14,228 research outputs found
Applications Technology Satellite and Communications Technology Satellite user experiments for 1967-1980 reference book. Volume 4: Abstracts
The important user experiments conducted during the fourteen year period from 1966 to 1980 are summarized. A description of each of the satellites and a brief summary of each user experiment is presented. A cross index of user experiments sorted by various parameters and a listing of keywords versus experiment number is included. The experiments are grouped by type of service offered; for example, education, health services, and data transmission. A bibliography of reports by accession number and by author is also presented. User viewpoints of the systems are presented
Applications Technology Satellite and Communications Technology Satellite user experiments for 1967 - 1980 reference book, volume 1
A description of each of the satellites is given and a brief summary of each user experiment is presented. A Cross Index of User Experiments sorted by various parameters and a listing of keywords versus Experiment Number are presented
Reverse graded relaxed buffers for high Ge content SiGe virtual substrates
An innovative approach is proposed for epitaxial growth of high Ge content, relaxed Si1−xGex buffer layers on a Si(001) substrate. The advantages of the technique are demonstrated by growing such structures via chemical vapor deposition and their characterization. Relaxed Ge is first grown on the substrate followed by the reverse grading approach to reach a final buffer composition of 0.78. The optimized buffer structure is only 2.8 µm thick and demonstrates a low surface threading dislocation density of 4×106 cm−2, with a surface roughness of 2.6 nm. The buffers demonstrate a relaxation of up to 107%
Topological Phase Transitions and Holonomies in the Dimer Model
We demonstrate that the classical dimer model defined on a toroidal hexagonal
lattice acquires holonomy phases in the thermodynamic limit. When all
activities are equal the lattice sizes must be considered mod 6 in which case
the finite size corrections to the bulk partition function correspond to a
massless Dirac Fermion in the presence of a flat connection with nontrivial
holonomy. For general bond activities we find that the phase transition in this
model is a topological one, where the torus degenerates and its modular
parameter becomes real at the critical temperature. We argue that these
features are generic to bipartite dimer models and we present a more general
lattice whose continuum partition function is that of a massive Dirac Fermion.Comment: 7 pages, 4 figures. Minor corrections with additional figure
Relaxation of strained silicon on Si0.5Ge0.5 virtual substrates
Strain relaxation has been studied in tensile strained silicon layers grown on Si0.5Ge0.5 virtual substrates, for layers many times the critical thickness, using high resolution x-ray diffraction. Layers up to 30 nm thick were found to relax less than 2% by the glide of preexisting 60° dislocations. Relaxation is limited because many of these dislocations dissociate into extended stacking faults that impede the dislocation glide. For thicker layers, nucleated microtwins were observed, which significantly increased relaxation to 14%. All these tensile strained layers are found to be much more stable than layers with comparable compressive strain
Multi-particle Correlations in Quaternionic Quantum Systems
We investigate the outcomes of measurements on correlated, few-body quantum
systems described by a quaternionic quantum mechanics that allows for regions
of quaternionic curvature. We find that a multi-particle interferometry
experiment using a correlated system of four nonrelativistic, spin-half
particles has the potential to detect the presence of quaternionic curvature.
Two-body systems, however, are shown to give predictions identical to those of
standard quantum mechanics when relative angles are used in the construction of
the operators corresponding to measurements of particle spin components.Comment: REVTeX 3.0, 16 pages, no figures, UM-P-94/54, RCHEP-94/1
Evaluation of thermal data for geologic applications
Sensitivity studies using thermal models indicated sources of errors in the determination of thermal inertia from HCMM data. Apparent thermal inertia, with only simple atmospheric radiance corrections to the measured surface temperature, would be sufficient for most operational requirements for surface thermal inertia. Thermal data does have additional information about the nature of surface material that is not available in visible and near infrared reflectance data. Color composites of daytime temperature, nighttime temperature, and albedo were often more useful than thermal inertia images alone for discrimination of lithologic boundaries. A modeling study, using the annual heating cycle, indicated the feasibility of looking for geologic features buried under as much as a meter of alluvial material. The spatial resolution of HCMM data is a major limiting factor in the usefulness of the data for geologic applications. Future thermal infrared satellite sensors should provide spatial resolution comparable to that of the LANDSAT data
Assessment of methods of acquiring analyzing, and reporting crop production statistics, volume 4
There are no author-identified significant results in this report
Continuation of the compendium of applications technology satellite and communications technology satellite user experiments 1967-1977, volume 2
Approximately 453 reports, papers, and articles catalogued into an information retrieval system, covering communications experiments and demonstrations conducted, utilizing the Communications Technology Satellite and the Applications Technology Satellites 1, 3, 5, and 6 are listed
Calculation of the average Green's function of electrons in a stochastic medium via higher-dimensional bosonization
The disorder averaged single-particle Green's function of electrons subject
to a time-dependent random potential with long-range spatial correlations is
calculated by means of bosonization in arbitrary dimensions. For static
disorder our method is equivalent with conventional perturbation theory based
on the lowest order Born approximation. For dynamic disorder, however, we
obtain a new non-perturbative expression for the average Green's function.
Bosonization also provides a solid microscopic basis for the description of the
quantum dynamics of an interacting many-body system via an effective stochastic
model with Gaussian probability distribution.Comment: RevTex, no figure
- …