12,790 research outputs found
Darwin-Lagrangian Analysis for the Interaction of a Point Charge and a Magnet: Considerations Related to the Controversy Regarding the Aharonov-Bohm and Aharonov-Casher Phase Shifts
The classical electromagnetic interaction of a point charge and a magnet is
discussed by first calculating the interaction of point charge with a simple
model magnetic moment and then suggesting a multiparticle limit. The Darwin
Lagrangian is used to analyze the electromagnetic behavior of the model
magnetic moment (composed of two oppositely charged particles of different mass
in an initially circular orbit) interacting with a passing point charge. The
changing mangetic moment is found to put a force back on a passing charge; this
force is of order 1/c^2 and depends upon the magnitude of the magnetic moment.
It is suggested that in the limit of a multiparticle magnetic toroid, the
electric fields of the passing charge are screened out of the body of the
magnet while the magnetic fields penetrate into the magnet. This is consistent
with our understanding of the penetration of electromagnetic velocity fields
into ohmic conductors. Conservation laws are discussed. The work corresponds to
a classical electromagnetic analysis of the interaction which is basic to
understanding the controversy over the Aharonov-Bohm and Aharonov-Casher phase
shifts and represents a refutation of the suggestions of Aharonov, Pearle, and
Vaidman.Comment: 33 page
Hydrodynamic reductions of the heavenly equation
We demonstrate that Pleba\'nski's first heavenly equation decouples in
infinitely many ways into a triple of commuting (1+1)-dimensional systems of
hydrodynamic type which satisfy the Egorov property. Solving these systems by
the generalized hodograph method, one can construct exact solutions of the
heavenly equation parametrized by arbitrary functions of a single variable. We
discuss explicit examples of hydrodynamic reductions associated with the
equations of one-dimensional nonlinear elasticity, linearly degenerate systems
and the equations of associativity.Comment: 14 page
Derivation of the Blackbody Radiation Spectrum from a Natural Maximum-Entropy Principle Involving Casimir Energies and Zero-Point Radiation
By numerical calculation, the Planck spectrum with zero-point radiation is
shown to satisfy a natural maximum-entropy principle whereas alternative
choices of spectra do not. Specifically, if we consider a set of
conducting-walled boxes, each with a partition placed at a different location
in the box, so that across the collection of boxes the partitions are uniformly
spaced across the volume, then the Planck spectrum correspond to that spectrum
of random radiation (having constant energy kT per normal mode at low
frequencies and zero-point energy (1/2)hw per normal mode at high frequencies)
which gives maximum uniformity across the collection of boxes for the radiation
energy per box. The analysis involves Casimir energies and zero-point radiation
which do not usually appear in thermodynamic analyses. For simplicity, the
analysis is presented for waves in one space dimension.Comment: 11 page
Some Heuristic Semiclassical Derivations of the Planck Length, the Hawking Effect and the Unruh Effect
The formulae for Planck length, Hawking temperature and Unruh-Davies
temperature are derived by using only laws of classical physics together with
the Heisenberg principle. Besides, it is shown how the Hawking relation can be
deduced from the Unruh relation by means of the principle of equivalence; the
deep link between Hawking effect and Unruh effect is in this way clarified.Comment: LaTex file, 6 pages, no figure
The Zero-Point Field and Inertia
A brief overview is presented of the basis of the electromagnetic zero-point
field in quantum physics and its representation in stochastic electrodynamics.
Two approaches have led to the proposal that the inertia of matter may be
explained as an electromagnetic reaction force. The first is based on the
modeling of quarks and electrons as Planck oscillators and the method of
Einstein and Hopf to treat the interaction of the zero-point field with such
oscillators. The second approach is based on analysis of the Poynting vector of
the zero-point field in accelerated reference frames. It is possible to derive
both Newton's equation of motion, F=ma, and its relativistic co-variant form
from Maxwell's equations as applied to the zero-point field of the quantum
vacuum. This appears to account, at least in part, for the inertia of matter.Comment: 8 pages, no fig
Generating anisotropic fluids from vacuum Ernst equations
Starting with any stationary axisymmetric vacuum metric, we build anisotropic
fluids. With the help of the Ernst method, the basic equations are derived
together with the expression for the energy-momentum tensor and with the
equation of state compatible with the field equations. The method is presented
by using different coordinate systems: the cylindrical coordinates
and the oblate spheroidal ones. A class of interior solutions matching with
stationary axisymmetric asymptotically flat vacuum solutions is found in oblate
spheroidal coordinates. The solutions presented satisfy the three energy
conditions.Comment: Version published on IJMPD, title changed by the revie
Homogeneous heterotic supergravity solutions with linear dilaton
I construct solutions to the heterotic supergravity BPS-equations on products
of Minkowski space with a non-symmetric coset. All of the bosonic fields are
homogeneous and non-vanishing, the dilaton being a linear function on the
non-compact part of spacetime.Comment: 36 pages; v2 conclusion updated and references adde
EVALUATING BIOLOGICAL AND PHYSICAL DRIVERS OF EVAPOTRANSPIRATION TRENDS AT NORTHEASTERN US WATERSHEDS
MOCVD growth of Bi2Te3-Sb2Te3 layers : Effect of growth parameters on the electrical and thermoelectrical properties
The growth of (Bi1-xSbx)2Te3 thin films by metal-organic chemical vapour deposition (MOCVD) using trimethylbismuth, triethylantimony and diethyltellurium as bismuth, antimony and tellurium sources respectively is investigated on pyrex substrates. The electrical and thermoelectrical properties of this material are also measured over the growth temperature range 360-470°C. The studies are also made on the effect of VI/V ratio on these properties in the variation range 2-9. Polycrystalline structure is confirmed by X-ray diffraction, and it is observed that the intensity of the preferred orientation is higher at 450°C. The measurement of Seebeck coefficient shows that all samples have p-type conduction. The best value of this parameter is obtained for high growth temperature (240µV/K). The good result obtained for (Bi1-xSbx)2Te3 thin films revealed the great potential of MOCVD method which is an industrial technique to produce good materials for device applications (sensors and thermopiles).The growth of (Bi1-xSbx)2Te3 thin films by metal-organic chemical vapour deposition (MOCVD) using trimethylbismuth, triethylantimony and diethyltellurium as bismuth, antimony and tellurium sources respectively is investigated on pyrex substrates. The electrical and thermoelectrical properties of this material are also measured over the growth temperature range 360-470°C. The studies are also made on the effect of VI/V ratio on these properties in the variation range 2-9. Polycrystalline structure is confirmed by X-ray diffraction, and it is observed that the intensity of the preferred orientation is higher at 450°C. The measurement of Seebeck coefficient shows that all samples have p-type conduction. The best value of this parameter is obtained for high growth temperature (240µV/K). The good result obtained for (Bi1-xSbx)2Te3 thin films revealed the great potential of MOCVD method which is an industrial technique to produce good materials for device applications (sensors and thermopiles)
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