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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 559 records · Page 31

All sources NASA NTRS DOE OSTI

NASA NTRS1985

Hot-spot durability testing of amorphous cells and modules

This paper discusses the results of a study to determine the hot-spot susceptibility of amorphous-silicon (a-Si) cells and modules, and to provide guidelines for reducing that susceptibility. Amorphous-Si cells are shown to have hot-spot susceptibility levels similar to crystalline-silicon (C-Si) cells. This premise leads to the fact that the same general guidelines must apply to protecting a-Si cells from hot-spot stressing that apply to C-Si cells. Recommendations are made on ways of reducing a-Si module hot-spot susceptibility including the traditional method of using bypass diodes and a new method unique to thin-film cells, limiting the string current by limiting cell area.

Gonzalez, Charles↗

NASA NTRS1987

Research papers and publications (1981-1987): Workload research program

An annotated bibliography of the research reports written by participants in NASA's Workload Research Program since 1981 is presented, representing the results of theoretical and applied research conducted at Ames Research Center and at universities and industrial laboratories funded by the program. The major program elements included: 1) developing an understanding of the workload concept; 2) providing valid, reliable, and practical measures of workload; and 3) creating a computer model to predict workload. The goal is to provide workload-related design principles, measures, guidelines, and computational models. The research results are transferred to user groups by establishing close ties with manufacturers, civil and military operators of aerospace systems, and regulatory agencies; publishing scientific articles; participating in and sponsoring workshops and symposia; providing information, guidelines, and computer models; and contributing to the formulation of standards. In addition, the methods and theories developed have been applied to specific operational and design problems at the request of a number of industry and government agencies.

Hart, Sandra G.↗

NASA NTRS1987

Hot-spot qualification testing of concentrator modules

Results of a study to determine the hot-spot susceptibility of concentrator cells, to provide a hot-spot qualification test for concentrator modules, and to provide guidelines for reducing hot-spot susceptibility are presented. Hot-spot heating occurs in a photovoltaic module when the short-circuit current of a cell is lower than the string operating current, forcing the cell into reverse bias with a concurrent power dissipation. Although the basis for the concentrator-module hot-spot qualification test is the test developed for flat-plate modules, issues such as providing cell illumination introduce additional complexities into the testing procedure. The results indicate that the same general guidelines apply to protecting concentrator modules from hot-spot stressing as apply to flat-plate modules, and recommendations are made on the number of bypass diodes required per given number of series cells per module or source circuit. A method for determining the cell temperature in the laboratory or in the field is discussed.

Gonzalez, C. C.↗

NASA NTRS1988

Orbiter environment at S- and Ku-band frequencies

Detailed measurements of the electric field strength associated with the Ku-band radar and S-band communication link were made by the Plasma Diagnostics Package (PDP) on STS 51F. These measurements were made while the PDP was attached to the Remote Manipulation System arm and again while the PDP was released as a subsatellite. The results indicate that cargo elements that remain inside of the scan limits of the radar should experience fields less than 2 V/m and that elements that may encounter the main beam can use 300 V/m as a design guideline with adequate safety margin. S-band fields tended to be several dB lower than worst-case predictions. Safe design practice indicates that an electric field E = 100/r (r in meters) should be used as a guideline for deployable systems. S-band electric fields within the cargo bay envelope should be less than 2 V/m even with edge diffraction effects and reflections from other payloads taken into account. The absolute accuracy of these measurements is about 2 dB.

Murphy, G. B.↗

NASA NTRS1988

Coping with all the earth science data

A report on the NASA-sponsored Earth Science and Applications Data Systems (ESADS) Workshop is presented. The ESADS report is reviewed and the task groups of the workshop are listed. The program set up to implement the recommendations of the workshop is discussed. The priorities of the ESADS committee recommendations include the development of standards and guidelines for data and metadata exchange, the creation of interoperable catalogs and directories, the development of guidelines for ancillary data archives, development of standard user interfaces, providing greater bandwidth in the user environment, collecting information about data storage technologies, and providing improved network connectivity.

Kahn, Ralph↗

NASA NTRS1988

Using full-mission simulation for human factors research in air transport operations

This study examined state-of-the-art mission oriented simulation and its use in human factors research. Guidelines were developed for doing full-mission human factors research on crew member behavior during simulated air transport operations. The existing literature was reviewed. However, interviews with experienced investigators provided the most useful information. The fundamental scientific and practical issues of behavioral research in a simulation environment are discussed. Guidelines are presented for planning, scenario development, and the execution of behavioral research using full-mission simulation in the context of air transport flight operations . Research is recommended to enhance the validity and productivity of full-mission research by: (1) validating the need for high-fidelity simulation of all major elements in the operational environment, (2) improving methods for conducting full-mission research, and (3) examining part-task research on specific problems through the use of vehicles which contain higher levels of abstraction (and lower fidelity) of the operational environment.

Orlady, Harry W.↗

NASA NTRS1988

Human adaptation to isolated and confined environments: Preliminary findings of a seven month Antarctic winter-over human factors study

This field study was conducted during the last decade of an austral winter-over at Palmer Station in the Antarctic. The purpose of the study was to understand temporal patterns in physiological arousal and psychological mood over the course of the mission. The investigators were principally interested in how people adapted over time to chronic and acute stressors, and how people use and modify their built environment. Physiological and psychological data were collected several times a week, and information on behavior and the use of physical facilities was collected monthly. Physiological and psychological data were compared with social changes in the setting toward the development of a sequential model of human-environment transactional relationships. Based on the study results, guidelines for design of future isolated and confined environments (ICEs) included: plan space for items which make people feel at home, provide materials to allow people to personalize their environment, allow for flexible environments, provide areas for visual and auditory privacy, equip areas for socializing and remove them from private areas, and provide facilities for exercise and for projects involving physical activity. The study offers guidelines about patterns of adaption that could be expected in an ICE, discusses how these settings can be programmed to facilitate successful adjustment, and provides information about how to design future ICE habitats to maximize a healthy living environment.

Evans, Gary W.↗

NASA NTRS1988

Ada in AI or AI in Ada. On developing a rationale for integration

The use of Ada as an Artificial Intelligence (AI) language is gaining interest in the NASA Community, i.e., by parties who have a need to deploy Knowledge Based-Systems (KBS) compatible with the use of Ada as the software standard for the Space Station. A fair number of KBS and pseudo-KBS implementations in Ada exist today. Currently, no widely used guidelines exist to compare and evaluate these with one another. The lack of guidelines illustrates a fundamental problem inherent in trying to compare and evaluate implementations of any sort in languages that are procedural or imperative in style, such as Ada, with those in languages that are functional in style, such as Lisp. Discussed are the strengths and weakness of using Ada as an AI language and a preliminary analysis provided of factors needed for the development of criteria for the integration of these two families of languages and the environments in which they are implemented. The intent for developing such criteria is to have a logical rationale that may be used to guide the development of Ada tools and methodology to support KBS requirements, and to identify those AI technology components that may most readily and effectively be deployed in Ada.

Collard, Philippe E.↗

NASA NTRS1990

Payload crew utilization for spacelab missions

Planned payload crew utilization on Spacelab mission are analyzed to establish trends and guidelines. The study included missions that have flow to date as well as those in planning. Available data were analyzed on the basis of four major timeline iterations that occur during mission design. Data were categorized and assessed by crewmember, flight day, and mission. Based on the results of this analysis, it was recommended that for the Requirements Review and Preliminary Design Review iterations the maximum utilization per shift should be 75 percent for the Payload Specialist (PS) and 65 percent for the Mission Specialist (MS); and for the basic and final iterations, the maximum utilization shift should be 85 percent for the PS and 75 percent for the MS. Additional recommendations include limiting the amount of activity during the first two shifts whenever possible and establishing a common set of guidelines for the calculations of crew utilization.

Ibrahim, K. Y.↗

NASA NTRS1990

Software verification plan for GCS

This verification plan is written as part of an experiment designed to study the fundamental characteristics of the software failure process. The experiment will be conducted using several implementations of software that were produced according to industry-standard guidelines, namely the Radio Technical Commission for Aeronautics RTCA/DO-178A guidelines, Software Consideration in Airborne Systems and Equipment Certification, for the development of flight software. This plan fulfills the DO-178A requirements for providing instructions on the testing of each implementation of software. The plan details the verification activities to be performed at each phase in the development process, contains a step by step description of the testing procedures, and discusses all of the tools used throughout the verification process.

Dent, Leslie A.↗

NASA NTRS1990

GCS plan for software aspects of certification

As part of the Guidance and Control Software (GCS) research project being sponsored by NASA to evaluate the failure processes of software, standard industry software development procedures are being employed. To ensure that these procedures are authentic, the guidelines outlined in the Radio Technical Commission for Aeronautics (RTCA/DO-178A document entitled, software considerations in airborne systems and equipment certification, were adopted. A major aspect of these guidelines is proper documentation. As such, this report, the plan for software aspects of certification, was produced in accordance with DO-178A. An overview is given of the GCS research project, including the goals of the project, project organization, and project schedules. It also specifies the plans for all aspects of the project which relate to the certification of the GCS implementations developed under a NASA contract. These plans include decisions made regarding the software specification, accuracy requirements, configuration management, implementation development and verification, and the development of the GCS simulator.

Shagnea, Anita M.↗

NASA NTRS1989

A review of gear housing dynamics and acoustics literature

A review of the available literature on gear housing vibration and noise radiation is presented. Analytical and experimental methodologies used for bearing dynamics, housing vibration and noise, mounts and suspensions, and the overall gear and housing system are discussed. Typical design guidelines, as outlined by various investigators, are also included. Results of this review indicate that although many attempts were made to characterize the dynamics of gearbox system components, no comprehensive set of design criteria currently exist. Moreover, the literature contains conflicting reports concerning relevant design guidelines.

Lim, Teik Chin↗

NASA NTRS1989

Establishing viable task domains for telerobot demonstrations

A suite of telerobotic tasks has been compiled and assessed for the purpose of selecting viable tasks for near and far term laboratory demonstrations. The primary intent of developing the task is to provide some technical guidelines, with supporting data, for focusing laboratory demonstrations toward application domains that address a wide array of potential telerobot tasks and required technologies. This wide application would then result in a rich technology development environment to meet the broad task requirements of a system such as the Flight Telerobot Servicer. The methodology and results of the telerobot task assessment are described, including a ranking of the final select suite of major tasks. The presented along with guidelines for both interpreting the task ranking results and setting programmatic objectives based on these results. Detailed data about the task candidates and their respective levels of complexity, task primitive actions, and the actual relative measures of task worth as associated with key tradeoff variables such as cost, available research resources, technology availability, and importance to the user community are also presented.

Zimmerman, Wayne↗

NASA NTRS1990

Simultaneous control and structure design for large space structures

The problem of developing design guidelines for the simultaneous selection of control and structural parameters is addressed. One guideline is offered for the case of vibration suppression due to disturbances. The effect of structural design changes is examined by means of a parameterized LQG compensator. It is shown that using the LQG design provides a simple means to evaluate simultaneous control and design changes.

Kosut, Robert L.↗

NASA NTRS1991

An interagency space nuclear propulsion safety policy for SEI - Issues and discussion

An interagency Nuclear Safety Policy Working Group (NSPWG) was chartered to recommend nuclear safety policy, requirements, and guidelines for the Space Exploration Initiative nuclear propulsion program to facilitate the implementation of mission planning and conceptual design studies. The NSPWG developed a top level policy to provide the guiding principles for the development and implementation of the nuclear propulsion safety program and the development of Safety Functional Requirements. In addition, the NSPWG reviewed safety issues for nuclear propulsion and recommended top level safety requirements and guidelines to address these issues. Safety topics include reactor start-up, inadvertent criticality, radiological release and exposure, disposal, entry, safeguards, risk/reliability, operational safety, ground testing, and other considerations. In this paper the emphasis is placed on the safety policy and the issues and considerations that are addressed by the NSPWG recommendations.

Marshall, A. C.↗

NASA NTRS1991

Management of the Space Station Freedom onboard local area network

An operational approach is proposed to managing the Data Management System Local Area Network (LAN) on Space Station Freedom. An overview of the onboard LAN elements is presented first, followed by a proposal of the operational guidelines by which management of the onboard network may be effected. To implement the guidelines, a recommendation is then presented on a set of network management parameters which should be made available in the onboard Network Operating System Computer Software Configuration Item and Fiber Distributed Data Interface firmware. Finally, some implications for the implementation of the various network management elements are discussed.

Miller, Frank W.↗

NASA NTRS1991

Human factors issues in the design of user interfaces for planning and scheduling

The purpose is to provide and overview of human factors issues that impact the effectiveness of user interfaces to automated scheduling tools. The following methods are employed: (1) a survey of planning and scheduling tools; (2) the identification and analysis of human factors issues; (3) the development of design guidelines based on human factors literature; and (4) the generation of display concepts to illustrate guidelines.

Murphy, Elizabeth D.↗

NASA NTRS1991

Software Engineering Laboratory (SEL) Ada performance study report

The goals of the Ada Performance Study are described. The methods used are explained. Guidelines for future Ada development efforts are given. The goals and scope of the study are detailed, and the background of Ada development in the Flight Dynamics Division (FDD) is presented. The organization and overall purpose of each test are discussed. The purpose, methods, and results of each test and analyses of these results are given. Guidelines for future development efforts based on the analysis of results from this study are provided. The approach used on the performance tests is discussed.

Booth, Eric W.↗