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941.
Bianchi type-Ⅲ bulk viscous barotropic fluid cosmological model with variables G and A is investigated. To obtain the realistic model, we assume the conditions between the metric potentials A, B, C as A/A = B/B = m1/t^N and C/C = m2/t^n, P = p - 3ηH, η =ηop^s, p=γρ, 0 ≤ γ ≤ 1, where p is isotropic pressure,η the coefficient of bulk viscosity, η0 and S the constants, H the Hubble constant, m1 = 2m2 where m1 〉 0, m2 〉 O. The solutions obtained lead to inflationary phase and the results obtained match with the observations. The case n = 1 for S = 1 is also discussed, relating the results with the observations. 相似文献
942.
We have investigated Bianchi Type V barotropic perfect fluid cosmological model in Lyra geometry. To get the deterministic
model of the universe, we have assumed the barotropic perfect fluid condition p=γ
ρ, 0≤γ≤1 and energy conservation equation i.e. T
i;j
j
=0. The physical and geometrical aspects of the model are discussed. The special cases for γ=1 (stiff fluid distribution), γ=0 (dust distribution), γ=1/3 (disordered radiation) are also discussed. 相似文献
943.
P. Praveen Kumar S. Tamilselvan Victor Antony Raj J. Madhavan 《Optics Communications》2008,281(10):2989-2995
Single crystals of pure, Cu2+and Mg2+ doped l-histidine acetate (LHA) were grown successfully by slow evaporation technique. The X-ray diffraction (XRD) studies were carried out for the pure and doped grown crystals. Absorption of these grown crystals was analyzed using UV-vis-NIR studies, and it was found that these crystals possess minimum absorption from 200 nm to 1500 nm. The pure and doped crystals are characterized by Fourier transform Raman (FT-Raman), thermal and photoconductivity studies. Vickers microhardness tests were carried out for the pure and doped crystals and the mechanical strengths were found. The dielectric constant and the dielectric loss with frequency were also studied. 相似文献
944.
We study the heat current J in a classical one-dimensional disordered chain with on-site pinning and with ends connected to stochastic thermal reservoirs at different temperatures. In the absence of anharmonicity all modes are localized and there is a gap in the spectrum. Consequently J decays exponentially with system size N. Using simulations we find that even a small amount of anharmonicity leads to a J approximately 1/N dependence, implying diffusive transport of energy. 相似文献
945.
Several networks occurring in real life have modular structures that are arranged in a hierarchical fashion. In this paper,
we have proposed a model for such networks, using a stochastic generation method. Using this model we show that, the scaling
relation between the clustering and degree of the nodes is not a necessary property of hierarchical modular networks, as had
previously been suggested on the basis of a deterministically constructed model. We also look at dynamics on such networks,
in particular, the stability of equilibria of network dynamics and of synchronized activity in the network. For both of these,
we find that, increasing modularity or the number of hierarchical levels tends to increase the probability of instability.
As both hierarchy and modularity are seen in natural systems, which necessarily have to be robust against environmental fluctuations,
we conclude that additional constraints are necessary for the emergence of hierarchical structure, similar to the occurrence
of modularity through multi-constraint optimization as shown by us previously.
相似文献
946.
Sally Prime Julie Dearnley Andrew M. Ventom Raj B. Parekh Christopher J. Edge 《Journal of chromatography. A》1996,720(1-2):263-274
Exo- and endoglycosidases are used to sequence oligosaccharides and give valuable information on the monosaccharide sequence, together with the anomericity, the stereochemistry, and in some cases, the substitution pattern of the monosaccharides. Both sequential and parallel methods of oligosaccharide sequencing are discussed. 相似文献
947.
We have measured the heat capacity of superconducting, single phase YBa2Cu3O7 in the temperature range 2 to 18 K. An extrapolation of the data between 4 and 9 K gives aC/T (T → 0) of ∼ 25 mJ/mole K2. The Debye temperature obtained from the high temperature linear portion ofC/T vsT
2 plot is 325 K. 相似文献
948.
Raj N. Misra 《Tetrahedron letters》1985,26(16):1973-1976
The synthesis of methylene cyclopropane arachidonic acid analogs and is described. 相似文献
949.
950.
Summary The pseudo Green's function theory for dilute alloys ofd-band metals is used to study the electronic structure ofCuNi,CuCo andAgNi alloys. The calculated densities of state are found in agreement with other available results. The virtual bound states
with double-hump structure are found at 0.514, 0.54 and 0.4 Ryd forCuNi,CuCo andAgNi alloys, respectively.
Riassunto La teoria della pseudo funzione di Green per leghe diluite di metalli nella bandad è usata per studiare la struttura elettronica delle legheCuNi,CuCo eAgNi. Si trova che le densità di stato calcolate sono in accordo con altri risultati disponibili. Gli stati legati virtuali con struttura a doppia sporgenza si trovano a 0.514, 0.54 e 0.4 Ryd per leghe diCuNi,CuCo eAgNi.
Резуме Используется теория псевдо-гриновских функций для разбавленных сплавов металловd-зоны, чтобы исследовать злектронную структуруCuNi,CuCo иAgNi. Получено, что вычисленная плотность состояния согласуется с другими имеющимися результатами. Обнаружены виртуальные связанные состояния, имеюшие структуру с двойным максимумом, при 0.514, 0.54, 0.4 Ry соответственно для сплавовCuNi,CuCo иAgNi.相似文献