无机固态材料中气体元素分析的现状与进展

本文介绍了气体元素分析样品表面处理的最新研究成果,综述了热导法、红外吸收法、库仑滴定法、飞行时间质谱法和火花源原子发射光谱法等分析方法在无机固态材料气体分析中的应用现状,分析了各自的特点及存在的问题,并展望了气体分析的发展方向(引用文献85篇)。     

高师“化学教学论实验”课程项目化学习的教学实践探索

立足于教学实践,探讨了"自主、合作、探究"模式下高师"化学教学论实验"课程中项目化学习的设计思路、实施模式和实施程序。教学实践说明将项目化学习应用于"化学教学论实验"课程,能够有效提升化学师范生的实验教学能力。     

17世纪比利时著名的化学家——范·海尔蒙特

范·海尔蒙特是比利时化学家,因"柳树实验"闻名于世,创建了定量分析的化学研究方法,发现二氧化碳并提出化学术语"气体",是气体化学研究的奠基人。通过回顾海尔蒙特的研究生涯,感受他淡泊名利、坚持不懈、默默无闻的研究精神和品质。     

职前化学教师实验教学表现性评价研究——以“化学教学论实验研究”教学为例

教学评价要与课程设置和教学活动整合起来。以化学教师教育课程群的主干课程"化学教学论实验研究"为例,将国外教师表现性评价方案本土化后,形成"课前、课中、课后"全过程的表现性评价量表。结合国内本门课程教学模式特色,将量表的使用镶嵌于该门课程的教学过程中。以清晰的表现性目标、具体的表现性任务、明确的评分规则,解困该课程学习者众、指导者寡、教学要求高、课时少的窘境,从而将表现性评价理念落到实处,促进职前化学教师自我引导的专业学习,促进课程质量和教学效率的提升。     

机场航站楼安检通道数量配置优化方法研究

科学配置机场航站楼的安检通道数量,是提高安检服务效率、保障民航运输安全的重要手段.通过对机场航站楼的安检排队系统进行特征分析,利用排队理论建立两种安检排队模型.调研国内典型机场的实际运行数据,计算安检排队模型的主要运行指标,分析各指标的变化规律,并针对两种排队模型的运行效率进行对比.结果表明,排队系统的平均排队长和旅客平均等待时间均呈周期性变化,安检通道最少配置数量随着旅客到达率的增加而增加,单队多服务台系统在理论上比单队单服务台系统的运行效率更高.研究成果为优化机场航站楼安检通道数量配置、提高安检运行效率提供理论依据与决策支持.     

POLY-SCALE REFINABLE FUNCTION AND THEIR PROPERTIES

Poly-scale refinable function with dilation factor a is introduced. The existence of solution of poly-scale refinable equation is investigated. Specially, necessary and sufficient conditions for the orthonormality of solution functionφof poly-scale refinable equation with integer dilation factor a are established. Some properties of poly-scale re-finable function are discussed. Several examples illustrating how to use the method to construct poly-scale refinable function are given.     

FLOW STRUCTURE FORMATION AND EVOLUTION IN CIRCULATING GAS-FLUIDIZED BEDS

The occurrence of heterogeneous flow structures in gas-particle flows seriously affects the gas-solid contacting and transport processes in high-velocity gas-fluidized beds. Particles do not disperse uniformly in the flow but pass through the bed in a swarm of clusters. The so-called “core-annulus“ structure in the radial direction and “S“ shaped axial distribution of solids concentration characterize the typical flow structure in the system. A computational study, using the discrete particle approach based on molecular dynamics techniques, has been carried out to explore the mechanisms underlying formation of the clusters and the core-annulus structure. Based on energybudget analysis including work done by the drag force, kinetic energy, rotational energy, potential energy, and energy dissipation due to particle-particle and particle-wall collisions, the role of gas-solid interaction and inelastic collisions between the particles are elucidated. It is concluded that the competition between gas-solid interaction and particle-particle interaction determines the pattern formation in high-velocity gas-solid flows: if the gas-solid interaction (under elevated pressure) dominates, most of particle energy obtained by drag from the gas phase is partitioned such that particle potential energy is raised, leading to a uniform flow structure. Otherwise, a heterogeneous pattern exists, which could be induced by both particle -particle collisions and gas-solid interaction. Although both factors could cause the flow instability, the non-linear drag force is demonstrated to be the necessary condition to trigger heterogeneous flow structure formation. As gas velocity increases and goes beyond a critical value, the fluid-particle interaction suppresses particle collisional dissipation, and as a consequence a more homogeneous flow regime is formed.     

CFD SIMULATION OF FLUID CATALYTIC CRACKING IN DOWNER REACTORS

A mathematical model has been developed for the simulation of gas-particle flow and fluid catalytic cracking in downer reactors. The model takes into account both cracking reaction and flow behavior through a four-lump reaction kinetics coupled with two-phase turbulent flow. The prediction results show that the relatively large change of gas velocity affects directly the axial distribution of solids velocity and void fraction, which significantly interact with the chemical reaction. Furthermore, model simulations are carried out to determine the effects of such parameters on product yields, as bed diameter, reaction temperature and the ratio of catalyst to oil, which are helpful for optimizing the yields of desired products. The model equations are coded and solved on CFX4.4.     

两相正激波松弛流的数值研究

对气、固两相正激波松弛流动进行了数值研究,方程中考虑了压力梯度及非匀速运动引起的附加质量力。给出了完整的计算方法,对三种不同固相容积比、不同固相颗粒直径和不同马赫数分别进行了数值计算,所得计算结果给出了气、固两相的速度、温度、压力、密度、固相容积比及熵值沿流向分布情况。文章对气、固两相参数在松弛区中的变化规律进行了讨论。     

基于石墨烯的光纤湿度传感研究

将还原氧化石墨烯(r GO)沉积在侧边抛磨光纤(SPF)上制作了一种新型的光纤湿度传感器。在高湿度区域[相对温度(RH)为70%~95%],传感器的光功率变化达到6.9 d B,尤其在RH为75%~95%区域,传感器对湿度变化能实现相关系数为98.2%的线性响应,灵敏度可达0.31 d B/(%RH),响应速度快于0.13(%RH)/s,并且具有很好的可重复性。对传感机理的理论分析可以解释实验结果,并且表明这种基于石墨烯的光纤传感器亦可广泛应用于其他种类化学气体的探测。这种全新机理的光学传感器是对石墨烯电化学传感器的一种很好的补充,并将促进石墨烯在化学传感技术中的应用。