Studies on the dielectric and relaxor behavior of sol-gel derived barium strontium zirconate titanate thin films

The dielectric behavior of sol-gel derived Ba_0.80Sr_0.20(Zr_xTi_1−x)O₃ (0.0 ≤ x ≤ 0.50) thin films is studied. A relaxor behavior is observed for x ≥ 0.35. The degree of relaxation increases with Zr content. The frequency dependence of the polar regions follows Vogel-Fulcher relation with a characteristic cooperative freezing at freezing temperature (T_f). Below T_f, a long range polarization ordering is likely to take place. The plausible mechanism of the relaxor behavior of BSZT thin films with Zr contents ≥ 0.35 has been proposed based on the measured temperature as well as frequency dependent dielectric data. The solid solution system is visualized as a mixture of Ti^+ 4 rich polar regions and Zr^+ 4 rich regions; with the increase in Zr content the volume fraction of the polar regions is progressively reduced. At and above 35.0 at.% Zr substitution the polar regions exhibit typical relaxor behavior.     

可溶性盐复分解法碳酸钙制备影响因素研究

采用可溶性盐复分解法进行碳酸钙合成影响因素及其机理的研究。以正交试验法对合成温度、pH值、反应物浓度在碳酸钙合成中的影响进行探索,验证了温度以及pH值在合成反应中对产物晶型、形貌以及尺度有显著影响;使用周期键链理论(PBC)讨论了碳酸钙晶体方解石/文石共生现象;研究观察Mg2+对碳酸钙合成的影响,Mg2+作为能够稳定无定形碳酸钙前驱体(ACC)的金属离子,大量存在时碳酸钙形貌随nMg/nCa增大而变化,同时颗粒尺度变小。     

Thermal conductivity of water and 2-n-butoxyethanol and their mixtures in the temperature range 305–350 K at pressures up to 150 MPa

The thermal conductivity of binary liquid mixtures of water and 2-n-butoxyethanol has been measured within the temperature range 305–350 K at pressures up to 150 MPa. The measurements have been carried out with a transient hotwire instrument suitable for electrically conducting liquids and have an estimated accuracy of ±0.3%. The liquid mixture has a closed-loop solubility and reveals a lower critical solution temperature for a mole fraction of 2-n-butoxyethanol of 0.0478 at a temperature of 322.25 K. The results of the measurements reveal a small, but discernible, enhancement of the thermal conductivity of the solution at the critical composition.Paper presented at the Twelfth Symposium on Thermophysical Properties. June 19–24, 1994, Boulder, Colorado, U.S.A.     

化学气相沉积传质现象的研究与反应器设计、工艺参数的优化

介绍了化学气相沉积中的传质现象研究的最新进展,从传质方程的建立到边界条件确定都进行了详细的介绍,并举例说明了数值分析的结果的反应器设计与工艺参数的优化的指导作用。     

The effect of the trapping of dust grains on the sheath structure and the charging in a plasma

A model of the trapping of dust grains is shown in a plasma for the first time. The multiple sheath potential, the space charge density and the multiple electric field associated with our model are simulated. Our result explains the confinement of the dust grains observed in the experiment.     

Image-plane measurements of coexistence curve diameters

The diameter of the coexistence curve has been measured for several fluids to determine differences from linear form. The experimental method consists of optical interference measurements in a Mach-Zehnder interferometer supplemented by measurements of deviation in a hollow prism. The fluid sample is contained in a temperature-stabilized cell in one branch of the interferometer. A variation in cell temperature causes the density profile within the cell to change, resulting in a change of the interference pattern, which is monitored photographically. From the relation of this pattern at any temperature to the pattern at the critical temperature, information on the refractive indices of the liquid and vapor phases is obtained. This information is combined with measurements of the Lorentz-Lorenz coefficient to obtain liquid and vapor densities along the coexistence curve. The average of liquid and vapor densities is analyzed in terms of RG theory. The results of the experiment yield information on three body interactions. Studies have been completed on ethane, ethylene, hydrogen, and fluoroform.Paper presented at the Tenth Symposium on Thermophysical Properties, June 20–23, 1988, Gaithersburg, Maryland, U.S.A.     

Transport properties of critical dilute solutions

On the basis of the isomorphism of critical phenomena, the behavior of transport properties of binary mixtures in the vicinity of the vapor-liquid critical line is considered. In particular, the renormalization of the singularity of the thermal conductivity in dilute critical solutions has been analyzed in detail. It is shown that the behavior of the thermal conductivity is determined by the critical background, i.e., the fluctuation-induced regular part, which diverges at the critical point of a solvent.     

考虑排污权交易的有限理性企业博弈模型研究

在有限理性基础上建立寡头垄断博弈模型,将其引入到排污权市场中,同时考虑了生产成本、污染治理成本、排污权交易价格的影响,使该模型更符合实际。将不同理性层次,不同结构的非线性成本函数,不完全信息等因素引入到博弈模型中,对改进后的模型的演化过程进行分析,找出博弈均衡点,并分析其稳定性。由于具有有限理性的双寡头Cournot博弈模型会产生丰富的动力学行为,因此对其进行数据模拟后并对混沌现象进行分析。在此基础上,运用延迟反馈控制法对寡头垄断博弈模型的混沌控制进行了解析分析,结果表明选择合适的控制因子可使模型稳定在Nash均衡。     

概率论数字实验室

构建了概率论和随机现象计算机模拟仿真演示系统。该系统包括六个子系统：人机界面、内核、集合论,概率分布、随机现象和帮助子系统。该系统可以完成的模拟演示包括：集合运算、教材中常见的概率密度函数和累积概率分布函数、概率游戏、概率论题解以及蒙特卡洛模拟等。学习者应用该系统可以对抽象的概率论理论、运算以及相关随机现象进行形象直观地观察和研究,该系统在概率论的教学中起到了类似实验室的作用,弥补了概率论常规教学中难以进行实验观察的不足。     

CPLD在客车轻便换挡控制系统中的应用

介绍了一种基于CPLD的单片机控制系统的软硬件设计方法。并以ATF1504为代表的CPLD在客车换挡系统中的应用为实例,给出了相应的原理介绍有逻辑图,分析了CPLD在控制系统中的优越性及实现方法,并总结了一些应用经验。