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611.
R. C. Srivastava D. Leutloff J. P. Vishwakarma Arun Kumar 《Astrophysics and Space Science》1986,122(1):33-40
Magnetogasdynamic shock waves propagating in a medium of increasing density are discussed. The shock travels in a dense atmosphere. We have used the Runge-Kutta method to obtain a numerical solution of the problem. The distribution of flow variables behind the shock are shown by graphs. 相似文献
612.
R. K. Srivastava 《Astrophysics and Space Science》1987,129(1):143-147
A new period (P=3d.687664) of the eclipsing binary system IZ Persei is given, based on 16 observed times of the minima. O–C diagrams of IZ Per have been presented for the first time, and the period variations have been estimated in different portions of the O–C diagram. Significant period changes do not appear to have occurred in IZ Per. The O–C diagrams suggest that the period of the system is continuously increasing at a rate of 25s yr–1. Period variations of the order of 10–5 d appear to have occurred around the years 1969, 1972, and 1978. The period increases are stronger than the period decreases; but these are yet to be confirmed. The overall picture of IZ Per suggests that strong period changes are not present in the system; however, slow increase of period is apparent in IZ Per. The total period change (3×10–6 d) till the last epoch is in agreement with the newly derived period of IZ Per. 相似文献
613.
The excitation mechanism for O2 Herzberg Bands as given by Young and Black (1966) is examined. It is found that O2 Herzberg Bands are heavily quenched by N atoms, while (0,0) and (0,1) Atmospheric Bands are quenched mainly by CO, NO, O2 and N2, NO, O2 respectively. The emission of Herzberg Bands is found to arise from two layers centred at 80 and 100 km. The rate coefficients of a number of quenching reactions involving atmospheric gases are obtained theoretically. 相似文献
614.
The photoelectric elements of the system EI Cephei have been determined inU, B, V colours. The absolute dimensions have been determined and some evolutionary aspects have been discussed. A modified period of 8d.439334 has been obtained. The system is a detached one. 相似文献
615.
The shock wave produced by a point source has been studied in a heat-conducting gas medium. The shock is assumed to be strong enough to neglect the ambient gas pressure and the similarity method is used. The distribution of flow quantities behind the shock have been obtained by the numerical integration of a system of ordinary differential equations using the boundary conditions at the shock wave. 相似文献
616.
This paper aims at presenting a unified study of the Voigt functionsK(x,y) andL(x,y) which play a rather important role in several diverse fields of physics such as astrophysical spectroscopy and the theory of neutron reactions. Explicit expressions for these functions are given in terms of relatively more familiar special functions of one and two variables; indeed, each of these representations will naturally lead to various other needed properties of the Voigt functions. 相似文献
617.
Sarnam Singh T. P. Singh Gaurav Srivastava 《Journal of the Indian Society of Remote Sensing》2005,33(4):547-563
Improving image classification and its techniques have been of interest while handling satellite data especially in hilly
regions with evergreen forests particularly with indistinct ecotones. In the present study an attempt has been made to classify
evergreen forests/vegetation in Moulirig National Park of Arunachal Pradesh in Eastern Himalayas using conventional unsupervised
classification algorithms in conjunction with DEM. The study area represents climax vegetation and can be broadly classified
into tropical, subtropical, temperate and sub-alpine forests. Vegetation pattern in the study area is influenced strongly
by altitude, slope, aspect and other climatic factors. The forests are mature, undisturbed and intermixed with close canopy.
Rugged terrain and elevation also affect the reflectance. Because of these discrimination among the various forest/vegetation
types is restrained on satellite data. Therefore, satellite data in optical region have limitations in pattern recognition
due to similarity in spectral response caused by several factors. Since vegetation is controlled by elevation among other
factors, digital elevation model (DEM) was integrated with the LISS III multiband data. The overall accuracy improved from
40.81 to 83.67%. Maximum-forested area (252.80 km2) in national park is covered by sub-tropical evergreen forest followed
by temperate broad-leaved forest (147.09 km2). This is probably first attempt where detailed survey of remote and inhospitable areas of Semang sub-watershed, in and around
western part of Mouling Peak and adjacent areas above Bomdo-Egum and Ramsingh from eastern and southern side have been accessed
for detailed ground truth collection for vegetation mapping (on 1:50,000 scale) and characterization. The occurrence of temperate
conifer forests and Rhododendron Scrub in this region is reported here for the first time. The approach of DEM integrated
with satellite data can be useful for vegetation and land cover mapping in rugged terrains like in Himalayas. 相似文献
618.
R. P. Singh V. N. Sridhar V. K. Dadhwal R. Jaishankar M. Neelkanthan A. K. Srivastava G. D. Bairagi N. K. Sharma S. A. Raza Rajesh Sharma Manoj Yadav F. K. Joshi N. L. Purohit 《Journal of the Indian Society of Remote Sensing》2005,33(1):93-98
This paper presents results of a pilot study in six villages located in the states of Haryana, Rajasthan and Madhya Pradesh, to evaluate accuracy of crop area at village level estimated by IRS - LISS-I1I data with respect to detailed field survey carried out by National Sample Survey Organization. The selected villages were located in Karnal, Kota and Bhopal districts which represented single dominant wheat crop as well as wheat-mustard and wheat-gram situation, respectively. Accuracy assessment of remote sensing based estimate with field survey of NSSO showed relative deviation in wheat estimate ranging from 3.72 percent for Mainmati village in Karnal district in Haryana to 22.65 percent fo Ranpur village in Kota district of Rajasthan. It was found that relative deviation in area estimation is inversely poportional to the crop proportion in that village. Observations of over estimation at low crop proportion and underestimation at higher crop proportion was explained by simple budgeting of relative proportion of ommision and commision errors. The study demonstrates that on the average, 90 percent crop area accuracy is possible with LISS-II1 data and the adopted approach. 相似文献
619.
Two magnetometer array experiments were conducted in India during 1978–1980, under an Indo-Australian collaboration project, using 21 Australian three-component magnetometers of the Gough-Reitzel type. The first array study was made in the northwestern region covering the Aravallis, the Punjab, and the lesser Himalaya, while the second experiment was carried out in the southern peninsular shield area. Both these sets of geomagnetic deep sounding (GDS) observations yielded valuable results on the crustal and upper mantle structure in the two geologically and geophysically important regions of India.Geomagnetic induction patterns observed in northwest India have revealed a variety of electrical conductivity structures. The primary conductivity structure providing paths for induced currents is found to be striking at right-angles to the Himalayan Mountains. The conductivity structure is indicated to be a northward continuation of the Aravalli belt and, thus, suggesting the continuation of the Indian shield at depth into the base of the Himalayan foothills under the Ganga basin.The induction effects observed in the southern tip of peninsular India are by far the most complex geophysical phenomenon due to the simultaneous occurrence of the sea coast, the crustal and upper mantle conductivity anomalies between India and Sri Lanka under the sea, and the day-time equatorial electrojet as part of the external heterogeneous inducing field. It is further complicated by the existence of a conductive step, structure along the coastline at the Moho boundary and a “graben” structure in the Palk Strait, as revealed by the array observations. 相似文献
620.
Exposure against two ppm chromium from K2Cr2O7 for 1 to 7 months produced increasing accumulation of chromium in the liver, kidneys, brain and bone of the freshwater fish Mystus vittatus. In gonads, the accumulation of chromium was progressive for the first 5 months (i.e., April to August), but not in the subsequent 2 months. After 4 months exposure, fish transferred to chromium–free freshwater had a significant depletion of chromium from all tissues at 1, 2 and 3 months. 相似文献