一种基于相似性的文档聚类算法

针对常见信息检索技术的缺陷，提出一种基于相似性的文档聚类分析算法，将文档集合转化为向量集合，基于向量之间的余弦相似度，采取凝聚的层次聚类算法来获得聚类，给出了算法的详细描述的一个测试实例。     

基于H∞鲁棒控制原理的电动助力转向系统研究

针对汽车电动助力转向系统是一个非线性的多输入输出系统的特点，提出了H∞鲁棒控制方法，首先对电动助力转向系统的动力学模型进行不确定性分析，然后建立了状态空间方程和增广被控对象矩阵；在此基础上用H∞方法极小化系统中各种干扰对被控输出的影响，最后通过计算机模拟的结果表明，设计的控制器使闭环系统有好的性能及稳定的鲁棒性。     

Potash-rich volcanic rocks and lamprophyres in western Shandong Province: 40Ar-39Ar dating and source tracing

Highly precise ⁴⁰Ar-³⁹Ar dating results demonstrate that the ages of potash-rich volcanic rocks in western Shandong Province are 114.7–124.3 Ma, and that of the lamprophyres is 119.6 Ma. The potash-rich volcanic rocks have relatively high (⁸⁷Sr÷⁸⁶Sr)_i ratios (0.708715–0.711418) and distinctly negative ε_nd values (−11.47–−17.54), and are enriched in radiogenic lead (²⁰⁶Pb÷²⁰⁴Pb=17.341−17.622, ²⁰⁷Pb÷²⁰⁴Pb=15.525−15.538, ²⁰⁸Pb÷²⁰⁴Pb = 37.563−37.684). Similarly, the lamprophyres also have quite low ε_nd values (−11.57–−19.64). Based on the fact that the Sr, Nd and Pb isotopic compositions of potash-rich volcanic rocks are very consistent with that of the clinopyroxene separates, and by integrating comprehensive analyses of their tectonic settings, and extensive comparisons of the Sr, Nd isotopic compositions with that of the related simultaneous rocks, it is concluded that the potash-rich volcanic rocks and lamprophyres in western Shandong Province were most possibly derived from the partial melting of enriched mantle which was caused by source contamination and metasomatism of subducted continental crustal materials.     

小型园区网络管理系统中计费系统设计与实现

计费管理作为园区网络管理系统的5大功能之一，它能够监测和控制网络操作的费用、代价，记录网络资源的使用情况，分析了几种计费方式，论述了SNMP协议在网络计费系统中的实现，在此基础上设计了一个具体的计费系统模型，该计费系统具有数据采集、数据处理、计费信息查询、计费规则设置和报表生成等功能。     

放大电路中反馈类型判别方法的分析

简述了反馈的概念，各种类型反馈的特征和反馈效果．结合图例较为详细地介绍了反馈类型的判别方法．     

TP77椭圆偏振光测厚仪功能的拓展研究

成功地将TP77椭圆偏振光测厚仪改装成卤钨灯或氙灯为光源的广谱椭偏仪。改装后的椭偏仪不含λ/4波长片，而配有一型号为WDG5001A的单色仪和一个X-Y函数记录仪，它可用来测量固体薄膜和片状材料的折射指数n(λ)和消光指数k(λ)。     

征收生态环境补偿费的理论依据与现实意义

征收生态环境补偿费是一种有效地解决生态环境问题的方法。它不仅为保护和改善生态环境质量提供稳固的资金来源,而且也极大地影响国民经济的发展和人民生活水平的提高。文中就征收生态环境补偿费的理论依据和现实意义作深入剖析。     

Study on variational aerosol fields over Beijing and its adjoining areas derived from Terra-MODIS and ground sunphotometer observation

East Asia is one of areas with larger sulfide emis-sions, and in recent years, more sulfur-rich gases are emitted into the atmosphere along with the rapid growth of economy. A great amount of sulfate aerosol produced in industrial activities not only degrades the environment but also affects the regional climate. In China, besides the sulfate aerosol produced, the dust particle is also one of main aerosols in the atmosphere. According to observa-tions, the soil-origin aerosol still poses the …     

Mixed Model for Silt-Laden Solid-Liquid Two-Phase Flows

The kinetic theory of molecular gases was used to derive the governing equations for dense solid-liquid two-phase flows from a microscopic flow characteristics viewpoint by multiplying the Boltzmann equation for each phase by property parameters and integrating over the velocity space. The particle collision term was derived from microscopic terms by comparison with dilute two-phase flow but with consideration of the collisions between particles for dense two-phase flow conditions and by assuming that the particle-phase velocity distribution obeys the Maxwell equations. Appropriate terms from the dilute two-phase governing equations were combined with the dense particle collision term to develop the governing equations for dense solid-liquid turbulent flows. The SIMPLEC algorithm and a staggered grid system were used to solve the discretized two-phase governing equations with a Reynolds averaged turbulence model. Dense solid-liquid turbulent two-phase flows were simulated for flow in a duct. The simulation results agree well with experimental data.     

氧化铝在熔融冰晶石中的溶解

利用透明石英槽对氧化铝在熔融冰晶石的溶解行为进行了研究,并用摄相机观测、拍摄了整个溶解过程,分析与讨论了氧化铝溶解的影响因素·研究认为,氧化铝在熔融冰晶石中的溶解分两步,即氧化铝快速溶解和电解质表面形成结壳的氧化铝的脱落与溶解·氧化铝在熔融冰晶石中的溶解由快变慢是由于氧化铝的加入导致电解质温度降低,在电解质表面形成氧化铝/电解质结块,使氧化铝与冰晶石接触的表面积下降·氧化铝的溶解速度与搅拌速度、氧化铝的预热温度、体系的温度和氧化铝的种类有关·