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101.
随着岩土工程技术的进步与相关学科的发展,新的边坡稳定性分析方法不断涌现;另一方面,因对边坡工程地质条件缺乏足够的认识而评价方法选择不当导致工程事故时有发生。因此对边坡稳定性评价方法的原理、假设条件及适用范围进一步疏理很有必要。首先从评价方法的学科领域、基本原理、评价模型的假设条件等角度将其分为工程地质经验评价法、工程力学理论分析法、应用数学理论分析法、试验模拟法和现场监测与预测分析法等五大类。选择代表性的方法介绍每类评价方法的研究现状,指出存在的问题,分析与归纳各类评价方法的优缺点及其适用条件。最后对边坡稳定性研究及其评价方法的发展趋势进行展望。 相似文献
102.
电站锅炉飞灰不均匀磨损会大幅降低设备的使用寿命。针对某600 MW机组选择性催化还原脱硝装置喷氨管道不均匀磨损问题,利用计算流体力学数值模拟计算软件完成了脱硝装置的磨损分析。结果表明,数值计算得到的喷氨管道严重磨损区域与实际检修过程中发现的严重磨损区域相符,说明数值模拟分析可用于分析复杂烟气环境下的磨损问题。计算结果表明,喷氨管道的主要磨损区域在距离烟道壁面200 mm范围以内,最大磨损速率达到3.22×10^-7kg/(m^2·s),最大磨损速率是平均磨损速率的4019倍。通过最大磨损速率计算管道磨损失效时间为40313 h,与实际磨穿失效时间基本相符,说明数值模拟计算也可作为定量分析复杂烟气环境磨损问题的一个重要工具。 相似文献
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105.
ABSTRACT The mixture of citrus fruits (orange, grapefruit, mandarin, and lemon) wastes was utilized to obtain high surface area activated carbon (AC) by H3PO4 activation. The production conditions were optimized and the optimum conditions were determined. The optimal-activated carbon (CFWAC) was characterized by various physicochemical techniques. CFWAC was also used as a sorbent for Pb (II) ions from water. Batch experiments were performed to explore the adsorption capacity and mechanism. The Langmuir isotherm and pseudo-second-order kinetic model showed good fitness to the experimental data. The maximum Pb (II) adsorption capacity of CFWAC was found to be 163.93 mg/g. 相似文献
106.
107.
《Fuel》2006,85(12-13):1772-1780
With a view to developing onboard generation of selective reductants for NOx removal from diesel engine exhaust we compared the performance of a primary, secondary and tertiary amine to NH3 using a typical mini core NH3-SCR catalyst. Primary amines with short hydrocarbon chains, e.g. CH3NH2 (maximum NOx conversion, 50%) approached the NOx conversion obtained using NH3 (maximum NOx conversion, 70%). Increasing the amine to NOx ratio greater than 1 results in NOx conversions closer to those of NH3 (maximum NOx conversion increased to 60%). Secondary and tertiary amines had smaller NOx conversions as a function of temperature and the drop in NO and NOx conversion decreased with increasing amine hydrogen substitution. Also, the maximum NOx conversion for each reductant tends to move to a lower temperature as the degree of substitution increases.Unlike NH3, the amines can react in the gas phase at temperatures within the range of diesel engine exhaust. Due to this gas phase reactivity the NOx conversions measured using the mini core SCR catalyst also contain a gas phase conversion component. Gas phase conversions were investigated by replacing the mini core SCR catalyst with an equivalent length of quartz beads. Subtraction of the two results highlighted the differences between the mini core catalytic and gas phase conversions measured in this manner over the temperature range investigated. These differential NOx conversions for the three amines had maxima at about 375 °C. 相似文献
108.
In recent years, plenty of simulation research about the low impact development(LID) control effect has emerged, but studies on scheme comparison and evaluation are lacking. In this study, a comprehensive benefit evaluation system for LID, including environmental, economic, and social benefits, was established on the basis of Analytic Hierarchy Process(AHP) and urban storm water model. Above all, benefit identification, quantitative evaluation and scheme comparison of single LID measures were obtained according to site investigation, simulated calculation and theoretical analysis. Whereafter, LID combination plans were designed based on single LID measures with high comprehensive benefit values, and their comprehensive benefits were evaluated to obtain the optimal plan. Then, based on well-founded system combined with Storm Water Management Model (SWMM), the design and optimization of LID were conducted, with a case in Xi’an, China. It turned out that the preferential order of the LID single measures according to the comprehensive benefit was: bio-retention > rain barrels > low-elevation greenbelt > green roofs > permeable pavement. Five LID combination plans were designed based on bio-retention, rain barrels, low-elevation greenbelt, and green roofs. Evaluation results showed that plan I (bio-retention and green roofs) was the optimal LID combination plan. 相似文献
109.
《Desalination》2007,202(1-3):122-128
A nonwoven fabric module was utilized as a solid–liquid separation medium in a membrane bioreactor (MBR) for treating wastewater. The experimental results indicated that nonwoven fabrics had lower filtration resistance than microporous membranes in MBR applications. The optimal aeration intensity was approximately 0.01m3/m2 s. The effect of mixed liquor suspended solid concentration on filtration resistance was not significant at an operating flux of under 0.8m3/m2 d in the study range. The performance of nonwoven fabrics in a MBR application was further demonstrated in a pilot test. Chemical oxygen demand (COD) and suspended solids (SS) in the effluent were maintained under 60 and 10 mg/L, respectively, whereas influent COD varied from 800 to 1800mg/L. The transmembrane pressure was maintained below 5 kPa at a permeation flux of 0.18m3/m2 d. The experimental results demonstrated that nonwoven fabrics maintained stable operation in MBR applications under appropriate operating conditions. 相似文献
110.
《Expert systems with applications》2014,41(14):6274-6290
This paper revisits the classical Polynomial Mutation (PLM) operator and proposes a new probe guided version of the PLM operator designed to be used in conjunction with Multiobjective Evolutionary Algorithms (MOEAs). The proposed Probe Guided Mutation (PGM) operator is validated by using data sets from six different stock markets. The performance of the proposed PGM operator is assessed in comparison with the one of the classical PLM with the assistance of the Non-dominated Sorting Genetic Algorithm II (NSGAII) and the Strength Pareto Evolutionary Algorithm 2 (SPEA2). The evaluation of the performance is based on three performance metrics, namely Hypervolume, Spread and Epsilon indicator. The experimental results reveal that the proposed PGM operator outperforms with confidence the performance of the classical PLM operator for all performance metrics when applied to the solution of the cardinality constrained portfolio optimization problem (CCPOP). We also calculate the True Efficient Frontier (TEF) of the CCPOP by formulating the CCPOP as a Mixed Integer Quadratic Program (MIQP) and we compare the relevant results with the approximate efficient frontiers that are generated by the proposed PGM operator. The results confirm that the PGM operator generates near optimal solutions that lie very close or in certain cases overlap with the TEF. 相似文献