波节式换热管压缩失稳试验研究

通过对不同材料、直径和壁厚的波节式换热管进行压缩失稳试验,绘出应力和应变强度关系曲线,指出直光管经胀管成型为波节管后,应力状态分布明显不同于光管,壁厚和直径等规格尺寸的不同会影响波纹管的强度性能.     

浅谈工程项目管理的若干问题

随着我国社会经济的发展,人们对建筑的质量要求越来越高,建筑工程项目管理的作用也越来越大,其对保证建筑工程的实施和质量有着十分重要的意义。通过分析建筑项目管理工作的作用和具体内容,提出了改善和创新的方法和措施,以供相关单位借鉴和参考。     

促进我国硫铁矿制酸的发展

我国硫磺制酸原料主要依赖进口,大量进口硫磺已经影响到世界硫磺的供需关系,硫磺价格居高不下.硫铁矿是我国自有资源,可保证长期、稳定的供应,对我国硫酸工业的稳定和安全具有重要作用,我国发展硫铁矿制酸有其必要性.硫铁矿制酸实现大型化;采用高品位硫铁矿制酸,有效利用铁资源和热能;实现清洁生产,减少废水排放、尾气二氧化硫排放及综合利用废热,是发展方向.抓住硫酸需求增加的机遇,采用先进技术发展硫铁矿制酸,硫铁矿制酸一定会有良好的发展前景.     

Synthesis and Morphology of TiO2 Nanotube Arrays by Anodic Oxidation Using Modified Glycerol-Based Electrolytes

Titanium dioxide (TiO₂) nanotube arrays were prepared by electrochemical anodization of titanium sheets in the glycerol 176 mL/H₂O 44 mL/NH₄F 0.5 wt% electrolytes modified with H₂SO₄ and NaAc addition. The surface morphologies, average inner diameter, and the length of the nanotube arrays changed with the solution pH in the range from 5.6 to 4.0 by adding H₂SO₄. A uniform surface morphology of the nanotubes with average inner diameter of ∼80 nm and a length of ∼1000 nm was obtained when the solution pH was 5.0. The growth rates of the nanotubes were remarkably enhanced by NaAc addition in the range of 0.04–0.14 M . With NaAc addition of 0.10 M , the length of the nanotube arrays reached 4.16 μm after an 8-h anodization, increasing 3.23 μm compared with no NaAc addition. The relationship between solution pH and growth of TiO₂ nanotubes was analyzed by current–time curves, solution electrical conductivities, and scanning electron microscopy (SEM), and the role of NaAc was also discussed based on SEM and solution electrical conductivities.     

Carbon molecular sieve films produced by dc sputtering

This paper reports adsorption measurements that show molecular sieve effects in amorphous hydrogenated carbon (a-C : H) films deposited by d.c. magnetron discharge decomposition of acetylene. Adsorption of organic gases on the films is studied by using a quartz crystal microbalance technique. The sieve effect in this material depends on both deposition and annealing conditions. Films having significant molecular sieve effects are found to be typically microporous and to have a very small characteristic micropore dimension. It is suggested that the d.c. sputtered a-C : H film may be useful as a molecular sieve material in selective adsorption and gas permeation studies.     

Oxidative dehydrogenation of ethane over Co–BaCO3 catalysts using CO2 as oxidant: effects of Co promoter

Co–BaCO₃ catalysts exhibited high catalytic performance for oxidative dehydrogenation of ethane (ODE) using CO₂ as oxidant. The maximal formation rate of C₂H₄ was 0.264 mmol · min⁻¹ · (g · cat.)⁻¹ (48.0% C₂H₆ conversion, 92.2% C₂H₄ selectivity, 44.3% C₂H₄ yield) on 7 wt% Co–BaCO₃ catalyst at 650 °C and 6000 ml. (g · cat.)⁻¹. h⁻¹. Co–BaCO₃ catalysts were comparatively characterized by XRF, N₂ isotherm adsorption-desorption, XRD, H₂-TPR and LRs. It was found that Co⁴⁺–O species were active sites on these catalysts in ODE with CO₂. The redox cycle of Co–O species played an important role on the catalytic performance of Co–BaCO₃ catalysts. On the other hand, the co-operation of BaCO₃ and BaCoO₃ was considered to be one of possible reasons for the high catalytic activity of these catalysts.     

策应鄱阳湖生态经济区建设 推动吉安进位赶超绿色崛起

建设鄱阳湖生态经济区是国家从战略全局和长远发展出发作出的一项重大决策。如何主动策应鄱阳湖生态经济区建设,推动吉安进位赶超、跨越发展,是摆在我们各级政府和科技部门面前一项亟待解决的问题。为此,一是要提高认识,统一思想,切实增强策应规划的使命感和责任感;二是要结合实际,突出重点,全面对接鄱阳湖生态经济区规划;三是要加强领导,落实措施,确保吉安进位赶超、绿色崛起取得明显成效。     

确定土壤背景值的Hazen概率法——以铜陵矿区Pb为例

本文选取已知土壤背景含量的铜陵矿区,基于Hazen概率曲线,探讨了土壤污染重金属元素Pb背景含量与污染叠加含量的区分方法.得到Pb元素的背景含量为28.5μg/g,与该区深层土壤样中Pb元素含量的平均值(34μg/g)比较接近.还得到了Pb元素污染叠加含量与背景含量的界线点51μg/g.基于Hazen概率曲线区分铜陵矿区土壤Pb元素背景含量与污染叠加含量的方法是有效的,有必要将该方法推广到土壤中其它重金属污染元素、其它地区作进一步研究.     

高校广告学课程教学模式改革探讨

广告行业的繁荣,使得广告业成为当今社会炙手可热的行业之一,各地高校争相开办广告类专业或开设广告学课程.作者分析了目前高校广告学课程教学的现状,指出高校广告学课程教学中存在的不合理因素,并提出了改革建议,旨在适应市场经济发展的需要,创建具有特色的广告学课程教学新模式.     

永磁同步电机伺服控制系统设计

根据永磁同步电机的特点,研究、开发了数字信号处理器(DSP)和可编程逻辑器件(CPLD)控制的数字伺服系统,并进行了电流环、转速环和位置环的闭环实验.实验结果表明,该系统无论在调速比、定位时间、定位精度和抗干扰能力等性能指标上都已达到高性能伺服系统的一般要求.