3,041 research outputs found
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
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
Salt marshes for flood risk reduction: Quantifying long-term effectiveness and life-cycle costs
Get PDFFlood risks are increasing worldwide due to climate change and ongoing economic and demographic development in coastal areas. Salt marshes can function as vegetated foreshores that reduce wave loads on coastal structures such as dikes and dams, thereby mitigating current and future flood risk. This paper aims to quantify long-term (100 years) flood risk reduction by salt marshes. Dike-foreshore configurations are assessed by coupled calculations of wave energy dissipation over the foreshore, sediment accretion under sea level rise, the probability of dike failure, and life-cycle costs. Rising sea levels lead to higher storm waves, and increasing probabilities of dike failure by wave overtopping. This study shows that marsh elevation change due to sediment accretion mitigates the increase in wave height, thereby elongating the lifetime of a dike-foreshore system. Further, different human interventions on foreshores are assessed in this paper: realization of a vegetated foreshore via nourishment, addition of a detached earthen breakwater, addition of an unnaturally high zone, or foreshore build-up by application of brushwood dams that enhance sediment accretion. The performance of these strategies is compared to dike heightening for the physical boundary conditions at an exposed dike along the Dutch Wadden Sea. Cost-effectiveness depends on three main factors. First, wave energy dissipation, which is lower for salt marshes with a natural elevation in the intertidal zone, when compared to foreshores with a high zone or detached breakwater. Second, required costs for construction and maintenance. Continuous maintenance costs and delayed effects on flood risk make sheltering structures less attractive from a flood risk perspective. Third, economic value of the protected area, where foreshores are particularly cost-effective for low economic value. Concluding, life-cycle cost analysis demonstrates that, within certain limits, foreshore construction can be more cost-effective than dike heightening.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 EngineeringHydraulic Structures and Flood Ris
Tidalgeopro
No full textThis is the version used by Roeland C. van de Vijsel in the paper "Vegetation controls on channel network complexity in coastal wetlands", by Roeland C. van de Vijsel, Jim van Belzen, Tjeerd J. Bouma, Daphne van der Wal, Bas W. Borsje, Stijn Temmerman, Loreta Cornacchia, Olivier Gourgue, and Johan van de Koppel, accepted in Nature Communications
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
SFERE
No full text<p>SFERE (Scale-dependent Feedback Recursion). Mathematical model to explain self-organization of complex spatial patterns from recursion of a scale-dependent feedback at multiple nested scales. First applied to self-organization of branching channel networks in coastal wetlands (van de Vijsel et al. 2023, Nature Communications).</p><p>This is SFERE v1.0, i.e. the original version of the model, which is used in the manuscript (van de Vijsel et al. 2023, Nature Communications). Please cite this model version as: van de Vijsel, R.C., van Belzen, J., Bouma, T.J., van der Wal, D., Borsje, B.W., Temmerman, S., Cornacchia, L., Gourgue, O., van de Koppel, J. (2023). SFERE (v1.0). Zenodo. https://doi.org/10.5281/zenodo.8428792.</p><p>The full dataset and its readme file, underlying the manuscript (van de Vijsel et al. 2023, Nature Communications) contains more information about SFERE. It can be found via <a href="https://doi.org/10.4121/8d361887-ec02-4472-a8eb-a9d0f3eacfd6">https://doi.org/10.4121/8d361887-ec02-4472-a8eb-a9d0f3eacfd6</a>.</p><p>References:</p><p>van de Vijsel, R.C., van Belzen, J., Bouma, T.J., van der Wal, D., Borsje, B.W., Temmerman, S., Cornacchia, L., Gourgue, O., van de Koppel, J. Vegetation controls on channel network complexity in coastal wetlands. Nature Commununications 14, 7158 (2023). https://doi.org/10.1038/s41467-023-42731-3.</p>
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
Living Dikes voor de ‘erfvijand van eeuwen’: Groningers en de kust in een diachroon perspectief
No full textRetour d\u92expériences après la tempête Xynthia en France, leçons pour les Pays Bas; les dégâts suite à l\u92inondation
No full textLe 28 février 2010, vers 2 heures du matin, la tempête Xynthia atteint la côte occidentale de la France. A plusieurs endroits, les digues, dunes et d\u92autres ouvrages cédèrent, donnant lieu à des inondations du littoral. Plus de 50.000 hectares de terres furent inondées. Au total, la France compta 47 morts suite à la tempête, la plupart d\u92entre eux suite à la crue. Essentiellement les régions de la Vendée et de la Charente-Maritime endurèrent de terribles privations. Les dégâts et les victimes ne sont pas uniquement la conséquence du phénomène naturel, mais également des interventions de l\u92homme ou le manque de celles-ci. Les Pays-Bas pourraient tirer des leçons de ces inondations côtières françaises. Les circonstances aux Pays-Bas et en France sont, dans une grande mesure, comparables. La France, elle aussi, connaît des zones côtières à basse altitude sensibles aux inondations. Certes, le niveau de protection aux Pays-Bas est plus élevé, mais une inondation aux Pays-Bas est aussi bien concevable. Tout comme en France, une inondation du littoral néerlandais est causée par une combinaison de la marée, d\u92une tempête et d\u92une surcote. Les législations et les réglementations présentent des concordances ; leurs bases datent de l\u92époque de Napoléon. Ce livre décrit l\u92inondation par la tempête Xynthia et ses conséquences. Nous en tirons des leçons et nous formulons des avis pour les Pays-Bas. Nous cherchons à nous associer à une protection contre l\u92inondation à trois volets: la prévention, l\u92aménagement du territoire et la maîtrise des catastrophes
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