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11.
Spatially-homogeneous and anisotropic-vacuum Bianchi type-VI0 cosmological models are obtained in scalar-tensor theories of gravitation proposed by Ross and Dunn. Some physical properties of the models are also discussed. 相似文献
12.
Chandrashekhar M. Biradar Prasad S. Thenkabail Praveen Noojipady Yuanjie Li Venkateswarlu Dheeravath Hugh Turral Manohar Velpuri Murali K. Gumma Obi Reddy P. Gangalakunta Xueliang L. Cai Xiangming Xiao Mitchell A. Schull Ranjith D. Alankara Sarath Gunasinghe Sadir Mohideen 《International Journal of Applied Earth Observation and Geoinformation》2009
The overarching goal of this study was to produce a global map of rainfed cropland areas (GMRCA) and calculate country-by-country rainfed area statistics using remote sensing data. A suite of spatial datasets, methods and protocols for mapping GMRCA were described. These consist of: (a) data fusion and composition of multi-resolution time-series mega-file data-cube (MFDC), (b) image segmentation based on precipitation, temperature, and elevation zones, (c) spectral correlation similarity (SCS), (d) protocols for class identification and labeling through uses of SCS R2-values, bi-spectral plots, space-time spiral curves (ST-SCs), rich source of field-plot data, and zoom-in-views of Google Earth (GE), and (e) techniques for resolving mixed classes by decision tree algorithms, and spatial modeling. The outcome was a 9-class GMRCA from which country-by-country rainfed area statistics were computed for the end of the last millennium. The global rainfed cropland area estimate from the GMRCA 9-class map was 1.13 billion hectares (Bha). The total global cropland areas (rainfed plus irrigated) was 1.53 Bha which was close to national statistics compiled by FAOSTAT (1.51 Bha). The accuracies and errors of GMRCA were assessed using field-plot and Google Earth data points. The accuracy varied between 92 and 98% with kappa value of about 0.76, errors of omission of 2–8%, and the errors of commission of 19–36%. 相似文献
13.
D. R. K. Reddy CH. C. S. V. V. R. Murthy R. Venkateswarlu 《Astrophysics and Space Science》2006,301(1-4):79-82
Field equations in the presence of a perfect fluid distribution are obtained in a scalar-tensor theory of gravitation proposed
by Saez and Ballester (Phys. Lett. 113, 1985, 467) with the aid of Einstein–Rosen cylindrically symmetric metric. A static vacuum model and a non-static stiff fluid
model are presented. The physical and geometrical properties of the stiff fluid model are studied. 相似文献
14.
Exact Bianchi types-II, VIII and IX cosmological models are obtained in the scale covariant theory of gravitation. Some physical and geometrical properties of the models are studied. 相似文献
15.
K. Shanthi V. U. M. Rao D. R. K. Reddy R. Venkateswarlu 《Astrophysics and Space Science》1991,175(2):241-245
Spatially-homogeneous and anisotropic-vacuum Bianchi type-III cosmological models are obtained in scalar-tensor theories of gravitation proposed by Ross and Dunn. Some physical properties of the models are also discussed. 相似文献
16.
A static conformally flat spherically-symmetric perfect fluid cosmological model based on Lyra's modified Riemannian geometry is proposed. Some properties of the model are discussed. 相似文献
17.
Spatially-homogeneous and anisotropic Bianchi type-I cosmological models are obtained, in Barber's second self-creation theory of gravitation, when the source of the gravitational field is a perfect fluid. Some physical and geometrical properties of the models are discussed. 相似文献
18.
The exterior field of the Biachi type-II metric in the Lyttleton-Bondi universe is considered and an exact cosmological model is presented. The behaviour of the model is also discussed. 相似文献
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20.
The exterior field of the Bianchi type-V metric in the Lyttleton-Bondi universe is considered. It is shown that the Bianchi type-V Lyttleton-Bondi universe, under certain conditions, does not exist. 相似文献