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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 1,531 records · Page 85
All sourcesNASA NTRSDOE OSTI
NASA NTRS1993

Development of a case tool to support decision based software development

A summary of the accomplishments of the research over the past year are presented. Achievements include: made demonstrations with DHC, a prototype supporting decision based software development (DBSD) methodology, for Paramax personnel at ODU; met with Paramax personnel to discuss DBSD issues, the process of integrating DBSD and Refinery and the porting process model; completed and submitted a paper describing DBSD paradigm to IFIP '92; completed and presented a paper describing the approach for software reuse at the Software Reuse Workshop in April 1993; continued to extend DHC with a project agenda, facility necessary for a better project management; completed a primary draft of the re-engineering process model for porting; created a logging form to trace all the activities involved in the process of solving the reengineering problem, and developed a primary chart with the problems involved by the reengineering process.

Wild, Christian J.↗
NASA NTRS1991

ControlShell - A real-time software framework

ControlShell is designed to enable modular design and impplementation of real-time software. It is an object-oriented tool-set for real-time software system programming. It provides a series of execution and data interchange mechansims that form a framework for building real-time applications. These mechanisms allow a component-based approach to real-time software generation and mangement. By defining a set of interface specifications for intermodule interaction, ControlShell provides a common platform that is the basis for real-time code development and exchange.

Schneider, Stanley A.↗
NASA NTRS1991

On the use and the performance of software reliability growth models

We address the problem of predicting future failures for a piece of software. The number of failures occurring during a finite future time interval is predicted from the number failures observed during an initial period of usage by using software reliability growth models. Two different methods for using the models are considered: straightforward use of individual models, and dynamic selection among models based on goodness-of-fit and quality-of-prediction criteria. Performance is judged by the relative error of the predicted number of failures over future finite time intervals relative to the number of failures eventually observed during the intervals. Six of the former models and eight of the latter are evaluated, based on their performance on twenty data sets. Many open questions remain regarding the use and the performance of software reliability growth models.

Keiller, Peter A.↗
NASA NTRS1994

Maximizing Performance Of A Telerobot With Minimal Software

Control software system of seven-degree-of-freedom telerobot designed to elicit maximum performance from minimal, fixed-software computer at remote robot site. Includes multiple control modules, each providing parameter-driven control of specified aspect of behavior of telerobot. Software system runs in Ada language on multiple 68020 processors or potentially on single central processing unit. Conceived for use in outer space, also proves useful in underwater construction and inspection, handling of materials in nuclear facilities, and cleaning up hazardous materials.

Backes, Paul G.↗
NASA NTRS1994

Program Helps Design Tests Of Developmental Software

Computer program called "A Formal Test Representation Language and Tool for Functional Test Designs" (TRL) provides automatic software tool and formal language used to implement category-partition method and produce specification of test cases in testing phase of development of software. Category-partition method useful in defining input, outputs, and purpose of test-design phase of development and combines benefits of choosing normal cases having error-exposing properties. Traceability maintained quite easily by creating test design for each objective in test plan. Effort to transform test cases into procedures simplified by use of automatic software tool to create cases based on test design. Method enables rapid elimination of undesired test cases from consideration and facilitates review of test designs by peer groups. Written in C language.

Hops, Jonathan↗
NASA NTRS1990

Software support environment design knowledge capture

The objective of this task is to assess the potential for using the software support environment (SSE) workstations and associated software for design knowledge capture (DKC) tasks. This assessment will include the identification of required capabilities for DKC and hardware/software modifications needed to support DKC. Several approaches to achieving this objective are discussed and interim results are provided: (1) research into the problem of knowledge engineering in a traditional computer-aided software engineering (CASE) environment, like the SSE; (2) research into the problem of applying SSE CASE tools to develop knowledge based systems; and (3) direct utilization of SSE workstations to support a DKC activity.

Dollman, Tom↗
NASA NTRS1992

Software for the derivation of scaled surface reflectances from AVIRIS data

An operational software program is now available for deriving 'scaled surface reflectances' from spectral data collected by the Airborne Visible/Infrared Imaging Spectrometer (AVIRIS). The program simulates both the atmospheric scattering and absorption effects. Brief descriptions of the algorithm, inputs, outputs, the limitations of the software, and procedures for obtaining the software are given.

Gao, Bo-Cai↗
NASA NTRS1992

Radar Analysis and Visualization Environment (RAVEN): Software for polarimetric radar analysis

Imaging radar data provides information about the geometric and dielectric properties of the Earth's surface. The Jet Propulsion Laboratory (JPL) polarimetric Airborne Synthetic Aperture Radar (AIRSAR) is currently obtaining imaging radar data for use in geologic, vegetation, snow and ice, and ocean studies. In the near future, the Shuttle Imaging Radar C (SIR-C/X-SAR) and the Earth Observing System Synthetic Aperture Radar (EOS SAR) will also collect polarimetric radar data. A need exists for a user-friendly, interactive software package for analysis of these polarimetric radar data sets. Previous software packages, such as JPL's Multiview, while providing some analysis capabilities for these data, did not allow interactive viewing and were tied to specific image display hardware with operating system dependencies. A prototype software system, the 'Radar Analysis and Visualization Environment' (RAVEN) under development at the Center for the Study of Earth from Space (CSES) at the University of Colorado, is designed to deal with data from the JPL AIRSAR instrument and other proposed polarimetric radar instruments. RAVEN is being developed using the Interactive Data Language (IDL). It takes advantage of high speed disk access and fast processors running under the UNIX operating system in an X-windows environment to allow for rapid, interactive visualization of AIRSAR data in both image and graphical ways. It provides a user-friendly interface through the use of menus, sliders, buttons, and display windows.

Kierein-Young, K. S.↗
NASA NTRS1992

Automatic AVHRR image navigation software

This is the final report describing the work done on the project entitled Automatic AVHRR Image Navigation Software funded through NASA-Washington, award NAGW-3224, Account 153-7529. At the onset of this project, we had developed image navigation software capable of producing geo-registered images from AVHRR data. The registrations were highly accurate but required a priori knowledge of the spacecraft's axes alignment deviations, commonly known as attitude. The three angles needed to describe the attitude are called roll, pitch, and yaw, and are the components of the deviations in the along scan, along track and about center directions. The inclusion of the attitude corrections in the navigation software results in highly accurate georegistrations, however, the computation of the angles is very tedious and involves human interpretation for several steps. The technique also requires easily identifiable ground features which may not be available due to cloud cover or for ocean data. The current project was motivated by the need for a navigation system which was automatic and did not require human intervention or ground control points. The first step in creating such a system must be the ability to parameterize the spacecraft's attitude. The immediate goal of this project was to study the attitude fluctuations and determine if they displayed any systematic behavior which could be modeled or parameterized. We chose a period in 1991-1992 to study the attitude of the NOAA 11 spacecraft using data from the Tiros receiving station at the Colorado Center for Astrodynamic Research (CCAR) at the University of Colorado.

Baldwin, Dan↗
NASA NTRS1992

MOSAIC: Software for creating mosaics from collections of images

We have developed a powerful, versatile image processing and analysis software package called MOSAIC, designed specifically for the manipulation of digital astronomical image data obtained with (but not limited to) two-dimensional array detectors. The software package is implemented using the Interactive Data Language (IDL), and incorporates new methods for processing, calibration, analysis, and visualization of astronomical image data, stressing effective methods for the creation of mosaic images from collections of individual exposures, while at the same time preserving the photometric integrity of the original data. Since IDL is available on many computers, the MOSAIC software runs on most UNIX and VAX workstations with the X-Windows or Sun View graphics interface.

Varosi, F.↗
NASA NTRS1993

Cost benefits of advanced software: A review of methodology used at Kennedy Space Center

To assist rational investments in advanced software, a formal, explicit, and multi-perspective cost-benefit analysis methodology is proposed. The methodology can be implemented through a six-stage process which is described and explained. The current practice of cost-benefit analysis at KSC is reviewed in the light of this methodology. The review finds that there is a vicious circle operating. Unsound methods lead to unreliable cost-benefit estimates. Unreliable estimates convince management that cost-benefit studies should not be taken seriously. Then, given external demands for cost-benefit estimates, management encourages software enginees to somehow come up with the numbers for their projects. Lacking the expertise needed to do a proper study, courageous software engineers with vested interests use ad hoc and unsound methods to generate some estimates. In turn, these estimates are unreliable, and the cycle continues. The proposed methodology should help KSC to break out of this cycle.

Joglekar, Prafulla N.↗
NASA NTRS1993

The mission events graphic generator software: A small tool with big results

Utilization of graphics has long been a useful methodology for many aspects of spacecraft operations. A personal computer based software tool that implements straight-forward graphics and greatly enhances spacecraft operations is presented. This unique software tool is the Mission Events Graphic Generator (MEGG) software which is used in support of the Hubble Space Telescope (HST) Project. MEGG reads the HST mission schedule and generates a graphical timeline.

Lupisella, Mark↗
NASA NTRS1993

Software reuse in spacecraft planning and scheduling systems

The use of a software toolkit and development methodology that supports software reuse is described. The toolkit includes source-code-level library modules and stand-alone tools which support such tasks as data reformatting and report generation, simple relational database applications, user interfaces, tactical planning, strategic planning and documentation. The current toolkit is written in C and supports applications that run on IBM-PC's under DOS and UNlX-based workstations under OpenLook and Motif. The toolkit is fully integrated for building scheduling systems that reuse AI knowledge base technology. A typical scheduling scenario and three examples of applications that utilize the reuse toolkit will be briefly described. In addition to the tools themselves, a description of the software evolution and reuse methodology that was used is presented.

Mclean, David↗
NASA NTRS1993

Evaluation of the efficiency and fault density of software generated by code generators

Flight computers and flight software are used for GN&C (guidance, navigation, and control), engine controllers, and avionics during missions. The software development requires the generation of a considerable amount of code. The engineers who generate the code make mistakes and the generation of a large body of code with high reliability requires considerable time. Computer-aided software engineering (CASE) tools are available which generates code automatically with inputs through graphical interfaces. These tools are referred to as code generators. In theory, code generators could write highly reliable code quickly and inexpensively. The various code generators offer different levels of reliability checking. Some check only the finished product while some allow checking of individual modules and combined sets of modules as well. Considering NASA's requirement for reliability, an in house manually generated code is needed. Furthermore, automatically generated code is reputed to be as efficient as the best manually generated code when executed. In house verification is warranted.

Schreur, Barbara↗
NASA NTRS1993

Technology drivers for flight telerobotic system software

Viewgraphs on technology drivers for flight telerobotic system software are included. Topics covered include: flight software lines of code; flight computer architecture; system safety; safety critical parameters; system safety - software functions.

Labaugh, Robert↗
NASA NTRS1993

Developing interpretable models with optimized set reduction for identifying high risk software components

Applying equal testing and verification effort to all parts of a software system is not very efficient, especially when resources are limited and scheduling is tight. Therefore, one needs to be able to differentiate low/high fault frequency components so that testing/verification effort can be concentrated where needed. Such a strategy is expected to detect more faults and thus improve the resulting reliability of the overall system. This paper presents the Optimized Set Reduction approach for constructing such models, intended to fulfill specific software engineering needs. Our approach to classification is to measure the software system and build multivariate stochastic models for predicting high risk system components. We present experimental results obtained by classifying Ada components into two classes: is or is not likely to generate faults during system and acceptance test. Also, we evaluate the accuracy of the model and the insights it provides into the error making process.

Briand, Lionel C.↗
NASA NTRS1993

Using certification trails to achieve software fault tolerance

A conceptually novel and powerful technique to achieve fault tolerance in hardware and software systems is introduced. When used for software fault tolerance, this new technique uses time and software redundancy and can be outlined as follows. In the initial phase, a program is run to solve a problem and store the result. In addition, this program leaves behind a trail of data called a certification trail. In the second phase, another program is run which solves the original problem again. This program, however, has access to the certification trail left by the first program. Because of the availability of the certification trail, the second phase can be performed by a less complex program and can execute more quickly. In the final phase, the two results are accepted as correct; otherwise an error is indicated. An essential aspect of this approach is that the second program must always generate either an error indication or a correct output even when the certification trail it receives from the first program is incorrect. The certification trail approach to fault tolerance was formalized and it was illustrated by applying it to the fundamental problem of finding a minimum spanning tree. Cases in which the second phase can be run concorrectly with the first and act as a monitor are discussed. The certification trail approach was compared to other approaches to fault tolerance. Because of space limitations we have omitted examples of our technique applied to the Huffman tree, and convex hull problems. These can be found in the full version of this paper.

Sullivan, Gregory F.↗
NASA NTRS1993

Lessons learned applying CASE methods/tools to Ada software development projects

This paper describes the lessons learned from introducing CASE methods/tools into organizations and applying them to actual Ada software development projects. This paper will be useful to any organization planning to introduce a software engineering environment (SEE) or evolving an existing one. It contains management level lessons learned, as well as lessons learned in using specific SEE tools/methods. The experiences presented are from Alpha Test projects established under the STARS (Software Technology for Adaptable and Reliable Systems) project. They reflect the front end efforts by those projects to understand the tools/methods, initial experiences in their introduction and use, and later experiences in the use of specific tools/methods and the introduction of new ones.

Blumberg, Maurice H.↗