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1.
The sub-iron-iron flux ratio in cosmic rays at an atmospheric depth of 9.8 g cm–2 has been estimated using a balloon-borne CR-39 (HCB) stack launched from Alice Springs for 32 hours. The recovered and chemically etched plates were analysed optically and the measured etch pit diameters yielded the sub-iron-iron flux ratio at the flight altitude. The sub-iron-iron flux ratio has been corrected for the top of the atmosphere by considering the loss of heavy ions due to nuclear interaction and fragmentation. The present result has been compared with the result expected from the source composition derived by Protheroeet al. as well as other authors. 相似文献
2.
Bianchi type V viscous fluid cosmological model for barotropic fluid distribution with varying cosmological term Λ is investigated. We have examined a cosmological scenario proposing a variation law for Hubble parameter H in the background of homogeneous, anisotropic Bianchi type V space-time. The model isotropizes asymptotically and the presence of shear viscosity accelerates the isotropization. The model describes a unified expansion history of the universe indicating initial decelerating expansion and late time accelerating phase. Cosmological consequences of the model are also discussed. 相似文献
3.
In recent years, Hartley Transform (HT) as a substitute of much widely used Fourier Transform (FT) has been practised in science and industries. The advantage of faster computation of HT is enormous when one is dealing with very long data sets. One such application arises in computation of parameters of Free Oscillations of the Earth (FOE), where one needs to study very long period vibrations of the earth, excited after a large earthquake. We demonstrate here an application of HT to determine the parameters of these normal modes of the earth after the Minahasa Peninsula earthquake of 18 April 1990 (Ms = 7.5). 相似文献
4.
Pratibha Thakuria Das Liagi Tajo Jonali Goswami 《Journal of the Indian Society of Remote Sensing》2009,37(2):317-324
Orange orchards of Meghalaya are small in size and are found together with other plants on the slopes of hills. It is also
reported that the productivity of orchards is declining in some parts of the state. Therefore in this study, we have attempted
to map areas prone to citrus productivity decline based on the integrated effect of soil erosion, vegetation condition and
moisture stress. It is difficult to identify orchards on hilly terrain using standard FCC of IRS-P6 LISS III data. Hence,
an enhanced color composite image was prepared from three images generated from indices namely SBI, NDWI and NDVI. This enhanced
color image was classified using the maximum likelihood classification method and enabled identifying villages prone to citrus
decline. The study shows that orchards of 29 villages which are suffering from moisture stress and mostly located on steep
slopes that cause heavy soil loss leading to nutrient imbalances are prone to citrus decline. These data will be useful in
mapping potential citrus decline areas over zones having similar climatic conditions so that the concerned state horticulture/agriculture
departments and citrus growers can take necessary remedial actions. 相似文献
5.
We obtain a new parametric class of exact solutions of Einstein–Maxwell field equations which are well behaved. We present a charged super-dense star model after prescribing particular forms of the metric potential and electric intensity. The metric describing the super dense stars joins smoothly with the Reissner–Nordstrom metric at the pressure free boundary. The electric density assumed is where n may take the values 0,1,2,3,4 and so on and K is a positive constant. For n=0,1 we rediscover the solutions by Gupta and Maurya (Astrophys. Space Sci. 334(1):155, 2011) and Fuloria et al. (J. Math. 2:1156, 2011) respectively. The solution for n=2 have been discussed extensively keeping in view of well behaved nature of the charged solution of Einstein–Maxwell field equations. The solution for n=3 and n=4 can be also studied likewise. In absence of the charge we are left behind with the regular and well behaved fifth model of Durgapal (J. Phys. A 15:2637, 1982). The outmarch of pressure, density, pressure-density ratio and the velocity of sound is monotonically decreasing, however, the electric intensity is monotonically increasing in nature. For this class of solutions the mass of a star is maximized with all degree of suitability, compatible with Neutron stars and Pulsars. 相似文献
6.
We present a new spherically symmetric solution of the general relativistic field equations in isotropic coordinates. The
solution is having positive finite central pressure and positive finite central density. The ratio of pressure and density
is less than one and casualty condition is obeyed at the centre. Further, the outmarch of pressure, density and pressure-density
ratio, and the ratio of sound speed to light is monotonically decreasing. The solution is well behaved for all the values
of u lying in the range 0<u≤.186. The central red shift and surface red shift are positive and monotonically decreasing. Further, we have constructed
a neutron star model with all degree of suitability and by assuming the surface density ρ
b
=2×1014 g/cm3. The maximum mass of the Neutron star comes out to be M=1.591 M
Θ with radius R
b
≈12.685 km. The most striking feature of the solution is that the solution not only well behaved but also having one of the
simplest expressions so far known well behaved solutions. Moreover, the good matching of our results for Vela pulsars show
the robustness of our model. 相似文献
7.
The analysis of tracking loops for global navigation satellite systems (GNSS) receivers is often confined to Monte Carlo approaches that can result in long simulation times and a limited number of simulation runs. A different approach based on Semi-Analytic principles is considered here. Matlab® code implementing a Semi-Analytic framework for the fast simulation of GNSS digital tracking loops is presented. The code structure is detailed and two specific examples implementing a standard PLL and the Double Estimator for unambiguous binary offset carrier (BOC) tracking are provided. The code has been organized in a modular way, and can be easily modified for the simulation of different tracking loops. 相似文献
8.
A non-singular exact solution with an infinite central density is obtained for the interior of spherically symmetric and static
structures. Both the energy density and the pressure are infinite at the center but we have e
λ(0)=1 and e
ν(0)≠0. The solution admits the possibility of receiving signals from the region of infinite pressure. 相似文献
9.
The antiproton-proton flux ratio has been estimated from the closed galaxy model of Peters and Westergaard by using the latest primary nucleon spectrum and
inclusive reaction accelerator results. The derived
flux ratio is about three times higher than those expected from the leaky box model. The results have been compared with the previous estimates by different authors. 相似文献
10.
A new class of relativistic perfect fluid cylinders with expansion proportional to shear scalar have been derived by considering
the Einstein-Rosen metric. It is shown that the solutions obtained by other workers do not satisfy the isotropy conditions
and therefore are erroneous. The solutions derived in this article are analyzed kinematically. 相似文献