带有不等式约束的全局最优性条件

本文利用不连续罚函数方法将带有不等式约束的全局优化问题的求解转化为 讨论一非线性方程的求根问题,从而得到若干个全局最优性条件.     

PERSISTENCE AND GLOBAL STABILITY FOR TWO-SPECIES NONAUTONOMOUS PREDATOR-PREY SYSTEM WITH DIFFUSION AND TIME DELAY

In this paper, a non-autonomous predator-prey model with diffusion andcontinuous time delay is studied, where the prey can diffuse between two pat-ches of a heterogeneous environment with barriers between patches, but for thepredator, the diffusion does not involve a barrier between patches, further itis assumed that all the parameters are time-dependent. It is shown that thesystem can be made persistent under some appropriate conditions. Moreover,sufficient conditions that guarantee the existence of a unique periodic solutionwhich is globally asymptotic stable are derived.     

Synthesis and herbicidal activity of O,O-dialkyl phenoxyacetoxyalkylphosphonates containing fluorine

A series of substituted phenoxyacetoxyalkylphosphonates bearing fluorine were designed and synthesized. All the new compounds were identified by elemental analysis, IR, ¹H NMR and MS and were tested for herbicidal activity in greenhouse at a rate of 1.5 kg/ha. The results of preliminary bioassay showed that fluorine moiety introduced to the core structure could help to improve the herbicidal activity, and compounds with a 3-trifluoromethyl in benzene ring exhibited higher inhibitory activity.     

激光二极管侧面抽运Nd:YAG锁模激光器的研究

利用谐振腔的稳定条件对激光二极管侧面抽运的Nd：YAG锁模直腔的稳区特性和谐振腔内的光斑分布进行了分析。根据对腔参量的分析，选取合适的腔参量设计了一个简单的侧面抽运直腔，该谐振腔腔形简单，没有像散，振荡光模式好，有利于激光器的锁模运转。实验中采用国内自行研制的半导体可饱和吸收镜，实现了激光二极管侧面抽运半导体可饱和吸收镜锁模Nd：YAG激光器的连续锁模运转，平均输出功率为2W，锁模脉冲宽度为10ps，重复频率为100MHz。结合实验结果进一步讨论了半导体可饱和吸收镜的一些参量如饱和恢复时间、调制深度等对实现稳定连续锁模的影响。     

Head-group-influenced mixed micellization of sodium deoxycholate with conventional hydrocarbon surfactants of identical hydrocarbon tails

Conductivity, viscosity, turbidity, and NMR measurements were performed over most of the mole fraction range for sodium deoxycholate (SDC) with hexadecyltrimethylammonium bromide (HTAB), hexadecylpyridinium bromide (HPyBr), and hexadecylpyridinium chloride (HPyCl). All studies demonstrate that the mixed-micelle formation is more favorable in SDC plus HTAB rather than SDC plus HPyBr or SDC plus HPyCl mixtures. The results showed that the bulky pyridinium head groups of HPyBr or HPyCl create steric incompatibility with rigid SDC monomers in the mixed state.     

Separation in distributive congruence lattices

We define separable sets in algebraic lattices. For a finitely generated congruence distributive variety V \mathcal{V} , we show a close connection between non-separable sets in congruence lattices of algebras in V \mathcal{V} and the structure of subdirectly irreducible algebras in V \mathcal{V} . We apply the general results to some lattice varieties.     

Fixed Point Theorems on Product Topological Spaces and Applications

A new collectively fixed point theorem for a family of set-valued mappings defined on product spaces of non-compact topological spaces without linear structure is proved and some special cases are also discussed. As applications, some non-empty intersection theorems of sets with convex sections and equilibrium existence theorem of abstract economies are obtained under much weaker assumptions. Our results includes a number of known results as many special cases.     

凸规划的极大熵函数序列及其收敛性

为了消除凸规划问题中极大熵方法所导致的数值病态，该文应用Lagrange乘子法及赋范原理，给出一类凸规划问题的极大熵函数序列，并证明该序列一致收敛于凸规划的最优解。     

Tuning inventory policy parameters in a small chemical company

A project to improve inventory management in a small UK chemical company is described. A research group comprising university academics and company managers for logistics and information technology examined current practices and analysed a database of historical records of business operations of the company. Based on the analysis, a scheme to categorise stock and set ordering policies to optimise inventory costs was developed. Some comments are made on process issues and the learning that took place.