TU Delft Repository

This study investigates the effect of driftwood on submerged culverts through scale experiments, focusing on their accumulation and the hydrodynamic processes occurring underneath. Examining temporal evolution and velocity measurements, this research delves into the implications of driftwood accumulation, including its geometry, hydraulic conditions and associated backwater rise. Findings reveal that accumulation shape is strongly influenced by hydraulic conditions, with higher Froude numbers pulling logs toward the bottom and thus yielding more compact accumulations. This effect holds implications for submerged culverts, where the opening near the bottom diminishes the importance of surface flow resistance. Accurate prediction of accumulation lengths is achieved using wood volume and initial flow velocity. The study also provides valuable data for developing quantitative design equations for backwater rise from driftwood accumulation at culverts. Additionally, detailed measurements of velocity profiles and Reynolds stresses under the accumulations highlight a slightly lower flow velocity, prompting the need for future research to discern its generality and implications for driftwood-induced scour at submerged culverts.

This study examines how citizen engagement strategies can facilitate more inclusive participation for enhancing liveability in urban area development. With growing demands for citizen involvement in decision-making processes, particularly in light of the new Environment and Planning Act, developers often face challenges such as increased objections, unrealistic expectations, and potential delays. This study aims to bridge the gap between theoretical research on citizen participation and practical challenges of engagement in urban development. It examines two case studies: the Defensie-eiland project in Woerden and the Piekstraat development in Rotterdam. The Defensie-eiland project has already implemented citizen engagement strategies during its transformation from a former military site into a mixed-use neighbourhood. The Piekstraat project, on the other hand, is an ongoing development aiming to revitalize a historic dockland area. The research uses a mixed-methods approach, including exploratory interviews, documentation analysis, in-depth stakeholder interviews and a validating citizen survey. The findings aim to contribute to the academic discourse on sustainable urban development by highlighting the importance of citizen participation in shaping liveable and inclusive neighbourhoods. The thesis concludes with recommendations for practitioners on how to implement the proposed strategies effectively, highlighting the need for context-specific approaches, transparent communication, and the use of hybrid participation models. Digital tools show the capacity to engage traditionally underrepresented groups more effectively. The plan's success hinges on a team with strong commitment and a clear objective.

Objective
Insight into the three-dimensional (3D) healthy growth of the radius and ulna remains limited, as orthopedics rely primarily on simple two-dimensional radiographic measurements. In this study, we used statistical shape modeling (SSM) to explore 3D forearm shape variations during healthy growth and predict individual radial and ulnar anatomy over time.

Methods
We trained SSMs using CT segmentations of 117 healthy radii and 116 ulnae. Principal Component Analysis (PCA), with and without Procrustes scaling, extracted general shape variation, while we used Partial Least Squares Regression (PLSR) to create an average growth model and prediction models. We developed several methods using age, sex, bone length and/or initial anatomy to predict bone anatomy over time. The models were validated by comparing the predicted bone models to the original segmentations of follow-up samples of 22 radii and 19 ulnae. The primary outcome measure was Root Mean Squared Error (RMSE), complemented by bone length error and mean and maximum distance errors.

Results
Size differences dominated the unscaled PCA- and PLSR-based SSMs, while the scaled PCA captured more subtle shape variations. With PLSR, we extracted the longitudinal growth trajectory for boys and girls aged 4 to 18 in 3D from the cross-sectional data. Using initial anatomy and age as input, the validation samples were predicted with RMSEs of less than 1 mm. The lowest bone length errors were reached using age, sex, and bone length as predictors.

Conclusion
We successfully utilized SSM to investigate and predict healthy growth of the radius and ulna in 3D. The current models are clinically viable as reference anatomy in pre-operative planning, and the methodology shows promise to support diagnosing and treating forearm deformities.

Let (S, Σ, μ) be a divisible measure space. Let F be a collection of subsets of S that are in Σ. For some applications it can be useful to describe the overlap between the sets in F. The sparse and Carleson constant both describe this overlap in a different way. The closer both of these constants are to 1, the closer the sets in F are to being pairwise disjoint. It has been shown that the sparse and Carleson condition are actually equivalent: we always have that F is Λ-Carleson if and only if F is Λ^-1-sparse. Proving that a Λ^-1-sparse collection is Λ-Carleson is quite simple, but proving that every Λ-Carleson collection also is Λ^-1-sparse turns out to be much harder. Previous proofs of the fact that Λ-Carleson are Λ^-1-sparse, such as the one by Hänninen [14] and Rey [25], have all relied on difficult theory. There is also no known method to exactly find the sets E_Q for each Q ∈ F that we need to satisfy the sparse condition. Rey is able to approximate these sets, but his algorithm has a logarithmic loss that can only be removed when imposing geometric restrictions.

In this paper I will give a proof of the equivalence of the sparse and Carleson condition for any finite collection F that relies only on basic set and optimisation theory. This proof can be extended to infinite collections F with only a minimal restriction. Asides from proving the equivalence, I also describe an algorithm that can find the sets E_Q for each Q ∈ F that we need to satisfy the sparse condition if F is finite and Carleson with respect to a divisible measure μ. Finally, I will describe an algorithm that we can use to find the Carleson constant of a finite collection F if it is unknown.

In response to the growing risks of pluvial flooding due to climate change, this thesis presents a framework to assess the resilience of urban drainage systems and guide adaptation strategies using coupled 1D-2D modelling and economic flood risk assessments. The research begins by exploring methods in InfoWorks ICM to simulate interactions between surface and subsurface flows in urban environments, focusing on a simplified approach to model gully flow that reduces data requirements and computational load. Building on this, flood hazards from the simplified model are used to identify buildings at risk of internal flooding, estimate potential financial losses, and calculate expected annual damages under current and future climate conditions, accounting for climate change impacts. Subsequently, this research evaluates blue, green, and grey infrastructure measures, through cost-benefit analysis where benefits are quantified as reductions in expected damages.

A detailed case study from Spangen, a densely populated residential area in Rotterdam, applies the proposed framework, demonstrating that a simplified 1D-2D modelling approach without individual gully data can realistically estimate pluvial flood hazards and support economic flood risk assessments. The findings of the risk assessment suggest that existing infrastructure investments in the neighborhood have effectively reduced current pluvial flood risks. Looking ahead, for future climate conditions, a combination of green, blue, and grey infrastructure proves to be the most effective adaptation strategy as these measures synergistically enhance the resilience. Despite this, the cost-benefit analysis revealed a negative net present value when considering only flood damage reduction due to low flood risks under current climate conditions. Nonetheless, comprehensive decision-making should account for the additional benefits of green infrastructure, such as urban cooling and associated energy savings, improved air quality, and enhanced biodiversity.