Optimal desaturation of momentum exchange control systems
Optimal momentum exchange desaturation in attitude control systems for orbiting spacecraft, concerning gravity gradient and disturbance torques
Johnson, C. D.↗
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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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Numerical coefficient of the first exchange inhomogeneity term
First exchange energy inhomogeneity term numerical coefficient approximate derivation
Smith, J. R.↗
Nonadiabatic atom-atom collisions - Two-state impact-parameter calculation of the H/1s/ plus H/1s/ equals H/1s/ plus H/2s/ cross section including electron exchange
Nonadiabatic H-H collisions cross sections in two state time dependent impact parameter approximation, including electron exchange
Ritchie, B.↗
Impact-parameter treatment of hydrogen-hydrogen excitation collisions. III - Electron exchange and nuclear symmetry effects
Electron exchange and nuclear symmetry for 2s and 2p collisional excitations of hydrogen by H atom based on symmetrized atomic orbitals set
Bottcher, C.↗
Gas exchange when one lung region inspires from another
Pulmonary gas exchange studied in computer models with series inequality of ventilation
West, J. B.↗
Nonisotropic exchange coefficients in turbulent swirling flames from mean value distributions
Turbulent swirling flames nonisotropic exchange coefficients determination from time mean velocity, pressure, temperature and concentration distributions
Chigier, N. A.↗
Shock-tube measurements of the vibration- vibration energy exchange probability for the CO-N2 system
Shock tube measurements of vibration-vibration energy exchange probability in nitrogen-carbon monoxide-argon mixtures
Appleton, J. P.↗
A control policy for systems with momentum exchange controllers
Spacecraft pointing control system with momentum exchange controllers, considering near optimal control policy for control moment gyro system
Skelton, R. E.↗
Effect of stratified inequality of blood flow on gas exchange in liquid-filled lungs.
This investigation set out to answer two questions: (1) are the distal alveoli in the terminal lung units less well perfused than the proximal alveoli, i.e., is there stratification of blood flow; and (2) if so, does this enhance gas exchange in the presence of stratified inequality of ventilation. Excised dog lungs were ventilated with saline and perfused with blood. Following single inspirations of xenon 133 in saline and various periods of breath holding, the expired xenon concentration against volume was measured and it confirmed marked stratified inequality of ventilation under these conditions. By measuring the rate of depletion of xenon from alveoli during a period of blood flow, we showed that the alveoli which emptied at the end of expiration had 16% less blood flow than those exhaling earlier. However, by measuring the xenon concentration in pulmonary venous blood, we found that about 10% less tracer was transferred from the alveoli into the blood when the inspired xenon was stratified within the respiratory zone. Thus while stratification of blood flow was confirmed, it was shown to impair rather than enhance the efficiency of gas transfer.
West, J. B.↗
The Gas Exchange Experiment for life detection - The Viking Mars Lander.
The Gas Exchange Experiment of the Viking mission accepts a sample of Martian soil, incubates this soil with nutrient medium, and periodically samples the enclosed atmosphere over this soil for the gases H2, N2, O2, Kr, and CO2. These gases are analyzed by an automated gas chromatograph, and the data are transmitted to earth. The design of the experiment and the qualitative and quantitative changes, if any, of gas composition should allow conclusions to be made on the presence of life on Mars. Data and theory substantiating this approach are presented.
Oyama, V. I.↗
Dynamics of the molecular and atomic mechanisms for the hydrogen-iodine exchange reaction.
The molecular and atomic mechanisms for the hydrogen-iodine exchange reaction are treated theoretically by means of extensive classical trajectories calculated on a reasonable potential energy surface on which the single adjustable parameter is the iodine-core effective charge. The analysis shows the molecular mechanism to be dynamically forbidden, but gives an over-all rate constant for the atomic mechanism that is in agreement with the experimental values. It is indicated that the formation of a weak H2I complex plays an important dynamical role if the atomic mechanism is limited to reactions with collision complexes involving no more than two hydrogen atoms and two iodine atoms. Excellent agreement with experiment is obtained for the rate constant for the recombination I+I+H2 yields I2+H2 and its negative temperature coefficient.
Raff, L. M.↗
Analysis and test of a breadboard cryogenic hydrogen/Freon heat exchanger
System studies required to verify a tube-in-tube cryogenic heat exchanger as optimum for the space shuttle mission are described. Design of the optimum configuration, which could be fabricated from commercially available hardware, is discussed. Finally, testing of the proposed configuration with supercritical hydrogen and Freon 21 is discussed and results are compared with thermal and dynamic analysis.
Desjardins, L. F.↗
The gas exchange of hydrogen-adapted algae as followed by mass spectrometry.
The combination of a mass spectrometer inlet and an oxygen electrode in the same vessel permitted continuous recording of the gas exchange of hydrogenase-containing anaerobically adapted algae. In contrast to conventional manometry, the present method made it possible to discern the simultaneous course of reactions involving O2, CO2, and H2. The experiments strongly support the idea of a balance between the photoproduction and photoutilization of H2.
Stuart, T. S.↗
Ion momentum and energy transfer rates for charge exchange collisions
The rates of momentum and energy transfer have been obtained for charge exchange collisions between ion and neutral gases having arbitrary Maxwellian temperatures and bulk transport velocities. The results are directly applicable to the F-region of the ionosphere where 0+ - 0 charge is the dominant mechanism affecting ion momentum and energy transfer.
Horwitz, J.↗
Respiratory gas exchange of high altitude adapted chick embryos
Study of gas exchange by embryos from chickens acclimatized to an altitude of 3800 m. The oxygen partial pressure and carbon dioxide partial pressure differences across the egg shell were measured and found to be less than the values previously reported for sea-level eggs by about a factor of two. Further measurements of embryonic oxygen consumption and shell conductivity to oxygen indicated that, compared to eggs at sea level, oxygen consumption was reduced by a factor of 0.58 while conductivity to oxygen was increased only by a factor of 1.07 in the high-altitude eggs. These independent measurements predict the change in oxygen partial pressure across the egg shell of the high-altitude eggs to be only 0.54 times that of sea-level eggs; the directly measured factor was 0.53. The authors conclude that at high altitude, a major adaptation of the chick embryo is a reduced metabolism which decreases the change in oxygen partial pressure across the egg shell since its gas conductivity remains essentially unchanged.
Wangensteen, O. D.↗
Gas exchange and the coagulation system of the blood during the effect on the body of high concentrations of oxygen and carbon dioxide
Maximum permissible concentrations of oxygen and carbon dioxide in a controlled atmosphere were determined by evaluating their effects on human gas exchange, blood coagulation, and tolerances to acute hypoxia, acceleration, and physical loads. It was found that functional disturbances depend on the concentration of respiratory gases and the length of stay in an altered atmosphere. By changing the atmospheric composition and by bringing the gaseous environment into accordance with the work and rest regimen and energy expenditures, the general reactivity of the body changes favorably.
Palosh, L.↗
Space shuttle launch vehicle performance trajectory, exchange ratios, and dispersion analysis
A baseline space shuttle performance trajectory for Mission 3A launched from WTR has been generated. Design constraints of maximum dynamic pressure, longitudinal acceleration, and delivered payload were satisfied. Payload exchange ratios are presented with explanation on use. Design envelopes of dynamic pressure, SRB staging point, aerodynamic heating and flight performance reserves are calculated and included.
Toelle, R. G.↗
Frontiers in propulsion research: Laser, matter-antimatter, excited helium, energy exchange thermonuclear fusion
Concepts are described that presently appear to have the potential for propulsion applications in the post-1990 era of space technology. The studies are still in progress, and only the current status of investigation is presented. The topics for possible propulsion application are lasers, nuclear fusion, matter-antimatter annihilation, electronically excited helium, energy exchange through the interaction of various fields, laser propagation, and thermonuclear fusion technology.
Papailiou, D. D.↗