排序方式: 共有9条查询结果,搜索用时 15 毫秒
1
1.
Yakov Itin 《General Relativity and Gravitation》1999,31(2):187-203
The wave type field equationa =a, where ais a coframe field on a space-time, was recentlyproposed to describe the gravity field. This equationhas a unique static, spherically symmetric, asymptotically flat solution, whichleads to the viable Yilmaz–Rosen metric. We showthat the wave type field equation is satisfied by thepseudo-conformal frame if the conformal factor isdetermined by a scalar 3D-harmonic function. This functioncan be related to the Newtonian potential of classicalgravity. So we obtain a direct relation between thenon-relativistic gravity and the relativistic model: every classical exact solution leads to asolution of the field equation. With this result weobtain a wide class of exact, static metrics. We showthat the theory of Yilmaz relates to thepseudo-conformal sector of our construction. We derive also aunique cosmological (time dependent) solution of thedescribed type. 相似文献
2.
Ruggiero De Ritis Giuseppe Marmo Bruno Preziosi 《General Relativity and Gravitation》1999,31(10):1501-1517
A free system, considered to be a comparisonsystem, allows for the notion of objective existence andinertial frame. Transformations connecting inertialframes are shown to be either Lorentz or generalizedGalilei. 相似文献
3.
Yakov Itin 《General Relativity and Gravitation》1999,31(12):1891-1911
We have shown recently that the gravity fieldphenomena can be described by a traceless part of thewave-type field equation. This is an essentiallynon-Einsteinian gravity model. It has an exactsphericallysymmetric static solution, that yields to theYilmaz-Rosen metric. This metric is very close to theSchwarzchild metric. The wave-type field equation cannotbe derived from a suitable variational principle by free variations, as was shown by Hehl and hiscollaborators. In the present work we are looking foranother field equation having the same exactspherically-symmetric static solution. Thedifferential-geometric structure on the manifold endowed with a smoothorthonormal coframe field is described by the scalarobjects of anholonomity and its exterior derivative. Weconstruct a list of the first and second order SO(1,3)-covariants (one- and two-indexedquantities) and a quasi-linear field equation with freeparameters. We fix a part of the parameters by acondition that the field equation is satisfied by aquasi-conformal coframe with a harmonic conformal function .Thus we obtain a wide class of field equations with asolution that yields the Majumdar-P apapetrou metricand, in particular, the Yilmaz-Rosen metric, that is viable in the framework of three classicaltests. 相似文献
4.
The main aim of this paper is to develop a mathematical tool for General Relativity (GR). For this purpose useful tensor expressions have been worked out, which considerably ease various calculations using the sequential approximation in Einstein's GR. Based upon these expressions, compact and explicit formulae have been worked out for the covariant and contravariant components of the metric tensor and its determinant. 相似文献
5.
《Quaestiones Mathematicae》2013,36(2):251-262
The main aim of this paper is to find formulae for the computation of the geodesic metric on the Sierpí nski carpet. This is accomplished by introducing carpet coordinates. Subsequently we show the equivalence of the Euclidean and the geodesic metric on this fractal. 相似文献
6.
通过对一个中心仓库和N个零售商的二级分布库存系统进行分析,采用基本(S-1,S)库存策略,综合运用了排队法和M ETR IC近似法,提出了一种在中心仓库有损失销售的二级库存管理模型,该模型描述在中心仓库缺货情况下,多数零售商不等待延期付货,而直接与供应商订货,导致中心仓库就会因损失销售而产生机会成本.该模型可达到二级分布库存系统的总成本最小. 相似文献
7.
Simon Davis 《General Relativity and Gravitation》1998,30(3):345-377
Symmetries of generalized gravitational actions, yielding field equations which typically involve at most second-order derivatives of the metric, are considered. The field equations for several different higher-derivative theories in the first-order formalism are derived, and variations of a generic set of higher-order curvature terms appearing in string effective actions are studied. It is shown that there often exists a particular set of solutions to the field equations of pure gravity theories, consisting of different combinations of curvature tensors, which satisfies the vacuum equations with cosmological constant. Implications of generalized symmetries of the field equations derived from the superstring effective action for the cosmological constant problem are discussed. 相似文献
8.
Hrvoje Nikolic 《General Relativity and Gravitation》1999,31(8):1211-1217
In a nongeometrical interpretation of gravity,the metric g(x) = + (x)is interpreted as an effective metric, whereas(x) is interpreted as afundamental gravitational field, propagated in spacetime which isactually flat. Some advantages and disadvantages of suchan interpretation are discussed. The main advantage isa natural resolution of the flatness problem. 相似文献
9.
We calculate the Einstein and Landau-Lifshitzpseudo-tensors for Kerr-Schild metrics with geodesicnull vector and show that the first of these vanishesidentically but that the second does not. These results correct a statement by Gurses and Gursey whoclaimed that both were zero. We also show that thesub-class of metrics for which both pseudotensors vanishincludes the Kinnersley photon rocket metric for anarbitrarily accelerating point mass. 相似文献
1