Three-dimensional CFD modeling of transport phenomena in anode-supported planar SOFCs

In this study, a three-dimensional computational fluid dynamics model has been developed for an anode-supported planar SOFC. The conservation equations of mass, momentum, species/charges and thermal energy are solved by finite volume method for a complete unit cell consisting of 13 parallel channels in both anode and cathode. The simulation results of the developed model are well in agreement with the experimental data obtained at same conditions. In this study, the co-flow arrangement with hydrogen utilization of 60 % and operating voltage of 0.7 V is used as the base case, and compared with the counter-flow arrangement. The predicted results reveals that the maximum temperature obtained in the counter-flow arrangement is about 10 °C lower than that of co-flow, but the counter-flow arrangement has a higher temperature gradient between the respective anodes and cathodes in a cross-section normal to the main flow direction, especially in the air inlet region of the cell (x = 0.04 m),which is very harmful to the lifetime of materials. The current density is very unevenly distributed along and normal to the flow direction for both the co- and counter-flow arrangements, and the maximum values occur at junctions of the electrodes, channels and ribs, which causes higher over-potentials and ohmic heating.     

纳米材料电化学与生物传感器——有机微污染物检测新途径

本文介绍了近年来纳米材料电化学与生物传感器在有机微污染物检测中的研究现状,分析了这些传感器中纳米材料修饰电极的特点,重点阐述了纳米材料在有机微污染物检测中的重要作用,列举了一些纳米材料电化学与生物传感器在有机微污染物检测中的应用。最后对纳米材料电化学与生物传感器用于有机微污染物的检测研究进行了简要评述和展望。     

Fluorinated star‐shaped block copolymers: Synthesis and optical properties

Tetrakis(4‐(1‐bromoethyl)phenyl)silane is synthesized and utilized to initiate the atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) to generate bromo‐terminated four‐armed PMMA macroinitiators, which further initiate the ATRP of methylacryloyloxyl‐2‐hydroxypropyl perfluorooctanoate (FGOA) to create fluorinated star‐shaped block copolymers PMMA‐b‐poly(FGOA)s with fluorine content ranging from 0 to 31.7 wt %. The polymerizations are well controlled with the polydispersity indices <1.30. The polymers readily dissolve in common organic solvents and show good film‐formation. Compared with the nonfluorinated sample, the fluorinated films exhibit significantly increased water contact angles owing to the enrichment of fluorine on the surface. The enhanced hydrophobicity is advantageous for the optical stability when the devices work under a moist environment. Moreover, the films possess high thermo‐optic coefficients, tunable refractive indices, and extremely low birefringence coefficients because of the presence of bulky and rigid tetraphenylsilane core and star‐shaped topological structure, showing potential application in optical waveguide devices. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1969–1977     

Synthesis and fluorescence properties of dysprosium‐coordinated with high‐Tg polyaryletherketones containing carboxyl side groups

A series of novel dysprosium coordination polymers were synthesized using new high‐T_g carboxyl‐containing polyaryletherketones (PEKs) as macromolecular ligands and a small molecule, 1,10‐phenanthroline, as co‐ligand. The FTIR, WAXD, and UV–Vis results indicated that the dysprosium ions were coordinated simultaneously with carboxyl group of PEKs and 1,10‐phenanthroline, and homogeneously distributed along the polymer backbone. These obtained dysprosium coordination polymers showed excellent film‐formation properties. Moreover, all the dysprosium coordination polymers could exhibit the intense characteristic emission of dysprosium ions under UV excitation. Meanwhile, the emission intensity increased with increasing dysprosium ion content, and no obvious fluorescence quenching happened at the Dy³⁺ ion content up to 10.71 wt%, which was attributed to the very rigid structure of PEK and synergistic coordination effect of PEK and 1,10‐phenanthroline. Copyright © 2009 John Wiley & Sons, Ltd.     

THEORETICAL AND EXPERIMENTALRESEARCH ON DYNAMIC BEHAVIOR OF GUYED MASTS UNDER WIND LOAD

I. INTRODUCTION Wind-induced vibration is the critical factor for the safety of guyed masts. Many dynamic modelshave been proposed in the literature[1 , 2]. However, there are obvious de?ciencies in many of theseprevious works owing to the poor cabl…     

一种高速插秧机作业面积自动测量系统设计

为实现对插秧机作业区域和作业边界的自动识别以及作业面积的实时自动测量,根据GPS定位信息采集、作业区域及边界的自动识别算法以及作业面积自动求算算法展开研究,并通过VisualBasic.NET2010设计了一种基于STC单片机和GPS定位技术的高速插秧机作业面积测量系统;同时系统设计中对各个硬件模块结构进行了优化,并完成了在C语言环境中驱动程序的编写工作,该系统在机械作业时,通过对GPS定位轨迹信息的分析处理后,能够自动计算机械动态作业面积;试验结果表明:该系统能够完成对工作时间、工作地点和作业面积等相关信息的实时记录的要求,并能完成不规则图形面积测量工作,数据共享度大,价格低廉,且相对误差可达1.25%左右,能适合其它各种农业机械完成对作业面积的测量,一定程度上为精细农业的发展提供了依据。     

A new method and instrument for accurately measuring interval between ultrashort pulses

Using second-order autocorrelation conception, a novel method and instrument for accurately measuring interval between two linearly polarized ultrashort pulses with real time were presented. The experiment demonstrated that the measuring method and instrument were simple and accurate (the measurement error ＜ 5 fs). During measuring, there was no moving element resulting in dynamic measurement error.     

应用电容层析成象和压差对比法对流化床内固体颗粒浓度分布的测量研究

本文报告了一种可以用于对流化床内固体浓度分布测量的电容层析成象技术。应用这一技术的测量结果,与目前常用的压差法测量结果进行了对比。对在鼓泡流化床的测量结果,二者吻合较好,偏差在８．５％以内;随着流化速度增加,二种测量结果的差距逐渐增加,偏差最大值产生在腾涌流化状态。本文分析了造成偏差的原因,并对二种测量方法的特性进行了讨论。     

鲹科模式中前体对尾鳍推进影响的数值研究

自然界中鱼类尾鳍形状各种各样,但前体大部分都是扁平的椭圆形状.该文研究了不同形状的前体对尾鳍推进的影响.尾鳍统一采用月牙形状;前体采用了两种模型:A-鱼类扁平椭圆形状和B-潜艇水滴回转体形状.通过以Strouhal数为控制参数的FLUENT数值模拟,发现前体形状对于尾鳍的静止状态和运动状态有不同的作用,采用模型A的前体形状更有利于长时间巡游,故鱼类采用模型A这种前体形状是自然界优胜劣汰的进化必然选择.     

双官能团液体脂环族环氧化合物的合成与性能

脂环族烯烃类化合物经过环氧化反应制备了三种液体脂环族环氧化合物 ,即 3,4 环氧环己基甲基 2′ ,3′ 环氧环己醚 (Ⅰe ) ,双 (2 ,3 环氧环己基 )醚 (Ⅱe )和双 (2 ,3 环氧环己烷 ) (Ⅲe ) .反应收率大于 80 % .用红外光谱、核磁共振谱、元素分析、环氧当量测定等方法证实了它们的结构 .三种环氧化合物在固化前都具有很低的粘度 (<10 0mPa·s ,2 5℃ ) ,用酸酐类固化剂热固化后得到的交联聚合物具有高的玻璃化转变温度 (Tg=15 0～ 180℃ )、低的线性热膨胀系数 (α1 =6 .0× 10 - 5 ～ 7.6× 10 - 5 ℃ ,α2 =14.5× 10 - 5 ～ 17.0× 10 - 5 ℃ )和较高的储存模量 (E′1 =2 .1～ 3.0GPa ,E′2 =0 .0 2 0～ 0 .0 33GPa) ,它们的总体性能好于国外同类产品ERL 42 2 1.在涂料、电子封装料等方面具有良好的应用前景