FeBP非晶态合金超细微粒的合成及其对PH3分解的催化作用

用化学还原法合成了FeBP非晶态合金超细微粒，用电感耦合等离子体光谱（ICP）、X射线粉末衍射（XRD）、透射电子显微镜（TEM）和差热分析（DSC）等手段对其进行了物性表征，并用微型催化反应装置考察了其对PH3分解的催化作用，结果表明，非晶态合金FeBP对PH3的分解具有良好的催化作用，能使PH3的分解温度从800℃以上降到500℃左右。490℃时分解率超过90％，540℃时达100％。     

软交换技术的发展及其应用

软交换是下一代网络NGN的核心技术，本文从软交换的概念入手，介绍了软交换的基本功能及其优点．软交换的网络系统结构、软交换的对外接口等内容，并探讨了软交换技术的应用。     

A new colloidal precursor cooperative conversion route to nanocrystalline quaternary copper sulfide

A novel milk-like Cu-thiourea colloid has been synthesized. Nanocrystalline quaternary copper sulfide Cu₂FeSnS₄ was obtained through the Cu-thiourea colloidal precursor cooperative conversion route at low temperature. The samples were characterized by means of X-ray powder diffraction, transmission electron microscopy, scanning electron microscopy, inductively coupled plasma atomic emission spectroscopy, and X-ray energy dispersive spectroscopy techniques. The reaction details and features were described and discussed.     

水电站复杂输水系统恒定流的数值计算

对单元总体方程进行了局部修改，使方程的求解具有唯一性和更高的可靠性。提出水电站恒定流数值计算只有四种给定条件，每种条件都能保证计算结果的唯一性；计算实例证明，相同工况条件下根据四种给定条件求解的计算结果非常吻合。     

冲击噪声背景下的近场源二维参数估计方法

本文针对背景噪声为冲击噪声的情况,提出了一种新的近场源二维参数估计方法.本方法利用协变异(或协变异系数)构造矩阵,并通过求根的方法估计近场源的方向角和距离参数.该算法可以抑制冲击噪声对估计性能的影响,同时具有无需谱峰搜索的优点.仿真实验证明了该算法的有效性.     

A new distributed approximation algorithm for constructing minimum connected dominating set in wireless ad hoc networks

In recent years, constructing a virtual backbone by nodes in a connected dominating set (CDS) has been proposed to improve the performance of ad hoc wireless networks. In general, a dominating set satisfies that every vertex in the graph is either in the set or adjacent to a vertex in the set. A CDS is a dominating set that also induces a connected sub‐graph. However, finding the minimum connected dominating set (MCDS) is a well‐known NP‐hard problem in graph theory. Approximation algorithms for MCDS have been proposed in the literature. Most of these algorithms suffer from a poor approximation ratio, and from high time complexity and message complexity. In this paper, we present a new distributed approximation algorithm that constructs a MCDS for wireless ad hoc networks based on a maximal independent set (MIS). Our algorithm, which is fully localized, has a constant approximation ratio, and O(n) time and O(n) message complexity. In this algorithm, each node only requires the knowledge of its one‐hop neighbours and there is only one shortest path connecting two dominators that are at most three hops away. We not only give theoretical performance analysis for our algorithm, but also conduct extensive simulation to compare our algorithm with other algorithms in the literature. Simulation results and theoretical analysis show that our algorithm has better efficiency and performance than others. Copyright © 2005 John Wiley & Sons, Ltd.     

Effects of surfactant/silica and silica/cerium ratios on the characteristics of mesoporous Ce-MCM-41

Using the surfactant CTMABr (cetyltrimethyl ammonium bromide) and cerium(IV) sulfate, mesoporous Ce-MCM-41 molecular sieves were produced under a hydrothermal condition with various surfactant/silica (surfactant/Si) and silica/cerium (Si/Ce) ratios. Changes to the structural traits caused by changing the molar ratios of both surfactant/Si and Si/Ce were investigated. XRD (X-ray diffraction), FT-IR (fourier transform infrared spectroscopy), and SEM (scanning electro microscopy) were used for the characterization of prepared mesoporous samples. Among the tested molar ratios, surfactant/Si ratio of 0.5 and 0.2 showed highest values of d_1 0 0 and intensity, respectively, for the Si-MCM-41. XRD analysis also identified a quintessential hexagonal structure of Ce-MCM-41 for the Si/Ce molar ratio higher than 40 (maintaining the surfactant/Si ratio at 0.2). When cerium content was increased to have the Si/Ce molar ratio of 20, the hexagonal structure of Ce-MCM-41 was collapsed due to the structural stress of substituted cerium. FT-IR results confirmed calcination of Ce-MCM-41 and the incorporation of Ce⁴⁺ ions of cerium sulfate into the silica surface with proper removal of the surfactant. Rod-like shape with rounded edges of the prepared Ce-MCM-41 samples was identified by SEM. These results suggest surfactant/Si ratio of 0.2 and Si/Ce ratio of 40 for the production of Ce-MCM-41 with the highest level of crystallinity.     

市区微蜂窝传播路径损耗模式的比较检验

讨论了几种微蜂窝路径损耗模式,并用我国某城市测量的微蜂窝传播数据对COST231WI,修正COST231WI和Xia模式进行了检验,结果表明修正COST231模式的误差最小,Xia模式次之,COST231WI模式最差。从而得到修正COST231模式比较符合我国实际的微蜂窝传播预测模式。     

智能电动机控制器在电收尘通风机上的应用

对智能电动机控制器的情况作了介绍，结合工作实践提出了维护要点和建议，并对该控制器的参数设置进行了说明，这对使用该设备的工业企业有一定的指导意义。