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1.
An exact analysis of the effects of mass transfer on the flow of a viscous incompressible fluid past an uniformly accelerated vertical porous and non-porous plate has been presented on taking into account the free convection currents. The results are discussed with the effects of the Grashof number Gr, the modified Grashof number Sc, the Schmidt number Sc, and the suction parametera for Pr (the Prandtl number)=0.71 representating air at 20°C.Nomenclature a suction parameter - C species concentration - C species concentration at the free stream - g acceleration due gravity - Gc modified Grashof number (vg*(C –C )/U 0 3 ) - Pr Prandtl number (C p/K) - T temperature of the fluid near the plate - T dimensionless temperature near the plate ((T-T )/(T -T )) - U(t) dimensionless velocity of the plate (U/U 0) - v normal velocity component - v 0 suction/injection velocity - x, y coordinate along and normal to the plate - v kinematic viscosity (/gr) - C p specific heat at constant pressure - C w species concentration at the plate - C non-dimensional species concentration ((C-C )/(C w -C )) - Gr Grashof number (g(T w -T )/U 0 3 ) - D chemical molecular diffusivity - K thermal conductivity - Sc Schmidt number (/D) - T w temperature of the plate - T free stream temperature - t time variable - t dimensionless time (tU 0 2 /) - U 0 reference velocity - u velocity of the fluid near the plate - u non-dimensional velocity (u/U 0) - v dimensionless velocity (v/U 0) - v 0 non-dimensionalv 0 (v 0 /U0)=–at–1/2 - y dimensionless ordinate (yU 0/) - density of the fluid - coefficient of viscosity  相似文献   

2.
In the theory of supergravity (N=1), the supersymmetric version of general relativity, and for the Kasner cosmological model (Bianchi type I) we find a non-trivial solution (for the metric and spinor-vector) under the most simple assumption =11 + 22; 12+21=0 and for a special choosed gaugeN=1,N j=0, 0=0. This method could be also applied to other cosmological metrics and extended to enlarged Grassmann basis.O. Obregón was partially supported by the Alexander von Humboldt Stiftung.  相似文献   

3.
The Franck-Condon (FC) factors (transition probabilities) andr-centroids have been evaluated by the reliable numerical integration procedure for the bands of the A6+ X 6+ system of astrophysical molecule CrH, using a suitable potential. The dissociation energyD 0 0 = 2.3 eV for the electronic ground state of CrH has been estimated by fitting the Hulburt-Hirschfelder function to the experimental potential energy curve, using the correlation coefficient.  相似文献   

4.
An approximate analytical method of solving the polytropic equilibrium equations, first developed by Seidov and Kuzakhmedov (1978), has been extended and generalized to equilibrium configurations of axisymmetric systems in rigid rotation, with polytropic index,n =n p + n , nearn p =0, 1, and 5. Though the details of the method depend on the value ofn p , acceptable results are obtained for | n | 0.5 to describe slowly rotating configurations in the range 0n1.5, 4.5n5. In the limit of rotational equilibrium configurations, when the distorsion may be large enough, a satisfactory approximation holds only in the range 0n, 1n1.5, 4.5n5.  相似文献   

5.
Morse potential energy curves forC 1+ andC 1+ of AlH have been constructed. The energy values have been found to increase from vibrational levels 0 to 6 and decrease from vibrational levels 7 to 50 with the corresponding centre and half-width in the stateC 1+. InC 1+ state the energy values have been found to increase from vibrational levels 0 to 28 and decrease from vibrational levels 29 to 50 with the corresponding centre and half-width.  相似文献   

6.
Vibrational transition probabilities namely Franck-Condon factors and -centroids have been evaluated using an approximate analytical method for theA-X systems of OH and PN. KKRV potential energy curves forX 2 i ,X 1+,A 2+, andA 1 states of OH and PN have been constructed using the latest spectroscopic data. The value of -centroids for the band have been found to increase linearly with the corresponding wavelengths. We show results for six new bands and OH and eight new bands of PN in the spectra of astronomical objects.  相似文献   

7.
By solving the Euler hydrodynamical equations we have obtained closed form solutions for the angular velocities and pressures of a three stratified non-confocal heterogeneous oblate spheroid. Limiting and particular solutions cases, such as a spheroid with N layers, a stratified spheroid with the same eccentricities, as well as confocal layered spheroids are also explicitly written down. As an application, we have numerically estimated planet Earth's outer and inner cores' ellipticities to be o=1/413.318 and i=1/424.616, respectively. These Earth's ellipticities values are in good agreement with those found in the literature.  相似文献   

8.
Computations of polarization and intensity of radiation from a unit stellar surface area are presented, as well as a study of the numerical characteristics of atmospheres — single-scattering albedo and the initial source function(), which define the polarization behaviour of atmospheres. The radiatively stable models of stellar atmospheres presented by Kuruczet al. (1974) and Kurucz (1979) have been used for calculations. Since the versus optical depth dependence is rather weak, it has been assumed that (=cost. With a fixed effective temperatureT eff maximum values of are characteristic of stars featuring the lowest surface gravity accelerationg. Among stars with radiatively stable atmospheres, maximum values of (=5000 Å) 0.4–0.6 are exhibited by supergiants withT eff=8000–20 000 K. The plot of () is characterized by discontinuities at the boundaries of spectral series for hydrogen and, sometimes, for helium. Maximum are attained in the Lyman region of =912–1200 Å, where can reach the value 0.7–0.9 for supergiants, this value being 0.3 for Main-Sequence stars. For stars withT eff 35 000 K, high values of also are attained for <912 Å. Within the infrared region, is always small because of bremsstrahlung absorption.A rapid growth of the source functionB with < typical for ultraviolet range (within the Wien part of spectrum), together with high values of results in the strong polarization of emission from a unit stellar surface element, sometimes exceeding the values for the case of a pure electron scattering. For longer wavelengths, where the limb-darkening coefficient is smaller, the plane of polarization abruptly turns 90° in the central parts of the visible stellar disk.  相似文献   

9.
Infinite series expansions are obtained for the doubly averaged effects of the Moon and Sun on a high altitude Earth satellite, and the results used to interpret numerically integrated examples. New in this paper are: (1) both sublunar and translunar satellites are considered; (2) analytic expansions include all powers in the satellite and perturbing body semi-major axes; (3) the fact that retrograde orbits have more benign eccentricity behavior than direct orbits should be exploited for high altitude satellite systems; and (4) near circular orbits can be maintained with small expenditures of fuel in the face of an exponential driving force one forI ab, whereI b=180°–I a andI a is somewhat less than 39.2° for sublunar orbits and somewhat greater than 39.2° for translunar orbits.Nomenclature a semi-major axis - A lk coefficient defined in Equation (11) - B lk coefficient defined in Equation (24) - C km coefficient defined in Equation (25) - D, E, F coefficients in Equations (38), (39) - e eccentricity - H k expression defined in Equation (34) - expression defined in Equation (35) - I inclination of satellite orbit on lunar (or solar) ring plane - J 2 coefficient of second harmonic of Earth's gravitational potential (1082.637×10–6 R E 2 ) - K k, Lk, Mk expressions in Section 4 - expressions in Section 4 - p=a(1–e 2) semi-latus rectum - P l Legendre polynomial of degreel - q argument of Legendre polynomial - radial distance of satellite - R E Earth equatorial radius (6378.16 km) - R, S, W perturbing accelerations in the radial, tangential and orbit normal directions - syn synchronous orbit radius (42 164.2 km=6.6107R E) - t time - T satellite orbital period - T orbital period of perturbing body (Moon) - T e period of long periodic oscillations ine for |I|<I a - T s synodic period - U gravitational potential of lunar (or solar) ring - x, y, z Cartesian coordinates of a satellite with (x, y) being the ring plane - coefficient defined in Equation (20) - average change in orbital element over one orbit (=a, e, I, , ) - 1,23 unit vectors in thex, y, z coordinate directions - r , s , w unit vectors in the radial, tangential and orbit normal directions - =+ angle along the orbital plane from the ascending node on the ring plane to the true position of the satellite - angle around the ring - gravitational constant times mass of Earth (3.986 013×105 km s–2) - gravitational constant times mass of Moon (or Sun) - m gravitational constant times mass of Moon (/81.301) - s gravitational constant time mass of Sun (332 946 ) - ratio of the circumference of a circle to its diameter - radius of lunar (or solar) ring - m radius of lunar ring (60.2665R E) - s radius of solar ring (23455R E) - true anomaly - argument of perigee - 0 initial value of - i critical value of in quadranti(i=1, 2, 3, 4) - longitude of ascending node on ring plane This work was sponsored by the Department of the Air Force.  相似文献   

10.
Surface photometry of the UV continuum galaxy NGC 838 has been carried out in theB, V system using photographic plates obtained with the 74 Kottamia telescope, Egypt. Isophotes, luminosity profiles, integrated photographic magnitudes, effective diameters and other photometric parameters are derived.The photoelectrically calibrated total apparent magnitudes areB T =13.57 with maximum diameters 1.57×1.34 (at threshold m =27.7 mag.//) andV T =12.91 with maximum diameters 1.54×1.32 (at threshold m =27.7 mag./). The integrated colour index(B–V) T =0.66 and the effective surface brightness e (B=19.0 mag./) and e (V=19.7 mag./. The major axis is at position angle =85°±1°.The nucleus of NGC 838 is quite blue (integrated colour(B–V)=0.41 forr *<0.1) compared to normal galaxies while the colour becomes redder from the nucleus outwards. The UV excess, H emission and radio continuum emission previously observed from this galaxy by other investigators may be attributed to a recent burst of star formation in the nucleus of the galaxy of duration slightly greater than 2×107 yr.  相似文献   

11.
Apparent radius, visual brightness, effective temperature and absolute radius for 416 B5 v-F5 v stars of the catalogue of the Geneva Observatory (Rufener, 1976) have been determined.Twenty-eight stars, anomalous in log versus (m v)0 diagrams, have been singled out. A good correlation for seven stars, in common with the list of Hanbury Brownet al. (1974), has been found. Similar parameters determined for 279 B5 v-F5 v stars of two preceding papers (Fracassiniet al., 1973, 1975) have allowed us to determine the averaged diagrams logq v/q, logR/R and logT e versus (B-V)0 for 695 B5 v-F5 v stars.Moreover, in the present paper a good correlation logq v/q versus logR/R and careful relation M v=–7.40logR/R +3.31 for B5 v-F5 v stars have been determined. Plain correlations between logR/R and blanketing parameterm 2 for some spectral types seem to point out that there arereal differences in the absolute radii of stars of thesame spectral type, in agreement with recent researches on the HR diagram (Houck and Fesen, 1978).Systematic differences between double (spectroscopic and visual) and single stars are found. In particular, the averaged relation m 2 versus logR/R shows that A2 v-F5 v double stars may have a higher metallicity indexm 2 and smaller absolute radii than single stars. Finally, the diagram logv sini versus logR/R confirms some properties of binary systems found by other researchers (Huang, 1966; Plavec, 1970; Levato, 1974; Kitamura and Kondo, 1978).Thesis for the degree in Applied Physics.  相似文献   

12.
The consequences of a cosmological term varying asS –2 in a spatially isotropic universe with scale factorS and conserved matter tensor are investigated. One finds a perpetually expanding universe with positive and gravitational constantG that increases with time. The hard equation of state 3P>U (U mass-energy density,P scalar pressure) applied to the early universe leads to the expansion lawSt (t cosmic time) which solves the horizon problem with no need of inflation. Also the flatness problem is resolved without inflation. The model does not affect the well known predictions on the cosmic light elements abundance which come from standard big bang cosmology.In the present, matter dominated universe one findsdG/dt=2H/U (H is the Hubble parameter) which is consistent with observations provided <10–57 cm–2. Asymptotically (S) the term equalsGU/2, in agreement with other studies.  相似文献   

13.
Zusammenfassung Es wird gezeigt, daß die unter der Einwirkung einer Momentenimpulsserie entstehende Bewegung eines rotierenden Flugkörpers mit Nutationsdämpfung sich vollständig einem regelmäßigen Polygon entnehmen läßt, das durch das Trägheitsmomentenverhältnis, den Integralwert eines Einzelimpulses, den Drall und eine die Dämpfung charakterisierende KonstanteK 0 bestimmt ist.Die Bewegung setzt sich aus logarithmischen Spiralen zusammen, derenn-ten Anfangsradius man erhält, indem man den Teilungspunkt des im VerhältnisK 0:1 geteilten (n–1)-ten Radius mit der (n+1)-ten Polygonecke verbindet.Es wird bewiesen, daß das Konstruktionsnetz zu einem im äußeren Polygon liegenden ähnlichen inneren Polygon konvergiert, das gegenüber ersterem gedreht ist.Einfache Beziehungen zur Bewegungsbestimmung mit dem Polygonschema werden für Pulsfrequenzen angegeben, die ganzzahlige Vielfache oder Bruchteile der Spinfrequenz sind.
It is shown that the motion of a spinning body with nutation damping due to a series of torque pulses can be completely derived from a regular polygon determined by the ratio of inertias, the integral of one pulse, the momentum and a constantK 0 characterizing damping.The motion is composed of spirals thenth initial radius of which is obtained by connecting the dividing point of the (n–1)th radius with the (n+1)th polygon corner. Each dividing point divides the respective radius in the ratioK 0:1. The net of construction lines converges into an inner polygon turned against the outer one and having the same shape.Simple rules are shown for the application of the scheme on pulse frequencies which are multiples or fractions of spin frequency.
Symbole 1-2-3 Achsen des flugkörperfesten Koordinatensystems - a,b,c Hilfsgrößen zur Bestimmung der Iterationsgrößen - E i i-te Polygonecke - H Drall des Flugkörpers - K i Verhältnis deri-ten Drehzeigerlängen zu Beginn und am Ende eines Impulses - M Iterationsmatrix - Integralwert des Momentenimpulses - P 0 Äußeres Polygon - P 1 Spitze des Drehzeigersr 00e - P Drehpunkt des Drehzeigersr 00 - P Konvergierendes Polygon - P i Teilungspunkt des [i–1]-ten Zeigers - r 0i Drehzeiger aufgrund desi-ten Impulses allein - r 0ia Zeigerr 0i in Anfangslage - r 0ie Zeigerr 0i in Endlage - r i i-ter Summenzeiger - r ia Zeigerr i in Anfangslage - r ie Zeigerr i in Endlage - T Dauer einer Flugkörperumdrehung - t,t, Zeitargumente - x-y-z Achsen eines raumfesten Koordinatensystems - x i ,y i Iterationskoordinaten - n Phase desn-ten Radius gegenüber der anliegenden Polygonseite - Drehung des inneren Polygons gegenüber dem äußeren - Abklingkonstante - Phasenänderung des Drehzeigers innerhalb einer Flugkörperumdrehung - 0 Anteil der über 2 hinausgehenden Phasenänderung des Drehzeigers - 3 Trägheitsmoment um die Spinachse - 12 Trägheitsmoment um die Querachsen - Zahl der Ecken des Konstruktionspolygons - 1,2 Eigenwerte der Iterationsmatrix - Zahl der vollen Umläufe des Konstruktionspolygons - Fortbewegungsachse des Drallvektors - 0 Ausgangsphasenwinkel - i Phasenlage desi-ten Summenzeigers - x, y Drehwinkel nach Einzelimpuls fürt - , Funktionen der Iterationsgrößen - , Drehwinkel umx-bzw.y-Achse - Drehgeschwindigkeit der Spinachse um den Drallvektor - Fiktive Größen bei Pulsfrequenzen kleiner als Spinfrequenz - Fiktive Größen bei Pulsfrequenzen größer als Spinfrequenz  相似文献   

14.
In the last four years we have carried out a number of studies on the radiative and collisional processes in theA 2 i state of CN. Many of these of interest to those studying planetary atmospheres, comets and solar spectra are summarized in this paper. Data for CNA 2 i fluorescence lifetimes and quenching rates, and collisional energy transfer between CNA 2 i andX 2+ are reported. Detailed comparisons and a discussion of the results may be found in several already published papers.  相似文献   

15.
The position of bright knots of 30 flares at their very beginning relative to the high-resolution isogauss maps of the longitudinal component (H ) and maps of the transverse component (H ) of magnetic field are considered for seven days during the passage of the active and large spot group in Sept. 1963 (see Table I and maps on Figures 1–8).The flare bright knots occur simultaneously in regions of opposite magnetic polarity, and the majority of these knots are adjacent to neutral line H = 0, although not coinciding precisely with this line (Figure 9). Lenticular form of flare knots and the motions of bright material of flares is restrained by transversal field H . Also flares are closely associated (83%) with so-called bifurcated regions, where specific crossing of transverse components takes place (Figures 4–5). There is well-expressed (80%) coincidence of flare knots with the strongest (positive or negative) electric currents as determined from the relation j = c/4 rot H. The relation of results obtained to some existing theories of flares is briefly discussed.U.S. Nat. Acad. of Science - U.S.S.R. Acad. Nauk. Exchange Scientist Program; now at CSIRO Division of Physics, Australia.  相似文献   

16.
Results from wind ionization calculations are presented which show how the P-Cygni profiles of superionized species such as O VI can provide information about the X-ray source characteristics of early-type stars. Using detailed radiative and atomic physics models, we find that a significant source of X-ray emission from Pup (O4 If) comes from a region in the wind located within roughly 1 to 2 stellar radii of the photosphere. Our results suggest that X-rays sources in which emission occurs exclusively at large radii (r a fewR * ) are inconsistent with UV P-Cygni profiles for O VI. Instead, we find that X-ray emission from shocks distributed throughout the lower regions of the wind (r 1 – 2R * ) is consistent with both X-ray and UV data, as well as mass loss rates deduced from radio andH observations.  相似文献   

17.
The simplest, conventional, and original form of the circular restricted problem of three bodies is briefly described in sidereal and synodic systems using dimensional and non-dimensional variables. This dynamical system is generalized to n2 primary bodies (from n=2) with masses Mi, 1in, interacting with arbitrary force laws (instead of only gravitational forces). The number of bodies of small mass mMi not perturbing the primaries is increased from =1 to 1 where 1 and the minor bodies are allowed to interact with one another under arbitrary force laws. While the minor bodies (m) do not affect the motions of the primaries (Mi), the primaries influence the motions of the minor bodies with arbitrary force laws.For the case where n=2, 1, and only gravitational forces act on the system, an integral of the system is derived. It is shown that the energy integral of the general problem of N bodies and the Jacobian integral of the classical restricted problem of three bodies are limiting cases of this integral. The role of the integral in bounding the motion of the minor bodies is discussed. Several applications of this system are given.  相似文献   

18.
An account is given of the results of a comparison of existing basic selenodetic systems in the equatorial zone of the Moon together with plan and altitude data, which have been provided by means of a specially worked out method, based on the use of the LAC charts of the Moon (scale 1:1000000), and which does not require the presence of common catalogued reference points. It is shown that systematic differences of the form () for different catalogues are, on the whole, relatively small and do not exceed 2. Systematic differences of the form () have a minimum in the region = ± 20° and significantly increase towards the edges of the visible disk, where they may attain a value of 6 between catalogues. Random errors in latitude have on the whole, a similar behaviour in different catalogues, being practically independent of longitude and not exceeding 3. Random errors in longitude significantly increase towards the limb regions in all the studied catalogues, and may reach values of 6 to 8. Author's estimates of the accuracy of absolute heights in selenodetic catalogues is not always sufficiently precise; in certain cases it was found that the accuracy was underestimated by a factor of one and a half. The data on relative heights in the LAC charts are expressed with a vertical step of 300 m, errors in these values are of the order of 250 m for each step in height. As a result of the comparison a set of better points has been obtained forming a catalogue which may be referred to as LPL. The selection was made on the basis of magnitude and character of both the systematic and random errors.  相似文献   

19.
The Main-Sequence positions as well as the evolutionary behavior of Population III stars up to an evolution age of 2×1010 yr, taking this time as the age of the Universe, have been investigated in the mass range 0.2 and 0.8M . While Population III stars with masses greater than 0.3M develop a radiative core during the approach to the Main Sequence, stars with masses smaller than 0.3M reach the Main Sequence as a wholly convective stars. Population III stars with masses greater than 0.5M show a brightening of at most 2.2 in bolometric magnitude when the evolution is terminated as compared to the value which corresponds to zero-age Main Sequence. The positions of stars with masses smaller than 0.5M remain almost the same in the H-R diagram.If Population III stars have formed over a range of redshifts, 6相似文献   

20.
In this paper we adopt the method of relativistic fluid dynamics to examine the number density distribution of stars around a massive black hole in the core of stellar clusters. We obtain extensive results,n(r) r –a, 3/2a9/2, which include, respectively, then(r) r –7/4 power law obtained by Bahcall and Wolf and then(r) r –9/4 power law by Peebles. Sincen(r) is not an observable quantity for star clusters, we also consider general relativity effects, i.e., the consequence of the bending of light, in calculating the projected density of stars in such a system. As an example we employ a massive black hole 103 M inlaid in the center of a globular cluster and calculate various projected densities of stars. The results show that cusp construction occurs in all cases unless the central black hole massM=0, and the polytropic index does not affect at all the position of the capture radiusr a. The obvious differences in the surface density is only embodied in the interior of the capture radius. At the outer regions of the core, the surface density of stars declines rapidly with ar –5 power law in all cases. These results can be applied to cases of unequal-mass and non-steady state.  相似文献   

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