20,148 research outputs found
Nickel-cadmium cell life test
Over 6,9000 Low Earth Orbit cycles were accumulated at 30% Depth of Discharge on twelve INTELSAT-design nickel-hydrogen cells. Physical equipment and cells are described. Performance characteristics are seen to be uniform. Further testing is planned to seek a failure mode, and also to investigate the effects of a new additive for nickel-hydrogen cells. Initial results indicate improved performance at higher temperatures and diminished swelling of positive nickel plates
Phase Space Formulation of Quantum Mechanics. Insight into the Measurement Problem
A phase space mathematical formulation of quantum mechanical processes
accompanied by and ontological interpretation is presented in an axiomatic
form. The problem of quantum measurement, including that of quantum state
filtering, is treated in detail. Unlike standard quantum theory both quantum
and classical measuring device can be accommodated by the present approach to
solve the quantum measurement problemComment: 29 pages, 4 figure
Phase field modeling of electrochemistry II: Kinetics
The kinetic behavior of a phase field model of electrochemistry is explored
for advancing (electrodeposition) and receding (electrodissolution) conditions
in one dimension. We described the equilibrium behavior of this model in [J. E.
Guyer, W. J. Boettinger, J.A. Warren, and G. B. McFadden, ``Phase field
modeling of electrochemistry I: Equilibrium'', cond-mat/0308173]. We examine
the relationship between the parameters of the phase field method and the more
typical parameters of electrochemistry. We demonstrate ohmic conduction in the
electrode and ionic conduction in the electrolyte. We find that, despite making
simple, linear dynamic postulates, we obtain the nonlinear relationship between
current and overpotential predicted by the classical ``Butler-Volmer'' equation
and observed in electrochemical experiments. The charge distribution in the
interfacial double layer changes with the passage of current and, at
sufficiently high currents, we find that the diffusion limited deposition of a
more noble cation leads to alloy deposition with less noble species.Comment: v3: To be published in Phys. Rev. E v2: Attempt to work around
turnpage bug. Replaced color Fig. 4a with grayscale 13 pages, 7 figures in 10
files, REVTeX 4, SIunits.sty, follows cond-mat/030817
Hidden Dirac Monopoles
Dirac showed that the existence of one magnetic pole in the universe could
offer an explanation of the discrete nature of the electric charge. Magnetic
poles appear naturally in most grand unified theories. Their discovery would be
of greatest importance for particle physics and cosmology. The intense
experimental search carried thus far has not met with success. I proposed a
universe with magnetic poles which are not observed free because they hide in
deeply bound monopole--anti-monopole states named monopolium. I discuss the
realization of this proposal and its consistency with known cosmological
features. I furthermore analyze its implications and the experimental
signatures that confirm the scenario.Comment: Comments: 15 pages, 3 figure
Non-analytical power law correction to the Einstein-Hilbert action: gravitational wave propagation
We analyze the features of the Minkowskian limit of a particular
non-analytical f(R) model, whose Taylor expansion in the weak field limit does
not hold, as far as gravitational waves (GWs) are concerned. We solve the
corresponding Einstein equations and we find an explicit expression of the
modified GWs as the sum of two terms, i.e. the standard one and a modified
part. As a result, GWs in this model are not transverse, and their polarization
is different from that of General Relativity. The velocity of the GW modified
part depends crucially on the parameters characterizing the model, and it
mostly results much smaller than the speed of light. Moreover, this
investigation allows one to further test the viability of this particular f(R)
gravity theory as far as interferometric observations of GWs are concerned.Comment: 18 pages, 3 figure
Bubbles created from vacuum fluctuation
We show that the bubbles can be created from vacuum
fluctuation in certain De Sitter universe, so the space-time foam-like
structure might really be constructed from bubbles of in the
very early inflating phase of our universe. But whether such foam-like
structure persisted during the later evolution of the universe is a problem
unsolved now.Comment: 6 page
Building a functional, integrated GIS/remote sensing resource analysis and planning system
To be an effective tool for resource analysis and planning, a geographic information system (GIS) needs to be integrated with a digital remote sensing capability. To be truly functional, the paired system must be driven by grass roots local needs. A case study couched in a Soil Conservation District in northern Utah is presented. Agency representatives determined that the most fundamental data sets to be entered into the GIS system analysis system in the first round were: land use/land cover; geomorphic/soil unit data; hydrologic unit data; and digital terrain. The least expensive and best ways to obtain these data were determined. Data were acquired and formatted to enter the state's PRIME/ARC-INFO GIS, and are being interrogated for resource management decisions related to such issues as agricultural preservation, urban expansion, soil erosion control, and dam siting
Wigner-Yanase skew information as tests for quantum entanglement
A Bell-type inequality is proposed in terms of Wigner-Yanase skew
information, which is quadratic and involves only one local spin observable at
each site. This inequality presents a hierarchic classification of all states
of multipartite quantum systems from separable to fully entangled states, which
is more powerful than the one presented by quadratic Bell inequalities from
two-entangled to fully entangled states. In particular, it is proved that the
inequality provides an exact test to distinguish entangled from nonentangled
pure states of two qubits. Our inequality sheds considerable light on
relationships between quantum entanglement and information theory.Comment: 5 page
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