Study of elementary reactions of free radicals formed on oxide and platinum containing catalysts

The formation of alkylperoxy radicals on catalysts CuCr₂O₄/ -Al₂O₃, Pt /--Al₂O₃ and on alumina upon the interaction of amines and alcohols with oxygen has been observed applying the matrix isolation ESR technique. Surface-generated gas phase radicals are shown to initiate a radical chain reaction. The efficiency of the yield of radicals depends on the catalyst mass and its arrangement in a reactor: the desorption of radicals into the gas phase occurs primarily from the outer geometrical surface of catalyst granules.     

梯形聚甲基／苯基倍半硅氧烷耐高温涂料的制备和性能测试

选用自制的梯形聚甲基倍半硅氧烷和梯形聚苯基倍半硅氧烷为基料制备出了耐高温涂料(PRSI)。测试结果表明,自制涂料PRSI的热分解温度可达597℃,具有很好的热稳定性、耐盐水性和耐化学性能,还具有较小的表面张力。     

多管程管壳式换热器管箱法兰的强度计算

多管程、高压、高温换热器管箱法兰的垫片密封问题对法兰强度的影响 ,在有关的标准规范中没有相关说明 ,设计中往往被忽略了。通过计算实例进行分析 ,可见其影响有时还比较大 ,建议通过折算进行强度计算 ,确保其安全可靠。     

磷矿的风化反应与酸解活性的关系

通过对磷矿风化水解反应的分析，说明风化反应与磷矿的化学组成及微观结构有着密切的联系。磷矿中碳酸盐的含量及在磷矿晶体中的存在状况对磷矿的酸解反应活性有着较大的影响。由磷矿酸解反应活性与磷矿晶体微观结构的关系，指出易风化的磷矿具有较好的酸解反应活性。     

多氯乙酰氯的气相色谱分析

用气相色谱TCD和FID检测器对多氯乙酰氯及其酯化产物的成分和纯度进行了分析，用正丙醇对其进行衍生化，酯化率大于99．6％，生成的酯化产物用毛细管色谱法分析，其方法的分离效率高，重现性好，检测结果准确可靠，9次分析的变异系数0．45％，在工业产品的检测中取得满意的结果。     

管壳式换热器数值模拟的流动模型比较

基于计算流体动力学（CFD）技术,分别用LVEL模型、标准k-ε模型对管壳式换热器进行数值模拟,并把内管入口和出口的流动方向速度进行对比,依此判断计算的准确性,来寻找适合于管壳式换热器数值模拟的合理模型.经过计算可以判断：LVEL模型和标准k-ε模型计算出的流场基本一致.LVEL模型已足够准确、耗时也较小,对于管壳式换热器的数值模拟是适用的,是做换热器模拟时一种较好的选择.     

张弦式网壳结构中的拉索预应力值设计方法的应用研究

依据大跨度网壳结构的几何非线性特性,采用几何非线性有限元技术,按预应力控制网壳变形的原则,并结合武汉体育中心体育馆张弦天穹网壳实际工程,对预应力值的设计做了研究,提出了一种新的预应力方法.该方法具有简便实用,具有明确的物理意义,并在实际工程应用中取得了理想的结果.     

一类椭圆-抛物耦合方程组弱解的衰减估计

该文研究在热效应影响下半导体模型,它归结为一个非线性椭圆-抛物耦合方程组初边值问题.考虑此半导体方程瞬态解和稳态解之间的关系,通过对解的一系列估计,给出了在一定条件下瞬态解与稳态解的一个衰减估计.     

Thermophysical Analysis of Sandstone by Pulse Transient Method

Stones belong to porous materials where water in pores plays an important role during the freeze–thaw process. A thermophysical analysis based on the pulse transient method has been used to study an ageing cycle, namely the freeze–thaw cycle. Thermophysical analysis is based on measuring the thermophysical properties under specific thermodynamic conditions. The transient method determines the specific heat, thermal diffusivity, and thermal conductivity by a single measurement. A specimen of Sander sandstone was analyzed in both dry and water-saturated states. Typical anomalies of all thermophysical parameters at the freeze–thaw point as well as differences for the dry and saturated states were found. The changes of thermophysical parameters measured when using freeze–thaw cycles correspond to stone ageing. The freeze–thaw cycle can often be encountered in building physics, concrete construction, etcPaper presented at the Seventh Asian Thermophysical Properties Conference, August 23–28, 2004, Hefei and Huangshan, Anhui, P. R. China.     

Effect of near-critical swirl on the Burke-Schumann reaction sheet

The influence of swirl on the shape of the Burke-Schumann reaction sheet in a straight cylindrical pipe is investigated by asymptotic and numerical means. Attention is confined to swirl levels that are near the critical value at which vortex breakdown occurs. A high-Reynolds-number, laminar, isothermal, low-Mach-number reacting flow is considered. An asymptotic analysis is developed to study the nonlinear interaction between near-critical swirl and mixture fraction distribution within the flow. It is first shown that leading-order perturbation of the velocity field from the columnar state, generated by the interaction of near-critical swirl and low viscosity, can be described by a nonlinear reduced-order model. This flow perturbation is computed, and then employed to determine the correction to the classical Burke-Schumann solution. Under lean conditions of reaction the reaction sheet becomes shorter and more compact as swirl is increased. For rich conditions of reaction, increasing swirl first causes the reaction-sheet length to decrease, and then increase after vortex breakdown has appeared. Numerical simulations of the flow and reaction-zone shape are substantiated by, and supplement, the asymptotic results.