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Modelling of multi-bodies in close proximity under water waves——Fluid resonance in narrow gaps

Science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 16-25页

作者： LU Lin1,2,TENG Bin3,CHENG Liang 4,SUN Liang5 & CHEN XiaoBo6 1 Center for Deepwater engineering,Dalian university of Technology,Dalian 116024,China 2 State Key Laboratory of Structural Analysis for Industrial Equipment,Dalian university of Technology,Dalian 116024,China 3 State Key Laboratory of Coastal and offshore engineering,Dalian university of Technology,Dalian 116024,China 4 School of civil and Resource engineering,The university of Western Australia,Crawly 6003,Australia 5 centre for offshore research and engineering,department of civil engineering,national university of singapore,117576,singapore 6 research department,Bureau Veritas,Neuilly-Sur-Seine,92570,France 1. Center for Deepwater engineering Dalian University of Technology Dalian 116024 China2. State Key Laboratory of Structural Analysis for Industrial Equipment Dalian University of Technology Dalian 116024 China3. State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116024 China4. School of Civil and Resource Engineering The University of Western Australia Crawly 6003 Australia5. Centre for Offshore Research and Engineering Department of Civil Engineering National University of Singapore Singapore 117576 Singapore6. Research Department Bureau Veritas Neuilly-Sur-Seine 92570 France

Viscous fluid model and potential flow model with and without artificial damping force(f=-μV,μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water *** numerical results are compared with experimental data available in the *** comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the resonant frequency reasonably *** the conventional potential flow model(without artificial damping term) significantly over-predicts the wave height in narrow gaps around the resonant *** order to calibrate the appropriate damping coefficient used for the potential model and make it work as well as the viscous fluid model in predicting the resonant wave height in narrow gaps but with little computational efforts,the dependence of damping coefficient μ on the body geometric dimensions is examined considering the parameters of gap width Bg,body draft D,body breadth ratio Br and body number n(n = 2,3),where Br = BB/BA for the case of two bodies(Body A and Body B) with different breadths of BA and BB,*** was confirmed that the damping coefficient used for the potential flow model is not sensitive to the geometric dimensions and spatial *** was found that μ∈ [0.4,0.5] may guarantee the variation of Hg/H0 with kh to be generally in good agreement with the experimental data and the results of viscous fluid model,where Hg is the excited wave height in narrow gaps under various dimensionless incident wave frequencies kh,H0 is the incident wave height,k = 2π/L is the wave number and h is the water depth.

关键词： narrow gap fluid resonance water wave viscous fluid model potential flow model finite element method boundary element method

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Scour and Scour Countermeasures at Bridge Sites

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Transactions of Tianjin university 2008年第4期14卷 289-295页

作者： CHIEW Yee-Meng School of civil and Environmental engineering Nanyang Technological University

This paper examines scour and scour countermeasures at bridge piers and abutments. Abutment scour is by far more complex than its counterpart associated with piers because of the possibility of the presence of a floodplain. Notwithstanding this, the mechanism of scour at both piers and abutments is very similar; moreover, the failure mechanisms associated with both armoring and flow-altering countermeasures are not very different. In rivers with a floodplain, abutment scour becomes much more complex. In cases where the abutment ends at or near to the floodplain, it can initiate bank erosion, which clearly is an important erosion problem that is quite distinct from the customary scour at either an abutment in rivers without a floodplain or a pier. For this reason, abutment scour can be very site-specific while pier-scour is more generic in nature. To this end, the ability to identify the type of abutment scour that may form in a particular channel is closely related to an engineer's ability to propose devices for effective scour *** summarizing research efforts on using riprap as a pier or abutment countermeasure over the past few decades, this paper highlights the deficiencies of riprap in arresting pier scour. To this end, different failure mechanisms are identified. They are shear failure, winnowing failure, edge failure, bedform-induced failure and bed-degradation induced failure. Each failure mechanism can singly or, more likely, combine to cause the eventual breakdown of the riprap layer. The study shows that a riprap layer is vulnerable to other failure mechanisms even though it is adequately designed against shear failure, rendering it ineffective in arresting scour.

关键词： abutment scour pier scour river engineering scour countermeasure riprap protection sediment transport

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Revisited Vanoni-Brooks sidewall correction

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International Journal of Sediment research 2011年第4期26卷 524-528页

作者： Nian-Sheng CHENG 1 Assoc.Prof,School of civil and Environmental engineering,Nanyang Technological university,Nanyang Avenue,singapore 639798. Assoc. Prof. School of Civil and Environmental Engineering Nanyang Technological University Nanyang Avenue Singapore 639798

The evaluation of the sidewall friction could be inconvenient in the implement of the Vanoni-Brooks sidewall correction *** the Colebrook-White equation and Nikuradse’s pipe friction data,two explicit formulae are developed in this note for finding the sidewall friction *** are applicable for various sidewalls that are either hydrodynamically-smooth or rough,or in the transitional regime.

关键词： Sidewall correction Friction factor Open channel flow Pipe flow Sediment transport

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FLOCCULATION/COAGULATION OF NATURAL ORGANIC MATTER FOR PRETREATMENT OF WATER ANDWASTE WATER

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化工学报 2000年第S1期51卷 47-52页

作者： Yu Jiang, Sun Darren Delain and Tay Joo Hwa (Environmental engineering research Center, Division of Environmental & Water Resources engineering School of civil & Structural engineering, Nanyang Technological university 50 Nanyang Avenue, singapore

Characterization of water, waste water and natural organic matter are involved in this paper, and as well as the features of flocculation and coagulation for removing natural organic matter from water and waste water Novel flocculant and coagualant is strongly asked for improving removal efficiency and environment friendly. Enhanced coagulation is introduced to meet the experimental and practical requirement.

关键词： flocculation coagulation natural organic matted enhanced coagulation

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AN ANALYSIS OF THE OXYGEN BALANCE IN AN ANOXIC TIDAL RIVER

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Journal of Hydrodynamics 1994年第4期6卷 83-92页

作者： Joseph H. W. Lee, K. W. Choi (department of civil and Structural engineering, university of Hong Kong)Chen Hui-guo Lin Ming-he(Environmental Sciences research centre, Zhongshan university, Guangzhou 510275, P. R. China) department of civil and Structural engineering University of Hong Kong Hong Kong Environmental Sciences research centre Zhong.shan University Guangzhou 510275 China

A time-dependent, mixed-segment, slack tide oxygen balance model has been developed for the study of a heavily polluted tidal river discharging to a coastal *** and reaeration, BOD settling, benthal demand, freshwater flushing, and tidal mixing are the key processes modelled. Significant features of the model include the oxygen balance formulation under anoxic conditions and the tidal exchange condition at the seaward boundary. The simple model enables a clear and consistent interpretation of a set of dry season water quality data and an assessment of the assimilative capacity of the river is also made.

关键词： tidal river coastal bay water quality oxygen balance.

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Experimental Study of Sediment Incipience Under Complex Flows

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Transactions of Tianjin university 2008年第4期14卷 300-306页

作者： LIU Chunrong DENG Liying HUANG Zhenhua HUHE Aode Maritime research Center School of Civil and Environmental Engineering Nanyang Technological University Singapore 639798 College of Mechanics and Aerospace Hunan University Changsha 410082 China School of civil and Environmental engineering Nanyang Technological University Singapore 639798 Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.

关键词： sediment transport local scour complex flows particle image velocimetry sediment incipience

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地铁诱发的环境振动及振源减振效应的实测与分析

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振动．测试与诊断 2015年第2期35卷 352-358,403页

作者：盛涛张善莉单伽钲施卫星宁波大学建筑工程与环境学院宁波315211 同济大学结构工程与防灾研究所上海200092 Faculty of engineering National University of Singaporesingapore119077

以上海市某地铁线路邻近的六层砌体结构居民建筑为例,通过现场实测,分析了地铁诱发的三向环境振动对室内舒适度的影响程度及主要影响因素;分别在更换了高弹性扣件和降低了列车行驶速度之后,再次对三个正交方向的室内舒适度进行了实测。... 详细信息

以上海市某地铁线路邻近的六层砌体结构居民建筑为例,通过现场实测,分析了地铁诱发的三向环境振动对室内舒适度的影响程度及主要影响因素;分别在更换了高弹性扣件和降低了列车行驶速度之后,再次对三个正交方向的室内舒适度进行了实测。结果表明:a.地铁环境振动主要引起室内楼板的竖向振动,其振级与楼板竖向自振频率直接相关,且沿楼层往上逐层减小,顶层楼面相对于首层可减小约5dB;b.楼板的水平向振动主要受整体结构高阶振型的影响,在某些特定楼层可能出现舒适度超标;c.更换高弹性扣件能明显减小室内楼板的竖向振级,在峰值处可减小约10dB,但也明显放大了其纵向振级,对横向振动的控制效果不明显;d.降低列车行驶速度对三个正交方向的室内舒适度均具有明显的提升效果,竖向振级在峰值处减小约8dB,横向和纵向振级最大减小约30dB,可用于某些环境振动敏感区域进行振动控制。

关键词：地铁环境振动舒适度振源减振现场实测

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Dynamic feedback robust stabilization of nonholonomic mobile robots based on visual servoing

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控制理论与应用（英文版） 2010年第2期8卷 139-144页

作者： Chaoli WANG 1 , Zhenying LIANG 2 , 3 , Qingwei JIA 4 (1.department of Control Science and engineering, university of Shanghai for Science and Technology, Shanghai 200093, China 2.Business School, university of Shanghai for Science and Technology, Shanghai 200093, China 3.School of Science, Shandong university of Technology, Zibo Shandong 255049, China 4.research & Development centre, Hitachi Asia Ltd, Hitachi Tower, singapore 049318) department of Control Science and engineering University of Shanghai for Science and Technology Shanghai China Business School University of Shanghai for Science and Technology Shanghai China School of Science Shandong University of Technology Zibo Shandong China research & Development centre Hitachi Asia Ltd Hitachi Tower Singapore

This paper investigates the visual servoing robust stabilization of nonholonomic mobile robots. The calibration of visual parameters is not only complicated, but also needs great consumption of calculated time so that the accurate calibration is impossible in some situations for high requirement of real timing. Hence, it is interesting and important to consider the design of stabilizing controllers for nonholonomic kinematic systems with uncalibrated visual parameters. A novel uncertain model of these nonholonomic kinematic systems is proposed. Based on this model, a stabilizing controller is discussed by using dynamic feedback and two-step techniques. The proposed robust controller makes the mobile robot image pose and the orientation converge to the desired configuration despite the lack of depth information and the lack of precise visual parameters. The stability of the closed loop system is rigorously proved. The simulation is given to show the effectiveness of the presented controllers.

关键词： Nonholonomic system Uncalibrated visual parameters Stabilization Dynamic feedback

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路面管理理论与方法的研究进展及趋势

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土木工程学报 2004年第1期37卷 65-69,73页

作者：熊辉史其信潘先榜清华大学土木工程系新加坡国立大学交通研究中心

路面是交通基础设施的主要组成部分,路面管理是公路资产管理的重要内容。论文全面回顾了国际国内近年来路面管理领域的最新研究进展,主要包括路面管理过程中路面状况评价、路面性能预测,以及管理策略优化的常用方法、指标及模型,对比分... 详细信息

路面是交通基础设施的主要组成部分,路面管理是公路资产管理的重要内容。论文全面回顾了国际国内近年来路面管理领域的最新研究进展,主要包括路面管理过程中路面状况评价、路面性能预测,以及管理策略优化的常用方法、指标及模型,对比分析了人工神经网络、模糊逻辑和遗传算法等人工智能技术在路面管理中的应用;并对路面管理的发展趋势——公路资产管理这一热点问题进行了探讨。

关键词：路面管理路面状况评价路面性能预测优化公路资产管理

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Blast Protection Shelter by Using Hollow Steel Filled with Recycled Concrete

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Transactions of Tianjin university 2008年第6期14卷 426-429页

作者： LI Jianchun, HUANG Xin HUANG Xin MA Guowe School of civil and Environmental engineering Nanyang Technological University Singapore 639798

Under extreme loading condition,a shelter will provide a safe place to protect people from injury caused by blast wave and *** order to save resource and reuse waste materi-als,a new design concept for blast protection shelter was *** new construction was composed of I-section steel panel or C-channel steel panel filled with recycled concrete *** compaction process of the recycled concrete aggregate filled in the steel construction was ex-perimentally investigated.A single storey shelter based on the proposed design concept was nu-merically simulated by using LS-DYNA *** the 3D numerical model,three walls were de-signed using I-section steel and one wall using C-channel steel,and all of the four walls were filled with recycled concrete *** penetration analysis was done by using *** penetration tests were also carried out by using a gas *** is found that the proposed shelter based on the design concept is effective for blast protection.

关键词： hollow steel panel recycled concrete aggregate shelter LS-DYNA simulation

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