双轴取向聚对苯二甲酸乙二酯的热收缩及热机械分析

本文用热机械及示差扫描量热热分析技术对聚对苯二甲酸乙二酯双轴取向拉伸膜的热收缩特性进行了研究,并对热收缩的机理进行了探讨。     

电磁制冷机的发展

介绍了一种利用顺磁盐物质的磁热效应获取低温进行制冷的方法。对电磁制冷机的原理及其发展进行了综述,并指出提高其制冷效率的途径。     

Numerical Simulation and Experimental Studies of Air Treatment Process with Water Spray of One Row Counter Flow

The present work is focused on heat and mass transfer in a direct evaporative air cooler of one row counter flow spray. Models of the two-phase flow in such a air treatment system have been developed. The fields of temperature and relative humidity in spray chamber, as well as the trajectories of sprayed drops have been obtained by numerical method. Experiments aiming at quantifying the system performance and its influence factors have been conducted. It indicates that the increase of air velocity and water/air ratio while thedecrease of nozzle density are favorable. The performance of the system of parallel flow spray and counter flow spray have been compared by means of humidifying efficiency. Comparison between numerical simulation and experimental results demonstrate good agreement for outlet air temperature with a maximum error of 8% observed for air relative humidity.     

自蔓延高温合成TiC-Al的热力学计算与分析

对Al-Ti-C三元体系进行了热力学计算,绘出了反应的标准自由焓随温度变化的曲线、绝热温度随Al含量变化的曲线以及绝热温度随预热温度变化的曲线.分析表明:三元体系的主要反应是Ti C=TiC.体系的绝热温度随Al含量的增加而下降,当预热温度为650 K时,Al最佳的理论含量约57.5%,体系的绝热温度随预热温度的升高而升高;若Al含量过大,体系的绝热温度小于1800 K时,可以适当的提高预热温度,来确保反应的自发进行.     

Measurement of Crystallinity of Acrylic Copolymer by Swelling Differential Scanning Calorimetry

In this paper the measurement of crystallinity(C)ofacrylic copolymer(PAC),by Swelling Differential Scan-ning Calorimetry(SDSC)is discussed.Common DSC isonly used for measuring the crystallinity of polymers withmelting point,(T_m),below their decomposition temper-ature,(T_d).As temperature rises,polymers with swell-ing agent added become swollen and dissolved,goingthrough whole process of breaking solid structures.Thus,SDSC makes it possible to measure the crystallini-ty of polymers even with T_d below T_m.But the C mea-sured by WAXD and the total endothermal melting(swelling)heat in SDSC thermograms,(△H_l),are notlinearly correlated.It has been found that,instead of the△H_l,△H_l'obtained from the △H_l by subtracting the en-dothermal heat,△H_l,and the C measured by WAXDare linearly correlated.On the basis of this linear rela-tion,the unknown C of another PAC sample is measuredby SDSC.The result is in good accordance with thatmeasured by WAXD.     

Using time-resolved photo鈉oustic calorimetry to study triplet energy and lifetime for benzophenone-KI system

Time-resolved photoacoustic calorimetry has been expanded to allow the simultaneous determination of the dynamics and energetics of photoinduced reaction occurring on fast timescales, principally ns and μs. Data analysis requires deconvolution of photoacoustic signals for a sum of exponentials. This technique with PZT transducer is now first applied to investigating the quenching of the benzophenone triplet state by KI in methanol, and gives kinetic and thermodynamic results in excellent agreement with the previous value in acetonitrile.     

金属固体材料杨氏模量的静态拉伸法测量改进

从金属固体材料(如:钢丝)长度、镜尺间距、光杠杆前后足间距和视伸长的测量等方面对现有的实验仪器和测试方法进行改进,降低了调节的难度,简化了实验操作,减小了实验误差,可以达到提高测量精确度的实验要求。     

非线性绝热条件下的级联高效非线性光频转换

理论上研究了级联二阶非线性光学效应产生三次谐波中的非线性耦合与能量转移过程.依据受激拉曼绝热通道转移(STIRAP)原理和暗态特征,获得了非线性系统中的非线性绝热条件、分析了实现高效能量转换的物理机理,提出了实现能量完全转换时耦合系数应该满足的基本条件.研究结果对于设计产生三次谐波的光学器件具有重要意义.     

相空间中离散完整系统Mei对称性摄动与绝热不变量

研究相空间中离散完整系统Mei对称性摄动和绝热不变量。给出未受扰动系统Mei对称性导致的精确不变量,讨论在小扰动作用下系统Mei对称性的摄动,得到系统的Mei对称性摄动导致的绝热不变量。最后举例说明结果的应用。     

Effect of B alloying on magnetocaloric effect of Gd5.1Si2Ge2 alloy in low magnetic field

A series of the Gd_(5.1)Si_2Ge_(2-x)B_x,alloys were prepared with arc melting in purified argon atmosphere.The effect of B addition on the magnetocaloric effect of compound Gd_5Si_2Ge_2 was investigated by powder X-ray diffraction technology and DSC and direct magnetocaloric effect apparatus and vibrating sample magnetometer(VSM).The results show that the addition of a small amount of B maintains the Gd_5Si_2Ge_2 compound in single monoclinic phase with superior magnetocaloric effect,especially when x=0....