7,897 research outputs found
Cobalt improves nickel hydroxide electrodes for batteries
Positive nickel hydroxide electrodes containing 20 mole percent of cobalt hydroxide are more efficient than when impregnated to the same degree by weight with nickel hydroxide alone. Charge-acceptance and oxygen-evolution tests indicate cobalt electrodes are more efficient than plain positive nickel hydroxide electrodes at all rates of charge
Use of LARS system for the quantitative determination of smoke plume lateral diffusion coefficients from ERTS images of Virginia
A technique for measuring smoke plume of large industrial sources observed by satellite using LARSYS is proposed. A Gaussian plume model is described, integrated in the vertical, and inverted to yield a form for the lateral diffusion coefficient, Ky. Given u, wind speed; y sub l, the horizontal distance of a line of constant brightness from the plume symmetry axis a distance x sub l, downstream from reference point at x=x sub 2, y=0, then K sub y = u ((y sub 1) to the 2nd power)/2 x sub 1 1n (x sub 2/x sub 1). The technique is applied to a plume from a power plant at Chester, Virginia, imaged August 31, 1973 by LANDSAT I. The plume bends slightly to the left 4.3 km from the source and estimates yield Ky of 28 sq m/sec near the source, and 19 sq m/sec beyond the bend. Maximum ground concentrations are estimated between 32 and 64 ug/cu m. Existing meteorological data would not explain such concentrations
Ejection Energy of Photoelectrons in Strong Field Ionization
We show that zero ejection energy of the photoelectrons is classically
impossible for hydrogen-like ions, even when field ionization occurs
adiabatically. To prove this we transform the basic equations to those
describing two 2D anharmonic oscillators. The same method yields an alternative
way to derive the anomalous critical field of hydrogen-like ions. The
analytical results are confirmed and illustrated by numerical simulations. PACS
Number: 32.80.RmComment: 7 pages, REVTeX, postscript file including the figures is available
at http://www.physik.th-darmstadt.de/tqe/dieter/publist.html or via anonymous
ftp from ftp://tqe.iap.physik.th-darmstadt.de/pub/dieter/publ_I_pra_pre.ps,
accepted for publication in Phys. Rev.
Boundedness of Pseudodifferential Operators on Banach Function Spaces
We show that if the Hardy-Littlewood maximal operator is bounded on a
separable Banach function space and on its associate space
, then a pseudodifferential operator
is bounded on whenever the symbol belongs to the
H\"ormander class with ,
or to the the Miyachi class
with ,
. This result is applied to the case of
variable Lebesgue spaces .Comment: To appear in a special volume of Operator Theory: Advances and
Applications dedicated to Ant\'onio Ferreira dos Santo
Cosine and Sine Operators Related with Orthogonal Polynomial Sets on the Intervall [-1,1]
The quantization of phase is still an open problem. In the approach of
Susskind and Glogower so called cosine and sine operators play a fundamental
role. Their eigenstates in the Fock representation are related with the
Chebyshev polynomials of the second kind. Here we introduce more general cosine
and sine operators whose eigenfunctions in the Fock basis are related in a
similar way with arbitrary orthogonal polynomial sets on the intervall [-1,1].
To each polynomial set defined in terms of a weight function there corresponds
a pair of cosine and sine operators. Depending on the symmetry of the weight
function we distinguish generalized or extended operators. Their eigenstates
are used to define cosine and sine representations and probability
distributions. We consider also the inverse arccosine and arcsine operators and
use their eigenstates to define cosine-phase and sine-phase distributions,
respectively. Specific, numerical and graphical results are given for the
classical orthogonal polynomials and for particular Fock and coherent states.Comment: 1 tex-file (24 pages), 11 figure
Processing and Transmission of Information
Contains reports on six research projects.Purchase Order DDL-B15
Theory of Exciton Recombination from the Magnetically Induced Wigner Crystal
We study the theory of itinerant-hole photoluminescence of two-dimensional
electron systems in the regime of the magnetically induced Wigner crystal. We
show that the exciton recombination transition develops structure related to
the presence of the Wigner crystal. The form of this structure depends strongly
on the separation between the photo-excited hole and the plane of the
two-dimensional electron gas. When is small compared to the magnetic
length, additional peaks appear in the spectrum due to the recombination of
exciton states with wavevectors equal to the reciprocal lattice vectors of the
crystal. For larger than the magnetic length, the exciton becomes strongly
confined to an interstitial site of the lattice, and the structure in the
spectrum reflects the short-range correlations of the Wigner crystal. We derive
expressions for the energies and the radiative lifetimes of the states
contributing to photoluminescence, and discuss how the results of our analysis
compare with experimental observations.Comment: 10 pages, no figures, uses Revtex and multicol.st
Diffusion in a Random Velocity Field: Spectral Properties of a Non-Hermitian Fokker-Planck Operator
We study spectral properties of the Fokker-Planck operator that describes
particles diffusing in a quenched random velocity field. This random operator
is non-Hermitian and has eigenvalues occupying a finite area in the complex
plane. We calculate the eigenvalue density and averaged one-particle Green's
function, for weak disorder and dimension d>2. We relate our results to the
time-evolution of particle density, and compare them with numerical
simulations.Comment: 4 pages, 2 figure
Solitary Waves of Planar Ferromagnets and the Breakdown of the Spin-Polarized Quantum Hall Effect
A branch of uniformly-propagating solitary waves of planar ferromagnets is
identified. The energy dispersion and structures of the solitary waves are
determined for an isotropic ferromagnet as functions of a conserved momentum.
With increasing momentum, their structure undergoes a transition from a form
ressembling a droplet of spin-waves to a Skyrmion/anti-Skyrmion pair. An
instability to the formation of these solitary waves is shown to provide a
mechanism for the electric field-induced breakdown of the spin-polarized
quantum Hall effect.Comment: 5 pages, 3 eps-figures, revtex with epsf.tex and multicol.st
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