碳排放量、能源消费量、人口和经济增长存在着较为密切的关系,而作为清洁二次能源的电能,其消费使用量的多少影响着能源消费结构,进而影响着能源消费量。因此,电力消费强度和碳排放量之间存在着何种联系,是电力工业低碳之路需要考虑的...碳排放量、能源消费量、人口和经济增长存在着较为密切的关系,而作为清洁二次能源的电能,其消费使用量的多少影响着能源消费结构,进而影响着能源消费量。因此,电力消费强度和碳排放量之间存在着何种联系,是电力工业低碳之路需要考虑的问题。利用随机性环境影响评估模型(stochastic impacts by regression on population,affluence,and technology,STRIPAT),通过最小二乘回归方法测算碳排放量、人口、人均国民生产总值、电力消费量和能源消费量之间的碳排放影响系数。研究发现,人口、人均国民生产总值以及电力消费量和能源消费量之间的比值每发生1%的变化,将引起碳排放总量1.207%、0.901%以及?1.188%的变化,因此,在未来我国人口增长趋势放缓、国民经济保持7%以上较快发展的情况下,减少碳排放的途径应该从技术因素入手,通过提高电能占使用能源的比率、提高化石能源的使用效率和发展可再生能源来进行。展开更多
Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimizati...Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimization methods capable of providing the best trade-off designs compromising both criteria simultaneously. Although many studies have been performed on multi-objective optimization of vehicle suspension system, only a few of them have used probabilistic approaches considering effects of uncertainties in the design. However, it has been proved that optimum point obtained from deterministic optimization without taking into account the effects of uncertainties may lead to high-risk points instead of optimum ones. In this work, reliability-based robust multi-objective optimization of a 5 degree of freedom （5-DOF） vehicle suspension system is performed using method of non-dominated sorting genetic algorithm-II （NSGA-II） in conjunction with Monte Carlo simulation （MCS） to obtain best designs considering both comfort and handling. Road profile is modeled as a random function using power spectral density （PSD） which is in better accordance with reality. To accommodate the robust approach, the variance of all objective functions is also considered to be minimized. Also, to take into account the reliability criterion, a reliability-based constraint is considered in the optimization. A deterministic optimization has also been performed to compare the results with probabilistic study and some other deterministic studies in the literature. In addition, sensitivity analysis has been performed to reveal the effects of different design variables on objective functions. To introduce the best trade-off points from the obtained Pareto fronts, TOPSIS method has been employed. Results show that optimum design point obtained from probabilistic optimization in this work provides better performance while demonstrating very good reliability and robustness. However, other optimum points from deterministic optimizations violate the regarded constraints in the presence of uncertainties.展开更多
Traditional gust load factor(GLF)method,inertial wind load(IWL)method and tri-component method(LRC+IWL)cannot accurately analyze the wind-induced responses of super-large cooling towers,so the real combination formula...Traditional gust load factor(GLF)method,inertial wind load(IWL)method and tri-component method(LRC+IWL)cannot accurately analyze the wind-induced responses of super-large cooling towers,so the real combination formulas of fluctuating wind-induced responses and equivalent static wind loads(ESWLSs)were derived based on structural dynamics and random vibration theory.The consistent coupled method(CCM)was presented to compensate the coupled term between background and resonant response.Taking the super-large cooling tower(H=215 m)of nuclear power plant in Jiangxi Province,China,which is the highest and largest in China,as the example,based on modified equivalent beam-net design method,the aero-elastic model for simultaneous pressure and vibration measurement of super-large cooling tower is firstly carried out.Then,combining wind tunnel test and CCM,the effects of self-excited force on the surface pressures and wind-induced responses are discussed,and the wind-induced response characteristics of background component,resonant component,coupled term between background and resonant response,fluctuating responses,and wind vibration coefficients are discussed.It can be concluded that wind-induced response mechanism must be understood to direct the wind resistant design for super-large cooling towers.展开更多
文摘碳排放量、能源消费量、人口和经济增长存在着较为密切的关系,而作为清洁二次能源的电能,其消费使用量的多少影响着能源消费结构,进而影响着能源消费量。因此,电力消费强度和碳排放量之间存在着何种联系,是电力工业低碳之路需要考虑的问题。利用随机性环境影响评估模型(stochastic impacts by regression on population,affluence,and technology,STRIPAT),通过最小二乘回归方法测算碳排放量、人口、人均国民生产总值、电力消费量和能源消费量之间的碳排放影响系数。研究发现,人口、人均国民生产总值以及电力消费量和能源消费量之间的比值每发生1%的变化,将引起碳排放总量1.207%、0.901%以及?1.188%的变化,因此,在未来我国人口增长趋势放缓、国民经济保持7%以上较快发展的情况下,减少碳排放的途径应该从技术因素入手,通过提高电能占使用能源的比率、提高化石能源的使用效率和发展可再生能源来进行。
文摘Ride and handling are two paramount factors in design and development of vehicle suspension systems. Conflicting trends in ride and handling characteristics propel engineers toward employing multi-objective optimization methods capable of providing the best trade-off designs compromising both criteria simultaneously. Although many studies have been performed on multi-objective optimization of vehicle suspension system, only a few of them have used probabilistic approaches considering effects of uncertainties in the design. However, it has been proved that optimum point obtained from deterministic optimization without taking into account the effects of uncertainties may lead to high-risk points instead of optimum ones. In this work, reliability-based robust multi-objective optimization of a 5 degree of freedom （5-DOF） vehicle suspension system is performed using method of non-dominated sorting genetic algorithm-II （NSGA-II） in conjunction with Monte Carlo simulation （MCS） to obtain best designs considering both comfort and handling. Road profile is modeled as a random function using power spectral density （PSD） which is in better accordance with reality. To accommodate the robust approach, the variance of all objective functions is also considered to be minimized. Also, to take into account the reliability criterion, a reliability-based constraint is considered in the optimization. A deterministic optimization has also been performed to compare the results with probabilistic study and some other deterministic studies in the literature. In addition, sensitivity analysis has been performed to reveal the effects of different design variables on objective functions. To introduce the best trade-off points from the obtained Pareto fronts, TOPSIS method has been employed. Results show that optimum design point obtained from probabilistic optimization in this work provides better performance while demonstrating very good reliability and robustness. However, other optimum points from deterministic optimizations violate the regarded constraints in the presence of uncertainties.
基金Projects(50978203,51208254)supported by the National Natural Science Foundation of ChinaProject(BK2012390)supported by Natural Science Foundation of Jiangsu Province,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Traditional gust load factor(GLF)method,inertial wind load(IWL)method and tri-component method(LRC+IWL)cannot accurately analyze the wind-induced responses of super-large cooling towers,so the real combination formulas of fluctuating wind-induced responses and equivalent static wind loads(ESWLSs)were derived based on structural dynamics and random vibration theory.The consistent coupled method(CCM)was presented to compensate the coupled term between background and resonant response.Taking the super-large cooling tower(H=215 m)of nuclear power plant in Jiangxi Province,China,which is the highest and largest in China,as the example,based on modified equivalent beam-net design method,the aero-elastic model for simultaneous pressure and vibration measurement of super-large cooling tower is firstly carried out.Then,combining wind tunnel test and CCM,the effects of self-excited force on the surface pressures and wind-induced responses are discussed,and the wind-induced response characteristics of background component,resonant component,coupled term between background and resonant response,fluctuating responses,and wind vibration coefficients are discussed.It can be concluded that wind-induced response mechanism must be understood to direct the wind resistant design for super-large cooling towers.
