10,613 research outputs found
Modeling the complete Otto cycle: Preliminary version
A description is given of the equations and the computer program being developed to model the complete Otto cycle. The program incorporates such important features as: (1) heat transfer, (2) finite combustion rates, (3) complete chemical kinetics in the burned gas, (4) exhaust gas recirculation, and (5) manifold vacuum or supercharging. Changes in thermodynamic, kinetic and transport data as well as model parameters can be made without reprogramming. Preliminary calculations indicate that: (1) chemistry and heat transfer significantly affect composition and performance, (2) there seems to be a strong interaction among model parameters, and (3) a number of cycles must be calculated in order to obtain steady-state conditions
VisGenome: visualization of single and comparative genome representations
VisGenome visualizes single and comparative representations for the rat, the mouse and the human chromosomes at different levels of detail. The tool offers smooth zooming and panning which is more flexible than seen in other browsers. It presents information available in Ensembl for single chromosomes, as well as homologies (orthologue predictions including ortholog one2one, apparent ortholog one2one, ortholog many2many) for any two chromosomes from different species. The application can query supporting data from Ensembl by invoking a link in a browser
Ideal gas thermodynamic properties for the phenyl, phenoxy, and o-biphenyl radicals
Ideal gas thermodynamic properties of the phenyl and o-biphenyl radicals, their deuterated analogs and the phenoxy radical were calculated to 5000 K using estimated vibrational frequencies and structures. The ideal gas thermodynamic properties of benzene, biphenyl, their deuterated analogs and phenyl were also calculated
Computer program for calculation of complex chemical equilibrium compositions and applications. Supplement 1: Transport properties
An addition to the computer program of NASA SP-273 is given that permits transport property calculations for the gaseous phase. Approximate mixture formulas are used to obtain viscosity and frozen thermal conductivity. Reaction thermal conductivity is obtained by the same method as in NASA TN D-7056. Transport properties for 154 gaseous species were selected for use with the program
Coagulation and fragmentation processes with evolving size and shape profiles : a semigroup approach
We investigate a class of bivariate coagulation-fragmentation equations. These equations describe the evolution of a system of particles that are characterised not only by a discrete size variable but also by a shape variable which can be either discrete or continuous. Existence and uniqueness of strong solutions to the associated abstract Cauchy problems are established by using the theory of substochastic semigroups of operators
Modeling the internal combustion engine
A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics
NGC 3105: a young open cluster with low metallicity
NGC 3105 is a young open cluster hosting blue, yellow and red supergiants.
This rare combination makes it an excellent laboratory to constrain
evolutionary models of high-mass stars. It is poorly studied and fundamental
parameters such as its age or distance are not well defined. We intend to
characterize in an accurate way the cluster as well as its evolved stars, for
which we derive for the first time atmospheric parameters and chemical
abundances. We identify 126 B-type likely members within a radius of
2.70.6 arcmin, which implies an initial mass, 4100
M. We find a distance of 7.20.7 kpc for NGC 3105, placing it at
=10.01.2 kpc. Isochrone fitting supports an age of 286 Ma,
implying masses around 9.5 M for the supergiants. A high fraction of
Be stars (25 %) is found at the top of the main sequence down to
spectral type b3. From the spectral analysis we estimate for the cluster a
=+46.90.9 km s and a low metallicity,
[Fe/H]=-0.290.22. We also have determined, for the first time, chemical
abundances for Li, O, Na, Mg, Si, Ca, Ti, Ni, Rb, Y, and Ba for the evolved
stars. The chemical composition of the cluster is consistent with that of the
Galactic thin disc. An overabundance of Ba is found, supporting the enhanced
-process. NGC 3105 has a low metallicity for its Galactocentric distance,
comparable to typical LMC stars. It is a valuable spiral tracer in a very
distant region of the Carina-Sagittarius spiral arm, a poorly known part of the
Galaxy. As one of the few Galactic clusters containing blue, yellow and red
supergiants, it is massive enough to serve as a testbed for theoretical
evolutionary models close to the boundary between intermediate and high-mass
stars.Comment: 18 pages, 13 figures. Accepted for publication in A&
GEO debris and interplanetary dust: fluxes and charging behavior
In September 1996, a dust/debris detector: GORID was launched into the
geostationary (GEO) region as a piggyback instrument on the Russian Express-2
telecommunications spacecraft. The instrument began its normal operation in
April 1997 and ended its mission in July 2002. The goal of this work was to use
GORID's particle data to identify and separate the space debris to
interplanetary dust particles (IDPs) in GEO, to more finely determine the
instrument's measurement characteristics and to derive impact fluxes. While the
physical characteristics of the GORID impacts alone are insufficient for a
reliable distinction between debris and interplanetary dust, the temporal
behavior of the impacts are strong enough indicators to separate the
populations based on clustering. Non-cluster events are predominantly
interplanetary, while cluster events are debris. The GORID mean flux
distributions (at mass thresholds which are impact speed dependent) for IDPs,
corrected for dead time, are 1.35x10^{-4} m^{-2} s^{-1} using a mean detection
rate: 0.54 d^{-1}, and for space debris are 6.1x10^{-4} m^{-2} s^{-1} using a
mean detection rate: 2.5 d^{-1}. Beta-meteoroids were not detected. Clusters
could be a closely-packed debris cloud or a particle breaking up due to
electrostatic fragmentation after high charging.Comment: * Comments: 6 pages, 4 postscript figures, in Dust in Planetary
Systems 2005, Krueger, H. and Graps, A. eds., ESA Publications, SP in press
(2006). For high resolution version, see:
http://www.mpi-hd.mpg.de/dustgroup/~graps/dips2005/GrapsetalDIPS2005.pd
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