Specification,Verification and Prototyping of an Optimized Compiler

This paper generalizes an algebraic method for the design of a correct compiler to tackle specification and verification of an optimized compiler. The main optimization issues of concern here include the use of existing contents of registers where possible and the identification of common expressions. A register table is introduced in the compiling specification predicates to map each register to an expression whose value is held by it. We define different kinds of predicates to specify compilation of programs, expressions and Boolean tests. A set of theorems relating to these predicates, acting as a correct compiling specification, are presented and an example proof within the refinement algebra of the programming language is given. Based on these theorems, a prototype compiler in Prolog is produced.     

Structural Description of Polyaromatic Nucleus in Residue

The proton nuclear magnetic resonance spectroscopy （1H-NMR）, the synchronous fluorescence spectrometry （SFS） and the ruthenium ions catalyzed oxidation （RICO） method were used to determine the chemical structure of polyaromatic nucleus in Oman residue fractions. The results of 1H-NMR analyses showed that the average numbers of aromatic rings in the aromatics, resins and asphaltenes units were 3.2, 5.6 and 8.2, respectively. SFS was used to investigate the distribution of aromatic rings in residue fractions, the main distribution range of aromatic rings in aromatics, resins and asphaltenes were 3 4 rings, 3--5 rings and more than 5 rings, respectively. The aromatic network in residue fractions was oxidized to produce numerous carboxylic acids. The types and content of benzenepolycarboxylic acids, such as phthalic acid, benzenetricarboxylic acids, benzenetetracarboxylic acids, benzenepentacarboxylic acid and benzenehexacarboxylic acid disclosed the condensed types of aromatic nuclei in the core. The biphenyl fraction （BIPH）, the cata-condensed fraction （CATA）, the peri-condensed fraction （PERI） and the condensed index （BCI） were calculated based on the benzenepolycarboxylic acids formed. The results implied that there was less biphenyl type structures in all residue fractions. The aromatics fraction was almost composed of the cata-condensed type system, and the asphaltenes fraction was wholly composed of the peri-condensed type system, while in the resins fraction co-existed the two types, herein the peri-con- densed type was predominant over the cata-condensed type. Based on the analytical results obtained in the study, the components --aromatics, resins and asphaltenes -- were given the likely structural models.     

星间激光通信技术进展与趋势

较详细地评述了目前国外卫星间光通信技术研究的现状．根据关键单元技术的进展情况，总结了未来星间光通信系统的发展趋势。     

安钢高线粗中轧机导卫设计特点

介绍了安钢自行设计的高线粗中轧机导卫装置的设计原则和特点。     

Do different reputation systems provide consistent signals of seller quality: a canonical correlation investigation of Chinese C2C marketplaces

In recent years, consumer-to-consumer (C2C) marketplaces such as eBay and Taobao have adopted a component rating system, and run it simultaneously with but independent of a binary rating system. This paper investigates the extent to which binary rating and component rating systems are able to provide consistent signals of sellers?? quality, focusing on the reputation system design under the Chinese context. Using field data from Taobao, we performed canonical correlation analyses and found that the reputation signals of the two systems are generally correlated. As expected, negative and neutral ratings accurately reveal buyer dissatisfaction. Our results, however, show that positive ratings exhibit negative correlations with the three component ratings (i.e., item-as-described, customer service, and on-time delivery), suggesting that large numbers of positive ratings on Taobao may encourage trust in the platform but do not help to choose credible sellers. Our results elucidate the role of cultural difference in explaining the negative relationship in China and provide important implications for the design of reputation systems.     

基于电力大数据的配电网健康管理方法

配电网的安全稳定运行,对提升供电可靠性、保障用户电能质量、提高电网企业综合效益具有十分重要的意义.以杭州市萧山区为例,介绍基于电力大数据的配电网健康管理方法.     

2000年以来黄河宁蒙河段开河期冰凌洪水特点分析

黄河宁蒙河段开河期冰凌洪水主要集中在3月中下旬,一般由融冰洪水与冰坝洪水组成,其特点主要表现在:凌峰、洪量年际变化大,沿程增加明显,头道拐站易形成多峰,峰型系数较夏汛小,洪水历时较夏汛短,水位表现较夏汛同流量水位高,流速在涨水段慢于落水段。这些特点主要与宁蒙河道形态、水利工程、封河期上游来水及开河期气温、开河形势、封冻期形成的槽蓄水增量大小、沿程分布及其释放程度有关。     

浅谈铜头电站2F机组调速器抽动原因与处理

在分析铜头电站2F机组调速器抽动的基础上,介绍了故障的过程及处理,探讨了产生的原因,逐个进行了检查排除和有针对性的处理,消除了调速器抽动现象。     

文本图像信息的提取与识别

文本是计算机视觉的许多应用中的一项重要特征,图像中的文本往往包含着比较丰富的信息,将文本图像信息里的文字进行提取和识别,对于图像内容的分析、理解、信息检索等方面具有重要的意义。文本图像的识别分为预处理,文字的切分,细化,特征选择与提取,最后对候选文字进行识别。在文字的切分方面提出了一种改进的投影算法,该算法能在很大程度上提高文字切分的准确度,采用基于数学形态学算法对文字进行细化处理,并在特征选择方面引用了多级分类的算法。     

Algebraic approach to linking the semantics of web services

Web services have become more and more important in these years, and BPEL4WS (BPEL) is a de facto standard for the web service composition and orchestration. It contains several distinct features, including the scope-based compensation and fault handling mechanism. We have considered the operational semantics and denotational semantics for BPEL, where a set of algebraic laws can be achieved via these two models, respectively. In this paper, we consider the inverse work, deriving the operational semantics and denotational semantics from algebraic semantics for BPEL. In our model, we introduce four types of typical programs, by which every program can be expressed as the summation of these four types. Based on the algebraic semantics, the strategy for deriving the operational semantics is provided and a transition system is derived by strict proof. This can be considered as the soundness exploration for the operational semantics based on the algebraic semantics. Further, the equivalence between the derivation strategy and the derived transition system is explored, which can be considered as the completeness of the operational semantics. Finally, the derivation of the denotational semantics from algebraic semantics is explored, which can support to reason about more program properties easily.