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41.
S. C. Tripathy Brajesh Kumar Kiran Jain A. Bhatnagar 《Journal of Astrophysics and Astronomy》2000,21(3-4):357-360
Using intermediate degreep-mode frequency data sets for solar cycle 22, we find that the frequency shifts and magnetic activity indicators show a “hysteresis”
phenomenon. It is observed that the magnetic indices follow different paths for the ascending and descending phases of the
solar cycle while for radiative indices, the separation between the paths are well within the error limits. 相似文献
42.
The community structure of zooplankton was studied in relation to physico-chemical characteristics of the river Chambal polluted by industrial effluents and domestic sewage near Nagda. Thirtytwo species of zooplankton of five main groups, viz. Protozoa, Rotifera, Cladocera, Copepoda and Ostracoda were observed at pre-pollution sampling stations. The abundance, distribution, total population, group percentage and species diversity were studied and correlated with pollution-indicating parameters. Species diversity values indicated a decrease from the sampling station near a pre-effluent point to an effluent discharge channel and an increase at a post-effluent discharge point revealing a slight recovery zone. Keratella tropica and Kellicottia sp. were identified as pollution tolerant taxa. 相似文献
43.
Bharat Lohani Nishant Bhatnagar Aditya Roshan 《Journal of the Indian Society of Remote Sensing》2008,36(1):1-11
ISRO is launching a LiDAR instrument (LLRI) onboard Chandrayan-I. The LLRI will collect topographic data of lunar surface.
Flying at an altitude of 100km the LLRI will have a footprint of 100m on the moon surface. Time of travel measurement, which
is fundamental for topographic coordinate computation, depends upon the shape of the return pulse. This shape in turn is a
function of the characteristics of footprint, i. e. its geometry, reflectance and roughness. This paper uses a mathematical
model to simulate the return waveform at the receiver for different conditions of said characteristics within the footprint.
Mathematical equations are employed to generate footprints that vary in their characteristics in terms of reflectance, geometry
and roughness. A footprint is divided into small bins so that each bin has uniform property. Energy distribution in transmitted
pulse is considered Gaussian. Energy irradiated over footprint is approximated using the assumed distribution. For each bin
the energy incident is computed and accordingly the quantum and distribution of reflected energy is determined. The final
waveform is generated by integrating the energy returned from all the bins according to their time of arrival and spread.
Some results are presented to show the performance of the developed system. 相似文献
44.
45.
We have studied periodic orbits generated by Lagrangian solutions of the restricted three body problem when one of the primaries
is an oblate body. We have determined the periodic orbits for different values of μ, h and A (h is energy constant, μ is mass ratio of the two primaries and A is an oblateness factor). These orbits have been determined by giving displacements along the tangent and normal to the mobile
coordinates as defined by Karimov and Sokolsky (Celest. Mech. 46:335, 1989). These orbits have been drawn by using the predictor-corrector method. We have also studied the effect of oblateness by
taking some fixed values of μ, A and h. As starters for our method, we use some known periodic orbits in the classical restricted three body problem. 相似文献
46.
Observations and analyses of two similar eruptive prominences on the north-east limb observed on 1980 April 27 at 0231 and
0517 UT, which are associated with the Boulder active region No. 2416 are presented. Both the eruptive prominences gave rise
to white-light coronal transients as observed by C/P experiment of High Altitude Observatory on the Solar Maximum Mission.
Type II and moving type IV radio bursts are reported in association with the first Hα eruptive prominence at 0231 UT.
Both the Hα eruptive prominences showed pulse activity with a quasi-periodicity of about 2–4 min. We estimate a magnetic field
in the eruptive prominence of about 100 G and a build-up rate ∼ 1026 ergs-1. The high build-up rate indicates that the shearing of the photospheric magnetic field, which fed the energy into the filament,
was rapid. It is proposed that fast-moving Hα features must have initiated the observed coronal transients. From Hα, type
II and coronal-transient observations, we estimate a magnetic field of 2.8 G at 1.9R⊙ from the disc centre, which agrees well with the earlier results. 相似文献
47.
The analysis of two-parameter families of triple close approaches occurring in stellar systems is studied in a series of three
papers. This paper deals with the role of triple encounters with low initial velocities and equal masses in the evolution
of stellar systems. It shows how a condition of complete collapse may be perturbed to obtain well-established two-parameter
families of asymmetric triple close approaches with the formation of a binary and with systematic regularity of escape of
the third body. Our results also indicate that the conjecture of Szebehely viz., `The measure of escaping orbits is significantly
higher than the measure of stable orbits' is likely to be true. Further our results differ from that of Agekian's escape probability
criterian. The second paper deals with the role of triple encounters with low initial velocities and equal masses in the evolution
of stellar systems in 3D space. The third and last paper offers applications in stellar systems.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
48.
The location and the stability in the linear sense of the libration points in the restricted problem have been studied when there are perturbations in the potentials between the bodies. It is seen that if the perturbing functions satisfy certain conditions, there are five libration points, two triangular and three collinear. It is further observed that the collinear points are unstable and for the triangular points, the range of stability increases or decreases depending upon whetherP> or <0 wherep depends upon the perturbing functions. The theory is verified in the following four cases:
- There are no perturbations in the potentials (classical problem).
- Only the bigger primary is an oblate spheroid whose axis of symmetry is perpendicular to the plane of relative motion (circular) of the primaries.
- Both the primaries are oblate spheroids whose axes of symmetry are perpendicular to the plane of relative motion (circular) of the primaries.
- The primaries are spherical in shape and the bigger is a source of radiation.
49.
S. P. Bhatnagar Vijaykumar S. D. Verma 《Journal of the Indian Society of Remote Sensing》1988,16(1):7-9
A microprocessor based system for acquiring, processing and displaying analog data from two channels is described. The system will be particularly useful in two parameter pulse height analysis type applications. Software aided display can produce three dimensional display (on X-Y plotter or screen of oscilloscope) which can be rotated to view from four sides, such that various small features which are close to a major peak could be resolved by rotational viewing technique. 相似文献
50.
The in-plane motion of a Geosynchronous satellite under the gravitational effects of the sun, the moon and the oblate earth
has been studied. The radial deviation (Δr) and the tangential deviation (r
cΔθ) have been determined. Herer
c represents the synchronous altitude. It has been seen that the sum of the oscillatory terms in Δr for different inclinations is a small finite quantity whereas the sum of the oscillatory terms inr
cΔθ for different inclinations is quite large due to the presence of the low-frequency terms in the denominator 相似文献