不改变数据位置的排序算法及动态演示

实际应用中经常遇到要求不改变原始数据的顺序而按关键字的大小对数据进行排序的情况,原有的一些经典排序算法不能直接用于解决该类问题。经过对选择排序算法进行研究,给出基于选择思想的不改变数据位置而对数据进行排序的算法,并利用C#语言编程对该算法的实现过程进行动态演示。     

A novel keyword search paradigm in relational databases: Object summaries

This paper introduces a novel keyword search paradigm in relational databases, where the result of a search is an Object Summary (OS). An OS summarizes all data held about a particular Data Subject (DS) in a database. More precisely, it is a tree with a tuple containing the keyword(s) as a root and neighboring tuples as children. In contrast to traditional relational keyword search, an OS comprises a more complete and therefore semantically meaningful set of information about the enquired DS.The proposed paradigm introduces the concept of Affinity in order to automatically generate OSs. More precisely, it investigates and quantifies the Affinity of relations (i.e. Affinity) and their attributes (i.e. Attribute Affinity) in order to decide which tuples and attributes to include in the OS. Experimental evaluation on the TPC-H and Northwind databases verifies the searching quality of the proposed paradigm on both large and small databases; precision, recall, f-score, CPU and space measures are presented.     

XML关键字检索的访问控制规则和索引

XML数据库的关键字检索简单易用,并且用户不必了解数据库的模式,近期受到人们的广泛关注。当前的相关研究主要集中于关键字检索的算法以及返回结果的组织和排序,然而却忽视了关键字的安全访问控制问题。结合XML关键字搜索和XML安全访问控制,提出一种新的建立于XML Schema上基于角色的访问控制规则SRACP(Schema Role Access Control Policy),并在SRACP规则的基础上建立安全的XML关键字检索的索引(SRACP-Index),包括:SRACP-Index的数据结构,SRACP-Index的构建和算法,以及如何利用SRACP-Index的建立进行SSLCA的查询。最后通过实验证明该索引和SSLCA查询算法的有效性。     

原油高速流脱盐脱水创新技术

本技术是在重大发明专利成果的基础上进行的研发,为我国海上和陆上原油脱水和脱盐生产提供新一代自动化集成设备的技术,系统采用先进的多相态液膜分离技术,使得进液流场与脉冲电场在快速顺序流动分离过程中达到最佳结合,大大的提高了处理量,满足企业对原油深度脱盐的要求。     

反垃圾邮件前沿技术分析及未来展望

该文通过分析垃圾邮件的社会背景和现状,对现有的各种反垃圾邮件技术的优缺点进行分析及评估,并提出该行业技术的发展方向和展望。     

A numerical analysis of cooling water temperature of two-stage adsorption chiller along with different mass ratios

This paper deals with the performance investigation of a silica gel/water based on two-stage, four-bed adsorption chiller with different mass allocation between upper and lower beds employing the re-heat scheme. The innovative chiller is powered by waste heat or renewable energy source of temperature between 50 °C and 90 °C with a coolant of inlet temperature 30 °C for air conditioning purpose. The performance of the four-bed adsorption chiller employing the re-heat scheme is compared with that of the two-stage conventional chiller with the re-heat scheme using equal mass allocation. Results show that cooling capacity can be improved with the optimum allocation of adsorbent mass to the upper beds than that of lower beds. Besides, it is observed that the cooling capacity can be improved up to 10.78% while the cooling water temperature is at 20 °C.     

钢球水基精研润滑剂

介绍国内外钢球水基精研润滑剂的现状和发展 ,对钢球水基精研润滑剂的分类、成分和工作性能做了详细的阐述 ,阐明其优点和不足之处 ,并指出了水基精研技术的发展方向。附图 2幅。     

Interfacial Reaction between Zn-Al-Based High-Temperature Solders and Ni Substrate

The Zn-Al(-Cu) eutectic alloys (melting point 381°C) are candidates for use as Pb-free high-temperature solders as a substitute for Pb-based solders, which are suitable for severe working environments such as the engine room of hybrid vehicles equipped with an inverter system as well as a heat engine. In this study, the interfacial reaction between Zn-Al(-Cu) alloys and the Ni substrate during soldering, aging, and thermal cycling was investigated. Semiconductor chips and Ni substrates were soldered with Zn-Al(-Cu) alloys at various temperatures under a nitrogen atmosphere. The soldered assemblies were then heat-treated at 200°C and 300°C to examine the microstructural evolution at the soldered interface. The effect of severe thermal cycles between −40°C and 250°C in air on the microstructure and fracture behavior at the solder joint was investigated. Even after a 1000-cycle test, the thickness of the Al₃Ni₂ layer formed at the interface between the Zn-Al-based solder and the Ni substrate, which is responsible for the damage of the soldered assemblies, was quite small.     

Rigorous Analysis of Wide-Band Directional Coupler Using Π-Shape Dielectric Waveguide

Wide-band directional couplers using П-Shape dielectric waveguide in the parallel coupling region are investigated in detail by a rigorous mode matching method, both the eigenvalue problem of the coupled П-guide and the coupling characteristics of curved transition structure are solved accurately. Particular attention is directed toward the effects of transition waveguides on the scattering and coupling performance of the coupler to give useful guidelines for the design and optimization consideration. Finally, a 3-dB directional coupler is proposed with quite constant coupling factor (within ±0.5dB) throughout a wide frequency band from 34 GHz to 40 GHz.     

Experimental Investigation and Thermodynamic Description of the Constitution of the Ternary System Cr-Si-C

The constitution of the ternary system Cr-Si-C is investigated using differential thermal analysis and X-ray diffractometry techniques. Eight invariant reaction temperatures involving the liquid phase are determined. The crystal structures and phase partitions observed for the subsolidus temperature region confirm literature data. Thermodynamic modeling, using a minimum of adjustable ternary parameters and assuming the binary high-temperature phase, β-Cr₅Si₃, to be stabilized toward lower temperatures as ternary D 8₈-type Cr₅Si₃C _x , generally reproduces the measured temperatures within 10 K. The calculated liquidus surface contains four ternary eutectics, three transition reactions, three degenerated reactions, and five (pseudobinary eutectics) maxima. The reaction scheme shows that no solid-phase reactions occur in the Cr-Si-C system at >1000°C, except for the binary transition β-Cr₅Si₃↔α-Cr₅Si₃. The activity diagram along the section Cr-SiC at 1300°C, computed from the optimized data set, agrees with the observed diffusion path.