9,349 research outputs found
Effects of Marangoni numbers on thermocapillary drop migration: constant for quasi-steady state?
The overall {\it steady}-state energy balance with two phases in a flow
domain requires that the change in energy of the domain is equal to the
difference between the total energy entering the domain and that leaving the
domain. From the condition, the integral thermal flux across the surface is
studied for a {\it steady} thermocapillary drop migration in a flow field with
uniform temperature gradient at small and large Marangoni (Reynolds) numbers.
The drop is assumed to have only a slight axisymmetric deformation from a
sphere. It is identified that a conservative/nonconservative integral thermal
flux across the surface in the {\it steady} thermocapillary drop migration at
small/large Marangoni (Reynolds) numbers. The conservative flux confirms the
assumption of {\it quasi-steady} state in the thermocapillary drop migration at
small Marangoni (Reynolds) numbers. The nonconservative flux may well result
from the invalid assumption of {\it quasi-steady} state, which indicates that
the thermocapillary drop migration at large Marangoni (Reynolds) numbers cannot
reach {\it steady} state and is thus a {\it unsteady} process.Comment: 21 pages. arXiv admin note: text overlap with arXiv:1112.276
Su(3) Algebraic Structure of the Cuprate Superconductors Model based on the Analogy with Atomic Nuclei
A cuprate superconductor model based on the analogy with atomic nuclei was
shown by Iachello to have an structure. The mean-field approximation
Hamiltonian can be written as a linear function of the generators of
algebra. Using algebraic method, we derive the eigenvalues of the reduced
Hamiltonian beyond the subalgebras and of
algebra. In particular, by considering the coherence between s- and d-wave
pairs as perturbation, the effects of coherent term upon the energy spectrum
are investigated
Anti-Lambda polarization in high energy pp collisions with polarized beam
We study the polarization of the anti-Lambda particle in polarized high
energy pp collisions at large transverse momenta. The anti-Lambda polarization
is found to be sensitive to the polarization of the anti-strange sea of the
nucleon. We make predictions using different parameterizations of the polarized
quark distribution functions. The results show that the measurement of
longitudinal anti-Lambda polarization can distinguish different
parameterizations, and that similar measurements in the transversely polarized
case can give some insights into the transversity distribution of the
anti-strange sea of nucleon.Comment: 11 pages, 4 figure
Hyperon polarization in e^-p --> e^-HK with polarized electron beams
We apply the picture proposed in a recent Letter for transverse hyperon
polarization in unpolarized hadron-hadron collisions to the exclusive process
e^-p --> e^-HK such as e^-p-->e^-\Lambda K^+, e^-p --> e^-\Sigma^+ K^0, or
e^-p--> e^-\Sigma^0 K^+, or the similar process e^-p\to e^-n\pi^+ with
longitudinally polarized electron beams. We present the predictions for the
longitudinal polarizations of the hyperons or neutron in these reactions, which
can be used as further tests of the picture.Comment: 15 pages, 2 figures. submitted to Phys. Rev.
Spin transfer and polarization of antihyperons in lepton induced reactions
We study the polarization of antihyperon in lepton induced reactions such as
and with polarized beams using
different models for spin transfer in high energy fragmentation processes. We
compare the results with the available data and those for hyperons. We make
predictions for future experiments.Comment: 31 pages, 6 figures. submitted to Phys. Rev. D. content changed,
references adde
Correlation effects in the ground state charge density of Mott-insulating NiO: a comparison of ab-initio calculations and high-energy electron diffraction measurements
Accurate high-energy electron diffraction measurements of structure factors
of NiO have been carried out to investigate how strong correlations in the Ni
3d shell affect electron charge density in the interior area of nickel ions and
whether the new ab-initio approaches to the electronic structure of strongly
correlated metal oxides are in accord with experimental observations. The
generalized gradient approximation (GGA) and the local spin density
approximation corrected by the Hubbard U term (LSDA+U) are found to provide the
closest match to experimental measurements. The comparison of calculated and
observed electron charge densities shows that correlations in the Ni 3d shell
suppress covalent bonding between the oxygen and nickel sublattices.Comment: 6 pages, LaTeX and 5 figures in the postscript forma
Magnetically asymmetric interfaces in a (LaMnO)/(SrMnO) superlattice due to structural asymmetries
Polarized neutron reflectivity measurements of a ferromagnetic
[(LaMnO)/(SrMnO)] superlattice reveal a modulated
magnetic structure with an enhanced magnetization at the interfaces where
LaMnO was deposited on SrMnO (LMO/SMO). However, the opposite
interfaces (SMO/LMO) are found to have a reduced ferromagnetic moment. The
magnetic asymmetry arises from the difference in lateral structural roughness
of the two interfaces observed via electron microscopy, with strong
ferromagnetism present at the interfaces that are atomically smooth over tens
of nanometers. This result demonstrates that atomic-scale roughness can
destabilize interfacial phases in complex oxide heterostructures.Comment: 5 pages, 4 figure
Temperature dependence of single-particle properties in nuclear matter
The single-nucleon potential in hot nuclear matter is investigated in the
framework of the Brueckner theory by adopting the realistic Argonne V18 or
Nijmegen 93 two-body nucleon-nucleon interaction supplemented by a microscopic
three-body force. The rearrangement contribution to the single-particle
potential induced by the ground state correlations is calculated in terms of
the hole-line expansion of the mass operator and provides a significant
repulsive contribution in the low-momentum region around and below the Fermi
surface. Increasing temperature leads to a reduction of the effect, while
increasing density makes it become stronger. The three-body force suppresses
somewhat the ground state correlations due to its strong short-range repulsion,
increasing with density. Inclusion of the three-body force contribution results
in a quite different temperature dependence of the single-particle potential at
high enough densities as compared to that adopting the pure two-body force. The
effects of three-body force and ground state correlations on the nucleon
effective mass are also discussed.Comment: 14 pages, 5 figure
Pore Pressure in Silty Sand under Cyclic Shear
In order to study the liquefaction phenomena of silty sand, saturated specimens prepared in the laboratory according to the dry unit weight of undisturbed samples are used to examine the cyclic shear resistance, pore pressure and residual shear strain developed in these specimens under cyclic loading. These tests are accomplished with a cyclic simple shear test apparatus developed in Nanjing Hydraulic Research Institute. Based on results of these tests expressions of cyclic shear resistance, pore pressure, dynamic shear modulus and residual shear strain as functions of number of cycles, consolidation pressure, initial and cyclic shear stress etc. have been developed
Multi-Fidelity Modeling and Simulation of Wave Energy Converters
Equations governing the response of wave energy converters (WECs) consist of partial differential equations and nonlinear boundary conditions that model the wave absorption, which is commonly used for classification of WECs, wave radiation and diffraction as required for prediction of wave energy generation by WEC farms, the converter’s response and the transduction mechanism.
To date, the modeling and simulation of WECs or WEC arrays are based on linear wave theory, which assumes irrotational flow and limits the analysis for design to small wave amplitudes. In contrast, it is desirable to operate WECs in large waves under resonance conditions that would lead to large amplitude motions for effective energy conversion. With large amplitude waves and motions or responses, the linear and irrotational flow assumptions would not be valid. In this talk, we present a review and examples of (1) physics-based multi-fidelity modeling and simulation procedures that could be performed to develop effective control and optimization strategies for different types of WECs, and (2) nonlinear phenomena that can be exploited to enhance the performance of WECs
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