对材料试验机负荷-夹头位移曲线的剖析

本文剖析了材料试验机自动绘图设备所绘出的负荷-夹头位移曲线.指出在楔形夹头中,夹头对试样的啮合变形所引起的夹头位移,在夹头总位移中占有不可忽视的比重.其随负荷增加的变化规律及其在负荷-夹头位移曲线各阶段中的比重是不同的.     

甲醇在HNaY及Pd-碱金属Y沸石上的分解反应

采用脉冲微型反应色谱研究了甲醇的分解反应。甲醇在HNaY沸石上的分解活性随着钠离子被交换程度的增加而增加。当交换度小于60%时,甲醇的脱水和脱氢反应同时发生,并以脱水反应为主;当交换度超过80%时,HNaY沸石的脱氢活性消失。在含有碱金属离子的Pd/MY(M=碱金属)沸石上,甲醇的主要分解产物是CO和H_2。与LiY、NaY、KY和CsY沸石相比较,载钯后沸石在脱氢反应中活性明显增高,其活性顺序如下:Pd/CsY>Pd/NaY>Pd/LiY>Pd/KY     

循环床内气固两相流中稠密颗粒间碰撞的数值模拟

循环床内部的流动属于复杂不均匀的稠密气固两相流，稠密颗粒间的相互作用是影响颗粒运动和浓度分布的不可忽视的重要因素。本文采用直接模拟Monte－Carlo算法（DSMC算法）来模拟颗粒间的相互碰撞过程，并与随机轨道模型结合起来综合考虑湍流和颗粒碰撞对颗粒运动和浓度分布的影响，模拟结果预报了床内分层流动结构和颗粒在稀相区的不均匀分布，计算结果与实验定性符合。     

PHOTOPOLYMERIZATION INITIATED BY DIMETHYLAMINOCHALCONE/DIPHENYLIODONIUM SALT COMBINATION SYSTEM SENSITIVE TO VISIBLE LIGHT

Several dimethylamino-substituted chalcone (i .e. dimethylaminobenzal acetophenone) (DBA) derivatives with intramolecular charge transfer transition character were used as visible light sensitizers for radical photopolymerization initiated by iodonium salt (DPIO). Initiating radical species is produced from DBA sensitized photolysis of DPIO through the single electron transfer, accompanying the bleaching of DBA, The activity of DBA decreases as a function of substituent attached to phenyl ring in the order: DBA-2 (OCH_3) >DBA-1(H)> DBA-3 (Cl). The kinetic study on photopolymerization of MMA was carried out in CH_3CN solution at 30 ℃by dilatometry. The polymerization rate was determined to be proportional to the concentration with exponents of 0.42, 0.25 and 0.86 for DPIO, DBA-1 and MMA, respectively.     

质点在有心力场中运动轨道的稳定性

本文探讨质点在有心力场中运动轨道的稳定性问题．运用李亚普诺夫关于运动的稳定和不稳定性定理，证明在幂次定律形式的 力场中，质点在平方反比场中运动的椭圆、抛物线和双曲线三种轨道都是稳定的，这是这种 力场所具有的性质；质点在弹性引力场中运动的椭圆轨道也是稳定的，而在弹性斥力场中运动的轨道一般是不稳定的．文中对其它有心力场也作了一些讨论．     

金属薄板弹性各向异性检测

当平面声波入射到液体中的金属薄板上时，透射系数将随声波入射角变化，根据这一规律，能够准确地测定声波入射面与金属薄板交线方向上金属板材料的弹性常数，测得金属薄板面内不同方向的弹性常数，对金属薄板弹性各向异性情况将有一清蜥的认识，由于测试过程采用微机控制、数据采集和处理，实现了各向异性测量的全自动化，该方法测试时间短、所需样品小且加工方便，并可测试金属薄板弹性各向异性的均匀度。     

A SENSITIZED PHOTOINITIATION SYSTEM ——BIS (7-DIETHYLAMINO COUMARIN ) KETONE-3 AND DIPHENYLIODONIUM SALT COMBINATION

Bis (7-diethylaminocoumarin) ketone- 3(DACK) and diphenyliodonium salt (DPIO)combination as an effective photoinitiation system for radical polymerization has been investigated. The sensitized photolysis of DACK/DPIO leads to bleaching of DACK and decomposition of DPIO to generate initiating radical species. The electron transfer sensitization occurs mainly from the triplet state of DACK. The photobleaching obeyed a second-order kinetics and the rate constant was evaluated to be 31.3mol~(-1)·1·s~(-1) Photopolymerization of MMA initiated by DACK/DPIO was carried out in acetonitrile solution. The polymerization rate was found to be proportional to the concentration of DACK, DPIO and MMA with the exponents of 0.34, 0.40 and 1.0 respectively. The initiated efficiency is comparable to those of small molecular ketones.The sensitized photoinitiation mechanism has been discussed.