基于快速非支配排序遗传算法的阻尼器多目标优化布置

将快速非支配排序遗传算法(NSGA-Ⅱ)和并行遗传算法相结合,提出内嵌NSGA-Ⅱ的粗粒度-主从式并行遗传算法。该算法将种群分为多个子种群,每个子种群可独立并行执行NSGA-Ⅱ操作;达到迁移周期时,子种群之间执行迁移操作;完成迁移后,子种群再次独立并行执行NSGA-Ⅱ操作。以最大层间位移角和最大楼层加速度为目标函数,对14层消能减震钢框架结构上的阻尼器布置位置进行优化分析。结果表明：该算法既实现多目标优化,又提高优化速度;对比常规隔层布置方法,该算法可使结构的层间位移角减震系数和加速度减震系数分别至少提高16.82%和16.01%。     

新安江模型参数多目标优化研究

水文模型的参数优化率定一直以来是水文预报领域的重要研究内容,当水文模型的结构确定后,水文模型参数的选择对水文模型整体性能和水文预报结果的好坏有着至关重要的影响.针对传统水文模型参数优选采用单一目标不能充分全面挖掘水文观测资料中蕴含的水文特征信息的缺陷,本文以新安江三水源模型为例,尝试采用多目标优化算法优化率定水文模型,算例应用分析表明,通过合理的选择目标函数的种类和数目,采用多目标进化算法优化率定模型参数,可以获得相对于单目标率定模型参数更优的结果.进一步,研究工作针对模型参数优化的结果进行分析,可以明显看出模型参数优化中存在“异参同效”现象,为后续模型参数不确定性分析等相关研究工作的开展做好了铺垫.     

城市供水系统多水源联合调度模型及应用

从城市供水系统的关键元素出发,通过系统网络拓扑分析,构建了"水源—水厂—分区用户"三层供水系统网络拓扑结构;基于此拓扑结构和兼顾整个供水系统的社会效益和供水成本两个调度目标,建立城市供水系统的多水源联合供水优化调度模型;利用NSGA-II(Non-dominated Sorting Genetic Algorithm II)算法进行模型求解,并给出最佳均衡解的选择规则;将该模型应用于南水北调中线一期工程通水后的天津市供水系统.实例研究结果表明,该模型实现了天津市不同来水丰枯组合情景下多种水源的合理分配,能够为决策者提供均衡社会效益与供水成本的详细供水方案,还可以在一定程度上反映出供水系统存在的工程问题,可为保障城市供水安全提供技术支撑.如最不利典型年来水情景下,总可供水量(14.73亿m3)大于天津市总需水量(13.77亿m3),但由于供水工程能力限制,特定供水规则下推荐的社会效益与供水成本折中方案的缺水量为2.44亿m3、总供水成本为32.6亿元.     

Neumann-Michell theory-based multi-objective optimization of hull form for a naval surface combatant

A numerical multi-objective optimization procedure is proposed here to describe the development and application of a practical hydrodynamic optimization tool, OPTShip-SJTU. Three components including hull form modification module, hydrodynamic performance evaluation module and optimization module consist of this tool. The free-form deformation (FFD) method and shifting method are utilized as parametric hull surface modification techniques to generate a series of realistic hull forms subjected to geometric constraints, and the Neumann-Michell (NM) theory is implemented to predict the wave drag. Moreover, NSGA-II, a muti-objective genetic algorithm, is adopted to produce pareto-optimal front, and kriging model is used for predicting the total resistance during the optimization process to reduce the computational cost. Additionally, the analysis of variance (ANOVA) method is introduced to represent the influence of each design variable on the objective functions. In present work, a surface combatant DTMB Model 5415 is used as the initial design, and optimal solutions with obvious drag reductions at specific speeds are obtained. Eventually, three of optimal hulls are analyzed by NM theory and a RANS-based CFD solver naoe-FOAM-SJTU respectively. Numerical results confirm the availability and reliability of this multi-objective optimization tool.