A two-dimensional, multitvariate objective analysis scheme for simultaneous analysis of geopotential height and wind fields has been developed over Indian and adjoining region for use in numerical weather prediction. ...A two-dimensional, multitvariate objective analysis scheme for simultaneous analysis of geopotential height and wind fields has been developed over Indian and adjoining region for use in numerical weather prediction. The height-height correlations calculated using daily data of four July months (1976-1979), are used to derive the other autocorrelations and cross-correlations assuming geostropic relationship. A Gaussian function is used to model the autocorrelation function. Since the scheme is multivariate the regression coefficients (weights) are matrix.Near the equator, the geostrophic approximation relating mass and wind is decoupled in a way similar to Bergman (1979). The objective analyses were made over Indian and adjoining region for 850, 700, 500, 300 and 200 hPa levels for the period from 4 July to 8 July 1979, 12 GMT. The analyses obtained using multivariate optimum interpolation scheme depict the synoptic situations satisfactorily. The analyses were also compared with the FGGE analyses (from ECMWF) and also with the station observations by computing the root mean square (RMS) errors and the RMS errors are comparable with those obtained in other similar studies.展开更多
This work focuses on the updating-based identification of the three-dimensional orthotropic elastic behavior of a thin carbon fiber reinforced plastic multilayer composite plate. This consists in identifying the engin...This work focuses on the updating-based identification of the three-dimensional orthotropic elastic behavior of a thin carbon fiber reinforced plastic multilayer composite plate. This consists in identifying the engineering constants that minimize the relative deviations between the first eight experimental and three-dimensional finite element frequencies of the vibrating free plate. For this purpose, a multi-objective optimization procedure is applied;it exploits a Particle Swarm Optimizer algorithm (PSO) that is coupled to a metamodeling by the new response surfaces method procedure (NRSMP);the latter is based on numerical design experiments. The conducted sensitivity analyses indicate that the four engineering constants of the two-dimensional elasticity are the most influent.展开更多
内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿...内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿圈轮齿间的啮合传动作用,建立了内齿式回转支承参数化多体接触动力学模型。分析了沟道曲率半径、保持架兜孔孔径、初始接触角和轮齿变位系数等关键设计参数对回转支承齿轮啮合力、1号钢球与N1滚道的接触力、内齿圈质心轴向和径向振动位移的影响规律。在此基础上,采用试验设计(design of experiment,DOE)方法,对内齿式回转支承的关键设计参数进行全因子试验设计及计算,获得了多参数影响下回转支承的动态性能。结合线性加权法,运用统一量纲法和权系数法构造新的多目标优化函数,提出了回转支承动态性能的多变量多目标优化设计方法,得到回转支承的轮齿啮合力下降了49.27%,1号钢球与N1滚道的接触力下降了29.6%,内齿圈质心轴向振动位移减小了5.41%,内齿圈质心径向位移减小了15.88%,回转支承的性能得到了优化。研究结果为回转支承的动态设计提供了参考。展开更多
Integrated building design is inherently a multi-objective optimization problem where two or more conflicting objectives must be minimized and/or maximized concurrently.Many multi-objective optimization algorithms hav...Integrated building design is inherently a multi-objective optimization problem where two or more conflicting objectives must be minimized and/or maximized concurrently.Many multi-objective optimization algorithms have been developed;however few of them are tested in solving building design problems.This paper compares performance of seven commonly-used multi-objective evolutionary optimization algorithms in solving the design problem of a nearly zero energy building(n ZEB) where more than 1.610 solutions would be possible.The compared algorithms include a controlled non-dominated sorting genetic algorithm witha passive archive(p NSGA-II),a multi-objective particle swarm optimization(MOPSO),a two-phase optimization using the genetic algorithm(PR_GA),an elitist non-dominated sorting evolution strategy(ENSES),a multi-objective evolutionary algorithm based on the concept of epsilon dominance(ev MOGA),a multi-objective differential evolution algorithm(sp MODE-II),and a multi-objective dragonfly algorithm(MODA).Several criteria was used to compare performance of these algorithms.In most cases,the quality of the obtained solutions was improved when the number of generations was increased.The optimization results of running each algorithm20 times with gradually increasing number of evaluations indicated that the PR_GA algorithm had a high repeatability to explore a large area of the solution-space and achieved close-to-optimal solutions with a good diversity,followed by the p NSGA-II,ev MOGA and sp MODE-II.Uncompetitive results were achieved by the ENSES,MOPSO and MODA in most running cases.The study also found that 1400-1800 were minimum required number of evaluations to stabilize optimization results of the building energy model.展开更多
文摘A two-dimensional, multitvariate objective analysis scheme for simultaneous analysis of geopotential height and wind fields has been developed over Indian and adjoining region for use in numerical weather prediction. The height-height correlations calculated using daily data of four July months (1976-1979), are used to derive the other autocorrelations and cross-correlations assuming geostropic relationship. A Gaussian function is used to model the autocorrelation function. Since the scheme is multivariate the regression coefficients (weights) are matrix.Near the equator, the geostrophic approximation relating mass and wind is decoupled in a way similar to Bergman (1979). The objective analyses were made over Indian and adjoining region for 850, 700, 500, 300 and 200 hPa levels for the period from 4 July to 8 July 1979, 12 GMT. The analyses obtained using multivariate optimum interpolation scheme depict the synoptic situations satisfactorily. The analyses were also compared with the FGGE analyses (from ECMWF) and also with the station observations by computing the root mean square (RMS) errors and the RMS errors are comparable with those obtained in other similar studies.
文摘This work focuses on the updating-based identification of the three-dimensional orthotropic elastic behavior of a thin carbon fiber reinforced plastic multilayer composite plate. This consists in identifying the engineering constants that minimize the relative deviations between the first eight experimental and three-dimensional finite element frequencies of the vibrating free plate. For this purpose, a multi-objective optimization procedure is applied;it exploits a Particle Swarm Optimizer algorithm (PSO) that is coupled to a metamodeling by the new response surfaces method procedure (NRSMP);the latter is based on numerical design experiments. The conducted sensitivity analyses indicate that the four engineering constants of the two-dimensional elasticity are the most influent.
文摘内齿式回转支承兼有滚动轴承的回转支承特点和齿轮啮合传动特点,在联合载荷作用下其动态性能的影响因素众多,容易出现轮齿磨损或断齿、套圈滚道磨损和运行精度变差等问题。综合考虑钢球与内外套圈滚道、保持架兜孔的动态接触作用及内齿圈轮齿间的啮合传动作用,建立了内齿式回转支承参数化多体接触动力学模型。分析了沟道曲率半径、保持架兜孔孔径、初始接触角和轮齿变位系数等关键设计参数对回转支承齿轮啮合力、1号钢球与N1滚道的接触力、内齿圈质心轴向和径向振动位移的影响规律。在此基础上,采用试验设计(design of experiment,DOE)方法,对内齿式回转支承的关键设计参数进行全因子试验设计及计算,获得了多参数影响下回转支承的动态性能。结合线性加权法,运用统一量纲法和权系数法构造新的多目标优化函数,提出了回转支承动态性能的多变量多目标优化设计方法,得到回转支承的轮齿啮合力下降了49.27%,1号钢球与N1滚道的接触力下降了29.6%,内齿圈质心轴向振动位移减小了5.41%,内齿圈质心径向位移减小了15.88%,回转支承的性能得到了优化。研究结果为回转支承的动态设计提供了参考。
文摘Integrated building design is inherently a multi-objective optimization problem where two or more conflicting objectives must be minimized and/or maximized concurrently.Many multi-objective optimization algorithms have been developed;however few of them are tested in solving building design problems.This paper compares performance of seven commonly-used multi-objective evolutionary optimization algorithms in solving the design problem of a nearly zero energy building(n ZEB) where more than 1.610 solutions would be possible.The compared algorithms include a controlled non-dominated sorting genetic algorithm witha passive archive(p NSGA-II),a multi-objective particle swarm optimization(MOPSO),a two-phase optimization using the genetic algorithm(PR_GA),an elitist non-dominated sorting evolution strategy(ENSES),a multi-objective evolutionary algorithm based on the concept of epsilon dominance(ev MOGA),a multi-objective differential evolution algorithm(sp MODE-II),and a multi-objective dragonfly algorithm(MODA).Several criteria was used to compare performance of these algorithms.In most cases,the quality of the obtained solutions was improved when the number of generations was increased.The optimization results of running each algorithm20 times with gradually increasing number of evaluations indicated that the PR_GA algorithm had a high repeatability to explore a large area of the solution-space and achieved close-to-optimal solutions with a good diversity,followed by the p NSGA-II,ev MOGA and sp MODE-II.Uncompetitive results were achieved by the ENSES,MOPSO and MODA in most running cases.The study also found that 1400-1800 were minimum required number of evaluations to stabilize optimization results of the building energy model.
