Influence of the preparation conditions on the properties of gold catalysts for the oxidation of glucose

In this work, two deposition–precipitation methods for the preparation of gold catalysts for glucose oxidation were investigated. Thus far, gold colloids immobilized on carbon have been used for catalytic glucose oxidation, but the long-term stability of these systems was not sufficient. To improve the long-term stability we used the deposition–precipitation methods using NaOH (DP NaOH) or urea (DP urea) as precipitation agents as they were described by Haruta and Dekkers, respectively, using alumina as a support material. With these methods, it was possible to prepare highly active and selective catalysts which showed an excellent long-term stability. DP urea was found to be the preferred method, because in contrast to DP NaOH, no losses of gold occurred during the preparation, and it was possible to adjust various gold contents up to 10 wt% Au.     

PROFIBUS-DP智能从站在开关磁阻电机控制中的应用

简要介绍PROFIBUS -DP现场总线和开关磁阻电机调速系统 (SRD) ,为了实现SRD的远程监控 ,把PROFIBUS -DP智能从站技术引入开关磁阻电机调速系统中。针对SRD具有显著的非线性 ,系统采用模糊自适应整定PID控制算法 ,并且讨论了其软、硬件的实现方法。实验证明 ,所设计的SRD系统具有良好的动、静态性能     

PLC及总线在六联装杀菌釜中的应用

针对于六联装杀菌釜共用一套热水系统的特点,以降低成本和提高生产效率,增强系统稳定性为目的,基于西门子PLC-S7300可编程控制器,利用程序设计功能块化的形式,实现更换产品程序修改,以一改六,节约时间,减少故障率,并应用总线技术,最终实现降低成本和集中控制、远程监控。     

Non-isothermal thermomechanical metallurgical model and its application to welding simulations

Abstract

This paper presents a thermomechanical metallurgical macroscopic model for steels. The model is based on an existing model that is extended for non-isothermal behaviour in combination with phase transformations. The model and its numerical implementation in ABAQUS are described using vector notation for stress and strain tensors. Model parameters are presented for the dual phase steel DP600 and the structural steel S355. For DP600, thermomechanical model parameters, i.e. hardening and strain rate dependency, have been obtained by fitting temperature and strain rate dependent tensile tests. A metallurgical model was implemented using data obtained from phase field models for the austenite growth and continuous cooling transition diagrams for phase transformations from austenite to low temperature phases. The model is applied to welding simulations of DP600 overlap joints and S355 T joints. The final distortion is compared to experiments and it is shown that the model presented is able to reproduce the experimental results very well.     

A unified dual‐primal finite element tearing and interconnecting approach for incompressible Stokes equations

A unified framework of dual‐primal finite element tearing and interconnecting (FETI‐DP) algorithms is proposed for solving the system of linear equations arising from the mixed finite element approximation of incompressible Stokes equations. A distinctive feature of this framework is that it allows using both continuous and discontinuous pressures in the algorithm, whereas previous FETI‐DP methods only apply to discontinuous pressures. A preconditioned conjugate gradient method is used in the algorithm with either a lumped or a Dirichlet preconditioner, and scalable convergence rates are proved. This framework is also used to describe several previously developed FETI‐DP algorithms and greatly simplifies their analysis. Numerical experiments of solving a two‐dimensional incompressible Stokes problem demonstrate the performances of the discussed FETI‐DP algorithms represented under the same framework.Copyright © 2012 John Wiley & Sons, Ltd.     

PROFIBUS-DP现场总线数据链路层分析

简要介绍了目前PROFIBUS规范的发展现状,给出了该文分析用到的几个PROFIBUS专用名词,提供了PROFIBUS数据链路层有穷状态机的状态转换图及其具体的状态转换分析,其对PROFIBUS主站开发具有较大的参考价值和指导意义.     

鄂坪水电站长期优化调度研究

针对鄂坪水电站的长期优化调度问题,建立了考虑保证出力发电量最大和不考虑保证出力发电量最大两种求解模型,用动态规划法进行了计算,并对两种模型下的发电量、水位过程和出力过程进行了比较分析.     

Expression of recombinant Thermomonospora fusca xylanase A in Pichia pastoris and xylooligosaccharides released from xylans by it

The mature peptide of Thermomonospora fusca xylanase A (TfxA) was successfully expressed in Pichia pastoris under the control of AOX1 promoter. The activity of recombinant T. fusca xylanase A (reTfxA) in culture supernatant was 117.3 ± 2.4 U/mg, which is 3 times higher than that of the native TfxA. The optimal temperature and pH for reTfxA were 60 °C and 6.0, respectively. When treated at 70 °C and pH 6.0 for 2 min, the residual activity of the reTfxA was 70%. The reTfxA was very stable over a wide pH range (5.0–9.0). After incubation over pH 5.0–9.0 at 25 °C for 1 h, all the residual activity of reTfxA was over 80%. The K_m and k_cat values for reTfxA were 2.45 mg/ml and 139 s⁻¹, respectively. HPLC analysis revealed that xylobiose (X2) was the main hydrolysis product released from birchwood xylan and wheat bran insoluble xylan by reTfxA. Hydrolysis results of xylooligosaccharides showed that reTfxA was an endo-acting xylanase and xylobiose, xylotriose (X3), xylotetraose (X4), xylopentaose (X5), and xylohexaose (X6) could be hydrolysed. This is the first report on the expression of reTfxA in yeast and on the determining and quantifying of the hydrolysis products released from xylans and xylooligosaccharides by reTfxA.     

西门子PLC在自动板坯火焰切割机中的应用

介绍了西门子PLC在柳钢中板厂自动板坯火切机的应用。     

分布式计算机监控系统在赵山渡引水工程中的设计

针对赵山渡引水工程原闸坝监控系统的各种缺陷,将系统结构改为分布式计算机监控系统,对硬件实现PLC对闸门的一对一控制,对软件采用软硬件控制相结合的方式,并通过比较上游来水量与下泄流量之间的数量关系来自动控制闸门的开度,实现了水闸的自动化控制和远程控制,提高了系统的可靠性,降低了系统集中控制的风险。