Scenario-based knowledge representation in case-based reasoning systems

A scenario-based representation model for cases in the domain of managerial decision-making is proposed. The scenarios in narrative texts are converted to scenario units of knowledge organization. The elements and structure of the scenario unit are defined. The scenario units can be linked together or coupled with others. Compared with traditional case representation methods based on database tables or frames, the proposed model is able to represent knowledge in the domain of managerial decision-making at a much deeper level and provide much more support for case-based systems employed in business decision-making.     

烟气脱硫技术的开发动向

着重介绍发达国家在湿式烟气脱硫系统中采用的几项新技术和新开发的几种干式烟气脱硫技术。     

Refinement of packet size in low carbon bainitic steel by special thermo-mechanical control process

The packet size of bainitic steel can be refined by a special relaxation-precipitation-control phase transformation (RPC) technology, When processed by RPC process, the low carbon bainitic steel composes of two kinds of main intermediate transformation phases. One is ultra-fine lath-like bainitic ferrite and the lath is less than 1 tam in width and about 6 tam in length; the alignment of laths forms a refined packet, and the size of packets is about 5-7 ~am in length and about 3-4 tam in width, The other is acicular structure. The morphology and distribution of these acicular structures are influenced by relaxation process, the thin and short acicular structures cut the prior austenite grain and refine the bainitic packet size, For the optimum relaxation time, the packet size can be refined to the finest. The mechanical properties are influenced by relaxation time and the 800 MPa grade low carbon bainitic steel with excellent toughness can be obtained by RPC process,     

Field Emission Properties of Nano-DLC Films Prepared on Cu Substrates by Pulsed Laser Deposition

Nano-diamond like carbon (DLC) thin films were prepared on fused silica and Cu substrates by the pulsed-laser deposition technique with different laser intensities. Step-measurement, atomic force microscope (AFM), UV-VIS-NIR transmittance spectroscopy and Raman spectroscopy were used to characterize the films. It was shown that the deposition rate increases with the laser intensity, and the films prepared under different laser intensities show different transparency. Raman measurement showed that the content of sp³ of the Nano-DLC thin films decreases with the laser intensity. The field emission properties of the Nano-DLC thin films on Cu substrates were studied by the conventional diode method, which showed that the turn-on field increases and the current density decreases with sp³ content in the films. A lower turn-on field of 6 V/um and a higher current density of 1 uA/cm² were obtained for Nano-DLC thin films on Cu substrate.     

Thermal expansion anomaly and spontaneous magnetostriction of Gd2Fe17 compound

Materials with negative thermal expansion have many practical applications. However, these materials are known in only several oxide systems, and when the negative thermal expansion occurs, the contraction is usually small and limited to a narrow temperature range beyond room temperature. For obtaining a compound with negative thermal expansion in broad temperature range, the structural and magnetic properties of Gd2Fe17 compound were investigated by means of X-ray diffraction and magnetization measurements. The Gd2Fe17 compound annealed at 1050 oC had a Th2Zn17-type structure. There existed an anisotropic strong spontaneous magnetostriction and a negative thermal expansion in Gd2Fe17 compound. The average thermal expansion coefficients was =-7.40×10-6/K in the temperature range of 294-453 K and =-1.80×10-5/K in 453-534 K, respectively. The spontaneous magnetostrictive deformation ωS decreased from 4.34×10-3 to near zero with temperature increasing from 294 to 572 K. The spontaneous linear deformation λc was much larger than λa at the same temperature below about 500 K.     

基于CURE的用户聚类算法研究

通过对Web网站的日志进行聚类分析,目的是获取用户兴趣访问模式,进而为不同用户群体提供定制的个性化服务。针对原始CURE算法在代表点选择的随机性、不能充分体现用户兴趣偏好方面存在的问题,提出了改进的用户聚类算法,根据用户兴趣的显著特征提取元素的主要属性进行预聚类,为小类合并提供合理的初始类集,实验结果证明了该方法有较好的聚类结果。     

程控形变的血管组织工程支架进展

心血管疾病是当前人类生命健康的首要威胁。血管组织工程支架可用于病变血管的再生修复,为心血管疾病治疗提供了选择。然而,现有血管组织工程支架尚面临界面适配的挑战,导致植入后易发生并发症而难以被临床转化。最近研发的具有程控形变能力的血管组织工程支架不但可动态适应不同尺寸的血管三维形态,而且可有序引导血管细胞的行为功能,为解决血管组织工程支架界面适配难题提供了机遇。作者对程控形变血管组织工程支架的最新研究进展和现存挑战进行综述和展望,有望为新一代组织工程血管支架的研发和转化提供启示。     

精馏塔的H∞优化控制仿真

该文基于H∞控制理论对精馏塔设计了优化控制器,并进行了闭环仿真实验。仿真结果表明：当系统存在干扰时,H∞控制器比线性二次型最优调节器（LQR）使精馏塔实际达到的优化性能指标和综合控制指标都要好。     

An efficient processing of a chain join with the minimum communication cost in distributed database systems

This paper investigates the optimization problem when executing a join in a distributed database environment. The minimization of the communication cost for sending data through links has been adopted as an optimization criterion. We explore in this paper the approach of judiciously using join operations as reducers in distributed query processing. In general, this problem is computationally intractable. A restriction of the execution of a join in a pre-defined combinatorial order leads to a possible solution in polynomial time. An algorithm for a chain query computation has been proposed in [21]. The time complexity of the algorithm isO(m ² n ²+m ³ n), wheren is the number of sites in the network, andm is the number of relations (fragments) involved in the join. In this paper, we firstly present a proof of the intuitively well understood fact—that the eigenorder of a chain join will be the best pre-defined combinatorial order to implement the algorithm in [21]. Secondly, we show a sufficient and necessary condition for a chain query with the eigenordering to be a simple query. For the process of the class of simple queries, we show a significant reduction of the time complexity fromO(m ² n ²+m ³ n) toO(mn+m ²). It is encouraging that, in practice, the most frequent queries belong to the category of simple queries. Editor: Peter Apers     

电信综合网管数据模型有效实现方法的研究

针对电信综合网管数据模型实现效率低下问题,本文分别给出其数据模型基于关系数据库、面向对象数据库、对象关系数据库的有效实现方法;并对这三种不同数据库实现的操作性能进行了比较与分析。有关的试验结果表明,电信综合网管数据模型的对象关系数据库实现具有较好的应用效果。