Energy exchange between electron and molecular gases
Energy transfer between electron and molecular gases
Biberman, L. M.↗
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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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An investigation of the optimal conditions of rocket motion in the vicinity of a planet
Optimal control of points of motion for mass transfer in vacuums in gravitational field
Davidson, B. KH.↗
The dispersion equations for multilayer jets and for several jets
Boundary stability, noise formation, and dispersion equation of plane supersonic jet ejector
Sedelnikov, T. KH.↗
Automatic compensation circuit for slow-sweep control of a stroboscopic oscillograph
Operating principle and functional automatic circuit for stroboscopic oscillograph control
Khermanis, E. KH.↗
Radio survey of Markarian galaxies at 6 and 11 cm
One hundred and fifty-one objects from Markarian's lists 6 and 7 were observed at 6 cm with a 3 sigma detection limit of about 30 mJy. Eight Markarian objects were detected, six of which were also observed at 11 cm. Forty-five others were negative at this wavelength. Two of the detections, numbers 533 and 668, are Seyfert galaxies; additionally, UB1 was detected at 6 cm and NGC 7715 and III Zw 2 were found at 11 cm.
Kojoian, G.↗
Ultraviolet photometry from the Orbiting Astronomical Observatory. XXXIX - The structure of the eclipsing Wolf-Rayet binary V444 Cygni as derived from light curves between 2460 A and 3. 5 microns
The WN5 component of V444 Cyg is characterized on the basis of light curves constructed using 1971 OAO observations at 425, 332, 298, and 246 nm and the broadband data at 2.2 and 3.5 microns of Hartmann (1978). Data and calculation results are presented in tables and graphs and discussed. Parameters estimated include core radius 2.9 solar radii, surface temperature 90,000 K, surface electron density 9 x 10 to the 12th/cu cm, surface outflow velocity 400 km/s, and terminal velocity (at about 10 solar radii) 2500 km/s, suggesting that the flow is He. These results are found to agree with the model of Wolf-Rayet atmospheres proposed by Beals (1929, 1944).
Cherepashchuk, A. M.↗
Analysis of ultraviolet atmospheric eclipses in the Wolf-Rayet binary CV Serpentis
While no eclipses deeper than 0.04 mag are noted in the present UV spectra, covering one-half of an orbital cycle of CV Ser, in the electron scattering continuum at 2400-3200 A or in fine error sensor observations, marked atmospheric eclipses of up to 0.5 mag depth are observed in individual strong lines and over large ranges of the continuum at shorter wavelengths. The flux above the continuum in the C II 1247 A, Si IV 1400 A, and Si IV 1723 lines showed similar phase dependence with emission weakening, as well as with the emission's going into absorption as phase progresses from superior to inferior conjunction of the WC star (primary eclipse). These observations show effects very similar to the behavior of WN stars in the UV.
Eaton, J. A.↗
Stratification of the extended atmosphere of the Wolf-Rayet component of V444 Cygni
Ultraviolet spectra covering both eclipses of V444 Cygni have been obtained. Longward of 1570 angstroms, the continuum brightness showed essentially the same variation seen in the optical (at 4244 angstroms). Striking atmospheric eclipses of up to 0.7 mag in depth were detected, however, in individual strong lines as well as over large ranges of the continuum shortward of 1500 angstroms. IUE data are used to estimate the degree of interstellar extinction and terminal expansion velocity of the system and to study the phase dependence of the continuum and line absorptions.
Eaton, J. A.↗
The lower thermosphere wind regime from simultaneous observations over Euroasia (Collm, Dushanbe, Frunze)
The circulation in the lower thermosphere as determined from the results of measurements in 1984 is considered. Ionospheric drift measurements were taken using the method of spaced reception in the long wave range. Other measurements were taken using the D2 method. Average daily values of wind velocity were used. Discontinuity of measurements ranged from a day to a week. Preliminary data were reduced to the common average height of 93 km with the help of vertical profiles of wind velocity components. The results of measurements of zonal and meridional wind velocity components are presented. Zonal circulation changes from westerly to easterly winds were observed in winter, in periods of spring time reversal and during stratomesospheric rises in temperature.
Schminder, R.↗
The use of four-photon Raman spectroscopy for the remote sensing of natural objects
The results of the laboratory simulation of optical Kerr effect/Raman spectroscopy for the purpose of remote sensing are presented. The experimental setup is described, and measurements of the vibrational spectra of various liquids obtained. Attention is paid to the possibility of using the proposed method to detect trace hydrocarbons in water, and the spectrum of petroleum is obtained. Full-scale measurements using a laser spectrometer were made on the Black Sea.
Bunkin, A. F.↗
Changes in the status of the human tibia during antiorthostatic hypokinesia
Changes were studied in biomechanical properties of the human tibia during prolonged antiorthostatic hypokinesia with different modes of motor activity and pharmacotherapy and comparison of results obtained with parallel examinations using ultrasonic diagnosis and photon absorptiometry.
Tatarinov, A. M.↗
An 8-b 1.3-MHz successive-approximation A/D converter
A new successive-approximation A/D converter is described. It combines a string of equal-valued polysilicon resistors and a set of ratioed capacitors in a unique circuit configuration so that a high sampling rate is achieved. The comparator is realized by a chopper-stabilized amplifier to reduce the effect of the offset voltages of MOS amplifiers. The converter performs an 8-b monotonic conversion with a differential nonlinearity less than 1 LSB in 770 nsec. The die area is 3750 sq mil. This new conversion technique can also be utilized in a pipelined A/D converter (Temes, 1985) and enables it to achieve high speed.
Hadidi, KH.↗
Nondestructive measurement of intensity of optical fields using spontaneous parametric down conversion
Results of nondestructive measurements of intensity (photons per mode) of light from different sources are discussed. The procedure of measurement does not destroy the state of the optical field. The method is based on using the second order nonlinearity of crystal media lacking a center of symmetry and the nonclassical properties of the process of Spontaneous Parametric Down Conversion (SPDC).
Penin, A. N.↗
The Galactic center radio source shines below the Compton limit
Absence of refractive scintillation of Sgr A*, the Galactic center radio source, at 1.3 and 0.8 mm wavelengths places an observational limit of brightness temperature of below 0.5 x 10 exp 12 K on the source. This is less than the maximum brightness of an incoherently synchrotron-emitting plasma, 10 exp 12 K, known as the Compton limit. The refractive scintillations expected, due to strong broadening of the source by the interstellar plasma, are observed by Zhao et al. at decimeter wavelengths. It has proven to be impossible to observe them at 1.3 and 0.8 mm wavelengths over time spans between 0.1 s and 24 hr. Such scintillations are quenched by source size greater than about 0.1 AU, or, equivalently, less than 0.5 x 10 exp 12 K for Sgr A*, at 0.8 mm wavelength. The scintilations would also require fluctuations with scale sizes of 0.1 AU in the scattering plasma, moving across the line of sight at velocities above about 100 km/s. The plasma that scatters Sgr A* satisfies the latter two conditions, and the absence of scintillations is due to the size of the source. This observation strengthens the identification of Sgr A* as a quiescent galactic nucleus.
Gwinn, C. R.↗
Bandwidth compression of the digitized HDTV images for transmission via satellites
This paper investigates a subband coding scheme to reduce the transmission bandwidth of the digitized HDTV images. The HDTV signals are decomposed into seven bands. Each band is then independently encoded. The based band is DPCM encoded and the high bands are encoded by using nonuniform Laplacian quantizers with a dead zone. By selecting the dead zone on the basis of energy in the high bands an acceptable image quality is achieved at an average of 45 Mbits/sec (Mbps) rate. This rate is comparable to some very hardware intensive schemes of transform compression or vector quantization proposed in the literature. The subband coding scheme used in this study is considered to be of medium complexity. The 45 Mbps rate is suitable for transmission of HDTV signals via satellites.
Al-Asmari, A. KH.↗
Kinetic treatment of nonlinear magnetized plasma motions - General geometry and parallel waves
The expansion of kinetic equations in the limit of a strong magnetic field is presented. This gives a natural description of the motions of magnetized plasmas, which are slow compared to the particle gyroperiods and gyroradii. Although the approach is 3D, this very general result is used only to focus on the parallel propagation of nonlinear Alfven waves. The derivative nonlinear Schroedinger-like equation is obtained. Two new terms occur compared to earlier treatments, a nonlinear term proportional to the heat flux along the magnetic field line and a higher-order dispersive term. It is shown that kinetic description avoids the singularities occurring in magnetohydrodynamic or multifluid approaches, which correspond to the degenerate case of sound speeds equal to the Alfven speed, and that parallel heat fluxes cannot be neglected, not even in the case of low parallel plasma beta. A truly stationary soliton solution is derived.
Khabibrakhmanov, I. KH.↗
Collisionless parallel shocks
Consideration is given to a collisionless parallel shock based on solitary-type solutions of the modified derivative nonlinear Schroedinger equation (MDNLS) for parallel Alfven waves. The standard derivative nonlinear Schroedinger equation is generalized in order to include the possible anisotropy of the plasma distribution and higher-order Korteweg-de Vies-type dispersion. Stationary solutions of MDNLS are discussed. The anisotropic nature of 'adiabatic' reflections leads to the asymmetric particle distribution in the upstream as well as in the downstream regions of the shock. As a result, nonzero heat flux appears near the front of the shock. It is shown that this causes the stochastic behavior of the nonlinear waves, which can significantly contribute to the shock thermalization.
Khabibrakhmanov, I. KH.↗
The structure of mass-loading shocks
A new two-fluid model which describes mass loading in the solar wind (e.g., the interaction of the solar wind with a cometary coma or the local interstellar medium) is presented. The self-consistent back-reaction of the mass-loaded ions is included through their effective scattering in low-frequency MHD turbulence and the invocation of a diffusive approximation. Such an approximation has the advantage of introducing self-consistent dissipation coefficients into the governing equations, thereby facilitating the investigation of the internal structure of shocks in mass-loading environments. To illustrate the utility of the new model, we consider the structure of cometary shocks in the hypersonic one-dimensional limit, finding that the incoming solar wind is slowed by both mass loading and the development of a large cometary ion pressure gradient. The shock is broadened and smoothed by the cometary ions with a thickness of the order of the cometary ion diffusion scale.
Zank, G. P.↗