Non-gravitational Fields Research Articles

An axially symmetric scalar field and teleparallelism

An axially symmetric scalar field is considered in teleparallel gravity. We calculate, respectively, the tensor, the vector and the axial-vector parts of torsion and energy, momentum and angular momentum in the ASSF. We find the vector parts are in the radial and $\hat{e}_{\theta}$ directions, the axial-vector, momentum and angular momentum vanish identically, but the energy distribution is different from zero. The vanishing axial-vector part of torsion gives us the result that there occurs no deviation in the spherical symmetry of the spacetime. Consequently, there exists no inertia field with respect to a Dirac particle, and the spin vector of a Dirac particle becomes constant. The result for the energy is the same as obtained by Radinschi. Next, this work also (a) supports the viewpoint of Lessner that the Moller energy-momentum complex is a powerful concept for the energy-momentum, (b) sustains the importance of the energy-momentum definitions in the evaluation of the energy distribution of a given spacetime, and (c) supports the hypothesis by Cooperstock that the energy is confined to the region of non-vanishing energy-momentum tensor of the matter and all non-gravitational fields.

Numerical Simulation of Liquid Metal Free-surface Flows in the Presence of a Uniform Static Magnetic Field

Three-dimensional numerical simulations with a new-developed modeling of two-phase flow have been carried out for free-surface flows of an electric conducting fluid in the presence of a uniform static magnetic field. In this study, several examples such as collapsing liquid column, oscillating droplet in a non-gravitational field and falling droplet in a gravitational field are presented. The driving mechanisms of the flow in these problems are the gravity and the surface tension. The numerical results reveal that the induced electromagnetic force acts to dampen the electric conducting fluid flow efficiently when a uniform vertical magnetic field is applied while it acts to enforce a tendency of two-dimensional flow when a uniform horizontal magnetic field is applied.

Numerical Computation on Magnetothermal Air Jet in Gravitational and Nongravitational Fields

Two-dimensional numerical computations were carried out in order to elucidate the effect of a Kelvin force on the air in two coaxial circular pipes with open ends under both gravitational and nongravitational fields. The outer pipe with open ends corresponds to the bore space of the superconducting magnet. The inner pipe with open ends is assumed to be placed inside this bore space. The sidewall of the outer pipe is cooled isothermally. The central region of the inner pipe is heated isothermally and the other region is thermally insulated. The magnetic gradient that was produced by the electric current circulating within the circular electric coil was applied to air in two coaxial circular pipes with a thermal gradient. Moreover, the present numerical computations were carried out by changing the relative positions of the circular electric coil and the inner pipe. In both gravitational and nongravitational fields, when the circular electric coil was placed at the end of the heated region of the inner pipe, the Kelvin force was produced in the inner pipe and the magnetothermal air jet was created. As a result, the hotter air rapidly flowed out from the end of the inner pipe. These phenomena could be successfully explained by considering the temperature dependence of the mass magnetic susceptibility of air according to Curie's law.

Numerical computation of magnetothermal convection of water in a vertical cylindrical enclosure

Numerical computations were carried out to clarify the effect of Kelvin force on the flow of water in a vertical cylindrical enclosure heated from below and cooled from above under a vertical magnetic field gradient. Since the Kelvin force that is produced by the magnetic field gradient depends on the position and the size of a circular electric coil, the coil was placed at either the hot or the cold plate and the coil diameter was set to be 2.5 or 5 times that of the enclosure. First, to understand the mechanism of the generation of the magnetothermal convection induced by the Kelvin force alone, the transition of velocity and temperature fields were visualized under a non-gravitational field. Under a gravitational field, the average Nusselt number decreased with increase of magnetic strength when the coil was placed at the lower end plate which was heated isothermally so that the generation of natural convection was suppressed by the Kelvin force. On the contrary, the average Nusselt number increased with increase of magnetic strength when the coil was placed at the upper end plate which was cooled isothermally so that the natural convection was enhanced by the Kelvin force.

HEAT TRANSFER CONTROL IN QUIESCENT AIR WITH THERMAL GRADIENT BY MAGNETIZING FORCE UNDER BOTH GRAVITATIONAL AND NONGRAVITATIONAL FIELDS

ABSTRACT Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force on quiescent air with thermal gradient in a vertical cylindrical container under both gravitational and nongravitational fields. Several sizes and axial positions of a circular electric coil were tested so that the magnetizing force depended on the magnetic gradient. Under both gravitational and nongravitational fields, the convection was induced in quiescent air with thermal gradient by the magnetizing force; however, flow pattern and Nusselt number depended strongly on the size and the axial position of the circular electric coil in addition to the magnetic strength.

Aerial flow in a vertical cylindrical container with thermal gradient under a vertical magnetic field

This study focuses on how magnetising force affects the convection of air in a vertical cylindrical container with thermal and magnetic field gradients in non-gravitational and gravitational fields. The model systems with three different thermal boundary conditions are considered in the present work and numerical computations were carried out by changing the relative location of an electric coil and container. In a non-gravitational field, the aerial flow was induced by the magnetising force. On the other hand, in a gravitational field, the air was driven by both gravitational and magnetising forces. In both fields, flow pattern and heat transfer rate greatly depended on the axial location of the electric coil. Under the specific numerical condition, the pulsating flow was observed by the coupling of gravitational and magnetising forces. These phenomena could be successfully explained by visualising the field of magnetising force and considering the mass magnetic susceptibility of air according to Curie's law.

Numerical Prediction on Heat Transfer Phenomenon in Paramagnetic and Diamagnetic Fluids Under a Vertical Magnetic Field Gradient

Two-dimensional numerical computations were carried out in order to clarify the effect of magnetic field on paramagnetic and diamagnetic fluids in a vertical cylindrical container with thermal and vertical magnetic field gradients under both gravitational and nongravitational fields. In both gravitational and nongravitational fields, the magnetizing force that was produced by the gradient of magnetic field could be utilized to control the heat transfer rate for paramagnetic and diamagnetic fluids. These phenomena could be successfully explained by visualizing the field of magnetizing force.

A Possible Modification of Einstein's Theory of General Relativity

This article suggests a new metric theory of gravitation, in which metric field is determined not only by matter and nongravitational field but also by vector graviton field, and in principle there is no need to introduce the Einstein's tensor. In order to satisfy automatically the geodesic postulate, an additional coordinate condition is needed. For the spherically symmetric static field, it leads us to quite different conclusions from those of Einstein's general relativity in the interior region of the surface of infinite redshift. Accurate to the first order of , it obtains the same results about the four experimental tests of general relativity.

B231 磁化力による無重力場中の空気の熱伝達制御

Two-dimensional numerical computations were carried out to clarify the influence of magnetizing force for the heat transfer of air in a vertical cylindrical container with the thermal and vertical magnetic field gradients under a non-gravitational field. In these numerical computations, several sizes and locations of a circular electric coil were tested. In a non-gravitational field, the heat transfer of air was able to be controlled by the magnetizing force. The Nusselt number in a non-gravitational field was increased in comparison with that in a gravitational field.

Numerical computation on the control of aerial flow by the magnetizing force in gravitational and nongravitational fields

Two-dimensional numerical computations were carried out in order to examine the effect of magnetizing force for the air in a cylindrical container with thermal and magnetic field gradients. In a gravitational field, the air was driven by both gravitational and magnetizing forces, and flow pattern and the heat transfer rate greatly depended on the axial position of the coil. Moreover, when the magnetizing and gravitational forces cancel out each other, convection became almost quiescent. On the other hand, the aerial flow was induced by the magnetizing force even in a nongravitational field, and the air behaved like an electrically conducting fluid.

On Generalized Relativistic Billiards in External Force Fields

In this Letter, we study generalized relativistic billiards: as a particle reflects from the boundary of the domain, its velocity is transformed as if the particle underwent an elastic collision with a moving wall, considered within the framework of the special theory of relativity. Inside the domain, the particle moves under the influence of some gravitational and nongravitational force fields.

Pre-big bang in M-theory

We discuss a simple cosmological model derived from M-theory. Threeassumptions lead naturally to a pre-big bangscenario: (a) 11-dimensional supergravity describes thelow-energy world;(b) non-gravitational fields live on a three-dimensional brane; and(c) asymptotically past triviality.

Gravity, Inertia, and Quantum Vacuum Zero Point Fields

Over the past several years Haisch, Rueda, and others have made the claim that the origin of inertial reaction forces can be explained as the interaction of electrically charged elementary particles with the vacuum electromagnetic zero-point field expected on the basis of quantum field theory. After pointing out that this claim, in light of the fact that the inertial masses of the hadrons reside in the electrically chargeless, photon-like gluons that bind their constituent quarks, is untenable, the question of the role of quantum zero-point fields generally in the origin of inertia is explored. It is shown that, although non-gravitational zero-point fields might be the cause of the gravitational properties of normal matter, the action of non-gravitational zero-point fields cannot be the cause of inertial reaction forces. The gravitational origin of inertial reaction forces is then briefly revisited. Recent claims critical of the gravitational origin of inertial reaction forces by Haisch and his collaborators are then shown to be without merit.

Motion Estimation and Capturing of Tumbling Object in Non-Gravitational Field

For repairing broken-down satellites or removing space debris, capturing of tumbling objects in space can be said one of the important technologies in future space activities. This paper proposes a novel capturing method that the chaser adjusts its attitude motion to the target's one before grasping it. This method can solve the problem that the manipulator alone can not grasp a target with large or complicated rotational motion. Several required techniques are discussed, such as motion estimation, attitude control, and modifying chaser's structure, etc. The feasibility is demonstrated by some computer simulations.

Conservation Laws and Symmetry Properties of a Class of Higher Order Theories of Gravity

We consider a class of fourth order theories of gravity with arbitrary matter fields arising from a diffeomorphism invariant Lagrangian density \(\mathcal{L}_T = \mathcal{L}_G + \mathcal{L}_M\), with \(\mathcal{L}_G = \sqrt { - g} \left[ {R + h\left( R \right)} \right]\)and \(\mathcal{L}_M\)the phenomenological representation of the nongravitational fields. We derive first the generalization of the Einstein pseudotensor and the von Freud superpotential. We then show, using the arbitrariness that is always present in the choice of pseudotensor and superpotential, that we can choose these superpotentials to have the same form as those for the Hilbert Lagrangian of general relativity (GR). In particular we may introduce the Moller superpotential of GR as associated with a double-index differential conservation law. Similarly, using the Moller superpotential we prove that we can choose the Komar vector of GR to construct a conserved quantity for isolated asymptotically flat systems. For the example R + R2theory we prove then, that the active mass is equal to the total energy (or inertial mass) of the system.

THE WHEELER-DEWITT EQUATION FOR THE HETEROTIC SUPERSTRING THEORY INCLUDING TERMS QUARTIC IN THE RIEMANN TENSOR

The Wheeler-DeWitt equation for the wave function of the Universe Ψ can be derived for the heterotic superstring, after reduction of the effective action, including terms [Formula: see text] quartic in the Riemann tensor, from ten dimensions to [Formula: see text] dimensions, where [Formula: see text]. If the compactified space is Ricci flat, then no terms ℛ3 appear, since the coefficient of [Formula: see text] in the ten-dimensional action vanishes. The reduced Lagrangian, ignoring all non-gravitational fields, is then L=(16πG)−1R+a2ℛ2+a4α′2ℛ4, where G is the Newton gravitational constant, α′ is the Regge slope parameter, and a2 and a4 are dimensionless coefficients. Including only the first two terms, in the Friedmann space-time ds2=dt2−e2α(t)dx2, leads to the Schrödinger equation i∂Ψ/∂t=[−AMe−Mα∂2/∂ξ2+ VM,K(α, ξ)]Ψ, where AM is a positive constant, ξ≡dα/dt and K is the curvature of the M-space dx2. After the Wick rotation [Formula: see text], this equation becomes [Formula: see text], where [Formula: see text]. The requirement that both V and [Formula: see text] are positive semi-definite leads to the conditions M=3, K=0, which state that space is three-dimensional and flat. Here, a more complete Schrödinger equation is derived, via a perturbative treatment of the terms a4α′2ℛ4, which lifts the degeneracy of the potential V3,0 under Wick rotations, the Lorentzian signature being energetically favoured over the Euclidean signature. This corroborates results concerning supersymmetry and the quantum mechanical consistency of the string theory on the world sheet, for which the Lorentzian signature is also necessary, as it is argued to be for the Feynman path-integral formulation of Ψ.

A class of nonmetric couplings to gravity.

A class of generically nonmetric couplings between nongravitational fields and the gravitational field is introduced. It is shown that these couplings violate the weak equivalence principle at a level (a priori) smaller than the current E\"otv\"os-type experimental limits.

多孔質中空糸膜による液体中の気泡分離

The separation of bubbles in the water/oil was tried using a hydrophobic PTFE/hydrophilic PVA membrane modules. The PTFE membrane was effective to recover the bubbles flowing the outside the fiber in the water into the fiber when inside of fiber was evacuated. The recovery rate, i. e. the gas permeation rate, depended on the gas flow rate, the length of fiber and the degree of vacuum. The recovery ratio which was defined by the recovery rate/the gas flow rate had a good correlation with the gas hold up. On the other hand, the bubbles in the oil were flowing up outside the fiber without any contact to the fiber, and only the oil containing no bubbles was recovered inside the fiber for PTFE membranes. From the results mentioned above this recovery method of bubbles would be available in the nongravitational field such as space station.

Cosmological consequences of a rolling homogeneous scalar field.

The cosmological consequences of a pervasive, rolling, self-interacting, homogeneous scalar field are investigated. A number of models in which the energy density of the scalar field red-shifts in a specific manner are studied. In these models the current epoch is chosen to be scalar-field dominated to agree with dynamical estimates of the density parameter, ${\ensuremath{\Omega}}_{\mathrm{dyn}\mathrm{\ensuremath{\sim}}0.2}$, and zero spatial curvature. The required scalar-field potential is ``nonlinear'' and decreases in magnitude as the value of the scalar field increases. A special solution of the field equations which is an attractive, time-dependent, fixed point is presented. These models are consistent with the classical tests of gravitation theory. The E\otv\os-Dicke measurements strongly constrain the coupling of the scalar field to light (nongravitational) fields. Nucleosynthesis proceeds as in the standard hot big-bang model. In linear perturbation theory the behavior of baryonic perturbations, in the baryon-dominated epoch, do not differ significantly from the canonical scenario, while the presence of a substantial amount of homogeneous scalar-field energy density at low red-shifts inhibits the growth of perturbations in the baryonic fluid. The energy density in the scalar field is not appreciably perturbed by nonrelativistic gravitational fields, either in the radiation-dominated, matter-dominated, or scalar-field-dominated epochs. On the basis of this effect, we argue that these models could reconcile the low dynamical estimates of the mean mass density with the negligibly small spatial curvature preferred by inflation.

Quasi-riemannian theories of gravitation in more than four dimensions

We explore the possibility that in N > 4 spacetime dimensions, gravitation is described by a theory based on a modified Principle of Equivalence, according to which the field equations in locally inertial frames obey a “tangent space” group G T other than the Lorentz group O( N − 1, 1). It is found that such theories are severely restricted by the requirement that G T have a subgroup which acts on four inertial coordinates as O(3,1) and leaves the others invariant. Theories of this sort can have chiral fermions in four dimensions even without non-gravitational gauhe fields.