2,983 research outputs found
On sustainable delta development: Sustainable coastal adaptation is possible - Water as catalyst for sustainable development
No full textThe main ingredient of Delta Urbanism is the dialogue. The integration of concepts, ideas, language and measures can only be done through conscious exchange in continuous dialogue. This is not taken lightly, just exchange is not good enough, a solid dialogue is conscious and supported by methods that orchestrate steps, information and design.
Therefore a section in which dialogue between two professionals is presented is essential to this journal. The exchange is directed through writing and editing, taking time to think responses through and position clearly in the dialogue.
This issue represents the dialogue between Bas Jonkman and Henk Ovink who continue the dialogue that they started as keynote speakers at the conference of Delta Urbanism in times of climate crisis in March 2020
Hoogwater 2021: Feiten en Duiding
No full textIn juli 2021 zijn grote delen van Limburg getroffen door hevige regenval en overstromingen. Ook delen van België en Duitsland overstroomden met zeer veel schade en verlies aan mensenlevens tot gevolg. Dit betrof een extreme en ongeëvenaarde gebeurtenis met enorme impact. Daarom is naar aanleiding van de overstromingen deze verkenning uitgevoerd om een eerste stap te maken om beschikbare informatie over deze gebeurtenis te verzamelen en analyseren. Het onderzoek is uitgevoerd door een breed consortium (TU Delft, Deltares, HKV Lijn in Water, VU Amsterdam, Universiteit Utrecht, KNMI, WUR, Erasmus MC en Universiteit Twente) in opdracht van het Expertise Netwerk Waterveiligheid (ENW). Een overstroming heeft effect op de hele maatschappij. Daarom zijn niet alleen hydrologische en civieltechnische onderwerpen beschouwd, maar ook de maatschappelijke gevolgen van overstromingen, de crisisrespons en de gezondheidseffecten.Contributors (in alphabetical order): Nathalie Asselman (Deltares), Hermjan Barneveld (HKV / Wageningen UR), Jules Beersma (KNMI), Eline Boelee (Deltares), Wouter Botzen (VU Amsterdam), Eefke Copper (TU Delft), Dim Coumou (KNMI), Karin de Bruijn (Deltares), Anniek de Jong (Deltares), Jurjen de Jong (Deltares), Hans de Moel (VU Amsterdam), Ferdinand Diermanse (Deltares), Astrid Fischer (Evides) , Gert-Jan Geerling (Deltares), Marie-Louise Geurts (WML), Rob Groenland (KNMI), Mark Hegnauer (Deltares), Bas Jonkman (TU Delft), Nicole Jungermann (KNMI), Frans Klijn (Deltares), Andre Koelewijn (Deltares), Matthijs Kok (HKV / TU Delft), Elco Koks (VU Amsterdam), Bas Kolen (HKV / TU Delft), Marion Koopmans (Erasmus MC), Laurens Leunge (Deltares), Hans Middelkoop (Utrecht University), Roelof Moll (TU Delft), Jaap Mos (Dunea), Sjoukje Philip (KNMI), Gerbert Pleijter (HKV), Joost Pol (HKV / TU Delft), Stephan Rikkert (TU Delft), Guus Rongen (TU Delft), Rinus Scheele (KNMI), Julius Schlumberger (TU Delft), Peter Siegmund (KNMI), Kymo Slager (Deltares), Frederiek Sperna Weiland (Deltares), Bart Strijker (HKV / TU Delft), Henk v.d. Brink (KNMI), Janko van Beek (Erasmus MC), Marion van den Bulk (TU Delft), Bart van den Hurk (Deltares), Tim van Emmerik (Wageningen UR), Kees van Ginkel (VU Amsterdam / Deltares), Mick van Haren (TU Delft), Margreet van Marle (Deltares), Malou van Schaijk (TU Delft), Dennis Wagenaar (Nanyang TU), Davide Wüthrich (TU Delft)Hydraulic Structures and Flood RiskSafety and Security ScienceCoastal Engineerin
Bas-Relief Modeling from Normal Layers
No full textBas-relief is characterized by its unique presentation of intrinsic shape properties and/or detailed appearance using materials raised up in different degrees above a background. However, many bas-relief modeling methods could not manipulate scene details well. We propose a simple and effective solution for two kinds of bas-relief modeling (i.e., structure-preserving and detail-preserving), which is different from the prior tone mapping alike methods. Our idea originates from an observation on typical 3D models which are decomposed into a piecewise smooth base layer and a detail layer in normal field. Proper manipulation of the two layers contributes to both structure-preserving and detail-preserving bas-relief modeling. We solve the modeling problem in a discrete geometry processing setup that uses normal-based mesh processing as a theoretical foundation. Specifically, using the two-step mesh smoothing mechanism as a bridge, we transfer the bas-relief modeling problem into a discrete space, and solve it in a least-squares manner. Experiments and comparisons to other methods show that (i) geometry details are better preserved in the scenario with high compression ratios, and (ii) structures are clearly preserved without shape distortion and interference from details.Accepted author manuscriptMaterials and Manufacturin
Building safety with nature: Salt marshes for flood risk reduction
No full textFlood risk reduction in coastal areas is traditionally approached from a conventional engineering perspective, where dikes and dams are built to withstand the forces of tides, surges and waves. Recently, a nature-based approach to flood risk reduction is increasingly promoted, in which the benefits of coastal ecosystems for reducing the impact of extreme weather events are utilized. Ecosystems such as salt marshes, mangrove forests, coral reefs and sand dunes are preserved, enhanced or even created, in order to reduce flood risk in coastal areas. Nature-based flood defenses can work stand-alone, like sand dunes, but can also function in combination with engineered defenses, for example when vegetated foreshores reduce wave loads on dikes or dams.Coastal Engineerin
Stability of rock-based emergency measures based on the Grave Weir calamity
No full textOn the 29th of December 2016 a large Rhine ship loaded with 2000 ton benzene sailed through the weir at Grave, located in the river Meuse in the Netherlands. The accident created a large gap in the weir and within 12 hours the upstream water level decreased by a maximum of 3 meters. Due to this decreased water level shipping was limited, houseboats were skewed and there was a risk of instability of the river banks and upstream weirs.Several alternative measures were considered to close the damaged part of the weir in order to reinstate the upstream water level, and make it possible to repair the weir. Finally it was decided to build a rock-fill dam behind the damaged part of the weir which closed nearly 55% of the weir. Due to this closure, all the discharge had to pass the weir through the remaining 50 meters-wide southern opening. As a result of this upstream water levels were set-up faster than during normal operations. High upstream water levels, relatively high discharges and a low downstream water level caused extreme flow situations with even supercritical flow (hydraulic jump) over the bed protection. At weir Grave the existing bed protection was injected with colloidal concrete and an additional ballasting sill, made of 3-6t carefully placed stones and 4t rock nets was constructed, to prevent additional damage to the bed protection.In this study the stability of the measures which were used to prevent additional damage to the bed protection are analyzed. This study focusses on the 3-6t carefully placed stones, rock net sill and the bed protection behind it. The 4t rock nets were not able to withstand discharges up to 450m3/s and flow velocities up to 7.0m/s due to the internal instability of the small rock material inside the nets. The 3-6t stones were able to withstand discharges up to 850m3/s and flow velocities up to 6.7m/s. Due to the fact that the stones were carefully placed, the stability increased. A stability correction factor (Φsc) up to 0.73 can be used instead of 1.5 as prescribed by Pilarczyk for stones on the edge of a bed protection. The 40-200kg bed protection with colloidal concrete has withstood extreme flow velocities up to 7.2m/s whereby only small damages occurred. The 40-200kg quarry stones without colloidal concrete also showed limited damages after the 850m3/s flood wave and depth averaged flow velocities up to 5.2m/s. The conclusions of the analysis are projected to the other six weirs in the Meuse and to the possible calamities which could occur here.In order to perform the stability analysis of the bed protection measures at weir Grave, the Meuse and the seven weirs in the Meuse were analyzed. The Meuse is a controlled river in the Netherlands and is kept navigable by a seven weir system. These weirs differ in dimension, head loss and operating system. Based on the characteristics of these weirs one simplified fictive weir is chosen and tested on the consequences of various calamities. Besides, also the long-term maintenance strategy is considered in this study. Both have the similar result that part of the weir is non-operational for a longer period, discharge capacity is limited and all highly variability in occurring discharges is possible.In this study the consequences to the water management of the fictive weir are considered. To guarantee an upstream water level to a certain target level, panels and slides are removed from a weir for increasing discharge. If part of the weir is not available due to a closure, panels and slides have to be removed earlier than in a normal situation. Therefore, the limit discharge, the discharge for which the weir is completely open, is reached earlier for the different closure situations. If the limit discharge is reached, the upstream water level starts to increase. In this thesis the discharge, according to an upstream water level equal to the flood plain level, is the maximum considered discharge. For further increasing discharge, and water levels, the flood plains start to discharge water and the flow velocities downstream of the weir will no further increase.The flow velocities for three closure situations and three discharge situations are considered in this study. It turned out that the flow velocities which are calculated in this thesis are always lower than the flow velocities which occurred during the Grave weir calamity. Therefore it is concluded that the measures used during the Grave calamity, are all applicable to the other weirs in the Meuse. But lastly is must be concluded that due to a relative large closure of a weir (>50%), severe flow circumstances like supercritical flow, can occur. In case of a future calamity or long-term closure, it is advised to minimize the closure width as much as possible.Civil Engineerin
Spatial integration of dike reinforcements: Development of a method that compares the spatial influence of design alternatives
No full textIn the Netherlands, a new assessment method for the required safety level of primary flood defences is introduced in the Water Act. It is estimated that currently roughly 1900 kilometres of flood protection does not meet the safety requirements for the future (Jonkman, Jorissen, Schweckendieck & Van den Bos, 2017). Past flood defence projects show that integrating reinforcement measures is a difficult assignment. It is specifically focused on dike reinforcement projects in this thesis. A deficiency in the design process is identified in the role that the influence on the existing situation has on the evaluation and selection of design alternatives that are input for the Environmental Impact Assessment. The difficulty for improving the importance of the existing situation in the surroundings, in the design process is that the subject experts on these themes are typically assessing the consequences of proposed interventions (Aalberts, 2018). The research objective is set to develop a method that allows to include the influence on the existing situation within the evaluation and selection of design alternatives in dike reinforcement projects. This method aims for providing information to compare the spatial integration of reinforcement designs in early stages of reinforcement projects. Subject experts should assess the provided information, and determine whether a reinforcement design provides a satisfying influence on the project area. It is focused on dike reinforcement projects in rural area. A research through design study is used to develop the method to compare design alternatives. The study included the identification of technical design measures to increase the strength of dikes in rural area, and the decomposition of rural areas in functional characteristics that can be valued. A conceptual evaluation model is developed to express the relation between functional characteristics and design alternatives for dike reinforcements. It is studied how a method can be provided to compare the outcome of the conceptual evaluation model for a large variety of design alternatives. The value of the developed method is assessed in a case study, which is the dike reinforcement project “Wolferen-Sprok”. The resulting method is able to compare design alternatives on the influence on the existing situation by following seven steps. It is providing design measures for the identified safety problem of the dike in a certain project area. Simultaneously, the characteristics of the project area should be identified and visualized on maps. This provides the required information to apply the conceptual evaluation model that identifies effects of design alternatives on the existing situation. The retrieved data is visualized to compare design alternatives. It is concluded that the developed method focusses mainly on natural, cultural, and social economic functions in rural project areas. This means that influence of design alternatives on costs, maintainability, and landscape values should be addressed separately, in the evaluation and selection of design alternatives. It is recommended to study how the influence on these topics can evaluated in a similar method. The developed method can be applied to include the existing situation in the project area in the evaluation and selection of design alternatives in dike reinforcement projects in rural areas. It is expected that application of the method in design teams provides new input for further improvement of the method.Civil Engineering | Hydraulic Engineerin
Wave loads on vertical walls: Validation of design methods for non-breaking waves of bimodal spectra
No full textDuring the design process of the new sea lock in IJmuiden the design wave conditions were described by a bimodal wave spectrum. With a spectral calculation method it was observed that a small low frequency component leaded to a large influence in the force spectrum. This observation served as the starting point for this thesis, where different design methods were validated for the non-breaking wave load of bimodal wave spectra on a vertical wall. The design methods under consideration were the formulae of Sainflou, Goda, the linear wave theory and the spectral calculation method. These methods were validated by the phase-resolved numerical model SWASH. First, the characteristic wave force for different shapes of spectra was addressed. In addition, the probability distribution of wave force was compared with the Rayleigh distribution. It turned out that the large influence of a low frequency component in a bimodal wave spectrum may cause underestimations of the traditional design formulae. The spectral calculation method performed accurate for all considered wave conditions.<br/
FM Transceiver for Wireless Communication: Audio and Intermediate Frequency Amplifiers
No full textIn this bachelor thesis the design process of the audio and intermediate frequency amplifiers for a wireless FM tranceiver is documented and explained. The project was done using only descrete components for educational purposes.2019 Ivor Bas, Victor hoedemakerElectrical Engineerin
Bending Vibrations of the Afsluitdijk Gates Subjected to Wave Impacts: A Comparison of two Design Methods
No full textThis paper describes a first case study of the application of a newly developed fluid-structure interaction model to the design of flood gates. The gates in the Afsluitdijk, that will be replaced in the coming years, are considered. Due to the presence of a concrete beam in front of the gates breaking wave can occur, leading to high impact pressures acting on the gate. For this case both a quasi-static approach and a more detailed semi-analytical model representing the dynamic behaviour including fluid-structure interac-tion are applied to determine the maximum deflection of the gate. Results show the capability of the model to efficiently quantify flood gate vibrations while considering the involved fluid-structure interaction. For the Afsluitdijk case this leads to a slightly lower maximum deflection of the gate, and therefore potentially al-lows a more economical design.Hydraulic Structures and Flood Ris
Inventory for a Reverse Journey. Photographic Image and Found Object - An investigation of travel and material transformation as a paradigm of artist's practice: Ed Ruscha, Douglas Huebler, Bas jan Ader, Jimmie Durham, Gustav Metzger, Kurt Schwitters & Cian Quayle.
Get PDFInventory for Reverse Journey is the title of a collection of photographic artefacts and found objects, which I have collected over the last twenty years. The title refers to one specific type of artist's journey, which is applicable to the `chronotope' of my archive, as a `metaphorical journey in space and time' (Bakhtin 1981, p. 81). The `city',`provincial town', `road', `threshold' and `interior' are recurrent motifs, which Bakhtin fused together to describe the historical evolution of the novel in relation to its different genres. Bakhtin's motifs are expanded as the basis of an evolutionary nomenclature of the artist's-journey, as a form of spatial mapping and identity formation. Alongside other sources from literature (Alain Robbe-Grillet), cinema (Michelangelo Antonioni), psychoanalysis (Kierkegaard) and critical theory (Walter Benjamin) I have developed a theoretical framework, which initially originated in an empirical process, that is reflected in the antecedents of this project. The research process, as a journey itself, has concretised this approach within a systems-based practice. This is mirrored in the work of the artists under investigation, as their differences and similarities are highlighted within a broad contextual analysis. Accordingly the tone of the writing shifts its register at different points in the thesis.
My journey is just one example of several paradigmatic formations of `travel' as a strategy, which investigates the work of six different artists, as a voluntary or involuntary form of exile. A deskilled use of the photographic image is examined in the work of Ed Ruscha, Douglas Huebler and Bas jan Ader in the spatial mapping of their chosen locations. The work of these artists manifests travel, as a strategy, in a benign form of regional and expatriate exile. The investigation shifts its focus from the New World to Europe, where the work of Jimmie Durham, Gustav Metzger and Kurt Schwitters is analysed in relation to their transformation of found objects and materials, and their relationship with a former 'home'. Their position registers different degrees of the `impossibility of return' to a point of origin, which exists in the mind rather than as a physical location. The transience of their work, and use of disparate materials, is counterbalanced by their physical presence in the work. Conversely Ader, Huebler and Ruscha are linked by a scale of decreasing visibility, as they are sublimated within their work in the formation of, what is now construed as, a unique photographic presence. The starting point for which is a return to the formative years of conceptualism in the 1960's, which set the scene for Durham and Metzger from the 1970's onwards. The spectre of Schwitters practice of forming (Formung) and unforming (Entformung) is significant for my analysis of the dematerialisation of the art-work and artist, by processes of series and repetition, distance and proximity, movement and stasis. Although `travel' is a ubiquitous term, I continue to use it as a portmanteau, which carries with it the themes and `salient' features of a typology of artist's journeys. In a moment of perceived obsolescence as digital information systems engender a culture of `selective-amnesia', these thoughts have informed my work, which runs parallel to the artist case-studies, and the material transformation of the photographic image and found object
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