离子交换纤维微观形貌特点及结构修饰研究

利用比表面积测试仪、扫描电子显微镜等物理化学方法对颗粒与纤维状离子交换剂的链间交联与微观形貌进行了研究,通过刚性交联剂对聚丙烯-苯乙烯-二乙烯基苯(PP-ST-DVB)离子交换纤维骨架结构进行了修饰改造。结果表明:离子交换纤维由于不能通过交联剂与致孔剂参与下的单体聚合构建具有丰富微孔的高分子骨架,所以不存在丰富孔结构和高比表面积特征,其内部为连续凝胶相结构;外比表面积大、传质距离短、交联键分布均匀是其反应动力学和渗透压稳定性能优异的主要原因;刚性交联剂在PP-ST-DVB纤维上的附加交联反应使其比表面积从原来的0.5 m~2/g提高到200 m~2/g以上,附加交联反应所形成的分子尺度微孔孔径分布窄,具有超高交联树脂的结构特点。     

酯化法合成丙酮酸乙酯的研究

论述了以丙酮酸、乙醇为原料,离子交换树脂作催化剂,催化合成丙酮酸乙酯的新工艺。考察了催化剂种类、用量、原料配比、反应时间以及催化剂使用次数等因素对酯化率的影响,确定了催化剂种类和最佳工艺条件。结果表明,732强酸性离子交换树脂具有良好的催化活性和选择性,可多次重复使用,酯化率可达85.7%,产品质量符合国家标准。     

挤出机双流道筒体的设计及换热能力的计算与分析

介绍了设计双流道筒体的必要性,通过建立物理、数学模型详细论述了双流道筒体的设计原理及换热计算过程,并通过试验对比分析验证了模型的可靠性,同时对单、双流道筒体的换热能力进行对比分析,得出了可靠的结论.     

Seeker optimization algorithm for global optimization: A case study on optimal modelling of proton exchange membrane fuel cell (PEMFC)

In order to optimize the proton exchange membrane fuel cell (PEMFC) model parameters, a novel approach based on seeker optimization algorithm (SOA) is proposed. The SOA is based on the concept of simulating human searching behaviors, where the choice of search direction is based on the empirical gradient by evaluating the response to the position changes and the decision of step length is based on uncertainty reasoning by using a simple Fuzzy rule. In this study, after evaluated on benchmark function optimization, the SOA is applied to optimal modelling of the PEMFC by using a fuel cell test system in Fuel Cell Application Centre (FAC) at the Temasek Polytechnic, and compared with several state-of-the-art versions of differential evolution (DE) and particle swarm optimization (PSO) algorithms. The simulation results show that the proposed approach is superior to other compared algorithms, and the PEMFC model with optimized parameters by SOA fitted experimental data well. Hence, SOA is an effective and reliable technique for optimizing the parameters of PEMFC model, and can be helpful for system analysis, optimization design and real-time control of the PEMFCs.     

配电自动化主站系统建设方案分析

结合某城市智能电网配电自动化试点建设,介绍配电自动化主站系统的建设原则和可实现的功能,提出软硬件平台的具体设计和配置,以及使用信息交换总线技术实现配电自动化系统与相关系统交互的方案,并对建设方案的可行性进行了分析。     

氢能发电机移相全桥零电压PWM DC/DC变换器研究

介绍了移相全桥零电压PWM软开关电路的组成、工作原理及软开关的工作过程,阐述了超前桥臂和滞后桥臂的实现条件,依据能量交换守恒原理对电感和电容的选择进行了探讨,并对PWM软开关电路特有的占空比丢失现象进行了分析,仿真验证了适应于质子交换膜燃料电池发电机输出特性的移相全桥零电压PWM软开关电路的合理性。     

防爆型水冷电机内换热与温度场计算

采煤机电机安装空间严格受限,随着电机设计容量的提升,使单位体积损耗(发热率)增大.为了研究该类电机的发热与冷却问题,在对防爆型水冷电机的结构、材料以及换热机理进行分析的基础上,建立了防爆型水冷电机的传热数学物理模型.采用有限元法对电机定、转子及水套的温度场进行了计算与分析.通过计算结果与实测值对比,验证所建传热模型可以真实反映实际传热过程.分析计算结果表明电机定子最高温度点位于定子上层绕组近气隙侧;定子齿是热量传递的主要通道,热流密度最大;选用适当的冷却水流速,可以用最小的代价获取所需的冷却效果.研究结果可以为采煤机电机热控制和优化设计提供理论依据.     

电子数据交换EDI

介绍了电子数据交换的概念、EDI系统的组成，阐述了传统交易模式与EDl交易模式的区别，分析了实现EDI的三项挂心技术，介绍了EDl与Internet的关系、实施EDI的效益以及EDI的应用与EDI的前景。     

XML在机械CAD系统中的应用

分析了Internet上最新的XML技术的特点，通过实例用XML技术对机械CAD产生的各种文档信息进行了描述，并且构造了基于XML文档交换的分布式支持环境的体系结构。     

Oxygen Surface Exchange at Grain Boundaries of Oxide Ion Conductors

The role of grain boundaries on oxygen surface exchange in an oxide ion conductor is reported. Atomic‐scale characterization of the microstructure and chemical composition near the grain boundaries of gadolinia‐doped ceria (GDC) thin films show the segregation of dopants and oxygen vacancies along the grain boundaries using the energy dispersive spectroscopy in scanning transmission electron microscopy (STEM‐EDS). Kelvin probe microscopy is employed to verify the charge distribution near grain boundaries and shows that the grain boundary is positively charged, indicating a high concentration of oxygen vacancies. AC impedance spectroscopy on polycrystalline GDC membranes with thin interfacial layers with different grain boundary densities at the cathodes demonstrated that the cells with higher grain boundary density result in lower electrode impedance and higher exchange current density. These experimental evidences clearly show that grain boundaries on the surface provide preferential reaction sites for facilitated oxygen incorporation into the GDC electrolyte.