Effect of Counterions on Synthesis of Mesoporous Silica by the Route of Template

Mesoporous silica materials with ordered hexagonal and parallel-arranged pore channel have been synthesized using cetyl trimethylammonium bromide as a template and Na₂SO₄ as counterions. Their ordered mesostructures were characterized by infrared spectroscopy, X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy, and nitrogen sorption analysis. The effects of Na₂SO₄ concentration on variations of morphology, specific surface area, and pore size were discussed; the results show that a high concentration of Na₂SO₄ induces the formation of crystal threads with a "tubules-within-tubule" structure, and also leads to mesoporous silica materials with spherical, fabaceous, sheet-like, or prismatic shapes. The results also show that a high concentration of Na₂SO₄ can make the pore size decrease, but cannot change pore wall thickness, demonstrating the stability of the hexagonal-shaped pores.     

Ultrasonic oscillations effect on rheological and processing properties of metallocene‐catalyzed linear low density polyethylene

The effects of ultrasonic oscillations and die materials on die pressure, productivity of extrusion, melt viscosity of metallocene‐catalyzed linear low density polyethylene (mLLDPE), as well as their mechanism were studied in a special ultrasonic oscillations extrusion system developed in our lab. Die materials used in our experiment included steel, brass, and polytetrafluoroethylene (PTFE)_. The experimental results showed that ultrasonic oscillations as well as die materials have great influence on the rheological and processing behavior of mLLDPE. Ultrasonic oscillations can greatly increase the productivity of mLLDPE melt extruded through different dies, and can decrease the die pressure and the melt viscosity of mLLDPE. Compared with steel or brass die, mLLDPE melt extruded through PTFE die is more sensitive to ultrasonic oscillations. A possible mechanism for the improved processability of mLLDPE is proposed in this article. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1873–1878, 2003     

基于WiFi无线通信的温湿度检测节点设计

基于AM2303温湿度传感器、STC15F104W单片机和WiFi模块设计了一种无线温湿度检测节点。介绍了AM2303及其通信协议、WiFi模块及其组网特性等,并且给出了读取AM2303数据的软件流程。经测试,该节点通信距离远,组网灵活,可很好地应用于粮库粮情检测等实际工作环境。     

石化企业供应链管理研究

介绍了国内外石化行业的供应链管理现状，对中石化电子化供应链方案进行了分析，并就中石化供应链管理存在的问题提出解决方案。     

保证云存储的数据安全

近几年来,云存储的使用越来越广泛,不仅是中小型企业,而且针对个体用户也可以购买云存储服务,但如何在云存储中保证数据的安全性和机密性,单靠云存储服务供应商的承诺是难以让人信服的。本文提出了一种保证数据安全的云存储框架,并且使用服务等级协议（SLA）作为用户和供应商之间的共同标准。此外,本文还提及了几种保证云存储数据安全的技术,这些技术可以被分成三类：存储保护,传输保护和授权保护。     

基于商业智能的小区日用水量预测模型研究

商业智能现在已广泛应用于各个领域,利用商业智能可以对趋势预测做出良好的支持,本文将其中一种常用商业智能的工具——数据仓库技术,应用于小区家庭的用水量预测研究。     

网络安全管理平台研究

信息网络的迅速发展普及应用,在给人们的工作、生活带来巨大便利的同时,也带来了许多安全隐患,出于政治、经济、文化等利益的需要或者好奇心的驱动,网络攻击事件层出不穷、屡见不鲜,且有愈演愈烈之势,轻者给个人或机构带来信息损害、经济利益损失,重者将会影响国家的政治、经济和文化安全.因此,信息网络安全问题已成为国内外研究重点.     

基于开放源代码的防火墙实验项目设计

当前计算机网络安全课程已经广泛地开设于计算机及信息安全等相关专业,而防火墙技术又是计算机网络安全课程的重要内容之一。用专用硬件防火墙作为实验设备具有价格昂贵、内部技术不透明的缺点,因此本文设计一系列基于Linux操作系统开放源代码的防火墙技术实验,这样不仅可以降低教学实验成本,也能让学生更清楚地了解各种防火墙技术及实现,增强学生的专业实践能力。