波形钢腹板梁桥空间网格分析方法

至今日本在建和已建的波形钢腹板组合梁桥已经达到200多座,中国达到30多座,桥型有简支梁、连续梁、连续刚构及斜拉桥等,截面形式由最初的单箱单室发展到单箱多室。从受力性能和节约成本上看,50~150m跨径范围是最具有竞争力的。目前设计中多采用空间杆系模型、平面梁格模型和实体模型相结合的计算分析方法,但是,空间杆系模型缺乏空间效应精细化分析,如剪力滞效应、有效分布宽度问题、偏载系数问题等;由于平面梁格法在等效原理上的近似性,不能准确反映箱形组合梁的剪应力分布和顶底板局部受力;实体模型很难和总体计算相结合。而空间网格模型可以实现精细化分析,并且具有分析完整性、验算应力全面性,弥补了目前分析方法的不足。通过实体模型与空间网格模型的实例验证,可知两种模型的应力和位移的计算结果几乎一致,说明了网格模型的适用性和精确性。     

泵车电气系统全功能检测与评估系统

本文开发了一套泵车电气系统全功能检测与评估系统,通过实时采集各种传感器数据、ECU输出点、CAN总线数据,同时虚拟底盘发动机转速信号、变速箱转速信号、空挡倒档信号、油门开度、PTO工作状态等信号以及泵车上装、泵送压力、油温信号、主油缸位置、臂架位置等各种上装信号,发送给电控柜及E C U,通过软件编程实现电气全功能检测并做出相应可靠性评估。     

徐州市云龙湖风景名胜区空间布局生态策略研究

本文从风景名胜区与其所依托的城市地理区位角度出发,研究风景名胜区与城市之间的相互关系,并以徐州市云龙湖风景名胜区为例,提出适宜徐州市云龙湖风景名胜区的生态空间布局策略,将风景名胜区与与城市特色有效结合,促进二者协调发展。期望该研究能为我国其他风景名胜区的空间布局策略提供借鉴。     

全尾矿废石骨料高强混凝土的试验研究

从资源再生、生态环境保护和循环经济的角度出发,以重新级配后的密云地区铁矿废石为粗骨料、密云地区铁尾矿为细骨料,将铁尾矿与矿渣、水泥熟料、脱硫石膏通过梯级混磨得到混合料,与单独磨细的钢渣粉混合为胶凝材料,加入减水剂和水后制备成高强混凝土材料,并采用X射线衍射(XRD)、扫描电子显微镜(SEM)、能谱分析(EDS)等手段进行微观结构与物相组成的变化研究,进而分析反应机理。所制备的混凝土的固废总比例达到91%,使用废石代替天然石子,铁尾矿代替天然砂子,其天然砂石替代率达到100%,制得的混凝土试块28 d抗压强度达到75.92 MPa。     

活性炭的改性及其对苯酚吸附行为的研究

通过正交试验的方法,优化活性炭的改性条件;并以活性炭为载体,氢氧化钠溶液为改性剂,在最优条件下制备改性活性炭;测定了改性前后活性炭的比表面积及表面酸性官能团的含量;考察了改性前后活性炭对苯酚的吸附行为。结果表明,在NaOH溶液浓度为0．1mol／l,浸渍时间为3h,活化时间为3h,活化温度为400℃的情况下,改性活性炭吸附效果最佳,苯酚吸附量为149．05mg／g,比未改性活性炭的吸附量提高了61．97％;NaOH-改性活性炭的比表面积为1046．10m2／g,比未改性活性炭的比表面积增加了12．42％,改性后表面的酸性基团含量降低,碱性增强;Freundlich和Langmuir二种等温线模型均能较好的反应活性炭对苯酚的吸附行为,其中Freundlich模型更为理想。     

有机玻璃仿水晶像制作

采用铸塑本体聚合法,空气浴生产有机玻璃仿水晶像,其主要生产原料有MMA、BPO以及相片、风景照、明信片、杂志广告页等内嵌物。探讨了生产这种有机玻璃仿水晶像的生产工序及注意事项。实验证明,通过此法可直接生产大而薄、图象清晰、晶莹剔透的密封式有机玻璃仿水晶像。     

硅烷改性聚合物密封剂的研究进展

详细阐述了硅烷改性预聚体的合成方法和硅烷改性聚合物密封剂的制备及固化机理,总结了国内外硅烷改性聚合物密封剂的研究现状及进展,最后分析了硅烷改性聚合物密封剂在我国工业发展中的重要作用。     

Fractionating soluble microbial products in the activated sludge process

Soluble microbial products (SMP) are the pool of organic compounds originating from microbial growth and decay, and are usually the major component of the soluble organic matters in effluents from biological treatment processes. In this work, SMP in activated sludge were characterized, fractionized, and quantified using integrated chemical analysis and mathematical approach. The utilization-associated products (UAP) in SMP, produced in the substrate-utilization process, were found to be carbonaceous compounds with a molecular weight (MW) lower than 290 kDa which were quantified separately from biomass-associated products (BAP). The BAP were mainly cellular macromolecules with an MW in a range of 290-5000 kDa, and for the first time were further classified into the growth-associated BAP (GBAP) with an MW of 1000 kDa, which were produced in the microbial growth phase, and the endogeny-associated BAP (EBAP) with an MW of 4500 kDa, which were generated in the endogenous phase. Experimental and modeling results reveal that the UAP could be utilized by the activated sludge and that the BAP would accumulate in the system. The GBAP and EBAP had different formation rates from the hydrolysis of extracellular polymeric substances and distinct biodegradation kinetics. This study provides better understanding of SMP formation mechanisms and becomes useful for subsequent effluent treatment.     

An unsaturated model for request mechanisms in WiMAX

Worldwide interoperability for microwave access (WiMAX) based wireless metropolitan area networks have recently received wide attention as they support high data rates with great quality of service (QoS) capabilities. In order to support QoS, bandwidth request (BW-REQ) mechanisms are suggested in the WiMAX standard for resource reservation. In this letter we propose a simple and accurate analytical model for the performance analysis of contention-based bandwidth request mechanisms. The accuracy of this model is verified with simulation results.