受限域FAQ中文问答系统研究

在受限域中采用常问问题(FAQ)实现业务咨询系统是一种较好的问答模式,提出了一种受限域FAQ问答系统模型,借助于本体论的思想,构建了领域知识库,利用KDML语言定义和描述了领域本体及本体之间的关系,并实现了领域知识库"领域知网"与常识库"知网"的融合.在此基础上,提出了一种问句相似度的计算方法,该方法借助领域问句所具有的特点,结合问句中的词法关系、句法依存关系及领域概念关系,实现问句相似度计算.并以相似度计算为基础,从侯选问题集中检索相关问句,提取问题答案.云南旅游FAQ问答原型系统测试结果表明该方法可行,有较好的效果.     

Daonity – Grid security from two levels of virtualization

The service oriented architecture of grid computing has been thoughtfully engineered to achieve a service level virtualization: not only should a grid be a virtual machine (also known as a virtual organization, VO) of unbounded computational power and storage capacity, but also should the virtual machine be serviceable in all circumstances independent from serviceability of any of its component. At present, a grid VO as a result of service level virtualization only is more or less confined to participants from scientific computing communities, i.e., can have a limited scale. It is widely agreed that for a grid to pool resources of truly unbounded scale, commercial enterprises and in particular server-abundant financial institutions, should also “go for the grid,” i.e., open up their servers for being used by grid VO constructions. We believed that it is today's inadequate strength of the grid security practice that is the major hurdle to prevent commercial organizations from serving and participating the grid.This article presents the work of Daonity which is our attempt to strengthening grid security. We identify that a security service which we name behavior conformity be desirable for grid computing. Behavior conformity for grid computing is an assurance that ad hoc related principals (users, platforms or instruments) forming a grid VO must each act in conformity with the rules for the VO constitution. We apply trusted computing technologies to achieve two levels of virtualization: resource virtualization and platform virtualization. The former is about behavior conformity in a grid VO and the latter, that in an operating system. With these two levels of virtualization working together it is possible to build a grid of truly unbounded scale by VO including servers from commercial organizations.     

无线传感器网络S-MAC协议的分析与改进

无线传感器网络是一项新兴的技术,能广泛应用于环境监测、智能空间、医疗系统和机器人开发等领域,媒体接入控制协议(MAC)是保证该网络高效运行的关键协议之一.分析一种经典的MAC协议:S-MAC协议,对该协议存在的问题进行了探讨并提出一些改进的措施.     

镨改性铈锆氧化物固溶体的制备与表征

采用溶胶-凝胶法制备了不同比例的Pr掺杂铈锆氧化物固溶体Ce0.6Zr0.4-xPrxO2-y(x=0.05, 0.10, 0.15).X射线衍射证实形成的固溶体为萤石型立方相结构;BET比表面积分析表明,随着Pr的掺杂量由x=0.05递增到x=0.15,在650℃焙烧的样品其比表面积由66.5m2·g-1增加到79.9m2·g-1,而未掺杂样品Ce0.6Zr0.4O2的比表面积为65.1 m2·g-1;粒度分布及透射电镜分析发现,制备的固溶体在水相中存在着团聚现象.应用在含有Pt, Rh和Pd的三效催化剂的制备.催化活性测试表明,在铈锆氧化物储氧材料中掺杂少量Pr,可降低三效催化剂对CO、C3H6和NO的起燃温度.不论是在富燃区还是在贫燃区,所有掺杂Pr的三效催化剂对各气体的催化转化率均高于未掺杂Pr的三效催化剂.     

磁浮列车用铜基受电靴滑块材料的研究

研究了一种新型Cu-Sn-Pb-Cr-C受电靴滑块材料,并进行了性能测定和组织观察.结果表明:受电靴滑块材料具有优良的综合性能,其抗拉强度为138.1MPa,断口局部范围内有韧断特征;摩擦系数为0.38,其摩擦性能大大优于纯Cu;材料的电导率可达74%IACS,明显高于纯Al(60%IACS).从其微观结构可以发现,试样材料中Cu基体以连续网状形式分布,加入的石墨比较均匀地分布在网络空隙内,充分发挥了材料的导电性能及石墨的自润滑性能.     

近地空间强流脉冲中子源大气传输散射γ特性研究

基于射线与物质的相互作用原理和辐射输运理论，建立了近地空间强流脉冲中子源在大气中输运时与气体散射产生γ射线传输到同步轨道的数学物理模型，应用MCNP程序对散射γ输运至地球同步轨道的特征参数进行了数值模拟，获得了一些规律性的辐射现象，并依据这些辐射特征，初步提出了散射γ探测器相关指标，为相关研究提供了一定参考。     

一种星上资源动态分配的GSM网络扩展方案

在农村和偏远地区实现地面蜂窝网的覆盖成本高、代价大。iDirect Technologies提出通过卫星基于TDMA体制实现GSM网络的扩展,可以大大节省星上的带宽资源,为电信运营商对地面蜂窝网络的扩展提供了新的增长点。     

机械合金化FeCo微波吸收材料的研究

开展了FeCo微波吸收材料的研制及其微观结构、磁性能和微波吸收特性的研究，主要是采用机械合金化的方法制备纳米晶Feco固溶体合金粉末，通过电磁参数的调整和改变提高吸收剂的微波吸收性能。研究表明：采用机械合金化制备的Feco合金粉末与常规羰基铁粉相比，饱和磁感应强度提高10％，磁导率和介电常数在一定频率范围大幅度提高；机械合金化制备的Feco合金粉末作为吸波材料的吸收剂，与常规羰基铁粉相比，在质量分数相同的情况下，微波反射率峰值频率向低端移动；FeCo合金型吸波材料在厚度一定的条件下，微波反射率峰值频率随FeCo吸收剂质量分数的提高而降低。     

Synthesis and Crystal Structure of A Bimetallic Terbium Complex Tb2 {μ-CH2 SiMe2 NC6 H3 ^iPr2 -2, 6}3 （THF）3

The reaction of 2, 6-^iPr2CbH3NHSiMe3 with Tb（CH2SiMe3）3（THF）2 in benzene at room temperature afforded a binuclear terbium complex Tb2 {μ-CH2 SiMe2 NC6 H3 ^iPr2 -2, 6}3（THF）3. X-ray diffraction revealed that Tb atoms were bridged by three methylene units. One Tb atom was six-coordinated by two nitrogen atoms, three methylene carbons, and one THF molecule, while the other Tb atom was six-coordinated by one nitrogen atom, three methylene carbons, and two THF molecules. Both Tb atoms adopted a distorted trigonal prism geometry.     

Ti微合金化高强耐候钢的成分设计研究

基于珠钢EAF-LF-CSP流程，以集装箱板的成分为基础，研究了Ti的加入范围，设计出高强耐候钢中的化学成分，开发出屈服强度为450-700MPa的高强钢。