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Dynamics of Micro and Nano Systems

Overtopping plumes from wave impact is relevant to coastal defence for overtopping analysis of sea walls, levees, and gates. Improved insight into this phenomenon will further enhance the prediction of wave overtopping and its induced hazard, e.g., erosion, saltwater ingress, and a hindrance to traffic. A series of small-scale experiments have been carried out in the WaterLab at TU Delft to characterize the droplets formed by wave impacts. Focused waves were generated by the piston-type wavemaker to control the wave breaking point on the wall, which allowed the creation of different types of wave impact. Impacts were investigated respectively: non-breaking, flip-through, and air pocket. After the wave impact, all the stages of the plume formation were filmed using a high-speed camera at a frame rate of 500fps. In this study, the spray sheet breakup and droplet formation are investigated. A simple approach to estimate the maximum spray height is proposed, which can be used for the splash type overtopping in the future., 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

In marine environment, floating photovoltaic (FPV) plants are subjected to wind, wave and current loadings. Waves are the primary source of fatigue damage for FPVs. The climate change may accumulatively affect the wave conditions, which may result in the overestimation or underestimation of fatigue damage. This paper aims to present a projection method to evaluate the climate change impact on fatigue damage of offshore FPVs in the future. Firstly, climate scenarios are selected to project the global radiative forcing level over decadal or century time scales. Secondly, global climate models are coupled to wind driven wave models to project the long-term sea states in the future. At last, fatigue assessment is conducted to evaluate the impact of climate change on fatigue damage of FPVs. A case study is demonstrated in the North Sea. A global-local method of fatigue calculation is utilized to calculate the annual fatigue damage on the FPVs’ joints. The conclusions indicate that there are decreasing trends of significant wave height and annual fatigue damage in the North Sea with the high emission of greenhouse gases. The fatigue design of FPVs based on the current wave scatter diagrams may be conservative in the future. The manufacture cost of FPVs can be reduced to some extent, which is beneficial to the FPV manufacturers., Offshore and Dredging Engineering

Marine biofouling is a major concern in the operational performance of submerged floating tunnels (SFTs). The objective of this research is to investigate the effects of marine fouling (represented by surface roughness) on the hydrodynamic behavior of SFTs, including the hydrodynamic forces on the SFT subject to current-only, wave-only, and combined current-wave flow conditions. The effects of increased surface roughness induced by marine fouling on the dynamic response of an SFT are characterized by hydrodynamic force coefficients, including drag and inertia coefficients. At the Water Lab of Delft University of Technology (TU Delft), experiments have been performed in a wave-current flume to compare the SFTs’ behaviors as affected by different roughness characteristics. In addition, a parametric cross-section for an SFT is presented, and the hydrodynamic performance associated with surface roughness effects on the parametric shape and circular SFT cross-section shape are compared. The results show that the parametric shape can effectively reduce the drag coefficient (Cd) under current-only conditions and lower the inertia coefficient (Cm) when waves are present. As roughness height and coverage ratio increase, Cd generally increases while Cm decreases. However, small differences in Cd and Cm can be observed with regard to roughness parameters for wave-only conditions. The Morison coefficients adapted for a marine-fouled SFT measured in the experiments are compared to predictions from engineering standards and are recommended for engineering practice., Rivers, Ports, Waterways and Dredging Engineering, Environmental Fluid Mechanics, Hydraulic Structures and Flood Risk

A common task in quality control is to determine a control limit for a product at the time of release that incorporates its risk of degradation over time. Such a limit for a given quality measurement will be based on empirical stability data, the intended shelf life of the product and the stability specification. The task is particularly important when the registered specifications for release and stability are equal. We discuss two relevant formulations and their implementations in both a frequentist and Bayesian framework. The first ensures that the risk of a batch failing the specification is comparable at release and at the end of shelf life. The second is to screen out batches at release time that are at high risk of failing the stability specification at the end of their shelf life. Although the second formulation seems more natural from a quality assurance perspective, it usually renders a control limit that is too stringent. In this paper we provide theoretical insight in this phenomenon, and introduce a heat-map visualisation that may help practitioners to assess the feasibility of implementing a limit under the second formulation. We also suggest a solution when infeasible. In addition, the current industrial benchmark is reviewed and contrasted to the two formulations. Computational algorithms for both formulations are laid out in detail, and illustrated on a dataset., 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., Statistics

Levitation offers extreme isolation of mechanical systems from their environment, while enabling unconstrained high-precision translation and rotation of objects. Diamagnetic levitation is one of the most attractive levitation schemes because it allows stable levitation at room temperature without the need for a continuous power supply. However, dissipation by eddy currents in conventional diamagnetic materials significantly limits the application potential of diamagnetically levitating systems. Here, a route toward high-Q macroscopic levitating resonators by substantially reducing eddy current damping using graphite particle based diamagnetic composites is presented. Resonators that feature quality factors Q above 450 000 and vibration lifetimes beyond one hour are demonstrated, while levitating above permanent magnets in high vacuum at room temperature. The composite resonators have a Q that is >400 times higher than that of diamagnetic graphite plates. By tuning the composite particle size and density, the dissipation reduction mechanism is investigated, and the Q of the levitating resonators is enhanced. Since their estimated acceleration noise is as low as some of the best superconducting levitating accelerometers at cryogenic temperatures, the high Q and large mass of the presented composite resonators positions them as one of the most promising technologies for next generation ultra-sensitive room temperature accelerometers., Dynamics of Micro and Nano Systems, Aerospace Manufacturing Technologies, QN/Steeneken Lab

Mechanical metamaterials are advanced engineering materials that exhibit unusual properties that cannot be found in nature. The elastic properties (i.e., elastic modulus and Poisson's ratio) of mechanical metamaterials can be tuned by changing the geometry of their fundamental unit cells. This allows for the design of metamaterial lattices with targeted quasi-static properties. However, it is not clear how these freedoms contribute to the dynamic properties of mechanical metamaterials. We, therefore, used experimental modal analysis, numerical simulations, and analytical models to study the dynamic response of meta-structures with different values of the Poisson's ratio. We show that Poisson's ratio strongly affects the damping properties of the considered mechanical metamaterials. In particular, we found an inverse relationship between the damping ratio and the absolute value of the Poisson's ratio of the meta-structures. Our results suggest that architected meta-structures similar to those studied could be tailor-made to improve the dissipative performance of mechanical systems. Geometrical design could play an important role in this regard by providing the possibility to tune the various types of quasi-static and dynamic properties of such mechanical metamaterials., Dynamics of Micro and Nano Systems, Biomaterials & Tissue Biomechanics

A jet pump is used to transport a variety of working media and is especially suitable for dredged soil transporting. In this study, a three-dimensional numerical study of a jet pump that is used for slurry delivery was carried out. The characteristics of the internal flow field of the mixing chamber with different working parameters were comprehensively analyzed. The results indicate that the pressure of the axial line decreases with increasing flow ratio (ratio of suction flux and inlet flux) while the pressure of the injected slurry shows a downward trend. With the increase in the flow ratio, the pressure ratio (difference between inlet pressure and suction pressure divided by the difference between exit pressure and suction pressure) falls off while the efficiency presents a parabolic distribution. The pressure ratio can be promoted by properly increasing the length of the mixing chamber so that the available efficiency is broadened. When the mixing chamber length is L = 2.5Dn~4.0Dn (Dn is nozzle outlet diameter), the highly efficient area is wide; in particular, when L = 3.5Dn, the jet slurry pump with the highest efficiency of 27.6% has the best performance., Offshore and Dredging Engineering

This paper presents a new 2D water transport model considering capillary suction to predict the water content evolution in the concrete porosity. The basic formulations of the model are illustrated, and a switching algorithm is introduced to simulated wet-drying effects. Two specific absorption tests are studied to validate this model. The first test conducted under room temperature allows to observe that capillary effects play an important role in the concrete material sorptivity and this phenomenon was well captured by the numerical model. The second test conducted under different temperatures highlight that temperature has significant effect on the capillary suction process and it has been considered in the model as an important input parameter.

Diamagnetic levitation offers stable confinement of an object from its environment at zero power, and thus is a promising technique for developing next generation unclamped resonant sensors. In this work, we realize a resonant weighing scale using a graphite plate that is diamagnetically levitating over a checkerboard arrangement of permanent magnets. We characterize the bending vibrations of the levitating object using laser Doppler vibrometry and use microgram glass beads to calibrate the responsivity of the sensor's resonance frequency to mass changes. The sensor is used for real-time measurement of the evaporation rate of nano-litre droplets with high-accuracy. By analyzing the resonator's frequency stability, we show that the millimeter graphite sensor can reach mass resolutions down to 4.0 ng, relevant to biological and chemical sensing concepts., Dynamics of Micro and Nano Systems, QN/Steeneken Lab

A 3D dynamic numerical model is established for modelling the excavation process for dredging purposes. The interaction between the solid and fluid phases is realized by a specially designed DEM-FVM coupling mechanism, where the fluid-particle interaction forces, the volume fraction information and the particle information are constantly updated and exchanged. Dry and underwater sand cutting simulations are conducted and validated against experimental results. Simulation results of cutting of cohesive soil in atmospheric condition match with the experimental data within acceptable error margin, while the underwater cutting simulations of cohesive soil have not been validated due to the lack of experimental data. Besides, the general applicability of using Discrete Element Modelling (DEM) to create rock samples, and the calibration of DEM rock samples have been investigated, which are essential for conducting atmospheric and underwater rock cutting simulations in the future., Offshore and Dredging Engineering

Mechanical metamaterials are advanced engineering materials that exhibit unusual properties that cannot be found in nature. The elastic properties (i.e., elastic modulus and Poisson's ratio) of mechanical metamaterials can be tuned by changing the geometry of their fundamental unit cells. This allows for the design of metamaterial lattices with targeted quasi-static properties. However, it is not clear how these freedoms contribute to the dynamic properties of mechanical metamaterials. We, therefore, used experimental modal analysis, numerical simulations, and analytical models to study the dynamic response of meta-structures with different values of the Poisson's ratio. We show that Poisson's ratio strongly affects the damping properties of the considered mechanical metamaterials. In particular, we found an inverse relationship between the damping ratio and the absolute value of the Poisson's ratio of the meta-structures. Our results suggest that architected meta-structures similar to those studied could be tailor-made to improve the dissipative performance of mechanical systems. Geometrical design could play an important role in this regard by providing the possibility to tune the various types of quasi-static and dynamic properties of such mechanical metamaterials., Dynamics of Micro and Nano Systems, Biomaterials & Tissue Biomechanics

A jet pump is used to transport a variety of working media and is especially suitable for dredged soil transporting. In this study, a three-dimensional numerical study of a jet pump that is used for slurry delivery was carried out. The characteristics of the internal flow field of the mixing chamber with different working parameters were comprehensively analyzed. The results indicate that the pressure of the axial line decreases with increasing flow ratio (ratio of suction flux and inlet flux) while the pressure of the injected slurry shows a downward trend. With the increase in the flow ratio, the pressure ratio (difference between inlet pressure and suction pressure divided by the difference between exit pressure and suction pressure) falls off while the efficiency presents a parabolic distribution. The pressure ratio can be promoted by properly increasing the length of the mixing chamber so that the available efficiency is broadened. When the mixing chamber length is L = 2.5Dn~4.0Dn (Dn is nozzle outlet diameter), the highly efficient area is wide; in particular, when L = 3.5Dn, the jet slurry pump with the highest efficiency of 27.6% has the best performance., Offshore and Dredging Engineering

Diamagnetic levitation offers stable confinement of an object from its environment at zero power, and thus is a promising technique for developing next generation unclamped resonant sensors. In this work, we realize a resonant weighing scale using a graphite plate that is diamagnetically levitating over a checkerboard arrangement of permanent magnets. We characterize the bending vibrations of the levitating object using laser Doppler vibrometry and use microgram glass beads to calibrate the responsivity of the sensor's resonance frequency to mass changes. The sensor is used for real-time measurement of the evaporation rate of nano-litre droplets with high-accuracy. By analyzing the resonator's frequency stability, we show that the millimeter graphite sensor can reach mass resolutions down to 4.0 ng, relevant to biological and chemical sensing concepts., Dynamics of Micro and Nano Systems, QN/Steeneken Lab

A 3D dynamic numerical model is established for modelling the excavation process for dredging purposes. The interaction between the solid and fluid phases is realized by a specially designed DEM-FVM coupling mechanism, where the fluid-particle interaction forces, the volume fraction information and the particle information are constantly updated and exchanged. Dry and underwater sand cutting simulations are conducted and validated against experimental results. Simulation results of cutting of cohesive soil in atmospheric condition match with the experimental data within acceptable error margin, while the underwater cutting simulations of cohesive soil have not been validated due to the lack of experimental data. Besides, the general applicability of using Discrete Element Modelling (DEM) to create rock samples, and the calibration of DEM rock samples have been investigated, which are essential for conducting atmospheric and underwater rock cutting simulations in the future., Offshore and Dredging Engineering

This paper presents a new 2D water transport model considering capillary suction to predict the water content evolution in the concrete porosity. The basic formulations of the model are illustrated, and a switching algorithm is introduced to simulated wet-drying effects. Two specific absorption tests are studied to validate this model. The first test conducted under room temperature allows to observe that capillary effects play an important role in the concrete material sorptivity and this phenomenon was well captured by the numerical model. The second test conducted under different temperatures highlight that temperature has significant effect on the capillary suction process and it has been considered in the model as an important input parameter.

Editorial - Since the official registration of the word “Mechatronics” as a trademark by Yaskawa Electric Corporation in 1971, explosive growth has been observed in mechatronics research and product development activities. Nowadays, mechatronics and mechatronic design methodologies play increasingly important roles in computer, communication, control, and consumer product (4C) technologies. As such, it is fair to agree that mechatronics technology has profoundly affected almost all aspects of human life, particularly, of engineering realities ranging from rehabilitation devices to ground and underwater robots, and from unmanned aerial vehicles to intelligent manufacturing facilities, constituting a rapidly progressing frontline., 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., Learning & Autonomous Control, Biomechatronics & Human-Machine Control

Diamagnetic levitation is a promising technique for realizing resonant sensors and energy harvesters since it offers thermal and mechanical isolation from the environment at zero power. To advance the application of diamagnetically levitating resonators, it is important to characterize their dynamics in the presence of both magnetic and gravitational fields. Here we experimentally actuate and measure rigid body modes of a diamagnetically levitating graphite plate. We numerically calculate the magnetic field and determine the influence of magnetic force on the resonance frequencies of the levitating plate. By analyzing damping mechanisms, we conclude that eddy current damping dominates dissipation in mm-sized plates. We use finite element simulations to model eddy current damping and find close agreement with experimental results. We also study the size-dependent Q-factors (Qs) of diamagnetically levitating plates and show that Qs above 100 million are theoretically attainable by reducing the size of the diamagnetic resonator down to microscale, making these systems of interest for next generation low-noise resonant sensors and oscillators., Dynamics of Micro and Nano Systems, QN/Steeneken Lab

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility., This article belongs to the Special Issue Feature Papers in Bio-Energy, Offshore and Dredging Engineering

The worldwide crisis in environmental resources, such as deteriorating water resource is intensifying. In Manhattan island, a metropolitan area, the risk is also extremely remarkable. According to the United Nations sustainable development goals, at the current time, more than 2 billion people across the world are living under the crisis of insufficient freshwater resources, due to poor economics or inadequate infrastructures. Likewise, In recent years, the increasing water pollution, mainly due to climate change, aging infrastructures and the regional expansion, have had a significant negative impact on Manhattanites’ habitat and health, which are embodied in the growth pollution level of natural waterways, such as East River and Hudson River. Based on the context, the main objective of this thesis is to research the system of local water systems and the resource crises. Several main questions raised during the study process: What are the causes of the regional resource crisis? What’s the ideological expression of the water infrastructures to Manhattanites? How to ease the climate- induced crisis, or even to end up the emergency by architectural interventions? Within these questions in mind, the main research question is formed: How can the architecture, concerning climatic crisis, cultural loss, evoke a more livable and healthier community for NE Midtown’s future development?, Complex projects, Midtown Manhattan, Architecture, Urbanism and Building Sciences | Complex Projects

Editorial - Since the official registration of the word “Mechatronics” as a trademark by Yaskawa Electric Corporation in 1971, explosive growth has been observed in mechatronics research and product development activities. Nowadays, mechatronics and mechatronic design methodologies play increasingly important roles in computer, communication, control, and consumer product (4C) technologies. As such, it is fair to agree that mechatronics technology has profoundly affected almost all aspects of human life, particularly, of engineering realities ranging from rehabilitation devices to ground and underwater robots, and from unmanned aerial vehicles to intelligent manufacturing facilities, constituting a rapidly progressing frontline., 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., Learning & Autonomous Control, Biomechatronics & Human-Machine Control

Diamagnetic levitation is a promising technique for realizing resonant sensors and energy harvesters since it offers thermal and mechanical isolation from the environment at zero power. To advance the application of diamagnetically levitating resonators, it is important to characterize their dynamics in the presence of both magnetic and gravitational fields. Here we experimentally actuate and measure rigid body modes of a diamagnetically levitating graphite plate. We numerically calculate the magnetic field and determine the influence of magnetic force on the resonance frequencies of the levitating plate. By analyzing damping mechanisms, we conclude that eddy current damping dominates dissipation in mm-sized plates. We use finite element simulations to model eddy current damping and find close agreement with experimental results. We also study the size-dependent Q-factors (Qs) of diamagnetically levitating plates and show that Qs above 100 million are theoretically attainable by reducing the size of the diamagnetic resonator down to microscale, making these systems of interest for next generation low-noise resonant sensors and oscillators., Dynamics of Micro and Nano Systems, QN/Steeneken Lab

Bioethanol synthesis techniques have been studied intensively due to the energy crisis and various environmental concerns. A two-step bioethanol production process was carried out multiple times in an unbaffled agitator tank. The parameters varied, including the fermentation temperature, the pH level, the amount of yeast, and the impeller type. Then, a simulation was used to obtain an image of the agitation behavior inside the agitator tank to compare the velocity profile of each type of impeller design. The impeller with eight blades was found to produce the highest flow velocity: 0.28 m/s. The highest concentration of bioethanol generated from the fermentation was 34 g/L, which was produced by using an eight-blade impeller at 30 °C, a pH level of 5, an agitation speed of 70 rpm, and 2 wt % yeast. The two-blade impeller produced the lowest bioethanol concentration, 18 g/L, under the same conditions. Ethanol concentration was found to peak at 40 °C and a pH level of 5. The geometry of the impeller, the fermentation temperature, and the pH level were each found to have a significant effect on the resulting bioethanol concentration according to the results of an ANOVA test. The amount of yeast had no effect on the fermentation reaction. Finally, the results demonstrated the possibility of using computational fluid dynamic modeling to determine the impeller’s behavior for the development of the bioethanol fermentation process. The simulation and experimental results from this research support the scaling up of a bioethanol production facility., This article belongs to the Special Issue Feature Papers in Bio-Energy, Offshore and Dredging Engineering

The worldwide crisis in environmental resources, such as deteriorating water resource is intensifying. In Manhattan island, a metropolitan area, the risk is also extremely remarkable. According to the United Nations sustainable development goals, at the current time, more than 2 billion people across the world are living under the crisis of insufficient freshwater resources, due to poor economics or inadequate infrastructures. Likewise, In recent years, the increasing water pollution, mainly due to climate change, aging infrastructures and the regional expansion, have had a significant negative impact on Manhattanites’ habitat and health, which are embodied in the growth pollution level of natural waterways, such as East River and Hudson River. Based on the context, the main objective of this thesis is to research the system of local water systems and the resource crises. Several main questions raised during the study process: What are the causes of the regional resource crisis? What’s the ideological expression of the water infrastructures to Manhattanites? How to ease the climate- induced crisis, or even to end up the emergency by architectural interventions? Within these questions in mind, the main research question is formed: How can the architecture, concerning climatic crisis, cultural loss, evoke a more livable and healthier community for NE Midtown’s future development?, Complex projects, Midtown Manhattan, Architecture, Urbanism and Building Sciences | Complex Projects

This paper describes a method of determining the reaction forces of a vertical structure with an overhang to impulsive wave impacts. The aim is to develop a method to design a hydraulic structure exposed to the impulsive wave impact. At present, there is a lack of guidelines on the designing and verification with such a purpose. The impulse of the impact is taken as the primary design variable to estimate the impulsive reaction force instead of peak impact forces. By using extreme value analysis (EVA), the characteristic impulse (e.g., I im,0.1% ) can be determined. Then a simple structure model is used for obtaining reaction forces to the characteristic impact impulse. The sum of the impulsive reaction force and the quasi-steady wave force could represent the total reaction force, which can be used as a design load on the structure. The advantage of using the impact impulse could give an approach in which several aspects of the impulsive wave impact force can be incorporated better, like determining the exceedance probability of a certain load, incorporating the flexibility of the structure and correcting possible scale effects in small scale hydraulic models. The proposed method based on the characteristic value of the I im,0.1% is applied to forces measured in a small scale model of the Afsluitdijk discharge sluice, and compared well to a full-time domain solution. The results indicate the initial assumption that using the impact impulse of the impact as the primary design variable, it is possible to estimate the dynamic response of the structure., Accepted Author Manuscript, Hydraulic Structures and Flood Risk

Mass balance analysis of ice sheets is a key component to understand the effects of global warming. A significant component of ice sheet and shelf mass balance is iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Such iceberg-tsunamis have reached amplitudes of 50 m and destroyed harbours. Calving icebergs interact with the surrounding water through different mechanisms and we investigate five; A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity-dominated overturning and E: buoyancy-dominated overturning. Gravity-dominated icebergs essentially fall into the water body whereas buoyancy-dominated icebergs rise to the water surface. We find with unique large-scale laboratory experiments that iceberg-tsunami heights from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from A, C and E. A theoretical model for released iceberg energy supports this finding and the measured wave periods upscaled to Greenlandic outlet glaciers agree with field observations. Whilst existing empirical equations for landslide-tsunamis establish estimates of an upper envelope of the maximum iceberg-tsunami heights, they fail to capture the physics of most iceberg-tsunami mechanisms., Hydraulic Structures and Flood Risk

As the bridge stock in The Netherlands and Europe is ageing, various methods to analyse the capacity of existing bridges are being studied. Proof load testing is one of the method to test the capacity of bridges by applying loads on the existing concrete bridges with small spans. Because of the fact that neither the actual traffic load nor the design traffic load required by Eurocode can be directly applied on the target bridge in real-life proof load testing, an equivalent wheel load has to be applied instead. The magnitude and the location of the equivalent wheel load is determined in such a way that it generates the same magnitude of inner forces in the cross section. Such calculation is usually done by linear finite element analyses (FEA). Whereas, different bridges have different geometry such as length, width, thickness, skewness, number of spans and lanes etc. For each configuration, FEA has to be done first to determine the loading position. The main aim of this paper is to study the relation between bridge geometry and unfavourable loading positions. Based on that, a guidance tool is developed for the determination of the critical proof load testing locations for the practice. To achieve this goal, a Python script has been developed using the general purpose FEM platform DIANA FEA. The script enables the automatic generation and analysis of a bridge model with different geometries and loading conditions. By applying the Eurocode Load Model 1 (LM1) at variable locations, the most unfavourable loading positions for the proof load are obtained at the corresponding boundary conditions. The output of the study provides a convenient tool for future proof load testing., Concrete Structures

Slurry transport is a very important means of transporting solids through a pipeline. To improve the efficiency of slurry transport, especially in coarse particle transport, which is subject to problems such as strong resistance and easy blockage, more of the internal structure of the flow must be known. Empirical and analytical models are inadequate for this purpose. Therefore, in this study, a coupling mechanism is established between the computational fluid dynamics (CFD) and discrete element method (DEM). The CFD-DEM coupling was applied and research was conducted on the internal flow structure characteristics of microscopic motion and flow transition for coarse particles in a pipeline. The flow-regime transition processes of coarse 10-mm particles were analyzed qualitatively at velocities of 2 m·s −1 , 5 m·s −1 , 8 m·s −1 and 10 m·s −1 in a 0.1524-m diameter pipe, and quantitative analyses were performed on both the concentration distribution and the pressure gradient of particles in regimes of fixed bed flow, sliding bed flow and heterogeneous flow. Moreover, from the perspective of force analysis of particles, the law of sedimentation movement of particles is discussed, and the reason for the change in concentration distribution is explained. The research presented here provides insight into the internal structure of the flow and gives quantitative indications of pressure gradient and concentration distributions., Offshore and Dredging Engineering

This paper describes a method of determining the reaction forces of a vertical structure with an overhang to impulsive wave impacts. The aim is to develop a method to design a hydraulic structure exposed to the impulsive wave impact. At present, there is a lack of guidelines on the designing and verification with such a purpose. The impulse of the impact is taken as the primary design variable to estimate the impulsive reaction force instead of peak impact forces. By using extreme value analysis (EVA), the characteristic impulse (e.g., I im,0.1% ) can be determined. Then a simple structure model is used for obtaining reaction forces to the characteristic impact impulse. The sum of the impulsive reaction force and the quasi-steady wave force could represent the total reaction force, which can be used as a design load on the structure. The advantage of using the impact impulse could give an approach in which several aspects of the impulsive wave impact force can be incorporated better, like determining the exceedance probability of a certain load, incorporating the flexibility of the structure and correcting possible scale effects in small scale hydraulic models. The proposed method based on the characteristic value of the I im,0.1% is applied to forces measured in a small scale model of the Afsluitdijk discharge sluice, and compared well to a full-time domain solution. The results indicate the initial assumption that using the impact impulse of the impact as the primary design variable, it is possible to estimate the dynamic response of the structure., Accepted Author Manuscript, Hydraulic Structures and Flood Risk

Slurry transport is a very important means of transporting solids through a pipeline. To improve the efficiency of slurry transport, especially in coarse particle transport, which is subject to problems such as strong resistance and easy blockage, more of the internal structure of the flow must be known. Empirical and analytical models are inadequate for this purpose. Therefore, in this study, a coupling mechanism is established between the computational fluid dynamics (CFD) and discrete element method (DEM). The CFD-DEM coupling was applied and research was conducted on the internal flow structure characteristics of microscopic motion and flow transition for coarse particles in a pipeline. The flow-regime transition processes of coarse 10-mm particles were analyzed qualitatively at velocities of 2 m·s −1 , 5 m·s −1 , 8 m·s −1 and 10 m·s −1 in a 0.1524-m diameter pipe, and quantitative analyses were performed on both the concentration distribution and the pressure gradient of particles in regimes of fixed bed flow, sliding bed flow and heterogeneous flow. Moreover, from the perspective of force analysis of particles, the law of sedimentation movement of particles is discussed, and the reason for the change in concentration distribution is explained. The research presented here provides insight into the internal structure of the flow and gives quantitative indications of pressure gradient and concentration distributions., Offshore and Dredging Engineering

As the bridge stock in The Netherlands and Europe is ageing, various methods to analyse the capacity of existing bridges are being studied. Proof load testing is one of the method to test the capacity of bridges by applying loads on the existing concrete bridges with small spans. Because of the fact that neither the actual traffic load nor the design traffic load required by Eurocode can be directly applied on the target bridge in real-life proof load testing, an equivalent wheel load has to be applied instead. The magnitude and the location of the equivalent wheel load is determined in such a way that it generates the same magnitude of inner forces in the cross section. Such calculation is usually done by linear finite element analyses (FEA). Whereas, different bridges have different geometry such as length, width, thickness, skewness, number of spans and lanes etc. For each configuration, FEA has to be done first to determine the loading position. The main aim of this paper is to study the relation between bridge geometry and unfavourable loading positions. Based on that, a guidance tool is developed for the determination of the critical proof load testing locations for the practice. To achieve this goal, a Python script has been developed using the general purpose FEM platform DIANA FEA. The script enables the automatic generation and analysis of a bridge model with different geometries and loading conditions. By applying the Eurocode Load Model 1 (LM1) at variable locations, the most unfavourable loading positions for the proof load are obtained at the corresponding boundary conditions. The output of the study provides a convenient tool for future proof load testing., Concrete Structures

Mass balance analysis of ice sheets is a key component to understand the effects of global warming. A significant component of ice sheet and shelf mass balance is iceberg calving, which can generate large tsunamis endangering human beings and coastal infrastructure. Such iceberg-tsunamis have reached amplitudes of 50 m and destroyed harbours. Calving icebergs interact with the surrounding water through different mechanisms and we investigate five; A: capsizing, B: gravity-dominated fall, C: buoyancy-dominated fall, D: gravity-dominated overturning and E: buoyancy-dominated overturning. Gravity-dominated icebergs essentially fall into the water body whereas buoyancy-dominated icebergs rise to the water surface. We find with unique large-scale laboratory experiments that iceberg-tsunami heights from gravity-dominated mechanisms (B and D) are roughly an order of magnitude larger than from A, C and E. A theoretical model for released iceberg energy supports this finding and the measured wave periods upscaled to Greenlandic outlet glaciers agree with field observations. Whilst existing empirical equations for landslide-tsunamis establish estimates of an upper envelope of the maximum iceberg-tsunami heights, they fail to capture the physics of most iceberg-tsunami mechanisms., Hydraulic Structures and Flood Risk

This paper addresses a travel time reliable signal control problem. Travel time distributional estimates are obtained from a stochastic microscopic traffic simulator. The estimates are embedded within a simulation-based optimization algorithm. Analytical approximations of the simulated metrics are combined with the simulated data in order to enhance the computational efficiency of the algorithm. The signal control problems are formulated based on the expectation and the standard deviation of travel time metrics. The proposed approach goes beyond the traditional use of first-order simulated information, it addresses a problem that embeds higher-order distributional information. It is used to solve a large-scale signal control problem. The approach addresses these challenging simulation-based optimization problems in a computationally efficient manner. Its performance is compared to that of a traditional simulation-based optimization approach. The proposed method systematically outperforms the traditional approach. Such an approach can be used to informthe design and operations of transportation systems by, for instance, addressing reliable and/or robust formulations of traditional transportation problems., 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

Overtopping bore impact forces on a dike mounted vertical wall were measured in similar large-scale (Froude length scale factor 1-to-4.3) and small-scale (Froude length scale factor 1-to-25) models. The differences due to scale effects were studied, by comparing the up-scaled force measurements from both models in prototype. It was noted that if a minimum layer thickness, velocity of the overtopping flow and water depth at the dike toe were maintained in the small-scale model, the resulting differences in impact force due to scale effects are within the range of differences due to non-repeatability and model effects., Accepted Author Manuscript, Hydraulic Structures and Flood Risk

Sensitive materials for formaldehyde (HCHO) sensor need high sensitivity and selectivity. The research on two dimensional (2D) sensitive material is growing, and most studies focus on the pristine or modified graphene. So it is essential to introduce other 2D materials into HCHO gas sensor. In this report, the adsorption behaviors of organic gas molecules including C2H6, C2H4, C2H2, C6H6, C2H5OH and HCHO over indium triphosphide (InP3) monolayer were studied by using first-principle atomistic simulations. The calculation results demonstrate that InP3 monolayer has a high sensitivity and selectivity to HCHO than others. By comparing the structures and adsorption results of InP3 monolayer, graphene and single-layered MoS2, it was found that the polarity bonds and steric effect of the site on monolayer play an important role in the detection of HCHO. The effect of strain on the gas/substrate adsorption systems was also studied, implying that the stained InP3 monolayer could enhance the sensitivity and selectivity to HCHO. This study provides useful insights into the gas-surface interaction that may assist future experimental development of 2D material for HCHO sensing and performance optimization based on strain., Accepted author manuscript, Electronic Components, Technology and Materials

Sensitive materials for formaldehyde (HCHO) sensor need high sensitivity and selectivity. The research on two dimensional (2D) sensitive material is growing, and most studies focus on the pristine or modified graphene. So it is essential to introduce other 2D materials into HCHO gas sensor. In this report, the adsorption behaviors of organic gas molecules including C2H6, C2H4, C2H2, C6H6, C2H5OH and HCHO over indium triphosphide (InP3) monolayer were studied by using first-principle atomistic simulations. The calculation results demonstrate that InP3 monolayer has a high sensitivity and selectivity to HCHO than others. By comparing the structures and adsorption results of InP3 monolayer, graphene and single-layered MoS2, it was found that the polarity bonds and steric effect of the site on monolayer play an important role in the detection of HCHO. The effect of strain on the gas/substrate adsorption systems was also studied, implying that the stained InP3 monolayer could enhance the sensitivity and selectivity to HCHO. This study provides useful insights into the gas-surface interaction that may assist future experimental development of 2D material for HCHO sensing and performance optimization based on strain., Accepted author manuscript, Electronic Components, Technology and Materials

The sensing behavior of monolayer tin sulfide (SnS) for four gas molecules (NH3, NO2, CO, and H2O) are studied by the first-principle calculation based on density-functional theory. We calculate adsorption energy, adsorption distance, and Hirshfeld charge to estimate the adsorption ability of monolayer SnS for these gas molecules. The results demonstrate that all the gas molecules show physisorption nature. We further calculate the current-voltage (I -V ) curves using the nonequilibrium Green's function formalism for evaluating the NO2 gas sensing properties. The monolayer SnS is found to be strongly sensitive to NO2 molecule dependent on moderate adsorption energy, excellent charge transfer, and significant change of I -V property before and after gas adsorption. Therefore, we suggest that monolayer SnS can be a prominent candidate for application as NO2 gas sensor., Accepted author manuscript, Electronic Components, Technology and Materials

Overtopping wave loads on vertical structures on top of a dike have been investigated in several small scale experiments in the past. A large-scale validation for a mild foreshore situation is still missing. Hence the WALOWA experimental campaign was carried out to address this topic. In the present paper the objectives of the WALOWA project are outlined in detail, the model and measurement set-up described and the test program presented. Furthermore, preliminary results featuring a single 1000 irregular waves test of the test program are highlighted. This includes the study of the mild and sandy foreshore evolution by comparing profiles before and after the test execution. The profile measurements are obtained with a mechanical profiler. The wave parameters offshore and at the dike toe are numerically simulated using a SWASH model. The numerical results are validated against the measurements. Finally, the force and pressure time series of the waves impacting against the wall are processed and filtered. The load cell measurements and the time series of integrated pressures are compared to each other and for each impact event the maximum force is derived., Hydraulic Structures and Flood Risk, Environmental Fluid Mechanics

On coastal dikes in Belgium, many residential buildings are found. Most of the old buildings are masonry structures with two to three floors (Figure 1). The ground floors are always elevated (Figure 2), and the entrances of the basements are closed by shutters (Figure 3). The most modern buildings are concrete reinforcement structures with concrete piles/columns as foundations. The walls are consisting of masonry or concrete. These buildings are 5 to 9 floors high. Some of the ground floors are elevated, and some are used as cafe, restaurant or store. The ground floors are equipped with large glass windows and doors., Environmental Fluid Mechanics, Hydraulic Structures and Flood Risk

The vulnerability of buildings on coastal dikes due to overtopping wave impacts is difficult to assess. A method is developed in this paper to quantify the vulnerability of masonry buildings on a coastal dike exposed to wave overtopping. Using previous studies, the accidental loads due to the extreme wave impacts are characterized. Using the approach from Eurocode 6, the strength of masonry buildings under these loads is assessed. Results from a case study in Belgium show that masonry buildings located 10–15 m away from the seafront would suffer from localized damage, such as windows being broken under a 1000 year storm. The building would collapse under a 10,000-year storm. The method can be used to assess the safety of existing buildings on coastal dikes and to design new buildings., Hydraulic Structures and Flood Risk, Steel & Composite Structures, Environmental Fluid Mechanics

In low-lying countries like the Netherlands and Belgium, coastal areas are often highly urbanized, and buildings are often built on or close to the flood defenses (Figure 2 shows a typical Belgian seaside town). This is an example of multifunctional flood defense, where urban functions are integrated with flood defense structures. In this example, the wide crest of the coastal dike is used as a promenade with building frontage. However, policy makers as well as the users and owners of the properties may be unaware of possible overtopping effects, and they may lack records of wave overtopping and the potential direct damage it can cause. The goal of this research project was to develop a tool that can measure the risks and potential cost of wave overtopping events on buildings., Hydraulic Structures and Flood Risk

Additional thesis - Historical engineering works such as weirs, land reclamation and large scale deepening modified not only the local morphology and hydrodynamics but also tidal characteristics and sediment transport patterns in the tidal river Ems. The loss of intertidal area and ongoing deepening contribute to the flood dominance while decreasing the river’s flushing capacity and enhance tidal amplification. The increased tidal asymmetry continuously pumping and accumulating fine sediment upstream into the Ems River system. This river is renowned for its high suspended fine sediment concentration and such high concentration work together with an increasing water depth for a reduction of the river hydraulic roughness. In order to investigate the key factor that contributes to the time lag of high water occurrence along the river, a depth-averaged 2DH hydrodynamic Delft3D model is applied. The results of the numerical studies indicate both the increasing of upstream discharge and the reduction of hydraulic roughness contribute to a smaller time lag of high water between Papenburg and Emden. However, if the tidal weir at Herbrum is removed or the Manning coefficient for the bottom roughness is increased, the discharge almost has no impact on the time lag of high water occurrence at Emden and Papenburg., Civil Engineering and Geosciences, Hydraulic Engineering

During the last decades, the spectral wave period Tm-1,0 has become accepted as a characteristic wave period when describing the hydraulic attack on coastal structures, especially over shallow foreshores. In this study, we derive an empirical prediction formula for Tm-1,0 on shallow to extremely shallow foreshores with a mild slope. The formula was determined based on flume tests and numerical calculations, mainly for straight linear foreshore slopes. It is shown that the wave period increases drastically when the water depth decreases; up to eight times the offshore value. The bed slope angle influences the wave period slightly. For short-crested wave fields, the strong increase of Tm-1,0 starts closer to shore (at smaller water depths) than for long-crested wave fields., Environmental Fluid Mechanics, Hydraulic Structures and Flood Risk

For a design purpose, this study mainly focuses on the channel resistance with different spatial distribution of the vegetation patches. Even under the same blockage factor, the total patch numbers in the channel, the distance between two vegetation patches both in the lateral and longitudinal direction as well as the length ratio of patches would have an influence of channel resistance. The increase of the lateral interfacial area and the increase of the total leading edge would contribute to a significant increase of channel resistance. Compared to the channel with emergent patches, the resistance of channel with submerged vegetation is less sensitive to the spatial distribution patterns., Civil Engineering and Geosciences, Hydraulic Engineering

Bij het ontwerp van multifunctionele waterkeringen spelen twee specifieke constructieve aspecten een rol: golfimpact en constructieve verificatie. Een onderzoeksprogramma van de TU Delft, Universiteit van Twente en Wageningen Universiteit heeft zich hierover gebogen., Hydraulic Structures and Flood Risk, Environmental Fluid Mechanics, Policy Analysis

On coastal dikes in Belgium, many residential buildings are found. Most of the old buildings are masonry structures with two to three floors (Figure 1). The ground floors are always elevated (Figure 2), and the entrances of the basements are closed by shutters (Figure 3). The most modern buildings are concrete reinforcement structures with concrete piles/columns as foundations. The walls are consisting of masonry or concrete. These buildings are 5 to 9 floors high. Some of the ground floors are elevated, and some are used as cafe, restaurant or store. The ground floors are equipped with large glass windows and doors., Environmental Fluid Mechanics, Hydraulic Structures and Flood Risk

The vulnerability of buildings on coastal dikes due to overtopping wave impacts is difficult to assess. A method is developed in this paper to quantify the vulnerability of masonry buildings on a coastal dike exposed to wave overtopping. Using previous studies, the accidental loads due to the extreme wave impacts are characterized. Using the approach from Eurocode 6, the strength of masonry buildings under these loads is assessed. Results from a case study in Belgium show that masonry buildings located 10–15 m away from the seafront would suffer from localized damage, such as windows being broken under a 1000 year storm. The building would collapse under a 10,000-year storm. The method can be used to assess the safety of existing buildings on coastal dikes and to design new buildings., Hydraulic Structures and Flood Risk, Steel & Composite Structures, Environmental Fluid Mechanics

Een onderzoeksprogramma van de TU Delft, Universiteit van Twente en Wageningen Universiteit heeft diverse ontwerpaspecten van zogenoemde multifunctionele waterkeringen onder de loep genomen. Dit artikel belicht het technisch en ruimtelijk ontwerpproces van dergelijke keringen, en het betrekken van stakeholders in dit proces., Hydraulic Structures and Flood Risk, Policy Analysis, Environmental Fluid Mechanics

Additional thesis - Historical engineering works such as weirs, land reclamation and large scale deepening modified not only the local morphology and hydrodynamics but also tidal characteristics and sediment transport patterns in the tidal river Ems. The loss of intertidal area and ongoing deepening contribute to the flood dominance while decreasing the river’s flushing capacity and enhance tidal amplification. The increased tidal asymmetry continuously pumping and accumulating fine sediment upstream into the Ems River system. This river is renowned for its high suspended fine sediment concentration and such high concentration work together with an increasing water depth for a reduction of the river hydraulic roughness. In order to investigate the key factor that contributes to the time lag of high water occurrence along the river, a depth-averaged 2DH hydrodynamic Delft3D model is applied. The results of the numerical studies indicate both the increasing of upstream discharge and the reduction of hydraulic roughness contribute to a smaller time lag of high water between Papenburg and Emden. However, if the tidal weir at Herbrum is removed or the Manning coefficient for the bottom roughness is increased, the discharge almost has no impact on the time lag of high water occurrence at Emden and Papenburg., Civil Engineering and Geosciences, Hydraulic Engineering

In low-lying countries like the Netherlands and Belgium, coastal areas are often highly urbanized, and buildings are often built on or close to the flood defenses (Figure 2 shows a typical Belgian seaside town). This is an example of multifunctional flood defense, where urban functions are integrated with flood defense structures. In this example, the wide crest of the coastal dike is used as a promenade with building frontage. However, policy makers as well as the users and owners of the properties may be unaware of possible overtopping effects, and they may lack records of wave overtopping and the potential direct damage it can cause. The goal of this research project was to develop a tool that can measure the risks and potential cost of wave overtopping events on buildings., Hydraulic Structures and Flood Risk