A competitive algorithm in searching for many edges in a hypergraph

We give a competitive algorithm to identify all d defective edges in a hypergraph with d unknown. Damaschke did the d=1 case for 2-graphs, Triesch extended the d=1 case to r-graphs, and Johann did the general d case for 2-graphs. So ours is the first attempt to solve the searching for defective edges problem in its full generality. Further, all the above three papers assumed d known. We give a competitive algorithm where d is unknown.     

二维随机激光器的模式选择及阈值与饱和特性

基于将Maxwell方程与四能级原子系统速率方程相结合而建立起随机激光时域理论，并利用有限时域差分法，研究了二维随机介质中激光模式的输出特性与介质尺寸、外形及抽运速率等参数的关系.结果表明，与传统激光模式相似，随机激光模式的强度随抽运速率的变化不仅具有阈值特性，而且具有饱和特性.基于模式特性对介质及抽运参数的依赖关系，提出了二维随机激光器的选模方式，在很大程度上不同于传统激光器的选模方式. 关键词： 随机激光器 模式选择 无序介质中的光学特性     

KNSBN晶体猫式互抽动相位共轭光特性

在KNSBN：Ce晶体中，利用二波耦合作用，在单一光束无法获得相位共轭光的条件下，实现了“猫”式互抽运相位共轭光输出，获得较高的共轭光发射率，实验结果表明，晶体的二波耦合作用可以使晶体的自抽运相位共轭光的阈值光强降低。入射光的入射角范围增大，响应时间缩短。     

股份制公司的综合投资方案决策模型

对股份制公司的综合投资方案的决策问题进行了研究.首先依据多个投资方案的风险与收益并存的实际情况,建立了最佳投资组合方案的多目标决策模型.然后,由董事会综合各股东所持股份和相互评价权值,利用群决策的方法得到一个最终投资方案,此方案在理论上能使公司获得最大收益.     

Pt(110)表面自吸附原子能量和力的改进分析型嵌入原子法分析

采用改进分析型嵌入原子法计算了Pt(110)表面自吸附原子的能量和法向力.当Pt吸附原子位于Pt(110)表面第一层原子的二重对称洞位上0.11nm时最稳定.Pt吸附原子的最佳迁移路径是由一个二重对称洞位沿密排方向迁移到最近邻的另一个二重对称洞位.在吸附原子远离表面的过程中，将依次经过排斥、过渡和吸引等三个区域.在排斥区和过渡区，由于吸附原子与表面原子间强的相互作用势，吸附原子的能量和法向力的形貌图均为(110)面原子排列的复形，与对势理论和嵌入原子法得到的结果一致.在吸引区，由于多体相互作用及晶体中原子 关键词： 金属表面 自吸附 能量 力     

新颖的PPLN电光开关

在分析基于级联二阶非线性效应的准相位匹配周期极化铌酸锂(PPLN)波导全光波长变换器的有关参量容限的基础上,提出PPLN波长变换器的电光调控设想,并给予简要论证,论证结果是可行的,从而可实施电控调谐来自动补偿其失配,进而也可实现光开关的功能 关键词： 准相位匹配 周期极化铌酸锂 波长变换 光开关 电光效应调控     

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.     

InAs/GaSb/AlSb resonant tunneling spin device concepts

We discuss device concepts for creating spin-polarized current sources without external magnetic fields, using non-magnetic 6.1 Å semiconductor resonant tunneling structures. Spin filters, spin pumps, and spin transistors that exploit structural and bulk inversion asymmetries will be examined.     

Melt rheology of polylactide/montmorillonite nanocomposites

In this article, the linear and nonlinear shear rheological behaviors of polylactide (PLA)/clay (organophilic‐montmorillonite) nanocomposites (PLACNs) were investigated by an Advanced Rheology Expanded System rheometer. The nanocomposites were prepared by master batch method using a twin‐screw extruder with poly(ε‐caprolactone) (PCL) as a compatibilizer. The presence of org‐MMT leads to obvious pseudo‐solid‐like behaviors of nanocomposite melts. The behaviors caused by the formation of a “percolating network” derived from the reciprocity among the strong related sheet particles. Therefore, the storage moduli, loss moduli, and dynamic viscosities of PLACNs show a monotonic increase with MMT content. Nonterminal behaviors exists in PLACNs nanocomposites. Besides the PLACNs melts show a greater shear thinning tendency than pure PLA melt because of the preferential orientation of the MMT layers. Therefore, PLACNs have higher moduli but better processibility compared with pure PLA. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 3189–3196, 2007