聚烯烃高效载体催化剂的研究

本文以MgCl2、SiO2为载体,研制了多种配方的Ziegler-Natta钛系高效最体催化剂.在实验过程中改变MgCl2、SiO2、甲基硅油等加入量,改变反应时间、反应温度,并对催化剂组成进行了化学分析.在分析敷据的基础上进行乙烯及丙烯的聚合实验,对产品进行性能分析,确定原料加入量、反应时间、反应温度等对催化剂效率、产品性能的影响.     

水泥磨电机的振动测试与故障诊断

采用振动测试的方法,通过对传动系统振动信号的时域、频域和幅值域分析,实现了对水泥磨电机的故障诊断。该方法对其它同类大型旋转机械的故障诊断具有参考价值。     

Synthesis and characterization of molybdenum disulfide micro-sized solid spheres

Mono-dispersed molybdenum disulfide solid spheres with the diameter of 0.5–2 μm have been successfully synthesized by a solvothermal method with a homemade quaternary ammonium salt of 2-undecyl-1-dithioureido-ethyl-imidazoline (SUDEI) as surfactant. The obtained solid spheres are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS), respectively. The influences of reaction conditions are discussed while a mechanism is proposed to explain the formation of the peculiar morphology.     

Hemocompatibility of lanthanum oxide films fabricated by dual plasma deposition

Lanthanum oxide films were fabricated using dual plasma deposition. X-ray photoelectron spectroscopy (XPS) showed that La existed in the + 3 oxidation state. X-ray diffraction (XRD) revealed a (101) oriented hexagonal structure. Blood platelet adhesion tests and endothelial cell cultures were used to evaluate the hemocompatibility of the as-deposited films. Scanning electron microscopy (SEM) and optical microscopy were employed to evaluate the surface morphology of the blood platelets and endothelial cells on the films. The results showed that the number of adhered, aggregated and morphologically changed platelets was reduced compared to that observed on low-temperature isotropic carbon (LTIC). Endothelial cells culture tests indicated good adhesion and proliferation of human umbilical vein endothelial (HUVE) cells in vitro. Our study suggests that lanthanum oxide films are potential blood-contacting biomedical materials.     

Solid-state interfacial reactions and compound morphology of cBN grain and surface Ti coating

In order to research thoroughly the mechanism of the solid-state interfacial reactions and the induced compound morphology of cubic boron nitride (cBN) abrasive grains and the surface Ti-coating layer, annealing experiments of Ti-coated cBN grains were conducted at different temperatures of 550-950 °C for dwell times of 60 min under high-vacuum conditions. The corresponding interfacial characteristics were investigated by differential thermal analysis, X-ray diffraction and scanning electron microscopy. The results show that the relevant interfacial reactions and compound morphology between cBN and Ti are significantly influenced by the heat-treatment temperature. No reaction occurs below 550 °C, and TiN is the sole reaction product during heating from 650-750 °C. Three kinds of compounds, TiN, TiB₂ and TiB, can exist in the interfacial region at 950 °C. Here, the favorable interfacial structures, cBN/TiB₂/TiB/(TiB+TiN)/TiN/Ti, are developed for the excellent mechanical and chemical transition effects between cBN grains and Ti coating. The thermodynamic analysis finally predicts that there is a reasonable probability for the formation of such a special interfacial transition layer.     

802.11b无线网络环境下视频会议系统的流量特性研究

本文通过对MPEG4IP软件包的修改,测量了802.11b与802.3混和网络环境下视频会议系统的分组流量特性,包括不同视频码率和不同网络结构的组合.并与计算机系统和网络性能评价中常用的负指数分布假设的流量特性进行了比较,表明使用负指数分布与泊松到达模型对于描述无线网络环境下的视频会议系统存在很多不足.本文的测量结果对于设计WLAN环境下视频会议系统具有重要的参考价值.     

基于叠加定理的流动追踪问题

在比较分析现有潮流追踪方法的基础上,提出基于叠加定理的电流追踪方法。该方法对电源电流进行追踪,利用电流叠加定理确定电源在支路的电流分量并建立数学模型,可将网络中任意一点功率追踪到电源,并给出支路损耗及支路潮流对电源的分摊原则。以算例验证该方法的有效性,对潮流追踪问题的解决提供了一条新思路。     

110 kV变电站电气主接线及配电装置型式变化与发展

对某地区110 kV变电站电气主接线及配电装置型式在过去十多年里的变化与发展情况进行分析,对由此而带来的变电站一、二次设备的简化与发展情况也进行了探讨。     

山区公路工程建设期水土流失量的预测模式

山区公路工程由于线长、工程量大,施工期可能引起比较严重的水土流失。在编制公路工程水土保持方案时,需要对水土流失量进行预测。公路沿线原地貌水土流失量及新增水土流失量之和即为全部的水土流失量。公路沿线原地貌水土流失量可以采用平均侵蚀模数法及通用土壤流失方程式进行预测,新增水土流失量由扰动地表和工程弃堆渣引起的水土流失量组成。最后,通过具体的工程,对山区公路工程建建设期水土流失量的预测模式进行了实证。