CS-Chord:基于聚类分离的分布式高维向量索引

M-Chord是一种基于P2P网络的高维向量索引,其聚类边缘的向量容易与搜索圆频繁相交,使得查找的区域增多,降低了M-Chord的效率。提出一种基于聚类分离的分布式高维向量索引(CS-Chord),将边缘区域的高频检索向量从Chord环中分离出来,集中存储在服务器上,中心区域的向量仍存储于Chord环中,节省了大量资源的定位时间,从而提高检索效率。实验结果表明:在查询半径为0.2时,CS-Chord距离计算次数约为2000,比M-Chord减少了约2500次;CS-Chord消息转发次数约降低150次,仅为M-Chord的50%。     

Conservative and aggressive rough SVR modeling

Support vector regression provides an alternative to the neural networks in modeling non-linear real-world patterns. Rough values, with a lower and upper bound, are needed whenever the variables under consideration cannot be represented by a single value. This paper describes two approaches for the modeling of rough values with support vector regression (SVR). One approach, by attempting to ensure that the predicted high value is not greater than the upper bound and that the predicted low value is not less than the lower bound, is conservative in nature. On the contrary, we also propose an aggressive approach seeking a predicted high which is not less than the upper bound and a predicted low which is not greater than the lower bound. The proposal is shown to use ?-insensitivity to provide a more flexible version of lower and upper possibilistic regression models. The usefulness of our work is realized by modeling the rough pattern of a stock market index, and can be taken advantage of by conservative and aggressive traders.     

The forwarding indices of augmented cubes

For a given connected graph G of order n, a routing R in G is a set of n(n−1) elementary paths specified for every ordered pair of vertices in G. The vertex (resp. edge) forwarding index of G is the maximum number of paths in R passing through any vertex (resp. edge) in G. Choudum and Sunitha [S.A. Choudum, V. Sunitha, Augmented cubes, Networks 40 (2002) 71-84] proposed a variant of the hypercube Qn, called the augmented cube AQn and presented a minimal routing algorithm. This paper determines the vertex and the edge forwarding indices of AQn as and ²n−1, respectively, which shows that the above algorithm is optimal in view of maximizing the network capacity.     

单苯环氯取代指数法预测二噁类化合物PCDDs的正辛醇/水分配系数

采用单苯环氯取代指数作为氯代二苯并二口恶口英类化合物 (PCDDs)的分子结构描述符 ,通过正向逐步线性回归方法建立了PCDDs的logKow与分子结构描述符之间的定量关系模型。与文献报道的MOD模型相比 ,该模型不仅具有显著的相关性 (n =43,Radj=0 898,SE =0 195 ,在α =0 0 5时 ,F =2 0 45 5 ,p =0 0 0 0 0 ) ,而且对于分子结构具有更好的区分能力。利用建立的模型 ,对没有logKow文献值的其他 33种PCDDs化合物给出了预测值     

基于心态指标的区间灰数关联度模型

针对已有的灰色关联度模型仅适用于实数序列而不能应用于区间灰数序列的情况,通过引入决策者心态指标,将区间灰数序列转化为决策者心态指标序列,并且当决策者的心态指标确定时,心态指标序列就转化为实数序列,于是通过对体现决策者心态的实数序列建立灰色关联度模型,得到了反映出决策者心态的灰色关联度,从而构建了基于心态指标的区间灰数关联度模型。决策者处于不同心态时,可以通过调整其心态计算灰关联度,从而使建立的关联度模型更加符合实际。最后,通过计算实例说明了模型的可行性。     

Development of a fish‐based index of biotic integrity (FIBI) for monitoring riverine ecosystems in the Lake Victoria drainage Basin,Kenya

The long term monitoring of aquatic ecosystems based on chemical analysis is expensive resulting in a lack of time series data for management purposes thus necessitating the need for new cost effective methodologies. This study developed a fish‐based index of biotic integrity (FIBI) for monitoring environmental conditions in riverine ecosystems within the Lake Victoria Basin, Kenya. The fish fauna in the basin is poorly studied, less diverse and ecologically specialized than the temperate fauna that provided the origins of the Index of Biotic Integrity. Fish samples were collected by electrofishing from 24 sites during baseflow periods in February, March and July 2004. Validation data were collected from 7 sites with varying levels of degradation. Fish samples were identified, counted and grouped into different trophic groups, relative tolerance to pollution, habitat guild and whether exotic or native to riverine environment. Thirty‐three candidate metrics were evaluated for responsiveness to habitat quality and twelve were selected for inclusion in the final index. The index classified 6 of the 7 validation sites according to their levels of degradation. As a bioassessment tool, the index was useful in laying the basis for long‐term monitoring of rivers in the Lake Victoria drainage basin. Copyright © 2010 John Wiley & Sons, Ltd.     

时空结构视野下旅游客源市场定量初探——以浙江嘉兴乌镇为例

在客源时间分布上,计算乌镇游客游览时间强度指数,得到游客游览时间主要集中在二、三季度,并以7、8月份为最高峰。而在客源市场的分布上,鸟镇已经形成了以浙江为核心,上海、北京等地为一级,安徽、河南等地为二级的国内客源市场。在长三角古村落旅游发展迅速的今天,乌镇与周边的周庄、同里等古镇的竞争日益激烈,而旅游产品的创新、加大宣传迅速占领国内二级客源市场等措施将有助于乌镇在竞争中脱颖而出,占领主导地位。     

Coinage Metals in the Nanometer Length Scale

Cetylpyridinium chloride (CPC)-stabilized gold organosol in toluene has been prepared by using a two-phase (water-toluene) extraction of AuCl₄^- followed by its reduction with sodium borohydride in the presence of the surfactant, CPC. The surfactant-stabilized gold nanoparticles were exploited to examine their optical properties when exposed to various solvent systems by measuring the changes in the localized surface plasmon resonance (LSPR) spectrum.     

Integrated Evaluation and Its Application on Decision-Making of Comprehensive Transportation Projects

The comprehensive transportation project involves with many different transportation methods, such as railway, highway, waterway, airline, and pipeline, which have their special characteristics. To evaluate the transportation project with different transportation methods under the same system, the integrated evaluation method should be built up on the basis of a common index system. This paper suggests a feasible integrated evaluation method including index system establishing, indices transacting, the index weight distributing, and weighted value integrating.     

252Cf中子活化核燃料棒235U富集度均匀性检测装置

采用^252Cf中子活化方法研制燃料棒^235U富集度均匀性检测设备，用慢化后的^252Cf中子照射燃料棒，使燃料棒UO2芯块中的^235U发生裂变，通过测量其裂变产物的γ射线总强度对燃料棒^235U富集度及其均匀性进行在线检测。采用1．2mg的^252Cf中子源，能检测出燃料棒中^235U富集度相对偏差土10％的单个混料芯块，单根燃料棒的检测速度可达7m/min，检测结果的置信概率为97．74％。