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951.
A New Cohomology Theory of Orbifold 总被引:7,自引:0,他引:7
Based on the orbifold string theory model in physics, we construct a new cohomology ring for any almost complex orbifold. The key theorem is the associativity of this new ring. Some examples are computed.Both authors partially supported by the National Science Foundation 相似文献
952.
Gábor Házi 《Central European Journal of Physics》2003,1(3):453-462
A general class of analytical solutions of the lattice Boltzmann equation is derived for two-dimensional, steady-state unidirectional
flows. A subset of the solutions that verifies the corresponding Navier-Stokes equations is given. It is pointed out that
this class includes, e.g., the Couette and the Poiseuille flow but not, e.g., the basic Kolmogorov flow. For steady-state
non-unidirectional flows, first and second order solutions of the lattice Boltzmann equation are derived. Practical consequences of the analysis
are mentioned. Differences between the technique applied here and those used in some earlier works are emphasized. 相似文献
953.
1D-nanostructural zinc oxide (ZnO) with different shapes have been synthesized on p-type Si(1 0 0) and glass substrates via vapor phase growth by heating pure zinc powder at temperatures between 480 and 570 °C. The different ZnO nanostructures depend on the substrates and the growth temperatures. Scanning electron microscopy and X-ray diffraction revealed that a well-aligned nanowires array, which are vertical to the substrate of Si(1 0 0) with 18 sides on their heads, but six sides on their stems, has been formed at 480 °C. Raman study on the ZnO nanostructures shows that the coupling strength between electron and phonon determined by the ratio of the second- to the first-order Raman scattering cross-sections declines with decreasing diameter of the nanowires. However, a little changes of the coupling strength in terms of the width of the nanobelts have been observed. 相似文献
954.
Günter Graumann Prof. Dr. 《ZDM》2005,37(3):190-198
Problem fields with one or two generating problems and possibilities of varying existing problems give a good chance for self-activities of students and can be used for reaching different general aims. In this paper some topics concerning quadrilaterals will be presented. I hope they will animate teachers for more problem orientation in mathematics education. First we will reflect about different types of convex and non-convex quadrilaterals and possibilities of ordering them. Then we focus on middle-quadrilaterals and types of quadrilaterals with special middle-quadrilaterals as well as their logical ordering. Finally we investigate the analogies in space to the parallelogram and its sub-types and order them in the “house of parallelepipeds”. 相似文献
955.
Adrian Vasiu 《Central European Journal of Mathematics》2005,3(1):14-25
We include short and elementary proofs of two theorems that characterize reductive group schemes over a discrete valuation
ring, in a slightly more general context. 相似文献
956.
L. Martinovič 《Few-Body Systems》2005,36(1-4):167-171
We study three problems of the light-front field theory quantized in a finite volume with fields (anti-)periodic in x−: (a) microcausality by deriving an integral representation for the discrete Pauli-Jordan function; (b) surface terms violating Poincaré algebra; (c) a LF version of the Goldstone theorem. The first two problems are resolved by careful mathematical treatment. The third one illustrates the usefulness of DLCQ as an analytical scheme. 相似文献
957.
Data on the proteinase complex from Carica papaya latex were reviewed. The properties and applications of the domestic preparation cucumazyme and known medicinal preparations based on papaya proteinases (caripazyme, lecozyme, lecopain) were compared. 相似文献
958.
M. De Falco F. De Giovanni C. Musella R. Schmidt 《Rendiconti del Circolo Matematico di Palermo》2003,52(1):70-76
A subgroupH of a groupG is said to bepermutable ifHX=XH for every subgroupX ofG. In this paper the structure of groups in which every subgroup either is abelian or permutable is investigated.
This work was done while the last author was visiting the University of Napoli Federico II. He thanks the “Dipartimento di
Matematica e Applicazioni” for its financial support. 相似文献
959.
960.
In this article, we define stochastic dynamics for a system coupled to reservoirs. The rules for forward and backward transitions are related by a generalized detailed balance identity involving the system and its reservoirs. We compare the variation of information and of entropy. We define the Carnot dissipation and prove that it can be expressed in terms of cyclic transformations. Lower bounds for partial dissipations are also studied, as well as the effect of switching off certain reservoirs. We also study the near degeneracy of the stochastic matrix, relate it to phase transitions and we show that the reduced dynamics on the set of phases is a permutation. Finally, we relate these concepts to heat, work and more generally to the dissipation and creation of resources, in general systems. 相似文献