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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 1,045 records · Page 58
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Equations of motion of the lunar roving vehicle.

Equations of motion have been formulated for a four-wheel vehicle as it traverses a terrain characterized by slopes, craters, bumps, washboards, or a power spectrum. Independent suspension and electric motor propulsion are considered. These equations were programmed on the UNIVAC 1108 digital computer. Results are given for the steerability of the Lunar Roving Vehicle (LRV) which was found to be satisfactory for normal operating speeds and turning radii. The vehicle was also found to be satisfactory against overturning in both the pitch and roll mode, and results are presented for various speeds as the LRV engages a bump on meter in diameter and of varying heights. Speed, power consumption, and load characteristics are presented for the LRV traversing a simulated lunar soil at full throttle. Comparisons are given against data compiled from the Apollo 15 mission.

Kaufman, S.↗
NASA NTRS1973

Effect of suspension-line viscous damping on parachute opening load amplification.

A digital computer program was used to investigate the effects of suspension-line viscous damping on the opening loads of a high-altitude parachute system having a specified configuration. It was found (1) that the nonlinear elastic characteristics of the suspension system produce an amplification of the opening load when the viscous damping is negligible, (2) that the load amplification is markedly reduced when the suspension-line viscous damping coefficient is increased, and (3) that the suspension-line viscous damping is an important parameter of opening load amplification for high-velocity parachute inflations.

Poole, L. R.↗
NASA NTRS1972

High-Q toroidal cavities for high frequency klystrons.

A toroidal cavity developed for a 4-KW 12 GHz satellite-borne television transmitter klystron is described. The cavity has an internal Q 40% higher than that of a conventional cylindrical doubly reentrant cavity, thus yielding higher circuit efficiency and conserving energy which cannot be recovered in multistage depressed potential beam collectors. As a result of optimization studies with a digital computer program for obtaining cavity field distributions by a relaxation method and for computing the intrinsic cavity parameters, a particular cavity configuration with conical reentrant tunnel tips and toroidal walls is shown to provide good thermal characteristics and mechanical rigidity as well as low internal losses.

Branch, G. M.↗
NASA NTRS1973

A sequence solution to the Fokker-Planck equation.

In this paper a new approach to nonlinear system analysis based on the Fokker-Planck equation is developed. The development begins as a modification of the parametrix method of partial differential equation theory and provides a sequence solution to the multidimensional time-varying Fokker-Planck equation. This sequence is simplified for the case where only a steady-state solution or a solution for the variance of a particular combination of states is desired. Equations are presented in a form suitable for obtaining numerical results using a digital computer.

Mayfield, W. W.↗
NASA NTRS1972

Coronary flow and left ventricular function during environmental stress.

A canine model was used to study the effects of different environmental stresses on the heart and coronary circulation. The heart was surgically instrumented to measure coronary blood flow, left ventricular pressure, and other cardiovascular variables. Coronary flow was recorded by telemetry. Physiologic data were processed and analyzed by analog and digital computers. By these methods the physiologic response to altitude hypoxia, carbon monoxide, hypercapnia, acceleration, exercise, and the interaction of altitude hypoxia and carbon monoxide were described. The effects of some of these stresses on the heart and coronary circulation are discussed.

Erickson, H. H.↗
NASA NTRS1973

Solution of quadratic matrix equations for free vibration analysis of structures.

An efficient digital computer procedure and the related numerical algorithm are presented herein for the solution of quadratic matrix equations associated with free vibration analysis of structures. Such a procedure enables accurate and economical analysis of natural frequencies and associated modes of discretized structures. The numerically stable algorithm is based on the Sturm sequence method, which fully exploits the banded form of associated stiffness and mass matrices. The related computer program written in FORTRAN V for the JPL UNIVAC 1108 computer proves to be substantially more accurate and economical than other existing procedures of such analysis. Numerical examples are presented for two structures - a cantilever beam and a semicircular arch.

Gupta, K. K.↗
NASA NTRS1973

Analysis of swimming motions.

This paper presents an analysis of swimming motion with specific attention given to the flutter kick, the breast-stroke kick, and the breast stroke. The analysis is completely theoretical. It employs a mathematical model of the human body consisting of frustrums of elliptical cones. Dynamical equations are written for this model including both viscous and inertia forces. These equations are then applied with approximated swimming strokes and solved numerically using a digital computer. The procedure is to specify the input of the swimming motion. The computer solution then provides the output displacement, velocity, and rotation or body roll of the swimmer.

Gallenstein, J.↗
NASA NTRS1973

Nuclear Science Symposium, 19th, and Nuclear Power Systems Symposium, 4th, Miami, Fla., December 6-8, 1972, Proceedings.

Major topics covered include radiation monitoring instrumentation, nuclear circuits and systems, biomedical applications of nuclear radiation in diagnosis and therapy, plasma research for fusion power, reactor control and instrumentation, nuclear power standards, and applications of digital computers in nuclear power plants. Systems and devices for space applications are described, including the Apollo alpha spectrometer, a position sensitive detection system for UV and X-ray photons, a 4500-volt electron multiplier bias supply for satellite use, spark chamber systems, proportional counters, and other devices. Individual items are announced in this issue.

Source record↗
NASA NTRS1973

Digital image processing for information extraction.

The modern digital computer has made practical image processing techniques for handling nonlinear operations in both the geometrical and the intensity domains, various types of nonuniform noise cleanup, and the numerical analysis of pictures. An initial requirement is that a number of anomalies caused by the camera (e.g., geometric distortion, MTF roll-off, vignetting, and nonuniform intensity response) must be taken into account or removed to avoid their interference with the information extraction process. Examples illustrating these operations are discussed along with computer techniques used to emphasize details, perform analyses, classify materials by multivariate analysis, detect temporal differences, and aid in human interpretation of photos.

Billingsley, F. C.↗
NASA NTRS1973

Laminar film condensation on the inside of slender, rotating truncated cones.

A solution for film condensation on the inside of slender rotating truncated cones is established in the region where the half cone angle phi is close to zero and where the equation of Dhir and Lienhard (1971) is no longer valid. All the familiar assumptions used in Nusselt's theory of laminar film condensation are assumed valid, including negligible sub-cooling and momentum changes in the condensate film, no interfacial shear between the condensate and the vapor, and pure conduction within the condensate film. A Runge-Kutta numerical integration method using a digital computer was used. Results for a specific geometry are given for water condensing at 212 F on a condenser wall maintained at 70 F.

Marto, P. J.↗
NASA NTRS1973

Integrated Propulsion Control System program.

Description of a three-year exploratory research program for the design, development, and flight evaluation of an Integrated Propulsion Control System (IPCS). The primary objectives of this program are to establish through flight test the potential improvements in steady-state and transient propulsion system performance that can be achieved as a direct result of new modes of control, more direct sensing of engine and inlet parameters, and the use of more sophisticated, high-speed digital computation. A F-111 E aircraft with the left inlet and engine modified to the IPCS configuration will be used to conduct the flight evaluation.

Bentz, C. E.↗
NASA NTRS1973

Use of the single-breath method of estimating cardiac output during exercise-stress testing.

The single-breath cardiac output measurement technique of Kim et al. (1966) has been modified for use in obtaining cardiac output measurements during exercise-stress tests on Apollo astronauts. The modifications involve the use of a respiratory mass spectrometer for data acquisition and a digital computer program for data analysis. The variation of the modified method for triplicate steady-state cardiac output measurements was plus or minus 1 liter/min. The combined physiological and methodological variation seen during a set of three exercise tests on a series of subjects was 1 to 2.5 liter/min. Comparison of the modified method with the direct Fick technique showed that although the single-breath values were consistently low, the scatter of data was small and the correlation between the two methods was high. Possible reasons for the low single-breath cardiac output values are discussed.

Buderer, M. C.↗
NASA NTRS1973

Competitive evaluation of failure detection algorithms for strapdown redundant inertial instruments.

Seven algorithms for failure detection, isolation, and correction of strapdown inertial instruments in the dodecahedron configuration are competitively evaluated by means of a digital computer simulation that provides them with identical inputs. Their performance is compared in terms of orientation errors and computer burden. The analytical foundations of the algorithms are presented. The features that are found to contribute to superior performance are use of a definite logical structure, elimination of interaction between failures, different thresholds for first and second failures, use of the 'parity' test signals, and avoidance of iteration loops.

Wilcox, J. C.↗
NASA NTRS1973

SAFE - Six axis frequency evaluation of a motion simulator.

SAFE is a digital computer program used to check the response of an aircraft motion simulator. SAFE drives each axis of the simulator near its acceleration, velocity and position limits, recording the simulator motions for comparison with nominal responses. SAFE also drives up to six axes at once to measure the frequency response and noise levels of each axis. Together these two measurements provide a sensitive check of the entire motion system, yet they can be completed in less than ten minutes.

Shirley, R. S.↗
NASA NTRS1974

Continuous Fourier transform system

Complex digital computer is not required, only summing amplifiers and attenuators are used for transformation of signal. Continuous transform system may be used for spectrum analysis, filtering, transfer function synthesis, and communications.

Munoz, R. M.↗
NASA NTRS1975

Automated maintenance for complex hybrid systems

Digital computer, Control Computer Subsystem (CCS), possess high degree of fault tolerance. CCS embodies concepts of self-test and repair. It is capable of monitoring its own performance and of identifying and replacing with standby spare any of its units that fail.

Gilley, G. C.↗
NASA NTRS1973

Space shuttle main engine controller assembly, phase C-D

System design and system analysis and simulation are slightly behind schedule, while design verification testing has improved. Input/output circuit design has improved, but digital computer unit (DCU) and mechanical design continue to lag. Part procurement was impacted by delays in printed circuit board, assembly drawing releases. These are the result of problems in generating suitable printed circuit artwork for the very complex and high density multilayer boards.

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