The experimental study of interaction between shock wave and turbulence

The interaction between shock wave and turbulence has been studied in supersonic turbulent mix layer wind tunnel. The interaction between oblique shock wave and turbulent boundary layer and the influence of large vortex in mix layer on oblique shock wave have been observed by NPLS technique. From NPLS image, not only complex flow structure is observed but also time-dependent supersonic flow visualization is realized. The mechanism of interaction between shock wave and turbulence is discussed based on high quality NPLS image.     

The c-myc coding DNA sequences of cyprinids （Teleostei： Cypriniformes）： Implications for phylogeny

The family Cyprinidae is one of the largest fish families in the world, which is widely distributed in East Asian, with obvious difference in characteristic size among species. The phylogeneUc analysis of cyprinid taxa based on the functionally important genes can help to understand the speciation and functional divergence of the Cyprinidae. The c-myc gene is an important gene regulating individual growth. In the present study, the sequence variations of the cyprinid c-myc gene and their phylogenetic significance were analyzed. The 41 complete sequences of the c-myc gene were obtained from cyprinids and outgroups through PCR amplification and clone. The coding DNA sequences of the c-myc gene were used to infer molecular phylogenetic relationships within the Cyprinidae. Myxocyprinus asiaticus （Catostomidae）, Misgurnus anguillicaudatus （CobiUdae） and Hemimyzon sinensis （Homalopteridae） were assigned to the outgroup taxa. Phylogenetic analyses using maximum parsimony （MP）, maximum likelihood （ML）, and Bayesian retrieved similar topology. Within the Cyprinidae, Leuciscini and Barbini formed the monophyletic lineage respectively with high nodal supports. Leuciscini comprises Xenocyprinae, CuItrinae, East Asian species of Leuciscinae and Danioninae, Gobioninae and Acheilognathinae, and Barbini contains Schizothoracinae, Barbinae, Cyprininae and Labeoninae. Danio rerio, D. myersi and Rasbora trilineata were supposed to separate from Leuciscinae and Barbini and to form another lineage. The positions of some Danioninae species were still unresolved. Analyses of both amino acid variation with parsimony information and two high variation regions indicated that there is no correlation between variations of single amino acid or high variation regions and characteristic size of cyprinids. In addition, the species with smaller size were usually found to be basal within clades in the tree, which might be the results of the adaptation to the primitive ecology and survival pressure.     

兰州市应用空气源热泵的可行性及对空气质量的改善

从兰州市的气候条件和国内外学者对低温热泵的试验和研究以及有关的工程实例等方面论述了在兰州城区采用空气源热泵进行取暖和空调是可行的。它为进一步减少兰州城区的空气污染,改善空气质量、节约水资源和电力资源提供了一种新的思路,值得在兰州市城区试验、推广这一高效、节能、环保的采暖空调技术。     

Al2O3-SiC复相陶瓷凝胶注模成型工艺因素的研究

研究了凝胶注模成型的各种工艺因素对Al2O3-SiC复相陶瓷悬浮体的黏度和固化时间的影响。结果表明：控制溶液的pH值为7～8时，采用2％（wB）的ADS1分散剂，可制备出固相体积分数为60％，黏度为640mPa·s的悬浮体；随成型温度的升高，悬浮体的固化时间逐渐缩短；随着引发剂尤其是催化剂加入量的增加，悬浮体的固化时间明显缩短。     

基于改进的Zernike不变矩的图像重建

简要介绍了描述图像形状特征的Zernike不变矩，在给出Zernike不变矩定义的基础上，讨论了Zernike不变矩的改进，指出可以使用基于改进的Zernike不变矩的形状特征数据来重建图像；基于改进的Zernike不变矩进行图像重建的实验，结果证明了对其进行改进的可行性。     

形式概念分析及其应用进展

形式概念分析是一种数据挖掘工具,在机器学习,软件工程和信息获取等领域得到广泛应用。简要介绍了形式概念分析的基本概念,提出了具体的建格方法。     

浅谈项目实施阶段工程造价的有效控制

工程造价控制贯穿于建设项目的全过程，既要全面，又要有侧重点，更要行之有效。文章对此进行了阐述。     

Sierpinski的一个三角数猜想

基于三角数问题的研究目前非常活跃,最近,Bennett宣布解决了由Sierpinski提出的一个三角数猜想问题,本文指出了Bennett文中的错误,并利用Pell方程解的性质的Stormer定理以及Bilu, Hanrot和Voutier的关于本原素因子的深刻结论, 证明了在一列几何级数中, 不存在4个相异的三角数, 完整地解决了Sierpinski的问题.     

再谈公务文书的模糊语言运用

模糊语言在公务文书一定的语言环境里,恰当运用可以收到良好的效果:使文字简炼,概括周密;回避一些直说不便,不说亦不行的棘手问题;对一些难以预测的事物和尚未命名的现象进行表述,说话留有余地。     

在数据库开发中遇到的数据保密问题

数据库的安全问题一直是数据库的开发者以及使用者非常关心和重视的问题,这是个非常难解的问题。开发者在开发时容易产生一些相应的问题,而无法确保数据的安全性,我们针对我们在开发系统时遇到的几个问题作了以下分析。