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A Monitoring Method for Transmission Tower Foots Displacement Based on Wind-Induced Vibration Response
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作者 Zhicheng Liu Long Zhao +2 位作者 Guanru Wen Peng Yuan Qiu Jin 《Structural Durability & Health Monitoring》 EI 2023年第6期541-555,共15页
The displacement of transmission tower feet can seriously affect the safe operation of the tower,and the accuracy of structural health monitoring methods is limited at the present stage.The application of deep learnin... The displacement of transmission tower feet can seriously affect the safe operation of the tower,and the accuracy of structural health monitoring methods is limited at the present stage.The application of deep learning method provides new ideas for structural health monitoring of towers,but the current amount of tower vibration fault data is restricted to provide adequate training data for Deep Learning(DL).In this paper,we propose a DT-DL based tower foot displacement monitoring method,which firstly simulates the wind-induced vibration response data of the tower under each fault condition by finite element method.Then the vibration signal visualization and Data Transfer(DT)are used to add tower fault data samples to solve the problem of insufficient actual data quantity.Subsequently,the dynamic response test is carried out under different tower fault states,and the tower fault monitoring is carried out by the DL method.Finally,the proposed method is compared with the traditional online monitoring method,and it is found that this method can significantly improve the rate of convergence and recognition accuracy in the recognition process.The results show that the method can effectively identify the tower foot displacement state,which can greatly reduce the accidents that occurred due to the tower foot displacement. 展开更多
关键词 Tower online monitoring wind-induced response continuous wavelet transform CNN multi sensor information fusion
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Research on wind-induced responses of a large-scale membrane structure 被引量:4
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作者 Zhou Xuanyi Han Zhihui +3 位作者 Gu Ming Zhang An-an Zhang Weiyu Fang Wei 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2013年第2期297-305,共9页
The wind-induced responses of a large-scale membrane structure, Expo Boulevard, are evaluated in this study. To obtain the wind pressure distribution on the roof surface, a wind tunnel test is performed. A brief analy... The wind-induced responses of a large-scale membrane structure, Expo Boulevard, are evaluated in this study. To obtain the wind pressure distribution on the roof surface, a wind tunnel test is performed. A brief analysis of wind pressure on the membrane roof is conducted first and then an analysis of the wind-induced responses of the structure is carried out using a numerical integral method in the time domain. In the process of calculation, the geometrical nonlinearity is taken into account. Results indicate that mean, RSM and peak values of the structure responses increase nonlinearly while the approaching flow velocity increases. Strong nonlinear characteristics are observed in the displacement responses, whereas the responses of nodal stress and cable axial force show minimal nonlinear properties when the membrane structure is subjected to wind loads. Different values of the damping ratio only have a minimal impact on the RSM response of the structure because the background component is a dominant part of the total dynamic response and the resonant component is too small. As the damping ratio increases from 0.02 to 0.05, the RMS responses of vertical displacement, nodal stress and cable axial force decrease by 8.1%, 6.7% and 17.9%, respectively. Since the mean component plays a significant role in the wind-induced response, the values of the gust response factor are not high for Expo Boulevard. 展开更多
关键词 wind tunnel test wind-induced response time domain method geometrical nonlinear analysis
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Wind-induced responses of super-large cooling towers 被引量:3
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作者 柯世堂 葛耀君 +2 位作者 赵林 陈少林 Y.Tamura 《Journal of Central South University》 SCIE EI CAS 2013年第11期3216-3228,共13页
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
关键词 super-large cooling towers wind-induced responses wind vibration coefficients aero-elastic model consistent coupled method
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Effects of high modes on the wind-induced response of super high-rise buildings 被引量:2
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作者 Feng Ruoqiang Guirong Yan Ge Jinming 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2012年第3期427-434,共8页
For super high-rise buildings, the vibration period of the basic mode is several seconds, and it is very close to the period of the fluctuating wind. The damping of super high-rise buildings is low, so super high-rise... For super high-rise buildings, the vibration period of the basic mode is several seconds, and it is very close to the period of the fluctuating wind. The damping of super high-rise buildings is low, so super high-rise buildings are very sensitive to fluctuating wind. The wind load is one of the key loads in the design of super high-rise buildings. It is known that only the basic mode is needed in the wind-response analysis of tall buildings. However, for super high-rise buildings, especially for the acceleration response, because of the frequency amplification of the high modes, the high modes and the mode coupling may need to be considered. Three typical super high-rise projects with the SMPSS in wind tunnel tests and the random vibration theory method were used to analyze the effect of high modes on the wind-induced response. The conclusions can be drawn as follows. First, for the displacement response, the basic mode is dominant, and the high modes can be neglected. Second, for the acceleration response, the high modes and the mode coupling should be considered. Lastly, the strain energy of modes can only give the vibration energy distribution of the high-rise building, and it cannot describe the local wind-induced vibration of high-rise buildings, especially for the top acceleration response. 展开更多
关键词 super high-rise building wind tunnel test mode couple wind-induced response
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Wind-induced vibration control of bridges using liquid column damper 被引量:3
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作者 薛素铎 高赞明 徐幼麟 《Earthquake Engineering and Engineering Vibration》 SCIE EI CSCD 2002年第2期271-280,共10页
The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper.By installing the TLCD in the bridge deck,a mathematical model for t... The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper.By installing the TLCD in the bridge deck,a mathematical model for the bridge-TLCD system is established.The governing equations of the system are developed by considering all three displacement components of the deck in vertical,lateral,and torsional vibrations,in which the interactions between the bridge deck,the TLCD,the aeroelastic forces,and the aerodynamic forces are fully reflected.Both buffeting and flutter analyses are carried out.The buffeting analysis is performed through random vibration approach,and a critical flutter condition is identified from flutter analysis.A numerical example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective device for suppressing wind-induced vibration of long span bridges,either for reducing the buffeting response or increasing the critical flutter wind velocity of the bridge. 展开更多
关键词 long span bridge bridge deck wind-induced vibration vibration control FLUTTER BUFFETING tuned liquid column damper TLCD-bridge interaction mathematical model
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Wind-induced response analysis of conical membrane structures 被引量:2
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作者 陈波 武岳 沈世钊 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第5期481-487,共7页
Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis ... Conical membrane structures are a typical form of tensile membrane structures. In the past, most studies focused on the static performance, but few on dynamic performance. In this paper, systematic parameter analysis of wind-induced response of conical membrane structures has been performed with nonlinear random simulation method in a time domain, by considering some parameters, such as span, rise-span ratio, prestress of membrane, and characteristic of the approaching wind flow. Moreover, formulas of the dynamic coefficient and nonlinear adjustment factor are advised, which can be conveniently used in wind-resistant design of conical membrane structures. 展开更多
关键词 conical membrane structures wind-induced response the dynamic coefficient nonlinear adjustment factor
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Wind-Induced Response Characteristics of a Tall Building from GPS and Accelerometer Measurements 被引量:3
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作者 Cuilin Kuang Kenny Chung Sau Kwok +1 位作者 Peter Andrew Hitchcock Xiaoli Ding 《Positioning》 2011年第1期1-13,共13页
The main objectives of the research are to characterize the wind-induced resonant and slowly-varying (quasi-static) responses of a tall building under ambient wind excitations based on GPS measurements. The equipment ... The main objectives of the research are to characterize the wind-induced resonant and slowly-varying (quasi-static) responses of a tall building under ambient wind excitations based on GPS measurements. The equipment used includes two sets of orthogonally aligned accelerometers, two GPS receivers and an ultrasonic anemometer. The natural frequencies of the wind-induced vibration of the tall building are determined by carrying out spectral analysis of the measured time series of acceleration. The time series are also used to estimate the structural damping with the random decrement technique (RDT). The results show that GPS can be effectively used to measure the resonant and slowly-varying responses of tall buildings with 3D mode shapes under wind excitations. The results from the GPS and the accelerometers agree well with each other in both the time and frequency domains. 展开更多
关键词 GPS MEASUREMENTS ACCELERATION wind-induced RESPONSE Tall BUILDING
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Wind-Induced Vibration Control for Substation Frame on Viscous Damper 被引量:1
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作者 Bingji Lan Kanghao Yan 《Computers, Materials & Continua》 SCIE EI 2020年第3期1303-1315,共13页
In order to study the wind-induced vibration control effect of the viscous damper on the large-scale substation frame,this paper takes the large-scale 1000 kV substation frame of western Inner Mongolia as an example.T... In order to study the wind-induced vibration control effect of the viscous damper on the large-scale substation frame,this paper takes the large-scale 1000 kV substation frame of western Inner Mongolia as an example.The time-history sample of pulsating wind load is simulated by harmonic superposition method based on Matlab software.6 kinds of viscous damper arrangement schemes have been designed,and SAP2000 finite element software is used for fine modeling and input wind speed time history load for nonlinear time history analysis.The displacement and acceleration of a typical node are the indicators of wind vibration control.The wind-induced vibration control effects of different schemes under different damping parameters have compared,and the damping parameters are analyzed for the optimal layout scheme.The results show that a viscous damper has installed in the lower layers of the substation;a viscous damper is placed between the ground column and the lattice beam.It is an integrated optimal solution.The wind-induced vibration control effect of the optimal scheme is sensitive to the viscous damper parameters,and the control effect does not increase linearly with the increase of the damping index and the damping coefficient.Corresponding to different damping indexes,the damping coefficient has a better range of values. 展开更多
关键词 Viscous damper wind-induced vibration control arrangement plan damping coefficient damping index
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Wind-induced vibration control of long-span power transmission towers 被引量:1
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作者 尹鹏 《Journal of Chongqing University》 CAS 2009年第2期112-124,共13页
We investigated wind-induced vibration control of long-span power transmission towers based on a case study of the Jingdongnan-Nanyang-Jingmen 1 000 kV transmission line project in P. R. China. The height of the cup t... We investigated wind-induced vibration control of long-span power transmission towers based on a case study of the Jingdongnan-Nanyang-Jingmen 1 000 kV transmission line project in P. R. China. The height of the cup tower is 181 m with a ground elevation of 47 m, which makes it a super flexible and wind-sensitive structure. Therefore, we should analyze the wind- resistant capacity of the system. We simulated applicable transverse fluctuating wind velocity field, developed a lead-rubber damper (LRD) for controlling wind-induced vibration of long-span transmission towers, deduced LRD calculation model parameter, and researched the best layout scheme and installation method of LRD. To calculate the wind-induced response of tower-line coupling system in seven layout schemes, we used the time history analysis method, and obtained the efficiencies of wind-induced vibration control. LRD deformation research proved that the damp of all LRDs was efficient under the designed wind velocity when they were laid along the edge of tower heads. We studied the controlling efficiency resulting fTom only applying stiffness to the tower polos where the dampers used to be laid under the designed wind velocity. The results show that the controlling efficiency was not ideal when the stiffness is increased on the poles only. Therefore, LRD should conlxibute to both the stiffness and damp of a structure to effectively reduce the dynamic response of a tower-line coupling system under strong winds. We also discussed the controlling efficiency of LRD under static winds. The results show that there was little difference between displacements derived by the finite clement time history method and those obtained by static wind method conducted by a design institute. This means the simulation on space relevant wind velocity field was accurate and reasonable. 展开更多
关键词 transmission towers lead-rubber damper wind-induced vibration control
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Dynamic Characteristics Analysis of Ice-Adhesion Transmission Tower-Line System under Effect of Wind-Induced Ice Shedding 被引量:1
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作者 Yongping Yu Lihui Chen +1 位作者 JuanjuanWang Guoji Liu 《Computer Modeling in Engineering & Sciences》 SCIE EI 2020年第11期647-670,共24页
The tower line system will be in an unsafe status due to uniform or uneven fall of ice coating which is attached to the surface of tower and lines.The fall of ice could be caused by wind action or thermal force.In ord... The tower line system will be in an unsafe status due to uniform or uneven fall of ice coating which is attached to the surface of tower and lines.The fall of ice could be caused by wind action or thermal force.In order to study the dynamic characteristics of the self-failure of the transmission line under the action of dynamicwind load,a finite elementmodel of the two-span transmission tower line system was established.The birth and death element methods are used to simulate the icing and shedding of the line.Tensile failure strength is the shedding criterion for ice coating.The fluctuating wind speed time history of the tower line systemis first simulated,and then the fluctuating wind and the average wind are superimposed to generate the instantaneous wind speed and converted into wind load.The dynamic response of the transmission tower line systemunder iced coupling with different wind speeds and different thicknesses of ice coating was studied.This is the first attempt that the coupling dynamic response of the icing shedding and wind load for the transmission tower-line system is discussed in this paper.In addition,the dynamic characteristics of wind are included.In particular,the limiting mechanical conditions are considered.According to the simulation results,it is found:because of the ice shedding,the stress of the conductor changes obviously in the first 20 seconds,and the ground wire changes sharply in the first two seconds;the icing of the conductor(ground)wire is gradually deicing under the action of wind vibration;the displacement of tower top increases with the increase of wind speed and icing thickness. 展开更多
关键词 Tower line system fluctuating wind ice shedding dynamic response wind-induced ice shedding
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Observation and modeling of tide- and wind-induced surface currents in Galway Bay 被引量:1
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作者 Lei Ren Stephen Nash Michael Hartnett 《Water Science and Engineering》 EI CAS CSCD 2015年第4期345-352,共8页
A high-frequency radar system has been deployed in Galway Bay, a semi-enclosed bay on the west coast of Ireland. The system provides surface currents with fine spatial resolution every hour. Prior to its use for model... A high-frequency radar system has been deployed in Galway Bay, a semi-enclosed bay on the west coast of Ireland. The system provides surface currents with fine spatial resolution every hour. Prior to its use for model validation, the accuracy of the radar data was verified through comparison with measurements from acoustic Doppler current profilers (ADCPs) and a good correlation between time series of surface current speeds and directions obtained from radar data and ADCP data. Since Galway Bay is located on the coast of the Atlantic Ocean, it is subject to relatively windy conditions, and surface currents are therefore strongly wind-driven. With a view to assimilating the radar data for forecasting purposes, a three-dimensional numerical model of Galway Bay, the Environmental Fluid Dynamics Code (EFDC), was developed based on a terrain-following vertical (sigma) coordinate system. This study shows that the performance and accuracy of the numerical model, particularly with regard to tide- and wind-induced surface currents, are sensitive to the vertical layer structure. Results of five models with different layer structures are presented and compared with radar measurements. A variable vertical structure with thin layers at the bottom and the surface and thicker layers in the middle of the water column was found to be the optimal layer structure for reproduction of tideand wind-induced surface currents. This structure ensures that wind shear can properly propagate from the surface layer to the sub-surface layers, thereby ensuring that wind forcing is not overdamped by tidal forcing. The vertical layer structure affects not only the velocities at the surface layer but also the velocities further down in the water column. 展开更多
关键词 wind-induced surface current Vertical layer structure High-frequency radar Coastal ocean dynamics application radar Environmental fluid dynamicscode Galway Bay
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Wind-induced vibration of single-layer reticulated shell structures
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作者 张建胜 武岳 沈世钊 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2008年第4期494-498,共5页
Aiming at the dynamic response of reticulated shell structures under wind load,systematic parameter analyses on wind-induced responses of Kiewitt6-6 type single-layer spherical reticulated shell structures and three-w... Aiming at the dynamic response of reticulated shell structures under wind load,systematic parameter analyses on wind-induced responses of Kiewitt6-6 type single-layer spherical reticulated shell structures and three-way grid single-layer cylindrical reticulated shell structures were performed with the random simulation method in time domain,including geometric parameters,structural parameters and aerodynamic parameters.Moreover,a wind-induced vibration coefficient was obtained,which can be a reference to the wind-resistance design of reticulated shell structures.The results indicate that the geometric parameters are the most important factor influencing wind-induced responses of the reticulated shell structures;the wind-induced vibration coeffi-cient is 3.0-3.2 for the spherical reticulated shell structures and that is 2.8-3.0 for the cylindrical reticula-ted shell structures,which shows that the wind-induced vibration coefficients of these two kinds of space frames are well-proportioned. 展开更多
关键词 reticulated shell structures wind-induced response random simulation method in time domain wind-induced vibration coefficient
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A Process Study of the Wind-Induced Circulation in the Persian Gulf
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作者 Stéphane Pous Xavier Carton Pascal Lazure 《Open Journal of Marine Science》 2013年第1期1-11,共11页
A shallow-water model, coupled with a three dimensional, hydrostatic ocean model, is used to study the wind induced circulation, and the Shatt-al-Arab river plume expansion, in the Persian Gulf. The models are used in... A shallow-water model, coupled with a three dimensional, hydrostatic ocean model, is used to study the wind induced circulation, and the Shatt-al-Arab river plume expansion, in the Persian Gulf. The models are used in an idealized configuration. The following results are obtained: 1) with northwesterly winds, a double gyre is formed: this gyre is cyclonic in the south and anticyclonic in the north. Southeastward currents flow along the Iranian and Arabian coast where the wind stress at the surface dominates the pressure gradient related to the free surface slope, and conversely in the deeper region of the Gulf;2) In the eastern part of the Gulf, the cyclonic gyre intensifies, as observed and reported in the literature;3) For northwesterly winds, the plume from Shatt-al-Arab first heads towards the Iranian coast and then spreads southeastward along the Arabian coast;for northerly and northeasterly winds, the plume directly follows the Kuwaiti coast and then the Arabian coast. This sensitivity of the orientation can be related to the double gyre flow structure;4) A southeasterly wind confines the plume in the northern end of the Gulf as does a pure tidal flow. 展开更多
关键词 PERSIAN GULF wind-induced CIRCULATION Hydrodynamical MODELING
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Case Study of Wind-Induced Vibration of a Cooling Tower Under Typhoon Environment
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作者 XING Yuan ZHAO Lin +1 位作者 CHEN Xu GE Yaojun 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI CSCD 2020年第1期108-119,共12页
As high-rise cooling towers are constantly emerging,wind effects on this kind of wind-sensitive structures have attracted more and more attention,especially in typhoon prone areas.Terrain Type B turbulent flow fields ... As high-rise cooling towers are constantly emerging,wind effects on this kind of wind-sensitive structures have attracted more and more attention,especially in typhoon prone areas.Terrain Type B turbulent flow fields under the normal wind and typhoon are simulated by active wind tunnel technology,and rigid-pressure-measurement model and aero-elastic-vibration-measurement model of a large cooling tower are built.The stagnation point,peak suction point,separation point and leeward point of the throat position shell are selected to analyze pressure coefficient,probability distribution,peak factor,power spectral density and dynamic amplification factor under normal wind and typhoon.It is clarified that there exists a significant non-Gaussian characteristic under typhoon condition,which also exists in structural response level.Resonance response ratio of the total response is higher during typhoon condition.The maximum value of dynamic amplification coefficient under typhoon field is up to 1.18 times over that under normal wind.The findings of this study are expected to be of interest and practical use to professional and researchers involved in the wind-resistant designs of super-large cooling towers in typhoon prone regions. 展开更多
关键词 cooling towers active wind tunnel non-Gaussian characteristic wind-induced vibration dynamic amplification coefficient
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Wind tunnel study on wind-induced vibration of middle pylon of Taizhou Bridge
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作者 Ma Rujin Zhang Zhen Chen Airong 《Engineering Sciences》 EI 2012年第3期77-80,92,共5页
Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbul... Full aero-elastic model tests are carried out to investigate wind-induced vibration of middle steel pylon of Taizhou Bridge. Model of the pylon under different construction periods is tested in both uniform and turbulent flow field. And the yaw angle of wind changes from transverse to longitudinal. Through full aero-elastic model testing, wind-induced vibration is checked, which includes vortex resonance, buffeting and galloping. Vortex resonance is observed and further studies are carried out by changing damping ratio. Based on wind tunnel testing results, wind-resistance of middle pylon is evaluated and some suggestions are given for middle pylon's construction. 展开更多
关键词 wind tunnel test aero-elastic modeL wind-induced vibration middle pylon
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PIV Studies on Turbulence Structure in Air/Water Interface with Wind-Induced Water Waves
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作者 M. Sanjou, I. Nezu A. Toda 《Journal of Energy and Power Engineering》 2011年第11期1063-1067,共5页
When wind appears over the free surface, water waves and turbulence are generated by an interfacial shear stress. In particular, turbulent diffusion promotes significantly mass and momentum transport beneath the inter... When wind appears over the free surface, water waves and turbulence are generated by an interfacial shear stress. In particular, turbulent diffusion promotes significantly mass and momentum transport beneath the interface between the water and air significantly in ocean and lakes, and thus it is very important for global environment problems to reveal such turbulence property and coherent structure. Simultaneous measurements of velocities and free-surface elevation allow us to conduct reasonably the phase analysis of the coherent structure in interfacial shear layer. Furthermore, multi-point measurements such as PIV are very powerful to detect the space-time structure of coherent motions. Therefore, in the present study, we developed a specially designed PIV system which can measure the velocity components and surface-elevation fluctuation simultaneously by using two sets of high-speed cameras to reveal the coherent structure in the interfacial shear layer. 展开更多
关键词 Air/water interface wind-induced water waves PIV measurements.
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改良耳穴压豆联合局部按摩治疗儿童特发性异常瞬目症的临床研究 被引量:1
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作者 郑新宝 张奇佳 +4 位作者 陈春峰 魏嘉洪 陈佳玉 赵永旺 彭清华 《中国中医眼科杂志》 2024年第1期16-21,28,共7页
目的 观察改良耳穴压豆联合局部按摩治疗儿童特发性异常瞬目症的临床疗效。方法 纳入2019年10月—2022年4月在上海市松江区中心医院眼科门诊确诊的4~12岁特发性异常瞬目症患儿90例,随机分成观察组(A组)、中医组(B组)和对照组(C组)各30例... 目的 观察改良耳穴压豆联合局部按摩治疗儿童特发性异常瞬目症的临床疗效。方法 纳入2019年10月—2022年4月在上海市松江区中心医院眼科门诊确诊的4~12岁特发性异常瞬目症患儿90例,随机分成观察组(A组)、中医组(B组)和对照组(C组)各30例(60只眼)。分别予改良耳穴压豆、经典耳穴压豆和常规心理—行为疗法配合滴眼液治疗。3组均观察21 d。分别于治疗前、治疗后测量患儿瞬目频率、学习能力的数据。结果(1)瞬目频率评分:3组治疗前瞬目频率评分比较,差异无统计学意义(P>0.05)。治疗后A组与B组瞬目频率评分均较治疗前降低,差异均有统计学意义(t_(A组)=19.313、t_(B组)=15.000,均P=0.000),C组较治疗前,差异无统计学意义(P>0.05)。治疗后3组间比较,差异有统计学意义(F=1093.886,P=0.000)。与C组比较,A组和B组瞬目频率评分均较低,差异均有统计学意义(t_(A组)=-11.655,t_(B组)=-11.171,均P=0.000);A组和B组比较,差异无统计学意义(P>0.05)。(2)阅读速度比较:治疗后A组与B组阅读速度均较治疗前增加,差异均有统计学意义(t_(A组)=-60.647,t_(B组)=-61.465,均P=0.000),C组较治疗前,差异无统计学意义(P>0.05)。治疗后3组间阅读速度比较,差异有统计学意义(F=19.150,P=0.000)。与C组比较,A组与B组阅读速度均较快,差异均有统计学意义(t_(A组)=4.744、t_(B组)=4.033,均P=0.000);A组与B组比较,差异无统计学意义(P>0.05)。(3)听写速度比较:治疗后A组与B组听写速度均较治疗前增加,差异均有统计学意义(t_(A组)=-115.348、t_(B组)=-109.133,均P=0.000),C组较治疗前,差异无统计学意义(P>0.05)。治疗后3组间比较,差异有统计学意义(F=91.933,P=0.000)。与C组比较,A组与B组听写速度均较快,差异均有统计学意义(t_(A组)=9.751、t_(B组)=8.203,均P=0.000);A组与B组听写速度比较,差异无统计学意义(P>0.05)。(4)中医症候积分:3组治疗前中医症候积分比较,差异无统计学意义(P>0.05)。治疗后A组与B组中医症候积分均较治疗前降低,差异均有统计学意义(t_(A组)=-4.365、t_(B组)=-4.062,均P=0.000),C组较治疗前,差异无统计学意义(P>0.05)。治疗后3组间比较,差异有统计学意义(F=17.259,P=0.000)。与C组比较,A组和B组中医症候积分均较低,差异均有统计学意义(t_(A组)=-4.979、t_(B组)=-4.625,均P=0.000);A组和B组比较,差异无统计学意义(P>0.05)。(5)临床疗效:A组(96.67%)与B组(93.33%)总有效率均优于C组(66.67%),差异均有统计学意义(χ^(2) A组=9.017,P=0.003;χ^(2) B组=6.667,P=0.010),而A组与B组比较,差异无统计学意义(P>0.05)。(6)复发率:A组(10.34%)与B组(14.29%)复发率均低于C组(80.00%),差异均有统计学意义(χ^(2) A组=24.191、χ^(2) B组=20.728,均P=0.000);而A组与B组比较,差异无统计学意义(P>0.05)。结论 改良耳穴压豆联合局部按摩治疗儿童特发性异常瞬目症临床疗效较好,具有操作简单、疗效可靠、复发率低等优势,值得临床推广。 展开更多
关键词 耳穴压豆 局部按摩 儿童 特发性异常瞬目症
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基于改进混合坐标系的大斜视俯冲机动平台SAR快速时域成像算法
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作者 闫莉 许高添 张廷豪 《电子学报》 EI CAS CSCD 北大核心 2024年第10期3472-3481,共10页
多级子图像融合是加速合成孔径雷达(Synthetic Aperture Radar,SAR)时域成像的关键手段.然而,机动平台SAR的大斜视采集增强了频谱支持区域的不规则特性,降低图像融合的效率和精度.针对这些问题,本文设计了一种改进的混合坐标系,在此基... 多级子图像融合是加速合成孔径雷达(Synthetic Aperture Radar,SAR)时域成像的关键手段.然而,机动平台SAR的大斜视采集增强了频谱支持区域的不规则特性,降低图像融合的效率和精度.针对这些问题,本文设计了一种改进的混合坐标系,在此基础上开发了大斜视俯冲机动平台SAR快速时域成像算法.得益于改进混合坐标系中建立的等效斜距模型,频谱对斜视角的敏感度降低,消除了频谱空变现象.因此,设计频谱预处理函数可以有效压缩和拼接频谱,提升图像融合的效率和精度.通过仿真和原始数据处理,验证了提出算法性能的优越性. 展开更多
关键词 快速时域算法 大斜视俯冲机动平台 混合坐标系 等效斜距模型 频谱预处理
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基于椭球模型的斜视星载SAR距离模糊仿真
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作者 蔡佳睿 吕继宇 《雷达科学与技术》 北大核心 2024年第4期434-442,453,共10页
距离模糊比是星载SAR图像的一项重要指标,与正侧视成像相比,大斜视成像星地几何关系更为复杂,传统距离模糊计算与仿真中将地球视为球体的假设会对计算结果造成较大偏差,不能准确评估SAR图像质量。本文采用更为准确的地球椭球模型代替球... 距离模糊比是星载SAR图像的一项重要指标,与正侧视成像相比,大斜视成像星地几何关系更为复杂,传统距离模糊计算与仿真中将地球视为球体的假设会对计算结果造成较大偏差,不能准确评估SAR图像质量。本文采用更为准确的地球椭球模型代替球体模型,并提出了一种基于斜视天线坐标系的模糊区计算方法,利用此方法对距离模糊比沿距离向测绘带的变化进行仿真,同时对距离模糊比沿方位向的空变性也进行研究。本文研究成果对星载SAR系统设计具有重要参考价值。 展开更多
关键词 大斜视星载SAR 距离模糊 椭球模型
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一种适用于星载大斜视聚束SAR的改进距离徙动算法
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作者 邓钱钰 王纪平 +3 位作者 郭淑婷 杨果 刘衍琦 毛新华 《信号处理》 CSCD 北大核心 2024年第3期569-586,共18页
星载大斜视聚束合成孔径雷达(Synthetic Aperture Radar,SAR)探测范围大、目标驻留时间长,有广泛的应用前景,但会带来较大的距离徙动,使得回波信号耦合严重。传统算法使用固定窗接收数据,为了采集完整,则需要较大的采样窗,但采得数据中... 星载大斜视聚束合成孔径雷达(Synthetic Aperture Radar,SAR)探测范围大、目标驻留时间长,有广泛的应用前景,但会带来较大的距离徙动,使得回波信号耦合严重。传统算法使用固定窗接收数据,为了采集完整,则需要较大的采样窗,但采得数据中存在大量的无效数据,采样效率很低。为解决时域采样效率低等问题,可使用滑窗接收模式,但该模式一般结合时域算法或极坐标格式算法使用,而在星载SAR大场景成像的情况下,时域算法计算效率低下,极坐标格式算法的聚焦半径较小,因此本文提出了一种改进的距离徙动算法来解决大斜视滑窗接收模式下的高效精确成像问题。本文建立了滑窗接收模式下的时域回波模型,利用傅里叶变换的性质推导出精确两维解析频谱,并基于上述两维解析频谱,提出雷达视线坐标系下的两维空间域解耦方法并给出对应的完整成像处理流程,最后通过仿真实验验证算法的有效性。本文提出的新方法既能解决大斜视两维频谱扭曲带来的频域采样效率低下问题,又可避免传统方法在大斜视模式下的残留距离徙动放大问题,为后续的自聚焦处理提供便利。 展开更多
关键词 大斜视 星载合成孔径雷达 距离徙动算法 滑窗接收
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