62,003 research outputs found
User's Guide for ERB 7 Matrix. Volume 1: Experiment Description and Quality Control Report for Year 1
The Nimbus 7 ERB MATRIX Tape is a computer program in which radiances and irradiances are converted into fluxes which are used to compute the basic scientific output parameters, emitted flux, albedo, and net radiation. They are spatially averaged and presented as time averages over one-day, six-day, and monthly periods. MATRIX data for the period November 16, 1978 through October 31, 1979 are presented. Described are the Earth Radiation Budget experiment, the Science Quality Control Report, Items checked by the MATRIX Science Quality Control Program, and Science Quality Control Data Analysis Report. Additional material from the detailed scientific quality control of the tapes which may be very useful to a user of the MATRIX tapes is included. Known errors and data problems and some suggestions on how to use the data for further climatologic and atmospheric physics studies are also discussed
Effect of stoichiometry on oxygen incorporation in MgB2 thin films
The amount of oxygen incorporated into MgB2 thin films upon exposure to
atmospheric gasses is found to depend strongly on the material's stoichiometry.
Rutherford backscattering spectroscopy was used to monitor changes in oxygen
incorporation resulting from exposure to: (a) ambient atmosphere, (b) humid
atmospheres, (c) anneals in air and (d) anneals in oxygen. The study
investigated thin-film samples with compositions that were systematically
varied from Mg0.9B2 to Mg1.1B2. A significant surface oxygen contamination was
observed in all of these films. The oxygen content in the bulk of the film, on
the other hand, increased significantly only in Mg rich films and in films
exposed to humid atmospheres.Comment: 10 pages, 6 figures, 1 tabl
Magnetic control assembly qualification model
Fabrication and testing of the magnetic control assembly (MCA) are summarized. The MCA was designed as an add-on unit for certain existing components of the Nimbus and ERTS attitude control system. The MCA system consists of three orthogonal electromagnets; a magnetometer probe capable of sensing external fields in the X, Y, and Z axes; and the control electronics. An operational description of the system is given along with all major drawings and photographs. Manufacturing and inspection procedures are outlined and a chronological list of events is included with the fabrication summary
Oscillation Phenomena in the disk around the massive black hole Sagittarius A*
We report the detection of radio QPOs with structure changes using the Very
Long Baseline Array (VLBA) at 43 GHz. We found conspicuous patterned changes of
the structure with P = 16.8 +- 1.4, 22.2 +- 1.4, 31.2 +- 1.5, 56.4 +- 6 min,
very roughly in a 3:4:6:10 ratio. The first two periods show a rotating one-arm
structure, while the P = 31.4 min shows a rotating 3-arm structure, as if
viewed edge-on. At the central 50 microasec the P = 56.4 min period shows a
double amplitude variation of those in its surroundings. Spatial distributions
of the oscillation periods suggest that the disk of SgrA* is roughly edge-on,
rotating around an axis with PA = -10 degree. Presumably, the observed VLBI
images of SgrA* at 43 GHz retain several features of the black hole accretion
disk of SgrA* in spite of being obscured and broadened by scattering of
surrounding plasma.Comment: 24 pages, 20 figures, revised version submitted to MN main journal
(2010, Jan., 12th
Symmetry of the Gap in Bi2212 from Photoemission Spectroscopy
In a recent Letter, Shen et al have detected a large anisotropy of the
superconducting gap in Bi2212, consistent with d-wave symmetry, from
photoemission spectroscopy. Moreover, they claim that the change in their
spectra as a function of aging is also consistent with such an intrepretation.
In this Comment, I show that the latter statement is not entirely correct, in
that the data as a function of aging are inconsistent with a d-wave gap but are
consistent with an anisotropic s-wave gap.Comment: 3 pages (Plain TeX with macros), plus 1 postscript figur
Resolvent Estimates in L^p for the Stokes Operator in Lipschitz Domains
We establish the resolvent estimates for the Stokes operator in
Lipschitz domains in , for . The result, in particular, implies that the Stokes operator in a
three-dimensional Lipschitz domain generates a bounded analytic semigroup in
for (3/2)-\varep < p< 3+\epsilon. This gives an affirmative answer to a
conjecture of M. Taylor.Comment: 28 page. Minor revision was made regarding the definition of the
Stokes operator in Lipschitz domain
Modeling of a Cantilever-Based Near-Field Scanning Microwave Microscope
We present a detailed modeling and characterization of our scalable microwave
nanoprobe, which is a micro-fabricated cantilever-based scanning microwave
probe with separated excitation and sensing electrodes. Using finite-element
analysis, the tip-sample interaction is modeled as small impedance changes
between the tip electrode and the ground at our working frequencies near 1GHz.
The equivalent lumped elements of the cantilever can be determined by
transmission line simulation of the matching network, which routes the
cantilever signals to 50 Ohm feed lines. In the microwave electronics, the
background common-mode signal is cancelled before the amplifier stage so that
high sensitivity (below 1 atto-Farad capacitance changes) is obtained.
Experimental characterization of the microwave probes was performed on
ion-implanted Si wafers and patterned semiconductor samples. Pure electrical or
topographical signals can be realized using different reflection modes of the
probe.Comment: 7 figure
Quantum quench dynamics of the Bose-Hubbard model at finite temperatures
We study quench dynamics of the Bose-Hubbard model by exact diagonalization.
Initially the system is at thermal equilibrium and of a finite temperature. The
system is then quenched by changing the on-site interaction strength
suddenly. Both the single-quench and double-quench scenarios are considered. In
the former case, the time-averaged density matrix and the real-time evolution
are investigated. It is found that though the system thermalizes only in a very
narrow range of the quenched value of , it does equilibrate or relax well in
a much larger range. Most importantly, it is proven that this is guaranteed for
some typical observables in the thermodynamic limit. In order to test whether
it is possible to distinguish the unitarily evolving density matrix from the
time-averaged (thus time-independent), fully decoherenced density matrix, a
second quench is considered. It turns out that the answer is affirmative or
negative according to the intermediate value of is zero or not.Comment: preprint, 20 pages, 7 figure
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