辐射化学基础理论研究现状 Ⅰ.初级辐解产物

本文着重于辐射作用于物质最初生成的产物,包括激发态的离子与分子,能量超过热能的次级电子等的反应以及电荷和激发能的转移,并试图论述它们的最新发展。     

浅谈中等职业学校计算机基础教学

当今社会对中职学校毕业生的计算机应用能力要求越来越高,计算机技术水平的高低以及计算机应用能力的强弱,已经成为今天衡量中职学校毕业生质量和水平的重要尺度之一。而目前计算机基础教学存在教学内容过分单一、教学手段落后等弊端,为了解决这些问题,汲取多年计算机基础教学的实践经验,针对新形式下计算机基础课程的课程体系、教学内容和教学方法的改革进行了探讨。     

浅谈在AutoCAD环境下的“母线”提取应用

随着AutoCAD在地形图中的应用,对其进行了二次开发,使其能方便的用于制图,有很多开发者喜欢用"块线型"来表示一些线状地物。作者通过自己分析AutoCAD三种不同类型的"母线"存放方式,总结出统一的"母线"提取办法。避免重新数字化的麻烦,大大的减少了工作量,节省了宝贵的时间,方便了作图,提高了工作效率。     

LX—2型变频式喂线设备的研制及应用

根据炼钢生产的实际需要,分析了喂线技术的工艺要求,介绍了所研制的LX－2型变频式喂线机的结构特点,指出了影响喂线机使用效果的因素,并提出了若干措施。     

9SiCr钢中的筐篮编结状马氏体及其性能

将9SiCr钢的粒状原始组织改变为片状,再经830℃淬火后,其马氏体形态为筐篮编结状。而传统工艺所获得的马氏体形态为针状.这种筐篮编结状马氏体是9SiCr钢中一种崭新的组织形态,其精细结构为平行成束的板条。亚结构为高密度缠结位错.它有良好的综合机械性能,强韧性高,耐磨性高。     

Estimation in Random Coefficient Autoregressive Models

Abstract. We propose the quasi‐maximum likelihood method to estimate the parameters of an RCA(1) process, i.e. a random coefficient autoregressive time series of order 1. The strong consistency and the asymptotic normality of the estimators are derived under optimal conditions.     

BAF+混凝沉淀工艺用于二级出水回用研究

针对沈阳北部污水处理厂二级出水回用处理进行中试规模的试验研究,试验结果表明:曝气生物滤池(BAF) 高效混凝沉淀池组合工艺能全面净化原水的水质,在气水比3∶1,水力负荷为1.25 m3/m2.h条件下,对氨氮、CODC r的平均去除率分别达到92.35%,41%;对SS和Tp的去除率分别达到89.82%,42.74%。     

Crystallization of calcium sulphate hemihydrate in concentrated phosphoric acid solutions

We aim to show the existence of agglomeration by measuring and modelling secondary nucleation and crystal growth rates of calcium sulphate hemihydrate, CaSO₄-0.5 H₂O, in concentrated phosphoric acid solutions. Using a batch crystallizer we measured the evolution of the population density as a function of supersaturation, H₂SO₄ excess and stirring rates. All experiments were carried out at 90 °C in solutions at 40 wt.% of P₂O₅, simulating the usual conditions for crystallizing hemihydrate in the industrial processes of phosphoric acid production. Nucleation and growth rates were calculated from the population number densities, using the moments analysis method. A model is presented for describing the crystallization process of hemihydrate. It is shown that secondary nucleation and growth rates are quadratic functions of supersaturation. H₂SO₄ concentrations affect supersaturation but at the same supersaturation the growth rates are not significantly different. Nucleation is independent of the stirring rate, whereas growth rates are slightly affected for stirring rates up to 500 rpm. Taking agglomeration into account, the moments method fits very well the experimental data.     

炉外精炼用耐火材料提高寿命的途径及其发展动向

结合VOD与RH介绍了造成炉外精炼蚀损严重部位的原因。从MgO-Cr2O3、MgO-CaO、MgO-C、MgO-CaO-C、MgO-MgO·Al2O3等耐火材料性能及在精炼中的作用介绍了如何选择耐火材质;从接触角、熔渣粘度、形成高熔点化合物、气孔微细化以及炉渣成分控制、双饱和与精炼温度等方面介绍了提高炉外精炼用耐火材料寿命的途径。最后结合镁铬、镁钙、MgO-C、镁钙碳与无铬耐火材料介绍了炉外精炼用耐火材料的发展动向,并对MgAlON结合镁质耐火材料在炉外精炼中的研究与应用进行了评估与预期。     

CFD SIMULATION OF THE GAS-SOLID FLOW IN THE RISER OF A CIRCULATING FLUIDIZED BED WITH SECONDARY AIR INJECTION

A comprehensive investigation was carried out to study hydrodynamics aspects of secondary air injection in circulating fluidized beds. This article presents modeling and results of computational fluid dynamics simulations of gas-solid flow in the riser section of a laboratory-scale (ID = 0.23 m, height = 7.6 m) circulating fluidized bed with a radial secondary air injector. The gas-solid flow model is based on the two-fluid (Eulerian-Eulerian) approach, where both gas and solids phases are treated as interpenetrating continua. A granular kinetic theory model is used to describe the solids phase stresses. The simulation results are compared with measured pressure drop and axial particle velocity profiles; reasonable agreement is obtained. Qualitatively, excellent agreement is obtained in predicting the increase in solids volume fraction below secondary air ports, the accumulation of solids around the center of the riser due to momentum of secondary air jets, and the absence of the solids down-flow near the wall above the secondary air injection ports, which are the prominent features of secondary air injection observed in the experiments.