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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 307 records · Page 17

Timeline Resource Analysis Program (TRAP): User's manual and program document

The Timeline Resource Analysis Program (TRAP), developed for scheduling and timelining problems, is described. Given an activity network, TRAP generates timeline plots, resource histograms, and tabular summaries of the network, schedules, and resource levels. It is written in ANSI FORTRAN for the Honeywell SIGMA 5 computer and operates in the interactive mode using the TEKTRONIX 4014-1 graphics terminal. The input network file may be a standard SIGMA 5 file or one generated using the Interactive Graphics Design System. The timeline plots can be displayed in two orderings: according to the sequence in which the tasks were read on input, and a waterfall sequence in which the tasks are ordered by start time. The input order is especially meaningful when the network consists of several interacting subnetworks. The waterfall sequence is helpful in assessing the project status at any point in time.

Sessler, J. G.↗

Float Zone Workshop, introduction

The purposes of the float zone working group are summarized. Present and proposed U.S. and European research programs are listed, and power needs for float zoning surveyed. A 1981 to 1991 schedule for development efforts is presented.

Kern, E. L.↗

Hot Microfissuring in Nickel Alloy

Experiments in intergranular cracking of nickel alloy near solidus temperature discussed in contractor report. Purpose of investigation development of schedule for welding, casting, forging, or other processing of alloy without causing microfissuring.

Thompson, R. G.↗

Space Station needs, attributes and architectural options, volume 2, book 3: Cost and programmatics

The cost and programmatic considerations which integrate mission requirements and architectural options into a cohesive system for exploitation of space opportunities within affordable limits are discussed. The mission requirements, baseline architecture, a top level baseline schedule, and acquisition costs are summarized. The work breakdown structure (WBS) used to structure the program, and the WBS dictionary are included. The costing approach used, including the operation of the primary costing tool, the SPACE cost model are described. The rationale for the choice of cost estimating relationships is given and costs at the module level are shown. Detailed costs at the subsystem level are shown. The baseline schedule and annual funding profiles are provided. Alternate schedules are developed to provide different funding profiles. Alternate funding sources are discussed and foreign and contractor participation is outlined. The results of the benefit analysis are given and the accrued benefits deriving from an implemented space station program are outlined.

Source record↗

The formation of stellar systems from interstellar molecular clouds

The observational and theoretical study of regions of continuing star formation promises greater insight into the physical conditions and events associated with the formation of the solar system, and elucidates the role played by star formation in the evolutionary cycle which seems to dominate interstellar material's processing by successive generations of stars in the spiral galaxies. Novel astronomical methods incorporated by the new facilities scheduled for development in the 1980s may yield substantial advancements in star formation process theory; most significant among these efforts will be the identification and examination of the elusive protostellar collapse phase of both star and planetary system formation.

Gehrz, R. D.↗

Expert systems development and application

Current research in the application of expert systems to problems in the flight research environment is discussed. In what is anticipated to be a broad research area, a real time expert system flight status monitor has been identified as the initial project. This real time expert system flight status monitor is described in terms of concept, application, development, and schedule.

Duke, E. L.↗

Study of onboard expert systems to augment space shuttle and space station autonomy

The feasibility of onboard crew activity planning was examined. The use of expert systems technology to aid crewmembers in locating stowed equipment was also investigated. The crew activity planning problem, along with a summary of past and current research efforts, was discussed in detail. The requirements and specifications used to develop the crew activity planning system was also defined. The guidelines used to create, develop, and operate the MFIVE Crew Scheduler and Logistics Clerk were discussed. Also discussed is the mathematical algorithm, used by the MFIVE Scheduler, which was developed to aid in optimal crew activity planning.

Kurtzman, C. R.↗

Prototype resupply scheduler

Resupply scheduling for the Space Station presents some formidable logistics problems. One of the most basic problems is assigning supplies to a series of shuttle resupply missions. A prototype logistics expert system which constructs resupply schedules was developed. This prototype is able to reconstruct feasible resupply plans. In addition, analysts can use the system to evaluate the impact of adding, deleting or modifying launches, cargo space, experiments, etc.

Tanner, Steve↗

ACTS - The first step toward a switchboard in the sky

The Advanced Communications Technology Satellite (ACTS), now under development and scheduled for launch in May 1992, is presently the main focus of NASA's communications program. Key technologies for ACTS include electronically hopping spot beam antennas, on-board processing and circuit switching, and Ka-band transmission.

Naderi, F. Michael↗

Get-Away tether experiment - Experimental plans

The experimental capabilities of the Get-Away Tether Experiment (GATE) are presented and a series of demonstration mission are proposed. The GATE is a free-flying tether system that will develop or demonstrate technology in the areas of tether dynamics (deployment and stabilization, retrieval, stationkeeping, and severance), tether electrodynamics, micrometeor hazards to tethers, and disturbance rejection. The system consists of two subsatellites connected by 1 km of tether. The free-flying system is ejected from the Orbiter via a Getaway Special (GAS) canister. Two dynamics missions are profiled along with a description of electrodynamic mission capabilities. The dynamic interactions of the end body and tether may be observed from the Orbiter or from an on-board video tracking system. Hence, GATE provides a unique, low cost capability to demonstrate various tether technologies, and address critical design and safety issues associated with future tether applications. An assessment of the significant measurable parameters and associated instrumentation is given. Future work and system development projection schedules are also outlined.

Greene, Michael↗

Software design with fuzzy requirements (A case study)

The author describes the resource allocation and planning helper (RALPH) scheduling system developed at NASA's Jet Propulsion Laboratory. RALPH addresses the concerns of designing software systems to minimize the need to recode for changes and upgrades; this concern is acute when requirements are uncertain or changing. Determining requirements, understanding the problem, designing for change, and tradeoffs are also discussed.

Werntz, David G.↗

Knowledge representation into Ada parallel processing

The Knowledge Representation into Ada Parallel Processing project is a joint NASA and Air Force funded project to demonstrate the execution of intelligent systems in Ada on the Charles Stark Draper Laboratory fault-tolerant parallel processor (FTPP). Two applications were demonstrated - a portion of the adaptive tactical navigator and a real time controller. Both systems are implemented as Activation Framework Objects on the Activation Framework intelligent scheduling mechanism developed by Worcester Polytechnic Institute. The implementations, results of performance analyses showing speedup due to parallelism and initial efficiency improvements are detailed and further areas for performance improvements are suggested.

Masotto, Tom↗

Launch site integration for mixed fleet operations

Launch site impacts and integration planning issues are presented to support launch operations for a mixed vehicle fleet (manned and cargo). Proposed ground systems and launch site configurations are described. Prelaunch processing scenarios and schedules are developed for candidate launch vehicles. Earth-to-orbit (ETO) vehicle architectures are presented to meet future launch requirements, including the Space Exploration Initiative (SEI). Flight vehicle design recommendations to enhance launch processing are discussed. The significance of operational designs for future launch vehicles is shown to be a critical factor in planning for mixed fleet launch site operations.

Scott, L. P.↗

Earth Sciences Data and Information System (ESDIS) program planning and evaluation methodology development

An Earth Sciences Data and Information System (ESDIS) Project Management Plan (PMP) is prepared. An ESDIS Project Systems Engineering Management Plan (SEMP) consistent with the developed PMP is also prepared. ESDIS and related EOS program requirements developments, management and analysis processes are evaluated. Opportunities to improve the effectiveness of these processes and program/project responsiveness to requirements are identified. Overall ESDIS cost estimation processes are evaluated, and recommendations to improve cost estimating and modeling techniques are developed. ESDIS schedules and scheduling tools are evaluated. Risk assessment, risk mitigation strategies and approaches, and use of risk information in management decision-making are addressed.

Dickinson, William B.↗

The Impact of Information Technology on the Design, Development, and Implementation of a Lunar Exploration Mission

From the beginning to the present expeditions to the Moon have involved a large investment of human labor. This has been true for all aspects of the process, from the initial design of the mission, whether scientific or technological, through the development of the instruments and the spacecraft, to the flight and operational phases. In addition to the time constraints that this situation imposes, there is also a significant cost associated with the large labor costs. As a result lunar expeditions have been limited to a few robotic missions and the manned Apollo program missions of the 1970s. With the rapid rise of the new information technologies, new paradigms are emerging that promise to greatly reduce both the time and cost of such missions. With the rapidly increasing capabilities of computer hardware and software systems, as well as networks and communication systems, a new balance of work is being developed between the human and the machine system. This new balance holds the promise of greatly increased exploration capability, along with dramatically reduced design, development, and operating costs. These new information technologies, utilizing knowledge-based software and very highspeed computer systems, will provide new design and development tools, scheduling mechanisms, and vehicle and system health monitoring capabilities that have hitherto been unavailable to the mission and spacecraft designer and the system operator. This paper will utilize typical lunar missions, both robotic and crewed, as a basis to describe and illustrate how these new information system technologies could be applied to all aspects such missions. In particular, new system design tradeoff tools will be described along with technologies that will allow a very much greater degree of autonomy of exploration vehicles than has heretofore been possible. In addition, new information technologies that will significantly reduce the human operational requirements will be discussed.

Gross, Anthony R.↗

EELV Booster Assist Options for CEV

Medium lift EELVs may still play a role in manned space flight. To be considered for manned flight, medium lift EELVs must address the short comings in their current boost assist motors. Two options exist: redesign and requalify the solid rocket motors. Replace solid rocket motors (SRMs) with hybrid rocket motors. Hybrid rocket motors are an attractive alternative. They are safer than SRMs. The TRL's Lockheed Martin Small Launch Vehicle booster development substantially lowers the development risk, cost risk, and the schedule risk for developing hybrid boost assist for EELVs. Hybrid boosters testability offsets SRMs higher inherent reliability.Hybrid booster development and recurring costs are lower than SRMs. Performance gains are readily achieved.

McNeal, Curtis, Jr.↗

Postural Control Disturbances Produced By Exposure to HMD and Dome Vr Systems

Two critical and unresolved human factors issues in VR systems are: 1) potential "cybersickness", a form of motion sickness which is experienced in virtual worlds, and 2) maladaptive sensorimotor performance following exposure to VR systems. Interestingly, these aftereffects are often quite similar to adaptive sensorimotor responses observed in astronauts during and/or following space flight. Most astronauts and cosmonauts experience perceptual and sensorimotor disturbances during and following space flight. All astronauts exhibit decrements in postural control following space flight. It has been suggested that training in virtual reality (VR) may be an effective countermeasure for minimizing perceptual and/or sensorimotor disturbances. People adapt to consistent, sustained alterations of sensory input such as those produced by microgravity, and experimentally-produced stimulus rearrangements (e.g., reversing prisms, magnifying lenses, flight simulators, and VR systems). Adaptation is revealed by aftereffects including perceptual disturbances and sensorimotor control disturbances. The purpose of the current study was to compare disturbances in postural control produced by dome and head-mounted virtual environment displays. Individuals recovered from motion sickness and the detrimental effects of exposure to virtual reality on postural control within one hour. Sickness severity and initial decrements in postural equilibrium decreases over days, which suggests that subjects become dual-adapted over time. These findings provide some direction for developing training schedules for VR users that facilitate adaptation, and address safety concerns about aftereffects.

Harm, D. L.↗

Shortwave Radiation

Accurate shortwave radiation data is critical to evapotranspiration (ET) models used for developing irrigation schedules to optimize crop production while saving water, minimizing fertilizer, herbicide, and pesticide applications, reducing soil erosion, and protecting surface and ground water quality. Low cost silicon cell pyranometers have proven to be sufficiently accurate and robust for widespread use in agricultural applications under unobstructed daylight conditions. More expensive thermopile pyranometers are required for use as calibration standards and measurements under light with unique spectral properties (electric lights, under vegetation, in greenhouses and growth chambers). Routine cleaning, leveling, and annual calibration checks will help to ensure the integrity of long-term data.

Klassen, Steve↗