This study examines the reflection of regular and irregular waves from a partially perforated caisson breakwater located on a step bed. The step bed is treated as an idealized rubble mound foundation. Based on the lin...This study examines the reflection of regular and irregular waves from a partially perforated caisson breakwater located on a step bed. The step bed is treated as an idealized rubble mound foundation. Based on the linear potential theory, an analytical solution is developed to calculate the reflection coefficient of the structure subjected to regular waves. The matched eigenfunction expansion method is used for the solution. The regular wave method is also extended to irregular waves using a linear transfer function. The calculated results obtained for limiting cases are exactly the same as corresponding results given by the previous researchers. The present predictions also agree well with experimental data in the published literatures. Numerical experiments are conducted to examine the variations of the reflection coefficient versus its main effect factors, and some interesting results are presented.展开更多
On the basis of a potential theory and Euler-Bernoulli beam theory, an analytical solution for oblique wave scattering by a semi-infinite elastic plate with finite draft floating on a step topography is developed usin...On the basis of a potential theory and Euler-Bernoulli beam theory, an analytical solution for oblique wave scattering by a semi-infinite elastic plate with finite draft floating on a step topography is developed using matched eigenfunction expansions. Different from previous studies, the effects of a wave incident angle, a plate draft, three different plate edge conditions （free, simply supported and built-in） and a sea-bottom topography are all taken into account. Moreover, the plate edge conditions are directly incorporated into linear algebraic equations for determining unknown expansion coefficients in velocity potentials, which leads to a simple and efficient solving procedure. Numerical results show that the convergence of the present solution is good, and an energy conservation relation is well satisfied. Also, the present predictions are in good agreement with known results for special cases. The effects of the wave incident angle, the plate draft, the plate edge conditions and the sea-bottom topography on various hydrodynamic quantities are analyzed. Some useful results are presented for engineering designs.展开更多
The reflection and transmission of the level step to the water waves in the linear and continuous layer liquid were studied in this paper. Based on the matching method of the eigenfunction and a Boussinesq approximati...The reflection and transmission of the level step to the water waves in the linear and continuous layer liquid were studied in this paper. Based on the matching method of the eigenfunction and a Boussinesq approximation, the analytical expression of the diffraction was obtained and the computing methods of the reflection and transmission en- ergy of the level step were proposed. For the incident wave with a frequency greater than that of the flotage, there is only one mode of plane traveling wave in the flow field. In the range of this greater frequency, the linear and continuous delamination effect will affect the reflection and transmission energy of the floating rectangular box. When the fre- quency of the incident wave is less than the flotage frequency, the energy of the plane traveling wave with infinite modes in the flow field will change into the energy of different modes for each incident wave of different modes.展开更多
Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and o...Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and obtain its range and micro-motion frequency is proposed in which multiple periods stepped-frequency continuous-wave signal and Moving Target Indication (MTI) filter are adopted. The simulation results illustrate the validity of this method and present the detection of the target range and the vibration frequency. The experiment gives promising results.展开更多
As a new method, the Level Set method had been developed to compute the interface of two-phase flow. The basic mathematical theory and the detailed method to solve the free surface hydrodynamic problem had been invest...As a new method, the Level Set method had been developed to compute the interface of two-phase flow. The basic mathematical theory and the detailed method to solve the free surface hydrodynamic problem had been investigated. By using the Level Set method, the transformation of a solitary wave over a front step was simulated. The results were in good agreement with laboratory experiments.展开更多
倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟...倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟随多孔的结构然后跟随多孔的结构的无界的水媒介的一种特殊情况的水媒介从多孔的结构在有限距离放的第一面一稳固的垂直的墙。在两个盒子中，边界价值问题在三不同媒介被建立，是的第一媒介水，是的第二媒介由 p 组成的多孔的结构在每个步骤上面的垂直区域一个和是的第三媒介水再。由沿着 virtualvertical 边界使用匹配的条件，线性方程的一个系统被推出。思考系数和播送进步波浪的无尺寸的振幅的行为由于不同相关参数被学习。由于倾斜的水的繁殖，通过多孔的结构的波浪也是的精力损失执行了。各种各样的参数的效果例如迅速凋落的模式的数字，孔，磨擦因素，结构宽度，步骤和入射角的数字，在思考以后，系数和播送波浪的无尺寸的振幅为两个盒子图形地被学习。迅速凋落的模式的数字仅仅影响散布现象。但是孔表演的更高的价值相对为更低的孔比那降低思考。在思考系数的摆动为磨擦因素的更低的价值被观察，但是它随磨擦因素的价值的增加消失。播送进步波浪的振幅独立于结构的孔。但是磨擦因素的更低的价值引起更高的传动。调查然后为第二个盒子被执行，即，当墙是不在的时。这里考虑的二个盒子之间的重要差别是思考由于薄多孔的结构很高稳固的墙什么时候作为与盒子相比存在没有墙什么时候是在场的。精力损失也由于不同的孔，磨擦因素，结构宽度和入射角被检验。我们的模型的有效性被与可得到的匹配它查明。展开更多
Based on linear water-wave theory, this study investigated the scattering of oblique incident water waves by two unequal surface-piercing thin vertical rigid plates with stepped bottom topography. By using the matched...Based on linear water-wave theory, this study investigated the scattering of oblique incident water waves by two unequal surface-piercing thin vertical rigid plates with stepped bottom topography. By using the matched eigenfunction expansion method and a least square approach, the analytical solutions are sought for the established boundary value problem. The effects of the incidence angle, location of step, depth ratio of deep to shallow waters,and column width between two plates, on the reflection coefficients, the horizontal wave forces acting on the two plates, and the mean surface elevation between the two plates, are numerically examined under a variety of wave conditions. The results show that the existence of the stepped bottom between two plates considerably impacts the hydrodynamic performances of the present system. It is found that the effect of stepped bottom on the reflection coefficient of the present two-plate structure is evident only with waves of the low dimensionless frequency.Moreover, the influence of the step location on the hydrodynamic performance of the present two-plate structure is slight if the step is placed in between the two plates.展开更多
The propagation along oz of pulsed sound waves made of sequences of elementary unit pulses U (sin τ) where U is the unit step function and τ = kz -ωt is analyzed using the expansion of U (sin τ) and of the Dirac d...The propagation along oz of pulsed sound waves made of sequences of elementary unit pulses U (sin τ) where U is the unit step function and τ = kz -ωt is analyzed using the expansion of U (sin τ) and of the Dirac distribution δ (sin τ) in terms of τ-nπ where n is an integer. Their properties and how these pulsed sound waves could be generated are discussed.展开更多
-This paper introduces the main points of design and operation features of a curved combinative breakwater wall which can not only resist storm surge but also roll wave back and which has the functions of seawall, tid...-This paper introduces the main points of design and operation features of a curved combinative breakwater wall which can not only resist storm surge but also roll wave back and which has the functions of seawall, tide protection, anti-wave, land development, traffic and tourism. The new kind of breakwater optimized by wave model test has been utilized in the seawall in the coast regulation project in Zhanjiang City, and good results have been achieved.展开更多
A three-step finite element method (FEM) together with Large Eddy Simulation (LES) is applied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers. Both two dimensional and thre...A three-step finite element method (FEM) together with Large Eddy Simulation (LES) is applied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers. Both two dimensional and three-dimensional numerical simulation is carried out to determine the three-dimensional effect. The results of numerical simulation agree quite well with the wave forces acting on pipeline models measured in physical model test.展开更多
基金The Natural Science Foundation of Shandong Province under contract No Q2008F01the Specialized Research Fund for the Doctoral Program of Higher Education under contract No 200804231006the National Natural Science Foundation of China under contract Nos 40876047 and 50609001
文摘This study examines the reflection of regular and irregular waves from a partially perforated caisson breakwater located on a step bed. The step bed is treated as an idealized rubble mound foundation. Based on the linear potential theory, an analytical solution is developed to calculate the reflection coefficient of the structure subjected to regular waves. The matched eigenfunction expansion method is used for the solution. The regular wave method is also extended to irregular waves using a linear transfer function. The calculated results obtained for limiting cases are exactly the same as corresponding results given by the previous researchers. The present predictions also agree well with experimental data in the published literatures. Numerical experiments are conducted to examine the variations of the reflection coefficient versus its main effect factors, and some interesting results are presented.
基金The National Natural Science Foundation of China under contract Nos 51490675,51322903 and 51279224
文摘On the basis of a potential theory and Euler-Bernoulli beam theory, an analytical solution for oblique wave scattering by a semi-infinite elastic plate with finite draft floating on a step topography is developed using matched eigenfunction expansions. Different from previous studies, the effects of a wave incident angle, a plate draft, three different plate edge conditions （free, simply supported and built-in） and a sea-bottom topography are all taken into account. Moreover, the plate edge conditions are directly incorporated into linear algebraic equations for determining unknown expansion coefficients in velocity potentials, which leads to a simple and efficient solving procedure. Numerical results show that the convergence of the present solution is good, and an energy conservation relation is well satisfied. Also, the present predictions are in good agreement with known results for special cases. The effects of the wave incident angle, the plate draft, the plate edge conditions and the sea-bottom topography on various hydrodynamic quantities are analyzed. Some useful results are presented for engineering designs.
文摘The reflection and transmission of the level step to the water waves in the linear and continuous layer liquid were studied in this paper. Based on the matching method of the eigenfunction and a Boussinesq approximation, the analytical expression of the diffraction was obtained and the computing methods of the reflection and transmission en- ergy of the level step were proposed. For the incident wave with a frequency greater than that of the flotage, there is only one mode of plane traveling wave in the flow field. In the range of this greater frequency, the linear and continuous delamination effect will affect the reflection and transmission energy of the floating rectangular box. When the fre- quency of the incident wave is less than the flotage frequency, the energy of the plane traveling wave with infinite modes in the flow field will change into the energy of different modes for each incident wave of different modes.
文摘Mechanical micro-vibration of a target may induce phase modulations on the radar echo,and the vibration can be detected to identify micro-motion target. In this paper,a new method to detect a micro-motion target and obtain its range and micro-motion frequency is proposed in which multiple periods stepped-frequency continuous-wave signal and Moving Target Indication (MTI) filter are adopted. The simulation results illustrate the validity of this method and present the detection of the target range and the vibration frequency. The experiment gives promising results.
文摘As a new method, the Level Set method had been developed to compute the interface of two-phase flow. The basic mathematical theory and the detailed method to solve the free surface hydrodynamic problem had been investigated. By using the Level Set method, the transformation of a solitary wave over a front step was simulated. The results were in good agreement with laboratory experiments.
文摘倾斜的海浪由放在多步底部地形学上的垂直多孔的结构抑制在线性水波浪理论的帮助下被学习。倾斜的波浪的某部分，多孔的结构上的事件，变得被多步底部反映了，多孔的结构，和剩余的宣传进跟随多孔的结构的水媒介。二个盒子被考虑：在跟随多孔的结构然后跟随多孔的结构的无界的水媒介的一种特殊情况的水媒介从多孔的结构在有限距离放的第一面一稳固的垂直的墙。在两个盒子中，边界价值问题在三不同媒介被建立，是的第一媒介水，是的第二媒介由 p 组成的多孔的结构在每个步骤上面的垂直区域一个和是的第三媒介水再。由沿着 virtualvertical 边界使用匹配的条件，线性方程的一个系统被推出。思考系数和播送进步波浪的无尺寸的振幅的行为由于不同相关参数被学习。由于倾斜的水的繁殖，通过多孔的结构的波浪也是的精力损失执行了。各种各样的参数的效果例如迅速凋落的模式的数字，孔，磨擦因素，结构宽度，步骤和入射角的数字，在思考以后，系数和播送波浪的无尺寸的振幅为两个盒子图形地被学习。迅速凋落的模式的数字仅仅影响散布现象。但是孔表演的更高的价值相对为更低的孔比那降低思考。在思考系数的摆动为磨擦因素的更低的价值被观察，但是它随磨擦因素的价值的增加消失。播送进步波浪的振幅独立于结构的孔。但是磨擦因素的更低的价值引起更高的传动。调查然后为第二个盒子被执行，即，当墙是不在的时。这里考虑的二个盒子之间的重要差别是思考由于薄多孔的结构很高稳固的墙什么时候作为与盒子相比存在没有墙什么时候是在场的。精力损失也由于不同的孔，磨擦因素，结构宽度和入射角被检验。我们的模型的有效性被与可得到的匹配它查明。
基金financially supported by the National Natural Science Foundation of China(Grant No.11702244)the Project of the Cooperation of Zhoushan City and Zhejiang University(Grant No.2017C82223)+1 种基金the Open Foundation of Key Laboratory of Port,Waterway and Sedimentation Engineering of the Ministry of Transport(Grant No.Yn216006)the Fundamental Research Funds for the Central Universities(WUT:2017IVA009)
文摘Based on linear water-wave theory, this study investigated the scattering of oblique incident water waves by two unequal surface-piercing thin vertical rigid plates with stepped bottom topography. By using the matched eigenfunction expansion method and a least square approach, the analytical solutions are sought for the established boundary value problem. The effects of the incidence angle, location of step, depth ratio of deep to shallow waters,and column width between two plates, on the reflection coefficients, the horizontal wave forces acting on the two plates, and the mean surface elevation between the two plates, are numerically examined under a variety of wave conditions. The results show that the existence of the stepped bottom between two plates considerably impacts the hydrodynamic performances of the present system. It is found that the effect of stepped bottom on the reflection coefficient of the present two-plate structure is evident only with waves of the low dimensionless frequency.Moreover, the influence of the step location on the hydrodynamic performance of the present two-plate structure is slight if the step is placed in between the two plates.
文摘The propagation along oz of pulsed sound waves made of sequences of elementary unit pulses U (sin τ) where U is the unit step function and τ = kz -ωt is analyzed using the expansion of U (sin τ) and of the Dirac distribution δ (sin τ) in terms of τ-nπ where n is an integer. Their properties and how these pulsed sound waves could be generated are discussed.
文摘-This paper introduces the main points of design and operation features of a curved combinative breakwater wall which can not only resist storm surge but also roll wave back and which has the functions of seawall, tide protection, anti-wave, land development, traffic and tourism. The new kind of breakwater optimized by wave model test has been utilized in the seawall in the coast regulation project in Zhanjiang City, and good results have been achieved.
基金Part of results of a project financially supported by the State Key Laboratory of Coastal and Offshore Engineering of Dalian University of Technology
文摘A three-step finite element method (FEM) together with Large Eddy Simulation (LES) is applied to incompressible turbulent flow around seabed pipelines at relatively high Reynolds numbers. Both two dimensional and three-dimensional numerical simulation is carried out to determine the three-dimensional effect. The results of numerical simulation agree quite well with the wave forces acting on pipeline models measured in physical model test.
