7,159 research outputs found
Stability optimization of laminated composite plates
The optimum design of plates with orthotropic layers under axial compression and shear is discussed. The plates considered are the laminates of N orthotropic layers whose principal material axes coincide with the plate axes. Each layer is assumed to have the same thickness and an equal number of fibers in the direction of + alpha sub i and - alpha sub i with respect to the plate axis. The fiber directions which give the highest axial buckling stress and the highest shear buckling stress are found by utilizing a mathematical optimization technique for various aspect ratios of the plates. Inhomogeneity in the direction of the plate thickness (stacking sequence) is taken into account in this analysis
Observational tests for oscillating expansion rate of the Universe
We investigate the observational constraints on the oscillating scalar field
model using data from type Ia supernovae, cosmic microwave background
anisotropies, and baryon acoustic oscillations. According to a Fourier
analysis, the galaxy number count from redshift data indicates that
galaxies have preferred periodic redshift spacings. We fix the mass of the
scalar field as such that the scalar
field model can account for the redshift spacings, and we constrain the other
basic parameters by comparing the model with accurate observational data. We
obtain the following constraints: (95% C.L.),
(95% C.L.) (in the range
). The best fit values of the energy density parameter of the scalar
field and the coupling constant are and ,
respectively. The value of is close to but not equal to .
Hence, in the scalar field model, the amplitude of the galaxy number count
cannot be large. However, because the best fit values of and
are not , the scalar field model has the possibility of accounting for
the periodic structure in the -- relation of galaxies. The variation of
the effective gravitational constant in the scalar field model is not
inconsistent with the bound from observation.Comment: 9 pages, 11 figures, 1 table, Accepted for publication in Physical
Review
On injective hulls of simple modules
We characterize a ring over which every left module of finite length has an injective hull of finite length. Using this, we show that finite normalizing extensions of such a ring also have the same property. We also consider rings having the property that the injective hull of every simple module is artinian. We show that certain noncommutative noetherian rings have this property
Can transport peak explain the low-mass enhancement of dileptons at RHIC?
We propose a novel relation between the low-mass enhancement of dielectrons
observed at PHENIX and transport coefficients of QGP such as the charge
diffusion constant and the relaxation time . We parameterize
the transport peak in the spectral function using the second-order relativistic
dissipative hydrodynamics by Israel and Stewart. Combining the spectral
function and the full (3+1)-dimensional hydrodynamical evolution with the
lattice EoS, theoretical dielectron spectra and the experimental data are
compared. Detailed analysis suggests that the low-mass dilepton enhancement
originates mainly from the high-temperature QGP phase where there is a large
electric charge fluctuation as obtained from lattice QCD simulations.Comment: To appear in the conference proceedings for Quark Matter 2011, May 23
- May 28, Annecy, Franc
Potential Profiling of the Nanometer-Scale Charge Depletion Layer in n-ZnO/p-NiO Junction Using Photoemission Spectroscopy
We have performed a depth-profile analysis of an all-oxide p-n junction diode
n-ZnO/p-NiO using photoemission spectroscopy combined with Ar-ion sputtering.
Systematic core-level shifts were observed during the gradual removal of the
ZnO overlayer, and were interpreted using a simple model based on charge
conservation. Spatial profile of the potential around the interface was
deduced, including the charge-depletion width of 2.3 nm extending on the ZnO
side and the built-in potential of 0.54 eV
Jet-fluid string formation and decay in high-energy heavy-ion collisions
We propose a new hadronization mechanism, jet-fluid string (JFS) formation
and decay, to understand observables in intermediate to high- regions
comprehensively. In the JFS model, hard partons produced in jet lose their
energy in traversing the QGP fluid, which is described by fully
three-dimensional hydrodynamic simulations. When a jet parton escapes from the
QGP fluid, it picks up a partner parton from a fluid and forms a color singlet
string, then it decays to hadrons. We find that high- values in JFS
are about two times larger than in the independent fragmentation model.Comment: 6 pages, 2 figures; Proceeding for poster sessions at Quark Matter
2006, Shanghai, China, 14-20 November 2006; to appear in Int. J. of Mod.
Phys.
Derived factorization categories of non-Thom–Sebastiani-type sums of potentials
We first prove semi-orthogonal decompositions of derived factorizationcategories arising from sums of potentials of gauged Landau-Ginzburg models,where the sums are not necessarily Thom--Sebastiani type. We then apply theresult to the category of maximally graded matrixfactorizations of an invertible polynomial of chain type, and explicitlyconstruct a full strong exceptional collection ,..., in {\rmHMF}^{L_f}(f) whose length is the Milnor number of theBerglund--H\"ubsch transpose of . This proves a conjecture,which postulates that for an invertible polynomial the category {\rmHMF}^{L_f}(f) admits a tilting object, in the case when is a chainpolynomial. Moreover, by careful analysis of morphisms between the exceptionalobjects , we explicitly determine the quiver with relations whichrepresents the endomorphism ring of the associated tilting object in , and in particular we obtain anequivalence .<br
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