顶部定常吸气对高层建筑模型气动力的影响

为减少高层建筑受到的风荷载,提高高层建筑抗风性能,提出一种顶部吸气的主动控制方法。在一高宽比为H/d=5的正方形截面柱体的高层建筑模型上,通过在其顶部前边缘开设狭缝进行吸气来实现流动控制。通过风洞试验研究了顶部吸气对气动力与顶部分离流的影响.利用流动可视化与流场测试结果揭示了顶部狭缝吸气的控制机理.实验对比了不同吸气系数Q(=U/U_∞,U为狭缝吸气速度)对气动力控制效果的影响,并对Q=0,1和3的三种工况下风压分布与顶部剪切流进行了详细对比.研究发现狭缝吸气改变了顶部分离流特性,并对模型所有高度上的气动力均有显著影响.Q=1时控制效果最佳,脉动阻力与脉动升力分别减小17.8%和45.5%.此时顶面分离流被削弱并伴随有再附现象且湍流强度较大,最有利于顶部剪切流与尾流间的动量交换,从而削弱柱体展向涡脱落与脉动气动力.     

电力公司抄表管理模式分析

本文结合供电企业的抄表现状,探讨了供电企业的抄表管理模式,分析了实施抄管分离的意义,并提出了几种行之有效的实现抄管分离的解决办法.     

Effects of coagulation bath temperature on structure and performance of poly （vinyl butyral） hollow fiber membranes via thermally induced phase separation

Poly （vinyl butyral） （PVB） hollow fiber membranes were fabricated via thermally induced phase separation （TIPS）. The effects of coagulation bath temperature （CBT） on the structure and performance of membranes were investigated in detail. The morphologies of the membranes were studied by scanning electron microscopy （SEM）, the performances of water permeability, rejection, breaking strength and elongation were measured, respectively. The results indicate that all the membranes have the asymmetric morphology and the thickness of the skin layer decreases and the pore size of the outer layer increases with the increase of CBT. The permeability of membranes prepared at air gap 1.0 cm and take-up speed 0.253 m/s increases from 1.047×10-7 to 5.909×10-7 m3/（m2·s-kPa） with the CBT increasing from 20 ℃ to 40℃, and sharply increases to 35.226×10 7 m3/（m2.s.kPa）once the CBT arrives at 50 ℃. While the carbonic ink rejections have no significant decrease, totally exceed 98%, but that of acid-maleic acid copolymer greatly decreases with the increase of CBT. Both the breaking strength and elongation decrease with the increase of CBT.     

超纯氢纯化技术示范成功

近日,中科院大连化物所甲烷高效转化新材料与新过程研究组开发的高性能金属钯复合膜材料,在超纯氢气纯化技术示范上获得成功,示范规模为30 m3/h氢气。该团队采用纯度为99.99956%的氢气作为原料,其中含杂质氮气3.81×10-6,杂质二氧化碳0.6×10-6,在保持91.8%氢气回收率条件下,产品氢气纯度达到99.9999996%,其中氮气含量为4.3×10-9,未检出二氧化碳。在稳定性考察过程中,24 h     

高性能新型MgB2中空超导线

转变温度为 3 9K的MgB2 超导体发现不久 ,就观测到这种材料具有一些有利于实际应用的特性。例如 ,在冷加工状态 ,未经过热处理的粉中即有持续超导电流。磁光成像观测发现 ,磁场几乎从高密度、多晶块状材料内部完全排出。这说明MgB2 超导体晶界不会对超导电流起阻隔作用。这一特性使制造MgB2 为基的超导体变得容易。目前主要有 2种粉末装管法 ,一种是原位法 (insitu) ,另一种是先位法 (exsitu)。在制作过程中 ,采用细粉、合适的热处理制度并施以高应变能得到最好的结果。用先位法制备的样品在高场下具有较好的电流传输特性 ,而在低场或自…     

叔胺萃取分离精炼铂的新工艺

用三烷基胺（Ｎ２３５）萃取分离铂，考察了稀释剂、改质剂浓度、料液酸度对分配系数的影响，从复杂的工业料液中，用Ｎ２３５萃取、洗涤、反萃、再生及精炼铂的工艺技术。     

SHS制备陶瓷内衬复合管中多孔层抑制措施

研究了在重力自蔓延法制备陶瓷内衬复合钢管过程中在复合热管底部出现的多孔层现象,以及各类添加剂对其的影响,分析了多孔层出现的原因,探讨了抑制措施。试验结果表明,SiO2的存在是产生多孔层的主要原因,并且多孔层部分随着SiO2含量的增加而增加,助燃剂也能导致多孔层的出现。当SiO2的质量分数小于2%时,适量加入氟化物,可以有效减少多孔层的体积。     

Flow of gas-liquid-solid system and its application in packed flotation column

A packed flotation column, which is packed with multiple board ripple packings, was described. Based on comprehensive steady state models, chemical reactor developed previously in chemical engineering subjects, have been extended to packed flotation column for mineral separation. The experimental results verify that tarts in series model is better than axially-dispersed plug flow model to describe flow pattern in the collection zone of column by RTD (residence time distribution), and the error of experimental data and calculated data of both models are 0. 07 % - 0. 1% and 0. 18 % - 0.45 % respectively. And, RTD of gas phase was also considered, results also show that gas in the whole column appears plug flow. The cleaning process through adding wash water in froth zone of column was described, and the effect of superficial air vdodty and superficial wash water vdocity on the cleaning action of froth zone were discussed. Flotation experiment for single column was conducted for phosphate ores. The recovery for P2Os was 85.8%, and the grade was 26.8%.     

40m后张法预制安装工形梁原位现浇施工方法

1简述40m后张法组合工形梁梁高2.3m,但是腹板宽仅18cm,顶板宽66cm,底板宽54cm。梁中钢绞线加预应力后,由于梁较长宽度较小,横向刚度不足,当出现侧向偏心力后,便会加大侧弯,特别是安装过程中在工形梁被吊起形成空中自由体无约束力时,极易导致梁体破坏,甚至发生安全事故。