An aqueous gel-casting process for γ-LiAlO2 ceramics

Methyl cellulose (MC) was used as the gelation agent in the gel-casting of γ-LiAlO₂ because it could form strong gels during heating. The thermal gelation behavior of the MC solution was studied based on the measurement of its apparent viscosity as a function of temperature. The effects of MC solution concentration and solid loading on the rheological properties of the γ-LiAlO₂ slurries were studied systematically. It was found that all the slurries exhibited a shear-thinning behavior, which was considered to be favorable for the casting process. The compressive strength and relative density of the dried γ-LiAlO₂ green bodies were measured, and the microstructure of the green and sintered bodies was investigated.     

Pulsed CH<Subscript>3</Subscript>OH Terahertz Laser Emission Pumped by a TEA CO<Subscript>2</Subscript> Laser

A simple terahertz (THz) cavity and a TEA CO₂ laser for the optically pumped THz emission is studied experimentally. To obtain high peak power of pump laser, pressure ratios of gas mixture in the cavity of the TEA CO₂ laser are discussed. When CH₃OH are pumped by the 9P(16) and 9P(36) CO₂ laser lines, the generation of terahertz radiation with energy as high as 353 μJ and 307 μJ are obtained, respectively. The corresponding photon conversion efficiencies are 0.705% and 0.29%. Meanwhile, higher peak power of pump laser effectively improves the photon conversion efficiency. And the optimum THz laser pressure increases with narrower pulse width of pump laser.     

偏心蝶式止回阀开启性能瞬态分析

采用计算流体力学分析软件Autodesk Simulation CFD及其重叠网格技术,对偏心蝶式止回阀的两种阀板结构分别进行了开启特性瞬态分析。基于粘性可压缩流动Navier-Stokes方程进行了湍流非定常计算,对两种阀板结构的阀板运动状态、阀内的压力分布和速度矢量进行了分析及对比。结果表明,原阀板结构开启过程中存在不稳定且未达到预期的全开状态,改进阀板结构开启过程中阀板开度呈线性增加且稳定在全开位置。     

酸碱性环境及表面活性剂对润滑油生物降解的影响

选用蓖麻油和矿物油基液压油2种不同类型的润滑油作为研究对象,研究不同pH值环境条件下润滑油的生物降解,考察表面活性剂类型及浓度对润滑油生物降解的影响。研究表明,碱性条件下有利于植物油基润滑油的生物降解,酸性环境则有利于矿物油基润滑油的生物降解;阴离子及非离子表面活性剂能促进润滑油的生物降解,而阳离子表面活性剂则会阻碍润滑油生物降解;表面活性剂在临界胶束浓度以下促进生物降解能力较强,高于临界胶束浓度则效果相反。     

屏蔽电磁干扰高分子磁性复合材料的研究

与铁氧化比较，二茂铁高分子磁性材料（OPM）在100MHz以下，其频率－磁导率（f-μ′）及温度－磁导率（T－μ′）变化不大，研究了金属纤维及碳纤维填充的OPM复合材料及其配位金属（Cu,Co,Ni)类型，屏蔽形式对屏蔽效果（SE）的影响。     

共焦自聚焦光纤传感器回波干扰抑制方法分析

基于共焦原理的自聚焦光纤传感器将共焦光路、自聚焦透镜和光纤集于一体，实现了微型化和轴向高分辨率的统一，可用于内外曲面的微观形貌、坐标尺寸和曲面轮廓等的高精度检测。运用高斯光束传输原理和矩阵光学理论对影响传感器信号强度的端面回波问题进行了理论分析，提出了解决回波问题的技术途径。实验结果说明，通过对不同端面采用不同的抑制方法，回波问题被较好地解决。     

基于四次方程的三角解研究非球对称动态黑洞的"类视界面"

给出了具有实用价值的四方程的三角解正根公式，并以匀加速直线运动的Kerr黑洞为例，成功的研究了非球对称动态黑洞的“类视界面”。     

硼氮化改性菜籽油润滑添加剂的摩擦学性能研究

在菜籽油中引入硼、氮 ,合成了四种新型润滑油添加剂———硼氮化改性菜籽油润滑添加剂。通过四球试验机考察了它们在菜籽油和水中的抗磨性能与极压性能。结果表明 ,4种硼氮化改性菜籽油润滑添加剂均具有明显的减摩、抗磨和极压性能。其润滑作用机理是由于长链菜籽油分子的载体作用、硼的缺电子、氮的反应活性以及三者的协同作用与摩擦金属表面形成了一层高强度的吸附膜和 /或摩擦化学反应膜。     

计算机在建筑工程造价中的应用

简要介绍了目前建筑工程预算软件的发展过程和我国目前使用较广、具有一定特色的预算软件的功能特点．及IT技术在我国工程造价管理工作中应用情况．