Existence of limit cycles in general planar piecewise linear systems of saddle–saddle dynamics

The existence and number of limit cycles in a class of general planar piecewise linear systems constituted by two linear subsystems with saddle–saddle dynamics are investigated. Using the Liénard-like canonical form with seven parameters, the parametric regions of the existence of limit cycles are given by constructing proper Poincaré maps. In particular, the existence of at least two limit cycles is proved and some parameter regions where two nested limit cycles exist are given.     

两服务商竞争的研发外包知识转移信息披露决策

针对两服务商竞争的研发外包知识转移,考虑两个服务商知识吸收能力、信息获取能力均不同,且信息劣势方不知道信息优势方的知识吸收能力。通过建立以企业为领导者,两个服务商为跟随者的Stackelberg主从博弈模型,研究了企业和信息优势方的知识吸收能力披露决策,以及信息劣势方的信息处理决策,并用算例对结论加以说明。研究表明:仅当知识吸收能力较弱的服务商索取的单位报酬相对较低时,企业应披露信息优势方的知识吸收能力;仅当信息优势方知识吸收能力较弱时,其应披露自身知识吸收能力;信息劣势方应始终遵循信息优势方的信息披露策略;各方信息披露决策对企业和服务商均有不同影响。     

VaR测度下的风险对冲策略研究

本文分别在正态分布和任意分布设定下讨论最小在险价值(VaR)的风险对冲问题。在正态分布设定下,本文深入讨论最小方差对冲比率和最小VaR对冲比率的性质,并得出最小VaR对冲策略下组合收益率的均值和方差大于最小方差策略下组合收益率的均值和方差。在任意分布设定下,本文构建一种新的VaR对冲模型,该模型引入非参数核估计方法对VaR进行估计,然后基于VaR核估计量建立风险对冲问题,实现风险估计与风险对冲同步进行。实证结果非常稳健地表明,不做任何分布假设下的核估计法得到的风险对冲效果优于最小方差对冲策略和正态分布设定下的最小VaR对冲策略。     

Strategy for deciding between the use of single or biphasic systems as media for biocatalytic transformations using chemical equilibrium analysis

A theoretical model is derived to decide whether biphasic systems or single-phase aqueous systems are chosen as the media for microbial transformations. The yield ratio and product ratio at chemical equilibrium, which depend on the partition coefficients, equilibrium constants, activity coefficients and initial concentrations, are proposed as appropriate indices by the analysis of four common types of biochemical reaction under two extreme initial conditions.     

右半平面解析的Laplace-Stieltjes变换的广义级与型

给出右半平面解析的Laplace-Stieltjes变换的广义级与广义型的定义,研究了最大模M_u(σ,F)=sup{|∫_0~x e~(-(σ+it)y)dv(y)|:x∈(0,+∞),t∈R},最大项μ(σ,F)=max_(n∈N){A_n~*e~(-λnσ)},最大项指标v(σ,F)=max_k{λ_k|μ(σ,F)=A_k~*e~(-λkσ)}及其系数之间的关系,推广了Dirichlet级数的相关结果.     

Blow up of Solutions for a Nonlinear Petrovsky Type Equation with Time-dependent Coefficients

Acta Mathematicae Applicatae Sinica, English Series - In this paper, we study a nonlinear Petrovsky type equation with nonlinear weak damping, a superlinear source and time-dependent coefficients...     

A Fluorescent Cadmium-organic Framework Constructed by m-Thioacetatebenzoic Acid

Reactions of Cd(OAC)2·2H2O with m-thioacetatebenzoic acid(H2L) and 1,10-phenanthroline(phen) give rise to a metal-organic framework,[CdL(phen)]n(1).X-ray single-crystal diffraction reveals that 1 crystallizes in the monoclinic system,space group C2/c,with a= 25.7099(5),b=10.3872(2),c=19.1820(4),β=131.114(1)°,V=3859.4(1)3,Mr=502.80,Z= 8,F(000)=2000,μ=1.271 mm-1,Dc=1.731 g·cm-3,the final R=0.0226 and wR=0.0559 for 3817 observed reflections(Ⅰ > 2σ(Ⅰ)).1 displays a 1D double-strand chain structure with crab-like dinuclear subunits,and extends into a 3D network by π-π interactions and C-H···O hydrogen bonds.Photoluminescence studies reveal that it displays intense structure-related fluorescent emission bands(λex=342 nm) at 370.5 and 389 nm in the solid state at room temperature.     

求全局最优化问题的一类单参数全局凸填充函数

讨论求全局最优化问题的填充函数法,进一步提出了求全局最优化问题的一类单参数全局凸填充函数,它和目标函数同阶可微.     

On finite long run costs and rewards in infinite Markov chains

Conditions for the finiteness of long run costs and rewards associated with infinite recurrent Markov chains that may be discrete or continuous in time are considered. Without resorting to results from the theory of Markov processes on general state spaces we provide instructive proofs in the course of which we derive auxiliary results that are of interest in themselves. Potential applications of the finiteness conditions are outlined in order to elucidate their high practical relevance.