夯扩沉管灌注桩在广西的应用研究

本文结合广西工程地质特点,介绍夯扩沉管灌注桩的应用范围、工作机理、设计计算以及施工措施,并总结出夯扩沉管灌注桩的许多优点。     

基础水平倒角典型施工工艺

±500 kV德阳换流站基础数量多、分布密集,且均为独立外露型基础,为了进一步推动"两型一化"变电站建设新思路,立足于以用为先、简洁适用,创新优化、节约资源,以人为本、环境友好的建设原则,对基础混凝土倒角进行改进和提高,取消塑料线条安装,避免返工返修,最大限度减少资源浪费,节约成本,基础一次成优,有效对基础成品进行保护。     

糖基化终末产物对大鼠肾小管上皮细胞组织型转谷氨酰胺酶mRNA表达的影响

目的探讨晚期糖基化终末产物(Advanced glycosylation end products,AGEs)对大鼠肾小管上皮细胞NRK-52E组织型转谷氨酰胺酶(Tissue transglutanunase,tTG)mRNA表达及其对细胞外基质(Extracellular matrix,ECM)降解的影响。方法体外培养NRK-52E细胞,分别用体外合成的不同浓度的糖化牛血清白蛋白(AGE-BSA)及未经糖化的牛血清白蛋白(BSA)处理48h,ELISA法检测细胞培养上清中纤维连接蛋白(Fibronectin,FN)和Ⅳ型胶原蛋白(TypeⅣcollagen,ColⅣ)含量,RT-PCR检测细胞tTG mRNA的表达。结果与BSA组比较,50～200mg/LAGE-BSA组细胞上清中FN含量明显增加(P<0.01),25～100mg/L AGE-BSA组细胞上清中ColⅣ含量明显增加(P<0.05);AGE-BSA(50～400mg/L)可不同程度地刺激细胞tTG mRNA表达的增加(P<0.05);tTG mRNA表达增加与FN、ColⅣ分泌增多呈正相关(r值分别为0.911和0.872)。结论 AGEs能诱导大鼠近端肾小管上皮细胞tTG mRNA的表达,引起ECM主要成分FN和ColⅣ含量增加,提示tTG可能在AGEs引起的ECM积聚过程中,起到抑制ECM蛋白降解的作用,进而参与糖尿病肾病的病理过程。     

Flocculation of reed pulp suspensions by quaternary chitosan‐nanoparticle SiO2 retention aid systems

The microparticle retention aid system has been a focus on the studies of paper‐making chemicals. N‐(2‐Hydroxy‐3‐trimethylammonio)‐propyl chitosan chlorider [quaternary chitosan (QCS)]—nanoparticle SiO₂ dual component system was investigated in this work. The adsorpton kinetic experiments indicated that there was a very fast (<1 min) polymer adsorption under good mixing conditions. Adsorption of QCS onto the fiber surface was followed by a rearrangement to reach an equilibrium conformation. At the same time, QCS chains, existing on the surface of fiber, could permeate into the porous of the fiber, resulting in the reducing of zeta potential of the cellulosic fiber. In addition, the flocculation would be increased with the increasing of SiO₂ when the fiber substrates surfaces was net positively charged by an adsorbed QCS layer. It was also found that ionic strength decreased significantly the flocculation efficiency in pure QCS system, whereas the turbidity of the reed pulp suspension increased slightly with the increasing of NaCl concentration in QCS‐SiO₂ systems. The effect of shear force on the flocculation was tested. It was shown shear led to floc breakage and decreased the flocculation. These phenomena were very obvious for one‐component system (QCS or C‐St), but the microparticle system (QCS‐SiO₂ or C‐St‐SiO₂) was shear resistance. Dynamic drainage experiment indicated that the turbidity of white water was decreased with the increasing of dosage of SiO₂ in experimental level. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Intrinsic viscosity–number average molecular weight relationship for poly(1,4‐butylene adipate) diol

The relationship between number average molecular weight (M_n) and intrinsic viscosity ([η]) was studied for poly(1,4‐butylene adipate) diol (PBAD) in tetrahydrofuran, toluene, and ethyl acetate at 25°C. Thus, a series of PBAD samples were prepared by polymerization between 1,6‐adipic acid and 1,4‐butanediol. The values of M_n for the samples were determined by end‐group analysis as well as by ebulliometry, and the average difference of M_n between the two analysis ways was about 2.69%. The Mark–Houwink–Sakurada equations for PBAD were obtained to relate [η] with M_n in the range of 1900–10,000. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

机械密封摩擦副端面分形维数的优化

机械密封摩擦副接触端面的分形维数对摩擦副摩擦磨损特性和密封性能有着重要的影响。依据机械密封摩擦副端面接触分形模型和泄漏分形模型,分别研究了有利于减轻端面磨损的最优分形维数和基于允许泄漏率的最优分形维数。用数值计算方法得出了NHM70型机械密封摩擦副端面弹性接触面积比Are/Ar与分形维数D的关系曲线及泄漏率q与分形维数D的关系曲线。在自行设计的试验装置上,进行了NHM70型机械密封试验研究。通过理论计算和试验验证表明,在综合考虑磨损率、泄漏率和加工成本后,NHM70型机械密封软质环端面的最优分形维数为1.61。     

多相介质泵用高压密封设计及性能分析

针对多相介质泵用机械密封运行特点,为避免介质含气量大范围波动而影响密封端面润滑膜的稳定性,开展高压双端面机械密封结构和端面槽型设计,通过变形校核证明结构设计合理。建立密封端面深槽流体润滑模型,采用数值计算方法进行求解,分析不同开槽面积比的圆弧型槽的端面泄漏量、开启力等主要密封性能随工况参数的变化规律。结果表明：高压状态下,密封端面开深槽能有效改善端面润滑状态;端面泄漏量和开启力随着开槽面积比的增大而变大,同时压力越大,端面泄漏量和开启力也越大,但转速对端面泄漏量和开启力的影响不大。对设计的密封进行台架性能试验验证,获得的密封端面泄漏量变化规律与数值计算结果趋势保持一致。     

空冷汽轮发电机端部电磁场与涡流损耗研究

针对大型空冷汽轮发电机端部磁场分布和各结构件的涡流损耗难以准确计算的问题,对大型空冷发电机端部结构进行三维实体建模,建立了电机端部三维非线性瞬态涡流场的数学模型,阐述了对激励源的选择和结构件建模的方法,较全面地考虑了材料特性、结构件形状等因素对电机性能的影响。以一台200MW空冷汽轮发电机为例,用有限元法对其在额定工况下的端部电磁场分布和结构件中的涡流损耗进行计算。将所得的结果与实测值进行比较,分析表明误差在工程应用的允许范围内,表明此种方法可以用于大型空冷汽轮发电机的端部电磁场与涡流损耗的计算当中。     

390H型燃汽轮发电机定子绕组端部固定结构特点分析

从设计角度深入分析了定子绕组端部固定结构及特点、绕组端部响应试验数据、评估标准,对设计大型汽轮发电机绕组端部固定方式具有借鉴意义。     

交流变电站500kV母线接地器的配置

针对现有常规母线接地器配置计算方法,介绍了根据母线电磁感应电压分布情况对母线接地器距离进行计算的方法。以长春某500 kV变电站为例,对可能存在的电磁感应电压,端部效应和平行导线互感影响等因素,用2种电流分布曲线分别计算接地器距母线端部及接地器之间的距离,经计算,该变电站2组母线接地器间的允许距离为172.33 m,各需2组接地开关即可。