适用于高速长途DWDM系统的色散管理线路

对于高速长途密集波分复用（DWDM）传输，必需采用各种各样的色散补偿、色散管理技术，其中，交替使用正负色散光纤构成色散管理线路（DML）是可行的解决方案之一，在国际上已经取得显著进展，正成为人们关注的焦点，国内在这方面的研究报道还少见.文章以高速长途DWDM系统对传输线路的性能要求为基础，综述了有代表性的3种不同类型的DML的特点和最新进展。     

Municipal solid waste conversion to energy

In recent years it has been recognised by an increasing number of nations that there is considerable energy potential within MSW. As a result many countries have established R,D& D programmes to examine methods of exploiting this potential. The IEA's MSW Conversion Activity was set up in 1986 to provide an infrastructure for sharing information and co-ordinating work in this area internationally. This Activity was extended in 1989 and currently a total of 9 nations participate in it.

To cope with the wide scope of the area (encompassing both biological and thermal processing of MSW) the Activity was divided into three subgroups or Expert Working Groups (EWGs). Each of these dealt with a distinct area of expertise:

1. •Downstream effects of source separation and screening of MSW

2. •Sampling and analytical protocols

3. •Landfill gas

In addition to these groups a central secretariat based at Harwell (UK) has provided guidance, established and administered databases of contacts and produced a series of national reports.

This paper describes the achievements of the Activity and discusses work proposed for the future.     

煤与垃圾衍生燃料的流化床混烧试验研究

使用鼓泡流化床燃烧炉进行了煤与垃圾衍生燃料(RDF)的混烧实验研究,分析了燃烧尾气中O2、CO、CO2、H2O、NOx、CH4、SO2、HCl、HCN浓度的变化,并对各成分之间的浓度进行了相关性分析。研究结果表明在750~900℃的范围内,高温利于SO2的脱除;NO的浓度随床温的提高而增加,NO2的浓度与床温的关系不大;HCl的浓度随床温的升高而增加,说明高温不利于HCl的脱除;在空气量较低的情况下,CO、CH4、N2O、HCN等气体的浓度较高,相关分析表明,这些气体浓度之间有较强的正相关关系,说明这些气体适宜于还原气氛下生成;随着HCl气体浓度的增加,SO2浓度降低,说明HCl的存在可促进石灰石脱除SO2的反应,同时还证实煤与RDF混烧可使尾气中的SO2和HCl气体浓度均有所下降。     

P2P网络中基于RDF/S的数据库语义查询系统设计*

提出一种P2P网络环境下基于RDF/S 数据模型的数据库语义查询原型系统,可以有效地对各种基于ODBC的异构数据源进行语义查询。首先数据内容经RDF/S描述成RDF/S schema片断形式,然后对片段进行编码,再把编码杂凑到DHT中,就可以使用Chord协议定位目标节点。     

APPLICATION OF MAXIMUM ENTROPY METHOD TO CALCULATE RDF OF Ni-P AMORPHOUS ALLOY FROM X-RAY DIFFRACTION DATA

Experiments clarified that application of the maximum entropy method to calculate the RDF(radial distribution function)of the Ni-P amorphous alloy from fewer data of its X-raydiffraction data shows a higher resolution and good consistent with known results.It is be-lieved that this method is available for the analysis of amorphous structure.     

Measuring the structural similarity among XML documents and DTDs

Measuring the structural similarity between an XML document and a DTD has many relevant applications that range from document classification and approximate structural queries on XML documents to selective dissemination of XML documents and document protection. The problem is harder than measuring structural similarity among documents, because a DTD can be considered as a generator of documents. Thus, the problem is to evaluate the similarity between a document and a set of documents. An effective structural similarity measure should face different requirements that range from considering the presence and absence of required elements, as well as the structure and level of the missing and extra elements to vocabulary discrepancies due to the use of synonymous or syntactically similar tags. In the paper, starting from these requirements, we provide a definition of the measure and present an algorithm for matching a document against a DTD to obtain their structural similarity. Finally, experimental results to assess the effectiveness of the approach are presented.     

nSPARQL: A navigational language for RDF

Navigational features have been largely recognized as fundamental for graph database query languages. This fact has motivated several authors to propose RDF query languages with navigational capabilities. In this paper, we propose the query language nSPARQL that uses nested regular expressions to navigate RDF data. We study some of the fundamental properties of nSPARQL and nested regular expressions concerning expressiveness and complexity of evaluation. Regarding expressiveness, we show that nSPARQL is expressive enough to answer queries considering the semantics of the RDFS vocabulary by directly traversing the input graph. We also show that nesting is necessary in nSPARQL to obtain this last result, and we study the expressiveness of the combination of nested regular expressions and SPARQL operators. Regarding complexity of evaluation, we prove that given an RDF graph G and a nested regular expression E, this problem can be solved in time O(|G||E|).     

知识网格中基于RDF的知识表示技术和应用

简要介绍了两种基本的知识表示技术,以及各自的优缺点;详细介绍了RDF技术,提出了一种基于RDF的知识表示技术及其形式、语法和语义;以数字图书馆信息资源描述的一个实例说明了该技术的实际应用。