Interaction of CO with hydrous ruthenium oxide and development of a chemoresistive ambient CO sensor

Hydrated ruthenium oxide (RuO_x(OH)_y), the material of interest in this study was prepared by reaction of an aqueous solution of ruthenium chloride with base. This material was amorphous, made up of 20-50 nm particles and contains Ru(III) and Ru(IV), as determined by X-ray photoelectron spectroscopy. The conductivity of thick films of RuO_x(OH)_y decreased in the presence of CO in a background of air and this change was reversible. Infrared spectroscopy showed the formation of carbonates in the presence of CO, which disappeared upon replacement of CO with O₂. Upon heating RuO_x(OH)_y, there was a gradual conversion to crystalline RuO₂ beyond 200 °C. With these heated materials, the resistance change in the presence of CO at room temperature also gradually diminished. We propose that oxidation of CO on RuO_x(OH)_y leads to reduction of the ruthenium and a decrease in conductivity. With the conversion to crystalline RuO₂ upon heating, the material becomes metallic and conductivity changes are diminished. The change in conductivity of RuO_x(OH)_y with CO provides a convenient platform for an ambient CO sensor. Such a device also does not show interference from hydrocarbons (2000 ppm), ammonia (150 ppm), CO₂ (2000 ppm), NO (15 ppm) and NO₂ (15 ppm).     

搜索引擎PageRank算法的改进

为了解决企业快速决策时信息检索的问题,提出一种改进的PageRank算法。在考虑网页产生时间因素的同时,通过锚文本与网页主题的相似度分析按权重分配网页各正向链接PageRank值,产生的PageRank值更贴合主题搜索引擎的要求,并保持算法的简洁性。实验结果证明该改进算法能有效减少主题漂移现象,恰当提升新网页PageRank值。     

A quick tour on suffix arrays and compressed suffix arrays

Suffix arrays are a key data structure for solving a run of problems on texts and sequences, from data compression and information retrieval to biological sequence analysis and pattern discovery. In their simplest version, they can just be seen as a permutation of the elements in {1,2,…,n}, encoding the sorted sequence of suffixes from a given text of length n, under the lexicographic order. Yet, they are on a par with ubiquitous and sophisticated suffix trees. Over the years, many interesting combinatorial properties have been devised for this special class of permutations: for instance, they can implicitly encode extra information, and they are a well characterized subset of the n! permutations. This paper gives a short tutorial on suffix arrays and their compressed version to explore and review some of their algorithmic features, discussing the space issues related to their usage in text indexing, combinatorial pattern matching, and data compression.     

中英文文本分类系统异同因素的探讨

论文介绍了文本分类技术的研究进展及发展方向,给出了中英文文本分类系统构建的一般模型和过程,分析总结了中英文文本分类过程中的异同,并介绍了针对这些异同因素常用的处理方法。     

一个交通规划场景漫游系统

文章所述的交通规划场景漫游系统可根据平面交通规划方案生成三维仿真规划场景,并允许用户实时地漫游其中以观察规划效果,从而简化了规划流程,提高了劳动效率。文中介绍了系统的总体结构、操作流程和核心数据结构,同时着重讨论了系统中的体影分离渲染、不完全场景空间分割、四叉树结构的场景管理模式等多项关键算法技术。     

一种基于聚类的空间数据知识获取算法

本文提出了一个针对空间数据库基于聚类的知识获得取算法,该算法可解决空间的数据的聚类问题。     

Automatic verification for a class of distributed systems

Summary. The paper presents a new analysis method for a class of concurrent systems which are formed of several interacting components with the same structure. The model for these systems is composed of a control process and a set of homogeneous user processes. The control and user processes are modeled by finite labeled state transition systems which interact by means of enabling functions and triggering mechanisms. Based on this structure, an analysis method is presented which allows system properties, derived by reachability analysis for a finite number of user processes, to be generalized to an arbitrary number of user processes. A procedure for the automatic verification of properties such as mutual exclusion and absence of deadlocks is presented and is then used to provide for the first time a fully automated verification of the Lamport's fast mutual exclusion algorithm. Received: October 1998/Accepted January 2000     

Automatic transaction of signal via statistical modeling

The statistical information processing can be characterized by the likelihood function defined by giving an explicit form for an approximation to the true distribution. This mathematical representation, which is usually called a model, is built based on not only the current data but also prior knowledge on the object and the objective of the analysis. Akaike^2,3) showed that the log-likelihood can be considered as an estimate of the Kullback-Leibler (K-L) information which measures the similarity between the predictive distribution of the model and the true distribution. Akaike information criterion (AIC) is an estimate of the K-L information and makes it possible to evaluate and compare the goodness of many models objectively. In consequence, the minimum AIC procedure allows us to develop automatic modeling and signal extraction procedures. In this article, we give a simple explanation of statistical modeling based on the AIC and demonstrate four examples of applying the minimum AIC procedure to an automatic transaction of signals observed in the earth sciences. Genshiro, Kitagawa, Ph.D.: He is a Professor in the Department of Prediction and Control at the Institute of Statistical Mathematics. He is currently Deputy Director of the Institute of Statistical Mathematics and Professor of Statistical Science at the Graduate University for Advanced Study. He obtained his Ph.D. from the Kyushu University in 1983. His primary research interests are in time series analysis, non-Gaussian nonlinear filtering, and statistical modeling. He has published over 50 research papers. He was awarded the 2nd Japan Statistical Society Prize in 1997. Tomoyuki Higuchi, Ph.D.: He is an Associate Professor in the Department of Prediction and Control at the Institute of Statistical Mathematics. He is currently an Associate Professor of Statistical Science at the Graduate University for Advanced Study. He obtained his Ph.D. from the University of Tokyo in 1989. His research interests are in statistical modeling of space-time data, stochastic optimization techniques, and data mining. He has published over 30 research papers.     

学校网络机房故障与维修分析

从目前来看,学校网络机房的管理中管理者更多关注的是技术上的维护和保障工作,缺乏维修理念、缺乏对故障信息、维修信息的系统分析、缺乏对维修的效一费分析以及有效度的分析,因此,网络机房的维修工作存在着盲目性,缺乏计划性和目标性。所以应加强网络机房的科学化管理,加强对机房故障信息的统计分析,预防并减少故障,改善网络机房设备的技术状态;加强可靠性为主的维修理念,提高机房维修的有效度,确保机器本身的正常运转,延长使用寿命,更保障教学的顺利进行：本文通过对网络机房故障信息和维修信息的记录分析,得出对机房故障、维修方面有实效性的管理措施和对策。     

The <Emphasis Type="Italic">B</Emphasis><Superscript><Emphasis Type="Italic">dual</Emphasis></Superscript>-Tree: indexing moving objects by space filling curves in the dual space

Existing spatiotemporal indexes suffer from either large update cost or poor query performance, except for the B ^x -tree (the state-of-the-art), which consists of multiple B ⁺-trees indexing the 1D values transformed from the (multi-dimensional) moving objects based on a space filling curve (Hilbert, in particular). This curve, however, does not consider object velocities, and as a result, query processing with a B ^x -tree retrieves a large number of false hits, which seriously compromises its efficiency. It is natural to wonder “can we obtain better performance by capturing also the velocity information, using a Hilbert curve of a higher dimensionality?”. This paper provides a positive answer by developing the B ^dual -tree, a novel spatiotemporal access method leveraging pure relational methodology. We show, with theoretical evidence, that the B ^dual -tree indeed outperforms the B ^x -tree in most circum- stances. Furthermore, our technique can effectively answer progressive spatiotemporal queries, which are poorly supported by B ^x -trees.