基于循环经济理论的北京市建筑固体废物再利用模式研究

本文基于循环经济理论的三重循环,在分析北京市建筑固体废物再利用现状的基础上,介绍了建筑行业内层面、行业间层面和社会层面的固体废物再利用的方法,最终提出了基于循环经济的北京市建筑固体废物再利用体系,为北京市的建筑固体废物再利用提供了参考.     

Determination of Diffusion Coefficient and Analysis of Diffusion Factors of Cr（Ⅵ） Ion in Clay Soil

Some laboratory diffusion tests were conducted with diffusion device to determine the diffusion coefficient of Cr(Ⅵ) ion passing through Dalian red clay samples. The concentrations of Cr(Ⅵ) at different places of the samples were then measured spectrophotometrically after a standing time of 1 000 d. A one-dimensional solute transport equation was used to simulate the transport of Cr(Ⅵ) through clay samples. Back-calculation of diffusion coefficient of Cr(Ⅵ) was made with finite difference method. Parametric analysis was conducted to simulate variations in soil dry density, temperature, pH and standing time. The results show that the method used in this paper is simple and effective. The diffusion coefficient of Cr(Ⅵ) in Dalian red clay varies from 1.50×10-7 cm2/s to 2.08×10-7 cm2/s. After 1 000 d diffusion, the concentration of the source solution drops down to 1.27 mg/L from 62.5 mg/L, and the diffusion distance is only 3.5 cm. Under the assumption that diffusion coefficient is constant, the diffusion effect becomes more obvious with lower density, lower temperature, higher pH value, and much more time.     

Numerical Simulation of Unsteady-State Flowsin Bubble Column Reactors

Thebubblecolumnreactor (BCR) ,withbatchfeedandcontinuousgasaerated ,hasobtainedwideapplica tionsinbiochemicalengineering ,chemicalengineeringandwastewatertreatment ,etc .OneimportantfeatureofBCRisthattheconversionandtheyieldofthereactioncanbehighlyincreasedundertheunsteady stateopera tion .Sincethemassandtheheattransferpropertiesinaprocessmainlydependontheflowbehavior ,itisstronglydesirabletoinvestigatetheunsteady stateflowstructurebeforethedesignandscale upofBCRwithhighreactiveconversionsa…     

论化工本科专业国际认证与国内认证的“实质等效”性

本文介绍了天津大学化学工程与工艺本科专业开展英国化学工程师学会(简称IChemE)国际认证和中国工程教育认证协会(简称认证协会)国内认证多年的实践过程,从专业认证的标准、课程体系要求、自评报告的撰写、认证的程序等多方面进行了比较和解读,深入探讨和分析了国际认证与国内认证的"实质等效"性。表明我国的工程教育认证工作,已经与国际认证体系接轨,二者具有"实质等效"性。     

基于核心素养的高中数学概念课教学——以“角的概念的推广”为例

笔者以“角的概念的推广”一课为例,采用问题驱动式教学,借助一个个数学问题引导学习活动的开展,在问题的解决过程中发展学生的思维,实现学生数学核心素养的提升。