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At least 1,315 records · Page 73

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NASA NTRS1989

Additional software developments wanted for modeling and control of flexible space systems

Existing modeling and control software packages are either inadequate or inefficient for applications to flexible space structures. Some additional software developments are wanted for effective design and evaluation of the control systems. The following are discussed: (1) linear-quadratic optimal regulators as usual can be designed using various modern control design software packages, (2) modal dashpots are very effective output-feedback vibration controllers for flexible structures, not only effective for augmenting a small amount of active damping to a large number of vibration modes (like the so-called low-authority structural controllers), but also effective for quick suppression of large vibrations (like high-authority structural controllers), and (3) the actual performance of any control design needs to be evaluated against a faithful model of the flexible structure to be controlled. The potential of destabilization or serious performance degradation needs to be detected by numerical simulation of the structure with the control loops being closed.

Lin, Jiguan Gene↗

NASA NTRS1988

A nonparametric software reliability growth model

Miller and Sofer have presented a nonparametric method for estimating the failure rate of a software program. The method is based on the complete monotonicity property of the failure rate function, and uses a regression approach to obtain estimates of the current software failure rate. This completely monotone software model is extended. It is shown how it can also provide long-range predictions of future reliability growth. Preliminary testing indicates that the method is competitive with parametric approaches, while being more robust.

Miller, Douglas R.↗

NASA NTRS1990

Improving a data-acquisition software system with abstract data type components

Abstract data types and object-oriented design are active research areas in computer science and software engineering. Much of the interest is aimed at new software development. Abstract data type packages developed for a discontinued software project were used to improve a real-time data-acquisition system under maintenance. The result saved effort and contributed to a significant improvement in the performance, maintainability, and reliability of the Goldstone Solar System Radar Data Acquisition System.

Howard, S. D.↗

NASA NTRS1990

Software quality assurance plan for GCS

The software quality assurance (SQA) function for the Guidance and Control Software (GCS) project which is part of a software error studies research program is described. The SQA plan outlines all of the procedures, controls, and audits to be carried out by the SQA organization to ensure adherence to the policies, procedures, and standards for the GCS project.

Duncan, Stephen E.↗

NASA NTRS1989

The JPL telerobot operator control station. Part 2: Software

The Operator Control Station of the Jet Propulsion Laboratory (JPL)/NASA Telerobot Demonstrator System provides the man-machine interface between the operator and the system. It provides all the hardware and software for accepting human input for the direct and indirect (supervised) manipulation of the robot arms and tools for task execution. Hardware and software are also provided for the display and feedback of information and control data for the operator's consumption and interaction with the task being executed. The software design of the operator control system is discussed.

Kan, Edwin P.↗

NASA NTRS1990

Documenting the decision structure in software development

Current software development paradigms focus on the products of the development process. Much of the decision making process which produces these products is outside the scope of these paradigms. The Decision-Based Software Development (DBSD) paradigm views the design process as a series of interrelated decisions which involve the identification and articulation of problems, alternates, solutions and justifications. Decisions made by programmers and analysts are recorded in a project data base. Unresolved problems are also recorded and resources for their resolution are allocated by management according to the overall development strategy. This decision structure is linked to the products affected by the relevant decision and provides a process oriented view of the resulted system. Software maintenance uses this decision view of the system to understand the rationale behind the decisions affecting the part of the system to be modified. D-HyperCase, a prototype Decision-Based Hypermedia System is described and results of applying the DBSD approach during its development are presented.

Wild, J. Christian↗

NASA NTRS1989

Validation of NSSC-I software for the Hubble Space Telescope

This paper describes the simulation and test methods used to ensure that the NASA Standard Spacecraft Computer, Model 1, (NSSC-I) flight software for the Hubble Space Telescope properly carries out its requirements for control of scientific observations and for monitoring the health and safety of the payload. The hardware and software test environment is discussed. The different kinds of tests (unit, special real time, and stress tests) that are performed before the software is incorporated into the flight system are described, and the kinds of errors that each test category is best suited to find are listed. Finally, the limitations of the tests are discussed, and current plans for enhancing the test environment are outlined.

Foley, Glenn↗

NASA NTRS1989

The embedded software life cycle - An expanded view

Six common issues that are encountered in the development of software for embedded computer systems are discussed from the perspective of their interrelationships with the development process and/or the system itself. Particular attention is given to concurrent hardware/software development, prototyping, the inaccessibility of the operational system, fault tolerance, the long life cycle, and inheritance. It is noted that the life cycle for embedded software must include elements beyond simply the specification and implementation of the target software.

Larman, Brian T.↗

NASA NTRS1990

Hardware-assisted software clock synchronization for homogeneous distributed systems

A clock synchronization scheme that strikes a balance between hardware and software solutions is proposed. The proposed is a software algorithm that uses minimal additional hardware to achieve reasonably tight synchronization. Unlike other software solutions, the guaranteed worst-case skews can be made insensitive to the maximum variation of message transit delay in the system. The scheme is particularly suitable for large partially connected distributed systems with topologies that support simple point-to-point broadcast algorithms. Examples of such topologies include the hypercube and the mesh interconnection structures.

Ramanathan, P.↗

NASA NTRS1991

Developing Confidence Limits For Reliability Of Software

Technique developed for estimating reliability of software by use of Moranda geometric de-eutrophication model. Pivotal method enables straightforward construction of exact bounds with associated degree of statistical confidence about reliability of software. Confidence limits thus derived provide precise means of assessing quality of software. Limits take into account number of bugs found while testing and effects of sampling variation associated with random order of discovering bugs.

Hayhurst, Kelly J.↗

NASA NTRS1991

Software-Design-Analyzer System

CRISP-90 software-design-analyzer system, update of CRISP-80, is set of computer programs constituting software tool for design and documentation of other software and supporting top-down, hierarchical, modular, structured methodologies for design and programming. Written in Microsoft QuickBasic.

Tausworthe, Robert C.↗

NASA NTRS1988

Towards a comprehensive framework for reuse: A reuse-enabling software evolution environment

Reuse of products, processes and knowledge will be the key to enable the software industry to achieve the dramatic improvement in productivity and quality required to satisfy the anticipated growing demand. Although experience shows that certain kinds of reuse can be successful, general success has been elusive. A software life-cycle technology which allows broad and extensive reuse could provide the means to achieving the desired order-of-magnitude improvements. The scope of a comprehensive framework for understanding, planning, evaluating and motivating reuse practices and the necessary research activities is outlined. As a first step towards such a framework, a reuse-enabling software evolution environment model is introduced which provides a basis for the effective recording of experience, the generalization and tailoring of experience, the formalization of experience, and the (re-)use of experience.

Basili, V. R.↗

NASA NTRS1988

A communication channel model of the software process

Beginning research into a noisy communication channel analogy of software development process productivity, in order to establish quantifiable behavior and theoretical bounds is discussed. The analogy leads to a fundamental mathematical relationship between human productivity and the amount of information supplied by the developers, the capacity of the human channel for processing and transmitting information, the software product yield (object size) the work effort, requirements efficiency, tool and process efficiency, and programming environment advantage. An upper bound to productivity is derived that shows that software reuse is the only means that can lead to unbounded productivity growth; practical considerations of size and cost of reusable components may reduce this to a finite bound.

Tausworthe, Robert C.↗

NASA NTRS1989

AdaNET Dynamic Software Inventory (DSI) prototype component acquisition plan

A component acquisition plan contains the information needed to evaluate, select, and acquire software and hardware components necessary for successful completion of the AdaNET Dynamic Software Inventory (DSI) Management System Prototype. This plan will evolve and be applicable to all phases of the DSI prototype development. Resources, budgets, schedules, and organizations related to component acquisition activities are provided. A purpose and description of a software or hardware component which is to be acquired are presented. Since this is a plan for acquisition of all components, this section is not applicable. The procurement activities and events conducted by the acquirer are described and who is responsible is identified, where the activity will be performed, and when the activities will occur for each planned procurement. Acquisition requirements describe the specific requirements and standards to be followed during component acquisition. The activities which will take place during component acquisition are described. A list of abbreviations and acronyms, and a glossary are contained.

Hanley, Lionel↗

NASA NTRS1990

Evaluation of the Trajectory Operations Applications Software Task (TOAST). Volume 2: Interview transcripts

The Trajectory Operations Applications Software Task (TOAST) is a software development project whose purpose is to provide trajectory operation pre-mission and real-time support for the Space Shuttle. The purpose of the evaluation was to evaluate TOAST as an Application Manager - to assess current and planned capabilities, compare capabilities to commercially-available off the shelf (COTS) software, and analyze requirements of MCC and Flight Analysis Design System (FADS) for TOAST implementation. As a major part of the data gathering for the evaluation, interviews were conducted with NASA and contractor personnel. Real-time and flight design users, orbit navigation users, the TOAST developers, and management were interviewed. Code reviews and demonstrations were also held. Each of these interviews was videotaped and transcribed as appropriate. Transcripts were edited and are presented chronologically.

Perkins, Sharon↗

NASA NTRS1990

Research into software executives for space operations support

Research concepts pertaining to a software (workstation) executive which will support a distributed processing command and control system characterized by high-performance graphics workstations used as computing nodes are presented. Although a workstation-based distributed processing environment offers many advantages, it also introduces a number of new concerns. In order to solve these problems, allow the environment to function as an integrated system, and present a functional development environment to application programmers, it is necessary to develop an additional layer of software. This 'executive' software integrates the system, provides real-time capabilities, and provides the tools necessary to support the application requirements.

Collier, Mark D.↗

NASA NTRS1990

Manager's handbook for software development, revision 1

Methods and aids for the management of software development projects are presented. The recommendations are based on analyses and experiences of the Software Engineering Laboratory (SEL) with flight dynamics software development. The management aspects of the following subjects are described: organizing the project, producing a development plan, estimating costs, scheduling, staffing, preparing deliverable documents, using management tools, monitoring the project, conducting reviews, auditing, testing, and certifying.

Source record↗

NASA NTRS1990

Continuation of research into software for space operations support, volume 1

A prototype workstation executive called the Hardware Independent Software Development Environment (HISDE) was developed. Software technologies relevant to workstation executives were researched and evaluated and HISDE was used as a test bed for prototyping efforts. New X Windows software concepts and technology were introduced into workstation executives and related applications. The four research efforts performed included: (1) Research into the usability and efficiency of Motif (an X Windows based graphic user interface) which consisted of converting the existing Athena widget based HISDE user interface to Motif demonstrating the usability of Motif and providing insight into the level of effort required to translate an application from widget to another; (2) Prototype a real time data display widget which consisted of research methods for and prototyping the selected method of displaying textual values in an efficient manner; (3) X Windows performance evaluation which consisted of a series of performance measurements which demonstrated the ability of low level X Windows to display textural information; (4) Convert the Display Manager to X Window/Motif which is the application used by NASA for data display during operational mode.

Collier, Mark D.↗