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Backward erosion piping (BEP) is a failure mechanism of hydraulic structures like dams and levees on cohesionless foundations subjected to seepage flows. This article models the time-dependent development of BEP using numerical simulation of the erosion process. A 3-dimensional finite element equilibrium BEP model is extended with a formulation for the sediment transport rate. The model is compared to and calibrated with small- and large-scale experiments. Finally, a large set of simulations is analyzed to study the effects of factors such as grain size, scale (seepage length) and overloading on the rate of pipe progression. The results show that the development of BEP in the small-scale experiments is predicted well. Challenges remain for the prediction at larger scales, as calibration and validation is hard due to limited large-scale experiments with sufficiently accurate measurements. The results show that the progression rate increases with grain size and degree of overloading and decreases with seepage length, which is consistent with experimental observations. The model results provide a better physical basis for incorporating time-dependent development in the risk assessment and design of levees., Hydraulic Structures and Flood Risk

During the July 2021 Flood, the main flood defences along the River Meuse in the Netherlands performed well and did not breach. This paper is meant to document the various incidents on the flood defence system. As such, it provides an overview and description of the reported incidents related to flood defences, including a few breaches in minor flood defences. The incidents include overflow of embankments, sand boils, internal erosion at structures, and damage to a large weir and an outflow structure. Also, two local flood defences breached: an emergency embankment at Horn and an embankment in Roermond. During the event, the media reported on a dike breach at Meerssen/Bunde, however, after further investigation, it appeared that the concentrated outflow there was fuelled from a forgotten buried culvert., Hydraulic Structures and Flood Risk

Cell counting is a vital practice in the maintenance and manipulation of cell cultures. It is a crucial aspect of assessing cell viability and determining proliferation rates, which are integral to maintaining the health and functionality of a culture. Additionally, it is critical for establishing the time of infection in bioreactors and monitoring cell culture response to targeted infection over time. However, when cell counting is performed manually, the time involved can become substantial, particularly when multiple cultures need to be handled in parallel. Automated cell counters, which enable significant time reduction, are commercially available but remain relatively expensive. Here, we present a machine learning (ML) model based on YOLOv4 that is able to perform cell counts with a high accuracy (>95%) for Trypan blue-stained insect cells. Images of two distinctly different cell lines, Trichoplusia ni (High FiveTM; Hi5 cells) and Spodoptera frugiperda (Sf9), were used for training, validation, and testing of the model. The ML model yielded F1 scores of 0.97 and 0.96 for alive and dead cells, respectively, which represents a substantially improved performance over that of other cell counters. Furthermore, the ML model is versatile, as an F1 score of 0.96 was also obtained on images of Trypan blue-stained human embryonic kidney (HEK) cells that the model had not been trained on. Our implementation of the ML model comes with a straightforward user interface and can image in batches, which makes it highly suitable for the evaluation of multiple parallel cultures (e.g. in Design of Experiments). Overall, this approach for accurate classification of cells provides a fast, bias-free alternative to manual counting., BN/Nynke Dekker Lab

The Dutch banking sector is mandated to identify and report transactions that may signify money laundering (ML) activities. Banks have been reliant on rule-based transaction monitoring (TM) systems that flag transactions exceeding predefined thresholds. While such systems are instrumental in filtering potential ML transactions, the inherently small prevalence rate of ML occurring in the vast majority of financial transactions causes these systems to produce only a limited number of flagged transactions. Furthermore, as flagged transactions are only those surpassing certain rule thresholds, the alerts are biased toward presumed risk distributions. Consequently, this causes the performance regarding transactions that go unreviewed but should have been flagged, so-called false negatives, to remain unknown. This lack of understanding is a critical gap in the efficacy of current anti-money laundering (AML) controls and motivates the need for better insights into this False Negative Rate (FNR). Addressing this critical need for enhanced discernment of FNR, this study aims to improve this knowledge gap by answering the following research question: ‘To what extent could a supervised machine learning classifier, when trained on historical alerts, assist Dutch banks in estimating the False Negative Rate of rule-based transaction monitoring systems concerning unreviewed transactions?’. To achieve this goal, this study adopts a mixed-methods research design by combining a literature review with seven interviews with domain specialists to acquire insights into transactional ML typologies and the underlying indicators and thresholds employed in existing rule-based TM systems. The study further extended to the development of eight different types of supervised machine learning classifiers, applied both using their default settings as well as with balancing measures in place when possible. These classifiers were trained on two synthetically generated datasets of both 180 million tr, Engineering and Policy Analysis

De Kennisregio aan Zee 2070 is een ruimtelijk-economische samenwerking tussen de steden Den Haag, Zoetermeer, Delft en Leiden, de provincie Zuid Holland en kennisinstellingen TU Delft, Universiteit Leiden en de Haagse Hogeschool. De missie: laat de economie bijdragen aan oplossingen voor maatschappelijke problemen; waar schaarse ruimte onze kennis en praktijk uitdaagt tot innovatieve oplossingen voor een veilige, gezonde en inclusieve leefomgeving. De samenwerking heeft tot doel bouwstenen te ontwikkelen voor een toekomstperspectief dat richting geeft aan de maatschappelijke en ruimtelijk-economische regionale ontwikkeling; een verbindend verhaal dat de organisaties aanzet tot langdurige samenwerking als basis voor een duurzame kennisecologie en brede welvaart. Maar hoe zit het kennisecosysteem van de Kennisregio aan Zee eigenlijk precies ruimtelijk in elkaar? En welke ruimtelijke condities zijn aanwezig en moeten verder ontwikkeld worden op de schaal van de regio? En wat betekent dit voor innovatiedistricten in bijv. Delft, Den Haag, Leiden en Zoetermeer? Hoe zit het met de regionale samenhang, diversiteit en complementariteit en waar zitten mogelijkheden voor verbetering? Hoe kan het landschap dienen als basis voor klimaat-adaptief en natuur-inclusieve ruimtelijke ontwikkeling gerelateerd aan bijvoorbeeld woningbouwopgave? Ondanks dat we hier nog niet alle antwoorden op hebben kunnen we wel een aantal ruimtelijke voorwaarden benoemen die de Kennisregio aan Zee 2070 productiever, sociaal en ecologisch inclusiever en toekomstbestendig maken; en slimme groei op de juiste plekken faciliteren. Deze publicatie beoogt een aantal ruimtelijke bouwstenen te benoemen en uit te werken in een regionaal ruimtelijk-economisch perspectief. Het natuurlijke landschap en de stedelijke context zijn de basis voor een duurzame kennisecologie en brede welvaart op de lange termijn. Centraal staat een eerste ruimtelijke verkenning, een regionaal ontwerp waarin wonen, m, TU Delft Landschapsarchitectuur, mmv OKRA landschapsarchitecten, Atlas Research, Global Institute of Technology, Landscape Architecture, Support Urbanism, Urban Design

Decentralised solar electricity generation on a large scale is a relatively new phenomenon. In the State of New York, the adoption of this form of renewable electricity generation has seen a surge over the last decade. However, policies that have been implemented over the last year, prompted experts to question the future of the market. The question is, what are the effects on energy security when these policies are in place? Using 3 relevant theories (TPB, VBN, and DOI) on household decision-making processes, a study of what is meant by decentralised solar and the context in which the market operates in the Empire State, I used an agent-based model to analyse the impacts of these policies in terms of energy security. Energy security is defined into 6 dimensions (Availability, Affordability, Accessibility, Acceptability, Ability, and Appeal). Experimentation and subsequent analysis showed a limited effect on most of these terms. However, a combination of these policies showed a less favourable effect on all scenarios as compared to the business-as-usual scenario. What was salient during experimentation was that the combination of the policies led to a difference in direction of the effects than when the effects of the policies implemented in isolation were added together. Indicating an inter-relationship between policies. Moreover, during market analysis it was found that the influence of the traditional utilities (owned by private investors) exert great influence on the policy making process, in their own favour. Based on this research, the future of decentralised solar electricity generation in the State of New York is going to be a tough battle with the greatest hurdle being overcoming the power of centralised utilities., Industrial Ecology

The Shields–Darcy (SD) model by Hoffmans and Van Rijn (Citation2018) describes the resistance of hydraulic structures to backward erosion piping, which is a form of internal erosion. In the article being discussed, Hoffmans compares the SD model to the model by Sellmeijer et al. (Citation2011), focusing on field scales. This Discussion presents finite element simulations that deviate from Hoffmans’ conclusions that the model by Sellmeijer et al. (Citation2011) results in an unrealistically low critical gradient. As both the SD and Sellmeijer models fit reasonably well to laboratory experiments (Hoffmans & Van Rijn, Citation2018), extrapolation to field scales (say aquifer thickness D > 5 m, seepage length L > 10 m) is important, particularly since these models are used for the design of flood defences. Hoffmans addresses this issue by analysing the resistance as function of aquifer depth D. Hoffmans recommends checking the outcomes of the SD model with a mathematical piping model like that of Van Esch et al. (Citation2013)., Hydraulic Structures and Flood Risk

Structural reliability analysis often considers failure mechanisms as correlated but non-interacting processes. Interacting failure mechanisms affect each others performance, and thereby the system reliability. We describe such interactions in the context of flood defenses, and analyze under which conditions such interactions have a large impact on reliability using a Monte Carlo-based quantification method. We provide simple examples and an application to levee failure due to landward slope instability and backward erosion piping (BEP). The examples show that the largest interaction effects are expected when the trigger mechanism is relatively likely to occur and the affected mechanism has a relatively large contribution to the system reliability. For the studied levee example, interactions between slope instability and BEP increased the failure probability up to a factor 4. Implications for the assessment and design of flood defenses are discussed., Hydraulic Structures and Flood Risk, Geo-engineering

Background: In hip arthroplasties, surgeons rely on their experience to assess the stability and balance of hip tissues when fitting the implant to their patients. During the operation, surgeons use a modular, temporary set of implants to feel the tension in the surrounding soft tissues and adjust the implant configuration. This process is naturally subjective and therefore depends on the operator. Inexperienced surgeons undertaking hip arthroplasties are twice as likely to experience errors than their experienced colleagues, leading to dislocations, pain and discomfort for the patients. Methods: To address this issue, a new, 3DOF force measurement system was developed and integrated into the modular, trial implants that can quantify forces and movements intraoperatively in 3D. The prototypes were evaluated in three post-mortem human specimens (PMHSs), to provide surgeons with objective data to help determine the optimal implant fit and configuration. The devices comprise a deformable polymer material providing strain-based displacements measured with electromagnetic-based sensors and an inertial measurement unit (IMU) for motion data. Results: Device results show a relative accuracy of approx. 2% and a sensitivity of approx. 1%. PMHS results indicated that soft tissue forces on the hip joint peak in the order of ~100 N and trend with positions of the leg during range of motion (ROM) tests, although force patterns differ between each PMHS. Conclusion: By monitoring forces and force patterns of hip soft tissues, in combination with standardised ROM tests, the force patterns could shed a light on potential anomalies that can be addressed during surgery. Clinical and Translational Impact Statement: The development of an instrumented hip implant device for use during surgery knowledge will eventually allow us to develop a predictive model for soft tissue balancing, that can be used for pre- and intra-operative planning for each patient on a tailored and personalised bas, Medical Instruments & Bio-Inspired Technology, Biomaterials & Tissue Biomechanics

Backward erosion piping (BEP) is a form of internal erosion which can lead to failure of levees and dams. Most research focused on the critical head difference at which piping failure occurs. Two aspects have received less attention, namely (1) the temporal evolution of piping and (2) the local hydraulic conditions in the pipe and at the pipe tip. We present small-scale experiments with local pressure measurements in the pipe during equilibrium and pipe progression for different sands and degrees of hydraulic loading. The experiments confirm a positive relation between progression rate and grain size as well as the degree of hydraulic overloading. Furthermore, the analysis of local hydraulic conditions shows that the rate of BEP progression can be better explained by the bed shear stress and sediment transport in the pipe than by the seepage velocity at the pipe tip. The experiments show how different processes contribute to the piping process and these insights provide a first empirical basis for modeling pipe development using coupled seepage-sediment transport equations., Hydraulic Structures and Flood Risk

Backward erosion piping (BEP) is a type of internal erosion responsible for the failure of many dams and levees. BEP occurs when small, shallow erosion channels progress upstream through foundation sands beneath the structure. As analysis of BEP involves coupling two different sets of flow equations to describe the groundwater flow and erosion pipe flow, the solution contains a singularity in the gradient field at the juncture of the soil and pipe domains. In addition, the erosion process is highly localized, often occurring over length scales of 1 cm or less. While it is well known that singularities and localized phenomena cause high errors in numerical solutions, there has been no assessment of the magnitude of these errors in BEP numerical models. This study evaluates the magnitude of error in BEP finite element models through comparison of numerical results to measurements from a highly instrumented BEP experiment. The results indicate that discretization errors related to the pipe geometry can cause 50%–300% error in the solution near the pipe tip when the pipe is represented via linear, 1D elements. These errors are significant and must be considered for models that assess pipe progression based on the local solution near the pipe tip. Results also indicate that the pipe width must be modeled as twice the physical pipe width to accurately represent the pipe flow when assuming a rectangular cross sectional shape for the erosion pipe., 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., Hydraulic Structures and Flood Risk

This paper presents the numerical interpretation of a recent experiment on a real-scale levee physical model, in order to investigate the process of Backward Erosion Piping (BEP) and validate a recently proposed finite element formulation able to model both the simultaneous processes observed in backward erosion piping, i.e. the propagation of the pipe tip and the enlargement of the conduit cross-section, as well as the time-dependent effects. In previous papers, the numerical formulation already demonstrated its ability in reproducing available experimental data of full-scale physical models of levees, e.g. for the IJkdijk and for the Delta Flume tests. In the present work, as a further validation for the aforementioned formulation, we consider the numerical interpretation of the regressive localized internal erosion observed in the newly constructed real-scale levee at the Flood Proof Holland facility test site in Delft, The Netherlands. This test was mainly focused on the experimental evaluation of the time-dependent effects typically observed in these phenomena. To this purpose the levee foundation was equipped with an effective and accurate pore water pressure monitoring system. The aforementioned formulation was considered for the numerical interpretation of the test, in view of its ability in modeling the time-dependent effects in backward erosion piping. Indeed, a good agreement between calculated and measured piezometric heads and pipe tip propagations was obtained., 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., Hydraulic Structures and Flood Risk

Hydraulic Structures and Flood Risk

Structural flood protection systems such as levees are an important component in flood risk reduction strategies. Levees can fail through various failure mechanisms; this thesis focuses on the mechanism Backward Erosion Piping (BEP) which occurs when a sandy levee foundation is eroded by groundwater flow. To assess whether a levee's reliability complies with safety standards, authorities use models which describe the levee properties and failure mechanisms. This thesis aims to extend the current failure model by considering piping as a time-dependent erosion process instead of the current assumption of immediate failure once a critical threshold is exceeded. Therefore, it is shown how time-dependent development of backward erosion piping can be quantified and how it affects levee reliability analyses. This is achieved by a combination of literature review, analysis of previous experiments, additional experiments on different scales, numerical modeling and probabilistic modeling. The following key findings were established. Analysis of historical levee failures due to BEP and previous experiments indicates that there can be significant time between initiation and breach, highlighting the importance of time-dependence for piping. The rate of pipe progression in experiments can be explained by the sediment transport rate, which is shown to depend on the pipe flow conditions. A numerical groundwater flow model which includes this sediment transport process can predict the pipe development in small-scale experiments. Relations between the progression rate and levee properties and hydraulic loads as derived with this numerical model can be used efficiently in reliability analyses. These analyses show that including time-dependent pipe development in BEP analyses has a significant impact on the levee failure probability, both in coastal and riverine water systems., Hydraulic Structures and Flood Risk

Background: In hip arthroplasties, surgeons rely on their experience to assess the stability and balance of hip tissues when fitting the implant to their patients. During the operation, surgeons use a modular, temporary set of implants to feel the tension in the surrounding soft tissues and adjust the implant configuration. This process is naturally subjective and therefore depends on the operator. Inexperienced surgeons undertaking hip arthroplasties are twice as likely to experience errors than their experienced colleagues, leading to dislocations, pain and discomfort for the patients. Methods: To address this issue, a new, 3DOF force measurement system was developed and integrated into the modular, trial implants that can quantify forces and movements intraoperatively in 3D. The prototypes were evaluated in three post-mortem human specimens (PMHSs), to provide surgeons with objective data to help determine the optimal implant fit and configuration. The devices comprise a deformable polymer material providing strain-based displacements measured with electromagnetic-based sensors and an inertial measurement unit (IMU) for motion data. Results: Device results show a relative accuracy of approx. 2% and a sensitivity of approx. 1%. PMHS results indicated that soft tissue forces on the hip joint peak in the order of ~100 N and trend with positions of the leg during range of motion (ROM) tests, although force patterns differ between each PMHS. Conclusion: By monitoring forces and force patterns of hip soft tissues, in combination with standardised ROM tests, the force patterns could shed a light on potential anomalies that can be addressed during surgery. Clinical and Translational Impact Statement: The development of an instrumented hip implant device for use during surgery knowledge will eventually allow us to develop a predictive model for soft tissue balancing, that can be used for pre- and intra-operative planning for each patient on a tailored and personalised bas, Medical Instruments & Bio-Inspired Technology, Biomaterials & Tissue Biomechanics

Backward erosion piping (BEP) is a form of internal erosion which can lead to failure of levees and dams. Most research focused on the critical head difference at which piping failure occurs. Two aspects have received less attention, namely (1) the temporal evolution of piping and (2) the local hydraulic conditions in the pipe and at the pipe tip. We present small-scale experiments with local pressure measurements in the pipe during equilibrium and pipe progression for different sands and degrees of hydraulic loading. The experiments confirm a positive relation between progression rate and grain size as well as the degree of hydraulic overloading. Furthermore, the analysis of local hydraulic conditions shows that the rate of BEP progression can be better explained by the bed shear stress and sediment transport in the pipe than by the seepage velocity at the pipe tip. The experiments show how different processes contribute to the piping process and these insights provide a first empirical basis for modeling pipe development using coupled seepage-sediment transport equations., Hydraulic Structures and Flood Risk

Most research on backward erosion piping (BEP) focuses on the critical conditions leading to failure. This paper studies the development of piping over time once the critical conditions are exceeded, which is useful to estimate time to failure. A commonly used small scale rectangular box setup is modified in order to monitor pore pressures and pipe pressures with a high spatial and temporal resolution. The experimental program includes three different sand types to study the effects of grain size and compaction, and different degrees of hydraulic loading. The results indicate that the transport of particles in the pipe affects the progression rate, and that the progression rate is related to the bed shear stress in the pipe., Hydraulic Structures and Flood Risk

In 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 (Deltare, Hydraulic Structures and Flood Risk, Safety and Security Science, Coastal Engineering

Architecture, Urbanism and Building Sciences

The Multi-farm was designed in such a way that it forms a valuable link in a new neighbourhood's (in the Cornelis-Douwes 01 area in Amsterdam) social and ecological system. In the research strategies were developed for a decentral organisation of local foodproduction and waterpurification in a new neighbourhood, but the research also provided insight into how these could be organised to provide mental health benefits as well to those living in the new neighbourhood whom are in demand of it. The Multi-farm was designed as a nature based mental healthcare facility with a partly public program that promotes sustainable food (production) but also offers safe spaces (closed of from the public) where people with severe mental health issues can farm. For these people farming is seen as a valuable taks which can help them gain new self confidence that they (to some exent) lost due to their mental issues and can therefore help them to integrate into the neighbourhood's social system. Thus the design contributes to the social sustainablity of the neighbourhood but also to the environmental sustainablity as the food and water strategies have a positive impact on the neighbourhoods ecosystems., Architecture, Urbanism and Building Sciences | Management in the Built Environment

This paper presents a large-scale backward erosion piping experiment aimed at studying the erosion rate. This temporal aspect of piping complements previous research that focused on the critical head. To study the progression rate in realistic conditions, an experiment was carried out on a 1.8 m high levee with a cohesive blanket on a sandy foundation. The pipe was guided along a row of pore pressure transducers in order to measure its temporal development. Pipe development in space and time was successfully derived from pore pressure changes, showing an average progression rate of 8 m/day during the progressive erosion phase. The results show a relation between upstream gradient and progression rate. Furthermore, analysis of the eroded sand mass shows a relatively large pipe volume compared to existing lab tests, and an approximately linear relation between pipe length and volume. The results and insights from this study can be used to validate and improve transient piping models, leading to more accurate dam and levee safety assessments., 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., Hydraulic Structures and Flood Risk

Most research on backward erosion piping (BEP) focuses on the critical conditions leading to failure. This paper studies the development of piping over time once the critical conditions are exceeded, which is useful to estimate time to failure. A commonly used small scale rectangular box setup is modified in order to monitor pore pressures and pipe pressures with a high spatial and temporal resolution. The experimental program includes three different sand types to study the effects of grain size and compaction, and different degrees of hydraulic loading. The results indicate that the transport of particles in the pipe affects the progression rate, and that the progression rate is related to the bed shear stress in the pipe., Hydraulic Structures and Flood Risk

In 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 (Deltare, Hydraulic Structures and Flood Risk, Safety and Security Science, Coastal Engineering

This paper presents a large-scale backward erosion piping experiment aimed at studying the erosion rate. This temporal aspect of piping complements previous research that focused on the critical head. To study the progression rate in realistic conditions, an experiment was carried out on a 1.8 m high levee with a cohesive blanket on a sandy foundation. The pipe was guided along a row of pore pressure transducers in order to measure its temporal development. Pipe development in space and time was successfully derived from pore pressure changes, showing an average progression rate of 8 m/day during the progressive erosion phase. The results show a relation between upstream gradient and progression rate. Furthermore, analysis of the eroded sand mass shows a relatively large pipe volume compared to existing lab tests, and an approximately linear relation between pipe length and volume. The results and insights from this study can be used to validate and improve transient piping models, leading to more accurate dam and levee safety assessments., 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., Hydraulic Structures and Flood Risk

The Multi-farm was designed in such a way that it forms a valuable link in a new neighbourhood's (in the Cornelis-Douwes 01 area in Amsterdam) social and ecological system. In the research strategies were developed for a decentral organisation of local foodproduction and waterpurification in a new neighbourhood, but the research also provided insight into how these could be organised to provide mental health benefits as well to those living in the new neighbourhood whom are in demand of it. The Multi-farm was designed as a nature based mental healthcare facility with a partly public program that promotes sustainable food (production) but also offers safe spaces (closed of from the public) where people with severe mental health issues can farm. For these people farming is seen as a valuable taks which can help them gain new self confidence that they (to some exent) lost due to their mental issues and can therefore help them to integrate into the neighbourhood's social system. Thus the design contributes to the social sustainablity of the neighbourhood but also to the environmental sustainablity as the food and water strategies have a positive impact on the neighbourhoods ecosystems., Architecture, Urbanism and Building Sciences | Management in the Built Environment

Architecture, Urbanism and Building Sciences

This paper introduces MDP homomorphic networks for deep reinforcement learning. MDP homomorphic networks are neural networks that are equivariant under symmetries in the joint state-action space of an MDP. Current approaches to deep reinforcement learning do not usually exploit knowledge about such structure. By building this prior knowledge into policy and value networks using an equivariance constraint, we can reduce the size of the solution space. We specifically focus on group-structured symmetries (invertible transformations). Additionally, we introduce an easy method for constructing equivariant network layers numerically, so the system designer need not solve the constraints by hand, as is typically done. We construct MDP homomorphic MLPs and CNNs that are equivariant under either a group of reflections or rotations. We show that such networks converge faster than unstructured baselines on CartPole, a grid world and Pong., Interactive Intelligence

Hydraulic Structures and Flood Risk

This work exploits action equivariance for representation learning in reinforcement learning. Equivariance under actions states that transitions in the input space are mirrored by equivalent transitions in latent space, while the map and transition functions should also commute. We introduce a contrastive loss function that enforces action equivariance on the learned representations. We prove that when our loss is zero, we have a homomorphism of a deterministic Markov Decision Process (MDP). Learning equivariant maps leads to structured latent spaces, allowing us to build a model on which we plan through value iteration. We show experimentally that for deterministic MDPs, the optimal policy in the abstract MDP can be successfully lifted to the original MDP. Moreover, the approach easily adapts to changes in the goal states. Empirically, we show that in such MDPs, we obtain better representations in fewer epochs compared to representation learning approaches using reconstructions, while generalizing better to new goals than model-free approaches., Interactive Intelligence

The project named production biospheres created a process design aimed on the adaptive reuse of the Plots In The Woods site on the Hembrug terrain near Zaandam. The landscape and urban design for the site is based on methods used by landscape architects and ecologists based on the three terms cultivate, stage and set up, not just creating. The process design is adding to redevelopment activities already done on site. A small cultural program and a used (wood) building material warehouse and workshop are added reacting no the existing program, mainly being creative businesses, like contractors, artists, designers and other makers. The specific building design concepts are based on the concepts and themes discussed in the Venice Biennale catalogue for the German pavillion in 2012 titled: Reduce, Reuse Recycle. These approaches are applied in the different phases the buildings and spatial elements are in based on the cultural values assigned and researched during the P1 phase. This gradution project under the department of Heritage & Architecture results in a process design for part of the Hembrug area which is still in a fragile state of development., Revitalising Heritage, Revitalising heritage: Hembrug, Architecture, Urbanism and Building Sciences | Heritage & Architecture

This paper introduces MDP homomorphic networks for deep reinforcement learning. MDP homomorphic networks are neural networks that are equivariant under symmetries in the joint state-action space of an MDP. Current approaches to deep reinforcement learning do not usually exploit knowledge about such structure. By building this prior knowledge into policy and value networks using an equivariance constraint, we can reduce the size of the solution space. We specifically focus on group-structured symmetries (invertible transformations). Additionally, we introduce an easy method for constructing equivariant network layers numerically, so the system designer need not solve the constraints by hand, as is typically done. We construct MDP homomorphic MLPs and CNNs that are equivariant under either a group of reflections or rotations. We show that such networks converge faster than unstructured baselines on CartPole, a grid world and Pong., Interactive Intelligence

Hydraulic Structures and Flood Risk

This work exploits action equivariance for representation learning in reinforcement learning. Equivariance under actions states that transitions in the input space are mirrored by equivalent transitions in latent space, while the map and transition functions should also commute. We introduce a contrastive loss function that enforces action equivariance on the learned representations. We prove that when our loss is zero, we have a homomorphism of a deterministic Markov Decision Process (MDP). Learning equivariant maps leads to structured latent spaces, allowing us to build a model on which we plan through value iteration. We show experimentally that for deterministic MDPs, the optimal policy in the abstract MDP can be successfully lifted to the original MDP. Moreover, the approach easily adapts to changes in the goal states. Empirically, we show that in such MDPs, we obtain better representations in fewer epochs compared to representation learning approaches using reconstructions, while generalizing better to new goals than model-free approaches., Interactive Intelligence

The project named production biospheres created a process design aimed on the adaptive reuse of the Plots In The Woods site on the Hembrug terrain near Zaandam. The landscape and urban design for the site is based on methods used by landscape architects and ecologists based on the three terms cultivate, stage and set up, not just creating. The process design is adding to redevelopment activities already done on site. A small cultural program and a used (wood) building material warehouse and workshop are added reacting no the existing program, mainly being creative businesses, like contractors, artists, designers and other makers. The specific building design concepts are based on the concepts and themes discussed in the Venice Biennale catalogue for the German pavillion in 2012 titled: Reduce, Reuse Recycle. These approaches are applied in the different phases the buildings and spatial elements are in based on the cultural values assigned and researched during the P1 phase. This gradution project under the department of Heritage & Architecture results in a process design for part of the Hembrug area which is still in a fragile state of development., Revitalising Heritage, Revitalising heritage: Hembrug, Architecture, Urbanism and Building Sciences | Heritage & Architecture

Backward erosion piping is an important failure mode of dikes and dams. The time required for the backward erosion process to result in dike failure is expected to be an important factor in the safety of dikes. This holds especially in coastal and estuarine areas which are dominated by storm surge, and pipes may not fully develop during a storm. Furthermore, insight in the duration of the various piping stages can assist in developing effective emergency mitigation measures. However, the temporal development of piping is hardly studied quantitatively, as most experimental and modelling studies focus on the critical head. Also data of real breaches is generally insufficient to determine the time to failure. As a result, currently the contribution of time required for pipe growth cannot be quantified in a deterministic and reliability analysis. In this study, it is investigated how the pipe progression rate can be predicted and applied to dike reliability. The data analysis is based on a composition of 45 small, medium and large scale experiments from six studies. Advancement rates are related to the applied hydraulic gradient and soil properties using a multivariate analysis. From the analysis we derive an empirical model for the advancement rate, including a quantification of the uncertainty. This model is applied in a reliability analysis of a hypothetical coastal and riverine dike. The results of our analysis may be used to validate transient numerical piping models, perform time-dependent probabilistic dike safety analysis and support emergency response., 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., Hydraulic Structures and Flood Risk

Save for some special cases, current training methods for Generative Adversarial Networks (GANs) are at best guaranteed to converge to a ‘local Nash equilibrium’ (LNE). Such LNEs, however, can be arbitrarily far from an actual Nash equilibrium (NE), which implies that there are no guarantees on the quality of the found generator or classifier. This paper proposes to model GANs explicitly as finite games in mixed strategies, thereby ensuring that every LNE is an NE. We use the Parallel Nash Memory as a solution method, which is proven to monotonically converge to a resource-bounded Nash equilibrium. We empirically demonstrate that our method is less prone to typical GAN problems such as mode collapse and produces solutions that are less exploitable than those produced by GANs and MGANs., 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., Interactive Intelligence

Apart from the soil erodibility parameter, the critical shear stress is the most important parameter in predicting erosion rates. On the basis of experiments several empirical formulas have already been de-veloped which relate the critical shear stress to soil properties. Based on these findings and supported by new large scale experiments, a new predictive relation between the critical shear stress and soil properties is proposed here. In support of this study, Delft University of Technology collaborated with Saitama University in the preparation and execution of a large scale levee erosion experiment in Janu-ary 2019. The erosion experiments were performed in the on a 1.8m high levee with a sand core and respectively clay and loam cover types. The cover types were subjected to a constant overflow dis-charge of approximately 70 l/m/s. The test levee was constructed in the Flood Proof Holland test pol-der in Delft, The Netherlands. During the experiment, time lapse measurements of the erosion depth were obtained at 15 locations along the landside slope. Before and after overflow tests were performed on each cover type, soil samples were collected along the landside slope at 8 locations. This paper out-lines how these large experiments were used to evaluate the effectiveness and application limit of the new predictive equation for the critical shear stress. A comparison between the predicted and meas-ured erosion rates shows that by applying the new empirical relation for the critical shear stress, meas-ured erosion rates could be predicted around ±30 % errors., Hydraulic Structures and Flood Risk

In the oil and gas industry the occurrence of slug flow in flowlines and risers can cause operational problems. Such flowline-riser systems are used to transport the oil and/or gas from the location of the wells to a production platform, where the fluids might be separated into single phases. Slug flow conditions imposefluctuations in the production rate, which may lead to the flooding of the separators, trips of compressors or pumps, and to increased loads on the supports of the pipeline and piping sections at the production platform.Therefore, measures have to be taken to mitigate the slugging, which can be a reduction of the production rate, making adjustments to the pipeline system, or adding surfactants to the flow. For vertical flow in production wells, the use of surfactants is a proven technology. Here the creation of a foam through adding asurfactant can increase the production life time, as the accumulation of liquid, which typically occurs when the reservoir pressure has decreased at the end of field life, is prevented. Far less is known yet about the effect of using surfactants for the mitigation of hydrodynamic slugs in a nearly horizontal flowline or the mitigation of severe slugs in risers. From a previous Master’s Thesis project by Pronk [1], in which lab experiments were carried out in the same flowline-riser facility as used in the present study, it was concluded that growing slugs could be suppressed by adding a surfactant to create foam. The surfactants also influence the characteristics of the severe slugging cycle, but they are not able to fully suppress it. Re-analysis of the measurement data by Pronk hasturned out that instead of growing slugs, severe sluggingwas measured and therefore that severe slugging can be suppressed using surfactants and no conclusions can be drawn on growing slugs or hydrodynamic slugsfrom her research. There is limited literature on the effect of adding a surfactant to hydrodynamic slug flow in horizontal flowlines

Backward erosion piping is an important failure mode of dikes and dams. The time required for the backward erosion process to result in dike failure is expected to be an important factor in the safety of dikes. This holds especially in coastal and estuarine areas which are dominated by storm surge, and pipes may not fully develop during a storm. Furthermore, insight in the duration of the various piping stages can assist in developing effective emergency mitigation measures. However, the temporal development of piping is hardly studied quantitatively, as most experimental and modelling studies focus on the critical head. Also data of real breaches is generally insufficient to determine the time to failure. As a result, currently the contribution of time required for pipe growth cannot be quantified in a deterministic and reliability analysis. In this study, it is investigated how the pipe progression rate can be predicted and applied to dike reliability. The data analysis is based on a composition of 45 small, medium and large scale experiments from six studies. Advancement rates are related to the applied hydraulic gradient and soil properties using a multivariate analysis. From the analysis we derive an empirical model for the advancement rate, including a quantification of the uncertainty. This model is applied in a reliability analysis of a hypothetical coastal and riverine dike. The results of our analysis may be used to validate transient numerical piping models, perform time-dependent probabilistic dike safety analysis and support emergency response., 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., Hydraulic Structures and Flood Risk

Save for some special cases, current training methods for Generative Adversarial Networks (GANs) are at best guaranteed to converge to a ‘local Nash equilibrium’ (LNE). Such LNEs, however, can be arbitrarily far from an actual Nash equilibrium (NE), which implies that there are no guarantees on the quality of the found generator or classifier. This paper proposes to model GANs explicitly as finite games in mixed strategies, thereby ensuring that every LNE is an NE. We use the Parallel Nash Memory as a solution method, which is proven to monotonically converge to a resource-bounded Nash equilibrium. We empirically demonstrate that our method is less prone to typical GAN problems such as mode collapse and produces solutions that are less exploitable than those produced by GANs and MGANs., 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., Interactive Intelligence

Apart from the soil erodibility parameter, the critical shear stress is the most important parameter in predicting erosion rates. On the basis of experiments several empirical formulas have already been de-veloped which relate the critical shear stress to soil properties. Based on these findings and supported by new large scale experiments, a new predictive relation between the critical shear stress and soil properties is proposed here. In support of this study, Delft University of Technology collaborated with Saitama University in the preparation and execution of a large scale levee erosion experiment in Janu-ary 2019. The erosion experiments were performed in the on a 1.8m high levee with a sand core and respectively clay and loam cover types. The cover types were subjected to a constant overflow dis-charge of approximately 70 l/m/s. The test levee was constructed in the Flood Proof Holland test pol-der in Delft, The Netherlands. During the experiment, time lapse measurements of the erosion depth were obtained at 15 locations along the landside slope. Before and after overflow tests were performed on each cover type, soil samples were collected along the landside slope at 8 locations. This paper out-lines how these large experiments were used to evaluate the effectiveness and application limit of the new predictive equation for the critical shear stress. A comparison between the predicted and meas-ured erosion rates shows that by applying the new empirical relation for the critical shear stress, meas-ured erosion rates could be predicted around ±30 % errors., Hydraulic Structures and Flood Risk

In the oil and gas industry the occurrence of slug flow in flowlines and risers can cause operational problems. Such flowline-riser systems are used to transport the oil and/or gas from the location of the wells to a production platform, where the fluids might be separated into single phases. Slug flow conditions imposefluctuations in the production rate, which may lead to the flooding of the separators, trips of compressors or pumps, and to increased loads on the supports of the pipeline and piping sections at the production platform.Therefore, measures have to be taken to mitigate the slugging, which can be a reduction of the production rate, making adjustments to the pipeline system, or adding surfactants to the flow. For vertical flow in production wells, the use of surfactants is a proven technology. Here the creation of a foam through adding asurfactant can increase the production life time, as the accumulation of liquid, which typically occurs when the reservoir pressure has decreased at the end of field life, is prevented. Far less is known yet about the effect of using surfactants for the mitigation of hydrodynamic slugs in a nearly horizontal flowline or the mitigation of severe slugs in risers. From a previous Master’s Thesis project by Pronk [1], in which lab experiments were carried out in the same flowline-riser facility as used in the present study, it was concluded that growing slugs could be suppressed by adding a surfactant to create foam. The surfactants also influence the characteristics of the severe slugging cycle, but they are not able to fully suppress it. Re-analysis of the measurement data by Pronk hasturned out that instead of growing slugs, severe sluggingwas measured and therefore that severe slugging can be suppressed using surfactants and no conclusions can be drawn on growing slugs or hydrodynamic slugsfrom her research. There is limited literature on the effect of adding a surfactant to hydrodynamic slug flow in horizontal flowlines

The goal of this thesis is: ''To create a sterilizable instrument that measures the compressive force in the axial direction of the neck of the hip implant during surgery''. This measured axial force in combination with a standardized ROM test could be used to objectively assess the soft tissue tension during surgery. It is expected that this instrument will be a helpful tool for inexperienced surgeons, because literature shows that errors made by the surgeon are the biggest cause of early failures and inexperienced surgeons registered twice as much dislocations as experienced surgeons. Therefore, the instrument could improve the success rate and quality of total hip arthroplasty by reducing the number of early failures caused by dislocation resulting from the inadequate soft tissue tension created by inexperienced surgeons. Furthermore, it could improve the patients' quality of living by reducing their limping and pain after the surgery. The current techniques to obtain the optimal length and angle of the implant are: preoperative radiography, intraoperative leg length assessment and subjective soft tissue tension assessment methods. Factors that influence soft tissue tension, apart from the implant, are either caused by the patient (inter- or intra-personal), the surgeon or the environment. Although a 3 DOF sensory system integrated in the test stem is preferable, it is likely that measuring only the axial force in a so called 'the neck' of the prosthesis, in combination with a standardized range of motion (ROM) test, provides valuable inside information about the relation between variation in force and success of the procedure. This assessment is not based measuring absolute forces, but on pattern recognition while moving the hip through its range of motion. The validity of this hypothesis should be investigated in future research. Different sensors have been tested to see if they survive the standard sterilization program of an autoclave, which uses

Technology, Policy and Management, Systems Engineering, Policy Analysis and Management (SEPAM)

The goal of this thesis is: ''To create a sterilizable instrument that measures the compressive force in the axial direction of the neck of the hip implant during surgery''. This measured axial force in combination with a standardized ROM test could be used to objectively assess the soft tissue tension during surgery. It is expected that this instrument will be a helpful tool for inexperienced surgeons, because literature shows that errors made by the surgeon are the biggest cause of early failures and inexperienced surgeons registered twice as much dislocations as experienced surgeons. Therefore, the instrument could improve the success rate and quality of total hip arthroplasty by reducing the number of early failures caused by dislocation resulting from the inadequate soft tissue tension created by inexperienced surgeons. Furthermore, it could improve the patients' quality of living by reducing their limping and pain after the surgery. The current techniques to obtain the optimal length and angle of the implant are: preoperative radiography, intraoperative leg length assessment and subjective soft tissue tension assessment methods. Factors that influence soft tissue tension, apart from the implant, are either caused by the patient (inter- or intra-personal), the surgeon or the environment. Although a 3 DOF sensory system integrated in the test stem is preferable, it is likely that measuring only the axial force in a so called 'the neck' of the prosthesis, in combination with a standardized range of motion (ROM) test, provides valuable inside information about the relation between variation in force and success of the procedure. This assessment is not based measuring absolute forces, but on pattern recognition while moving the hip through its range of motion. The validity of this hypothesis should be investigated in future research. Different sensors have been tested to see if they survive the standard sterilization program of an autoclave, which uses

Technology, Policy and Management, Systems Engineering, Policy Analysis and Management (SEPAM)

Software is widely used, and society increasingly depends on its reliability. However, software has become so complex and it evolves so quickly that we fail to keep it under control. Therefore, we propose intents: fundamental laws that capture a software systems’ intended behavior (resilient, secure, safe, sustainable, etc.). The realization of this idea requires novel theories, algorithms, tools, and techniques to discover, express, verify, and evolve software intents. Thus, future software systems will be able to verify themselves that they meet their intents. Moreover, they will be able to respond to deviations from intents through selfcorrection. In this article we propose a research agenda, outlining which novel theories, algorithms and tools are required., Software Technology, Programming Languages

Software is widely used, and society increasingly depends on its reliability. However, software has become so complex and it evolves so quickly that we fail to keep it under control. Therefore, we propose intents: fundamental laws that capture a software systems’ intended behavior (resilient, secure, safe, sustainable, etc.). The realization of this idea requires novel theories, algorithms, tools, and techniques to discover, express, verify, and evolve software intents. Thus, future software systems will be able to verify themselves that they meet their intents. Moreover, they will be able to respond to deviations from intents through selfcorrection. In this article we propose a research agenda, outlining which novel theories, algorithms and tools are required., Software Technology, Programming Languages

Real Estate and Housing, Architecture and The Built Environment

Real Estate and Housing, Architecture and The Built Environment