the objectives of a verification program. The limitations of terrestrial testing will be explored along with the risk and implications of orbital demonstration testing. The paper will seek to develop a template for structuring of a verification program based on cost, risk and value return. A successful verification program should establish controls and define objectives of the verification compliance program. Finally the paper will seek to address the political and programmatic factors, which may impact options for system verification.

Bailey, Michelle↗
NASA NTRS1979

Design of a verifiable subset for HAL/S

An attempt to evaluate the applicability of program verification techniques to the existing programming language, HAL/S is discussed. HAL/S is a general purpose high level language designed to accommodate the software needs of the NASA Space Shuttle project. A diversity of features for scientific computing, concurrent and real-time programming, and error handling are discussed. The criteria by which features were evaluated for inclusion into the verifiable subset are described. Individual features of HAL/S with respect to these criteria are examined and justification for the omission of various features from the subset is provided. Conclusions drawn from the research are presented along with recommendations made for the use of HAL/S with respect to the area of program verification.

Browne, J. C.↗
NASA NTRS1970

Skylab program CSM verification analysis report

The application of the SINDA computer program for the transient thermodynamic simulation of the Apollo fuel cell/radiator system for the limit condition of the proposed Skylab mission is described. Results are included for the thermal constraints imposed upon the Pratt and Whitney fuel cell power capability by the Block 2 EPS radiator system operating under the Skylab fixed attitude orbits.

Schaefer, J. L.↗
NASA NTRS2016

JWST Telescope Integration and Test Progress

The James Webb Space Telescope (JWST) is a 6.5m, segmented, IR telescope that will explore the first light of the universe after the big bang. The JWST Optical Telescope Element (Telescope) integration and test program is well underway. The telescope was completed in the spring of 2016 and the cryogenic test equipment has been through two optical test programs leading up to the final flight verification program. The details of the telescope mirror integration will be provided along with the current status of the flight observatory. In addition, the results of the two optical ground support equipment cryo tests will be shown and how these plans fold into the flight verification program.

Matthews, Gary W.↗
NASA NTRS1987

A strategy for automatically generating programs in the lucid programming language

A strategy for automatically generating and verifying simple computer programs is described. The programs are specified by a precondition and a postcondition in predicate calculus. The programs generated are in the Lucid programming language, a high-level, data-flow language known for its attractive mathematical properties and ease of program verification. The Lucid programming is described, and the automatic program generation strategy is described and applied to several example problems.

Johnson, Sally C.↗
NASA NTRS2008

Challenges and Demands on Automated Software Revision

In the past three decades, automated program verification has undoubtedly been one of the most successful contributions of formal methods to software development. However, when verification of a program against a logical specification discovers bugs in the program, manual manipulation of the program is needed in order to repair it. Thus, in the face of existence of numerous unverified and un- certified legacy software in virtually any organization, tools that enable engineers to automatically verify and subsequently fix existing programs are highly desirable. In addition, since requirements of software systems often evolve during the software life cycle, the issue of incomplete specification has become a customary fact in many design and development teams. Thus, automated techniques that revise existing programs according to new specifications are of great assistance to designers, developers, and maintenance engineers. As a result, incorporating program synthesis techniques where an algorithm generates a program, that is correct-by-construction, seems to be a necessity. The notion of manual program repair described above turns out to be even more complex when programs are integrated with large collections of sensors and actuators in hostile physical environments in the so-called cyber-physical systems. When such systems are safety/mission- critical (e.g., in avionics systems), it is essential that the system reacts to physical events such as faults, delays, signals, attacks, etc, so that the system specification is not violated. In fact, since it is impossible to anticipate all possible such physical events at design time, it is highly desirable to have automated techniques that revise programs with respect to newly identified physical events according to the system specification.

Bonakdarpour, Borzoo↗
NASA NTRS1986

Block 2 SRM conceptual design studies. Volume 1, Book 2: Preliminary development and verification plan

Activities that will be conducted in support of the development and verification of the Block 2 Solid Rocket Motor (SRM) are described. Development includes design, fabrication, processing, and testing activities in which the results are fed back into the project. Verification includes analytical and test activities which demonstrate SRM component/subassembly/assembly capability to perform its intended function. The management organization responsible for formulating and implementing the verification program is introduced. It also identifies the controls which will monitor and track the verification program. Integral with the design and certification of the SRM are other pieces of equipment used in transportation, handling, and testing which influence the reliability and maintainability of the SRM configuration. The certification of this equipment is also discussed.

Source record↗
NASA NTRS1985

Debris control design achievements of the booster separation motors

The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented.

Smith, G. W.↗
NASA NTRS1976

The Space Shuttle's testing gauntlet

The Space Shuttle verification program is detailed, with verification network flowcharts. Performance qualification tests, life endurance tests, structural verification tests, and vibration/dynamic tests of components, subsystems, and major systems at various test levels are dealt with. Ground tests, static firings of the Shuttle main engine, external-tank separation tests, ground vibration tests of vehicle mated to external tank, and main propulsion tests and test scheduling are described. Functions of the Shuttle avionics integration laboratory and electronic systems test laboratory are discussed. Test preparations and procedures for orbital flight testing, launch pad tests, and Shuttle approach- and landing-tests are described.

Mcintosh, G. P.↗
NASA NTRS1989

SSME Alternate Turbopump Development Program: Design verification specification for high-pressure fuel turbopump

The design and verification requirements are defined which are appropriate to hardware at the detail, subassembly, component, and engine levels and to correlate these requirements to the development demonstrations which provides verification that design objectives are achieved. The high pressure fuel turbopump requirements verification matrix provides correlation between design requirements and the tests required to verify that the requirement have been met.

Source record↗
NASA NTRS2004

Lithium-Ion Verification Test Program

In order to assess the capabilities of current aerospace lithium-ion cells to perform long-term NASA missions, low-earth-orbits (LEO) testing to evaluate long-term cycle life was initiated. A flexible program was developed at NASA Glenn Research Center to enable assessment of technology developments as they occur as well as provide information about different cell vendors and cell designs. Following extensive characterization testing, cells are tested using LEO charge and discharge profiles under ten different combinations of test conditions that were statistically chosen to determine the effects of depth-of-discharge, temperature, and end-of-charge voltage on LEO cycle life. Four cells from each vendor are tested at each specific combination of conditions. Conditions included in the test matrix are depth-of-discharges of 20%, 30, 35%, and 40%; temperatures of 20, 30, and 40 C; and end-of-charge voltages of 3.85 V, 3.95 V, and 4.05 V. Cells are randomly assigned to packs and packs are randomly assigned to test conditions. The capacity of the cells to 3.0 V at the conditions of the test is being periodically measured. The results of this testing will be used to model cell performance and degradation as a function of test operating conditions. Cells are being evaluated in 4-cell series strings with charge voltage limits being applied to individual cells by charge control units designed and built at NASA Glenn Research Center. Testing is being performed at the Naval Surface Warfare Center/Crane Division in Crane, IN. Testing was initiated in September 2004 with 40 Ah cells from Saft and 30 Ah cells from Lithion. The test program is being expanded with the addition of cells from MSA and the addition of small cell modules is being considered. Preliminary results showing voltage, temperature, usable capacity per unit mass, and voltage dispersion as their changes over time for the cells at 20 C is presented.

McKissock, Barbara↗
NASA NTRS2008

Deep Impact Extended Mission Challenges for the Validation and Verification Test Program

The Deep Impact Spacecraft was launched on January 12, 2005 as part of NASA's Discovery Program as a radical mission to excavate the interior of a comet. The Spacecraft consisted of two separate entities known as the Flyby and the Impactor, which were commanded to separate prior to comet rendezvous with comet 9P/Tempel 1. The overall mission was deemed a success on July 4, 2005, as the 370-kg Impactor collided with the comet at 10.2 km/s. This event was captured using the camera and infrared spectrometer on the Flyby spacecraft, along with ground-based observatories. Since this event, the Flyby spacecraft has been in hibernation mode and has received only a small amount of maintenance. The Deep Impact Program was managed by the Jet Propulsion Laboratory (JPL), led by Dr. Michael A'Hearn from the University of Maryland in College Park, and built by Ball Aerospace & Technologies Corp. in Boulder, Colorado.

Test Bench↗
NASA NTRS1995

Introduction to Penelope

A formal program verification is a (mathematical) proof that a program executed according to its intended model meets some specification. This proves that the algorithm defined by the program is correct in the precise technical sense of being consistent with a particular specification. A program correct in this sense is free from a large and important class of errors, even though its behavior may still produce unintended results--either because the implementation of the programming language itself does not match the model of execution, or because the specification does not correctly express the user's intentions. Penelope is a prototype system for interactively developing and verifying programs that are written in a rich subset of sequential Ada. Penelope can be used to develop a program and its correctness proof incrementally, and in concert with one another. Incrementality is used in a number of ways to help make verification more tractable and more productive. For example, if an already-verified program is modified, one can attempt to prove the modified version by replaying and modifying the original verification. Penelope's specification language, Larch/Ada, belongs to the family of Larch interface languages. Larch/Ada scales up properly, in the sense that it is demonstrably sound to decompose a system hierarchically and reason locally about the implementation of each piece. Penelope has been applied in various demonstration projects--for specification (guidance control, distributed operating systems), verification (of off-the-shelf code), and formal development (by non-expert as well as expert users). Some features of Penelope have been embodied in Ada Wise, a lint-like non-interactive tool that warns of the potential for certain dynamic semantic errors in Ada programs.

Guaspari, David↗
NASA NTRS1981

Computer simulated building energy consumption for verification of energy conservation measures in network facilities

A computer program called ECPVER (Energy Consumption Program - Verification) was developed to simulate all energy loads for any number of buildings. The program computes simulated daily, monthly, and yearly energy consumption which can be compared with actual meter readings for the same time period. Such comparison can lead to validation of the model under a variety of conditions, which allows it to be used to predict future energy saving due to energy conservation measures. Predicted energy saving can then be compared with actual saving to verify the effectiveness of those energy conservation changes. This verification procedure is planned to be an important advancement in the Deep Space Network Energy Project, which seeks to reduce energy cost and consumption at all DSN Deep Space Stations.

Plankey, B.↗