压缩半导体激光器光斑的光路分析及数值计算

由于半导体激光器的发散角大，输出光束为椭圆高斯光束，若应用于实际必须解决半导体激光器高斯光束的准直和光斑校正的问题。利用高斯光束理论对压缩半导体激光器发散角的问题进行了讨论，并且给出了数值分析。     

Aian origin for Polystichum (Dryopteridaceae) based on rbcL sequences

~~Aian origin for Polystichum (Dryopteridaceae) based on rbcL sequences~~     

Complete mitochondrial DNA sequence of Chinese alligator,Alligator sinensis, and phylogeny of crocodiles

The 16746-neueleotide (nt) sequence of mitochondrial DNA(mtDNA) of Chinese alligator,Alligator sinensis,was determined using the Long-PCR and primer walking methods.As is typical in vertebrates,the mtDNA encodes 13 proteins,2 rDNA,22 tRNA genes,and a noncoding control region.The Composition of bases is respectively 29.43%A,24.59%T,14.86%G,31.12% C.The gene arrangement differs from the common vertebrate gene arrangement,but is similar to that of other crocodiles,DNA sequence data from 12S rRNA,168 rRNA,protein-coding genes and combined sequence data were used to reconstruct the phylogeny of reptiles with the MP and ML methods.With this large data set and an appropriate range of outgroup taxa,the authors demonstrate that Chinese alligator is most closely related to American alligator among three crocodilian species,which suppors the traditional viewpoint.According to the branch lengths of ML tree from the combined data set,the primary divergence between Alligator and Caiman genus was dated at about 74.9 Ma,the split between Chinese alligator and American alligator was dated at 50.9Ma.     

平滑l0范数约束的β NMF及其在聚类中的应用

针对基因表达数据噪声大、冗余性较高,传统的NMF算法在基因表达数据聚类中的低效性问题,提出了一种平滑的l_0范数约束的β散度的矩阵分解与K-means相结合的聚类算法,应用到基因表达数据当中;将平滑的l_0范数约束引入到基于β散度的矩阵分解的目标函数中,从而提取有用特征信息用于聚类;最后通过实验比较,改进的算法平均聚类精度达到70%,比传统的NMF聚类算法精度提高了11%,聚类效果相较其他方法显著。     

非稳恒电磁场的数学表达的新形式

基于电磁作用的有限传播速率性质探讨了非稳恒电磁场的内在规律,通过对平面带电板的充电过程和对螺线管的通电过程中附近电磁场的变化规律的数学分析,说明经典电磁学理论中关于电场和磁场的散度的描述在非稳恒电磁场中并不正确,推导出在非稳恒电磁场中由于电磁作用的有限传播速率而产生的电场强度矢量的散度和旋度的公式以及磁场强度矢量的散度和旋度的公式,引进了电位移电荷,电位移磁荷,磁位移电荷和磁位移磁荷等新的电磁学概念,给出了相应的体密度公式,给出了描述非稳恒电磁场的两个守恒公式,最后给出了新的电磁学方程组的数学表达式．     

判别正项级数敛散性的一种方法

给出了一种判别正项级数敛散性的方法.     

河南省小康水平实现程度差异研究

河南省是我国的一个农业大省也是我国第一人口大省,河南省小康水平的发展直接影响着我国小康总体水平的发展。20世纪90年代中期以来,河南省小康水平发展取得长足进展,本文采用综合评分和综合指数相结合的方法,评价了河南省各县小康水平,并对比分析了河南省小康水平的县际差异,揭示产生这些差异的原因,最后提出提高河南省县级小康水平的具体策略。     

Valuable information in early sales proxies: The use of Google search ranks in portfolio optimization

We extract information on relative shopping interest from Google search volume and provide a genuine and economically meaningful approach to directly incorporate these data into a portfolio optimization technique. By generating a firm ranking based on a Google search volume metric, we can predict future sales and thus generate excess returns in a portfolio exercise. The higher the (shopping) search volume for a firm, the higher we rank the company in the optimization process. For a sample of firms in the fashion industry, our results demonstrate that shopping interest exhibits predictive content that can be exploited in a real‐time portfolio strategy yielding robust alphas around 5.5%.     

企业群落生态化演进动力机制的比较

采用系统线性和非线性演化两种观点对企业群落生态化演进机制进行了比较研究。研究发现,作为复杂的经济社会系统,企业群落生态化进程实质属于系统非线性演化,相比系统线性演化的唯一收敛平衡态——“所有企业最终都将演变为生态型”而言,系统非线性演化所产生的“分岔”效应具有现实意义,即混合状态(生态型与非生态型以一定比例混合存在)是系统演化所产生的稳定平衡点,而系统单向收敛至一种平衡态(全部企业为生态型或非生态型)则不稳定,且脱离生态工业实践。研究结果对于系统、科学地制定工业生态化政策具有重要的意义。     

明胶胶凝过程中的流变力学性质研究

本文研究了明胶胶凝过程中的流变力学性质,发现粘滞系数η与切速 r 有幂律关系;在胶凝发展过程中,指数 n 从0逐渐变化到胶凝点 x=-1/2.还发现η按∈~(-k)发散,在 f=0.005Hz 条件下,实验测得 k=1.48,而幂律发散范围为0.1—0.2≤∈≤0.6—0.7,随着浓度增加,幂律发散范围减小。