Grain boundary segregation and its influences on ionic conduction properties of scandia doped zirconia electrolytes

Solid oxide fuel cell is a promising energy conversion system which converts chemical energy into electrical energy directly. Electrolyte is the key component and determines the working temperature. In this paper,ceria and scandia co-doped zirconia electrolytes sintered from 1300 to 1550 ℃ were chosen as research objects. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy were performed to characterize the ceramic samples. The effects of grain size and grain boundary element segregation on the electrical conductivity were focused. Electrochemical impedance spectroscopy was used to calculate the bulk, grain boundary and specific grain boundary conductivity. Results show that the bulk and grain boundary ionic conductivity increases with the increasing grain size.However, the specific grain boundary conductivity decreases with the increasing grain size. This is explained by the fact that Sc~(3+) is segregated at the grain boundary, which leads to higher oxygen vacancy concentration when sintered at lower temperature.     

Inverted pendulum stabilization: Characterization of codimension-three triple zero bifurcation via multiple delayed proportional gains

The paper considers the problem of stabilization of systems possessing a multiple zero eigenvalue at the origin. The controller that we propose, uses multiple delayed measurements instead of derivative terms. Doing so, we increase the performances of the closed loop in presence of system uncertainties and/or noisy measurements. The problem formulation and the analysis is presented through a classical engineering problem which is the stabilization of an inverted pendulum on a cart moving horizontally. On one hand, we perform a nonlinear analysis of the center dynamics described by a three dimensional system of ordinary differential equations with a codimension-three triple zero bifurcation. On the other hand, we present the complementary stability analysis of the corresponding linear time invariant system with two delays describing the behavior around the equilibrium. The aim of this analysis is to characterize the possible local bifurcations. Finally, the proposed control scheme is numerically illustrated and discussed.     

Identification of factors that accelerate hydrogen production by Clostridium butyricum RAK25832 using casamino acids as a nitrogen source

The ability of Clostridium butyricum RAK25832 to use casamino acids as a nitrogen source was investigated. Strain RAK25832 showed the capacity to utilize different types of carbon sources. With glucose as a carbon source (10 g/L), the preferred final concentration of casamino acids was 26.67 g/L, with a cumulative hydrogen production, production rate, and yield of 2505 mL H₂/L, 160 mL/h, and 1.81 mol H₂/mol glucose, respectively. Eighteen metal elements were screened to identify the most important metals for biohydrogen production, and four elements were optimized. The optimal medium composition was MgCl₂·6H₂O (0.1 g/L), K₂HPO₄·3H₂O (6.67 g/L), NaHCO₃ (2.6 g/L), and FeCl₂·4H₂O (0.002 g/L). Vitamin supplementation of the medium showed no significant effect on hydrogen production. Under the optimized conditions, cumulative hydrogen production reached 3074 mL H₂/L. This is the first study to demonstrate the use of casamino acids as a nitrogen source by C. butyricum.     

新形势、新条件下金工实习教学改革

本文讲述了新形势、新条件下金工实习的性质、目的和教学的基本要求。分析了职教金工实习的教学现状。并从金工实习的顺序、教学模式、教学计划、教学内容等多方面讲述了如何适应新的人才培养方案,改革金工实习教学模式。如何加强教学管理,提高实习效果。最后讲述了改革金工实习教学管理模式,提高师资队伍人员素质的方法。     

广州国际会议展览中心标志系统设计

以广州国际会议展览中心标志系统的设计为例,对设计手法及理念进行了探讨,希望能对今后类似设施的设计有所启迪。     

玻璃拱下的城市--费城金慕演艺中心的室内空间

本文针对拉斐尔·维诺里设计的金慕演艺中心进行介绍,分析了建筑师把城市功能引入室内空间的设计思想,以及他在使用材料与技术上的表现主义手法。     

从读书行为到信息交流--南昌大学图文信息中心设计

本文回顾了南昌大学图文信息中心的设计过程。通过对项目背景、总图关系、功能空间形态、建筑形态等方面的介绍,探讨了当代高校图书馆的内涵和外延所发生的一些新的变化,指出了从读书行为到信息交流的转变是促使图书馆新形态产生的直接原动力。     

光的教堂与朗香教堂形态结构关联研究

本文着眼于体验视角,分析光的教堂与朗香教堂中各存在主体的构成及其相互关系、各存在主体分别对应的空间形态及其相互关系,以及这两组关系之间的关联:进而通过对朗香教堂空间形态结构的图式分析,透过形态表象的差异,揭示光的教堂在空间形态结构方面与朗香教堂的关联性;从一侧面展示当代教堂建筑形态生成的某些一般性规律。     

厦门市集美文体中心结构设计

文化体育类公共建筑不同于普通的住宅,常常会出现大跨度钢结构屋面,空旷结构等复杂的结构形式,本文通过集美文体中心结构设计的实例,对结构体系的选择、结构分析计算的难点进行了详细的论述,为此类公共建筑的设计总结出一套有效的设计分析方法。     

西安外国语学院图文信息中心方案设计

校园建筑的品质该如何定位，校园文化的内涵该如何体现，是当代校园规划与建筑设计需要认真思考的问题。该文通过对西安外国语学院新校区图文信息中心的建筑设计的诠释，把校园建筑的品质与校园文化内涵相结合，紧紧围绕中华古文化神韵的代表——“王帛”文化主题，尝试以现代的建筑语言从总体布局和建筑造型上再现中华灿烂的传统文化精神，提出了积极创建富于人文内涵的现代校园建筑设计方法和理念。