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Tuan, T.Q. (author), Stive, M.J.F. (author), Verhagen, H.J. (author)Under effects of tropical cyclones, the coast is subjected to attack both by surge and wave from the sea and by flooding from the bay. These forces pose a serious breaching threat to natural sea-defence works such as barrier spits, barrier islands, lagoon barriers, etc. on the coast. Unintended breaching can be catastrophic, causing losses of...conference paper 2006
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Lam, T.N. (author), Stive, M.J. (author), Verhagen, H.J. (author), Wang, Z.B. (author)Thuan An is a tidal inlet located in Vietnam in a tropical monsoon area. The inlet is very dynamic and variable under the influences of not only tides and waves from the sea but also flows and floods from upstream rivers. Therefore, morphodynamic behaviour of the inlet is very complicated and not well understood. Studies on inlet are also facing...conference paper 2006
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Hamelinck, R. (author), Rosielle, N. (author), Steinbuch, M. (author), Ellenbroek, R. (author), Verhagen, M. (author), Doelman, N. (author)In the design of a large adaptive deformable membrane mirror, variable reluctance actuators are used. These consist of a closed magnetic circuit in which a strong permanent magnet provides a static magnetic force on a ferromagnetic core which is suspended in a membrane. By applying a current through the coil which is situated around the magnet,...conference paper 2006
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Tuan, T.Q. (author), Verhagen, H.J. (author), Visser, P.J. (author), Stive, M.J.F. (author)To increase physical insight into wave overwash processes at low-crested beach barriers, wave overtopping discharge events rather than the conventional average overtopping discharge need to be quantified. Also, in order to make intelligent use of the many empirical formulations on wave overtopping discharge at breakwaters from literature, a...journal article 2006
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Verhagen, H.J. (author), Reedijk, B. (author), Muttray, M. (author)Experience has shown that stability parameters for breakwater armour are different for steep and shallow foreshores, as well as for deep and shallow water. A change from a deep water spectral information (Tm0) to shallow water spectral information (Tm-1,0) does not completely explains this difference. Tests have shown that stability also depends...conference paper 2006
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Van Oosten, R.P. (author), Peixó Marco, J. (author), Van der Meer, J.W. (author), Van Gent, M. (author), Verhagen, H.J. (author)The European Union funded project DELOS was focused on wave transmission and an extensive database on low-crested rubble mound structures was generated. During DELOS, new empirical wave transmission formulae were derived. These formulae still showed a considerable scatter due to a limited number of parameters included. Neural networks based on a...conference paper 2006
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Tuan, T.Q. (author), Verhagen, H.J. (author), Visser, P.J. (author)A hydrodynamic numerical model is formulated to describe the breach erosion process of sandy barriers. The breach flow is based on the system of unsteady shallow water equations, which is solved using a robust upwind numerical approach in conjunction with the Finite Volume Method (FVM). The hydraulic jump is considered as part of the breach flow...conference paper 2006
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Tuan, T.Q. (author), Verhagen, H.J. (author), Visser, P.J. (author), Stive, M. (author)For management of coastal breaching hazards it is critical to be able to assess the potential of coastal barrier breaching as a result of wave actions during storm surges (wave overwash). This phenomenon is known as the breach initiation phase; the mechanisms behind this are not very well understood. In the present study, laboratory experiments...conference paper 2006
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Terrile, E. (author), Reniers, A.J.H.M. (author), Stive, M.J.F. (author), Tromp, M. (author), Verhagen, H.J. (author)Incipient motion of coarse particles under regular shoaling waves is examined. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created....journal article 2005
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Verhagen, H.J. (author)In case of coasts with steep foreshores coastal structures suffer more from damage than normally could be expected from given boundary conditions at deep water. For that reason in many guidelines it is recommended to apply a heavier class of rock in those cases; manufacturers of single layer units (like Accropode, Core-loc or Xbloc) recommend a...conference paper 2005
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Verhagen, S. (author)The principle of positioning with the Global Positioning System (GPS) is based on determining the distance of at least four GPS satellites to a receiver. For that purpose the so-called code measurements can be used, so that the position of the receiver can be determined up to several meters. In order to allow for navigation with centimeter...doctoral thesis 2005
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Stive, M.J.F. (author), Terrile, E. (author), Reniers, A.J.H.M. (author), Verhagen, H.J. (author)Threshold of motion of coarse particles under regular shoaling waves is studied. Experiments were performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were created...conference paper 2005
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Stive, M.J.F. (author), Reniers, A.J.H.M. (author), Terrile, E. (author), Verhagen, H.J. (author)The threshold of motion of coarse particles under regular shoaling waves is studied. Experiments are performed to investigate the effects of bed fluid acceleration on coarse particle stability. By varying wave height, wave period and water depth, combinations of similar peak orbital velocities and weak to strong intra-wave accelerations were...conference paper 2005
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Verhagen, H.J. (author)In 1991 CUR in the Netherlands and CIRIA in the UK have published the "manual on the use of rock in coastal engineering", usually referred to as the "Rock Manual". This book of 600 pages gave an overview of the state of the art regarding the design of rock structures along coasts. In 1995 CUR published a adapted version of this book, also...conference paper 2005
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Verhagen, H.J. (author)Coastal engineering is a complex art. At this moment a limited number of phenomena can understood with the help of the laws of physics and fluid mechanics. For the remainder, formulas have been developed with limited accuracy. In addition, input data are also limited available, and form another source of uncertainty. Consequently, a sound...conference paper 2005
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Verhagen, H.J. (author)This paper gives an overview of some recent developments in structures for coastal protection. Single layer units like Accropode and Xbloc are rather popular at this moment; research indicates that also cubes can be placed in single layers. Also the use of heavy aggregates in concrete can be beneficial for the stability and economics. Structures...conference paper 2004
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)This paper presents an application of an one-dimensional unsteady numerical model DUFLOW for hydrodynamic simulation of a complex lagoon-inlet system in Vietnam. The difficulties due to the lack of data for model boundary conditions is overcome by using sensitivity analysis approach for the uncertainties of boundary conditions. Model results are...journal article 2004
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Lam, N.T. (author), Verhagen, H.J. (author), Van der Wegen, M. (author)Stability analysis of tidal inlets is very important in providing knowledge on the behaviour of tidal inlet and lagoon systems. The analysis results can help to plan and manage the system effectively as well as to provide information for stability design of the inlets. This paper presents a method of building and applying the Escoffier diagram...journal article 2004
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De Jong, W. (author), Verhagen, H.J. (author), Olthof, J. (author)Physical model tests were done on an armour of Tetrapods, placed in a single layer. The objective of the investigations was to study the stability of the secondary layer, and to see if the material of this secondary layer could be washed out through the single layer of Tetrapods. It was concluded that secondary armour is not washed out through...conference paper 2004
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Verhagen, H.J. (author), Steenaard, J. (author), Tuan, T.Q. (author)A number of equations has been developed for calculation overtopping quantities over breakwaters, as well as equations to describe the stability of the inner slope. However, not all the water which overtops the outer boundary of the breakwater will reach the inner slope; part of the water is infiltrated in the crest. In this paper data are...conference paper 2004