Based on the general relationship described by Cheng between the drag coefficient and the Reynolds number of a particle, a new relationship between the Reynolds number and a dimensionless particle parameter is propose...Based on the general relationship described by Cheng between the drag coefficient and the Reynolds number of a particle, a new relationship between the Reynolds number and a dimensionless particle parameter is proposed. Using a trial-and-error procedure to minimize errors, the coefficients were determined and a formula was developed for predicting the settling velocity of natural sediment particles. This formula has higher prediction accuracy than other published formulas and it is applicable to all Reynolds numbers less than 2× 10^5.展开更多
In the present paper, by introducing the effective wave elevation, we transform the extended elliptic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simpl...In the present paper, by introducing the effective wave elevation, we transform the extended elliptic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. （2003）, the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. （2007）＇s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly varying topography and wave breaking, the present model is applied to study： （1） wave refraction and diffraction over a submerged elliptic shoal on a slope （Berkhoff et al., 1982）; （2） Bragg reflection of monochromatic waves from the sinusoidal ripples （Davies and Heathershaw, 1985）; （3） wave transformation near a shore attached breakwater （Watanabe and Maruyama, 1986）. Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models （REF/DIF model and FUNWAVE model） show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.展开更多
Since the mild-slope equation was derived by Berkhoff （1972）,the researchers considered various mechanism to simplify and improve the equation,which has been widely used for coastal wave field calculation.Recently,s...Since the mild-slope equation was derived by Berkhoff （1972）,the researchers considered various mechanism to simplify and improve the equation,which has been widely used for coastal wave field calculation.Recently,some scholars applied the mild-slope equation in simulating the tidal motion,which proves that the equation is capable to calculate the tide in actual terrain.But in their studies,they made a lot of simplifications,and did not consider the effects of Coriolis force and bottom friction on tidal wave.In this paper,the first-order linear mild-slope equations are deduced from Kirby mild-slope equation including wave and current interaction.Then,referring to the method of wave equations’ modification,the Coriolis force and bottom friction term are considered,and the effects of which have been performed with the radial sand ridges topography.Finally,the results show that the modified mild-slope equation can be used to simulate tidal motion,and the calculations agree well with the measurements,thus the applicability and validity of the mild-slope equation on tidal simulation are further proved.展开更多
随着人工智能技术的发展,深度学习在体育领域的研究与应用也在逐渐增多。将人工智能技术应用于竞技体育运动视频分析,既是国内外理论研究关注的热点,也是促进竞技体育高质量发展的有效手段。通过Google Scholar、中国知网、Web of Scie...随着人工智能技术的发展,深度学习在体育领域的研究与应用也在逐渐增多。将人工智能技术应用于竞技体育运动视频分析,既是国内外理论研究关注的热点,也是促进竞技体育高质量发展的有效手段。通过Google Scholar、中国知网、Web of Science及SPORTDiscus数据库检索文献,并进行系统的整理与分析,回顾近10年来国内外基于深度学习的运动表现视频分析技术研究,包括深度学习算法、计算机视觉等在体育分析领域的应用现状,揭示深度学习在运动分析领域的潜在应用,探索深度学习作为分析体育运动的工具的潜力。目前在运动员及球跟踪、动作行为分析和表现评价方面,基于深度学习的分析方法已经表现出了良好的性能,未来拥有着巨大的发展潜力。展开更多
基金supported by the National Natural Science Foundation of China (Grant No. 40476039)
文摘Based on the general relationship described by Cheng between the drag coefficient and the Reynolds number of a particle, a new relationship between the Reynolds number and a dimensionless particle parameter is proposed. Using a trial-and-error procedure to minimize errors, the coefficients were determined and a formula was developed for predicting the settling velocity of natural sediment particles. This formula has higher prediction accuracy than other published formulas and it is applicable to all Reynolds numbers less than 2× 10^5.
基金Open Fund of Key Laboratory of Coastal Disasters and Defence (Ministry of Education)National Natural Science Foundation of China under contract No. 50779015
文摘In the present paper, by introducing the effective wave elevation, we transform the extended elliptic mild-slope equation with bottom friction, wave breaking and steep or rapidly varying bottom topography to the simplest time-dependent hyperbolic equation. Based on this equation and the empirical nonlinear amplitude dispersion relation proposed by Li et al. （2003）, the numerical scheme is established. Error analysis by Taylor expansion method shows that the numerical stability of the present model succeeds the merits in Song et al. （2007）＇s model because of the introduced dissipation terms. For the purpose of verifying its performance on wave nonlinearity, rapidly varying topography and wave breaking, the present model is applied to study： （1） wave refraction and diffraction over a submerged elliptic shoal on a slope （Berkhoff et al., 1982）; （2） Bragg reflection of monochromatic waves from the sinusoidal ripples （Davies and Heathershaw, 1985）; （3） wave transformation near a shore attached breakwater （Watanabe and Maruyama, 1986）. Comparisons of the numerical solutions with the experimental or theoretical ones or with those of other models （REF/DIF model and FUNWAVE model） show good results, which indicate that the present model is capable of giving favorably predictions of wave refraction, diffraction, reflection, shoaling, bottom friction, breaking energy dissipation and weak nonlinearity in the near shore zone.
基金The Ministry of Education Fundation for the Doctoral Program of Higher Education under contract No.200802940014the Natural Science Foundation of Hohai University under contract Nos 2008430511Ministry of Transport Open Fundation of Laboratry of port,waterway,sediment engineering
文摘Since the mild-slope equation was derived by Berkhoff （1972）,the researchers considered various mechanism to simplify and improve the equation,which has been widely used for coastal wave field calculation.Recently,some scholars applied the mild-slope equation in simulating the tidal motion,which proves that the equation is capable to calculate the tide in actual terrain.But in their studies,they made a lot of simplifications,and did not consider the effects of Coriolis force and bottom friction on tidal wave.In this paper,the first-order linear mild-slope equations are deduced from Kirby mild-slope equation including wave and current interaction.Then,referring to the method of wave equations’ modification,the Coriolis force and bottom friction term are considered,and the effects of which have been performed with the radial sand ridges topography.Finally,the results show that the modified mild-slope equation can be used to simulate tidal motion,and the calculations agree well with the measurements,thus the applicability and validity of the mild-slope equation on tidal simulation are further proved.
文摘随着人工智能技术的发展,深度学习在体育领域的研究与应用也在逐渐增多。将人工智能技术应用于竞技体育运动视频分析,既是国内外理论研究关注的热点,也是促进竞技体育高质量发展的有效手段。通过Google Scholar、中国知网、Web of Science及SPORTDiscus数据库检索文献,并进行系统的整理与分析,回顾近10年来国内外基于深度学习的运动表现视频分析技术研究,包括深度学习算法、计算机视觉等在体育分析领域的应用现状,揭示深度学习在运动分析领域的潜在应用,探索深度学习作为分析体育运动的工具的潜力。目前在运动员及球跟踪、动作行为分析和表现评价方面,基于深度学习的分析方法已经表现出了良好的性能,未来拥有着巨大的发展潜力。
