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21.
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An Approximated Solution of the Einstein Equations for a Rotating Body with Negligible Mass 总被引:1,自引:0,他引:1
A. Tartaglia 《General Relativity and Gravitation》2003,35(3):371-387
The paper considers the problem of finding the metric of space time around a rotating, weakly gravitating body. Both external and internal metric tensors are consistently found, together with an appropriate source tensor. All tensors are calculated at the lowest meaningful approximation in a power series. The two physical parameters entering the equations (the mass and the angular momentum per unit mass) are assumed to be such that the mass effects are negligible with respect to the rotation effects. A non zero Riemann tensor is obtained. The order of magnitude of the physical effects is discussed. 相似文献
23.
We give sufficient conditions for the rigid body in the presence of an axisymmetric force field and a gyroscopic torque to admit a Hamilton-Poisson formulation. Even if by adding a gyroscopic torque we initially lose one of the conserved Casimirs, we recover another conservation law as a Casimir function for a modified Poisson structure. We apply this frame to several well-known results in the literature. 相似文献
24.
We report on free excitons coexisting with exciton magnetic polarons (EMPs) in bulk semimagnetic semiconductors of Cd1−xMnxTe for 0.04?x?0.36 at 2 K under nonresonant two-photon excitation. This two-photon excitation not only generates free excitons but also more efficiently creates EMPs compared with ordinary one-photon excitation. Stimulated emission from free excitons is demonstrated under strong two-photon excitation. 相似文献
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We consider a four-dimensional generalization of Hess–Appel’rot system and costruct its Lax pair. Both classical and algebro-geometric integration procedure are proceeded. The algebro-geometric integration is based on deep facts from geometry of Prym varieties such as the Mumford relation and Mumford-Dalalyan theory. The integration is similar to the integration of Lagrange bitop which has recetly been performed by the authors. 相似文献
27.
《International Journal of Polymer Analysis and Characterization》2012,17(7):424-437
Ultra high molecular weight polyethylene (UHMWPE) is a component of mobile prostheses. The irradiation performed to sterilize and cross-link the polymer limits its life because of the free radicals originated during this process. In this work, a UHMWPE was electron-beam irradiated under high vacuum and annealed. Mechanical tests were performed on the UHMWPE samples before and after the annealing treatment. The results were compared with a study of radical species type and amount and the crystalline degree changes. Experimental results show that the annealing treatment prevents degrading reactions, favors intermolecular and/or intramolecular chemical rearrangements, and improves wear resistance without compromising the typical elasto-plastic mechanical behavior. 相似文献
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The exact expression for the electrostatic interaction between an ionpenetrable sphere and an ion-impenetrable rigid sphere is derived on the basis of the linearized Poisson-Boltzmann equation without recourse to Derjaguin's approximation. 相似文献
30.
Dr. Zhenbo Mo Dr. Takanori Shima Prof. Dr. Zhaomin Hou 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8713-8722
Studies on N2 activation and transformation by transition metal hydride complexes are of particular interest and importance. The synthesis and diverse transformations of a dinitrogen dititanium hydride complex bearing the rigid acridane-based acriPNP-pincer ligands {[(acriPNP)Ti]2(μ2-η1:η2-N2)(μ2-H)2} are presented. This complex enabled N2 cleavage and hydrogenation even without additional H2 or other reducing agents. Furthermore, diverse transformations of the N2 unit with a variety of organometallic compounds such as ZnMe2, MgMe2, AlMe3, B(C6F5)3, PinBH, and PhSiH3 have been well established at the rigid acriPNP-ligated dititanium framework, such as reversible bonding-mode change between the end-on and side-on/end-on fashions, diborylative N=N bond cleavage, the formal insertion of two dimethylaluminum species into the N=N bond, and the formal insertion of two silylene units into the N=N bond. This work has revealed many unprecedented aspects of dinitrogen reaction chemistry. 相似文献