Gravitational field of an expanding spherically symmetric shell in RTG. Linear velocity approximation

The appearance of nonstatic behavior of the gravitational fieldof an expanding, spherically symmetric shell is shown in RTG under the linear velocity approximation for a gravitational field of arbitrary magnitude.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 108, No. 1, pp. 79–83. July, 1996.     

Basic aspects of geopotential field approximation from satellite‐to‐satellite tracking data

The satellite‐to‐satellite tracking (SST) problems are characterized from mathematical point of view. Uniqueness results are formulated. Moreover, the basic relations are developed between (scalar) approximation of the earth's gravitational potential by ‘scalar basis systems’ and (vectorial) approximation of the gravitational field by ‘vectorial basis systems’. Finally, the mathematical justification is given for approximating the external geopotential field by finite linear combinations of certain gradient fields (for example, gradient fields of multi‐poles) consistent to a given set of SST data. Copyright © 2001 John Wiley & Sons, Ltd.     

Regions of prevalence in the coupled restricted three-body problems approximation

This work concerns the role played by a couple of the planar circular restricted three-body problem in the approximation of the bicircular model. The comparison between the differential equations governing the dynamics leads to the definition of region of prevalence where one restricted model provides the best approximation of the four-body model. According to this prevalence, the patched three-body problem approximation is used to design first guess trajectories for a spacecraft travelling under the Sun-Earth-Moon gravitational influence.     

引力的曲率平方理论

利用法坐标对局部等效原理、以及局部等效原理在构造曲率平方可重整拉氏量中的作用进行了论证．得到了曲率平方引力的场方程、其线性近似以及有质引力粒子的Ｙｕｋａｗａ势的表式．     

Gravitational field of a massive rotating spherical shell in RTG

We obtain a continuous solution describing the gravitational field of a massive rotating shell in the relativistic theory of gravity (RTG) in an approximation linear in expansion rate but arbitrary in the magnitude of the static gravitational field. We show that the coordinate-invariant dragging effect inside the shell may be used to define a global inertial coordinate system.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 106, No. 2, pp. 315–319, February, 1996.     

Is the Causality Principle Violated for Gravitational Waves?

We verify the causality principle for the relativistic theory of gravity in the linear approximation. We show that the contribution of weak gravitational waves is considerably less than the contributions of the static part of the solution and the cosmological background. Therefore, the presence of weak gravitational waves does not violate the causality principle for the relativistic theory of gravity.     

Post-Newtonian approximation in the relativistic theory of gravity

Based on the RTG equations, a simple derivation of the post-Newtonian approximation is presented. A comparison is made of the calculations of gravitational effects in the solar system based on RTG and on the general theory of relativity.Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 105, No. 1, pp. 163–174, October, 1995.     

A Nash–Hörmander iteration and boundary elements for the Molodensky problem

We investigate the numerical approximation of the nonlinear Molodensky problem, which reconstructs the surface of the earth from the gravitational potential and the gravity vector. The method, based on a smoothed Nash–Hörmander iteration, solves a sequence of exterior oblique Robin problems and uses a regularization based on a higher-order heat equation to overcome the loss of derivatives in the surface update. In particular, we obtain a quantitative a priori estimate for the error after $m$ steps, justify the use of smoothing operators based on the heat equation, and comment on the accurate evaluation of the Hessian of the gravitational potential on the surface, using a representation in terms of a hypersingular integral. A boundary element method is used to solve the exterior problem. Numerical results compare the error between the approximation and the exact solution in a model problem.     

On a Computational Model of Gravitational Hydrodynamics with Consideration of Radiation Transfer in the Diffusion Approximation Using Tetrahedral Meshes

Journal of Applied and Industrial Mathematics - We propose some new computational model of gravitational hydrodynamics with consideration of radiation transfer in diffusion approximation on...     

Approximation of the capillarity problem by an augmented lagrangian method

We propose an algorithm to compute an approximation of capillary surfaces in a gravitational field. This algorithm is based on a decomposition-coordination method by augmented lagrangians and the discretization is done using the finite element method. We study the convergence of the algorithm and the error of discretization for the axisymmetric case; some numerical results are given. This method can be generalized to a two-dimensional space.Projet IDOPT (CNRS-UJF-INPG-INRIA).     

Rotations of a near-symmetrical satellite in an elliptical orbit with Mercury-type resonance

The motion of a satellite, i.e., a rigid body, about to the centre of mass under the action of the gravitational moments of a central Newtonian gravitational field in an elliptical orbit of arbitrary eccentricity is investigated. It is assumed that the satellite is almost dynamically symmetrical. Plane periodic motions for which the ratio of the average value of the absolute angular velocity of the satellite to the average motion of its centre of mass is equal to 3/2 (Mercury-type resonance) are examined. An analytic solution of the non-linear problem of the existence of such motions and their stability to plane perturbations is given. In the special case in which the central ellipsoid of inertia of the satellite is almost spherical, the stability to spatial perturbations is also examined, but only in a linear approximation. ©2008.     

Gauge Dependence of the Effective Gravitational Field

We analyze the gauge ambiguity problem for the effective gravitational field from the standpoint of the measurement process. The motion of a test point particle playing the role of a measuring device is investigated in the field of a point gravitating mass in the one-loop approximation. We show that the gravitational field value determined from the effective equations of motion of the device explicitly depends on the Feynman gauge parameter. This dependence is essential in the sense that a gauge variation cannot be interpreted as a deformation of the reference frame, which leads to a gauge ambiguity in the values of observed quantities. In particular, this result disproves the hypothesis that gauge dependence is canceled in the effective equations of motion of a classical point particle.     

Calculating the profile of a multicomponent liquid with the plane-layer geometry

We use the multicomponent liquid system with the spatial restriction in the form of a plane parallel layer. For this system, we calculate the profile of the distribution of densities of different system components in the general form in the approximation of a smooth inhomogeneity under the condition that the external field acts perpendicularly to the layer plane. We investigate the gravitational field case separately. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 151, No. 1, pp. 149–154, April, 2007.     

Wrinkle-free solutions in the theory of annular elastic membranes

Rotationally symmetric deformations of a flat annular elastic membrane under a gravitational force are studied, with prescribed radial stresses or horizontal displacements at the edges. The small-finitedeflection theory of Föppl-Hencky as well as a simplified version of Reissner's static first approximation theory of thin shells of revolution are applied which lead to consider a single, second-order, ordinary differential equation for the derivation of the principal stresses in the membrane. Using analytical methods, the range of those boundary data is determined for which the solutions of the differential equation are wrinkle free in the sense that both the radial and the circumferential stress components are nonnegative everywhere.     

A general hilbert space approach to wavelets and its application in geopotential determination

A general approach to wavelets is presented within a framework of a separable functional Hilbert space H. Basic tool is the construction of H-product kernels by use of Fourier analysis with respect to an orthonormal basis in H. Scaling functions and wavelet are defined in terms of H-product kernels. Wavelts are shown to be ‘building blocks’ that decorrelate the data. A pyramid scheme provides fast computation. Finally, the determination of the earth's gravitational potential from single and multipole expressions is organzied as an example of wavelet approximation in Hilbert space structure.     

On the conditions under which a satellite orbit intersects the surface of a central body of finite radius in the restricted double-averaged three-body problem

This paper is concerned with the applied problem of choosing long-living orbits of artificial Earth satellites whose evolution under the influence of gravitational perturbation from the Moon and the Sun may result in the collision of the satellite with the central body, as was shown by M.L. Lidov for the well-known example of “Vertical Moon.” We use solutions of the completely integrable system of evolution equations obtained by Lidov in 1961 by averaging twice the spatial circular restricted three-body problem in the Hill approximation. In order to apply the integrability of this problem in practice, we study the foliation of the manifold of levels of first integrals and the change of motion under crossing the bifurcation manifolds separating the foliated cells. As a result, we describe the manifold of initial conditions under which the orbit evolution leads to an inevitable collision of the satellite with the central body. We also find a lower bound for the practical applicability of the results, which is determined by the presence of gravitational perturbations caused by a polar flattening of the central body. Original Russian Text ? V.I. Prokhorenko, 2007, published in Trudy Matematicheskogo Instituta imeni V.A. Steklova, 2007, Vol. 259, pp. 156–173.     

The stability of the steady motions of a rigid body in a central field

The problem of the translational-rotational motion of a rigid body with a triaxial ellipsoid of inertia in a central gravitational field is considered. The body is modelled by a weightless sphere, at the ends of the three mutually perpendicular diameters of which there are point masses. It is shown that, unlike the cases when the approximate expression for the potential of the gravity forces is used, there are not only “trivial” steady motions of the body, for which the main central axes of inertia of the body coincide with the axes of the orbital system of coordinates, but also other classes of steady motions. In addition, the stability of these “trivial” steady motions is investigated, and the possibility of secular stability of the motions, unstable in the satellite approximation, is pointed out.     

Holographic instant conformal symmetry breaking by colliding conical defects

We study instant conformal symmetry breaking as a holographic effect of ultrarelativistic particles moving in the AdS₃ space–time. We give a qualitative picture of this effect based on calculating the two-point correlation functions and the entanglement entropy of the corresponding boundary theory. We show that in the geodesic approximation, because of gravitational lensing of the geodesics, the ultrarelativistic massless defect produces a zone structure for correlators with broken conformal invariance. At the same time, the holographic entanglement entropy also exhibits a transition to nonconformal behavior. Two colliding massless defects produce a more diverse zone structure for correlators and the entanglement entropy.     

Post-Newtonian gravitational radiation of a system of two compact objects in the field theory of gravitation

Conclusions Using the general expressions of the field theory of gravitation in the second nonvanishing, post-Newtonian, approximation, we have obtained the expressions (19) and (20) for the intensity of the gravitational radiation L, and also the total energy emitted during a period of elliptic motion of the bodies, E_e (29), and the bremsstrahlung energy E_h (30) for a system of two static spherically symmetric compact bodies. We have shown that the Peters-Mathews coefficients in the field theory are equal to k₁=12, k₂=11, and that there is no dipole radiation: k_L=0. The expressions obtained for L, E_e, and E_h in the post-Newtonian approximation make it possible to compare the predictions of the field theory with the results of observations.Scientific-Research Institute of Nuclear Physics at the Moscow State University. Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 52, No. 3, pp. 414–422, September, 1982.     

On the conditions under which a satellite orbit intersects the surface of a central body of finite radius in the restricted double-averaged three-body problem

This paper is concerned with the applied problem of choosing long-living orbits of artificial Earth satellites whose evolution under the influence of gravitational perturbation from the Moon and the Sun may result in the collision of the satellite with the central body, as was shown by M.L. Lidov for the well-known example of “Vertical Moon.” We use solutions of the completely integrable system of evolution equations obtained by Lidov in 1961 by averaging twice the spatial circular restricted three-body problem in the Hill approximation. In order to apply the integrability of this problem in practice, we study the foliation of the manifold of levels of first integrals and the change of motion under crossing the bifurcation manifolds separating the foliated cells. As a result, we describe the manifold of initial conditions under which the orbit evolution leads to an inevitable collision of the satellite with the central body. We also find a lower bound for the practical applicability of the results, which is determined by the presence of gravitational perturbations caused by a polar flattening of the central body.