4,450 research outputs found
Hydrogen absorption in solid aluminum during high-temperature steam oxidation
Hydrogen is emitted by aluminum heated in a vacuum after high-temperature steam treatment. Wire samples are tested for this effect, showing dependence on surface area. Two different mechanisms of absorption are inferred, and reactions deduced
The hydrogenation of metals upon interaction with water
Hydrogen evolution at 600 deg and 5 x 10 to the 7th power - 10 to the 6th power torr from AVOOO Al samples, which were pickled in 10 percent NaOH, is discussed. An H evolution kinetic equation is derived for samples of equal vol. and different surfaces (5 and 20 sq cm). The values of the H evolution coefficient K indicated an agreement with considered H diffusion mechanism through an oxide layer. The activation energy for the H evolution process, obtained from the K-temp. relation, was 13,000 2000 cal/g-atom
Matter formed at the BNL relativistic heavy ion collider
We suggest that the "new form of matter" found just above by RHIC is
made up of tightly bound quark-antiquark pairs, essentially 32 chirally
restored (more precisely, nearly massless) mesons of the quantum numbers of
, , and . Taking the results of lattice gauge
simulations (LGS) for the color Coulomb potential from the work of the
Bielefeld group and feeding this into a relativistic two-body code, after
modifying the heavy-quark lattice results so as to include the
velocity-velocity interaction, all ground-state eigenvalues of the 32 mesons go
to zero at just as they do from below as predicted by the vector
manifestation (VM in short) of hidden local symmetry. This could explain the
rapid rise in entropy up to found in LGS calculations. We argue that how
the dynamics work can be understood from the behavior of the hard and soft
glue.Comment: Final versio
Troposphere-stratosphere (surface-55 km) monthly general circulation statistics for the Northern Hemisphere-four year averages
This report presents four year averages of monthly mean Northern Hemisphere general circulation statistics for the period from 1 December 1978 through 30 November 1982. Computations start with daily maps of temperature for 18 pressure levels between 1000 and 0.4 mb that were supplied by NOAA/NMC. Geopotential height and geostrophic wind are constructed using the hydrostatic and geostrophic formulae. Fields presented in this report are zonally averaged temperature, mean zonal wind, and amplitude and phase of the planetary waves in geopotential height with zonal wavenumbers 1-3. The northward fluxes of heat and eastward momentum by the standing and transient eddies along with their wavenumber decomposition and Eliassen-Palm flux propagation vectors and divergences by the standing and transient eddies along with their wavenumber decomposition are also given. Large annual and interannual variations are found in each quantity especially in the stratosphere in accordance with the changes in the planetary wave activity. The results are shown both in graphic and tabular form
The Probability Density of the Higgs Boson Mass
The LEP Collaborations have reported a small excess of events in their
combined Higgs boson analysis at center of mass energies up to about 208 GeV.
In this communication, I present the result of a calculation of the probability
distribution function of the Higgs boson mass which can be rigorously obtained
if the validity of the Standard Model is assumed. It arises from the
combination of the most recent set of precision electroweak data and the
current results of the Higgs searches at LEP 2.Comment: 3 pages, 2 figure
Efficient computation of the first passage time distribution of the generalized master equation by steady-state relaxation
The generalized master equation or the equivalent continuous time random walk
equations can be used to compute the macroscopic first passage time
distribution (FPTD) of a complex stochastic system from short-term microscopic
simulation data. The computation of the mean first passage time and additional
low-order FPTD moments can be simplified by directly relating the FPTD moment
generating function to the moments of the local FPTD matrix. This relationship
can be physically interpreted in terms of steady-state relaxation, an extension
of steady-state flow. Moreover, it is amenable to a statistical error analysis
that can be used to significantly increase computational efficiency. The
efficiency improvement can be extended to the FPTD itself by modelling it using
a Gamma distribution or rational function approximation to its Laplace
transform
THERMAL RADIATION FROM MAGNETIZED NEUTRON STARS: A look at the Surface of a Neutron Star.
Surface thermal emission has been detected by ROSAT from four nearby young
neutron stars. Assuming black body emission, the significant pulsations of the
observed light curves can be interpreted as due to large surface temperature
differences produced by the effect of the crustal magnetic field on the flow of
heat from the hot interior toward the cooler surface. However, the energy
dependence of the modulation observed in Geminga is incompatible with blackbody
emission: this effect will give us a strong constraint on models of the neutron
star surface.Comment: 10 pages. tar-compressed and uuencoded postcript file. talk given at
the `Jubilee Gamow Seminar', St. Petersburg, Sept. 1994
Detection of trend changes in time series using Bayesian inference
Change points in time series are perceived as isolated singularities where
two regular trends of a given signal do not match. The detection of such
transitions is of fundamental interest for the understanding of the system's
internal dynamics. In practice observational noise makes it difficult to detect
such change points in time series. In this work we elaborate a Bayesian method
to estimate the location of the singularities and to produce some confidence
intervals. We validate the ability and sensitivity of our inference method by
estimating change points of synthetic data sets. As an application we use our
algorithm to analyze the annual flow volume of the Nile River at Aswan from
1871 to 1970, where we confirm a well-established significant transition point
within the time series.Comment: 9 pages, 12 figures, submitte
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