Stochastic Nicholson’s blowflies delayed differential equations

In this paper, we consider a class of stochastic Nicholson’s blowflies delayed differential equations. Firstly, we obtain the existence and uniqueness of the global positive solution with nonnegative initial conditions. Then the ultimate boundedness in mean of solution is derived under the same condition. Moreover, we estimate the sample Lyapunov exponent of the solution, which is less than a positive constant. In the end, an example with its numerical simulations is carried out to validate the analytical results.     

粘性依赖于温度的MHD方程组整体经典解的正则性

本文主要研究可压缩非等熵平面磁流体动力学方程组的Cauchy问题整体经典解的正则性,其中方程组的粘性系数λ,μ,磁扩散系数η和热传导系数κ都是比容v和温度θ的函数,正比于h(v)θα,h是满足一定条件的非退化光滑函数.在正则性准则■的条件下,当α适当小时,我们证明了大初值整体经典解的存在性.     

A Construction of Variable Strength Covering Arrays

Covering arrays(CA)of strength t,mixed level or fixed level,have been applied to software testing to aim for a minimum coverage of all t-way interactions among components.The size of CA increases with the increase of strength interaction t,which increase the cost of software testing.However,it is quite often that some certain components have strong interactions,while others may have fewer or none.Hence,a better way to test software system is to identify the subsets of components which are involved in stronger interactions and apply high strength interaction testing only on these subsets.For this,in 2003,the notion of variable strength covering arrays was proposed by Cohen et al.to satisfy the need to vary the size of t in an individual test suite.In this paper,an effective deterministic construction of variable strength covering arrays is presented.Based on the construction,some series of variable strength covering arrays are then obtained,which are all optimal in the sense of their sizes.In the procedure,two classes of new difference matrices of strength 3 are also mentioned.     

涉及导数与差分的亚纯函数的小函数的收敛指数与级

设f(z)是一个复平面上的亚纯函数,c是一个非零有穷复数,a(z)是f(z)的一个小函数,本文研究f(z)a(z),f(z+c)-a(z)及△c^nf(z) a(z)(n∈N^+)的零点收敛指数与f(z)的级之间的关系.由此改进了涉及导数与差分的亚纯函数值分布的一些相关结果.     

国家治理体系完善能抑制企业盈余管理吗？——基于准自然实验的经验证据

本文以沪深A股上市公司为研究对象,从巡视监督的视角考察了国家治理体系完善的公司治理效应。研究结论表明:巡视监督能够有效的抑制企业盈余管理,降低24%的应计盈余管理和22%的真实盈余管理。采用平行趋势检验、安慰剂检验和倾向得分法之后的结论依然稳健;相对于地方巡视监督而言,中央巡视监督对企业盈余管理治理的效果更为显著;巡视监督对于腐败地区企业盈余管理治理效应更强。本文丰富了国家治理体系发挥公司治理效应的文献体系,揭示了制度建设在实体经济发展中的重要作用。     

非单调滤子曲率线搜索算法解无约束非凸优化

宇和濮在文[Yu Z S,Pu D G.A new nonmonotone line search technique for unconstrained optimization[J].J Comput Appl Math,2008,219:134-144]中提出了一种非单调的线搜索算法解无约束优化问题.和他们的工作不同,当优化问题非凸时,本文给出了一种非单调滤子曲率线搜索算法.通过使用海森矩阵的负曲率信息,算法产生的迭代序列被证明收敛于一个满足二阶充分性条件的点.在不需要假设极限点存在的情况下,证明了算法具有整体收敛性,而且分析了该算法的收敛速率.数值试验表明算法的有效性.     

Epidemic phase and the site percolation with distant-neighbor interactions

A generalized site percolation model is used to construct an analogy with the epidemic problem, involving spatial coordinates. Epidemic phase and concepts like herd immunity are analyzed in terms of connectivity in a 2D square lattice. The epidemic model used in this work considers a specific interaction topology that includes up to the fifth-nearest neighbors. The results, obtained by Monte Carlo simulation, emphasize the meaning of the spatial coordinates and are illustrated by an epidemic/non-epidemic phase diagram.