Single-particle cryo-electron microscopy (cryo-EM) has recently joined X-ray crystallography and NMR spectroscopy as a high-resolution structural method for biological macromolecules. Cryo-EM was selected by Nature Me...
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The Ising model is stimulated on the manifolds of 2-dimensional quantum gravity, which are represented by fixed random triangulations (so-called quenched Ising model). Unlike the case of the Ising model on a dynamical...
The Ising model is stimulated on the manifolds of 2-dimensional quantum gravity, which are represented by fixed random triangulations (so-called quenched Ising model). Unlike the case of the Ising model on a dynamical random triangulation, there is no analytical prediction for the quenched case, since these manifolds do not have internal Hausdorff dimension and the problem cannot be formulated in matrix model language. The recursive sampling technique is used to generate the triangulations, lattice sizes being up to ten thousand triangles. The Metropolis algorithm was used for the spin update in order to obtain the initial estimation of the Curie point. After that we used the Wolff cluster algorithm in the critical region. We observed a second order phase transition, similar to that for the Ising model on a regular 2-dimensional lattice, and measured the critical exponents.
Using first-principles calculations, we predict a new type of two-dimensional(2D) boride MB3(M = Be,Ca, Sr), constituted by boron kagome monolayer and the metal atoms adsorbed above the center of the boron hexagons. T...
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Using first-principles calculations, we predict a new type of two-dimensional(2D) boride MB3(M = Be,Ca, Sr), constituted by boron kagome monolayer and the metal atoms adsorbed above the center of the boron hexagons. The band structures show that the three MB3compounds are metallic, thus the possible phononmediated superconductivity is explored. Based on the Eliashberg equation, for BeB3, CaB3, and SrB3, the calculated electron–phonon coupling constants λ are 0.46, 1.09, and 1.33, and the corresponding superconducting transition temperatures Tc are 3.2, 22.4, and 20.9 K, respectively. To explore superconductivity with higher transition temperature, hydrogenation and charge doping are further considered. The hydrogenated CaB3, i.e.,HCaB3, is stable, with the enhanced λ of 1.39 and a higher Tc of 39.3 K. Moreover, with further hole doping at the concentration of 5.8 × 1011hole/cm2, the Tc of HCaB3can be further increased to 44.2 K, exceeding the Mc Millan limit. The predicted MB3and HCaB3provide new platforms for investigating 2D superconductivity in boron kagome lattice since superconductivity based on monolayer boron kagome lattice has not been studied before.
The effects of transverse temperature distribution on the Weibel instability in a laser produced plasma are studied analytically by using a three dimensional waterbag model. It is found that the purely transverse Weib...
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The effects of transverse temperature distribution on the Weibel instability in a laser produced plasma are studied analytically by using a three dimensional waterbag model. It is found that the purely transverse Weibel instability can be stabilized for the case in which the electron beam has a more symmetric transverse temperature distribution. This analytical expectation is supported by our two dimensional particle-in-cell simulations.
Random Stealing (RS) is a well-known dynamic load-balancing algorithm, used both in shared-memory and distributed-memory systems. However, for a large-scale cluster, the simple RS policy is no longer efficient because...
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We present some explicit self-similar blow-up solutions and some other solutions of the incompressible threedimensional Navier Stokes equations. These solutions indicate that in C^∞ the solution of Navier-Stokes equa...
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We present some explicit self-similar blow-up solutions and some other solutions of the incompressible threedimensional Navier Stokes equations. These solutions indicate that in C^∞ the solution of Navier-Stokes equations does not always tend to a solution of Euler equations.
Multiple steady solutions and hysteresis phenomenon in the square cavity flows driven by the surface with antisymmetric velocity profile are investigated by numerical simulation and bifurcation analysis.A high order s...
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Multiple steady solutions and hysteresis phenomenon in the square cavity flows driven by the surface with antisymmetric velocity profile are investigated by numerical simulation and bifurcation analysis.A high order spectral element method with the matrix-free pseudo-arclength technique is used for the steady-state solution and numerical *** complex flow patterns beyond the symmetry-breaking at Re≈320 are presented by a bifurcation diagram for Re<*** results of stable symmetric and asymmetric solutions are consistent with those reported in literature,and a new unstable asymmetric branch is obtained besides the stable branches.A novel hysteresis phenomenon is observed in the range of 2208
There have been great efforts on the development of higher-order numerical schemes for compressible Euler equations in recent *** traditional test cases proposed thirty years ago mostly target on the strong shock inte...
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There have been great efforts on the development of higher-order numerical schemes for compressible Euler equations in recent *** traditional test cases proposed thirty years ago mostly target on the strong shock interactions,which may not be adequate enough for evaluating the performance of current higher-order *** order to set up a higher standard for the development of new algorithms,in this paper we present a few benchmark cases with severe and complicated wave structures and interactions,which can be used to clearly distinguish different kinds of higher-order *** tests are selected so that the numerical settings are very simple and any higher order scheme can be straightforwardly applied to these *** examples include highly oscillatory solutions and the large density ratio problem in one dimensional *** two dimensions,the cases include hurricane-like solutions;interactions of planar contact discontinuities with asymptotic large Mach number (the composite of entropy wave and vortex sheets);interaction of planar rarefaction waves with transition from continuous flows to the presence of shocks;and other types of interactions of two-dimensional planar *** get good performance on all these cases may push algorithm developer to seek for new methodology in the design of higher-order schemes,and improve the robustness and accuracy of higher-order schemes to a new level of *** order to give reference solutions,the fourth-order gas-kinetic scheme (GKS) will be used to all these benchmark cases,even though the GKS solutions may not be very accurate in some *** main purpose of this paper is to recommend other CFD researchers to try these cases as well,and promote further development of higher-order schemes.
The wake bubble expansion and contraction by adding a dense-plasma wall in the background plasma during the mode transition from laser wakefield to plasma wakefield accel- eration is investigated by particle-in-cell s...
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The wake bubble expansion and contraction by adding a dense-plasma wall in the background plasma during the mode transition from laser wakefield to plasma wakefield accel- eration is investigated by particle-in-cell simulations. The electrons are injected continuously into the cavity until the lateral bubble size equals the inner diameter of the wall. The injected electron bunch from the laser wakefield acceleration （LWFA） scheme is quasi phase-stably accel- erated forward because of the longitudinal contraction of the bubble. After the laser pulse is depleted completely, the electron bunch generated from the LWFA scheme drives a plasma wake- field. The electrons remaining in the channel are trapped and accelerated by the plasma wakefield. Ultimately, two energetic electron bunches with a narrow energy spread and low emittance are obtained.
Bubbles with different sizes have different dynamic and kinetic behavior in a two-phase bubbly flow. A common two-fluid model based on the uniform bubble size assumption is not suitable for a bubbly flow with non-unif...
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Bubbles with different sizes have different dynamic and kinetic behavior in a two-phase bubbly flow. A common two-fluid model based on the uniform bubble size assumption is not suitable for a bubbly flow with non-uniform bubble sizes. To deal with non-uniform bubbly flows, a multi-fluid model is established, with which bubbles are divided into several groups according to their sizes and a set of basic equations is derived for each group of bubbles with almost the same size. Through analyzing the bubble-bubble and bubble-pipe wall interactions, two new constitutive laws for the wall-force and pressure difference between the liquid phase and interface are developed to close the averaged basic equations. The respective phase distributions for each group of bubbles measured by a specially designed three-dimensional photographic method are used to check the model. Comparison between model-predicted values and experimental data shows that the model can describe laminar bubbly flow with non-uniform bubble sizes.
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