环境友好的近自然型鱼道

鱼道是帮助鱼类顺利通过闸坝等障碍物的专用设施,在维系河流连续性与生物种群交流方面具有不可替代的作用。近自然型鱼道是目前国际上十分流行的鱼道布置形式,其典型特点是利用漂石与天然河道床沙质构建尽可能接近于天然河流的水流流态。与传统的工程鱼道相比,近自然型鱼道由于构建了鱼类熟悉的水流流态,因而往往具有更高的过鱼效率。本文全面介绍了近自然型鱼道的设计理念、类型、构造布置特点、设计原则、以及水力计算方法,并对我国鱼道技术的进一步发展提出了若干建议。     

多管程管壳式换热器管箱法兰的强度计算

多管程、高压、高温换热器管箱法兰的垫片密封问题对法兰强度的影响 ,在有关的标准规范中没有相关说明 ,设计中往往被忽略了。通过计算实例进行分析 ,可见其影响有时还比较大 ,建议通过折算进行强度计算 ,确保其安全可靠。     

Reducing the Compaction Segregation of Hot Mix Asphalt

This paper presented the methods of reducing the compaction segregation of asphalt layer by improving the operating characteristics of roller and paver. The fit formula, which expresses the compaction rule of the paving layer after passing different rolling passes of the steel wheel roller, was also put forward. The measured results of test road show that when some technical methods are adopted, the compaction segregation can be controlled.     

四辊可逆式粗轧机万向接轴晃动因素分析及解决对策

该文分析了万向接轴晃动的主要原因，研究了解决方案。     

在四辊孔型中轧制时中性角的确定

本文研究了由两个水平辊和两个立辊所构成的四辊孔型中轧制时的中性角。根据不同的传动方式、受力状态、孔型系统和材料的加工硬化程度,得到了相应的中性角公式。     

粗轧过程轧制力BP神经网络预报

利用BP神经网络 ,以某热轧厂粗轧机组数据库中的数据为训练样本 ,采用两种训练方案 ,对粗轧过程轧制力进行预测。BP网络的预报精度 ,既与训练样本的选取有关 ,又与隐层节点的个数以及相对化系数的大小有着密切的联系。以上因素选取得当 ,能够提高网络的预报精度 ,若选取不当 ,则降低网络的预报精度     

浅论小模数直伞齿轮的齿形加工方法

本文从大、小锥齿轮轴的齿形加工过程说明小模数直伞齿轮的齿形加工方法。     

Quantification of denitrification potential in carbonaceous trickling filters

Biofilm samples from a carbonaceous trickling filter (TF) were evaluated in bench scale reactors to determine their maximum potential denitrification rates. Intact, undisturbed biofilms were placed into 0.6 L bench-scale reactors filled with sterilized, primary clarifier effluent spiked with nitrate to a final concentration of 16-18 mg/L as N. Dissolved oxygen concentrations were maintained between 2 and 4 mg/L in the bulk aqueous phase. Nitrate loss from the reactors was monitored over a 5h period. Denitrification rates of 3.09-5.55 g-N/m(2)day were observed with no initial lag period. This suggests that the capacity for denitrification is inherent in the biofilm and that denitrification can take place even when oxygen is present in the bulk aqueous phase. There were no significant differences in denitrification rates per unit area of media (g-N/m(2)day) either between (a). experimental runs or (b). sampling locations over the trickling filter. This suggests that denitrification potentials are uniform over the entire volume of the full-scale TF. For wastewater treatment plants with TFs that currently nitrify downstream, this approach may be used to meet less stringent permitted discharge concentrations and may allow some facilities to postpone or eliminate construction of additional unit processes for denitrification.     

沙钢1700mm热连轧V2粗轧机接轴及辊系技术改造

分析了沙钢1700mm热连轧V2粗轧机设备结构存在的问题,提出了针对性的改造方案,在热连轧粗轧机上首次采用了工作辊提升轨道这一结构形式。改造后,不仅有效提高了作业时间,还有效降低了维修费用。