Search NASA⌕ Search

SEARCH · Search NASA

Results for “Conversion”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 685 records · Page 38
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

Conversion of cardiac performance data in analog form for digital computer entry

A system is presented which will reduce analog cardiac performance data and convert the results to digital form for direct entry into a commercial time-shared computer. Circuits are discussed which perform the measurement and digital conversion of instantaneous systolic and diastolic parameters from the analog blood pressure waveform. Digital averaging over a selected number of heart cycles is performed on these measurements, as well as those of flow and heart rate. The determination of average cardiac output and peripheral resistance, including trends, is the end result after processing by digital computer.

Miller, R. L.↗
NASA NTRS1972

An analog-to-digital conversion system with a logarithmic characteristic

Detailed analysis of an analog-to-digital conversion system consisting of a linear converter and a logarithmic amplifier containing nonlinear elements. It is shown that the small-signal resolution of such a system is much greater than that of linear systems used under the same conditions. A design for a low-power analog-to-digital converter operating at medium speed with a large input signal variation field is outlined.

Bellomo, A.↗
NASA NTRS1972

One-stage model for color conversion.

Description of a one-stage approximation to the color-conversion model of Richards and Parks (1971). The modified model proposes three channels for color vision, each with different center-surround sensitivities. In its strongest form, the model predicts that the gain-setting control that alters the sensitivities of each channel is solely a function of achromatic contrast.

Richards, W.↗
NASA NTRS1973

Motor starting a Brayton cycle power conversion system using a static inverter

The power conversion module of a 2- to 15-kWe Brayton engine was motor started using a three-phase, 400-hertz static inverter as the power source. Motor-static tests were conducted for initial gas loop pressures of 10, 14, and 17 N/sq cm (15, 20, and 25 psia) over a range of initial turbine inlet temperatures from 366 to 550 K (200 to 530 F). The data are presented to show the effects of temperature and pressure on the motor-start characteristics of the rotating unit. Electrical characteristics during motoring are also discussed.

Curreri, J. S.↗
NASA NTRS1973

Performance of electrical subsystem of 2- to 15-kilowatt Brayton power conversion system

The electrical subsystem of the 2-to 15-kilowatt Brayton power conversion system was evaluated under various operating and off-design temperature conditions in a vacuum environment. Overall operation was satisfactory. Speed controller operation is a major cause of distortion in the system ac voltage and current waveforms. This distortion has a small, but potentially significant effect on the performance of individual subsystem components.

Secunde, R. R.↗
NASA NTRS1973

Conversational high resolution mass spectrographic data reduction

A FORTRAN 4 program is described which reduces the data obtained from a high resolution mass spectrograph. The program (1) calculates an accurate mass for each line on the photoplate, and (2) assigns elemental compositions to each accurate mass. The program is intended for use in a time-shared computing environment and makes use of the conversational aspects of time-sharing operating systems.

Romiez, M. P.↗
NASA NTRS1972

Evaluation testing of a closed Brayton-cycle electrical-power-conversion system.

Description of the design and testing of a recuperated, closed Brayton-cycle, electrical power conversion system designated the Brayton Cycle Demonstrator (BCD). The system uses electrical heaters as a heat source, argon as the cycle working fluid, and gas-lubricated foil-type bearings. Objectives of the test program include (1) evaluation of the overall system performance characteristics and influences on spacecraft integration, (2) familiarization of personnel with operational methods, and (3) determination of system flexibility by operating at a number of off-design conditions. Results obtained to date are discussed.

Redding, T. E.↗
NASA NTRS1974

Digital computer study of nuclear reactor thermal transients during startup of 60-kWe Brayton power conversion system

A digital computer study was made of reactor thermal transients during startup of the Brayton power conversion loop of a 60-kWe reactor Brayton power system. A startup procedure requiring the least Brayton system complication was tried first; this procedure caused violations of design limits on key reactor variables. Several modifications of this procedure were then found which caused no design limit violations. These modifications involved: (1) using a slower rate of increase in gas flow; (2) increasing the initial reactor power level to make the reactor respond faster; and (3) appropriate reactor control drum manipulation during the startup transient.

Jefferies, K. S.↗
NASA NTRS1973

Wind Energy Conversion Systems

Economic feasibilities and energy conversion efficiencies are considered for various alternative energy sources that utilize wind forces.

Savino, Joseph M.↗
NASA NTRS1974

High performance dc-dc conversion with voltage multipliers

The voltage multipliers using capacitors and diodes first developed by Cockcroft and Walton in 1932 were reexamined in terms of state of the art fast switching transistors and diodes, and high energy density capacitors. Because of component improvements, the voltage multiplier, used without a transformer, now appears superior in weight to systems now in use for dc-dc conversion. An experimental 100-watt 1000-volt dc-dc converter operating at 100 kHz was built, with a component weight of about 1 kg/kW. Calculated and measured values of output voltage and efficiency agreed within experimental error.

Harrigill, W. T.↗
NASA NTRS1974

Mode conversion in periodically disturbed thin-film waveguides

Mode conversion in a periodically perturbed thin-film optical waveguide is studied in detail. Three different types of perturbations are considered: periodic index of refraction of the film, periodic index of refraction of the substrate, and periodic boundary. The applications in filters, mode converters, and distributed feedback lasers are discussed.

Elachi, C.↗
NASA NTRS1974

Dynamic conversion of solar generated heat to electricity

The effort undertaken during this program led to the selection of the water-superheated steam (850 psig/900 F) crescent central receiver as the preferred concept from among 11 candidate systems across the technological spectrum of the dynamic conversion of solar generated heat to electricity. The solar power plant designs were investigated in the range of plant capacities from 100 to 1000 Mw(e). The investigations considered the impacts of plant size, collector design, feed-water temperature ratio, heat rejection equipment, ground cover, and location on solar power technical and economic feasibility. For the distributed receiver systems, the optimization studies showed that plant capacities less than 100 Mw(e) may be best. Although the size of central receiver concepts was not parametrically investigated, all indications are that the optimal plant capacity for central receiver systems will be in the range from 50 to 200 Mw(e). Solar thermal power plant site selection criteria and methodology were also established and used to evaluate potentially suitable sites. The result of this effort was to identify a site south of Inyokern, California, as typically suitable for a solar thermal power plant. The criteria used in the selection process included insolation and climatological characteristics, topography, and seismic history as well as water availability.

Powell, J. C.↗
NASA NTRS1974

Measurements of positive ion conversion and removal reactions relating to the Jovian ionosphere

Measured rates are presented for the reaction of He(+) ions with H2 (and D2) molecules to form H(+), H2(+), and HeH(+) ions, as well as for the subsequent reactions of H(+) and HeH(+) ions with H2 to form H3(+). The neutralization of H3(+) /and H5(+)/ ions by dissociative recombination with electrons is shown to be fast. The reaction He(+) + H2 is slow (k 1.1 x 10 to the minus 13th cu cm/sec at 300 K) and produces principally H(+) by the dissociative charge transfer branch. It is concluded that there may be a serious bottleneck in the conversion of two of the primary ions of the upper Jovian ionosphere, H(+) and He(+) (which recombine slowly), to the rapidly recombining H3(+) ion.

Johnsen, R.↗
NASA NTRS1975

Conversion of laser energy to gas kinetic energy

Techniques for the gas phase absorption of laser radiation for conversion to gas kinetic energy are discussed. Absorption by inverse Bremsstrahlung, in which laser energy is converted at a gas kinetic rate in a spectrally continuous process, is briefly described, and absorption by molecular vibrational rotation bands is discussed at length. High pressure absorption is proposed as a means of minimizing gas bleaching and dissociation, the major disadvantages of the molecular absorption process. A band model is presented for predicting the molecular absorption spectra in the high pressure absorption region and is applied to the CO molecule. Use of a rare gas seeded with Fe(CO)5 for converting vibrational modes to translation modes is described.

Caledonia, G. E.↗
NASA NTRS1975

Electrodes for thermionic energy conversion

Problems concerning an application of thermionic energy conversion methods are related to the high heat source temperatures currently required for practical power densities and efficiencies. A description is given of advances made in the development of improved emitter and collector surfaces as a basis for the reduction of operating temperatures. The controlled addition of oxygen has resulted in a considerable improvement of emitter performance. Improvements in converter performance have been obtained by a reduction of the collector work function. Attention is given to fundamental studies, simulated converter environment tests, and variable spacing converter experiments.

Rufeh, F.↗