Numerical study on the response of shoreline change to the tidal channel after a beach nourishment project on an embayed beach

Beach erosion is a severe problem worldwide and beach nourishment is widely regarded today as an environmentally acceptable method to protect and enlarge beaches. In many beach nourishment projects on headland-bay beaches, artificial headlands were constructed on the natural headlands to form an embayed beach in static equilibrium to protect the beach more effectively. However, the construction of artificial headland would weaken the water exchange in the bay and make the water quality easy to deteriorate. In a beach nourishment project in Qinhuangdao, China to dispose this discrepancy an engineering measure was conducted: to reserve a tidal channel between the artificial headland and the natural headland to allow the tidal current to pass. In this paper, a shoreline change model was set up based on GENESIS model to evaluate the influence of the reserve of the tidal channel on the shoreline change after the project. The model was verified by reproducing the post-project shoreline. Four different project schemes with different scales of tidal channel were simulated and discussion was given based on the analysis of simulated results. The numerical evaluation of various scheme options indicates that it is feasible to involve the tidal channel in beach nourishment projects with artificial headland and the scale of the tidal channel should be designed based on the hydrodynamic processes and the state of the beach

Spin-dependent structure functions g^1\hat g_1 and g^2\hat g_2 for inclusive spin-half baryon production in electron-positron annihilation

Two spin-dependent structure functions $\hat g_1$ and $\hat g_2$ for the inclusive spin-half baryon production in electron-positron annihilation are studied in the context of QCD factorization as well as in the naive quark parton model. As a result, it is found that the sum of $\hat g_1$ and $\hat g_2$ is related to $\hat h_1$ and $\hat g_T$, two quark fragmentation functions defined by Jaffe and Ji. In connection with the measurement of quark fragmentation functions, the possible phenomenological consequences are discussed.Comment: RevTex, four Ps figures, to appear in Phys. Rev.

The Transformation from Translucent into Transparent Rare Earth Ions Doped Oxyfluoride Glass-Ceramics with Enhanced Luminescence

Article reporting a scenario where a translucent Er3+−Yb3+ doped oxyfluoride precursor glass-ceramic (P-GC) becomes transparent with increasing crystal size and crystallinity

The Flare-energy Distributions Generated by Kink-unstable Ensembles of Zero-net-current Coronal Loops

It has been proposed that the million degree temperature of the corona is due to the combined effect of barely-detectable energy releases, so called nanoflares, that occur throughout the solar atmosphere. Alas, the nanoflare density and brightness implied by this hypothesis means that conclusive verification is beyond present observational abilities. Nevertheless, we investigate the plausibility of the nanoflare hypothesis by constructing a magnetohydrodynamic (MHD) model that can derive the energy of a nanoflare from the nature of an ideal kink instability. The set of energy-releasing instabilities is captured by an instability threshold for linear kink modes. Each point on the threshold is associated with a unique energy release and so we can predict a distribution of nanoflare energies. When the linear instability threshold is crossed, the instability enters a nonlinear phase as it is driven by current sheet reconnection. As the ensuing flare erupts and declines, the field transitions to a lower energy state, which is modelled by relaxation theory, i.e., helicity is conserved and the ratio of current to field becomes invariant within the loop. We apply the model so that all the loops within an ensemble achieve instability followed by energy-releasing relaxation. The result is a nanoflare energy distribution. Furthermore, we produce different distributions by varying the loop aspect ratio, the nature of the path to instability taken by each loop and also the level of radial expansion that may accompany loop relaxation. The heating rate obtained is just sufficient for coronal heating. In addition, we also show that kink instability cannot be associated with a critical magnetic twist value for every point along the instability threshold

Nuclear Shadowing in DIS: Numerical Solution of the Evolution Equation for the Green Function

Within a light-cone QCD formalism based on the Green function technique incorporating color transparency and coherence length effects we study nuclear shadowing in deep-inelastic scattering at moderately small Bjorken x_{Bj}. Calculations performed so far were based only on approximations leading to an analytical harmonic oscillatory form of the Green function. We present for the first time an exact numerical solution of the evolution equation for the Green function using realistic form of the dipole cross section and nuclear density function. We compare numerical results for nuclear shadowing with previous predictions and discuss differences.Comment: 21 pages including 3 figures; a small revision of the tex

Scattering of elastic waves by periodic arrays of spherical bodies

We develop a formalism for the calculation of the frequency band structure of a phononic crystal consisting of non-overlapping elastic spheres, characterized by Lam\'e coefficients which may be complex and frequency dependent, arranged periodically in a host medium with different mass density and Lam\'e coefficients. We view the crystal as a sequence of planes of spheres, parallel to and having the two dimensional periodicity of a given crystallographic plane, and obtain the complex band structure of the infinite crystal associated with this plane. The method allows one to calculate, also, the transmission, reflection, and absorption coefficients for an elastic wave (longitudinal or transverse) incident, at any angle, on a slab of the crystal of finite thickness. We demonstrate the efficiency of the method by applying it to a specific example.Comment: 19 pages, 5 figures, Phys. Rev. B (in press

Determinantal point processes associated with Hilbert spaces of holomorphic functions

International audienceWe study determinantal point processes on C induced by the reproducing kernels of generalized Fock spaces as well as those on the unit disc D induced by the reproducing kernels of generalized Bergman spaces. In the first case, we show that all reduced Palm measures of the same order are equivalent. The Radon-Nikodym derivatives are computed explicitly using regularized multiplicative functionals. We also show that these determinantal point processes are rigid in the sense of Ghosh and Peres, hence reduced Palm measures of different orders are singular. In the second case, we show that all reduced Palm measures, of all orders, are equivalent. The Radon-Nikodym derivatives are computed using regularized multiplicative function-als associated with certain Blaschke products. The quasi-invariance of these deter-minantal point processes under the group of diffeomorphisms with compact supports follows as a corollary

Measurements of the observed cross sections for e+e−→e^+e^-\to exclusive light hadrons containing π0π0\pi^0\pi^0 at s=3.773\sqrt s= 3.773, 3.650 and 3.6648 GeV

By analyzing the data sets of 17.3, 6.5 and 1.0 pb$^{-1}$ taken, respectively, at $\sqrt s= 3.773$, 3.650 and 3.6648 GeV with the BES-II detector at the BEPC collider, we measure the observed cross sections for $e^+e^-\to \pi^+\pi^-\pi^0\pi^0$, $K^+K^-\pi^0\pi^0$, $2(\pi^+\pi^-\pi^0)$, $K^+K^-\pi^+\pi^-\pi^0\pi^0$ and $3(\pi^+\pi^-)\pi^0\pi^0$ at the three energy points. Based on these cross sections we set the upper limits on the observed cross sections and the branching fractions for $\psi(3770)$ decay into these final states at 90% C.L..Comment: 7 pages, 2 figure