Search

The observed phase in time series of interferometric synthetic aperture radar (InSAR) products is a superposition of various components. Differential topography, line-of-sight displacements, and differential atmospheric delays are the main contributions and need to be disentangled to derive accurate digital elevation model (DEM), deformation, or atmospherical products from InSAR. However, isolating the atmospheric component has been proven difficult as it is spatiotemporally highly dynamic and a superposition of two atmospheric states. Here, we propose an approach to parameterize the stochastic properties of the single-epoch atmospheric delay field as a way to define the atmospheric signal. We found that the atmospheric signal of a time series of interferograms can be characterized by structure functions, which can be used to isolate the single-epoch structure functions. Due to the scaling properties of the atmospheric signal, it is then possible to construct a parametric function per SAR acquisition, using two isotropic and three anisotropic parameters. In particular, the isotropic parameters for the short-distance variation and long-distance variation in atmospheric delay can be used to characterize the atmospheric signal. For a test set of 151 Sentinel-1 acquisitions, this results in an atmospheric energy range of about 10 for short-distance scales and about 50 for long-distance scales. Our parameterization demonstrates that we can describe the spatiotemporal variability of InSAR atmospheric delays, which provides a measure for atmospheric noise for individual epochs in deformation time series based on distance and azimuth., Geoscience and Remote Sensing, Mathematical Geodesy and Positioning

The principal aim of the work presented here is to investigate and demonstrate that a forward tilted rowing blade would result in a more efficient and effective motion of the blade through the water that would result in a higher boat speed when an equal input power is provided. A 1:5 scaled rowing boat is used to determine the performance of rowing blades with different sizes and blade angles. This is used to validate the results of a previous study where the optimal blade angle of 15 (Formula presented.) with respect to the oar shaft was determined (1). The input power and speed of the rowing boat can be compared between original and modified oar blades. Measurements in a towing tank demonstrate that a modified rowing blade result in faster rowing by 0.4% at the same input power. Maintaining the same stroke rate, the improvement of the blade efficiency is compensated by using a 4–6% increased blade area to yield the same input power., Fluid Mechanics

Numerical weather prediction (NWP) models are used to predict the weather based on current observations in combination with physical and mathematical models. Yet, they are limited by the spatial density and the accuracy of the available observations. Satellite radar interferometry (InSAR) is known to be extremely sensitive to the 3D atmospheric refractivity distribution, and has a high spatial resolution, providing information that can be used for assimilation in NWP models. However, due to the inherent superposition of two or more atmospheric states, only biased and temporally differenced signals can be retrieved, that can also be contaminated by deformation signals and decorrelation. Here we present a method to estimate single-epoch absolute atmospheric delays by combining InSAR time series with prior NWP model prediction time series, using a constrained least-squares estimation. We show that this leads to a solution that reliably extracts the single-epoch relative delays from InSAR data and uses prior NWP model data to find the absolute reference for these delays, while mitigating long-term deformation and decorrelation signal. This approach leads to repetitive delay updates with a spatial resolution of 500 m, that can be directly assimilated into numerical weather models., Mathematical Geodesy and Positioning

Item does not contain fulltext, De afgelopen decennia is vooral aandacht besteed aan het ontwikkelen van de inhoud van het vak van preventie en gezondheidsbevordering (GB). Er is nauwelijks geïnvesteerd in de professional zelf en in voldoende professionals om preventie en GB impact te laten hebben. De huidige complexe volksgezondheidsproblemen vragen echter om kundige professionals die weten hoe complexe vraagstukken aangepakt kunnen worden. De gamechanger voor de volksgezondheid 2030 die wij voorstellen is een netwerk van een nieuw type volksgezondheidsexperts die vanuit een collectieve benadering en gesteund door een stevige preventiestructuur collectieve impact kunnen realiseren. English abstract: In recent decades, particular attention has been paid to developing the content of the profession of prevention and health promotion (HP). Hardly any investment has been made in the professional himself and in sufficient professionals to allow prevention and HP to have an impact. However, today's complex public health problems require skilled professionals who know how to tackle complex issues. The 2030 gamechanger for public health that we propose is a network of a new type of public health experts who can realize collective impact from a collective impact approach and supported by a solid infrastructure for prevention.

Contains fulltext : 287266.pdf (Publisher’s version ) (Closed access), De afgelopen decennia is vooral aandacht besteed aan het ontwikkelen van de inhoud van het vak van preventie en gezondheidsbevordering (GB). Er is nauwelijks geïnvesteerd in de professional zelf en in voldoende professionals om preventie en GB impact te laten hebben. De huidige complexe volksgezondheidsproblemen vragen echter om kundige professionals die weten hoe complexe vraagstukken aangepakt kunnen worden. De gamechanger voor de volksgezondheid 2030 die wij voorstellen is een netwerk van een nieuw type volksgezondheidsexperts die vanuit een collectieve benadering en gesteund door een stevige preventiestructuur collectieve impact kunnen realiseren. English abstract: In recent decades, particular attention has been paid to developing the content of the profession of prevention and health promotion (HP). Hardly any investment has been made in the professional himself and in sufficient professionals to allow prevention and HP to have an impact. However, today's complex public health problems require skilled professionals who know how to tackle complex issues. The 2030 gamechanger for public health that we propose is a network of a new type of public health experts who can realize collective impact from a collective impact approach and supported by a solid infrastructure for prevention.

Sodium-ion batteries (SIBs) have been heralded as the most promising “beyond lithium” energy storage technology. This proclamation is based on recent technological trends and the outstanding performance of the state-of-the-art prototype 18650 and pouch cells. However, improving the design and performance of SIBs requires an in-depth understanding of the electrochemical behavior of the electrodes from both an experimental and physics-based modeling perspective. In this contribution, experimental characterizations of SIB electrode materials based on Na3V2(PO4)2F3 (NVPF) cathode and hard carbon (HC) anode are presented. The goal of this experimental investigation is to understand the individual electrode behavior and further elucidate relevant parameters for physics-based models. As a result, geometric, thermodynamic, and kinetic parameters are deduced from the two SIB electrodes. Based on the analyses of Na//NVPF and Na//HC half-cells, diffusion mass transport limitations and Ohmic losses are identified for both electrodes. These overpotential losses are equally present in full cell SIBs composed of NVPF and HC electrodes. These results are useful in the setup of SIB physics-based models.

Sodium-ion batteries (SIBs) have recently been proclaimed as the frontrunner 'post lithium' energy storage technology. This is because SIBs share similar performance metrics with lithium-ion batteries, and sodium is 1000 times more abundant than lithium. In order to understand the electrochemical characteristics of SIBs and improve present-day designs, physics-based models are necessary. Herein, a physics-based, pseudo-two-dimensional (P2D) model is introduced for SIBs for the first time. The P2D SIB model is based on Na3V2(PO4)2F3 (NVPF) and hard carbon (HC) as positive and negative electrodes, respectively. Charge transfer in the NVPF and HC electrodes is described by concentration-dependent diffusion coefficients and kinetic rate constants. Parametrization of the model is based on experimental data and genetic algorithm optimization. It is shown that the model is highly accurate in predicting the discharge profiles of full cell HC//NVPF SIBs. In addition, internal battery states, such as the individual electrode potentials and concentrations, can be obtained from the model at applied currents. Several key challenges in both electrodes and the electrolyte are herein unraveled, and useful design considerations to improve the performance of SIBs are highlighted.

Gold is a rarity in archaeological research, and its prehistoric presence is often used to infer the existence of persons of extraordinary standing (Warmenbol 2004: 208 & 219). It therefore is a fitting topic to congratulate a colleague that we hold in extraordinary regard; our questions to Eugène on the Later Prehistoric archaeology and bronze artefacts of Belgium were never posed in vain and his constructive comments on our publications never missed their mark. In his honor, we present an overview of the prehistoric gold from the Late Neolithic up to the Early Iron Age from the Netherlands – another case in point of how we could build on foundations put in place by Eugène (esp. Warmenbol 1989: 509; Warmenbol 2004). An open access dataset comprising the full descriptions for the individual objects can be found here: https://doi.org/10.34894/8SQK5F. In this contribution we have discussed the few but notable gold finds datable from the Late Neolithic up to Early Iron Age from the Netherlands. Despite being low in numbers, a few trends come to the fore: both around 2300-2000 BCE and 1600-1400 BCE, gold ornaments are used in funerary context as markers of a special social standing, possibly related to interregional contacts and/or martial identities. The position of gold ornaments in both horizon 1 and 2 suggest that these are head-decorations, possible wrapped around locks or breads of hair, with the possible exception of the diadem (or neckring?) of Ede – Bennekom. In horizon 3, gold ornaments are no longer placed solely in graves, but – akin to their bronze counterparts – also deposited in wetland locations in the landscape. In this period, their association to weaponry (apart obviously of the gold inlay of the Oss sword; Van der Vaart-Verschoof 2017a: 122-124) appears to be lost, and small-diameter gold and gilded rings of unknown original usage (nose? ear? hair?) are added to cremated remains in urnfield period ceramic vessels. Their scarce occurrenc

This article describes the observation techniques and suggests processing methods to estimate dynamical sea-ice parameters from data of the Earth Explorer 10 candidate Harmony. The two Harmony satellites will fly in a reconfigurable formation with Sentinel-1D. Both will be equipped with a multi-angle thermal infrared sensor and a passive radar receiver, which receives the reflected Sentinel-1D signals using two antennas. During the lifetime of the mission, two different formations will be flown. In the stereo formation, the Harmony satellites will fly approximately 300km in front and behind Sentinel-1, which allows for the estimation of instantaneous sea-ice drift vectors. We demonstrate that the addition of instantaneous sea-ice drift estimates on top of the daily integrated values from feature tracking have benefits in terms of interpretation, sampling and resolution. The wide-swath instantaneous drift observations of Harmony also help to put high-temporal-resolution instantaneous buoy observations into a spatial context. Additionally, it allows for the extraction of deformation parameters, such as shear and divergence. As a result, Harmony's data will help to improve sea-ice statistics and parametrizations to constrain sea-ice models. In the cross-track interferometry (XTI) mode, Harmony's satellites will fly in close formation with an XTI baseline to be able to estimate surface elevations. This will allow for improved estimates of sea-ice volume and also enables the retrieval of full, two-dimensional swell-wave spectra in sea-ice-covered regions without any gaps. In stereo formation, the line-of-sight diversity allows the inference of swell properties in both directions using traditional velocity bunching approaches. In XTI mode, Harmony's phase differences are only sensitive to the ground-range direction swell. To fully recover two-dimensional swell-wave spectra, a synergy between XTI height spectra and intensity spectra is required. If selected, the Harmony, Mathematical Geodesy and Positioning

Electrolytes play an integral role in the successful operation of any battery chemistry. The reemergence of the sodium-ion battery (SIB) chemistry has therefore rejuvenated the search for optimized SIB salts and solvents. Recent experiments have found that 1 M NaPF6 in ethylene carbonate (EC) and propylene carbonate (PC), EC0.5:PC0.5 (w/w) is the best binary electrolyte for SIBs. However, mathematical models, to elucidate these experimental findings, have so far been lacking. Furthermore, no attempts to understand the effect of EC composition on the conductivity and electrolyte stability have been performed. Herein, the viscosity and conductivity profiles of NaPF6 in EC0.5:PC0.5 electrolyte are unraveled, using experimental and modeling approaches at different temperatures and salt concentrations. The viscosity is measured in a double-wall Couette cell and for the first time, the ionic conductivity is determined using two Pt blocking electrodes in a PAT-Cell electrochemical setup. Modeling is performed using the Advanced Electrolyte Model (AEM), a statistical mechanics software. It is shown that the conductivity and viscosity relationship follows a simple Stokes' law even at a low temperatures and high concentrations. In addition, the stability of binary and ternary electrolytes on hard carbon is shown to correlate with the preferential ion solvation of EC.

The simplified gravimetric intermittent titration technique (GITT) model, which was first proposed by Weppner and Huggins in 1977, remains a popular method to determine the solid-state diffusion coefficient (D1) and the electrochemical kinetic rate constant (k). This is despite the model having been developed on the premise of a single-slab electrode and other gross simplification which are not applicable to modern-day porous battery electrodes. Recently however, more realistic and conceptually descriptive models have emerged, which make use of the increased availability of computational power. Chief among them is the P2D model developed by Newman et al., which has been validated for various porous battery electrodes. Herein, a P2D GITT model is presented and coupled with grid search optimization to determine state-of-charge (SOC) dependent D1 and k parameters for a sodium-ion battery (SIB) cathode. Using this approach, experimental GITT steps could be well fitted and thus validated at different SOC points. This work demonstrates the first usage of the P2D GITT model coupled with optimization as an analytical method to derive and validate physically meaningful parameters. The accurate knowledge of D1 and k as a function of the SOC gives further insight into the SIB intercalation dynamics and rate capability.

Dit artikel is een weergave van de uitgevoerde inventarisatie naar mollusken in het jaar 2019 en 2020 in de Coepelduynen. Het aantal soorten dat door ons is waargenomen tijdens deze inventarisatie is 15. Dit aantal is door de specifieke weersomstandigheden lager dan te verwachten in dit gebied.