该工作制备了F离子掺杂的SrFeFxO3-x-δ(SFFx,x=0、0.125、0.25)阴极材料,研究了F离子掺杂对材料结构及电化学性能的影响。结果表明,F离子的引入可使材料在室温下保持立方结构,F离子掺杂显著提高SFFx的电子电导率、降低材料的热膨胀系...该工作制备了F离子掺杂的SrFeFxO3-x-δ(SFFx,x=0、0.125、0.25)阴极材料,研究了F离子掺杂对材料结构及电化学性能的影响。结果表明,F离子的引入可使材料在室温下保持立方结构,F离子掺杂显著提高SFFx的电子电导率、降低材料的热膨胀系数、提高材料的氧表面交换系数和体扩散系数,降低电极反应的极化电阻,改善材料的电化学催化特性。电极反应动力学过程研究表明,F掺杂可显著促进氧分子的解离过程,以SFFx与Sm0.2Ce0.8O2-δ(物质的量比1:1)的混合材料为复合阴极,以La0.9Sr0.1Ga0.8Mg0.2O3-δ(300μm)为电解质并作为支撑体,NiO-Gd0.1Ce0.9O2-δ为阳极组装单电池。研究发现,F掺杂提高了电池的功率密度,当x=0.25时,700 o C和850oC时最大功率密度分别可达446和962 mW·cm-2。展开更多
To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used a...To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used as a case study to illustrate the process of joint reaction analysis. The substructure synthesis method is applied to deriving an analytical elastodynamic model for the 3-PRS PKM device, in which the compliances of limbs and joints are considered. Each limb assembly is modeled as a spatial beam with non-uniform cross-section supported by lumped virtual springs at the centers of revolute and spherical joints. By introducing the deformation compatibility conditions between the limbs and the platform, the governing equations of motion of the system are obtained. After degenerating the governing equations into quasi-static equations, the effects of the gravity on system deflections and joint reactions are investigated with the purpose of providing useful information for the kinematic calibration and component strength calculations as well as structural optimizations of the 3-PRS PKM module. The simulation results indicate that the elastic deformation of the moving platform in the direction of gravity caused by gravity is quite large and cannot be ignored. Meanwhile, the distributions of joint reactions are axisymmetric and position-dependent. It is worthy to note that the proposed elastodynamic modeling method combines the benefits of accuracy of finite element method and concision of analytical method so that it can be used to predict the stiffness characteristics and joint reactions of a PKM throughout its entire workspace in a quick and accurate manner. Moreover, the present model can also be easily applied to evaluating the overall rigidity performance as well as statics of other PKMs with high efficiency after minor modifications.展开更多
文摘该工作制备了F离子掺杂的SrFeFxO3-x-δ(SFFx,x=0、0.125、0.25)阴极材料,研究了F离子掺杂对材料结构及电化学性能的影响。结果表明,F离子的引入可使材料在室温下保持立方结构,F离子掺杂显著提高SFFx的电子电导率、降低材料的热膨胀系数、提高材料的氧表面交换系数和体扩散系数,降低电极反应的极化电阻,改善材料的电化学催化特性。电极反应动力学过程研究表明,F掺杂可显著促进氧分子的解离过程,以SFFx与Sm0.2Ce0.8O2-δ(物质的量比1:1)的混合材料为复合阴极,以La0.9Sr0.1Ga0.8Mg0.2O3-δ(300μm)为电解质并作为支撑体,NiO-Gd0.1Ce0.9O2-δ为阳极组装单电池。研究发现,F掺杂提高了电池的功率密度,当x=0.25时,700 o C和850oC时最大功率密度分别可达446和962 mW·cm-2。
基金Project(Kfkt2013-12)supported by Open Research Fund of Key Laboratory of High Performance Complex Manufacturing of Central South University,ChinaProject(2014002)supported by the Open Fund of Shanghai Key Laboratory of Digital Manufacture for Thin-walled Structures,ChinaProject(51375013)supported by the National Natural Science Foundation of China
文摘To gain a thorough understanding of the load state of parallel kinematic machines(PKMs), a methodology of elastodynamic modeling and joint reaction prediction is proposed. For this purpose, a Sprint Z3 model is used as a case study to illustrate the process of joint reaction analysis. The substructure synthesis method is applied to deriving an analytical elastodynamic model for the 3-PRS PKM device, in which the compliances of limbs and joints are considered. Each limb assembly is modeled as a spatial beam with non-uniform cross-section supported by lumped virtual springs at the centers of revolute and spherical joints. By introducing the deformation compatibility conditions between the limbs and the platform, the governing equations of motion of the system are obtained. After degenerating the governing equations into quasi-static equations, the effects of the gravity on system deflections and joint reactions are investigated with the purpose of providing useful information for the kinematic calibration and component strength calculations as well as structural optimizations of the 3-PRS PKM module. The simulation results indicate that the elastic deformation of the moving platform in the direction of gravity caused by gravity is quite large and cannot be ignored. Meanwhile, the distributions of joint reactions are axisymmetric and position-dependent. It is worthy to note that the proposed elastodynamic modeling method combines the benefits of accuracy of finite element method and concision of analytical method so that it can be used to predict the stiffness characteristics and joint reactions of a PKM throughout its entire workspace in a quick and accurate manner. Moreover, the present model can also be easily applied to evaluating the overall rigidity performance as well as statics of other PKMs with high efficiency after minor modifications.
