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41.
Tolman's V solution has found wide application to the redshift problems in astrophysics but it has a drawback that there is singularity at the centre. We have developed a two-density model with a parabolic density distribution in the core ande
r
2n
in the envelope. The most distinctive feature of the model is that there is a continuity of all four variables (E, P, , and ) at the boundary. In other analytic core-envelope models the continuity of only three varaibles is possible. This two-density structure has been used to model neutron stars and their mass, size, and red shifts have been obtained. 相似文献
42.
Thd H
3
+
molecular ion plays an important role in the chemistry of astronomical objects as it protonates the neutral species. The authors have recently calculated the partition functions of H
3
+
which may be used to compute the equilibrium constants for the chemical reaction H2+H2
+H
3
+
+H. In this short communication we have calculated the equilibrium constants for the temperature range from 500 to 8000 K. The results are also presented in the polynomial form. 相似文献
43.
In this work an exhaustive study of static massive configurations with a constant local adiabatic exponent (1) has been made under various physical conditions at the centre. The static parameters of these structures have been calculated at the extreme causality condition. These structures have been used to model neutron stars and the various neutron star parameters have been calculated. The radial pulsation and rotation of these configurations have also been discussed. 相似文献
44.
Orimoloye Israel R. Olusola Adeyemi O. Belle Johanes A. Pande Chaitanya B. Ololade Olusola O. 《Natural Hazards》2022,112(2):1085-1106
Natural Hazards - Droughts are particularly disastrous in South Africa and other arid regions that are water-scarce by nature due to low rainfall and water sources. According to some studies,... 相似文献
45.
46.
ABSTRACT The Dhidhessa River Basin (DRB), in the Abbay River Basin in Ethiopia, is undergoing large-scale dam construction for sugarcane irrigation. We focused on the dynamics of population migration, settlement, relocation and water resource development in the DRB using primary and secondary data. Two major migration waves were observed in the basin: the first in 1984–1986 during a severe drought and the second during 2005–2017. Most rural migrants were “pulled” by government initiative in the period 1984–2017, while a few migrated of their own accord due to famine. We found that the first migration wave from eastern Ethiopia (Harar) to DRB was due to scarcity of water, land and rainfall and the migration positively affected migrant livelihoods. In the second phase, dam construction displaced settled farmers and migrants, adversely affecting their livelihoods. Analysis is needed that considers the wellbeing of the displaced agrarian society and the migrant population in the dam-affected area. 相似文献
47.
Kanchan?PandeEmail author S.?K.?Pattanayak K.?V.?Subbarao P.?Navaneethakrishnan T.?R.?Venkatesan 《Journal of Earth System Science》2004,113(4):755-758
We report here a40Ar-39Ar age of 66.0 ± 0.9 Ma (2σ) for a reversely magnetised tholeiitic lava flow from the Bhimashankar Formation (Fm.), Giravali Ghat, western Deccan province,
India. This age is consistent with the view that the 1.8–2 km thick bottom part of the exposed basalt flow sequence in the
Western Ghats was extruded very close to 67.4 Ma. 相似文献
48.
A comparative study of ANN and Neuro-fuzzy for the prediction of dynamic constant of rockmass 总被引:1,自引:0,他引:1
Physico-mechanical properties of rocks have great significance in all operational parts in mining activities, from exploration
to final dispatch of material. Compressional wave velocity (p-wave velocity) and anisotropic behaviour of rocks are two such properties which help to understand the rock response under
varying stress conditions. They also influence the breakage mechanism of rock. There are different methods to determine thep-wave velocity and anisotropyin situ and in the laboratory. These methods are cumbersome and time consuming. Fuzzy set theory, Fuzzy logic and Neural Networks
techniques seem very well suited for typical geotechnical problems. In conjunction with statistics and conventional mathematical
methods, hybrid methods can be developed that may prove to be a step forward in modeling geotechnical problems. Here, we have
developed and compared two different models, Neuro-fuzzy systems (combination of fuzzy and artificial neural network systems)
and Artificial neural network systems, for the prediction of compressional wave velocity. 相似文献
49.
Rajneesh Bhutani Kanchan Pande T. R. Venkatesan 《Journal of Earth System Science》2004,113(4):737-754
New40Ar-39Ar thermochronological results from the Ladakh region in the India-Asia collision zone provide a tectono-thermal evolutionary
scenario. The characteristic granodiorite of the Ladakh batholith near Leh yielded a plateau age of 46.3 ± 0.6 Ma (2σ). Biotite from the same rock yielded a plateau age of 44.6 ± 0.3 Ma (2σ). The youngest phase of the Ladakh batholith, the leucogranite near Himya, yielded a cooling pattern with a plateau-like age
of ∼ 36 Ma. The plateau age of muscovite from the same rock is 29.8 ±0.2 Ma (2σ). These ages indicate post-collision tectono-thermal activity, which may have been responsible for partial melting within the
Ladakh batholith. Two basalt samples from Sumdo Nala have also recorded the post-collision tectono-thermal event, which lasted
at least for 8 MY in the suture zone since the collision, whereas in the western part of the Indus Suture, pillow lava of
Chiktan showed no effect of this event and yielded an age of emplacement of 128.2 ±2.6 Ma (2σ). The available data indicate that post-collision deformation led to the crustal thickening causing an increase in temperature,
which may have caused partial melting at the base of the thickened crust. The high thermal regime propagated away from the
suture with time. 相似文献
50.
The equivalent widths of P(51) and R(43) lines of the 1-0 and P(45) and R(56) lines of the 2-1 vibration rotation bands of SiO near 8 m region, have been computed for Zwaan's (1974) sunspot model at the centre of the disc. The predicted equivalent widths suggest a possible presence of these SiO bands in the sunspot spectrum. 相似文献