On the elastic fields produced by non-uniformly moving dislocations: a revisit

We investigate the non-uniform motion of straight dislocations in infinite media using the theory of incompatible elastodynamics. The equations of motion are derived for non-uniformly moving screw dislocations, gliding edge and climbing edge dislocations. The exact closed-form solutions of the elastic fields are calculated. The fields of the elastic velocity and elastic distortion surrounding the arbitrarily moving dislocations are given explicitly in the form of integral representations free of non-integrable singularities. The elastic fields describe the response in the form of non-uniformly moving elastic waves caused by the motion of the dislocation.     

A Universal Regulator?

By using the principle of metrical invariance which requires that all physical laws are independent of the choice of units (alternatively, all physical laws are invariant with respect to scale transformations of space-time coordinates) and Goldstone's theorem, a universal regulator is discovered. The cosmic field is the Yang-Mills field of the local scale transformations. Its physical role is as follows. Cosmon, its quantum, is a massless, spinless, and neutral particle. The cosmic field is created by inertial masses. Therefore it participates in all physical processes and if its presence is taken into account, then the quantum field theory is free from all ultraviolet infinities. From the point of view of Yang-Mills field theory, it is proved that the so-called gravitational masses are identical with inertial masses and the gravitational field is created by inertial masses moving non-inertially. This fact permits to solve satisfactorily the problem of energy-momentum complex of the gravitational field. The system of equations which defines simultaneously the cosmic and gravitational fields is established. A non-Einstein cosmology is outlined.     

A New Class of Bianchi Type-I Cosmological Models in Lyra Geometry

This paper deals with Bianchi type-V cosmological models of the universe filled with a bulk viscous cosmic fluid in the framework of general relativity. A new class of exact solutions has been obtained by considering various well established power law relations among scale factor, cosmological and gravitational constants and cosmic time. Some physical and geometrical behaviors of the models have also been discussed. It has been found that all the models are in fair agreement of observational results.     

The gauge theory of dislocations: A nonuniformly moving screw dislocation

We investigate the nonuniform motion of a straight screw dislocation in infinite media in the framework of the translational gauge theory of dislocations. The equations of motion are derived for an arbitrarily moving screw dislocation. The fields of the elastic velocity, elastic distortion, dislocation density and dislocation current surrounding the arbitrarily moving screw dislocation are derived explicitly in the form of integral representations. We calculate the radiation fields and the fields depending on the dislocation velocities.     

NMR in well logging and hydrocarbon exploration

Nuclear magnetic resonance (NMR) has become a versatile tool for the evaluation of underground hydrocarbon reservoirs. Formation attributes such as rock porosity and rock pore size distributions, as well as the relative concentrations of water, oil and gas, can be inferred from subsurface NMR. The hydrogen NMR signal encodes porosity as amplitude, pore sizes as relaxation times and fluid properties as a mixture of relaxation and diffusion rates. The paper describes the basic operating principles for NMR on cable (wireline), NMR on a drill string (logging-while-drilling) and NMR for downhole fluid sampling. The geometry of the borehole requires a magnet that projects its field into the surrounding rock, implying a grossly inhomogeneous field distribution. Experience shows that even under these circumstances, saturation-recovery and Carr-Purcell-Meiboom-Gill sequences can work well and yield meaningfulT ₁ andT ₂ information.     

Bulk Viscous Bianchi Type-V Cosmological Models with Variable Gravitational and Cosmological Constant

This paper deals with Bianchi type-V cosmological models of the universe filled with a bulk viscous cosmic fluid in the framework of general relativity. A new class of exact solutions has been obtained by considering various well established power law relations among scale factor, cosmological and gravitational constants and cosmic time. Some physical and geometrical behaviors of the models have also been discussed. It has been found that all the models are in fair agreement of observational results.     

含气孔裂隙地层的声波测井响应特征

本文以径向分层的孔、裂隙地层多极子井孔声场理论为基础,利用孔、裂隙介质弹性波动统一理论,数值模拟了井壁上有侵入时,单极和偶极声源激发的井孔声场随原状地层含气饱和度变化的特征和规律。结果表明：当原状地层裂隙发育时,相较于饱含水,饱含气时纵波幅度衰减严重,横波波至提前,波幅增大,斯通利波幅度变化不明显,低频时弯曲波到时提前,幅度增大;当原状地层裂隙不发育时,单极子、偶极子波形都对流体性质没有明显响应。可见,原状地层中裂隙的存在加剧了含气对纵波、横波的幅度以及到时的影响,而侵入带的存在使得斯通利波和高频弯曲波对原状地层流体性质变化不敏感。数值计算结果为利用声波响应特征识别致密气层提供了参考。     

利用磁共振技术检测钻井液含油量的方法探讨

含油气的岩层被钻开以后,其中的油气一部分保留在岩样中,另一部分则进入钻井液,岩样中的油、气及钻井液中的气都有相应的录井方法来检测,唯独钻井液中的油一直是录井检测的空白. 随着油气勘探程度的加深及钻井工艺技术的发展,岩屑含油级别低甚至无显示、气测异常幅度低甚至无异常的油井是越来越多,导致油气层的发现与评价变得十分困难. 因此,急需对钻井液中的含油量进行随钻检测. 通过对不同油质、 不同含油量的钻井液进行磁共振试验,结果表明,可以通过核磁共振一维谱(T₂谱)实现轻～中质油的含油量分析,通过二维谱(T₂-D谱)以实现对重质油的含油量分析. 该项研究对于完善录井技术系列、提高油层发现率和评价准确率具有十分重要的意义.     

On the Material Invariant Formulation of Maxwell’s Displacement Current

Maxwell accounted for the apparent elastic behavior of the electromagnetic field by augmenting Ampere’s law with the so-called displacement current, in much the same way that he treated the viscoelasticity of gases. Maxwell’s original constitutive relations for both electrodynamics and fluid dynamics were not material invariant. In the theory of viscoelastic fluids, the situation was later corrected by Oldroyd, who introduced the upper-convective derivative. Assuming that the electromagnetic field should follow the general requirements for a material field, we show that if the upper convected derivative is used in place of the partial time derivative in the displacement current term, Maxwell’s electrodynamics becomes material invariant. Note, that the material invariance of Faraday’s law is automatically established if the Lorentz force is admitted as an integral part of the model. The new formulation ensures that the equation for conservation of charge is also material invariant in vacuo. The viscoelastic medium whose apparent manifestation are the known phenomena of electrodynamics is called here the metacontinuum.     

General relativity in Newtonian form

It is shown how the use of coordinates where time is measured with clocks moving radially in a spherically symmetric gravitational field leads to general relativistic dynamical expressions that are exactly identical to corresponding expressions in Newtonian theory. The general formalism is developed for the case where the stress-energy tensor is that of a perfect fluid. Expressions like the Newtonian inverse square gravitational law, the Newtonian equation of continuity for fluid flow, Newtonian conservation of energy, etc., follow quite naturally from the fully-fledged exact general relativistic equations. Specific examples involving cosmology and gravitational collapse are given.     

含物质纯重力场部分贡献的静态和稳态重力场研究

给出了包含重力场贡献在内具有宇宙因子项最普遍形式的重力场方程为Rμν-gμνR/2+λgμν=8πG(T(Ⅰ)μν+T(Ⅱ)μν)/c4，这里λ为Einstein宇宙常数，Ｔ（Ⅰ）μν，Ｔ（Ⅱ）μν分别代表物质纯物质部分和纯重力场部分的能量-动量张量.物质纯重力场部分的能量-动量张量表述为T(Ⅱ)μν=(DμρＤρν-gμνＤαβＤαβ/4)/4πG，式中Dμν的定义为Ｄμν＝ωμ／xν-ων／xμ，ωμ≡-c2gμ0/g00.并用重力场贡献在内最普遍形式的重力场方程分别研究了几个大家所熟悉的静态和稳态重力场，像带有Einstein宇宙因子λ项球对称纯物质球外部静态度规、静态荷电球外部度规、匀速转动星体外部度规及理想纯物质星体内部静态平衡等,并进行了讨论. 关键词： 能量动量张量 重力场方程 静态重力场 稳态重力场     

Cosmic inflation and cosmic string

We discuss the evolution of inhomogeneous space-time with a spinning fluid in higher dimensions. Using these evolving solutions, we explain cosmic inflation and the formation of a gravitational nontopological cosmic string.     

Dynamics of the Chaplygin ball on a rotating plane

This paper addresses the problem of the Chaplygin ball rolling on a horizontal plane which rotates with constant angular velocity. In this case, the equations of motion admit area integrals, an integral of squared angular momentum and the Jacobi integral, which is a generalization of the energy integral, and possess an invariant measure. After reduction the problem reduces to investigating a three-dimensional Poincaré map that preserves phase volume (with density defined by the invariant measure). We show that in the general case the system’s dynamics is chaotic.     

Three-dimensional phase field microelasticity theory of a multivoid multicrack system in an elastically anisotropic body: Model and computer simulations

The phase field microelasticity theory of a three-dimensional, elastically anisotropic system of voids and cracks is proposed. The theory is based on the equation for the strain energy of the continuous elastically homogeneous body presented as a functional of the phase field, which is the effective stress-free strain. It is proved that the stress-free strain minimizing the strain energy of this homogeneous modulus body fully determines the elastic strain and displacement of the body with voids and/or cracks. The proposed phase field integral equation describing the elasticity of an arbitrary system of voids and cracks is exact. The geometry and evolution of multiple voids and/or cracks are described by the phase field, which is the solution of the time-dependent Ginzburg-Landau equation. Other defects, such as dislocations and precipitates, are trivially integrated into this theory. The proposed model does not impose a priori constraints on possible void and crack configurations or their evolution paths. Examples of computations of elastic equilibrium of systems with voids and/or cracks and the evolution of cracks under applied stress are considered.     

Two-Fluid Anisotropic Cosmological Model with Variable G and Λ

Two-fluid anisotropic Bianchi type-III cosmological model is investigated with variable gravitational constant G and cosmological constant Λ in the framework of Einstein’s general relativity. In the two-fluid model, one fluid represents the matter content of the universe and another fluid is chosen to model the cosmic microwave background radiation. The dynamics of the anisotropic universe with variable G and Λ are discussed. We also discussed in detail the behavior of associated fluid parameters and kinematical parameters.     

Cosmic microwave background anisotropy induced by a moving straight cosmic string

A method of searching for cosmic strings based on an analysis of the cosmic microwave background (CMB) anisotropy is presented. A moving straight cosmic string is shown to generate structures of enhanced and reduced brightness with a distinctive shape. The conditions under which a string can be detected by both CMB anisotropy and gravitational lensing in optical surveys are analyzed. For a relativistic string with a deficit angle of ～1″–2″, the amplitude of the generated anisotropy is shown to be ～15–30 μK.     

油基钻井液条件下油层的NMR判识方法

油基钻井液具有润滑性好、抑制性强等特点,有利于井壁稳定和油气层保护,在非常规油气水平井及深井、超深井中广泛使用．但是,油基钻井液具有较强的荧光背景和全烃基值,岩屑难以洗出本色,地层油与钻井液的基础油融合,给油层的识别和评价带来了严重影响．为此,创新采用高分辨率低场核磁共振技术随钻监测钻井液含油率及含油性的变化．室内实验结果表明,油基钻井液不同于混油钻井液,后者属于水包油体系,钻遇油层后,在钻井液T₂谱上出现新峰;而前者属于油包水体系,钻遇油层后,在钻井液T₂谱上不出现新峰,但可通过含油性的变化识别重质油层,通过含油率的变化识别轻-中质油层,并在S903H井全油基钻井液及极端的地质条件下取得了较好的应用效果,证明了钻井液核磁共振是油基钻井液条件下一项有效的油层识别技术．     

Anisotropic hubble expansion of large scale structures

With the aim of understanding the cosmic velocity fields at large scale, we investigate the dynamics of a pressureless distribution of gravitational sources moving under an anisotropic generalization of Hubble expansion and according to Euler-Poisson equations system. As a result, it turns out that such a behavior requires the distribution to be homogenous, similarly to Hubble law. Among several solutions, we show a planar kinematics which admits a constant (eternal) and rotational distortion, where the velocity field is not potential. Within this class, the one with no rotational distortion identifies to a bulk flow. To apply this model within cosmic structures as the Local Super Cluster, the solutions are interpreted as approximations providing us with an hint on the behavior of the cosmic flow just after decoupling era up to present date. Such a result suggests that the observed bulk flow may not be due exclusively to tidal forces but has a primordial origin. UPRES EA 2596. Unité Mixte de Recherche (UMR 6207) du CNRS, et des universités Aix-Marseille I, Aix-Marseille II et du Sud Toulon-Var. Laboratoire affiliéà la FRUMAM (FR 2291).     

Stoneley wave generation by an external seismic point source in an infinite fluid-filled borehole embedded in a transversely isotropic formation: Basic relationships

The method of integral transformations is used to obtain a long-wave solution to the problem of tube wave excitation by an external point source in an infinite fluid-filled borehole embedded in a transversely isotropic formation. The external field that occurs in the formation gives rise to waves in the borehole fluid. The waves generated in the borehole include the lowest mode of the Stoneley wave (tube wave), which is the borehole eigenmode, and the qP-and qSV-waves. It is shown that the Stoneley wave is determined by the contributions of two poles in the complex plane of horizontal slowness. According to the asymptotic solution, the Stoneley wave can be described by one of three different waveforms depending on the relationship between the elastic parameters of the surrounding anisotropic formation and the borehole fluid. An analysis of the results of calculations shows that the shape and polarity of the Stoneley wave strongly depend on the sign of the nonellipticity parameter of the elastic medium, which offers a possibility of estimating the anisotropy of the borehole environment from observations of the waveform of the Stoneley wave.