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.

基于消息中间件的分布式查询系统

在三层结构中,中间层的实现是整个系统的核心.提出了一个基于消息中间件实现中间层的结构框架,能够以较少的花费实现一个分布式查询系统.中间层各个业务组件利用消息中间件通信,屏蔽了网络复杂性,实现异构平台的互操作,利用持久队列可以确保通信的可靠性,减轻了系统的开发工作和复杂度.

基于本体的异构信息集成查询划分及转换

使用本体赋予信息语义能够帮助用户准确查询所需要的信息.基于本体的异构信息集成中的关键问题是如何实现全局本体概念实例查询到局域信息数据查询的变换.提出了一种本体概念实例查询的操作表示,并基于这一查询操作表示给出了将全局查询划分为局域查询的方法,局域查询结果经过集成和转换后以统一的形式返回给用户.使用该方法来查询所集成的数据来源,可以获取用户所需要的正确查询结果.

两类模糊PID控制器的等价性分析

变论域与变分布模糊PID控制器是两类不同的自适应模糊控制器 ,分别通过调整转换因子与隶属函数分布对模糊控制器的性能进行调节。利用模糊控制器结构分析方法对这两类模糊PID控制器的本质进行了深入分析。通过分析可以得出结论 ,在一定条件下这两类模糊PID控制器在性能调节方面是等价的。此结论将对这两种模糊PID控制器的应用提供参考

Operational characteristics of a 1.2-MW biomass gasification and power generation plant

In this study, we analyzed the operational characteristics of a 1.2-MW rice husk gasification and power generation plant located in Changxing, Zhejiang province, China. The influences of gasification temperature, equivalence ratio (ER), feeding rate and rice husk water content on the gasification characteristics in a fluidized bed gasifier were investigated. The axial temperature profile in the dense phase of the gasifier showed that inadequate fluidization occurred inside the bed, and that the temperature was closely related to changes in ER and feeding rate. The bed temperature increased linearly with increasing ER when the feeding rate was kept constant, while a higher feeding rate corresponded to a lower bed temperature at fixed ER. The gas heating value decreased with increasing temperature, while the feeding rate had little effect. When the gasification temperature was 700-800C, the gas heating value ranged from 5450-6400kJ/Nm3. The water content of the rice husk had an obvious influence on the operation of the gasifier: increases in water content up to 15% resulted in increasing ER and gas yield, while water contents above 15% caused aberrant temperature fluctuations. The problems in this plant are discussed in the light of operational experience of MW-scale biomass gasification and power generation plants.

Development of a self-thermal insulation miniature combustor

A novel miniature cylindrical combustor, whose chamber wall is made of porous material, has been designed and experimented for reducing heat loss and enhancing flame stability. The combustor has the function of reducing wall heat loss, extending residence time and avoiding radical chemical quenching with a self-thermal insulation concept in which heat loss reduction is obtained by the opposite flow directions between thermal energy transfer and mass flow. The methane/air mixture flames formed in the chamber are blue and tubular in shape. Between the flames and the porous wall, there is a thin unburned film that plays a significant role in reducing the flames' heat loss and keeping the flames stable. The porous wall temperature was 150-400 degrees C when the temperatures of the flames and exhaust gas were more than 1200 degrees C. When the equivalence ratio phi < 1.0, the methane conversion ratio was above 95%; the combustion efficiency was near 90%; and the overall sidewall heat loss was less than 15% in the 1.53 cm(3) chamber. Moreover, its combustion efficiency is stable in a wider combustion load (input power) range.

THE MATRIX ANALYSIS FOR AN OPTICAL FREE-SPACE SWITCHING NETWORK AND AN OPTICAL CROSSOVER NETWORK WITH 4-FUNCTION INTERCHANGE NODES

A matrix analysis for free-space switching networks, such as perfect shuffle-exchange omega, crossover and Banyan is presented. On the basis of matrix analysis, the equivalence of these three switching networks and the route selection between input and output ports are simply explained. Furthermore, an optical crossover switching network, where MQW SEED arrays are used as electrically addressed four-function interchange nodes, is described and the optical crossover interconnection of 64 x 64, and high-speed four-function, interchange nodes is demonstrated in the experiment.

落叶松毛虫防治咨询专家系统

落叶松毛虫是东北林区主要害虫之一，它对松林可以造成毁灭性的破坏，因此，采取及时且必要的综合防治措施，可以带来显著的经济和生态效益。本文依据害虫综合管理的指导思想，采用计算机人工智能程序模型，构建了落叶松毛虫防治咨询专家系统。 落叶松毛虫防治咨询专家系统主要由推理机、知识库、数据库、知识获取机制和用户界面等部分组成。其中知识库和推理机是系统的核心部分。在知识库设计中充分考虑了落叶松毛虫防治的复杂性，结合具体的限定条件，如危害特征、自然环境、地形地貌、害虫的生长阶段等，将知识存储在数据库中形成专家数据库；利用数据库查询语言SQL语句设计了系统的推理机，采用正向推理的方式，增强了知识库的可扩展性和可维护性；知识获取机制面向林业专家，实现知识的获取以及知识库的修改、扩充等任务；数据库用来存放落叶松毛虫的基本信息，用户可以通过数据库来获得落叶松毛虫相应的咨询信息。 落叶松毛虫防治咨询专家系统的目标为：（1）对落叶松毛虫的基本信息、行为特征、生理和生态学特征以及防治方法和施药方法等进行存储和查询。（2）正向推理方式保证专家系统在运行时能方便地选择问题，实现智能推理过程。（3）易用的知识维护。 该系统主要有以下几方面的功能和特点：（1）该系统本着害虫综合管理的指导思想，以落叶松毛虫的种群动态为理论基础，充分考虑不同林地环境条件下的自然控制因素，根据环境、气候和害虫本身的条件推出更加合理的结论，尽量采用生物防治，必要时采用化学防治；（2）系统可向用户提供多种可行的防治方案，经营者可以根据当时当地的实际情况作出决定；（3）系统使用方便；（4）系统具有显示、打印、通过Internet浏览获取信息、显示推理解释等功能。 另外，本文对落叶松毛虫专家系统又进行了有效的评估，评估对象分为三个组别：领域专家、森保人员以及学生。三组人员分别针对系统实用性、友好性、系统提问的简洁程度以及可学习性给出等级分数。通过评估结果，最终认定该系统是可以信赖的。 本系统以落叶松毛虫防治领域专家的经验和知识为基础，有效地将计算机技术和森保专家的知识结合在一起，集落叶松毛虫信息存储浏览、查询、专家系统于一体，对于缓解森林保护专家和人员的不足，提高落叶松毛虫虫害的防治能力，加快科技成果的转化具有重要的意义。

Performance of supersonic model combustors with staged injections of supercritical aviation kerosene

Supersonic model combustors using two-stage injections of supercritical kerosene were experimentally investigated in both Mach 2.5 and 3.0 model combustors with stagnation temperatures of approximately 1,750 K. Supercritical kerosene of approximately 760 K was prepared and injected in the overall equivalence ratio range of 0.5-1.46. Two pairs of integrated injector/flameholder cavity modules in tandem were used to facilitate fuel-air mixing and stable combustion. For single-stage fuel injection at an upstream location, it was found that the boundary layer separation could propagate into the isolator with increasing fuel equivalence ratio due to excessive local heat release, which in turns changed the entry airflow conditions. Moving the fuel injection to a further downstream location could alleviate the problem, while it would result in a decrease in combustion efficiency due to shorter fuel residence time. With two-stage fuel injections the overall combustor performance was shown to be improved and kerosene injections at fuel rich conditions could be reached without the upstream propagation of the boundary layer separation into the isolator. Furthermore, effects of the entry Mach number and pilot hydrogen on combustion performance were also studied.

Study on peak overpressure and flame propagation speed of gas deflagration in the tube with obstacles

The on-way peak overpressure and flame propagation speed of gas deflagration in the tube with obstacles are important data for process safety. Based on carbon monoxide deflagration experiments, the paper presents a multi-zone integration model for calculation of on-way peak overpressure, in which the tube with obstacles is considered as a series of venting explosion enclosures which link each others. The analysis of experimental data indicates that the on-way peak overpressure of gas deflagration can be correlated as an empirical formula with equivalence ratio of carbon monoxide oxidation, expansion ratio, flame path length, etc., and that the on-way peak overpressure exhibits a linear relationship with turbulence factor and flame propagation speed. An empirical formula of flame propagation speed is given.

基于ADO的数据库编程及应用

介绍了如何利用ADO(ActiveX Data Object)接口连接和操作不同的数据库。并给出了在Visual C++.net环境下ADO结合SQL访问数据库的程序代码。

Radiative electron capture and subsequent radiative decay in collisions of U89+ ions with N-2

To evaluate the radiative electron capture for the collisions of U89+ ion with N-2, radiative recombination cross sections and the corresponding emitted photon energies are calculated from the ground state 1s(2)2s to 1s(2)2snl(j) (2 <= n <= 9, 0 <= l <= 6) using the newly developed relativistic radiative recombination program RERR06 based on the multiconfiguration Dirac-Fock method. The x-ray spectra for radiative electron capture in the collision have been obtained by convolving the radiative recombination cross sections and the Compton profile of N2. Good agreement is found between the calculated and experimental spectra. In addition, the transition energy levels and probabilities among the 147 levels from the captured 1s(2)2snl(j) have been calculated. From the calculated results, radiative decay cascade processes followed by the radiative electron capture have also been studied with the help of multistep model and coupled rate equations, respectively. The present results not only make us understand the details of the radiative electron captures and the radiative decay cascade spectra in the experiment but also show a more efficient way to obtain the cascade spectra. Finally, the equivalence between the multistep model and coupled rate equations has been shown under a proper condition and the latter can hopefully be extended to investigate other cascade processes.

HIRFL控制系统数据库系统设计

HIRFL（兰州重离子加速器）是我国第一个大型重离子物理研究装置。HIRFL控制系统是保证HIRFL系统正常高效运转的重要环节。本文利用数据库技术、网络技术设计了HIRFL控制系统数据库系统，实现了在网络环境中只使用一个应用程序就可对整个HIRFL系统控制进行控制的要求。论文首先介绍了数据库系统理论，然后对软件设计涉及的各部分基础知识进行了阐述，最后详细讨论了整个数据库系统设计中的数据库设计、应用程序人机界面设计等部分。数据库应用SQL Server 2000大型数据库，并使用ODBC技术作为数据库访问手段；人机界面部分使用面向对象编程技术进行Windows编程。整个论文工作在建立了一个包含整个控制系统各部分设备信息的数据库的同时，还提供了一套包含所有基本控制功能的HIRFL分布式控制软件，为HIRPL控制系统数据库系统的进一步完善提供了二次开发平台。