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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 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1976

Feasibility demonstration of a variable frequency driver-microwave transient regression rate measurement system

The feasibility of a system capable of rapidly and directly measuring the low-frequency (motor characteristics length bulk mode) combustion response characteristics of solid propellants has been investigated. The system consists of a variable frequency oscillatory driver device coupled with an improved version of the JPL microwave propellant regression rate measurement system. The ratio of the normalized regression rate and pressure amplitudes and their relative phase are measured as a function of varying pressure level and frequency. Test results with a well-characterized PBAN-AP propellant formulation were found to compare favorably with the results of more conventional stability measurement techniques.

Strand, L. D.↗
NASA NTRS1977

Differential current driver

Three operational amplifiers in closed-loop configuration, form stable current driver for variable non-ground-reference loads. Circuit uses lower-voltage power supplies than other circuits of this type, and provides constant voltage-to-current gain in low noise configuration. Additional reactive elements could offer frequency compensation for complex loads.

Kopp, G. F.↗
NASA NTRS1977

Basic coaxial mass driver construction and testing

A basic coaxial mass driver has been constructed by a group of students to verify performance predictions in the acceleration range envisaged for the first lunar device. The bucket is guided by four copper tubes which also supply direct current excitation for its single aluminum coil, and is accelerated by twenty coaxial coils along a 2 m track, followed by a deceleration section. The coils are individually energized by electrolytic photoflash capacitors triggered by solid state switches on the basis of bucket position.

Fine, K.↗
NASA NTRS1977

Mass-driver reaction engine as Shuttle upper-stage

Optimization has been carried out on the design of a mass-driver intended for upgrading the Shuttle to geosynchronous and lunar-orbit capability. The machine accelerates 2,100 tons/yr of external tankage, in 14-gram segments, to exhaust velocities of 8,000-10,000 m/s. The resulting reaction force raises 1,700 tons/yr. of Shuttle payloads to high orbit, in two round trips. Exhaust velocity and thrust can be optimized for each mission segment. For a mission requiring an exhaust velocity of 8,000 m/sec, thrust is 560 newtons, power is 2.9 megawatts, and efficiency is 75%. Total electrical component mass including power supplies and waste-heat radiators is 89 tons. To insure that reaction mass does not constitute a hazard, segments may be in the form of powder, electrostatically dispersed after acceleration, and/or thrust may be vectored.

Oneill, G. K.↗
NASA NTRS1977

Shuttle's 160 hour ground turnaround - A design driver

Turnaround analysis added a new dimension to the Space Program with the advent of the Space Shuttle. The requirement to turn the flight hardware around in 160 working hours from landing to launch was a significant design driver and a useful tool in forcing the integration of flight and ground systems design to permit an efficient ground operation. Although there was concern that time constraints might increase program costs, the result of the analysis was to minimize facility requirements and simplify operations with resultant cost savings.

Widick, F.↗
NASA NTRS1977

Mass drivers. 1: Electrical design

A mass driver is an electrical device used to accelerate payloads of any material to a high velocity. Small vehicles (called buckets) containing superconducting coils carry the payloads. These buckets are accelerated by pulsed magnetic fields, timed by information on their position, and are guided by induced magnetic fields set up in a surrounding guideway. Upon reaching the correct velocity, the buckets release their payloads, then they are slowed for recirculation to be reused. A rationale is presented that leads to a relatively simple and near-optimum design, as well as basic programs for calculating acceleration. The transverse oscillation frequencies are found to be invariant to guideway transverse dimensions.

William H. Arnold↗
NASA NTRS1979

High-acceleration mass drivers

High-acceleration mass drivers are discussed including the MD2 model of axial geometry, with individually powered drive coils of 13.1 cm diameter. Timing is derived through the interruption of light beams by the moving armature (bucket). Electric power is provided by the resonant discharge of sector capacitor banks through silicon-controlled rectifiers in a two-phase, quadrature circuit. The bucket flies in vacuum, guided by passive dynamic eddy-current magnetic forces, those currents flowing in strip conductors lining the inside of a nonconducting vacuum pipe. Quantitative measurements are obtained with a solid bucket carrying two superconducting coils with a current density of 25 kA/sq cm. A cryogenic station for cooling the bucket to liquid helium temperature is connected to the vacuum pipe.

Oneill, G. K.↗
NASA NTRS1980

Driver gas flow with fluctuations

A shock tube's driver gas can apparently provide flow with turbulent bursts. The fluctuations are interpreted using a boundary layer model of contact surface flow and results form a kinetic theory of turbulence. With this, a lower limit of 4 on the ratio of maximum to minimum turbulent intensities in contact surface instabilities has been estimated.

Johnson, J. A., III↗
NASA NTRS1983

Driver for DISSPLA Plotter

DISPLOT is generalized outside driver for commercially-available DISSPLA (Display Integrated Software System and Plotting Language) plotting system. DISPLOT program provides user with simple-to-use graphics capability with great deal of application flexibility. DISPLOT is independent of whatever program generates data to be plotted. DISPLOT is used for generation of plotter microfilm, microfiche, and terminal plots.

Baldwin, M. L.↗
NASA NTRS1981

Recent developments in mass drivers

In the past eight months a new mass driver concept has been explored through calculation and inductance model verification. It retains the linear synchronous principle and freedom from arcs, plasmas or physical contact between the accelerated bucket and accelerator. However, it discards passive magnetic flight and obtains transverse focussing from strong off-axis restoring forces produced by drive coils operating in a pull-only mode. This paper gives the reasoning on which the new concept is based, and applies the concept to a lunar catapult design.

Oneill, G. K.↗
NASA NTRS1984

A Manual Control Test for the Detection and Deterrence of Impaired Drivers

A brief manual control test and a decision strategy were developed, laboratory tested, and field validated which provide a means for detecting human operator impairment from alcohol or other drugs. The test requires the operator to stabilize progressively unstable controlled element dynamics. Control theory and experimental data verify that the human operator's control ability on this task is constrained by basic cybernetic characteristics, and that task performance is reliably affected by impairment effects on these characteristics. Assessment of human operator control ability is determined by a statistically based decision strategy. The operator is allowed several chances to exceed a preset pass criterion. Procedures are described for setting the pass criterion based on individual ability and a desired unimpaired failure rate. These procedures were field tested with apparatus installed in automobiles that were designed to discourage drunk drivers from operating their vehicles. This test program demonstrated that the control task and detection strategy could be applied in a practical setting to screen human operators for impairment in their basic cybernetic skills.

Stein, A. C.↗
NASA NTRS1984

Sensitivities of projected 1980 photovoltaic system costs to major system cost drivers

The sensitivity of projected 1990 photovoltaic (PV) system costs to major system cost drivers was examined. It includes: (1) module costs and module efficiencies; (2) area related balance of system (BOS) costs; (3) inverter costs and efficiencies; and (4) module marketing and distribution markups and system integration fees. Recent PV system cost experiences and the high costs of electricity from the systems are reviewed. The 1990 system costs are projected for five classes of PV systems, including four ground mounted 5-MWp systems and one residential 5-kWp system. System cost projections are derived by first projecting costs and efficiencies for all subsystems and components. Sensitivity analyses reveal that reductions in module cost and engineering and system integration fees seem to have the greatest potential for contributing to system cost reduction. Although module cost is clearly the prime candidate for fruitful PV research and development activities, engineering and system integration fees seem to be more amenable to reduction through appropriate choice of system size and market strategy. Increases in inverter and module efficiency yield significant benefits, especially for systems with high area related costs.

Zimmerman, L. W.↗
NASA NTRS1986

Levitation With a Single Acoustic Driver

Pair of reports describes acoustic-levitation systems in which only one acoustic resonance mode excited, and only one driver needed. Systems employ levitation chambers of rectangular and cylindrical geometries. Reports first describe single mode concept and indicate which modes used to levitate sample without rotation. Reports then describe systems in which controlled rotation of sample introduced.

Barmatz, M. B.↗
NASA NTRS1990

Voltage-Boosting Driver For Switching Regulator

Driver circuit assures availability of 10- to 15-V gate-to-source voltage needed to turn on n-channel metal oxide/semiconductor field-effect transistor (MOSFET) acting as switch in switching voltage regulator. Includes voltage-boosting circuit efficiently providing gate voltage 10 to 15 V above supply voltage. Contains no exotic parts and does not require additional power supply. Consists of NAND gate and dual voltage booster operating in conjunction with pulse-width modulator part of regulator.

Trump, Ronald C.↗
NASA NTRS1990

The nonlinear response of AE to the IMF Bs driver - A spectral break at 5 hours

The existence of a sharp break in the power spectrum of AE at about 5 hours is demonstrated. Several possible explanations of the nonlinear response of AE to the IMF Bs driver are briefly discussed, including: variable ionospheric conductivity (increasing with Bs) for the high frequency regime, and several AE saturation mechanisms for the low frequency regime.

Tsurutani, Bruce T.↗
NASA NTRS1989

NASA direct detection laser diode driver

TRW has developed a prototype driver circuit for GaAs laser diodes as part of the NASA/Goddard Space Flight Center's Direct Detection Laser Transceiver (DDLT) program. The circuit is designed to drive the laser diode over a range of user-selectable data rates from 1.7 to 220 Mbps, Manchester-encoded, while ensuring compatibility with 8-bit and quaternary pulse position modulation (QPPM) formats for simulating deep space communications. The resulting hybrid circuit has demonstrated 10 to 90 percent rise and fall times of less than 300 ps at peak currents exceeding 100 mA.

Seery, B. D.↗
NASA NTRS1990

A comparison of transportation node costs and their primary drivers

This paper describes the process for defining and evaluating the costs of alternative transportation node concepts for Space Station Freedom. A cost estimating methodology including costs of development, production, delivery, assembly, steady state operations, and mission-specific operations is described in detail. The primary drivers of transportation node costs are identified and discussed.

Comstock, Douglas A.↗
NASA NTRS1991

Pulse-Width-Modulating Driver for Brushless dc Motor

High-current pulse-width-modulating driver for brushless dc motor features optical coupling of timing signals from low-current control circuitry to high-current motor-driving circuitry. Provides high electrical isolation of motor-power supply, helping to prevent fast, high-current motor-driving pulses from being coupled through power supplies into control circuitry, where they interfere with low-current control signals.

Salomon, Phil M.↗