自清洁外墙涂料的研究与应用

如何提高外墙涂料的自清洁能力,并使之保持较长的装饰效果一直是涂料界关注的热点。本文综述了微粉化技术、荷叶效应、气球陶瓷理论、自分层技术以及光催化效应的原理,及其在改善外墙涂料自清洁性方面的应用。     

聚丙烯结构壁管专用料的开发

阐述了塑料结构壁管的基本情况和国内外现状．重点就扬子石油化工股份有限公司研究院研制的聚丙烯结构壁管专用料的情况进行了介绍。     

Numerical study of the transfer of shock-wave loading to a screened flat wall through a layer of a powdered medium and a subsequent air gap

The two-velocity, two-temperature model with two stresses in a mixture of a gas and solid particles contacting each other is used to numerically study the dynamic effect of an air shock wave incoming onto a solid wall with a screening layer of a porous powdered medium at some distance from the wall. The process is described for the case of one-dimensional planar motion of the gaseous and disperse phases under the assumption of a viscoelastic behavior of the powder skeleton. The effect of stepwise shock waves onto the porous powdered screen is considered. The influence of parameters of the screening layer and the air gap on the dynamics of loading of the screened solid wall is analyzed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 1, pp. 132–142, January–February, 2007.     

阿尔塔什水利枢纽工程深厚砂砾石覆盖层混凝土防渗墙施工技术研究

阿尔塔什水利枢纽工程是我国在建面板堆石坝工程之一,其深厚的砂砾石覆盖层和庞大的坝体,在施工和运行过程中均会对防渗墙的应力应变产生较大的影响,处理不好直接会影响到大坝整体防渗效果和工程安全。如何在保证施工质量的前提下,优化施工方案,改善防渗墙应力状况,是施工技术研究重点。通过对防渗墙的受力特性、深厚覆盖层的工程特性分析和研究,从防渗墙成墙槽段划分、墙段连接技术、强漏失地层成槽技术和固壁泥浆配比等关键技术上进行优化和改进,有效的消减了防渗墙在坝体填筑和蓄水过程中的应力应变集中,保证防渗墙的成墙质量和运行效果。     

Interfacial in situ polymerization of single wall carbon nanotube/nylon 6,6 nanocomposites

An interfacial polymerization method for nylon 6,6 was adapted to produce nanocomposites with single wall carbon nanotubes (SWNT) via in situ polymerization. SWNT were incorporated in purified, functionalized or surfactant stabilized forms. The functionalization of SWNT was characterized by FTIR, Raman spectroscopy and TGA and the SWNT dispersion was characterized by optical microscopy before and after the in situ polymerization. SWNT functionalization and surfactant stabilization improved the nanotube dispersion in solvents but only functionalized SWNT showed a good dispersion in composites, whereas purified and surfactant stabilized SWNT resulted in poor dispersion and nanotube agglomeration. Weak shear flow induced SWNT flocculation in these nanocomposites. The electrical and mechanical properties of the SWNT/nylon nanocomposites are briefly discussed in terms of SWNT loading, dispersion, length and type of functionalization.     

泄水建筑物下游冲刷坑二维数值模拟

对巨亭水电站泄水建筑物下游局部冲刷过程进行了二维数值模拟。采用RNG k-ε湍流模型封闭N-S方程、有限体积法在计算网格上离散求解、VOF方法追踪自由水面;采用C语言编写用户自定义函数,以泥沙起动切应力作为床面泥沙起动判别标准,通过分析比较水流剪切力与泥沙起动切应力大小,用以控制冲刷坑底部边界变化;采用局部重构模型和弹簧光顺模型更新计算区域和网格质量,藉以模拟和追踪局部冲刷坑边界变化。研究表明,模拟结果与实测资料符合良好。在冲刷坑的冲刷过程中,床面剪切应力随着冲刷的进程急剧减小,湍动能随着冲刷的进程减小缓慢;床面剪切应力和湍动能沿程变化均较为剧烈,床面剪切应力沿程先增大后减小,床面湍动能则沿程减小。冲刷坑的纵向平衡形态或床面泥沙起动主要决定于床面剪切应力,床面湍动能对泥沙起动也具有重要影响。     

间歇窑窑墙温度场图形仿真研究

本文利用有限差分法求解间歇窑窑墙中的温度分布，并用Ｃ语言设计了窑墙温度场图形仿真软件。输入窑墙厚度和材料的物性参数等，系统可进行窑墙温度场分布的实时仿真及窑炉结构与操作的优化     

计算机网络安全与防护技术研究

本文主要对计算机网络安全产生的根源和存在的风险进行了初步分析,对目前常用的网络安全技术进行了较为深入的研究,并阐述了防火墙技术与入侵检测技术在计算机网路中联合部署的方法和步骤.     

Adhesion-Delamination Mechanics of a Prestressed Circular Film Adhered onto a Rigid Substrate

A thin circular film clamped at the periphery is adhered to the planar surface of a rigid cylindrical punch. An external tensile load is applied to the punch, causing the film to delaminate from the substrate and the circular contact edge to contract. The film spontaneously separates from the punch, or pulls off, when the contact radius reduces to a range between 0.1758 and 0.3651 of the film radius, depending on the magnitude of the residual membrane stress. The mechanical delamination process is derived by a thermodynamic energy balance based on a coupled interfacial adhesion and residual membrane stress. The theoretical model has significant implications in nanoforce measurement, microelectromechanical systems (MEMS) comprising active moveable films, and biological cell adhesion.     

Heat transfer of gas flow through a packed bed

This paper reports an experimental study of both the transient and steady-state heat transfer behaviour of a gas flowing through a packed bed under the constant wall temperature conditions. Effective thermal conductivities and convective heat transfer coefficient are derived based on the steady-state measurements and the two-dimensional axial dispersion plug flow (2DADPF) model. The results reveal a large temperature drop at the wall region and the temperature drop depends on the axial distance from the inlet. The 2DADPF model predicts the axial temperature distribution fairly well, but the prediction is poor for the radial temperature distribution. Length-dependent behaviour of the effective heat transfer parameters and non-uniform flow behaviour are proposed to be responsible. A comparison with previously published correlations and data in the literature shows that the relationships proposed by Bunnell et al. and Demirel et al. agree well with the measured effective radial thermal conductivity, whereas the wall-fluid heat transfer coefficient is better represented by the Li-Finlayson correlation.