49,635 research outputs found
Design of an atmospheric sounding radiometer for the GOES meteorological satellite system
An advanced version of the visible infrared spin scan radiometer onboard U.S. geostationary operational environmental satellites was developed to add a vertical dimension to the instrument's infrared atmospheric images. Through the addition of twelve selectable narrow band filters and more precise in-flight calibration of the infrared detectors, the VISSR atmospheric sounder (VAS) will provide increased data to help determine the Earth's atmospheric temperature and water vapor distribution. The radiometer design, filter wheel, calibration shutter mechanisms, and their preflight test performance are discussed
Thermal radiation analysis system TRASYS 2: User's manual
The Thermal Radiation Analyzer System (TRASYS) program put thermal radiation analysis on the same basis as thermal analysis using program systems such as MITAS and SINDA. The user is provided the powerful options of writing his own executive, or driver logic and choosing, among several available options, the most desirable solution technique(s) for the problem at hand. This User's Manual serves the twofold purpose of instructing the user in all applications and providing a convenient reference book that presents the features and capabilities in a concise, easy-to-find manner
Thermal radiation analysis system (TRASYS)
The Thermal Radiation Analysis System, TRASYS, is a digital computer software system with generalized capability to solve the radiation-related aspects of thermal analysis problems. When used in conjunction with a generalized thermal analyzer program any thermal problem that can be expressed in terms of a lumped parameter R-C thermal network can be solved. The function of TRASYS is twofold. It provides: (1) internode radiation interchange data; and (2) incident and absorbed heat rate data from environmental radiant heat sources. Data of both types is provided in a format directly usable by the thermal analyzer programs. One of the primary features of TRASYS is that it allows the user to write his own executive or driver program which organizes and directs the program library routines toward solution of each specific problem in the most expeditious manner. The user also may write his own output routines, thus the system data output can directly interface with any thermal analyzer using the R-C network concept
Critical exponents of the pair contact process with diffusion
We study the pair contact process with diffusion (PCPD) using Monte Carlo
simulations, and concentrate on the decay of the particle density with
time, near its critical point, which is assumed to follow . This model is known for its slow
convergence to the asymptotic critical behavior; we therefore pay particular
attention to finite-time corrections. We find that at the critical point, the
ratio of and the pair density converges to a constant,
indicating that both densities decay with the same powerlaw. We show that under
the assumption , two of the critical exponents of
the PCPD model are and , consistent with
those of the directed percolation (DP) model
A solvable non-conservative model of Self-Organized Criticality
We present the first solvable non-conservative sandpile-like critical model
of Self-Organized Criticality (SOC), and thereby substantiate the suggestion by
Vespignani and Zapperi [A. Vespignani and S. Zapperi, Phys. Rev. E 57, 6345
(1998)] that a lack of conservation in the microscopic dynamics of an SOC-model
can be compensated by introducing an external drive and thereby re-establishing
criticality. The model shown is critical for all values of the conservation
parameter. The analytical derivation follows the lines of Broeker and
Grassberger [H.-M. Broeker and P. Grassberger, Phys. Rev. E 56, 3944 (1997)]
and is supported by numerical simulation. In the limit of vanishing
conservation the Random Neighbor Forest Fire Model (R-FFM) is recovered.Comment: 4 pages in RevTeX format (2 Figures) submitted to PR
Nonuniversal Critical Spreading in Two Dimensions
Continuous phase transitions are studied in a two dimensional nonequilibrium
model with an infinite number of absorbing configurations. Spreading from a
localized source is characterized by nonuniversal critical exponents, which
vary continuously with the density phi in the surrounding region. The exponent
delta changes by more than an order of magnitude, and eta changes sign. The
location of the critical point also depends on phi, which has important
implications for scaling. As expected on the basis of universality, the static
critical behavior belongs to the directed percolation class.Comment: 21 pages, REVTeX, figures available upon reques
Comment on `Series expansions from the corner transfer matrix renormalization group method: the hard-squares model'
Earlier this year Chan extended the low-density series for the hard-squares
partition function to 92 terms. Here we analyse this extended
series focusing on the behaviour at the dominant singularity which lies
on on the negative fugacity axis. We find that the series has a confluent
singularity of order 2 at with exponents and
. We thus confirm that the exponent has the exact
value as observed by Dhar.Comment: 5 pages, 1 figure, IoP macros. Expanded second and final versio
Thermal Radiation Analysis System (TRASYS)
A user's manual is presented for TRASYS, which is a digital software system with a generalized capability for solving radiation problems. Subroutines, file, and variable definitions are presented along with subroutine and function descriptions for the preprocessor. Definitions and descriptions of components of the processor are also presented
Synthesis of imide/arylene ether copolymers for adhesives and composite matrices
A series of imide/arylene ether copolymers were prepared from the reaction of an amorphous arylene ether oligomer and a semi-crystalline imide oligomer. These copolymers were thermally characterized and mechanical properties were measured. One block copolymer was endcapped and the molecular weight was controlled to provide a material that displayed good compression moldability and attractive adhesion and composite properties
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