文章以统计过程控制理论(Statistical Process Control,SPC)为基础提出了一种张力腿平台甲板有效上浪高度计算模型,针对海浪波高是随机过程这一不确定因素导致的上浪波高没有确定解的情况,分析计算了波浪谱下的张力腿平台相对运动和有...文章以统计过程控制理论(Statistical Process Control,SPC)为基础提出了一种张力腿平台甲板有效上浪高度计算模型,针对海浪波高是随机过程这一不确定因素导致的上浪波高没有确定解的情况,分析计算了波浪谱下的张力腿平台相对运动和有效上浪波高,计算得到了有效上浪波高控制中心均值、下管制限值、上管制限值和相应发生概率。由相同波浪参数下不同波浪谱计算得到的有效上浪波高控制中心均值相同这一结论,发现波浪能量在不同谱之间的分布是相同的,说明波浪能量在时间维度、空间维度和频率维度的分布是一致的。在求解有效上浪波高控制中心均值时,提出了能更好刻画波高在波浪参数下的分布形式的面积均值法,并由此方法计算控制中心均值和上管制限值。以一型张力腿平台为例,针对波浪谱中超过某一发生概率的情况,运用统计过程控制理论和SPC控制图,计算了有效上浪波高控制中心均值、下管制限值和上管制限值,判断随机有效上浪波高是否处于统计控制状态,发现了波浪谱中的发生概率越大,随机有效上浪波高越可控这一规律。比较不同波浪入射角的有效上浪波高控制中心均值,发现了不同波浪入射角对有效上浪波高影响不大、发生概率对有效上浪波高影响较大的规律。最后基于统计过程控制理论计算得到整个有效上浪波高均值、发生概率、下管制限值和上管制限值。提出了在有效上浪波高均值和上管制限值之间结构物会受到交变载荷的作用容易疲劳损伤和腐蚀损伤的建议。结果表明该方法可以对张力腿平台有效上浪波高进行计算,并可推广应用于其它海上结构物的有效上浪波高计算。展开更多
A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was establ...A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was established on the basis of linear wave theory.The fundamental solution to the Helmholtz equation within an infinite strip area that explicitly satisfies two infinite parallel boundaries is used together with Radiation condition rather than the solution of an infinite area.According to the proposed theory and method,the computer programs have been composed in Visual C ++ Development Studio.Several examples show that the technique and its program are feasible and efficient.And the wave forces upon continuous cylinders can be decreased by as much as 14%～24% under a ratio of D/L= 0.09～0.19 compared with the square caissons.展开更多
Feiyantan was the discharge area of Diaokou River distributary of the Yellow River during the period of 1964 to 1976. The coastal erosion feature and morphological evolution at the Feiyantan coast are studied in the l...Feiyantan was the discharge area of Diaokou River distributary of the Yellow River during the period of 1964 to 1976. The coastal erosion feature and morphological evolution at the Feiyantan coast are studied in the light of the topography and section depth, and the corresponding dynamics of wave and current. Results indicate that the protruding topography left after the Diaokou River distributary was abandoned is the main cause of strong coastal erosion. Further research suggests that waves start up the sediment and the tidal current transports it, and the waves and tidal current are combined to be the dominant dynamic mechanism of coastal erosion, in which the tidal residual current takes and transports the sediment outward, thus causing the sediment to wane in the coast.展开更多
The importance of studying the behavior of the soil at the sea bottom under the action of wave force has arisen with the development of offshore engineering.In this paper,the behavior of the soft clay under the action...The importance of studying the behavior of the soil at the sea bottom under the action of wave force has arisen with the development of offshore engineering.In this paper,the behavior of the soft clay under the action of wave forces is studied by performing centrifugal tests.The soil profile and the wave characters were simulated in the centrifugal model cell according to the typical environmental conditions of the oil fields in the Bohai gulf.Test results show that the soft clay layer will be seriously softened near the upper surface under the maximum wave height and slightly affected in the deeper layer,and that no liquefaction was recorded in the silty sand sublayer during the test.It is proven that the centrifugal test is a valid technique for simulating the interaction between soil and wave.展开更多
Based on the fifth-order Stokes regular wave theory, a simplified model for extreme-wave kinematics in deep sea was developed. In this model, from the wave records the average of two neighboring wave periods for the e...Based on the fifth-order Stokes regular wave theory, a simplified model for extreme-wave kinematics in deep sea was developed. In this model, from the wave records the average of two neighboring wave periods for the extreme crest or trough was defined as the period of the Stokes wave by the up and down zero-crossing methods. Then the input wave amplitude was deduced by substituting the wave period and extreme crest or trough into the expression for the fifth-order Stokes wave elevation. Thus the corresponding formula for the wave velocity can be used to describe kinematics beneath the extreme wave. By comparison with the published numerical models and experimental data, the proposed model is validated to be able to calculate the extreme wave velocity rather easily and accurately.展开更多
An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,...An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,free surface and solid boundary in this paper.The characteristics of waves propagating over a step have been investigated by this numerical model.The breaker wave height is determined depending on the kinetic criterion.The numerical model is verified by laboratory experiments,and the empirical formula for the damping of wave height due to breaking is also given by experiments.展开更多
The influence of long regular waves on wind waves are examined in the laboratory tank. The wave spectra of wind waves are compared when there is and there is not long waves. Besides the widely addressed suppression of...The influence of long regular waves on wind waves are examined in the laboratory tank. The wave spectra of wind waves are compared when there is and there is not long waves. Besides the widely addressed suppression of wind waves by long waves, it is also found that, the presence of long regular wave induces low frequency shift of wind waves when long wave slope is small and also its frequencyf is quite apart from wind wave crest frequencies fp. The effect of long wave modulation on wind wave spectra is estimated according to Longuet-Higgins ＆ Stewart （1960） （abbreviated as LS60 afterwards）, which is found to be prominent at the large ratio of fp/f l. It＇s also found that, when the limitation of wave breaking on wind wave steepness is taken account of, the LS60 theory can explain the low frequency shift satisfactorily. The work suggests that, at small long wave slope and large ratio of fp/fl, the LS60 modulation mechanism together with the enhanced wave breaking may dominate the influence of long waves on wind waves.展开更多
Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptab...Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.展开更多
The wave-shaped space truss is used as the roof of the natatorium in Tianjin University,which ingeniously displays the function of the building.In this paper,the wave-shaped space truss is analyzed and designed,consid...The wave-shaped space truss is used as the roof of the natatorium in Tianjin University,which ingeniously displays the function of the building.In this paper,the wave-shaped space truss is analyzed and designed,considering the substructure made of reinforced concrete rigid frame and the space truss working together.Also,the anti-seismic characteristic of the wave-shaped space truss is studied based on the integral model.展开更多
Temperature front (TF) is one of the important features in the Yellow Sea, which forms in spring,thrives in summer, and fades in autumn as thermocline declines. TF intensity |ST| is defined to describe the distributio...Temperature front (TF) is one of the important features in the Yellow Sea, which forms in spring,thrives in summer, and fades in autumn as thermocline declines. TF intensity |ST| is defined to describe the distribution of TF. Based on the MASNUM wave-tide-circulation coupled model, temperature distribution in the Yellow Sea was simulated with and without tidal effects. Along 36°N, distribution of TF from the simulated results are compared with the observations, and a quantitative analysis is introduced to evaluate the tidal effects on the forming and maintaining processes of the TF. Tidal mixing and the circulation structure adapting to it are the main causes of the TF.展开更多
文摘文章以统计过程控制理论(Statistical Process Control,SPC)为基础提出了一种张力腿平台甲板有效上浪高度计算模型,针对海浪波高是随机过程这一不确定因素导致的上浪波高没有确定解的情况,分析计算了波浪谱下的张力腿平台相对运动和有效上浪波高,计算得到了有效上浪波高控制中心均值、下管制限值、上管制限值和相应发生概率。由相同波浪参数下不同波浪谱计算得到的有效上浪波高控制中心均值相同这一结论,发现波浪能量在不同谱之间的分布是相同的,说明波浪能量在时间维度、空间维度和频率维度的分布是一致的。在求解有效上浪波高控制中心均值时,提出了能更好刻画波高在波浪参数下的分布形式的面积均值法,并由此方法计算控制中心均值和上管制限值。以一型张力腿平台为例,针对波浪谱中超过某一发生概率的情况,运用统计过程控制理论和SPC控制图,计算了有效上浪波高控制中心均值、下管制限值和上管制限值,判断随机有效上浪波高是否处于统计控制状态,发现了波浪谱中的发生概率越大,随机有效上浪波高越可控这一规律。比较不同波浪入射角的有效上浪波高控制中心均值,发现了不同波浪入射角对有效上浪波高影响不大、发生概率对有效上浪波高影响较大的规律。最后基于统计过程控制理论计算得到整个有效上浪波高均值、发生概率、下管制限值和上管制限值。提出了在有效上浪波高均值和上管制限值之间结构物会受到交变载荷的作用容易疲劳损伤和腐蚀损伤的建议。结果表明该方法可以对张力腿平台有效上浪波高进行计算,并可推广应用于其它海上结构物的有效上浪波高计算。
基金Supported by National Natural Science Foundation of China(No.5990 90 0 5) National High Performance Computing Foundation of
文摘A numerical model of wave force upon continuous cylinder structures with a large diameter using the boundary element method (BEM) is presented. A numerical model of reflecting wave upon continuous cylinders was established on the basis of linear wave theory.The fundamental solution to the Helmholtz equation within an infinite strip area that explicitly satisfies two infinite parallel boundaries is used together with Radiation condition rather than the solution of an infinite area.According to the proposed theory and method,the computer programs have been composed in Visual C ++ Development Studio.Several examples show that the technique and its program are feasible and efficient.And the wave forces upon continuous cylinders can be decreased by as much as 14%～24% under a ratio of D/L= 0.09～0.19 compared with the square caissons.
文摘Feiyantan was the discharge area of Diaokou River distributary of the Yellow River during the period of 1964 to 1976. The coastal erosion feature and morphological evolution at the Feiyantan coast are studied in the light of the topography and section depth, and the corresponding dynamics of wave and current. Results indicate that the protruding topography left after the Diaokou River distributary was abandoned is the main cause of strong coastal erosion. Further research suggests that waves start up the sediment and the tidal current transports it, and the waves and tidal current are combined to be the dominant dynamic mechanism of coastal erosion, in which the tidal residual current takes and transports the sediment outward, thus causing the sediment to wane in the coast.
文摘The importance of studying the behavior of the soil at the sea bottom under the action of wave force has arisen with the development of offshore engineering.In this paper,the behavior of the soft clay under the action of wave forces is studied by performing centrifugal tests.The soil profile and the wave characters were simulated in the centrifugal model cell according to the typical environmental conditions of the oil fields in the Bohai gulf.Test results show that the soft clay layer will be seriously softened near the upper surface under the maximum wave height and slightly affected in the deeper layer,and that no liquefaction was recorded in the silty sand sublayer during the test.It is proven that the centrifugal test is a valid technique for simulating the interaction between soil and wave.
基金Supported by the NSFC (under Grant Nos.5070900 and 10772040)the National High Tech Research and Development Program of China (2006AA09A109-3)
文摘Based on the fifth-order Stokes regular wave theory, a simplified model for extreme-wave kinematics in deep sea was developed. In this model, from the wave records the average of two neighboring wave periods for the extreme crest or trough was defined as the period of the Stokes wave by the up and down zero-crossing methods. Then the input wave amplitude was deduced by substituting the wave period and extreme crest or trough into the expression for the fifth-order Stokes wave elevation. Thus the corresponding formula for the wave velocity can be used to describe kinematics beneath the extreme wave. By comparison with the published numerical models and experimental data, the proposed model is validated to be able to calculate the extreme wave velocity rather easily and accurately.
文摘An idealized numerical wave flume has been established by finite element method on the bases of Navier Stokes equations through prescribing the appropriate boundary conditions for the open boundary,incident boundary,free surface and solid boundary in this paper.The characteristics of waves propagating over a step have been investigated by this numerical model.The breaker wave height is determined depending on the kinetic criterion.The numerical model is verified by laboratory experiments,and the empirical formula for the damping of wave height due to breaking is also given by experiments.
文摘The influence of long regular waves on wind waves are examined in the laboratory tank. The wave spectra of wind waves are compared when there is and there is not long waves. Besides the widely addressed suppression of wind waves by long waves, it is also found that, the presence of long regular wave induces low frequency shift of wind waves when long wave slope is small and also its frequencyf is quite apart from wind wave crest frequencies fp. The effect of long wave modulation on wind wave spectra is estimated according to Longuet-Higgins ＆ Stewart （1960） （abbreviated as LS60 afterwards）, which is found to be prominent at the large ratio of fp/f l. It＇s also found that, when the limitation of wave breaking on wind wave steepness is taken account of, the LS60 theory can explain the low frequency shift satisfactorily. The work suggests that, at small long wave slope and large ratio of fp/fl, the LS60 modulation mechanism together with the enhanced wave breaking may dominate the influence of long waves on wind waves.
基金supports from National Natural Science Foundation of China (No. 41406032 and No. 41376014)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics (No. SOED1305)
文摘Ocean waves are the core environmental elements affecting the movements and structure design of ships. Statistical analysis of wave parameters is the basis for the establishment of long-term ship environmental adaptability prediction model. The observations from coastal stations, buoys, altimeters and volunteer ships that cover from 1993 to 2011 were interpolated into miller Ion-lat grids by using bilinear method and the analytical fields of ocean waves were given. By using optimal interpolation, the analysis wave fields were assimilated into the WAVEWATCH III （WW3） simulation results. From the assimilated results, the wave rose statistics, the wave height of muitiyear return period and the extreme 2-D wave spectrum are related to the ship seakeeping were calculated. Finally, the wave statistics in China offshore were analyzed in detail.
文摘The wave-shaped space truss is used as the roof of the natatorium in Tianjin University,which ingeniously displays the function of the building.In this paper,the wave-shaped space truss is analyzed and designed,considering the substructure made of reinforced concrete rigid frame and the space truss working together.Also,the anti-seismic characteristic of the wave-shaped space truss is studied based on the integral model.
文摘Temperature front (TF) is one of the important features in the Yellow Sea, which forms in spring,thrives in summer, and fades in autumn as thermocline declines. TF intensity |ST| is defined to describe the distribution of TF. Based on the MASNUM wave-tide-circulation coupled model, temperature distribution in the Yellow Sea was simulated with and without tidal effects. Along 36°N, distribution of TF from the simulated results are compared with the observations, and a quantitative analysis is introduced to evaluate the tidal effects on the forming and maintaining processes of the TF. Tidal mixing and the circulation structure adapting to it are the main causes of the TF.
