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排序方式: 共有1413条查询结果,搜索用时 31 毫秒
871.
Chayan Ranjit Shuvendu Chakraborty Ujjal Debnath 《International Journal of Theoretical Physics》2012,51(7):2180-2207
We have considered N-dimensional Einstein field equations in which four-dimensional space-time is described by a FRW metric and that of extra dimensions by an Euclidean metric. We have chosen the exponential forms of scale factors a and d numbers of b in such a way that there is no singularity for evolution of the higher dimensional Universe. We have supposed that the Universe is filled with K-essence, Tachyonic, Normal Scalar Field and DBI-essence. Here we have found the nature of potential of different scalar field and graphically analyzed the potentials and the fields for three scenario namely Emergent Scenario, Logamediate Scenario and Intermediate Scenario. Also graphically we have depicted the geometrical parameters named statefinder parameters and slow-roll parameters in the higher dimensional cosmology with the above mentioned scenarios. 相似文献
872.
The heterojunction structures of In2O3/TiO2, exhibiting visible light photocatalytic efficiency, has been synthesized by utilizing maleic acid as an organic linker to combine In2O3 and Degussa P25 (TiO2) nanoparticles. The prepared nanocomposite has been characterized by FESEM, TEM, XRD and UV?CVisible reflectance spectra. The photocatalytic efficiency of the composite photocatalyst has been investigated based on the decomposition of 2-propanol (IP) in gas phase and 1,4-dichlorobenzene (DCB) in aqueous phase under visible light (??????420?nm) irradiation. The results reveal that the In2O3/TiO2 composite photocatalyst with 7?wt% In2O3 demonstrated 6.3 times of efficiency in evolving CO2 from gaseous IP and 8.7 times of efficiency in removing aqueous DCB in compare with Degussa P25. In this In2O3/TiO2 composite system, TiO2 seems to be the principal photocatalyst whereas the function of In2O3 is to sensitize TiO2 by absorbing visible light (??????420?nm). The extraordinary high photocatalytic efficiency of this composite In2O3/TiO2 under visible light has been explained on the basis of relative energy band positions of the component semiconductors. 相似文献
873.
Chakraborty I Udayabhaskararao T Pradeep T 《Chemical communications (Cambridge, England)》2012,48(54):6788-6790
We report the first high temperature solution state synthesis of glutathione (-SG) protected atomically precise silver clusters. Noble metal cluster synthesis from metal ions generally requires ice cold temperatures as they are extremely sensitive and high temperature routes are used only for core reduction methods, starting from nanoparticles. The clusters formed by the new route have distinct features in their absorption profile and they exhibit red luminescence. They are characterised by other spectroscopic and microscopic techniques and a tentative formula of Ag(75)(SG)(40) has been assigned. 相似文献
874.
T. Chakraborty B.C. Giri 《Applied Mathematical Modelling》2012,36(2):712-722
In this article, we develop an imperfect economic manufacturing quantity (EMQ) model for an unreliable production system subject to process deterioration, machine breakdown and repair and buffer stock. The basic model is developed under general process shift, machine breakdown and repair time distributions. We suggest a computational algorithm for determination of the optimal safety stock and production run time which minimize the expected cost per unit time in the steady state. For a numerical example, we illustrate the outcome of the proposed model and perform a sensitivity analysis with respect to the model-parameters which have direct influence on the optimal decisions. 相似文献
875.
Several matrix methods have been developed for studying polarization properties of light. Jones was the first to apply the matrix method to the study of polarization optics. In Jones matrix formalism the polarized wave field is represented by 2-element column matrix known as Jones Vector and the polarization device encountered by light is represented by a 2×2 matrix, known as the characteristic Jones matrix of the device. Mueller introduced a new matrix method where the wave field is represented by a 4-dimensional vector. The elements of the vector are the Stokes parameters of the beam. In Mueller matrix formalism the optical device is represented by a 4×4 real matrix known as ‘Mueller Matrix’ of the device. The use of coherency matrix also proves to the useful in the study of partially polarized light. Pauli spin matrices have been used to unify the different matrix treatments of polarization optical phenomena. The present article is an attempt to unify the analysis of polarization phenomena using Dirac matrices used by Dirac in quantum mechanics. We have however redefined the set of Dirac matrices in terms of the Kronecher product of Pauli spin matrices. 相似文献
876.
Shuvendu Chakraborty Ujjal Debnath 《International Journal of Theoretical Physics》2010,49(8):1693-1698
We have considered N-dimensional Einstein field equations in which four-dimensional space-time is described by a FRW metric and that of extra
dimensions by an Euclidean metric. We have supposed that the higher dimensional anisotropic universe is filled with only normal
scalar field or tachyonic field. Here we have found the nature of potential of normal scalar field or tachyonic field. From
graphical representations, we have seen that the potential is always decreases with field φ increases. 相似文献
877.
M. Muthu Rama Krishnan Pratik Shah Mousumi Pal Chandan Chakraborty Ranjan Rashmi Paul Jyotirmoy Chatterjee Ajoy K. Ray 《Micron (Oxford, England : 1993)》2010,41(4):312-320
This article presents a quantitative approach for the characterization of normal oral mucosa (NOM) in respect to thickness and textural properties of its entire epithelial layer. Histological images of oral mucosa depict that both thickness and tissue architecture at cellular and tissue level undergo change, as mucosa converts from normal to precancerous or cancerous state. In this study the thickness and fractal dimension of the mucosal epithelium of NOM and oral sub-mucous fibrosis (OSF) condition have been computed using 83 normal and 29 OSF images of oral mucosa. The result shows significant delineation between NOM and OSF in respect of both the epithelial thickness (in μm) and fractal dimensions. This quantitative characterization of oral epithelium will be of immense help for oral onco-pathologists and researchers to assess the biological nature of normal and diseased (OSF) mucosa with higher accuracy. Moreover, further differential applications may enable them to find out newer accurate quantitative diagnostic procedures to that of the usual histopathological gold standard for the assessment of malignant potentiality. 相似文献
878.
879.
880.
Chakraborty A Chakrabarty D Seth D Hazra P Sarkar N 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2006,63(3):594-602
The photo-induced electron transfer between Coumarin dyes and aromatic amines has been investigated using steady state and time-resolved fluorescence quenching studies. We have observed a Marcus type inversion in the electron transfer rate in correlation of quenching constant to the free energy change occurred during reaction. To justify the "inverted region" obtained in the correlation of quenching constant versus free energy curve, we have performed anisotropy measurement and estimated the several diffusional parameters. The translational diffusion coefficients exhibit a similar picture like electron transfer rate constant when it is plotted against free energy. Thus we argued that the diffusion has played an important role in the electron transfer kinetics. 相似文献