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At least 955 records · Page 53
All sourcesNASA NTRSDOE OSTI
NASA NTRS1992

Developing satellite ground control software through graphical models

This paper discusses a program of investigation into software development as graphical modeling. The goal of this work is a more efficient development and maintenance process for the ground-based software that controls unmanned scientific satellites launched by NASA. The main hypothesis of the program is that modeling of the spacecraft and its subsystems, and reasoning about such models, can--and should--form the key activities of software development; by using such models as inputs, the generation of code to perform various functions (such as simulation and diagnostics of spacecraft components) can be automated. Moreover, we contend that automation can provide significant support for reasoning about the software system at the diagram level.

Bailin, Sidney↗
NASA NTRS1992

The KASE approach to domain-specific software systems

Designing software systems, like all design activities, is a knowledge-intensive task. Several studies have found that the predominant cause of failures among system designers is lack of knowledge: knowledge about the application domain, knowledge about design schemes, knowledge about design processes, etc. The goal of domain-specific software design systems is to explicitly represent knowledge relevant to a class of applications and use it to partially or completely automate various aspects of the designing systems within that domain. The hope is that this would reduce the intellectual burden on the human designers and lead to more efficient software development. In this paper, we present a domain-specific system built on top of KASE, a knowledge-assisted software engineering environment being developed at the Stanford Knowledge Systems Laboratory. We introduce the main ideas underlying the construction of domain specific systems within KASE, illustrate the application of the idea in the synthesis of a system for tracking aircraft from radar signals, and discuss some of the issues in constructing domain-specific systems.

Bhansali, Sanjay↗
NASA NTRS1992

Software design as a problem in learning theory (a research overview)

Our interest in automating software design has come out of our research in automated reasoning, inductive inference, learnability, and algebraic machine theory. We have investigated these areas extensively, in connection with specific problems of language representation, acquisition, processing, and design. In the case of formal context-free (CF) languages we established existence of finite learnable models ('behavioral realizations') and procedures for constructing them effectively. We also determined techniques for automatic construction of the models, inductively inferring them from finite examples of how they should 'behave'. These results were obtainable due to appropriate representation of domain knowledge, and constraints on the domain that the representation defined. It was when we sought to generalize our results, and adapt or apply them, that we began investigating the possibility of determining similar procedures for constructing correct software. Discussions with other researchers led us to examine testing and verification processes, as they are related to inference, and due to their considerable importance in correct software design. Motivating papers by other researchers, led us to examine these processes in some depth. Here we present our approach to those software design issues raised by other researchers, within our own theoretical context. We describe our results, relative to those of the other researchers, and conclude that they do not compare unfavorably.

Fass, Leona F.↗
NASA NTRS1993

A NASA-wide approach toward cost-effective, high-quality software through reuse

NASA Langley Research Center sponsored the second Workshop on NASA Research in Software Reuse on May 5-6, 1992 at the Research Triangle Park, North Carolina. The workshop was hosted by the Research Triangle Institute. Participants came from the three NASA centers, four NASA contractor companies, two research institutes and the Air Force's Rome Laboratory. The purpose of the workshop was to exchange information on software reuse tool development, particularly with respect to tool needs, requirements, and effectiveness. The participants presented the software reuse activities and tools being developed and used by their individual centers and programs. These programs address a wide range of reuse issues. The group also developed a mission and goals for software reuse within NASA. This publication summarizes the presentations and the issues discussed during the workshop.

Scheper, Charlotte O.↗
NASA NTRS1992

Conjunctive programming: An interactive approach to software system synthesis

This report introduces a technique of software documentation called conjunctive programming and discusses its role in the development and maintenance of software systems. The report also describes the conjoin tool, an adjunct to assist practitioners. Aimed at supporting software reuse while conforming with conventional development practices, conjunctive programming is defined as the extraction, integration, and embellishment of pertinent information obtained directly from an existing database of software artifacts, such as specifications, source code, configuration data, link-edit scripts, utility files, and other relevant information, into a product that achieves desired levels of detail, content, and production quality. Conjunctive programs typically include automatically generated tables of contents, indexes, cross references, bibliographic citations, tables, and figures (including graphics and illustrations). This report presents an example of conjunctive programming by documenting the use and implementation of the conjoin program.

Tausworthe, Robert C.↗
NASA NTRS1993

The repository-based software engineering program: Redefining AdaNET as a mainstream NASA source

The Repository-based Software Engineering Program (RBSE) is described to inform and update senior NASA managers about the program. Background and historical perspective on software reuse and RBSE for NASA managers who may not be familiar with these topics are provided. The paper draws upon and updates information from the RBSE Concept Document, baselined by NASA Headquarters, Johnson Space Center, and the University of Houston - Clear Lake in April 1992. Several of NASA's software problems and what RBSE is now doing to address those problems are described. Also, next steps to be taken to derive greater benefit from this Congressionally-mandated program are provided. The section on next steps describes the need to work closely with other NASA software quality, technology transfer, and reuse activities and focuses on goals and objectives relative to this need. RBSE's role within NASA is addressed; however, there is also the potential for systematic transfer of technology outside of NASA in later stages of the RBSE program. This technology transfer is discussed briefly.

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NASA NTRS1993

Development of a methodology for assessing the safety of embedded software systems

A Dynamic Flowgraph Methodology (DFM) based on an integrated approach to modeling and analyzing the behavior of software-driven embedded systems for assessing and verifying reliability and safety is discussed. DFM is based on an extension of the Logic Flowgraph Methodology to incorporate state transition models. System models which express the logic of the system in terms of causal relationships between physical variables and temporal characteristics of software modules are analyzed to determine how a certain state can be reached. This is done by developing timed fault trees which take the form of logical combinations of static trees relating the system parameters at different point in time. The resulting information concerning the hardware and software states can be used to eliminate unsafe execution paths and identify testing criteria for safety critical software functions.

Garrett, C. J.↗
NASA NTRS1993

An evaluation of software tools for the design and development of cockpit displays

The use of all-glass cockpits at the NASA Langley Research Center (LaRC) simulation facility has changed the means of design, development, and maintenance of instrument displays. The human-machine interface has evolved from a physical hardware device to a software-generated electronic display system. This has subsequently caused an increased workload at the facility. As computer processing power increases and the glass cockpit becomes predominant in facilities, software tools used in the design and development of cockpit displays are becoming both feasible and necessary for a more productive simulation environment. This paper defines LaRC requirements of a display software development tool and compares two available applications against these requirements. As a part of the software engineering process, these tools reduce development time, provide a common platform for display development, and produce exceptional real-time results.

Ellis, Thomas D., Jr.↗
NASA NTRS1988

Resource utilization during software development

This paper discusses resource utilization over the life cycle of software development and discusses the role that the current 'waterfall' model plays in the actual software life cycle. Software production in the NASA environment was analyzed to measure these differences. The data from 13 different projects were collected by the Software Engineering Laboratory at NASA Goddard Space Flight Center and analyzed for similarities and differences. The results indicate that the waterfall model is not very realistic in practice, and that as technology introduces further perturbations to this model with concepts like executable specifications, rapid prototyping, and wide-spectrum languages, we need to modify our model of this process.

Zelkowitz, Marvin V.↗
NASA NTRS1988

Computer systems and software engineering

The High Technologies Laboratory (HTL) was established in the fall of 1982 at the University of Houston Clear Lake. Research conducted at the High Tech Lab is focused upon computer systems and software engineering. There is a strong emphasis on the interrelationship of these areas of technology and the United States' space program. In Jan. of 1987, NASA Headquarters announced the formation of its first research center dedicated to software engineering. Operated by the High Tech Lab, the Software Engineering Research Center (SERC) was formed at the University of Houston Clear Lake. The High Tech Lab/Software Engineering Research Center promotes cooperative research among government, industry, and academia to advance the edge-of-knowledge and the state-of-the-practice in key topics of computer systems and software engineering which are critical to NASA. The center also recommends appropriate actions, guidelines, standards, and policies to NASA in matters pertinent to the center's research. Results of the research conducted at the High Tech Lab/Software Engineering Research Center have given direction to many decisions made by NASA concerning the Space Station Program.

Mckay, Charles W.↗
NASA NTRS1988

Software engineering as an engineering discipline

The following topics are discussed in the context of software engineering: early use of the term; the 1968 NATO conference; Barry Boehm's definition; four requirements fo software engineering; and additional criteria for software engineering. Additionally, the four major requirements for software engineering--computer science, mathematics, engineering disciplines, and excellent communication skills--are discussed. The presentation is given in vugraph form.

Berard, Edward V.↗
NASA NTRS1988

Software engineering as an engineering discipline

The goals of the Software Engineering Institute's Education Program are as follows: to increase the number of highly qualified software engineers--new software engineers and existing practitioners; and to be the leading center of expertise for software engineering education and training. A discussion of these goals is presented in vugraph form.

Gibbs, Norman↗
NASA NTRS1992

Applying reliability models to the maintenance of Space Shuttle software

Software reliability models provide the software manager with a powerful tool for predicting, controlling, and assessing the reliability of software during maintenance. We show how a reliability model can be effectively employed for reliability prediction and the development of maintenance strategies using the Space Shuttle Primary Avionics Software Subsystem as an example.

Schneidewind, Norman F.↗
NASA NTRS1993

Sculpting in cyberspace: Parallel processing the development of new software

Stimulating creativity in problem solving, particularly where software development is involved, is applicable to many disciplines. Metaphorical thinking keeps the problem in focus but in a different light, jarring people out of their mental ruts and sparking fresh insights. It forces the mind to stretch to find patterns between dissimilar concepts, in the hope of discovering unusual ideas in odd associations (Technology Review January 1993, p. 37). With a background in Engineering and Visual Design from MIT, I have for the past 30 years pursued a career as a sculptor of interdisciplinary monumental artworks that bridge the fields of science, engineering and art. Since 1979, I have pioneered the application of computer simulation to solve the complex problems associated with these projects. A recent project for the roof of the Carnegie Science Center in Pittsburgh made particular use of the metaphoric creativity technique described above. The problem-solving process led to the creation of hybrid software combining scientific, architectural and engineering visualization techniques. David Steich, a Doctoral Candidate in Electrical Engineering at Penn State, was commissioned to develop special software that enabled me to create innovative free-form sculpture. This paper explores the process of inventing the software through a detailed analysis of the interaction between an artist and a computer programmer.

Fisher, Rob↗
NASA NTRS1994

Using formal specification in the Guidance and Control Software (GCS) experiment. Formal design and verification technology for life critical systems

The goal of this task was to investigate how formal methods could be incorporated into a software engineering process for flight-control systems under DO-178B and to demonstrate that process by developing a formal specification for NASA's Guidance and Controls Software (GCS) Experiment. GCS is software to control the descent of a spacecraft onto a planet's surface. The GCS example is simplified from a real example spacecraft, but exhibits the characteristics of realistic spacecraft control software. The formal specification is written in Larch.

Weber, Doug↗
NASA NTRS1992

Software Management Environment (SME) concepts and architecture, revision 1

This document presents the concepts and architecture of the Software Management Environment (SME), developed for the Software Engineering Branch of the Flight Dynamic Division (FDD) of GSFC. The SME provides an integrated set of experience-based management tools that can assist software development managers in managing and planning flight dynamics software development projects. This document provides a high-level description of the types of information required to implement such an automated management tool.

Hendrick, Robert↗
NASA NTRS1993

An information model for use in software management estimation and prediction

This paper describes the use of cluster analysis for determining the information model within collected software engineering development data at the NASA/GSFC Software Engineering Laboratory. We describe the Software Management Environment tool that allows managers to predict development attributes during early phases of a software project and the modifications we propose to allow it to develop dynamic models for better predictions of these attributes.

Li, Ningda R.↗
NASA NTRS1993

Proceedings of the Eighteenth Annual Software Engineering Workshop

The workshop provided a forum for software practitioners from around the world to exchange information on the measurement, use, and evaluation of software methods, models, and tools. This year, approximately 450 people attended the workshop, which consisted of six sessions on the following topics: the Software Engineering Laboratory, measurement, technology assessment, advanced concepts, process, and software engineering issues in NASA. Three presentations were given in each of the topic areas. The content of those presentations and the research papers detailing the work reported are included in these proceedings. The workshop concluded with a tutorial session on how to start an Experience Factory.

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