286 research outputs found
Stability of rock on slopes under wave attack: Comparison and analysis of datasets Van der Meer [1988] and Van Gent [2003]
No full textIn VAN GENT [2004] graphs were presented in which the datasets of VAN DER MEER [1988] and VAN GENT ET AL. [2003] were compared, but in this comparison a number of parameters were not correctly transformed into a comparable format. In this M.Sc. thesis after an extensive analysis to the datasets all parameters of the datasets of Van der Meer were transformed into the same format as the parameters used by Van Gent. In the same way the dataset of THOMPSON & SHUTTLER [1975], which formed the basis of the work of Van der Meer, was treated. The inclusion of correction factors for the effects of stone roundness from LATHAM ET AL. [1988] gave remarkable effects on a certain part of the dataset of Van der Meer which showed more damage than average. After this still differences could be seen between the datasets of Van der Meer and Van Gent. Using the statistical T-test these differences are approved. Explanations for the differences found between the datasets of Van der Meer and Van Gent can be found in the fact that most of the tests of Van Gent. were done with shallow foreshores where Van der Meer did most tests with deep water conditions. Tests by a number of M.Sc. students at Delft University of Technology showed that tests with identical spectra, but with different foreshore slope angles show different damage patterns. In the dataset of Van Gent also the 1:30 foreshore slopes on average show more damage than the 1:100 slopes. In further research the influence of the foreshore should be incorporated in the stability formulae by a foreshore Iribarren parameter. Also a detailed investigation to the effects of wave breaking on shallow foreshores is needed. For this the complete dataset of Van Gent needs to be available and accessible.Hydraulic EngineeringCivil Engineering and Geoscience
Gezocht en gevonden, bodemvondsten uit Gent /
No full textNadat archeologisch onderzoek aan de Waalse Krook in Gent was afgerond, doorzochten vier detectoramateurs bijna een jaar lang de niet-doorzochte grond. Het resultaat was verbluffend. In dit boek onthullen Denny Bogaert, Michel Krijgsman, Paul Callewaert en Marcel de Putter hun (laat)middeleeuwse bodemvondsten. Daarbij wordt uitgebreid verteld over de geschiedenis van Gent, de Waalse Krook, de markante bewoners en natuurlijk al die unieke teruggevonden voorwerpen: insignes, gereedschappen, sieraden, eet-, drink- en keukengerei, kinderspeelgoed, sleutels, munten, muntgewichten. En méér.Nadat archeologisch onderzoek aan de Waalse Krook in Gent was afgerond, doorzochten vier detectoramateurs bijna een jaar lang de niet-doorzochte grond. Het resultaat was verbluffend. In dit boek onthullen Denny Bogaert, Michel Krijgsman, Paul Callewaert en Marcel de Putter hun (laat)middeleeuwse bodemvondsten. Daarbij wordt uitgebreid verteld over de geschiedenis van Gent, de Waalse Krook, de markante bewoners en natuurlijk al die unieke teruggevonden voorwerpen: insignes, gereedschappen, sieraden, eet-, drink- en keukengerei, kinderspeelgoed, sleutels, munten, muntgewichten. En méér
[photograph] Gent : Nieuw Circus : Portret van Marcel Wittrisch (reproductie).
No full textOnder de foto staat : "M. Marcel Wittrisch, le magnifique interprête de 'Lohengrin', qu'il chantera encore dimanche en matinée."Uitgeknipte (kranten)foto.Bijzondere collectie
Jan Moke. Miniaturist Gent-Brugse school 1478.
No full textHet doel van deze bijdrage is aan te tonen dat Jan Moke omstreeks 1478 te Gent verbleef en behoorde tot de stadsgenoten, zoals de bekende miniaturisten: Sander Bening, Claas Spierinc, Johannes Spierinc, Gheeraert Horenbout.</jats:p
Laboratory investigation on armour stability for extremely shallow water conditions
No full textInternational audienceThe hydraulic stability of the armour layer has been widely discussed in literature, and several formulas have been proposed for design purpose. Nevertheless, few studies focused on the armour behaviour in case of limited water depths. The objective of the present research is to provide more insights on the stability of the armour layer till extremely shallow water conditions. New physical experiments have been carried out in the wave flume at the Environmental European Maritime and Environmental Research Laboratory (EUMER) of the University of Salento (Lecce), in presence of a 1 to 30 foreshore. Tests aimed to investigate both the nearshore hydrodynamics and the hydraulic stability under different irregular wave attacks. Four water depths were adopted and in order to produce a significant damage to the structure, the rock size was scaled down accordingly. After each test, the erosion area (Ae) has been quantified by a laser bed profiling system, and the structure damage (S= Ae÷Dn50²), where Dn50 is the rock nominal diameter, has been determined to investigate it in a range between 0 and 12, useful for design purposes. Moreover, both statistical and spectral wave characteristics, have been retrieved from resistive wave gauges located along the flume and at the structure toe. The latter have been evaluated even without the breakwater, since no reflection analysis is suitable in shallow water conditions (Van Gent, 1999). In the full paper the experimental set-up will be described together with the main preliminary results. Specifically, the measured damage S calculated after each test in different shallowness conditions will be reported and discussed. Experimental results will be also compared to the damage computed by applying the widespread formulas of Van der Meer (1988) and Van Gent et al. (2004), in order to understand if the formulations are able to predict the level of damage when the breaker parameter ξm is larger than 1
Oblique Wave Attack on Rubble Mound Breakwater Crest Walls of Finite Length
No full text[EN] Rubble mound breakwaters usually present a crest wall to increase the crest freeboards without a large increase of the consumption of material. Methods in the literature to design crest walls are based on estimates of the wave loads. These methods are focused on the maximum loading that attacks a single position of the crest wall. In practice, crest walls have a finite length. Since the maximum loading does not occur at the same instant over the entire length of the crest wall for oblique waves, these methods overestimate the loading in the situation of oblique waves. Wave loads under oblique wave attack have been measured in physical model tests. A method to account for the effect of the finite length of crest walls has been developed, and design guidelines have been derived. The results of this study in combination with the existing methods in the literature to estimate the wave forces enable a more advanced design of crest walls.The first author was financially supported by the Ministerio de Educacion, Ciencia y Deporte through the FPU program (Formacion de Profesorado Universitario) under grant FPU16/05081.Mares-Nasarre, P.; Van Gent, MR. (2020). Oblique Wave Attack on Rubble Mound Breakwater Crest Walls of Finite Length. Water. 12(2):1-21. https://doi.org/10.3390/w12020353S121122Molines, J., Herrera, M. P., & Medina, J. R. (2018). Estimations of wave forces on crown walls based on wave overtopping rates. Coastal Engineering, 132, 50-62. doi:10.1016/j.coastaleng.2017.11.004Jacobsen, N. G., van Gent, M. R. A., Capel, A., & Borsboom, M. (2018). Numerical prediction of integrated wave loads on crest walls on top of rubble mound structures. Coastal Engineering, 142, 110-124. doi:10.1016/j.coastaleng.2018.10.004Van Gent, M. R. A., & van der Werf, I. M. (2019). Influence of oblique wave attack on wave overtopping and forces on rubble mound breakwater crest walls. Coastal Engineering, 151, 78-96. doi:10.1016/j.coastaleng.2019.04.001A Monograph of Rubble Mound Breakwatershttps://repository.tudelft.nl/islandora/object/uuid%3A133be463-5f43-45cd-9115-3ef9ebe245b3Martin, F. L., Losada, M. A., & Medina, R. (1999). Wave loads on rubble mound breakwater crown walls. Coastal Engineering, 37(2), 149-174. doi:10.1016/s0378-3839(99)00019-8Nørgaard, J. Q. H., Andersen, T. L., & Burcharth, H. F. (2013). Wave loads on rubble mound breakwater crown walls in deep and shallow water wave conditions. Coastal Engineering, 80, 137-147. doi:10.1016/j.coastaleng.2013.06.003Report H3608. Physical Model Investigations on Coastal Structures with Shallow Foreshores; 2D Model Test with Single and Double-Peaked Wave Energy Spectrahttps://repository.tudelft.nl/islandora/object/uuid:1b4729de-2e86-4b8a-98d5-48d8e07d5902?collection=researchMares-Nasarre, P., Argente, G., Gómez-Martín, M. E., & Medina, J. R. (2019). Overtopping layer thickness and overtopping flow velocity on mound breakwaters. Coastal Engineering, 154, 103561. doi:10.1016/j.coastaleng.2019.103561Herrera, M. P., & Medina, J. R. (2015). Toe berm design for very shallow waters on steep sea bottoms. Coastal Engineering, 103, 67-77. doi:10.1016/j.coastaleng.2015.06.00
On the mean overtopping rate of rubble mound structures
No full textEstimation of the mean overtopping discharge is a major task in the design and assessment of the crest level of rubble mound structures such as breakwaters and seawalls. The tolerable mean overtopping rates are given based on the associated risk and wave characteristics. Several empirical formulas have been developed for the prediction of mean overtopping discharge at coastal structures. These formulas can be applied to a wide variety of coastal structures, but have limited accuracy and/or do not reflect the physics of the phenomena. The main aim of this study is to overcome these issues for rubble mound structures by considering the physics of the process in the formula development. To achieve this, first, the references used in the extended CLASH database (also called the EurOtop-2018 database), were scrutinized, the reported wave characteristics were corrected (if required) and the rubble mound structure subset was extended using a recent study. Then noting that overtopping occurs when the wave runup exceeds the freeboard, the difference between the maximum wave runup and crest freeboard was considered as the governing parameter in the mean overtopping discharge formula. In the developed formula, a semi-empirical relationship between the mean overtopping and wave runup has been established. The performances of the developed formulas and existing ones were evaluated both qualitatively and quantitively. Accuracy metrics such as RMSE and BIAS indicated the superiority of the developed simple formula. Finally, a design formula to consider uncertainty and some guidelines are provided for practitioners.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Coastal Engineerin
Herdenkingstentoonstelling André Beullens, Marcel Broodthaers, Amedeus Cortier Stadt Gent, Museum van Hedendaagse Kunst, Citadelpark, 10 juni - 24 juli 1977
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