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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 685 records · Page 38

NASA Processes and Requirements for Conducting Human-in-the-Loop Closed Chamber Tests

NASA has specific processes and requirements that must be followed for tests involving human subjects to be conducted in a safe and effective manner. There are five distinct phases of test operations. Phase one, the test request phase, consists of those activities related to initiating, processing, reviewing, and evaluating the test request. Phase two, the test preparation phase consists of those activities related to planning, coordinating, documenting, and building up the test. Phase three, the test readiness phase consists of those activities related to verifying and reviewing the planned test operations. Phase four, the test activity phase, consists of all pretest operations, functional checkouts, emergency drills, and test operations. Phase five, the post test activity phase, consists of those activities performed once the test is completed, including briefings, documentation of anomalies, data reduction and archiving, and reporting. Project management processes must be followed for facility modifications and major test buildup, which include six phases: initiation and assessment, requirements evaluation, preliminary design, detailed design, use readiness review (URR) and acceptance. Compliance with requirements for safety and quality assurance are documented throughout the test buildup and test operation processes. Tests involving human subjects must be reviewed by the applicable Institutional Review Board (IRB).

Barta, Daniel J.↗

The historical development and basis of human factors guidelines for automated systems in aeronautical operations

In order to derive general design guidelines for automated systems a study was conducted on the utilization and acceptance of existing automated systems as currently employed in several commercial fields. Four principal study area were investigated by means of structured interviews, and in some cases questionnaires. The study areas were aviation, a both scheduled airline and general commercial aviation; process control and factory applications; office automation; and automation in the power industry. The results of over eighty structured interviews were analyzed and responses categoried as various human factors issues for use by both designers and users of automated equipment. These guidelines address such items as general physical features of automated equipment; personnel orientation, acceptance, and training; and both personnel and system reliability.

Ciciora, J. A.↗

Comparative evaluation operability of large space structure connectors

The evaluation of several connector concepts in the neutral buoyancy simulator is discussed. Parameters for evaluating the fasteners included subject comments and hardware damage. Evaluation results include a rank ordering of the candidates with descriptions of the acceptable and unacceptable points of each. General design recommendations established as a result of neutral buoyancy testing are defined. Recommendations include detailed hardware and operational design requirements.

Stokes, J. W.↗

Test/score/report: Simulation techniques for automating the test process

A Test/Score/Report capability is currently being developed for the Transportable Payload Operations Control Center (TPOCC) Advanced Spacecraft Simulator (TASS) system which will automate testing of the Goddard Space Flight Center (GSFC) Payload Operations Control Center (POCC) and Mission Operations Center (MOC) software in three areas: telemetry decommutation, spacecraft command processing, and spacecraft memory load and dump processing. Automated computer control of the acceptance test process is one of the primary goals of a test team. With the proper simulation tools and user interface, the task of acceptance testing, regression testing, and repeatability of specific test procedures of a ground data system can be a simpler task. Ideally, the goal for complete automation would be to plug the operational deliverable into the simulator, press the start button, execute the test procedure, accumulate and analyze the data, score the results, and report the results to the test team along with a go/no recommendation to the test team. In practice, this may not be possible because of inadequate test tools, pressures of schedules, limited resources, etc. Most tests are accomplished using a certain degree of automation and test procedures that are labor intensive. This paper discusses some simulation techniques that can improve the automation of the test process. The TASS system tests the POCC/MOC software and provides a score based on the test results. The TASS system displays statistics on the success of the POCC/MOC system processing in each of the three areas as well as event messages pertaining to the Test/Score/Report processing. The TASS system also provides formatted reports documenting each step performed during the tests and the results of each step. A prototype of the Test/Score/Report capability is available and currently being used to test some POCC/MOC software deliveries. When this capability is fully operational it should greatly reduce the time necessary to test a POCC/MOC software delivery, as well as improve the quality of the test process.

Hageman, Barbara H.↗

Political and legal implications of developing and operating a satellite power system

A number of political and legal implications of developing and operating a satellite power system (SPS) are identified and studied in this report. These include the vulnerability of SPS to actions of adversaries, communications impacts, the legality of an SPS in orbit including on-orbit military protection, alleviation of political concerns about deployment and operation of SPS, programmatic planning for SPS and the interaction of SPS with federal regulatory agencies and major departments. In comparing SPS to terrestrial power stations, it is seen that the political problems are neither clearly larger nor clearly smaller--they are clearly different and they are international in nature. If SPS is to become a reality these problems must be dealt with. Five major issues are identified. These must be resolved in order to obtain international acceptance of SPS. However, this study has found no insurmountable obstacles that would clearly prohibit the deployment, operation and protection of an SPS fleet.

Hazelrigg, G. A., Jr.↗

Risk Trade-Space Analysis for Safe Human Expeditions to Mars

We assessed the integrated safety, health, and performance risk to crews on long-duration missions, specifically to Mars. Using a systems approach rather than one focused on individual countermeasures, we examined the trade space around several such risks to identify high-potential risk mitigation strategies and characterize aspects of Mars mission architectures that could lower aggregated risk. Current Mars Design Reference missions would require durations well over two years and would increase crew exposure to radiation and microgravity well beyond ISS levels, likely resulting in significantly reduced performance beyond our current capability to mitigate that could jeopardize mission success. A “fast Mars transit” round-trip mission concept was studied using an innovative flight dynamics approach to quantify the minimum total mission energy required for a Mars transit with total mission duration less than 400 days. This approach holds promise for sending humans to Mars and returning them safely with acceptable, potentially mitigatable, exposure to microgravity and radiation using current or near-term technologies. The fast transit concept would also result in fewer time-driven vehicle failures and enable sustainable deployment of humans and infrastructure to Mars on a regular cadence, allowing steady exploration and colonization of Mars. Finally, we conclude that reliance on the Low Earth Orbit (LEO) mission operations paradigm – i.e., one of near-complete real-time dependence on experts at Mission Control to manage the combined state of the mission, vehicle, and crew – is high risk given the communication delays and limited resupply of any Mars mission, and this risk is not eliminated by the shorter missions durations of fast transit scenarios. Based on historical trends, it is highly likely that the crew will face a high-consequence problem of uncertain origin during Mars transit when ground support will be greatly reduced. While it may be possible to reduce anomaly rates through improved reliability analysis and testing, and to reduce anomaly impacts through added robustness, such mitigations address only known failure modes and known uncertainties. Therefore, a radical shift in the Human-Systems Integration Architecture (HSIA) that defines the operational paradigm, systems design, and human-systems interactions is required to improve the risk posture to an acceptable level regardless of mission duration.

Mars↗

NASA's management concept for the Space Shuttle Program.

An overview of the Shuttle Program organization and management concepts suggests the necessity of careful measurements of contractor schedules, cost and technical performance, and program modification control to keep both the development and operating cost of the Program at the lowest possible level. Maximum use of the contractors' own management systems and the utilization of new technologies, procedures and materials during space operations are also envisaged as contributors to the reduction of costs per flight to acceptable limits.

Myers, D. D.↗

Touch sensors and control.

Description of the equipment employed and results obtained in experiments with tactile feedback and different levels of automatic control. In the experiments described tactile feedback was investigated by incorporating a touch sensing and touch display system into a teleoperator, while the levels of automatic control were investigated by incorporating supervisory control features in the teleoperator control system. In particular, a hand contact system which senses and reproduces to the operator the contact between the end-effector and the object being touched or manipulated is described, as well as a jaw contact system which senses and reproduces to the operator the shape and location of the object held in the remote jaws, and an arm control system consisting of a control station where the operator controls the motion of the arm by transmitting commands, a remote station that accepts the commands and uses them, and a communications link that limits information flow. In addition, an algorithmic language for remote manipulation is described, and the desired features that an automatic arm controller should possess are reviewed.

Hill, J. W.↗

Skylab mission planning support through the use of a hybrid simulation

The manner in which a hybrid simulation was used in support of Skylab operations in the area of dynamics and control is described. Simulation results were used in the development of acceptable vehicle maneuvers and in the verification of acceptability when the maneuvers were integrated into daily flight plans. The criterion of acceptability was based on vehicle controllability and the minimization of thruster system propellant usage. A simulation of a representative daily flight plan containing three experimental maneuvers is included, along with thruster attitude control system propellant usage tables which show predicted and actual usage for each mission. The inherent characteristics of quick turnaround and flexibility afforded by the hybrid computer proved invaluable in the operations support required throughout the Skylab mission.

Hammer, M. W.↗

Real time flight simulation methodology

An example sensitivity study is presented to demonstrate how a digital autopilot designer could make a decision on minimum sampling rate for computer specification. It consists of comparing the simulated step response of an existing analog autopilot and its associated aircraft dynamics to the digital version operating at various sampling frequencies and specifying a sampling frequency that results in an acceptable change in relative stability. In general, the zero order hold introduces phase lag which will increase overshoot and settling time. It should be noted that this solution is for substituting a digital autopilot for a continuous autopilot. A complete redesign could result in results which more closely resemble the continuous results or which conform better to original design goals.

Parrish, E. A.↗

Laser balancing demonstration on a high-speed flexible rotor

This paper describes a flexible rotor system used for two-plane laser balancing and an experimental demonstration of the laser material removal method for balancing. A laboratory test rotor was modified to accept balancing corrections using a laser metal removal method while the rotor is at operating speed. The laser setup hardware required to balance the rotor using two correction planes is described. The test rig optical configuration and a neodymium glass laser were assembled and calibrated for material removal rates. Rotor amplitudes before and after balancing, trial and correction weights, rotor speed during operation of laser, and balancing time were documented. The rotor was balanced through the first bending critical speed using the laser material removal procedure to apply trial weights and correction weights without stopping the rotor.

Demuth, R. S.↗

Control algorithms and computer simulation of a stand-alone photovoltaic village power system

At Stand-Alone Photovoltaic (SAPV) power systems increase in size and load diversity, the design and simulation of control subsystems takes on added importance. These SAPV systems represent 'mini utilities' with commensurate controls requirements, albeit with the added complexity of the energy source (sunlight received) being an uncontrollable variable. This paper briefly describes a stand-alone photovoltaic power/load system computerized simulation model. The model was tested against operational data from the Schuchuli stand-alone village photovoltaic system and has achieved acceptable levels of simulation accuracy. The model can be used to simulate system designs although with probable battery modification.

Groumpos, P. P.↗

VLSI Reed Solomon decoder design

A Reed Solomon code is a highly efficient error correcting code that NASA will use in future space communication missions. A VLSI implementation of the decoder is presented that accepts data rates of 80 Mbits/second. A total of seven chips are needed and operate with the symbol clock being the system clock for the chip set. Approximately 1.65 billion Galois Field operations per second are achieved with this chip set.

Maki, Gary K.↗

US domestic and international regulatory issues

The U.S. domestic and international regulatory and policy milestones since 1982, when NASA filed its petition with the Federal Communications Commission (FCC) to establish the U.S. domestic Mobile Satellite Service (MSS), are described. In 1985, the FCC proposed to establish MSS services and allocate spectrum for such service. In 1986, the FCC allocated L-band spectrum for MSS. In 1987, at the Mobile World Administrative Radio Conference (MOB WARC-87), despite U.S., Canadian, and Mexican efforts, the WARC did not adopt a multi-service, generic MSS allocation. In 1989, the FCC licensed the first MSS system. After two decisions by the U.S. Court of Appeals, the FCC's licensing actions remain intact. The FCC also has permitted Comsat to provide international aeronautical and land MSS via the Inmarsat system. Inmarsat, however, may not serve the domestic U.S. market. In 1991, the FCC accepted applications for MSS systems, most of which were non-geostationary proposals, for operation in the Radiodetermination Satellite Service (RDSS) bands, and the VHF and UHF bands. In 1992, the FCC proposed rules for non-geostationary MSS systems and applied a negotiated rulemaking procedure to each. Also in 1992, the U.S. position for flexibility in existing MSS bands and for additional worldwide MSS allocations was adopted in large part at the 1992 World Administrative Radio Conference (WARC-92).

Levin, Lon C.↗

Noise Analysis of Spatial Phase coding in analog Acoustooptic Processors

Optical beams can carry information in their amplitude and phase; however, optical analog numerical calculators such as an optical matrix processor use incoherent light to achieve linear operation. Thus, the phase information is lost and only the magnitude can be used. This limits such processors to the representation of positive real numbers. Many systems have been devised to overcome this deficit through the use of digital number representations, but they all operate at a greatly reduced efficiency in contrast to analog systems. The most widely accepted method to achieve sign coding in analog optical systems has been the use of an offset for the zero level. Unfortunately, this results in increased noise sensitivity for small numbers. In this paper, we examine the use of spatially coherent sign coding in acoustooptical processors, a method first developed for digital calculations by D. V. Tigin. This coding technique uses spatial coherence for the representation of signed numbers, while temporal incoherence allows for linear analog processing of the optical information. We show how spatial phase coding reduces noise sensitivity for signed analog calculations.

Gary, Charles K.↗

An Orifice Pulse Tube Cooler for CMOS Computer Cooling

The subject orifice pulse tube cooler employs dual opposed compressor pistons, clearance seals, moving coil linear motors, and flexible bearings cooling capacity is 100 watts at 200 K. A matrix of optimizations explored load temperatures and cooling capacities of 50 K, 100 K, 200 K, 1 watt, 10 watts, and 100 watts. The optimization process resulted in a design with zero second entrance flow and a non-resonant pulse tube. Topics include performance results, mechanical design, and development problems and solutions. The development seeks to use orifice pulse tube mechanical simplicity to achieve a computer cooler with acceptable efficiency, low materials cost, low labor cost, long life, high reliability, low vibration, operation at the standard 60 Hz U.S. grid frequency, and control through simple drive and control electronics.

Riggle, P.↗

Fiber Optic Repair and Maintainability (FORM) Program Progresses

Advanced aircraft will employ fiber-optic interconnection components to transmit information from airframe and propulsion sensors to the flight control computers. Although these optical interconnects have been rigorously tested under laboratory conditions to determine their operating and environmental limits, there is concern as to their repairability and maintainability when placed in actual service. The Fiber Optic Repair and Maintainability (FORM) flight test program will provide data to enable designers to improve these fiber-optic interconnection systems for the next generation of aircraft. FORM is identifying critical problems in installing, maintaining, testing, and repairing fiber-optic interconnection systems in an operational avionics environment. This program is a cooperative Government/industry effort to evaluate optical component acceptability and installation techniques for aircraft.

Source record↗

InGaAsP Avalanche Photodetectors for Non-Gated 1.06 micrometer Photon-Counting Receivers

The efficient detection of single photons at 1.06 micron is of considerable interest for lidar/ladar systems designed for remote sensing an d ranging as well as for free-space optical transmission in photon-st arved applications. However, silicon-based single photon avalanche diodes (SPADs) used at shorter wavelengths have very low single photon d etection efficiency (approximately 1 - 2%) at 1.06 micron, and InP/In GaAs SPADs designed for telecommunications wavelengths near 1.5 micro n exhibit high dark count rates that generally inhibit non-gated (free-running) operation. To bridge this "single photon detection gap" for wavelengths just beyond 1 micron, we have developed high performance , large area (80 - 200 micron diameter) InP-based InGaAsP quaternary absorber SPADs optimized for operation at 1.06 micron and based on a highly reliable planar geometry avalanche photodiode structure. We wil l show that dark count rates are sufficiently low to allow for non-ga ted operation while achieving detection efficiencies far surpassing t hose found for Si SPADs. At a detection efficiency of 10%, 80 micron diameter devices exhibit dark count rates below 1000 Hz and count rate s of at least 3 MHz when operated at -40 C. Significantly higher dete ction efficiencies (30 - 50%) are achievable with acceptable tradeoff s in dark count rate. In this paper, we will also discuss performance modeling for these devices and compare their behavior with longer wav elength InP-based InGaAs ternary absorber SPADs fabricated on a relat ed device design platform.

Itzler, Mark A.↗