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1.
Some properties of cosmological models with a time variable bulk viscous coefficient in the presence of adiabatic matter creation and variable G, c, are investigated in the framework of a specifically flat FRW line element. We trivially find a set of solutions through Dimensional Analysis. In all the studied cases it is found that the behaviour of these "constants" is inversely proportional to the cosmic time. It is found that with the solution obtained our model verifies the principles of general covariance and Lorentz invariance. Finally we emphasize that the envisaged models are free of the horizon and entropy problem.  相似文献   

2.
Particular solutions to the Einstein equations with cosmological constant are presented and discussed for an isotropic, spatially homogeneous, and spatially flat space-time in the case that the matter fields are 4, 6, and sine-Gordon fields.  相似文献   

3.
A rotation, scaling, and translation invariant local watermarking is proposed with one or two Krawtchouk moment(s) of the original to estimate the geometric distortion parameters including rotation angle, scaling factor, and translation parameter. Krawtchouk moments can be used as private key of watermark extractor. Watermark is inserted into perceptually significant Krawtchouk moments of original, and watermark based on Krawtchouk moments is local. Independent component analysis (ICA) is utilized to extract watermark blindly. Experimental results show that this method has a good robustness against distortions preformed by watermark benchmark—Stirmark.  相似文献   

4.
We study the cumulants and their generating functions of the probability distributions of the conductance, shot noise and Wigner delay time in ballistic quantum dots. Our approach is based on the integrable theory of certain matrix integrals and applies to all the symmetry classes ${\beta \in \{1, 2, 4\}}$ of Random Matrix Theory. We compute the weak localization corrections to the mixed cumulants of the conductance and shot noise for β = 1, 4, thus proving a number of conjectures of Khoruzhenko et al. (in Phys Rev B 80:(12)125301, 2009). We derive differential equations that characterize the cumulant generating functions for all ${\beta \in \{1, 2, 4 \} }$ . Furthermore, when β = 2 we show that the cumulant generating function of the Wigner delay time can be expressed in terms of the Painlevé III′ transcendant. This allows us to study properties of the cumulants of the Wigner delay time in the asymptotic limit ${n \to \infty}$ . Finally, for all the symmetry classes and for any number of open channels, we derive a set of recurrence relations that are very efficient for computing cumulants at all orders.  相似文献   

5.
First-principles calculations were performed to investigate the magnetic properties of Zn(Mn,Li)O based on the Perdew-Burke-Ernzerhof form of generalized gradient approximation. Antiferromagnetic (AFM) ordering is the ground state in Mn-doped ZnO system without the codopant of Li, while seven different geometrical configurations of Zn(Mn,Li)O prefer stable ferromagnetic (FM) ordering. We found that dopant Li can effectively change the magnetic coupling in the ZnMnO system. The Curie temperature (TC) of FM ordering depends on the geometric configuration, and the highest TC is about 1388 K. The FM stabilization is greatly affected by Mn-Mn distance rather than by the position of dopant Li. We propose that dopant Li mediates FM coupling through a double exchange interaction or an RKKY interaction when Li is located, respectively, near or far from Mn ions.  相似文献   

6.
We present the electrical resistivity measurements of equiatomic RPt compounds, with R  La, Pr, Nd, Gd, Tb, Dy, Ho and Er, which crystallize into two different orthorhombic structures. The different contributions to the total resistivity were separated. From the phonon contribution ϱp we estimated the Debye temperature θD of the different compounds. Except for GdPt, the increase of the magnetic resistivity above Tc arise from crystal field effects which are larger than those calculated in the point charge model. The paramagnetic Curie temperature and the saturated magnetic resistivity follow approximately the de Gennes law and allowed us to estimate effective mass and the exchange constant through the series.  相似文献   

7.
Molecular Diversity - In the present study, we report the design and synthesis of novel amide-type hybrid molecules based on anthranilic acid and quinoline or β-carboline heterocyclic...  相似文献   

8.
《Physics letters. A》2001,278(4):184-190
We present results of computer simulations of the diffusion-limited reaction process A+B→0, on the line, under extreme drift conditions, for lattices of up to 227 sites, and where the process proceeds to completion (no particles left). These enormous simulations are made possible by the renormalized reaction-cell method (RRC). Our results allow us to resolve an existing controversy about the rate of growth of domain sizes, and about corrections to scaling of the concentration decay.  相似文献   

9.
Mesoporous silicas with chemically attached macrocyclic moieties were successfully prepared by sol-gel condensation of tetraethyl orthosilicate and β-cyclodextrin-silane in the presence of a structure-directing agent. Introduction of β-cyclodextrin groups into the silica framework was confirmed by the results of IR spectral, thermogravimetric, and quantitative chemical analysis of surface compounds. The porous structure of the obtained materials was characterized by nitrogen adsorption-desorption measurements, powder X-ray diffraction, transmission electron microscopy, and dynamic light scattering. It was found that the composition of the reaction mixture used in β-cyclodextrin-silane synthesis significantly affects the structural parameters of the resulting silicas. The increase in (3-aminopropyl)triethoxysilane as well as the coupling agent content in relation to β-cyclodextrin leads ultimately to the lowering or complete loss of hexagonal arrangement of pore channels in the synthesized materials. Formation of hexagonally ordered mesoporous structure was observed at molar composition of the mixture 0.049 TEOS:0.001 β-CD-silane:0.007 CTMAB:0.27 NH4OH:7.2 H2O and equimolar ratio of components in β-CD-silane synthesis. The sorption of alizarin yellow on starting silica and synthesized materials with chemically attached β-cyclodextrin moieties was studied in phosphate buffer solutions with pH 7.0. Experimental results of the dye equilibrium sorption were analyzed using Langmuir, Freundlich, and Redlich-Peterson isotherm models. It was proved that the Redlich-Peterson isotherm model is the most appropriate for fitting the equilibrium sorption of alizarin yellow on parent silica with hexagonally arranged mesoporous structure as well as on modified one with chemically immobilized β-cyclodextrin groups.
Graphical abstract
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10.
In this study, hyperspectral images were used to detect a fungal disease in apple leaves called Marssonina blotch(AMB). Estimation models were built to classify healthy, asymptomatic and symptomatic classes using partial least squares regression(PLSR), principal component analysis(PCA), and linear discriminant analysis(LDA) multivariate methods. In general, the LDA estimation model performed the best among the three models in detecting AMB asymptomatic pixels, while all the models were able to detect the symptomatic class. LDA correctly classified asymptomatic pixels and LDA model predicted them with an accuracy of 88.0%. An accuracy of 91.4% was achieved as the total classification accuracy. The results from this work indicate the potential of using the LDA estimation model to identify asymptomatic pixels on leaves infected by AMB.  相似文献   

11.

We consider a semilinear heat equation with exponential nonlinearity in ?2. We prove that local solutions do not exist for certain data in the Orlicz space exp L 2(?2), even though a small data global existence result holds in the same space exp L 2(?2). Moreover, some suitable subclass of exp L 2(?2) for local existence and uniqueness is proposed.

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12.
Ground-state properties of C, O, and Ne isotopes are described in the framework of Hartree-Fock-Bogoliubov theory with density-dependent finite-range Gogny interaction D1S. We include all the contributions to the Hartree-Fock and pairing feld arising from Gogny and Coulomb interaction as well as the center of mass correction in the numerical calcu/ations. These ground-state properties of C, O, and Ne isotopes are compared with available experimental results, Hartree-Fock plus BCS, shell model and relativistic Hartree--Bogoliubov calculations. The agreement between experiments and our theoretical results is pretty well. The predicted drip-line is dependent strongly on the model and effective interaction due to their sensitivity to various theoretical details. The calculations predict no evidence for halo structure predicted for C,O, and Ne isotopes in a previous RHB study.  相似文献   

13.
The dependences of the cohesive (atomization) energy on the interatomic distance for elements Al, Cu, Ti(A2), V, Mg, Ti(A3), Si, and Sn are calculated using methods based on the Thomas-Fermi-Dirac-Gambosh statistical atomic theory. The obtained dependences are approximated by the Mie-Grüneisen potential. The phonon spectra calculated on the basis of the Born-Kärmän model and the Born-Kärmän-Blackman-de Lunay approach are used to determine the temperature dependences of the specific heat, free energy, and internal energy of the elements under investigation. The calculated cohesive energy, equilibrium interatomic distances, and temperature dependences of the specific heat agree with the experimental data.  相似文献   

14.
15.
In this paper, the relationship between network synchronizability and the edge-addition of its associated graph is investigated. First, it is shown that adding one edge to a cycle definitely decreases the network synchronizability. Then, since sometimes the synchronizability can be enhanced by changing the network structure, the question of whether the networks with more edges are easier to synchronize is addressed. Based on a subgraph and complementary graph method, it is shown by examples that the answer is negative even if the network structure is arbitrarily optimized. This reveals that generally there are redundant edges in a network, which not only make no contributions to synchronization but actually may reduce the synchronizability. Moreover, a simple example shows that the node betweenness centrality is not always a good indicator for the network synchronizability. Finally, some more examples are presented to illustrate how the network synchronizability varies following the addition of edges, where all the examples show that the network synchronizability globally increases but locally fluctuates as the number of added edges increases.  相似文献   

16.
We calculate the cross section of inclusive direct J/ψ hadroproduction at next-to-leading order within the factorization formalism of nonrelativistic quantum chromodynamics, including the full relativistic corrections due to the intermediate 1S(0)[8], 3S(1)[8], and 3P(J)[8] color-octet states. We perform a combined fit of the color-octet long-distance matrix elements to the transverse-momentum (p(T)) distributions measured by CDF at the Fermilab Tevatron and H1 at DESY HERA and demonstrate that they also successfully describe the p(T) distributions from PHENIX at BNL RHIC and CMS at the CERN LHC as well as the photon-proton c.m. energy and (with worse agreement) the inelasticity distributions from H1. This provides a first rigorous test of nonrelativistic QCD factorization at next-to-leading order. In all experiments, the color-octet processes are shown to be indispensable.  相似文献   

17.
18.
This article describes a conservative synchronized remap algorithm applicable to arbitrary Lagrangian–Eulerian computations with nodal finite elements. In the proposed approach, ideas derived from flux-corrected transport (FCT) methods are extended to conservative remap. Unique to the proposed method is the direct incorporation of the geometric conservation law (GCL) in the resulting numerical scheme. It is shown here that the geometric conservation law allows the method to inherit the positivity preserving and local extrema diminishing (LED) properties typical of FCT schemes. The proposed framework is extended to the systems of equations that typically arise in meteorological and compressible flow computations. The proposed algorithm remaps the vector fields associated with these problems by means of a synchronized strategy. The present paper also complements and extends the work of the second author on nodal-based methods for shock hydrodynamics, delivering a fully integrated suite of Lagrangian/remap algorithms for computations of compressible materials under extreme load conditions. Extensive testing in one, two, and three dimensions shows that the method is robust and accurate under typical computational scenarios.  相似文献   

19.
Polycarbonate track detector Makrofol, sensitive to fragments withA16 was used to register products of interactions of 6.3 GeV deuterons with Th, Bi, Au, and Ag. Cross sections for the production of events with one, two and three fragments have been determined and their variation as a function of theZ 2/A of the target analyzed. Possible mechanisms were proposed and discussed. Geometric characteristics of binary events were used in order to identify those binary events which resulted from the process of fission. The results were compared with corresponding proton data.We are grateful to Profs. A. M. Baldin and I. N. Semenyuskin for the exposure of the detectors and for measurement of the flux. We are also thankful to the technical staff of our Laboratory for accurate measurements.  相似文献   

20.
The effects of microstructure, cell orientation and temperature on magnetic properties and the coercivity mechanism in Sm(Co,Fe,Cu,Zr)z with low Cu content are studied by using the micromagnetic finite element method in this paper. The simulations of the demagnetization behaviours indicate that the pinning effect weakens gradually with the thickness of cell boundary decreasing and strengthens gradually with the cell size decreasing. Because of the intergrain exchange coupling, the coercivity mechanism is determined by the difference in magnetocrystalline anisotropy between the cell phase and the cell boundary phase. And the coercivity mechanism is related to not only the cells alignment but also temperature. With temperature increasing, a transformation of the demagnetization mechanism occurs from the domain pinning to the uniform magnetization reversal mode and the transformation temperature is about 650~K.  相似文献   

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