Preparation and performance of oxidative poly-silicon-ferric coagulant PSFN

1 Introduction1 The development of industries and agricultures has caused serious pollution to surroundings, which increases the concentration of DOM [1] in water sources. As an essential part of coagulation, coagulant having higher removal of DOMs has be…     

新型锌铝合金焊接技术研究

本文采用氧一乙炔气焊方法,对新型锌铝合金铸件进行了焊接试验研究。摸索出了一 套简便可行的焊接工艺。焊接后合金的强度、硬度没有下降,而塑性略有提高。金相检 验结果表明,焊缝组织比砂型铸造组织致密,晶粒细化。焊缝金属与母材金属熔合得 很好。      

Hydrography, currents and distribution of suspended matter during a dumping experiment in the western Baltic Sea at a site near Warnemünde

During a dumping experiment on 20/21 June 2001, an extensive data record was collected to understand the dynamical processes in the water column of the investigation area and to validate model results. Weak westerly winds with strongly changing cloud coverage characterized the meteorological situation. During the second day the wind calmed down and moved shortly to easterly directions. The water column was characterized by a strong vertical stratification with discontinuity layers in temperature and salinity in 12 and 16 m. The current regime was dominated by outflow at the water surface and inflow along the German coast, with strong current shearing in the dumping area. The suspended matter clouds could be identified by optical methods and ADCP (Acoustic Doppler Current Profiler) scattering intensity. During the experiment the suspended matter plumes were only visible at the surface up to 1 h after the dumping. The aerial photographs document that the particle clouds at the surface drifted to the west and, after approximately 40 min, they were only weakly visible. The fine material was concentrated in the discontinuity layer leading to substantially higher values of optical parameters and suspended matter concentration than measured in the surface clouds. Due to the vertical current shears the material was transported in the water column in different directions. At the first day the maximum of the suspended matter in the discontinuity layer was in the north-western corner and in the bottom layer in the northeast corner of the dumping area. Strong wind conditions after the dumping led to periodical resuspension processes.     

连盐高速公路软土工程特性及处治方案研究

连盐高速公路连云港段广泛分布海相软土,工程地质条件复杂,且工程性质差,软土地基处理成功与否是高速公路建设成败的关键技术之一。     

大跨径钢桥面浇注式沥青混凝土铺装应用研究

浇注式沥青混凝土具有优良的防水、抗老化性能、抗疲劳性能以及对钢桥面板优良的追从性,其在国外应用于桥面铺装已有多年的历史,取得了丰富的经验。本文从浇注式沥青混凝土的材料组成设计、粘结层强度、混合料特性与路用性能、浇注式沥青混合料的生产与摊铺等方面出发,全面系统地研究了大跨径钢桥面浇注式沥青混凝土铺装技术。     

典型生产工艺对无碳化物贝氏体钢轨组织与性能的影响

基于矫直、回火和在线热处理3种典型钢轨生产工艺,采用不同工艺组合工业试制5种无碳化物贝氏体钢轨;基于扫描电子显微镜、透射电子显微镜、背散射电子衍射法和X射线衍射法,分析无碳化物贝氏体钢轨的微观组织;采用布氏硬度、单轴拉伸、锯切应变片法、冲击韧性、断裂韧性和疲劳裂纹扩展速度测试等试验,研究典型生产工艺对无碳化物贝氏体钢轨组织和力学性能的影响。结果表明:矫直使无碳化物贝氏体钢轨中的残余奥氏体体积分数自12.44%降至10.6%,有利于促进亚稳态残余奥氏体的转变;回火稳定残余奥氏体,提升冲击韧性20%以上;在线热处理降低残余奥氏体体积分数,提高屈服强度19%以上,尤其能提高抗拉强度和冲击韧性,对轨底残余应力的影响不大。据此,为了综合提升无碳化物贝氏体钢轨的耐磨性和抗接触疲劳性能,在提高屈服强度和抗拉强度的同时增大残余奥氏体体积分数,以提升加工硬化能力和塑性。     

纳米 Al2O3 改性沥青的制备及其性能研究

为了研究纳米Al2O3改性剂对A-70#基质沥青物理性能、流变特性的影响及其微观改性机理。基于室内试验制备了不同掺量（1%、2%、3%、4%、5%）的纳米Al2O3改性沥青,对其进行三大指标、黏度、流变、抗老化性能及其傅里叶红外光谱试验测试。结果表明：加入纳米Al2O3之后,基质沥青的软化点和黏度提高,针入度及延度下降,纳米Al2O3最佳掺量为4%。由流变试验结果可知,纳米Al2O3可以提升基质沥青的车辙因子,显著增强其高温稳定性,抗老化性能得以提升,但对低温抗裂性能不利。根据微观分析结果,纳米Al2O3与基质沥青之间既产生了物理变化,又有微弱的化学反应存在。     

壁可法修补混凝土裂缝雷达检测技术的研究

混凝土结构普遍存在使用过程中出现裂缝的现象，混凝土裂缝修补技术在土木工程中应用越来越广泛，但裂缝修补检测技术却相对滞后，缺乏裂缝修补效果的检测手段。根据电磁波在介质中传播时，路径、电磁场强度与波形随所通过介质的电性质及几何形态而变化的特性，利用探地雷达获得裂缝中不同填充介质在雷达图像巾的特征及规律，辨别填充介质，来评价壁可法修补裂缝的效果。     

沥青稳定基层混合料的矿料级配研究

本研究的目的是选定合理的沥青稳定基层混合料级配,并研究其力学性能和疲劳规律。首先,通过与国外沥青稳定基层常用级配及国内相关级配的比较,以及大量的马歇尔试验和强度试验,初选出沥青稳定碎石1号(公称粒径26.5 mm)和沥青稳定碎石2号(公称粒径31.5 mm)两种级配类型;然后,在M TS810材料试验系统上进行了应力控制的疲劳试验,研究其抗疲劳性能。试验表明,这两种级配的沥青稳定基层碎石混合料的力学性能和疲劳性能优良,能够用于修筑高等级公路的沥青稳定基层。     

铁路车辆用6005A大型铝型材焊接性能研究

采用进口ER5356焊丝和自制Al-Mg合金焊丝对车辆用6005A大型铝型材进行了焊接,对焊接接头组织与性能进行了分析和研究。结果表明,6005A大型铝型材焊接接头最薄弱的部位位于离焊缝中心约15～20mm的热影响区内的软化区,软化区产生的主要原因是该区强化相粒子在焊接热循环过程中发生过时效,产生聚集粗化。