System combination and score normalization for spoken term detection

Spoken content in languages of emerging importance needs to be searchable to provide access to the underlying information. In this paper, we investigate the problem of extending data fusion methodologies from Information Retrieval for Spoken Term Detection on low-resource languages in the framework of the IARPA Babel program. We describe a number of alternative methods improving keyword search performance. We apply these methods to Cantonese, a language that presents some new issues in terms of reduced resources and shorter query lengths. First, we show score normalization methodology that improves in average by 20% keyword search performance. Second, we show that properly combining the outputs of diverse ASR systems performs 14% better than the best normalized ASR system. © 2013 IEEE.

Bibliometric analysis of nicotine research in China during the period of 1991 to 2007

With the widespread exposure of people to nicotine through recreational use of tobacco products, research into nicotine has attracted increasing attention. Tobacco smoking is by far the most important cause of lung cancer. As the world's largest producer and consumer of tobacco products, China bears a large proportion of the global burden of smoking-related disease; therefore, information on nicotine publications should be collected to formulate future research policy. In the present study, we investigated nicotine-related research articles published by Chinese authors that were indexed in the Science Citation Index (SCI) from 1991 to 2007. An indicator "citations per publication" (CPP) was used in the study to evaluate the impact of journals, articles, and institutes. The quantity of publications has increased at a quicker pace than the worldwide trend. Article visibility, measured as the frequency of being cited, also increased during the period. However, the overall quality of articles, based on the impact factor of journals publishing those articles, dropped behind the worldwide average level. There has been an increase in international collaboration, mainly with researchers in the USA. The average CPP of international co-authorship articles was higher than that of single country publications. Besides the USA, nicotine research in China will benefit from more collaboration with Taiwan, England, and Germany. Some 110 of 264 articles were published by a single institute, and the top six institutes were compared from various angles. Seventy-two subject categories were covered, and trends (in terms of both quantity and quality) of nicotine research in China were compared with worldwide trends. In addition, analysis of keywords in both nicotine and lung cancer research fields was applied to indicate research interests. Mutual cooperation among multiple disciplines needs further strengthening.

Electric-tunable magneto resistance effect in a two-dimensional electron gas modulated by hybrid magnetic-electric barrier nanostructure

The electric-tunable spin-independent magneto resistance effect has been theoretically investigated in ballistic regime within a two-dimensional electron gas modulated by magnetic-electric barrier nanostructure. By including the omitted stray field in previous investigations oil analogous structures, it is demonstrated based on this improved approximation that the magnetoresistance ratio for the considered structure can be efficiently enhanced by a proper electric barrier up to the maximum value depending on the specific magnetic suppression. Besides, it is also shown the introduction of positive electrostatic modulation can effectively overcome the degradation of magnetoresistance ratio for asymmetric configuration and enhance the visibility of periodic pattern induced by the size effect, while for an opposite modulation the system magnetoresistance ratio concerned may change its sign. (C) 2009 Elsevier B.V. All rights reserved.

Theory and experiment of two-photon 'direct' interference for type-II spontaneous parametric down-conversion with an ultrafast pulse laser pump

Fourth-order spatial interference of entangled photon pairs generated in the process of spontaneous parametric down-conversion pumped by a femtosecond pulse laser has been performed for the first time. In theory, it takes into account the transverse correlation between the two photons and is used to calculate the dependence of the visibility of the interference pattern obtained in Young's double-slit experiment. In this experiment, a short focal length tens and two narrow band interference filters were adopted to eliminate the effects of the broadband pump laser and improve the visibility of the interference pattern under the condition of nearly collinear light and degenerate phase matching.

Spatial interference effect of two-photon in femtosecond-pulse pumped spontaneous parametric down-conversion

We have used the transverse correlated properties of the entangled photon pairs generated in the process of spontaneous parametric down-conversion, which is pumped by a femtosecond pulse laser, to perform Young's interference experiment. Unlike the case of a continuous wave laser pump, a broadband pulse laser pump can submerge an interference pattern. In order to obtain a high visibility interference pattern, we used a lens with a tunable focal length and two interference filters to eliminate the effects of the broadband pump laser. It is proven that the process of two-photon direct interference is a post-selection process.

Range-Gated Laser Stroboscopic Imaging for Night Remote Surveillance

For night remote surveillance, we present a method, the range-gated laser stroboscopic imaging(RGLSI), which uses a new kind of time delay integration mode to integrate target signals so that night remote surveillance can be realized by a low-energy illuminated laser. The time delay integration in this method has no influence on the video frame rate. Compared with the traditional range-gated laser imaging, RGLSI can reduce scintillation and target speckle effects and significantly improve the image signal-to-noise ratio analyzed. Even under low light level and low visibility conditions, the RGLSI system can effectively work. In a preliminary experiment, we have detected and recognized a railway bridge one kilometer away under a visibility of six kilometers, when the effective illuminated energy is 29.5 mu J.

Satellite Constellation Design for Complex Coverage

Most traditional satellite constellation design methods are associated with a simple zonal or global, continuous or discontinuous coverage connected with a visibility of points on the Earth's surface. A new geometric approach for more complex coverage of a geographic region is proposed. Full and partial coverage of regions is considered. It implies that, at any time, the region is completely or partially within the instantaneous access area of a satellite of the constellation. The key idea of the method is a two-dimensional space application for maps of the satellite constellation and coverage requirements. The space dimensions are right ascension of ascending node and argument of latitude. Visibility requirements of each region can be presented as a polygon and satellite constellation as a uniform moving grid. At any time, at least one grid vertex must belong to the polygon. The optimal configuration of the satellite constellation corresponds to the maximum sparse grid. The method is suitable for continuous and discontinuous coverage. In the last case, a vertex belonging to the polygon should be examined with a revisit time. Examples of continuous coverage for a space communication network and of the United States are considered. Examples of discontinuous coverage are also presented.

支持属性粒度数据库加密的查询重写算法

DAS（databaseasaservice）模型数据库中采用加密方案的关键问题之一是针对密文关系的查询处理．DAS模型特有的体系结构和信任模型决定了加密解密操作只能在客户端进行，目前的方案普遍在元组粒度加密的基础上进行查询重写，不可避免地造成了加密效率的损失．为此，提出一种支持属性粒度加密方案的查询重写算法，利用关系代数公式对查询语句进行等价变换，将涉及加密属性的条件谓词与其他条件谓词分离，重构查询语句，支持任意层次的相关子查询．实验显示，算法能够降低客户端与服务器间的网络传输数据量，从而有效地缩短加密DAS模型数据库的查询执行时间．

基于查询分类的个性化检索系统研究

搜索引擎是网络用户最常用的网络服务之一。用户通过向搜索引擎提交查询（Query）的方式获取与该查询相关的信息。由于用户的背景各不相同，即使他们输入完全相同的查询语句，其需求也可能是不同的。传统的搜索引擎并没有针对用户来设计查询的相关度算法，因此难以给出令每个用户满意的结果。目前人们提出通过个性化检索技术来解决这一难题。而查询分类是个性化检索中最具挑战性的关键技术之一。 本文通过对大规模真实中文查询语句的分析，提出使用VASE特征词的方法对查询所属的主题进行分类，并采用规则的方法对用户的意图进行自动识别，实验结果表明该方法能够有效地对查询主题和用户意图进行识别。 随后本文探讨了如何使用查询分类的结果进行个性化检索。基于用户的点击信息和查询类别，分别采用对查询结果进行过滤、次级关键词的提取以及对不同的查询意图采用不同的排序算法等三种策略对检索的结果进行改进。实验结果表明这些方法都取得了良好的效果。 最后，本文设计并实现了客户端个性化检索工具，以Firefox浏览器插件的形式，对用户输入的查询进行分类，并基于百度的搜索结果并为用户提供个性化检索的功能。

dynamic evolutions based on ontologies

With the continuous changes in application requirements of the enterprises, Web resources must be updated, so do the underlying ontologies that are associated with the Web resources. In the situation, it is very challenging for ontological engineers to specify the changes of ontologies, keep their consistencies and achieve semantic query of Web resources based on the evolving ontologies. We propose a construct called Prioritized Knowledge Base (PKB) based on SHOQ(D) description logic, and discuss some properties of PKB.PKB can be used for describing the evolutions and updates of ontologies with conflicting information. Furthermore, we develop some algorithms for checking conflict rules and performing semantic query based on PKB.

A shortest path algorithm for moving objects in spatial network databases

One of the most important kinds of queries in Spatial Network Databases (SNDB) to support location-based services (LBS) is the shortest path query. Given an object in a network, e.g. a location of a car on a road network, and a set of objects of interests, e.g. hotels,gas station, and car, the shortest path query returns the shortest path from the query object to interested objects. The studies of shortest path query have two kinds of ways, online processing and preprocessing. The studies of preprocessing suppose that the interest objects are static. This paper proposes a shortest path algorithm with a set of index structures to support the situation of moving objects. This algorithm can transform a dynamic problem to a static problem. In this paper we focus on road networks. However, our algorithms do not use any domain specific information, and therefore can be applied to any network. This algorithm’s complexity is O(klog2 i), and traditional Dijkstra’s complexity is O((i + k)2).

基于对象关系的位置相关数据库模型及其移动持续查询处理策略

近年来，人们对位置相关的信息服务进行了较为大量的研究，这些工作主要以移动对象数据库及空间数据库框架为基础，探讨如何有效地支持位置相关的查询等问题．然而，另一类重要的数据类型——位置相关的数据(10cation dependent data，LDD)，却没有得到人们足够的重视．目前，LDD的研究主要集中在概念应用层，缺乏完善的数据库模型(包括数据类型及查询操作等)及有效的查询处理方法．为了解决上述问题，提出一种基于对象关系数据库模型的位置相关数据模型(object—relational database based LDD model，ORLDD)。在ORLDD中，定义了完整的位置相关数据类型及查询操作，给出了相关的移动持续查询处理方法，并阐述了在对象关系数据库系统PostgreSQL上的实现方法．实验结果表明，该方法具有良好的查询处理性能及灵活性．

移动对象在空间网络数据库上的kNN查询

中国计算机学会

移动对象数据库模型、查询语言及实时交通流分析

提出一种移动对象数据库模型——Dynamic Transportation Network Based Moving Objects Database(简称DTNMOD),并给出了DTNMOD中基于移动对象时空轨迹的网络实时动态交通流分析方法.在DTNMOD中,交通网络被表示成动态的时空网络,可以描述交通状态、拓扑结构以及交通参数随时间的变化过程;网络受限的移动对象则用网络移动点表示.DTNMOD模型包含了完整的数据类型和查询操作的定义,因此可以在任何可扩充数据库(如PostgreSQL或SECONDO)中实现,从而得到完整的数据库模型和查询语言.为了对相关模型的性能进行比较与分析,基于PostgreSQL实现了一个原型系统并进行了一系列的实验.实验结果表明,DTNMOD提供了良好的区域查询及连接查询性能.

利用构建语义词典的查询自动分类方法

为解决传统的文档分类方法和手工分类方法都不适宜于处理查询分类的问题,提出了一种基于Web的自动构建特定主题的语义词典的方法来分类搜索查询,通过基于主题的Web信息采集和bootstrapping,由某个主题的少量关键词逐步扩充,最终得到该主题的语义词典及词典中每个单词的相对词频.Web中信息的冗余和各主题语义上的差别使各主题的语义词典中单词的种类和数量存在很大差异,这种差异可以用来对用户的搜索查询进行分类.实验结果表明,利用语义词典可以较准确地将用户的查询分类,同时该分类方法基本上不需要人工介入,且可适应搜索查询覆盖面广和实时性强的特点,较好地解决了搜索查询分类的问题.