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NUMERICAL STUDY ON THE THREE-DIMENSIONAL CHARA-CTERISTICS OF THE TIDAL CURRENT AROUND HARBOR ENTRANCE

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Journal of Hydrodynamics 2010年第6期22卷 847-855页

作者： xie ming-xiao ZHANG Wei Key Laboratory of Engineering Sediment of Ministry of Transport Tianjin Research Institute for Water TransportEngineering M.O.T. Tianjin 300456 China College of Harbor Coastal and Offshore Engineering Hohai University Nanjing 210098 China

A three-dimensional （3-D） numerical model is established to investigate the tidal current motion characteristics around the harbor entrance. Computational approaches consist of the finite difference method, time-splitting technique, C-grid, and a high-order turbulence closure model. The Ocean General Circulation Model （OGCM） inundation scheme is incorporated in the model. An engineering application, Lianyungang Harbor, China, is used as a real-life case. The model is validated by showing that the simulated results agree well with the field data. In the approach channel, the tidal current shows a deflection effect especially in the bottom layer. As for Lianyungang Harbor, a jet flow forms at the tip of the northern breakwater, which drives a circulation flow at the inner side of the harbor entrance. In the vertical, the flow is significantly stratified at the entrance section within the channel, where the flow direction varies between layers and the speed distribution is quite uniform. These 3-D features become less evident to the offshore. Additionally, the sensitivity analysis shows that the flow deflection is related to the channel depth. Simulation results also imply that the siltation rate at the entrance section of the approach channel tends to be more uniform by the 3-D flow motion feature, and could be more significant with the increase of the channel depth.

关键词： 3-D model harbor entrance OGCM inundation scheme stratification features

Investigation and Discussion on the Beach Morphodynamic Response Under Storm Events Based on A Three-Dimensional Numerical Model

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China Ocean Engineering 2021年第1期35卷 12-25页

作者： xie ming-xiao LI Shan ZHANG Chi YANG Zhi-wen HOU Zhi-qiang ZHANG Huaqing Key Laboratory of Engineering Sediment Tianjin Research Institute for Water Transport EngineeringM.O.T.Tianjin 300456China CCCC First Harbor Engineering Co.Ltd. Tianjin 300461China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China

A well-established 3D phase-averaged beach morphodynamic model was applied to investigate the morphodynamics of a typical artificial beach,and a series of discussions were made on the surfzone hydro-sedimentological processes under calm and storm *** results revealed that the nearshore wave-induced current presents a significant 3D structure under stormy waves,where the undertow and longshore currents exist simultaneously,forming a spirallike circulation system in the *** longshore sediment transport would shorten the sediment supply in the cross-shore direction,subsequently suppress the formation of sandbars,showing that a typical recovery profile under calm waves does not necessarily develop,but with a competing process of onshore drift,undertow and longshore *** transport rate during storms reaches several hundreds of times as those under calm waves,and two storm events contribute approximately 60%to the beach *** transport pattern under calm waves is mainly bed load,but as the fine sands underneath begin to expose,the contribution of suspended load becomes significant.

关键词： beach evolution phase-averaged model wave-induced current storm surge morphodynamics

Nonlinear Absorption-Gain Response and Population Dynamics in a Laser-Driven Four-Level Dense Atomic System

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Communications in Theoretical Physics 2006年第6期45卷 1102-1106页

作者： LI Jia-Hua LIU Ji-Bing LUO Jin-ming xie xiao-Tao Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

We theoretically investigate the response of nonlinear absorption and population dynamics in optically dense media of four-level atoms driven by a single-mode probe laser, via taking the density-dependent near dipoledipole （NDD） interactions into consideration. The influence of the NDD effects on the absorption of the probe field and population dynamics is predicted via numerical calculations. It is shown that the NDD effects can reduce gradually to transient absorption with the increase of the strengths of the NDD interactions, and transient amplification can be achieved. In the steady-state limit, the probe field exhibits transparency for strong NDD interactions. Alternatively, the population entirely remains at the ground state due to the NDD effects.

关键词： absorption spectra population dynamics near dipole-dipole interactions

Study on Hydrodynamic Characteristics of Wave Turbulent Bottom Boundary Layer Using A Large-Sized Wave Flume

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China Ocean Engineering 2021年第5期35卷 759-766页

作者： ZHANG Hong-qian xie ming-xiao ZHANG Chi LI Shao-wu ZHANG Hua-qing SUN Yu-chen State Key Laboratory of Hydraulic Engineering Simulation and Safety Tianjin UniversityTianjin 300072China Tianjin Research Institute for Water Transport Engineering M.O.T..Tianjin 300456China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing 210098China

Experimental studies were conducted in a super-large wave flume,aiming at uncovering the hydrodynamic characteristics involved in the turbulent wave boundary layer of full scale *** explicit formula of boundary layer thickness on rough turbulent flow was presented based on the measured velocity data of the present study and collected experimental data on wave boundary *** was found that the bottom wave-associated nominal stresses under the conditions of prototype scale tests suppress the vertical turbulence scattering upward over the boundary layer,which accounts for thickening of the boundary layer under wave *** effect has yet not been reported in the literatures using oscillatory U-tube or small-sized wave *** phase inconsistency in the turbulent boundary layer to the free stream velocity(velocity immediately outside the boundary layer)is within15°,which is remarkably smaller than the results from oscillatory U-tubes,as well as the larger wave flume experiment presented by xie et al.(2021),showing that the coarser bed would further reduce the phase *** intensity of the vertical turbulent component is approximately 1/2 of the horizontal component,which has larger ratio compared with the value of 1/5 reported by previous ***,it was also found that the vertical turbulent energy was approximately 3/4 of the turbulent energy in spanwise directions(y-direction).This means that the turbulent fluctuation has similar order in all three-directions(x,y,z)in a full scale environment and highlights that the turbulent components in all the three directions should not be neglected when calculating the total turbulent energy.

关键词： large wave flume wave boundary layer hydrodynamic mechanism turbulent

Numerical Modeling of the Undertow Structure and Sandbar Migration in the Surfzone

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China Ocean Engineering 2017年第5期31卷 549-558页

作者： xie ming-xiao ZHANG Chi YANG Zhi-wen LI Shan LI Xin GUO Wei-jun ZUO Shu-hua Key Laboratory of Engineering Sediment Tianjin Research Institute for Water Transport EngineeringM.O.T. National Engineering Laboratory for Port Hydraulic Construction Technology Tianjin Research Institute for Water Transport EngineeringM.O.T. State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Nanjing Hydraulic Research Institute State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Key Laboratory of Coastal Engineering Hydrodynamics of CCCC Tianjin Port Engineering InstituteCCCC College of Environmental Sciences and Engineering Dalian Maritime University

A process-based 3D numerical model for surfzone hydrodynamics and beach evolution was established. Comparisons between the experimental data and model results proved that the model could effectively describe the hydrodynamics, sediment transport feature and sandbar migration process in the surfzone with satisfactory precision. A series of numerical simulations on the wave breaking and shoaling up to a barred beach were carried out based on the model system. Analyzed from the model results, the wave-induced current system in the surfzone consists of two major processes, which are the phase-averaged undertow caused by wave breaking and the net drift caused by both of the nonlinear wave motion and surface roller effect. When storm waves come to the barred beach, the strong offshore undertow along the beach suppresses the onshore net drift, making the initial sandbar migrate to the seaside. Under the condition of calm wave environment, both the undertow and net drift flow to the shoreline at the offshore side of the sandbar, and then push the initial sandbar to the shoreline. The consideration of surface roller has significant impact on the modeling results of the sandbar migration. As the roller transfer rate increases, the sandbar moves onshore especially under the storm wave condition.

关键词： process-based numerical model undertow net driit sediment wansport sandbar migration

A Room-Temperature Pre-calibration Procedure for Gradiometer Sifting

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Chinese Physics Letters 2011年第3期28卷 221-223页

作者： ZHANG Shu-Lin LIU Yang-Bo LIU ming WANG Yong-Liang KONG Xiang-Yan xie xiao-ming State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of SciencesShanghai 200050 Graduate University of the Chinese Academy of Sciences Beijing 1001903 Department of Electronic Science and Technology University of Science and Technology of ChinaHefei 230026

In order to detect extremely weak magnetic signals,superconducting quantum interference device(SQUID)gradiometers are widely used to suppress environmental noise.A hardware SQUID gradiometer consists of a niobium gradio-antenna and an SQUID,which are coupled via an input *** gradiometer imbalance may greatly reduce its noise suppression *** gradiometer balance depends on the geometrical forms of the antenna wound by niobium *** describe a simple method based on Faraday's law for the pre-calibration of the gradiometer balance at room temperature,before the gradiometer is set *** pre-calibrating results are compared with the measured balance of an SQUID gradiometer *** method may be used for sifting hardware gradiometers for multi-channel systems.

关键词： SQUID hardware antenna

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近岸波生流运动三维数值模拟及验证

水科学进展 2011年第3期22卷 391-399页

作者：解鸣晓张玮交通运输部天津水运工程科学研究所工程泥沙交通行业重点实验室天津300456 天津大学建筑工程学院天津300072 河海大学港口海岸与近海工程学院江苏南京210098

开发建立了近岸波生流运动三维数值计算模式。模式中,引入了三维时均剩余动量、破波表面水滚、波浪水平与垂向紊动作为主要驱动力,同时考虑了波流共同作用的底部剪切力。推导了可综合反映底坡、能量传递率和密度影响的水滚能量传输方程;... 详细信息

开发建立了近岸波生流运动三维数值计算模式。模式中,引入了三维时均剩余动量、破波表面水滚、波浪水平与垂向紊动作为主要驱动力,同时考虑了波流共同作用的底部剪切力。推导了可综合反映底坡、能量传递率和密度影响的水滚能量传输方程;将Larson-Kraus的二维波浪水平紊动系数表达式拓展至三维。采用大量实测数据和文献资料测试验证了所建模式,表明所建模式可有效模拟波浪增减水、底部离岸流、沿岸流、裂流、堤后环流等不同维度的波生流现象。此外,研究也表明破波水滚效应可解释波生流峰值向岸推移的物理现象,从而在模拟中不能忽略;破波带内沿岸流速垂向较为均匀的现象与波浪附加垂向紊动有关。

关键词：三维波生流时均剩余动量破波水滚波浪紊动模式验证

A SQUID Bootstrap Circuit with a Large Parameter Tolerance

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Chinese Physics Letters 2013年第1期30卷 219-222页

作者： ZHANG Guo-Feng ZHANG Yi Hans-Joachim Krause KONG Xiang-Yan Andreas Offenhäusser xie xiao-ming State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyChinese Academy of Sciences(CAS)Shanghai 200050 Peter Grünberg Institute(PGI-8) Forschungszentrum Jülich(FZJ)D-52425JülichGermany Joint Research Laboratory on Superconductivity and Bioelectronics Collaboration between CAS-Shanghai&FZJShanghai 200050

The voltage biased(SQUID)bootstrap circuit(SBC)was recently introduced as an effective means to reduce the preamplifier noise *** analyze the tolerances of the SBC noise suppression performance to spreads in SQUID and SBC circuit *** is found that the tolerance to spread mainly caused by the integrated circuit fabrication process could be extended by a one-time adjustable current feedback.A helium-cooled niobium SQUID with a loop inductance of 350 pH is employed to experimentally verify the *** this work,design criteria for fully integrated SBC devices with a high yield can be derived.

关键词： SQUID Bootstrap spread

Time-Domain Frequency Correction Method for Averaging Low-Field NMR Signals Acquired in Urban Laboratory Environment

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Chinese Physics Letters 2012年第10期29卷 213-216页

作者： QIU Long-Qing LIU Chao DONG Hui XU Lu ZHANG Yi Hans-Joachim Krause xie xiao-ming Andreas Offenhäusser State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information TechnologyShanghai 200050 Peter Grünberg Institute(PGI-8) Forschungszentrum JülichJülichD-52425Germany Joint Research Laboratory on Superconductivity and Bioelectronics Collaboration between CAS-Shanghai and Forschungszentrum JülichShanghai 200050 Graduate University of the Chinese Academy of Sciences Beijing 100049

Using a second-order helium-cooled superconducting quantum interference device gradiometer as the detector,ultra-low-field nuclear magnetic resonance(ULF-NMR)signals of protons are recorded in an urban environment without magnetic *** homogeneity and stability of the measurement field are *** signals of protons are studied at night and during working *** Larmor frequency variation caused by the fluctuation of the external magnetic field during daytime reaches around 5 Hz when performing multiple measurements for about 10 min,which seriously affects the results of *** order to improve the performance of the averaged data,we suggest the use of a data processor,*** so-called time-domain frequency correction(TFC).For a 50-times averaged signal spectrum,the signal-to-noise ratio is enhanced from 30 to 120 when applying TFC while preserving the NMR spectrum *** TFC is also applied successfully to the measurement data of the hetero-nuclear J-coupling in 2,2,2-trifluoroethanol.

关键词： NMR averaged spectrum