A Comparative study of organic fouling in hollow fiber and spiral wound membranes

The occurrence of flux decline in brackish water reverse osmosis (RO) plants due to dissolved organics is a topic of ongoing research. This type of organic fouling has also been found in seawater RO plants. A study was undertaken to compare organic fouling in hollow fiber and spiral wound membranes using a seawater feed that possessed a high concentration of huraic acid. This study was undertaken at an RO plant on Grand Cayman Island, British West Indies. The feed water came from a sea well and possessed a concentration of humic acid that varied between 35 and 60 mg/l.The hollow fiber membrane was operated at a recovery of 25% while the recovery with the spiral wound membrane varied between 5 and 25%. The performance data which included permeate flow, salt rejection, pressure drops across the membrane and analysis of the membranes for organic fouling were undertaken. This study compared the performance data and organic fouling between the hollow fiber and spiral wound meembranes.     

活化煤矸石细粉-水泥复合胶凝材料水化性能研究

主要采用XRD、DTA/TG、SEM、MIP及等温微量量热仪研究了华新硅酸盐水泥以及掺有活化煤矸石细粉水泥胶凝体体系的水化性能和微观结构,试验证明煅烧后的煤矸石具有火山灰活性。掺有活化煤矸石细粉的水泥浆体结构较疏松,孔隙较多,但随着龄期的增长,浆体结构变得越来紧密,其主要的水化产物亦为水化硅酸钙凝胶、钙矾石和Ca(OH)2晶体。     

基于数据结构化的三维动画压缩方法研究

在三维动画应用日益广泛的背景下,研究三维动画数据压缩方法对其数据的存储、传播和渲染技术至关重要.基于图像数据的结构化特征,计算机视觉领域提出了一系列高效图像压缩技术.鉴于三维动画数据与图像数据结构的差异,探讨三维动画数据结构化方法,进而探索改进图像算法以实现一种新的三维动画数据压缩方法.具体而言,首先研究对三维模型顶点...     

Microcalorimetric Investigation of the Interaction of Carbon Monoxide with Coprecipitated Cupric Oxide—Zinc Oxide Catalysts in Well-Defined Oxidation States

Carbon monoxide is readily adsorbed onto copper—zinc systems of different copper content. The adsorptive capacity, the heat and the kinetics of the interaction depend upon the oxidation state of the sample. The prevailing interaction on fully reduced samples is adsorption of carbon monoxide on copper metal, whereas in the case of partially oxidized samples and in that of cupric oxide—zinc oxide obtained by calcination of the precursor, redox reactions occur involving reduction of the surface, in parallel with the coordination of carbon monoxide on copper centres in various oxidation states. The heat of coordination of carbon monoxide onto copper (O) and copper (I) centres is in the range 66–43 kJ/mol and 110–66 kJ/mol respectively. The assignments have been made on the basis of the correspondence between carbonyl IR frequencies and heat of adsorption. Quantitative data on adsorption are also discussed in terms of the effect of the dispersion of the active phase and the role of the zinc oxide matrix.     

轨道-箱梁结构振动传递的模型试验研究

以京沪高铁常用的32 m无砟轨道箱梁结构为原型进行了模型试验,其中模型为轨道-箱梁结构.根据1/10的几何相似比,介绍了试验模型各结构的设计与制作过程,荷载激励由激振器施加.试验结果表明:轨道板振动在500-1024 Hz频段内衰减缓慢,底座板和顶板振动在0-1024 Hz频段内衰减较快;振动由顶板传递至翼缘板的过程中...     

生态高校校园热微环境探讨

随着自然环境的破坏,高校校园生态化已经成为发展的必然,通过从外部环境、校园规划、建筑设计及建筑节能几方面探讨了相应的热微环境改善措施,以确保生态校园具有良好的热微环境。     

基于改进的GRA-即时学习算法的镨/钕元素组分含量预测

针对现有稀土元素组分含量模型具有离线、时滞大、抗干扰能力弱等问题,提出一种改进的GRA-即时学习算法(GRA-JITL-LSSVM)建立稀土萃取过程组分含量在线检测模型.首先,采用灰色关联分析方法(GRA)分析输入输出变量之间的变化趋势和关联程度,采用哈希表确定学习集大小,确保数据相似度信息的完整性和学习集的合理性,据此建立最小二乘支持向量机(LSSVM)模型,并引入数据库更新准则,提高模型的抗干扰能力;然后,为了保证GRA-JITL-LSSVM模型参数的全局最优,提出一种带有停滞回溯策略的遗传算法(SBS-GA),并对SBS-GA的收敛性进行分析验证;最后,通过镨/钕萃取现场数据进行仿真实验,结果表明所提出SBS-GA算法能够保证寻优参数的全局解,所提出的GRA-JITL-LSSVM实时性高、预测精度好,可用于稀土萃取生产现场元素组分含量的在线检测.     

一种单相Vienna整流器及其控制方法

针对三相单相输入兼容场合使用的电动汽车直流充电模块,在三相Vienna整流器结构的基础上,提出了一种单相Vienna整流器结构及3种调制方法。第1种调制方法中2组开关管共用一个调制波,同时通断;第2种调制方法中一组开关管恒通,另一组开关管工作在高频PWM模式;第3种调制方法为2组开关管有2个独立的调制波。分析表明,第3中调制方法具有实现宽范围输出和能够调整输出电压不平衡的优点。基于第3种调制方法,建立了该整流器的数学模型,进而提出了含有输出电压upn与输出电压差Δupn两个控制环的整流器控制方法。通过对一个110 V AC输入的整流器的仿真和实验表明,只有第3种调制方法能够既实现200～380 V DC的宽范围输出电压,又能在输出电容和负载不平衡的条件下实现输出电压的平衡。     

基于FSM的电力远动规约设计

电力系统于1998年开始推行新的电力系统远动规约标准IEC60870-5-101,为了便于该规约的推广应用,编写较好的应用软件,引入有限状态机FSM(FiniteStateMachine)进行设计,并且基于面向对象技术提出一种高度结构化的有限状态机的实现框架。同时,应用有限状态机理论,抽象出链路层对象的有限状态机模型,并用状态图进行描述。有限状态机实现框架的引入,实现了灵活的复用机制,提高了系统的健壮性和可维护性。通信软件的开发,提供了一种比较便捷通用的开发模式,且现场实际运行良好。