Mg17 Al12、Al2Ca、Al2Nd、Al2Er金属间化合物稳定性与电子结构的第一性原理研究

采用基于密度泛函理论的Castep程序软件包,优化了Mg17Al12、Al2Nd、Al2Er及Al2Ca相晶胞结构,计算了化合物的形成热、结合能和态密度等,分析了化合物结构稳定性与其电子结构的内在联系。结果表明:四种化合物的形成热和结合能均为负值,且化合物的合金化能力和结构稳定性强弱顺序依次为Al2Er、Al2Nd、Al2Ca、Mg17Al12。态密度结果表明: Al2Er和Al2Nd具有较强结构稳定性的主要原因是（1）在费米面低能级区Al(3p)轨道分别与Nd(4f)、(5d)和 Er(4f)、(5d)轨道价电子发生强烈杂化作用;（2）Al2Nd和Al2Er成键电子数较多;（3）这两种化合物的电子参与成键能力较大。电荷密度结果表明：Mg17Al12、Al2Ca、Al2Nd、Al2Er中均存在金属键、离子键、共价键,四种化合物中Al2Er、Al2Nd共价键较强,Al2Ca离子键最强,Mg17Al12中以较强的金属键为主。     

Theoretical and experimental studies on low-temperature adsorption drying of fresh ginger

The working principle of low-temperature adsorption drying and the advantages of its application for biological materials drying were introduced in this paper. By using fresh ginger as the drying material, the effects of temperature and relative humidity on its drying characteristics were examined. The results show that the drying rate increases with the temperature increasing or the humidity decreasing. The drying time to the equilibrium is almost the same under different humidity conditions, but low equilibrium moisture content can be acquired under low humidity. The shrinkage characteristics of fresh ginger were also studied. The change of its surface appearance during the drying process was characterized by the new Charged Coupled Device (CCD) and the Environmental Scanning Electron Microscopy (ESEM) technique. A mathematical model of drying dynamics was set up according to the experiments.     

Probabilistic capacity of a grid connected wind farm based on optimization method

This paper proposes a new method to find the capacity of a future wind farm regarding several limits of the grid system: voltage stability limits, thermal limits, voltage limits, load tap changing limitation and generator power output limitation. The method combines the optimization method and a probabilistic analysis to maximize the number of the wind turbines subject to those limits. Two types of wind farms are modeled in this paper: fixed speed wind farms and variable speed wind farms. It is concluded that the proposed method is a fast and accurate method to deal with the uncertainty of wind energy in the planning of wind farm capacity.     

多效回热降膜蒸发式太阳能液体除湿空调溶液再生器的稳态实验

设计了一种具有多效回热可用于太阳能液体除湿空调系统的溶液再生器,用碘钨灯作为模拟太阳光源对系统进行了稳态实验,得到出口浓度与光辐射强度、溶液流量、强迫对流风速和入口溶液浓度的关系曲线,给出了系统性能系数与太阳光强度的关系,并对装置的传热传质关系作了简化计算,对影响系统性能的其他因素也进行了分析。实验结果表明,由于系统采用了多效回热措施,系统的回热率相对太阳辐射能来说达到32%。由实验结果估计,在晴好天气条件下,该系统每天每平方米集热器可处理LiBr溶液量(47%～52%)约86kg。     

Synthesis and characterization of sulfonated poly(arylene ether ketone ketone sulfone) membranes for application in proton exchange membrane fuel cells

A series of sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS) copolymers were synthesized by nucleophilic polycondensation. The copolymers exhibit good thermal and oxidative stabilities, all the SPAEKKS copolymers can be cast into tough membranes. Ionic exchange capacities (IEC), water uptake properties, thermal stabilities, methanol diffusion coefficients and proton conductivities were thoroughly studied. Also the microstructures of the membranes were investigated by TEM. The proton conductivity of the SPAEKKS-4 membrane is close to that of Nafion-117 at 80 °C. The methanol diffusion coefficient of the membrane is much lower than that of Nafion-117 under the same testing conditions. The SPAEKKS membranes are promising in proton exchange membranes fuel cell (PEMFC) application.     

油焦浆枪的雾化性能及在电厂中的应用

介绍一种利用炼油厂下脚料油焦与水混合制作的油焦浆混合物及其特性,并简要介绍了将油焦浆替代电厂燃油时油焦浆枪的雾化性能、运行性能及在电厂中的实炉应用效果.结果表明,油焦浆枪雾化及运行性能良好,用油焦浆替代燃油不仅可行,而且效益可观.     

高硫石油焦的工业利用前景分析

随着高硫原油产量的增加,高硫石油焦的产量也在增加。除利用高硫石油焦作锅炉燃料之外,有3种大量或专门燃烧石油焦的技术,即作水泥窑的燃料、循环流化床(CFB)锅炉和气化联合装置(IGCC)。为此介绍和比较了上述3种技术,分析了我国高硫石油焦的工业利用前景。循环流化床(CFB)锅炉技术将是我国高硫石油焦应用的发展方向。     

某石化企业电厂布袋除尘器的改造

分析了某石化企业自备电厂4号炉布袋除尘器运行过程中出现的问题,提出了相应的解决方法。经过改造后,设备运行良好。     

KM186型柴油机的研制开发

本文介绍了KM186型柴油机的开发背景及设计目标,主要零部件的优化设计过程以及通过大量试验所获得的各项良好指标。     

SF_6断路器喷口形状尺寸对烧蚀的影响及喷口设计方法探讨

本文着重分析了断路器喷口的形状尺寸,喷口内气动参数对其烧蚀的影响。根据喷口的经验数据和气流场的计算公式,总结出断路器喷口设计的估算方法。