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NASA NTRS1992

Advanced ISDN satellite designs and experiments

The research performed by GTE Government Systems and the University of Colorado in support of the NASA Satellite Communications Applications Research (SCAR) Program is summarized. Two levels of research were undertaken. The first dealt with providing interim services Integrated Services Digital Network (ISDN) satellite (ISIS) capabilities that accented basic rate ISDN with a ground control similar to that of the Advanced Communications Technology Satellite (ACTS). The ISIS Network Model development represents satellite systems like the ACTS orbiting switch. The ultimate aim is to move these ACTS ground control functions on-board the next generation of ISDN communications satellite to provide full-service ISDN satellite (FSIS) capabilities. The technical and operational parameters for the advanced ISDN communications satellite design are obtainable from the simulation of ISIS and FSIS engineering software models of the major subsystems of the ISDN communications satellite architecture. Discrete event simulation experiments would generate data for analysis against NASA SCAR performance measure and the data obtained from the ISDN satellite terminal adapter hardware (ISTA) experiments, also developed in the program. The Basic and Option 1 phases of the program are also described and include the following: literature search, traffic mode, network model, scenario specifications, performance measures definitions, hardware experiment design, hardware experiment development, simulator design, and simulator development.

Pepin, Gerard R.↗

NASA NTRS1991

Case for real-time systems development - Quo vadis?

The paper focuses on the distinctive issues of computer-aided software engineering (CASE) products for the development of real-time systems. CASE technologies and associated standardization efforts are evolving from sets of conflicting interests. The majority of case products are intended for use in the development of management information systems. CASE products to support the development of large, complex real-time systems must provide additional capabilities. Generic concerns include the quality of the implementation of the required method for the phase of the system's development and whether the vendor is stable and committed to evolving the products in parallel with nonproprietary standards. The CASE market is undergoing considerable consolidation. The paper describes the major forces, cooperating entities, and remaining uncertainties that need to be weighed in near-term CASE procurements to limit risk of loss of investment in project time, trianing, and money.

Erb, Dona M.↗

NASA NTRS1991

Thermal Synthesizer System - An integrated approach to spacecraft thermal analysis

The Thermal Synthesizer System (TSS), which is being developed to meet the thermal analysis needs of Space Station Freedom and of the proposed Space Exploration Initiative missions, is examined. The key requirements and design goals to be met by TSS are summarized, and the software engineering and user interface design philosophy are reviewed. The basic architecture for all applications within TSS is described. An overview is given of the main features of each of the applications of TSS.

Panczak, Tim↗

NASA NTRS1992

Towards automated support for extraction of reusable components

A cost effective introduction of software reuse techniques requires the reuse of existing software developed in many cases without aiming at reusability. This paper discusses the problems related to the analysis and reengineering of existing software in order to reuse it. We introduce a process model for component extraction and focus on the problem of analyzing and qualifying software components which are candidates for reuse. A prototype tool for supporting the extraction of reusable components is presented. One of the components of this tool aids in understanding programs and is based on the functional model of correctness. It can assist software engineers in the process of finding correct formal specifications for programs. A detailed description of this component and an example to demonstrate a possible operational scenario are given.

Abd-El-hafiz, S. K.↗

NASA NTRS1992

On the nature of bias and defects in the software specification process

Implementation bias in a specification is an arbitrary constraint in the solution space. This paper describes the problem of bias. Additionally, this paper presents a model of the specification and design processes describing individual subprocesses in terms of precision/detail diagrams and a model of bias in multi-attribute software specifications. While studying how bias is introduced into a specification we realized that software defects and bias are dual problems of a single phenomenon. This was used to explain the large proportion of faults found during the coding phase at the Software Engineering Laboratory at NASA/GSFC.

Straub, Pablo A.↗

NASA NTRS1992

An improved classification tree analysis of high cost modules based upon an axiomatic definition of complexity

Identification of high cost modules has been viewed as one mechanism to improve overall system reliability, since such modules tend to produce more than their share of problems. A decision tree model was used to identify such modules. In this current paper, a previously developed axiomatic model of program complexity is merged with the previously developed decision tree process for an improvement in the ability to identify such modules. This improvement was tested using data from the NASA Software Engineering Laboratory.

Tian, Jianhui↗

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

Knowledge-intensive software design systems: Can too much knowledge be a burden?

While acknowledging the considerable benefits of domain-specific, knowledge-intensive approaches to automated software engineering, it is prudent to carefully examine the costs of such approaches, as well. In adding domain knowledge to a system, a developer makes a commitment to understanding, representing, maintaining, and communicating that knowledge. This substantial overhead is not generally associated with domain-independent approaches. In this paper, I examine the downside of incorporating additional knowledge, and illustrate with examples based on our experience in building the SIGMA system. I also offer some guidelines for developers building domain-specific systems.

Keller, Richard M.↗

NASA NTRS1992

CARDS: A blueprint and environment for domain-specific software reuse

CARDS (Central Archive for Reusable Defense Software) exploits advances in domain analysis and domain modeling to identify, specify, develop, archive, retrieve, understand, and reuse domain-specific software components. An important element of CARDS is to provide visibility into the domain model artifacts produced by, and services provided by, commercial computer-aided software engineering (CASE) technology. The use of commercial CASE technology is important to provide rich, robust support for the varied roles involved in a reuse process. We refer to this kind of use of knowledge representation systems as supporting 'knowledge-based integration.'

Wallnau, Kurt C.↗

NASA NTRS1991

Intelligent systems technology infrastructure for integrated systems

A system infrastructure must be properly designed and integrated from the conceptual development phase to accommodate evolutionary intelligent technologies. Several technology development activities were identified that may have application to rendezvous and capture systems. Optical correlators in conjunction with fuzzy logic control might be used for the identification, tracking, and capture of either cooperative or non-cooperative targets without the intensive computational requirements associated with vision processing. A hybrid digital/analog system was developed and tested with a robotic arm. An aircraft refueling application demonstration is planned within two years. Initially this demonstration will be ground based with a follow-on air based demonstration. System dependability measurement and modeling techniques are being developed for fault management applications. This involves usage of incremental solution/evaluation techniques and modularized systems to facilitate reuse and to take advantage of natural partitions in system models. Though not yet commercially available and currently subject to accuracy limitations, technology is being developed to perform optical matrix operations to enhance computational speed. Optical terrain recognition using camera image sequencing processed with optical correlators is being developed to determine position and velocity in support of lander guidance. The system is planned for testing in conjunction with Dryden Flight Research Facility. Advanced architecture technology is defining open architecture design constraints, test bed concepts (processors, multiple hardware/software and multi-dimensional user support, knowledge/tool sharing infrastructure), and software engineering interface issues.

Lum, Henry↗

NASA NTRS1993

The theory of interface slicing

Interface slicing is a new tool which was developed to facilitate reuse-based software engineering, by addressing the following problems, needs, and issues: (1) size of systems incorporating reused modules; (2) knowledge requirements for program modification; (3) program understanding for reverse engineering; (4) module granularity and domain management; and (5) time and space complexity of conventional slicing. The definition of a form of static program analysis called interface slicing is addressed.

Beck, Jon↗

NASA NTRS1992

Representation and presentation of requirements knowledge

An approach to representation and presentation of knowledge used in the ARIES, an experimental requirements/specification environment, is described. The approach applies the notion of a representation architecture to the domain of software engineering and incorporates a strong coupling to a transformation system. It is characterized by a single highly expressive underlying representation, interfaced simultaneously to multiple presentations, each with notations of differing degrees of expressivity. This enables analysts to use multiple languages for describing systems and have these descriptions yield a single consistent model of the system.

Johnson, W. L.↗

NASA NTRS1991

AIAA/NASA International Symposium on Space Information Systems, 2nd, Pasadena, CA, Sept. 17-19, 1990, Proceedings. Vols. 1 & 2

These proceedings overview major space information system projects and lessons learned from current missions. Other topics include the science information system requirements for the 1990s, an information systems design approach for major programs, the technology needs and projections, the standards for space data information systems, the artificial intelligence technology and applications, international interoperability, and spacecraft data systems and architectures advanced communications. Other topics include the software engineering technology and applications, the multimission multidiscipline information system architectures, the distributed planning and scheduling systems and operations, and the computer and information systems architectures. Paper presented include prospects for scientific data analysis systems for solar-terrestrial physics in the 1990s, the Columbus data management system, data storage technologies for the future, the German aerospace research establishment, and launching artificial intelligence in NASA ground systems.

Tavenner, Leslie A.↗

NASA NTRS1992

Software issues in three dimensional continuum shape optimization employing boundary formulations

The paper addresses the issue of how individual computational techniques for the accurate and economical calculation of information required for large-scale 3D continuum structural shape optimization via boundary element analysis (BEA) formulations can be prudently selected and incorporated in large-scale BEA programs, employing either direct or iterative equation solvers. A series of techniques that allows for the incorporation of economical shape design sensitivity analysis capability with a minimal amount of software development is described. The use of reanalysis is shown to be the key ingredient associated with each of these techniques. It is concluded that, from a software engineering perspective, capabilities that facilitate 3D shape optimization can be implemented in BEA programs with only modest investments in program development.

Kane, James H.↗

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 NTRS1991

Towards automated support for extraction of reusable components

Abd-El-hafiz, S. K.↗

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 NTRS1991

Data systems and computer science programs: Overview

An external review of the Integrated Technology Plan for the Civil Space Program is presented. The topics are presented in viewgraph form and include the following: onboard memory and storage technology; advanced flight computers; special purpose flight processors; onboard networking and testbeds; information archive, access, and retrieval; visualization; neural networks; software engineering; and flight control and operations.

Smith, Paul H.↗