Numerical evaluation on shell buckling of empty thin-walled steel tanks under wind load according to current American and European design codes

Liquid storage steel tanks are vertical above-ground cylindrical shells and as typical thin-walled structures, they are very sensitive to buckling under wind loads, especially when they are empty or at low liquid level. Previous studies revealed discrepancies in buckling resistance of empty tanks between the design method proposed by the American Standard API 650 and the analytical formulas recommended by the European Standard EN1993-1-6 and EN1993-4-2. This study presents a comparison between the provisions of current design codes by performing all types of numerical buckling analyses recommended by Eurocodes (i.e. LBA-linear elastic bifurcation analysis, GNA-geometrically nonlinear elastic analysis of the perfect tank and GNIA-geometrically nonlinear elastic analysis of the imperfect tank). Such analyses are performed in order to evaluate the buckling resistance of two existing thin-walled steel tanks, with large diameters and variable wall thickness. In addition, a discussion is unfolded about the differences between computational and analytical methods and the conservatism that the latter method imposes. An influence study on the geometric imperfections and the boundary conditions is also conducted. Investigation on the boundary conditions at the foot of the tank highlights the sensitivity to the fixation of the vertical translational degree of freedom. Further, it is indicated that the imperfection magnitude recommended by the EN1993-1-6 is extremely unfavorable when applied to large diameter tanks. Comments and conclusions achieved could be helpful in order to evaluate the safety of the current design codes and shed more light towards the most accurate one.     

天津港南疆含油废水处理系统改造工程的设计与运行

采用混凝沉淀/水解酸化/膜生物反应器组合工艺对天津港南疆港区含油废水处理系统进行升级改造,实现了3600m3/d含油废水的达标排放。实际运行表明：在生化系统进水COD、BOD5、石油类、NH3-N、TN、TP分别为（400～2520）、（102～626）、（10～25）、（25～40）、（35～50）、（0.8～1.5）mg/L时,生化系统出水COD、BOD5、NH3-N、TN、TP分别为（31～46）、（3.2～9.6）、（1.2～2.9）、（3～12）、（0.13～1.0）mg/L,石油类未检出,出水水质达到《城镇污水处理厂污染物排放标准》（GB 18918—2002）的一级B标准。     

微波诱导活性炭催化氧化有机废水的研究进展

微波诱导活性炭催化氧化技术为有机废水处理提供了一种新的解决途径。全面阐述了该技术的催化氧化机理、微波反应器类型和处理效果,结合实际工程需求,对目前研究中存在的问题和发展趋势进行系统分析,以期为微波诱导活性炭催化氧化技术的工程化应用提供指导。     

非线性遗传优化海域水质耦合模型多参数反演方法研究

通过遗传算法和海域水质模型的有机耦合,提出了基于非线性遗传优化海域水质耦合模型多参数反演的新方法.将海域水质模型嵌入遗传算法模型中,以海域内部验证点位的误差函数为适应度,进行模型多参数的优化反演.文中以渤海湾海域水质模型多参数反演的“孪生”试验来验证方法的有效性.数值结果表明:该反演新方法具有较高的精度.     

Haze detection,perfection and removal for high spatial resolution satellite imagery

We present a technique to remove spatially varying haze contamination for high spatial resolution satellite imagery. This technique comprises three steps: haze detection, haze perfection and haze removal. Background Suppressed Haze Thickness Index (BSHTI) in haze detection is used to indicate relative haze thickness. ‘Fill sink’ and ‘flatten peak’ routines in haze perfection are applied to correct some spurious background effects. Virtual Cloud Point (VCP) method based on BSHTI is used in haze removal. Case study using two QuickBird images (hazy and clear) of Shenyang City in China proves the effectiveness of this technique except for those regions where haze is too thick. Comparison of the overlapped region between hazy and clear images using 76 paired polygon samples shows that squared correlation coefficient of each band between the two images becomes larger than 0.7. The advantages of this technique are that aerosol transparent bands are not needed and the technique is suitable for urban remote sensing.     

基于数据驱动神经网络模型的天津滨海区域综合承载力评价方法研究

随着天津滨海区域开发建设的不断深入,开展区域综合承载能力及其动态变化的研究,对于提高区域综合管理水平,实现可持续发展具有重要意义。本文以数据驱动神经网络方法为基础,建立以承载力影响因子与承载力等级之间非线性关系为核心的滨海区域综合承载力评价模型,并以天津滨海区域综合承载力评价的对比研究检验模型有效性。     

自然环境下煤尘表面水分蒸发特性的实验

为确定经济合理的喷洒工艺,采用现场实测的方法对煤尘洒水后其表面水分的变化进行了全年测定。在分析了自然环境下煤尘表面水分的蒸发迁移特性后指出：水分蒸发速率取决于相间浓度差、阻力以及初始接触面积等气-液界面上的特征参数。并将全年实测数据进行整理,得出煤尘表面水分变化速率k随大气湿度、空气流速及环境温度变化的定量表达式,明确了水分蒸发速率与各气象要素之间的关系。     

非线性隶属函数集对分析方法在海域水质评价中的应用

海域水环境质量评价是不确定性系统的分析问题,具有高度的非线性关系。本文建立了非线性隶属函数的集对分析综合评价方法与系统的评价步骤,提出了针对海洋水环境质量评价相应指标的非线性联系度函数构建方式。以渤海湾某工程海域的水环境质量评价为例,检验该方法的可行性,结果表明集对评价法具有简洁、易操作和高精度等优点,非线性隶属函数能更合理的量化评价指标的等级归属程度,评价结果具有更高的可信度。