615 research outputs found
Improved Equation for Shear Modulus Using Four-Point Ring-Twist Test Data
There are numerous test-specimen configurations for determining the static shear modulus of composites. Selection of specimen configuration depends primarily on product component configuration. Two-ring specimens in use are the split-ring twist specimen and the four-point-loading ring-twist specimen. The latter is more advantageous, since it uses an intact ring. However, reported validation tests on aluminum rings showed a large error in predicted shear modulus. The present paper provides an improved analysis that takes into account the tilting of the cross section on the loading bar.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline
Massive Electrodynamics and the Magnetic Monopoles
We investigate in detail the problem of constructing magnetic monopole
solutions within the finite-range electrodynamics (i.e., electrodynamics with
non-zero photon mass, which is the simplest extension of the standard theory;
it is fully compatible with the experiment). We first analyze the classical
electrodynamics with the additional terms describing the photon mass and the
magnetic charge; then we look for a solution analogous to the Dirac monopole
solution. Next, we plug the found solution into the Schr\"{o}dinger equation
describing the interaction between the the magnetic charge and the electron.
After that, we try to derive the Dirac quantization condition for our case.
Since gauge invariance is lost in massive electrodynamics, we use the method of
angular momentum algebra. Under rather general assumptions we prove the theorem
that the construction of such an algebra is not possible and therefore the
quantization condition cannot be derived. This points to the conclusion that
the Dirac monopole and the finite photon mass cannot coexist within one and the
same theory. Some physical consequences of this conclusion are considered. The
case of t'Hooft-Polyakov monopole is touched upon briefly.Comment: 24 pages, revtex, 1 figure appended as a PostScript fil
Singularities in the Fermi liquid description of a partially filled Landau level and the energy gaps of fractional quantum Hall states
We consider a two dimensional electron system in an external magnetic field
at and near an even denominator Landau level filling fraction. Using a
fermionic Chern--Simons approach we study the description of the system's low
energy excitations within an extension of Landau's Fermi liquid theory. We
calculate perturbatively the effective mass and the quasi--particle interaction
function characterizing this description. We find that at an even denominator
filling fraction the fermion's effective mass diverges logarithmically at the
Fermi level, and argue that this divergence allows for an {\it exact}
calculation of the energy gaps of the fractional quantized Hall states
asymptotically approaching these filling fractions. We find that the
quasi--particle interaction function approaches a delta function. This singular
behavior leads to a cancelation of the diverging effective mass from the long
wavelength low frequency linear response functions at even denominator filling
fractions.Comment: 46 pages, RevTeX, 5 figures included in a uuencoded postscript file.
Minor revisions relative to the original version. The paper will be published
in the Physical Review B, and can be retrieved from the World Wide Web, in
http://cmtw.harvard.edu/~ster
Surface layering of liquids: The role of surface tension
Recent measurements show that the free surfaces of liquid metals and alloys
are always layered, regardless of composition and surface tension; a result
supported by three decades of simulations and theory. Recent theoretical work
claims, however, that at low enough temperatures the free surfaces of all
liquids should become layered, unless preempted by bulk freezing. Using x-ray
reflectivity and diffuse scattering measurements we show that there is no
observable surface-induced layering in water at T=298 K, thus highlighting a
fundamental difference between dielectric and metallic liquids. The
implications of this result for the question in the title are discussed.Comment: 5 pages, 4 figures, to appear in Phys. Rev. B. 69 (2004
Communicating Josephson Qubits
We propose a scheme to implement a quantum information transfer protocol with
a superconducting circuit and Josephson charge qubits. The information exchange
is mediated by an L-C resonator used as a data bus. The main decoherence
sources are analyzed in detail.Comment: 4 pages, 2 figure
Performances and stability of a 2.4 ton Gd organic liquid scintillator target for antineutrino detection
In this work we report the performances and the chemical and physical
properties of a (2 x 1.2) ton organic liquid scintillator target doped with Gd
up to ~0.1%, and the results of a 2 year long stability survey. In particular
we have monitored the amount of both Gd and primary fluor actually in solution,
the optical and fluorescent properties of the Gd-doped liquid scintillator
(GdLS) and its performances as a neutron detector, namely neutron capture
efficiency and average capture time. The experimental survey is ongoing, the
target being continuously monitored. After two years from the doping time the
performances of the Gd-doped liquid scintillator do not show any hint of
degradation and instability; this conclusion comes both from the laboratory
measurements and from the "in-tank" measurements. This is the largest stable
Gd-doped organic liquid scintillator target ever produced and continuously
operated for a long period
Einstein energy associated with the Friedmann -Robertson -Walker metric
Following Einstein's definition of Lagrangian density and gravitational field
energy density (Einstein, A., Ann. Phys. Lpz., 49, 806 (1916); Einstein, A.,
Phys. Z., 19, 115 (1918); Pauli, W., {\it Theory of Relativity}, B.I.
Publications, Mumbai, 1963, Trans. by G. Field), Tolman derived a general
formula for the total matter plus gravitational field energy () of an
arbitrary system (Tolman, R.C., Phys. Rev., 35(8), 875 (1930); Tolman, R.C.,
{\it Relativity, Thermodynamics & Cosmology}, Clarendon Press, Oxford, 1962));
Xulu, S.S., arXiv:hep-th/0308070 (2003)). For a static isolated system, in
quasi-Cartesian coordinates, this formula leads to the well known result , where is the
determinant of the metric tensor and is the energy momentum tensor of
the {\em matter}. Though in the literature, this is known as "Tolman Mass", it
must be realized that this is essentially "Einstein Mass" because the
underlying pseudo-tensor here is due to Einstein. In fact, Landau -Lifshitz
obtained the same expression for the "inertial mass" of a static isolated
system without using any pseudo-tensor at all and which points to physical
significance and correctness of Einstein Mass (Landau, L.D., and Lifshitz,
E.M., {\it The Classical Theory of Fields}, Pergamon Press, Oxford, 2th ed.,
1962)! For the first time we apply this general formula to find an expression
for for the Friedmann- Robertson -Walker (FRW) metric by using the same
quasi-Cartesian basis. As we analyze this new result, physically, a spatially
flat model having no cosmological constant is suggested. Eventually, it is seen
that conservation of is honoured only in the a static limit.Comment: By mistake a marginally different earlier version was loaded, now the
journal version is uploade
Non-Fermi-liquid behavior in the Kondo lattices induced by peculiarities of magnetic ordering and spin dynamics
A scaling consideration of the Kondo lattices is performed with account of
singularities in the spin excitation spectral function. It is shown that a
non-Fermi-liquid (NFL) behavior between two critical values of the bare
coupling constant occurs naturally for complicated magnetic structures with
several magnon branches. This may explain the fact that a NFL behavior takes
place often in the heavy-fermion systems with peculiar spin dynamics. Another
kind of a NFL-like state (with different critical exponents) can occur for
simple antiferromagnets with account of magnon damping, and for paramagnets,
especially with two-dimensional character of spin fluctuations. The mechanisms
proposed lead to some predictions about behavior of specific heat, resistivity,
magnetic susceptibility, and anisotropy parameter, which can be verified
experimentally.Comment: 16 pages, RevTeX, 4 Postscript figures. Extended versio
Quasi-local Energy for Spherically Symmetric Spacetimes
We present two complementary approaches for determining the reference for the
covariant Hamiltonian boundary term quasi-local energy and test them on
spherically symmetric spacetimes. On the one hand, we isometrically match the
2-surface and extremize the energy. This can be done in two ways, which we call
programs I (without constraint) and II (with additional constraints). On the
other hand, we match the orthonormal 4-frames of the dynamic and the reference
spacetimes. Then, if we further specify the observer by requiring the reference
displacement to be the timelike Killing vector of the reference, the result is
the same as program I, and the energy can be positive, zero, or even negative.
If, instead, we require that the Lie derivatives of the two-area along the
displacement vector in both the dynamic and reference spacetimes to be the
same, the result is the same as program II, and it satisfies the usual
criteria: the energies are non-negative and vanish only for Minkowski (or
anti-de Sitter) spacetime.Comment: 16 pages, no figure
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