17,913 research outputs found
The impact of a wave farm on large scale sediment transport
This study investigates the interactions of waves and tides at a wave farm in the southwest of England, in particular their effects on radiation stress, bottom stress, and consequently on the sediment transport and the coast adjacent to the wave-farm (the Wave Hub). In this study, an integrated complex numerical modelling system is setup at the Wave Hub site and is used to compute the wave and current fields by taking into account the wave-current interaction, as well as the sediment transport. Results show that tidal elevation and tidal currents have a significant effect on the wave height and direction predictions; tidal forcing and wind waves have a significant effect on the bed shear-stress, relevant to sediment transport; waves via radiation stresses have an important effect on the longshore and cross-shore velocity components, particularly during the spring tides. Waves can impact on bottom boundary layer and mixing in the water column. The results highlight the importance of the interactions between waves and tides when modelling coastal morphology with presence of wave energy devices
Analytic study of Gauss-Bonnet holographic superconductors in Born-Infeld electrodynamics
Using Sturm-Liouville (SL) eigenvalue problem, we investigate several
properties of holographic s-wave superconductors in Gauss-Bonnet gravity with
Born-Infeld electrodynamics in the probe limit. Our analytic scheme has been
found to be in good agreement with the numerical results. From our analysis it
is quite evident that the scalar hair formation at low temperatures is indeed
affected by both the Gauss-Bonnet as well as the Born-Infeld coupling
parameters. We also compute the critical exponent associated with the
condensation near the critical temperature. The value of the critical exponent
thus obtained indeed suggests a universal mean field behavior.Comment: 9 pages, Latex, minor modifications, To appear in JHE
A Note on Gauss-Bonnet Holographic Superconductors
We present an analytic treatment near the phase transition for the critical
temperature of (3+1)-dimensional holographic superconductors in
Einstein-Gauss-Bonnet gravity with backreaction. We find that the backreaction
makes the critical temperature of the superconductor decrease and condensation
harder. This is consistent with previous numerical results.Comment: 6 pages, typos corrected, references added, published versio
Ferromagnetism in 2p Light Element-Doped II-oxide and III-nitride Semiconductors
II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light
elements are investigated as potential dilute magnetic semiconductors (DMS).
Based on our first-principle calculations, nitrogen doped ZnO, carbon doped
ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism
of such DMS materials can be attributed to a p-d exchange-like p-p coupling
interaction which is derived from the similar symmetry and wave function
between the impurity (p-like t_2) and valence (p) states. We also propose a
co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to enhance
the ferromagnetic coupling and to increase the solubility and activity
Upconversion of optical signals with multi-longitudinal-mode pump lasers
Multi-longitudinal-mode lasers have been believed to be good candidates as
pump sources for optical frequency conversion. However, we present a
semi-classical model for frequency conversion of optical signals with a
multimode pump laser, which shows that fluctuations of the instantaneous pump
power limit the conversion efficiency. In an experiment, we upconverted a 1550
nm optical signal in a periodically poled lithium niobate waveguide using with
a multi-longitudinal-mode laser, an observed a maximum conversion efficiency of
70%, in good agreement with our theoretical model. Compared to single-mode
pumping, multimode pumping is not a suitable technique for attaining stable
near-unity-efficiency frequency conversion. However, the results obtained here
could find application in characterization of the spectral or temporal
structure of multi-longitudinal-mode lasers.Comment: 6 pages, 4 figures, comments are welcome
Soft Clay Ground Improvement of Ningbo International Airport
Ningbo International Airport is built on the soft clay ground first in China. It has a runway 3,000m in length and 45m in width. The thickness of soft clay is greater than 32m. The calculating consolidation settlement is 0. 48m, far beyond to allowable limit. The soft clay ground is improved by wick drain and surcharge precompression. The airport has been put in service since July, 1990. The process and the results of a full scale embankment test, the ground improvement and the settlement observation are described. The influence of the smear and the well resistance of the wick drain on the consolidation rate are discussed
Differential Expression ESTs Associated with Fluorosis in Rats Liver
The fluoride has volcanic activity and abundantly exists in environment combining with other elements as fluoride compounds. Recent researches indicated that the molecular mechanisms of intracellular fluoride toxicity were very complex. However, the molecular mechanisms underlying the effects on gene expression of chronic fluoride-induced damage is unknown, especially the detailed regulatory process of mitochondria. In the present study, we screened the differential expression ESTs associated with fluorosis by DDRT-PCR in rat liver. We gained 8 genes, 3 new ESTs, and 1 unknown function sequence and firstly demonstrated that microsomal glutathione S-transferase 1 (MGST1), ATP synthase H+ transporting mitochondrial F0 complex subunit C1, selenoprotein S, mitochondrial IF1 protein, and mitochondrial succinyl-CoA synthetase alpha subunit were participated in mitochondria metabolism, functional and structural damage process caused by chronic fluorosis. This information will be very helpful for understanding the molecular mechanisms of fluorosis
The induced representations of Brauer algebra and the Clebsch-Gordan coefficients of SO(n)
Induced representations of Brauer algebra from with are discussed. The induction coefficients
(IDCs) or the outer-product reduction coefficients (ORCs) of with up to a normalization factor are
derived by using the linear equation method. Weyl tableaus for the
corresponding Gel'fand basis of SO(n) are defined. The assimilation method for
obtaining CG coefficients of SO(n) in the Gel'fand basis for no modification
rule involved couplings from IDCs of Brauer algebra are proposed. Some
isoscalar factors of for the resulting irrep
with
$\sum\limits_{i=1}^{4}\lambda_{i}\leq .Comment: 48 pages latex, submitted to Journal of Phys.
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