Search

With the development of waste recovery techniques, previous research has revealed that coarse fractions of municipal solid waste incineration (MSWI) bottom ash (BA) after proper treatment could be applied in the construction sector, while the fines are seldom recovered in practice and normally landfilled. This study explores the potential application of fine MSWI BA (0–2 mm) as a supplementary cementitious material (SCM) in Portland cement (PC) mixtures. Mechanical and chemical pre-treatment approaches have been designed with various conditions to optimize the treating process. The chemical and mineralogical compositions, as well as the metallic Al content in BA were characterized before and after the pre-treatment. It was found that both methods are effective in removing the metallic Al content in BA, Moreover, BA derived from mechanical treatment exhibited more contribution to the hydration reaction in PC mixtures, as revealed by the amount of reaction products and mineral phases formed in hardened trial mixtures. BA obtained was further partially blended in PC mortars to evaluate the performance as compared to SCMs and inert fillers. It was found that treated BA resulted in a slight retarding effect on the reaction kinetics. Treated BA behaved better than the coal fly ash to contribute to the strength development, while the inclusion of BA did not lead to significant influences on the workability., Civil Engineering & Geosciences, Materials and Environment, Concrete Structures

The urban energy transition requires innovative heating and cooling systems, as well as enhanced flexibility in electricity usage. This paper explores the theoretical potential for vertical farms to contribute to the energy transition by supplying residual heat to local district heat networks and flexible electricity usage. A stepped approach was used to design energy systems that achieve thermal energy balance through heat and cold exchange between a vertical farm and buildings within a specific Dutch neighbourhood. Furthermore, alternative lighting strategies for vertical farms were explored to reduce grid congestion and to respond to electricity price fluctuations, limiting the mismatch between electricity generation and demand. Compared to the baseline scenario, the energy system with an integrated vertical farm reduces overall energy use by 15 %, even when accounting for the farm's electricity use. By adopting intermittent lighting that is better aligned with electricity price fluctuations, the vertical farm obtained annual cost savings of 14 %. The integration of vertical farms into energy systems can, therefore, contribute to the urban energy transition by producing residual heat to balance thermal energy system and save money for growers by optimising LED operations to align with electricity price fluctuations, whilst producing fresh vegetables for the city., Environmental & Climate Design

Over the past century, the main channel of the Waal has experienced erosion of approx-imately 1-2 metres (Ylla Arb´os et al., 2021; Chowdhury et al., 2023). This erosion leads to various problems such as instability of struc-tures or disruption to shipping. To address this ongoing degradation, a potential solution is the implementation of sediment nourishments. Recent pilot studies have been conducted in 2016 and 2019 to investigate the feasibility of using sediment nourishments in the main channel of the Dutch Rhine (Becker, 2023). Another possibility of nourishing is to add sed-iment to the groyne fields. Under the influence of currents and ship waves, sediment is ex-pected to be transported to the main channel, causing a groyne field to act as a sand mo-tor. To explore this concept, Rijkswaterstaat initiated a pilot project with sediment nourish-ments in three groyne field clusters along the Waal during the fall of 2023. The pilot includes an extensive measurement campaign., Rivers, Ports, Waterways and Dredging Engineering

Climate change is responsible for global shifts in precipitation patterns and an overall in-crease in global temperatures. The transi-tions are anticipated to modify the river hydro-graph and sea level. The changes to the hy-drograph are also likely to influence sediment flux. These alterations imply shifts in both up-stream and downstream boundaries for river bifurcations. However, the resulting bifurca-tion response remains uncertain and warrants further investigation. Our objective is to un-derstand the extent of large-scale and long-term response of river bifurcations to climate change. We take the Upper Dutch Rhine bifur-cation region as our case study and develop a 1D hydro-morphodynamic model representing the system to achieve this goal., Rivers, Ports, Waterways and Dredging Engineering

Channel adjustment in engineered rivers is often associated with channel bed incision (e.g., Chowdhury et al., 2023, Czapiga et al., 2022a, 2022b, Ylla Arbós et al., 2021). Channel bed incision reduces the stability of in-river structures, exposes river-crossing cables and pipelines, and the spatial variability of channel bed incision due to less erodible reaches creates shipping bottlenecks. Various measures have been implemented to cope with these issues. They range from sediment nourishments to erosion control structures (e.g., Habersack and Piégay, 2007). Our objective is to assess the potential of floodplain lowering and sediment nourishments in mitigating large-scale channel bed incision in engineered rivers affected by climate change, considering a spatial scale of hundreds of kilometres. Our domain of interest is the Rhine River between Bonn, Germany, to Gorinchem, Netherlands. This reach has been extensively channelized during the 18th-20th centuries for improved navigation and flood protection (e.g., Ylla Arbós et al., 2021)., Rivers, Ports, Waterways and Dredging Engineering

The dynamics of the bifurcating Karnali river in the western plains of Nepal and India is governed by the geomorphological processes in an alluvial fan. The dynamic branches showcase a notable degree of braiding, dominant channel switching and unequal discharge partitioning. Since recent switching of the dominant channel of Karnali system occurred after an intense monsoon in 2009, the eastern Geruwa branch of the system, which used to be dominant channel passing through the Bardiya National Park, is now receiving a lower share of discharge. This situation exacerbates in the low flow periods when there is very small flow in the Geruwa branch. This decreasing discharge has been associated with depleting diversity of wildlife habitat in Bardiya National Park (Bijlmakers et al., 2023). For sustainable habitat management in the Bardiya National Park, there is a necessity to study the dynamic Karnali river and its two branches, the eastern Geruwa branch and the western Kauriala branch. Activities such as sediment mining, construction of irrigation and hydropower and inter-basin water transfer projects will potentially influence the system dynamics. Our objective is to understand the switching behaviour of the Karnali system to the natural dynamics such as bend sorting (Baar et al., 2020; Parker & Andrews, 1985) of sediments at the location where water from the main Karnali enters the Geruwa branch, and offer understanding of system response to human interventions especially with regards to the distribution of discharge between the Geruwa and Kauriala branches. We combine the technique of field observations and numerical modelling to study the system., Rivers, Ports, Waterways and Dredging Engineering, Civil Engineering & Geosciences, Water Resources

River restoration is an established method for the rehabilitation of river ecosystems in order to combat the current declines of freshwater biodiversity (Wohl et al., 2005; WWF, 2022). The urgency of restoration is recognized internationally, as the IUCN has proclaimed 2021-2030 to be the ‘Decade on Ecosystem Restoration’ (Cooke et al., 2022). So far only few restoration projects have been evaluated based on monitoring data (England et al., 2021), and there is a need for monitoring techniques to assess restoration practices. The analysis of environmental DNA (eDNA) has gained popularity in the last decades, as it allows for rapid standardized biomonitoring across the tree of life, requires a reduced dependence on taxonomic expertise for species identification, and it is cheaper than traditional monitoring methods. Depending on the organism, eDNA is shed by its host in forms such as mucous, shed skin cells, and faeces. After release, eDNA is exposed to a wide spectrum of environmental variables that may impact its state, transport capacity, fate, and the subsequent inference made by the practitioner (Barnes and Turner, 2016). Our objective is to study how eDNA quantities are affected by flow and sediment transport in river ecosystems., Rivers, Ports, Waterways and Dredging Engineering

Erosion-control measures in rivers aim to provide sufficient navigation width, reduce local erosion, or to protect neighboring communities from flooding. These measures are typically devised to solve a local problem. However, local channel modifications trigger a large-scale channel response in the form of migrating bed level and sediment sorting waves. Our objective is to investigate the large-scale channel response to such measures. We consider the lower Rhine River from Bonn (Germany) to Gorinchem (the Netherlands), where numerous erosion-control measures have been implemented since the 1980s. We analyze measured bed level data (1999–2020) around four erosion-control measures, comprising scour filling, bendway weirs, and two fixed beds. To get further insight on the physics behind the observed behavior, we set up an idealized one-dimensional numerical model. Finally, we study how the geometry and spacing of the measures affect channel response. We show that erosion-control measures reduce the sediment flux due to (a) lack of erosion over the measure and (b) sediment trapping upstream of the measure, resulting in downstream-migrating incision waves that travel tens of kilometers at decadal timescales. When the measures are in close proximity, their downstream effects may be amplified. We conclude that, despite fulfilling erosion-control goals at the local scale, erosion-control measures may worsen large-scale channel-bed incision., Rivers, Ports, Waterways and Dredging Engineering

The Dutch energy landscape is becoming more complex due to various interacting factors and uncertainties, creating what are known as "wicked problems" that demand collaborative solutions. This study addresses knowledge gaps by developing a collaborative guide for fostering effective Multi-Stakeholder Collaborations (MSCs) that can endure over time. Through literature reviews and interviews, 69 factors influencing MSC durability were identified and organized using innovative clustering techniques, resulting in the collaborative guide. To test the effectiveness of this guide and develop recommendations to an existing MSC, the guide is applied to the MMvIB project as a case study using a structured four-step approach known as the COOP method. This method involves Consultation, Observation, Organization, and Perpetual development phases. By prioritizing influential factors and adapting to project dynamics, this approach aims to enhance the long-term success of MSCs. The insights and methods derived from this research are relevant to a wide range of collaborative contexts. Future research should focus on refining the approach and developing implementation strategies for these factors., Double degree in Complex Systems Engineering and Management and Applied Physics, MMvIB, Complex Systems Engineering and Management (CoSEM), Applied Physics

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., Air Transport & Operations

This report is concerned with a friendly competition for formal verification and policy synthesis of stochastic models. The main goal of the report is to introduce new benchmarks and their properties within this category and recommend next steps toward next year’s edition of the competition. Given that the tools for stochastic models are at their early stages of development compared to those of non-probabilistic models, the main focus is to report on an initiative to collect a set of minimal benchmarks that all such tools can run, thus facilitating the comparison between the efficiency of the implemented techniques. This friendly competition took place as part of the workshop Applied Verification for Continuous and Hybrid Systems (ARCH) in Summer 2023., Air Transport & Operations

In this paper, we show the mathematical equivalence of two popular modulation schemes: OSDM and OTFS. The former is mainly used in underwater acoustic communications, while the latter scheme is a promising modulation technique in radio-frequency communications. Although literature suggests a link between the two modulation schemes by connecting them to related modulation schemes like V-OFDM and A-OFDM, to the best of the authors’ knowledge, a direct mathematical comparison between the schemes has not been presented yet. The main purpose of this paper is therefore to show the mathematical equivalence of the two schemes. In addition, by combining the knowledge of acoustic and radio-frequency communications, we give insight in the performance of OSDM/OTFS in terms of intersymbol interference (ISI) and intercarrier interference (ICI) by analyzing its signal structure., Electrical Engineering, Mathematics and Computer Science, ESA Education Service Centre, Signal Processing Systems

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., Rivers, Ports, Waterways and Dredging Engineering, Support Hydraulic Engineering, Water Resources

Human intervention makes river channels adjust their slope and bed surface grain size as they transition to a new equilibrium state in response to engineering measures. Climate change alters the river controls through hydrograph changes and sea level rise. We assess how channel response to climate change compares to channel response to human intervention over this century (2000–2100), focusing on a 300-km reach of the Rhine River. We set up a schematized numerical model representative of the current (1990–2020), non-graded state of the river, and subject it to scenarios for the hydrograph, sediment flux, and sea level rise. We conclude that the lower Rhine River will continue to adjust to past channelization measures in 2100 through channel bed incision. This response slows down as the river approaches its new equilibrium state. Channel response to climate change is dominated by hydrograph changes, which increasingly enhance incision, rather than sea level rise., Rivers, Ports, Waterways and Dredging Engineering

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., Rivers, Ports, Waterways and Dredging Engineering

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., Rivers, Ports, Waterways and Dredging Engineering

The pressure trigger (PT) algorithm of the SLE 6000 ventilator is a non-invasive respiratory rate (RR) monitoring technique that can detect spontaneous breathing during non-invasive respiratory support. The PT algorithm can detect spontaneous breaths based on air pressure changes in the ventilatory circuit, labelling the pressure fluctuation as a PT. The threshold for the algorithm to detect a PT is set by the trigger sensitivity (TS), a user-set variable ranging between 0-100%. Although regularly used in the neonatal intensive care (NICU) of the Leiden University Medical Centre (LUMC), the PT algorithm still needs to be clinically validated as its performance in spontaneous breath detection is still unknown. To investigate the accuracy of the PT algorithm, it is necessary to collect timestamps of detected PTs, but these are not yet accessible. The aim of this study was to design and validate an extraction method to obtain the PT timestamps. For this, an experimental setup (EXP-SET) was designed, which connects to the ventilatory circuit of the SLE 6000 and allows us to perform to acquire the necessary timestamps. A replicated version of the PT algorithm detects PT timestamps from the raw pressure data acquired from the EXP-SET. To validate the similarity in PT detection between the EXP-SET and the SLE 6000, standardized and unstandardized bench tests were performed. The SLE 6000 was assumed to be the golden standard in PT detection during the bench tests. In the standardized bench test, the EXP-SET showed a sensitivity between 0.952 - 1.0 and a positive predictive value (PPV) between 0.997 - 1.0 for 50% TS. However, when increasing TS to 100%, the EXP-SET’s sensitivity and PPV decreased to 0.466- 0.618 and 0.673 - 0.844. In the unstandardized bench test, the sensitivities and PPVs were 0.794 and 1 for 50% TS, 0.901 and 0.996 for 75% TS and 0.785 and 0.958 for 100% TS. The results show that the designed EXP-SET does not yet detect PTs identically to the SLE 6000. Th, Technical Medicine

Vertical farms use some resources very efficiently. However, their electricity use is considerable, and a significant amount of waste heat is produced. This paper investigates how the integration of vertical farms in buildings could reduce the use of energy, water, and nutrients collectively across both entities by leveraging potential resource synergies. The paper considered the integration of vertical farms in apartments, offices, restaurants, swimming pools, and supermarkets located in the Netherlands. For each typology, the floor area heated and the amount of building users fed by one m2 of one production layer within the vertical farm was calculated, along with required outputs of water and nutrients from the building to sustain the vertical farm. The energy savings of different integration strategies were calculated for each building typology in comparison to a non-integrated approach. Results showed that the synergetic integration of vertical farms with buildings reduced the year-round energy use of the climate systems of both entities collectively by between 12 and 51%. The integration of vertical farms with buildings decreases the use of energy, water, and nutrients from external sources and offers great potentials to reduce the environmental impacts of both entities, whilst producing food in urban environments., Environmental & Climate Design

This thesis uses a clever (re)labeling method, significantly improving the dataset's quality. However, it turned out that the dataset still has its limitations. A large portion of false positives are caused by labeling errors. After comparing several machine learning models, it follows that a 9-layer ResNET model is optimal. Adding more layers will not result in better performance. Unexpectedly, initializing ResNET with pre-trained weights actually decreases performance. In addition, the effect of oversampling and/or using a weighted binary cross-entropy loss is investigated. Just oversampling leads to overfitting, but using a weighted binary cross-entropy loss isn't ideal either. The best performance is achieved by combining weighted binary cross-entropy loss with oversampling. Decision threshold optimization substantially improved the results. The experiments allowed for selecting the ideal configuration, which substantially increased performance. The best-performing configuration achieved a strong co, Applied Mathematics

A bifurcation in an engineered river system (i.e., fixed planform and width) has fewer degrees of freedom in its response to interventions and natural changes than a natural bifurcation system. Our objective is to provide insight into how a bifurcation in an engineered river responds to peak flows and human interventions. To this end, we analyze the change in hydraulics, bed level, and bed surface grain size in the region of two bifurcations in the upper Rhine delta in the Netherlands over the last century. We show that, over the last two decades, the water discharge in one bifurcate (the Waal branch) has steadily increased at the expense of the other. This gradual increase in the water discharge of the first branch is associated with its erosion rate being larger than the other branch. The quick succession of two or three peak flow events (1993, 1995, and 1998) caused rapid sediment deposition over the upstream part of the bifurcate that has gradually lost discharge, which seems to have triggered the slow change in flow partitioning., Rivers, Ports, Waterways and Dredging Engineering

The increasing use of on-board sensor monitoring and data-driven algorithms has stimulated the recent shift to data-driven predictive maintenance for aircraft. This paper discusses emerging challenges for data-driven predictive aircraft maintenance. We identify new hazards associated with the introduction of data-driven technologies into aircraft maintenance using a structured brainstorming conducted with a panel of maintenance experts. This brainstorming is facilitated by a prior modeling of the aircraft maintenance process as an agent-based model. As a result, we identify 20 hazards associated with data-driven predictive aircraft maintenance. We validate these hazards in the context of maintenance-related aircraft incidents that occurred between 2008 and 2013. Based on our findings, the main challenges identified for data-driven predictive maintenance are: (i) improving the reliability of the condition monitoring systems and diagnostics/prognostics algorithms, (ii) ensuring timely and accurate communication between the agents, and (iii) building the stakeholders’ trust in the new data-driven technologies., Air Transport & Operations

Nanostructured metal hydrides could play a key role in a hydrogen economy. The nanostructuring or confinement of these materials as, e.g., thin films significantly affects the structural and functional properties. For tantalum hydride, a versatile hydrogen sensing material, we show that the confinement of tantalum as a thin film extends the solubility limit by suppressing the phase transition observed in bulk upon hydrogenation. Different from bulk, the body centered cubic unit cell continuously deforms with unequal lattice constants and angles between lattice vectors. This deformation ensures that the volumetric expansion is realized in the out-of-plane direction, and surprisingly, completely elastic in nature. The first-order phase transition suppression combined with the continuous elastic deformation of the tantalum unit cell over an extraordinary wide solubility range ensures the superb performance of tantalum and its alloys as a hysteresis-free optical hydrogen sensing range over a hydrogen pressure/concentration range of over 7 orders of magnitude., RID/TS/Instrumenten groep, ChemE/O&O groep

The tandem PV technology can potentially increase the efficiency of PV modules over 30%. To design efficient modules, a quantification of the different losses is important. Herein, a model for quantifying the energy loss mechanisms in PV systems under real-world operating conditions with a level of detail back to the components and their fundamental properties is presented. Totally, 17 losses are defined and divided into four categories (fundamental, optical, electrical, and system losses). As example, a system based on a > 29% two-terminal perovskite/silicon tandem cell is considered. The loss distribution at standard test conditions is compared to four geographical locations. The results show that the thermalization, reflection, and inverter losses increase by 1.2%, 1.1%, and 1.4%, respectively, when operating outdoors. Additionally, it is quantified how fill factor gains partly compensate the current mismatch losses. For example, a mismatch of 7.0% in photocurrent leads to a power mismatch of 1.2%. Therefore, the power mismatch should be used as indicator for mismatch losses instead of a current mismatch. Finally, herein, it is shown that solar tracking increases not only the in-plane irradiance but also the efficiency of the tandem module., Photovoltaic Materials and Devices, Electrical Sustainable Energy

For diffusions, a well-developed approach in rare event estimation is to introduce a suitable factorization of the reach probability and then to estimate these factors through simulation of an Interacting Particle System (IPS). This paper studies IPS based reach probability estimation for General Stochastic Hybrid Systems (GSHS). The continuous-time executions of a GSHS evolve in a hybrid state space under influence of combinations of diffusions, spontaneous jumps and forced jumps. In applying IPS to a GSHS, simulation of the GSHS execution plays a central role. From literature, two basic approaches in simulating GSHS execution are known. One approach is direct simulation of a GSHS execution. An alternative is to first transform the spontaneous jumps of a GSHS to forced transitions, and then to simulate executions of this transformed version. This paper will show that the latter transformation yields an extra Markov state component that should be treated as being unobservable for the IPS process. To formally make this state component unobservable for IPS, this paper also develops an enriched GSHS transformation prior to transforming spontaneous jumps to forced jumps. The expected improvements in IPS reach probability estimation are also illustrated through simulation results for a simple GSHS example., Air Transport & Operations

Climate change puts pressure on river systems, as it increasingly alters the river controls. Engineered rivers with a fixed planform respond to climate change and human intervention by adjusting the channel slope and bed surface grain size distribution. This response often consists of channel bed incision, over hundreds of kilometres, and during decades to centuries, resulting in serious disruptions of inland navigation, increased flood risk, and ecological degradation. Here we investigate how the lower Rhine River (Bonn, Germany – Vuren, the Netherlands, including the Pannerden bifurcation) continues to adjust to channelization measures of the 19th century (Ylla Arbós et al., 2021), and responds to different climate scenarios of control change over the 21st century, using a schematized one-dimensional numerical model for mixed size sediment., 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., Rivers, Ports, Waterways and Dredging Engineering

Typically the time scale of river response to change of the controls (i.e., flow duration curve, sediment flux, and sea level) is of the order of decades to centuries. Understanding temporal change and, in particular, abrupt change in channel response is increasingly important in engineered river systems, as abrupt change may negatively affect flood risk, navigation, and freshwater supply. The analysis of abrupt change in engineered systems with a bifurcation (i.e., a single channel splitting into two branches or bifurcates) is complicated by the fact that insight and measured data on the partitioning of water and sediment over the bifurcates are typically lacking. Our objective is to provide insight on whether observed abrupt change of the Pannerden bifurcation in the upper Rhine delta (Netherlands) may be associated with tipping., 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., Rivers, Ports, Waterways and Dredging Engineering

Rivers flowing from the highlands to the lowlands, characterize the Terai Arc Landscape (TAL) in Nepal and India, but also the neighbouring region in Bhutan. The sudden change in slope results in deposition of nutrient-rich sediment, which forms large alluvial or fluvial fans that enhance biodiversity and economic activities in the region. Our objective is to identify similarities and differences in hydro-morphodynamics between the TAL rivers, with a focus on the Karnali and Koshi systems in Nepal. It is expected that such insight in river dynamics will aid the sustainability and management of the TAL rivers. To this end, we investigate and compare discharge characteristics, historical flow paths, and morphodynamic characteristics such as channel shifting, braiding, and flow partitioning to identify and understand the fan scale dynamics of the two systems. Hereto we used optical remote sensing images and river discharge time series from Chisapani (Karnali) and Chatara (Koshi) gauging stations. In addition, we conducted a field campaign in November 2022., 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., Rivers, Ports, Waterways and Dredging Engineering, Support Hydraulic Engineering, Water Resources

A monitoring technique capable of assessing the status of an aquatic ecosystem is needed for reversing negative trends in river biodiversity. Recently, an innovative technique for detecting the degree of biodiversity based on environmental DNA traces (mucus, shed skins etc.) has been proposed (Carraro et al., 2020). This eDNA-based biomonitoring relies on the collection and processing of water samples containing genetic material released by organisms. In recent years, the research community has made significant efforts to advance the identification of species from biological samples, for instance by expanding genetic reference databases. However, eDNA technique implementation is hampered by a lack of knowledge about the dynamics of biological traces in rivers. Here, the aim is to investigate the transport of eDNA in water streams, while considering processes such as degradation and spreading., 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., Rivers, Ports, Waterways and Dredging Engineering

River bifurcations divide the water and sediment over two downstream branches or bifurcates. As the changing climate adjusts the boundary conditions (i.e., base level, hydrograph, and sediment flux) for bifurcations, it will affect their flow and sediment partitioning over the bifurcates. Our objective is to provide insight into the response of a bifurcation to sea level rise (SLR). To this end, we compare the response of an idealized bifurcation in an engineered river (i.e., with a fixed planform and width) to SLR to the one of a single channel, using a one-dimensional numerical model system., 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., Rivers, Ports, Waterways and Dredging Engineering

Sanitary Engineering, Water Resources, Rivers, Ports, Waterways and Dredging Engineering

Rivers, Ports, Waterways and Dredging Engineering

Rivers, Ports, Waterways and Dredging Engineering

Rivers, Ports, Waterways and Dredging Engineering

Rivers, Ports, Waterways and Dredging Engineering, Environmental Fluid Mechanics

Rivers, Ports, Waterways and Dredging Engineering

Accurate yet computationally efficient modelling of fixed-wing airborne wind energy systems is key in the preliminary design phase. For the simulation framework of large scale fixed-wing airborne wind energy systems an FSI model is developed that can evaluate flight states in the order of seconds and is able to account for viscosity and multi-element airfoils. MSES is combined with a lifting line for the aerodynamic calculations and the stiffness matrix from a finite element method is used to calculate the deformations. A circular flight path is used as a validation case for the developed model, for which data is available from a panel method and CFD. The developed model shows significant improvements from the panel method and evaluates the flight states in the order of seconds. Therefore, the new model can be used for further research and development of fixed-wing AWESs., Aerospace Engineering

This paper focuses on estimating reach probability of a closed unsafe set by a stochastic process. A well-developed approach is to make use of multi-level MC simulation, which consists of encapsulating the unsafe set by a sequence of increasing closed sets and conducting a sequence of MC simulations to estimate the reach probability of each inner set from the previous set. An essential step is to copy (split) particles that have reached the next level (inner set) prior to conducting a MC simulation to the next level. The aim of this paper is to prove that the variance of the multi-level MC estimated reach probability under fixed assignment splitting is smaller or equal than under random assignment splitting methods. The approaches are illustrated for a geometric Brownian motion example., Aerospace Transport & Operations

De Nederlandse woningmarkt is slecht toegankelijk, creëert vermogensongelijkheid en is grillig. Dat laatste is schadelijk voor onze economie. Bovendien is het huidige woonbeleid duur. Een grondige renovatie van het woonbeleid biedt een structurele oplossing., Real Estate Management

Engineering modifications of rivers, e.g., dams or groynes, often induce long-term riverbed erosion, which can be mitigated with sediment nourishments. Here, we consider nourishments to mitigate channel bed erosion induced by channel narrowing, as opposed to the more common application downstream of dams. Our objective is to assess and quantify how dumping location, grainsize, and volume are important for mitigation efficacy. Our results show that erosion can be mitigated if nourishments change the sediment flux such that the corresponding equilibrium channel slope is increased. This is achieved by coarsening the sediment flux throughout the reach, increasing magnitude of the sediment flux, or both. Flux is coarsened via additions of sediment at or coarser than the bed surface and nourished sediment should be distributed throughout the incising reach. The second option is nourishing a large volume of relatively fine sediment to increase the equilibrium channel slope. Additions of fine sediment in small volumes decrease the equilibrium channel slope and enhance erosion, because the fine sediment flux makes the gravel more mobile., 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., Rivers, Ports, Waterways and Dredging Engineering

CD4+CD25+FOXP3+ regulatory T (Treg) cells control immunological tolerance. Treg cells are generated in the thymus (tTreg) or in the periphery. Their superior lineage fidelity makes tTregs the preferred cell type for adoptive cell therapy (ACT). How human tTreg cells develop is incompletely understood. By combining single-cell transcriptomics and flow cytometry, we in this study delineated three major Treg developmental stages in the human thymus. At the first stage, which we propose to name pre-Treg I, cells still express lineage-inappropriate genes and exhibit signs of TCR signaling, presumably reflecting recognition of self-antigen. The subsequent pre-Treg II stage is marked by the sharp appearance of transcription factor FOXO1 and features induction of KLF2 and CCR7, in apparent preparation for thymic exit. The pre-Treg II stage can further be refined based on the sequential acquisition of surface markers CD31 and GPA33. The expression of CD45RA, finally, completes the phenotype also found on mature recent thymic emigrant Treg cells. Remarkably, the thymus contains a substantial fraction of recirculating mature effector Treg cells, distinguishable by expression of inflammatory chemokine receptors and absence of CCR7. The developmental origin of these cells is unclear and warrants caution when using thymic tissue as a source of stable cells for ACT. We show that cells in the major developmental stages can be distinguished using the surface markers CD1a, CD27, CCR7, and CD39, allowing for their viable isolation. These insights help identify fully mature tTreg cells for ACT and can serve as a basis for further mechanistic studies into tTreg development., 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., Pattern Recognition and Bioinformatics

Sediment transport capacity and supply of sediment to a river channel increase significantly during peak flow events. Here we study how a river bifurcation system (partitioning water and sediment over its downstream branches) responds to peak flow events. We focus on the Pannerdense Kop bifurcation in the Dutch Rhine River, an engineered system where planform and channel width are fixed. We analyze water discharge and bed level data measured over the last century. We observe rapid aggradation in one of the branches (Pannerden Channel) following the peak flow events of 1993 and 1995, and little to no bed level change in the other branch (Waal). Prior to the event, both branches eroded, and the upstream part of the Pannerden Channel had a greater erosion rate than the Waal. After the 1993 and 1995 peak flow events, the erosion in the upstream part of the Pannerden Channel slowed significantly, whereas the upstream part of the Waal branch continued to erode (though at a smaller pace than before the peak flow events). This differential erosion has resulted in a gradual increase of water discharge toward the Waal branch. Interestingly, the bifurcation system does not appear to respond equally to all peak flow events. We hypothesize that the bifurcation response to the 1993 and 1995 peak flows differs from previous peak flows because of the sequence of the two events. Between the 1993 and 1995 events, the system may not have had sufficient time to disperse the sediment deposited at the upstream end of the Pannerden channel. Another reason for the response to the 1993 and 1995 peak flows to differ from previous events may be that the channel bed surface within the region of interest has coarsened significantly. This study illustrates the importance of peak flows regarding bifurcation dynamics, and further research is focused on the interaction between bifurcation dynamics and the dynamics of the larger-scale system., 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., Rivers, Ports, Waterways and Dredging Engineering

Carbon Capture and Storage (CCS) is considered an essential solution to reaching climate goals. The two main identified transport modes in CCS, pipelines and ships, are widely compared to each other in the literature. This research contributes to the literature about the evaluation of transportation modes in CCS chains, by determining to what extent electrified ships can play a role in CCS. This is not studied before. This research is executed by following the Systems Engineering approach, in particular the SIMIE process. In a proposed point-to-point network for onshore transportation, mainly general diesel-propelled barges would perform with the lowest costs per ton, whereby the distance ranges from 25 km up to 250 km. As longer the distances, more Tank-to-Wheel (TTW) emissions savings could be obtained if barge transport is electrified. Identifying the most accurate emissions reporting method and performing operational validation for modelling the transport modes and trajectories could provide the obtained results with more scientific and practical robustness., Transport, Infrastructure and Logistics

To complete the energy transition, a high efficiency for photovoltaic (PV) modules is desirable to reduce the needed material and surface area (per unit of generated electrical energy). The tandem PV technology has the potential to increase the efficiency of PV modules over 30%. In order to design efficient solar cells, a quantification of the different losses is important. Moreover, research in the losses of PV system has resulted in important insights for PV technology. This work introduces a comprehensive model for quantifying the different loss mechanisms in a PV system with tandem cells. The loss analysis model will be added to the PVMD Toolbox, which is a software developed at Photovoltaic Materials and Devices group at Delft University of Technology. This software can be used to simulate the energy yield of a PV system at any given location. In the loss analysis model, 17 losses are defined and divided into four categories (fundamental, optical, electrical and system losses). The developed model will be used to analyse the loss distribution under different operating conditions for four different PV modules. These different modules are a mono-facial crystalline silicon, a bifacial crystalline silicon, a two-terminal perovskite/silicon tandem, and a three-terminal perovskite/silicon tandem module. The design of these modules is based on a >29% efficient perovskite/silicon tandem cell, fabricated by HZB. The loss distribution of every module is simulated for Standard Test Conditions (STC) and for real word conditions at four geographical locations. Generally, we find that modules operating in tropical high irradiance climates have the lowest efficiency. For all locations, the difference in losses compared to STC follow similar trends. When the two-terminal perovskite/silicon module is simulated at STC, the loss distribution of the fundamental, optical, electrical, and system losses are 54.8%, 8.9%, 8.5%, and 0.1%, leaving a DC module efficienc, Electrical Engineering | Sustainable Energy Technology

This paper reports on a pilot project focused on the use of the formative assessment resource Make Design Learning Visible (MDLV) in different national settings. The MDLV resource centers on a design model involving seven interactive design skills and a formative assessment model involving five strategies. A team of researchers from seven countries in three continents, are working collaboratively with a teacher practitioner from each country to develop the structure of the research project and trial of a design activity that utilises the MDLV skills and approach to formative assessment. This paper reports on ongoing exploratory early work with the teacher practitioners trialing a short design project with an overarching theme of sustainability, a focus on developing two design skills (Empathy and Sharing ideas) and two formative assessment strategies (‘Activating learners as resources for one another’ and ‘Activating learners as owners of their learning’). The project centers on a design brief customised for each national setting and relevant for learners aged between 10 and 15 years of age. A structured portfolio supporting an iterative design process forms the basis of tangible evidence of learner responses. The pilot is providing insights into the effectiveness of the MDLV resource in developing design skills and formative assessment across national settings. Additionally, the pilot contributes understandings of comparative participatory research involving teacher practitioners across countries. The exploratory nature of the early stages of the project intentionally allows some aspects to be customised locally by teachers as we seek to understand rather than dictate how the resource is best used in the local educational contexts. To this end, the overarching structure and pedagogy of the activity is fixed, but aspects such as lesson timings, choices around the use of MDLV tools and the further MDLV design skills are flexible., Science Education and Communication

This report presents the results of a friendly competition for formal verification and policy synthesis of stochastic models. It also introduces new benchmarks and their properties within this category and recommends next steps for this category towards next year’s edition of the competition. In comparison with tools on non-probabilistic models, the tools for stochastic models are at the early stages of development that do not allow full competition on a standard set of benchmarks. We report on an initiative to collect a set of minimal benchmarks that all such tools can run, thus facilitating the comparison between efficiency of the implemented techniques. The friendly competition took place as part of the workshop Applied Verification for Continuous and Hybrid Systems (ARCH) in Summer 2022., Air Transport & Operations

The Waal Branch of the Rhine River has eroded over the last 150 years following channel straightening and narrowing. In 2014–2015 a pilot project replaced existing groynes over an 11 km long reach with three longitudinal training walls (LTWs) to mitigate channel bed erosion, among other purposes. Walls are lower than the river bank and split the flow between a primary and an auxiliary channel, which are hydraulically connected during floods. Water enters the auxiliary channel at three elevations (from bottom to top): via an entrance weir, through inter-wall notches, and over the wall. Bathymetry and discharge data were collected for 5 years after construction, which is a first indication that longitudinal dams can help mitigate channel bed erosion and analyzed to understand how the walls partition water and sediment and whether erosion is mitigated by LTWs. As the river discharge increases, a larger fraction of flow is diverted from the primary channel into the auxiliary channel. After a flood, sediment is deposited in the primary channel near the upstream end of each wall and localized scour occurs where the auxiliary channel rejoins the primary channel. Between floods, the accumulated sediment disperses and scour pits tend to fill. We observe a net-accumulation of sediment in the study domain 5 years after construction. Erosion is best mitigated when weir flow is minimized to keep bed material in the primary channel, but weir flow remains important at lower flows for ecological purposes., Rivers, Ports, Waterways and Dredging Engineering

UAS-based commercial services such as urban parcel delivery are expected to grow in the upcoming years and may lead to a large volume of UAS operations in urban areas. These flights may pose safety risks to persons and property on the ground, which are referred to as third-party risks. Path-planning methods have been developed to generate a nominal flight path for each UAS flight that poses relative low third-party risks by passing over less risky areas, e.g., areas with low-density unsheltered populations. However, it is not clear if risk minimization per flight works well in a commercial UAS operation that involves a large number of annual flights in an urban area. Recently, it has been shown that when using shortest flight path planning, a UAS-based parcel delivery service in an urban area can lead to society-critical third-party risk levels. The aim of this paper is to evaluate the mitigating effect of state-of-the-art risk-aware path planning on these society-critical third-party risk levels. To accomplish this, a third-party risk simulation using the shortest paths is extended with a state-of-the-art risk-aware path-planning method, and the societal effects on third-party risk levels have been assessed and compared to those obtained using shortest paths. The results show that state-of-the-art risk-aware path planning can reduce the total number of fatalities in an area, but at the cost of a critical increase in safety risks for persons living in areas that are favored by a state-of-the-art risk-aware path-planning method., Air Transport & Operations

Over the past decades, various farming methods have evolved in response to the global challenges of increasing food demands, decreasing availability of arable land, and climate change. One of these new farming methods is vertical farming. To understand the contribution of vertical farms to future sustainable food production, beyond its efficient land-use and high yields, this paper evaluates the current carbon footprint of lettuce produced in an operational vertical farm in comparison to conventional open-field farming and both soil-based and hydroponic greenhouse cultivation in the Netherlands. The assessment includes the greenhouse gas emissions of the life cycle of the farm and the crop, from cradle-to-grave. An alternative scenario is explored to include the lost carbon sequestration potential by land-use change, identical packaging for all farming methods, and renewable energy usage. The carbon footprint of the vertical farm was 5.6–16.7 times greater than that of the conventional farming methods in the baseline scenario and 2.3 to 3.3 times in the alternative scenario. The electricity demands of the vertical farm represented 85% of the carbon footprint in the baseline scenario and 66% in the alternative scenario, suggesting that a significant reduction in electricity use is required to compete with conventional farming methods from a carbon footprint perspective. If this could be achieved, vertical farming could become a valid component of future sustainable and food secure systems by its efficient use of land, high yields, minimal use of water, nutrients, pesticides and herbicides, and the ability to be located within or adjacent to cities., Climate Design and Sustainability

We introduce a novel simulation tool capable of calculating the energy yield of a PV system based on its fundamental material properties and using self-consistent models. Thus, our simulation model can operate without measurements of a PV device. It combines wave and ray optics and a dedicated semiconductor simulation to model the optoelectronic PV device properties resulting in the IV-curve. The system surroundings are described via spectrally resolved ray tracing resulting in a cell resolved irradiance distribution, and via the fluid dynamics-based thermal model, in the individual cell temperatures. A lumped-element model is used to calculate the IV-curves of each solar cell for every hour of the year. These are combined factoring in the interconnection to obtain the PV module IV-curves, which connect to the inverter for calculating the AC energy yield. In our case study, we compare two types of 2 terminal perovskite/silicon tandem modules with STC PV module efficiencies of 27.7% and 28.6% with a reference c-Si module with STC PV module efficiency of 20.9%. In four different climates, we show that tandem PV modules operate at 1–1.9 °C lower yearly irradiance weighted average temperatures compared to c-Si. We find that the effect of current mismatch is significantly overestimated in pure optical studies, as they do not account for fill factor gains. The specific yields in kWh/kWp of the tandem PV systems are between −2.7% and +0.4% compared to the reference c-Si system in all four simulated climates. Thus, we find that the lab performance of the simulated tandem PV system translates from the laboratory to outdoors comparable to c-Si systems., Photovoltaic Materials and Devices, Energie and Industrie, Electrical Sustainable Energy

De Nederlandse woningmarkt is slecht toegankelijk, creëert vermogensongelijkheid en is grillig. Dat laatste is schadelijk voor onze economie. Bovendien is het huidige woonbeleid duur. Een grondige renovatie van het woonbeleid biedt een structurele oplossing., Real Estate Management