基于LS-DYNA的高速破片水中运动特性流固耦合数值模拟

基于大型有限元分析软件ANSYS/LS-DYNA,建立三维长方体高速破片在水介质中运动的有限元动力分析模型,采用ALE方法对破片在水下运动过程进行流固耦合数值模拟,获得了破片的速度衰减曲线。研究了速度衰减规律、破片墩粗变形规律以及冲击波传播过程。得到高速破片的侵彻能力随速度的变化规律:当初速度大于910~1 115m/s时破片头部将产生显著变形,并大大影响其侵彻阻力;当破片速度较小时,水中侵彻距离随破片初速的增大而增大,当破片速度达到某临界值以后,侵彻距离将随初始速度的增大而逐渐减小。     

Zur Materialabhängigkeit des Massenschwächwächungskoeffizienten von β-Strahlung

Catalase was desactivated in aqueous solution by irradiation with gamma-rays or ultrasound with nearly equal yields, if the applied doses were related to the response of a chemical dosimeter. The decrease of the enzymatic activity proceeded in parallel to the release of ¹²³iodine from ¹²⁵I-(iodo)-catalase. The same competition kinetics were observed in the radiolytic and sonolytic bleaching of p-nitrosodimethylaniline in the presence of catalase, respectively. It is concluded, that OH-radicals were, responsible for the sonolytic destruction of catalase. Phospholipids exerted a protective effect, which may be useful in the preparation of liposomes as carriers of macromolecules.     

Theoretical and numerical studies on the flow multiplicity phenomenon for gas–solids two-phase flows in CFB risers

The dependence of the fully-developed flow profiles on the inlet flow conditions for gas–solids two-phase flows, i.e. the flow multiplicity phenomenon, in circulating fluidized bed (CFB) risers was proposed and discussed in this article. The flow multiplicity phenomenon for gas–solids two-phase flows was first proved mathematically based on the conservation equations of mass and momentum. Then the CFD model using Eulerian–Eulerian approach with k–ε turbulence model for each phase was further adopted to analyze the details of this flow multiplicity phenomenon. It is theoretically and numerically revealed that for gas–solids two-phase flows, the flow profiles in the fully-developed region are always dominated by the flow profiles at the inlet. The solids concentration profile is closely coupled with the velocity profile, and the inlet solids concentration and velocity profiles can largely influence the fully-developed concentration and velocity profiles.     

Wall crossings for double Hurwitz numbers

Double Hurwitz numbers count covers of P¹ by genus g curves with assigned ramification profiles over 0 and ∞, and simple ramification over a fixed branch divisor. Goulden, Jackson and Vakil have shown double Hurwitz numbers are piecewise polynomial in the orders of ramification (Goulden et al., 2005) [10], and Shadrin, Shapiro and Vainshtein have determined the chamber structure and wall crossing formulas for g=0 (Shadrin et al., 2008) [15]. This paper gives a unified approach to these results and strengthens them in several ways — the most important being the extension of the results of Shadrin et al. (2008) [15] to arbitrary genus.The main tool is the authors? previous work (Cavalieri et al., 2010) [6] expressing double Hurwitz number as a sum over certain labeled graphs. We identify the labels of the graphs with lattice points in the chambers of certain hyperplane arrangements, which give rise to piecewise polynomial functions. Our understanding of the wall crossing for these functions builds on the work of Varchenko (1987) [17], and could have broader applications.     

The Hodge structure of the coloring complex of a hypergraph

Let G be a simple graph with n vertices. The coloring complex Δ(G) was defined by Steingrímsson, and the homology of Δ(G) was shown to be nonzero only in dimension n−3 by Jonsson. Hanlon recently showed that the Eulerian idempotents provide a decomposition of the homology group H_n−3(Δ(G)) where the dimension of the jth component in the decomposition, , equals the absolute value of the coefficient of λ^j in the chromatic polynomial of G, χ_G(λ).Let H be a hypergraph with n vertices. In this paper, we define the coloring complex of a hypergraph, Δ(H), and show that the coefficient of λ^j in χ_H(λ) gives the Euler Characteristic of the jth Hodge subcomplex of the Hodge decomposition of Δ(H). We also examine conditions on a hypergraph, H, for which its Hodge subcomplexes are Cohen–Macaulay, and thus where the absolute value of the coefficient of λ^j in χ_H(λ) equals the dimension of the jth Hodge piece of the Hodge decomposition of Δ(H). We also note that the Euler Characteristic of the jth Hodge subcomplex of the Hodge decomposition of the intersection of coloring complexes is given by the coefficient of jth term in the associated chromatic polynomial.     

Coincidence of strict s-numbers of weighted Hardy operators

We establish the equality of all the so-called strict s-numbers of the weighted Hardy operator T:Lp(I)→Lp(I), where 1<p<∞, I=(a,b)⊂R and

     

A CM construction for curves of genus 2 with p-rank 1

We construct Weil numbers corresponding to genus-2 curves with p-rank 1 over the finite field Fp² of p² elements. The corresponding curves can be constructed using explicit CM constructions. In one of our algorithms, the group of Fp²-valued points of the Jacobian has prime order, while another allows for a prescribed embedding degree with respect to a subgroup of prescribed order. The curves are defined over Fp² out of necessity: we show that curves of p-rank 1 over Fp for large p cannot be efficiently constructed using explicit CM constructions.     

Some identities on Catalan numbers and hypergeometric functions via Catalan matrix power

In this paper we use the Catalan matrix power as a tool for deriving identities involving Catalan numbers and hypergeometric functions. For that purpose, we extend earlier investigated relations between the Catalan matrix and the Pascal matrix by inserting the Catalan matrix power and particulary the squared Catalan matrix in those relations. We also pay attention to some relations between Catalan matrix powers of different degrees, which allows us to derive the simplification formula for hypergeometric function ₃F₂, as well as the simplification formula for the product of the Catalan number and the hypergeometric function ₃F₂. Some identities involving Catalan numbers, proved by the non-matrix approach, are also given.     

Integral representations for the generalized Bedient polynomials and the generalized Cesàro polynomials

The main object of this paper is to investigate several general families of hypergeometric polynomials and their associated multiple integral representations. By suitably specializing our main results, the corresponding integral representations are deduced for such familiar classes of hypergeometric polynomials as (for example) the generalized Bedient polynomials and the generalized Cesàro polynomials. Each of the integral representations, which are derived in this paper, may be viewed also as a linearization relationship for the product of two different members of the associated family of hypergeometric polynomials.