15,986 research outputs found
Global Hilbert Expansion for the Vlasov-Poisson-Boltzmann System
We study the Hilbert expansion for small Knudsen number for the
Vlasov-Boltzmann-Poisson system for an electron gas. The zeroth order term
takes the form of local Maxwellian: $ F_{0}(t,x,v)=\frac{\rho_{0}(t,x)}{(2\pi
\theta_{0}(t,x))^{3/2}} e^{-|v-u_{0}(t,x)|^{2}/2\theta_{0}(t,x)},\text{\
}\theta_{0}(t,x)=K\rho_{0}^{2/3}(t,x).t=0u_00\leq t\leq \varepsilon
^{-{1/2}\frac{2k-3}{2k-2}},\rho_{0}(t,x) u_{0}(t,x)\gamma=5/3$
Simulation of aromatic SOA formation using the lumping model integrated with explicit gas-phase kinetic mechanisms and aerosol-phase reactions
The Unified Partitioning-Aerosol phase Reaction (UNIPAR) model has been
developed to predict the secondary organic aerosol (SOA) formation through
multiphase reactions. The model was evaluated with aromatic SOA data produced
from the photooxidation of toluene and 1,3,5-trimethylbenzene (135-TMB) under
various concentrations of NO<sub>x</sub> and SO<sub>2</sub> using an outdoor
reactor (University of Florida Atmospheric PHotochemical Outdoor Reactor
(UF-APHOR) chamber). When inorganic species (sulfate, ammonium and water)
are present in aerosol, the prediction of both toluene SOA and 135-TMB SOA,
in which the oxygen-to-carbon (O : C) ratio is lower than 0.62, are approached
under the assumption of a complete organic/electrolyte-phase separation below
a certain relative humidity. An explicit gas-kinetic model was employed to
express gas-phase oxidation of aromatic hydrocarbons. Gas-phase products are
grouped based on their volatility (6 levels) and reactivity (5 levels) and
exploited to construct the stoichiometric coefficient (α<sub>i,j</sub>)
matrix, the set of parameters used to describe the concentrations of organic
compounds in multiphase. Weighting of the α<sub>i,j</sub> matrix as a function
of NO<sub>x</sub> improved the evaluation of NO<sub>x</sub> effects on aromatic
SOA. The total amount of organic matter (OM<sub>T</sub>) is predicted by two modules
in the UNIPAR model: OM<sub>P</sub> by a partitioning process and OM<sub>AR</sub> by
aerosol-phase reactions. The OM<sub>AR</sub> module predicts multiphase reactions of
organic compounds, such as oligomerization, acid-catalyzed reactions, and
organosulfate (OS) formation. The model reasonably simulates SOA formation
under various aerosol acidities, NO<sub>x</sub> concentrations, humidities and
temperatures. Furthermore, the OS fractions in the SOA predicted by the model
were in good agreement with the experimentally measured OS fractions
Isometric Representations of Totally Ordered Semigroups
Let S be a subsemigroup of an abelian torsion-free group G. If S is a
positive cone of G, then all C*-algebras generated by faithful isometrical
non-unitary representations of S are canonically isomorphic. Proved by Murphy,
this statement generalized the well-known theorems of Coburn and Douglas. In
this note we prove the reverse. If all C*-algebras generated by faithful
isometrical non-unitary representations of S are canonically isomorphic, then S
is a positive cone of G. Also we consider G = Z\times Z and prove that if S
induces total order on G, then there exist at least two unitarily not
equivalent irreducible isometrical representation of S. And if the order is
lexicographical-product order, then all such representations are unitarily
equivalent.Comment: February 21, 2012. Kazan, Russi
Mechanical Properties Transformation on Zr54Al17Co29 Bulk Metallic Glass by Partial Crystallization
Study on biomaterials is recently essential for rapid development of medical application and Zr54Al17Co29 BMGbecomes promising candidate due to the lack of toxic elements. Partial crystallization by isothermal annealing at SCL region was used to variate the crystallinities of BMG. The structural and thermal properties of as cast and partially crystallized samples were confirmed by XRD and DSC test, while microvickers and compression test were further utilized to investigate their mechanical properties. By the higher crystallinity, the hardness could be slightly increased in range 540 ± 5 to 575 ± 5 Hv. As-cast sample shows the yield strength and plastic strain of 2130 ± 75 MPa and 2.2 ± 1.6%. The yield strength is increased by the presence of 10% nanocrystal, afterwards, fall and raise phenomena are obtained with further crystallinity. However, with higher crystallinity, the plasticity is significantly degraded and no more plastic strain observed at sample with 50% of crystallinity. Both the presence of nanocrystalline phase and free volume annihilation are the reason of mechanical properties change on the Zr-based BMG
Production and optical properties of liquid scintillator for the JSNS experiment
The JSNS (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron
Source) experiment will search for neutrino oscillations over a 24 m short
baseline at J-PARC. The JSNS inner detector will be filled with 17 tons
of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of
unloaded LS in the intermediate -catcher and outer veto volumes.
JSNS has chosen Linear Alkyl Benzene (LAB) as an organic solvent because
of its chemical properties. The unloaded LS was produced at a refurbished
facility, originally used for scintillator production by the RENO experiment.
JSNS plans to use ISO tanks for the storage and transportation of the LS.
In this paper, we describe the LS production, and present measurements of its
optical properties and long term stability. Our measurements show that storing
the LS in ISO tanks does not result in degradation of its optical properties.Comment: 7 pages, 4 figures
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