3,416 research outputs found
Gyro spring augmentation system
Spring-loaded piston with provision for hydraulic control of spring action varies the stiffness of hydraulic control systems
Microscopic Analysis of Thermodynamic Parameters from 160 MeV/n - 160 GeV/n
Microscopic calculations of central collisions between heavy nuclei are used
to study fragment production and the creation of collective flow. It is shown
that the final phase space distributions are compatible with the expectations
from a thermally equilibrated source, which in addition exhibits a collective
transverse expansion. However, the microscopic analyses of the transient states
in the reaction stages of highest density and during the expansion show that
the system does not reach global equilibrium. Even if a considerable amount of
equilibration is assumed, the connection of the measurable final state to the
macroscopic parameters, e.g. the temperature, of the transient ''equilibrium''
state remains ambiguous.Comment: 13 pages, Latex, 8 postscript figures, Proceedings of the Winter
Meeting in Nuclear Physics (1997), Bormio (Italy
Extracting the equation of state from a microscopic non-equilibrium model
We study the thermodynamic properties of infinite nuclear matter with the
Ultrarelativistic Quantum Molecular Dynamics (URQMD), a semiclassical transport
model, running in a box with periodic boundary conditions. It appears that the
energy density rises faster than at high temperatures of ~MeV. This indicates an increase in the number of degrees of freedom.
Moreover, We have calculated direct photon production in Pb+Pb collisions at
160~GeV/u within this model. The direct photon slope from the microscopic
calculation equals that from a hydrodynamical calculation without a phase
transition in the equation of state of the photon source.Comment: Proceedings of the XIV International Conference on Particles and
Nuclei (PANIC'96), 22-28 May 1996, Williamsburg, Virginia, USA, to be
published by World Scientific Publ. Co. (3 pages
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STONE 6: Artificial Sedimentary Meteorites in Space
The STONE 6 experiment demonstrated the survivability of carbonaceous and microfossiliferous martian analogue sediments during atmospheric re-entry. Doped endoliths died but their carbonised cells remained
Improved Quantification of Important Beer Quality Parameters based on Non-linear Calibration Methods applied to FT-MIR Spectra
During the production process of beer, it is of utmost importance to guarantee a high consistency of the beer quality. For instance, the bitterness is an essential quality parameter which has to be controlled within the specifications already at the beginning of the production process in the unfermented beer (wort) as well as in final products such as beer and beer mix beverages. Nowadays, analytical techniques for quality control in beer production are mainly based on manual supervision, i.e. samples are taken from the process and analyzed in the laboratory. This typically requires significant lab technicians efforts for only a small fraction of samples to be analyzed, which leads to significant costs for beer breweries and companies. Fourier transform mid-infrared (FT-MIR) spectroscopy was used in combination with non-linear multivariate calibration techniques to overcome (i) the time consuming off-line analyses in beer production and (ii) already known limitations of standard linear chemometric methods , like partial least squares (PLS), for important quality parameters [1][2] such as bitterness, citric acid, total acids, free amino nitrogen, final attenuation or foam stability. The calibration models are established with enhanced non-linear techniques based (i) on a new piece-wise linear version of PLS by employing fuzzy rules for local partitioning the latent variable space and (ii) on extensions of support vector regression variants (ε-PLSSVR and ν-PLSSVR), for overcoming high computation times in high-dimensional problems and time-intensive and inappropriate settings of the kernel parameters. Furthermore, we introduce a new model selection scheme based on bagged ensembles in order to improve robustness and thus predictive quality of the final models. The approaches are tested on real-world calibration data sets for wort and beer mix beverages, and successfully compared to linear methods, as showing a clear out-performance in most cases and being able to meet the model quality requirements defined by the experts at the beer company
Signatures of dense hadronic matter in ultrarelativistic heavy ion reactions
The behavior of hadronic matter at high baryon densities is studied within
Ultrarelativistic Quantum Molecular Dynamics (URQMD). Baryonic stopping is
observed for Au+Au collisions from SIS up to SPS energies. The excitation
function of flow shows strong sensitivities to the underlying equation of state
(EOS), allowing for systematic studies of the EOS. Dilepton spectra are
calculated with and without shifting the pole. Except for S+Au
collisions our calculations reproduce the CERES data.Comment: Invited talk at RHIC-theory workshop at BNL july 8-1
Equilibrium and nonequilibrium effects in nucleus nucleus collisions
Abstract: Local thermal and chemical equilibration is studied for central AqA collisions at 10.7 160 AGeV in the Ultrarelativis- . tic Quantum Molecular Dynamics model UrQMD . The UrQMD model exhibits strong deviations from local equilibrium at the high density hadron string phase formed during the early stage of the collision. Equilibration of the hadron resonance matter is established in the central cell of volume Vs125 fm3 at later stages, tG10 fmrc, of the resulting quasi-isentropic expansion. The thermodynamical functions in the cell and their time evolution are presented. Deviations of the UrQMD quasi-equilibrium state from the statistical mechanics equilibrium are found. They increase with energy per baryon and lead to a strong enhancement of the pion number density as compared to statistical mechanics estimates at SPS energies. PACS: 25.75.-q; 24.10.Lx; 24.10.Pa; 64.30.q
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