"uuid","repository link","title","author","contributor","publication year","abstract","subject topic","language","publication type","publisher","isbn","issn","patent","patent status","bibliographic note","access restriction","embargo date","faculty","department","research group","programme","project","coordinates"
"uuid:dadefdd0-44d8-4202-b9a8-bd75ebb8fc6c","http://resolver.tudelft.nl/uuid:dadefdd0-44d8-4202-b9a8-bd75ebb8fc6c","Assessing the appropriateness of different climate modelling approaches for the estimation of aviation NOx climate effects","Maruhashi, J. (TU Delft Aircraft Noise and Climate Effects); Mertens, Mariano (Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR)); Grewe, V. (TU Delft Aircraft Noise and Climate Effects); Dedoussi, I.C. (TU Delft Aircraft Noise and Climate Effects)","","2023","Aviation’s contribution to anthropogenic global warming is estimated to be between 3 – 5% [1]. This assessment comprises two contributions: the well understood atmospheric impact of carbon dioxide (CO2) and the more uncertain non-CO2 effects. The latter pertain to persistent contrails and pollutants like nitrogen oxides (NOx), water vapor (H2O), sulfur oxides (SOx) and soot particles. NOx emissions are involved in non-linear processes that result in the short-term production of ozone (O3) and longer-term destruction of methane (CH4), stratospheric water vapor (SWV), and primary mode ozone (PMO). The aviation-attributable impacts arising from this short-term increase in O3 can vary by more than a factor of 1.5 depending on the selected modelling approach. This O3 increase is associated with the second largest warming effect across aviation’s main climate forcers [1]. We therefore quantify this figure using three modelling approaches (an Eulerian and a Lagrangian tagging scheme as well as a perturbation approach) at three potential aircraft cruise altitudes (200, 250 and 300 hPa) at which NOx pulse emissions are introduced in the Americas, Africa, Eurasia and Australasia. In general, the tagging method computes the contribution by an emission source to the concentration of a chemical species while a perturbation approach consists in calculating the total impact of an emission to the concentration of a species by means of subtracting two simulations: one with all emissions and a second without the specific source’s emissions. We compare results from Eulerian and Lagrangian simulations using the same climate-chemistry code: the ECHAM5/MESSy Atmospheric Chemistry (EMAC) model. With the Eulerian setup, we are able to capture non-linear processes and feedback effects, but not track the transport of emitted species in detail. The Lagrangian setup [2], on the other hand, allows for the accompaniment of thousands of air parcel trajectories, but at the cost of assuming a simplified linear chemistry mechanism. We find that the Lagrangian tagging approach provides the largest estimates for O3 production and radiative forcing (RF), followed by the Eulerian tagging scheme and lastly by the perturbation method. We therefore investigate the appropriateness of each of these in quantifying aviation’s total and marginal climate effects by addressing the following research questions: 1) By how much are the estimates for the short-term NOx-induced O3 perturbation and consequent RF varying across the three modelling approaches and why? 2) How does this RF vary with emission altitude within the upper Troposphere/lower Stratosphere (UTLS)?
[1] Lee, D.S., Fahey, D.W., Skowron, A., Allen, M.R., Burkhardt, U., Chen, Q., Doherty, S.J., Freeman, S., Forster, P.M., Fuglestvedt, J., Gettelman, A., De León, R.R., Lim, L.L., Lund, M.T., Millar, R.J., Owen, B., Penner, J.E., Pitari, G., Prather, M.J., Sausen, R., and Wilcox, L.J.: The contribution of global aviation to anthropogenic climate forcing for 2000 to 2018, Atmos. Environ., 244, 117834, https://doi.org/10.1016/j.atmosenv.2020.117834, 2021.
[2] Maruhashi, J., Grewe, V., Frömming, C., Jöckel, P., and Dedoussi, I. C.: Transport patterns of global aviation NOx and their short-term O3 radiative forcing – a machine learning approach, Atmos. Chem. Phys., 22, 14253–14282, https://doi.org/10.5194/acp-22-14253-2022, 2022.","Model comparison; NOx-O3 effects; Aviation climate impact","en","abstract","","","","","","","","","","","Aircraft Noise and Climate Effects","","",""
"uuid:936c8190-c287-4c7e-97e6-5338c283b841","http://resolver.tudelft.nl/uuid:936c8190-c287-4c7e-97e6-5338c283b841","Analysis of ESAFORM 2021 cup drawing benchmark of an Al alloy, critical factors for accuracy and efficiency of FE simulations","Habraken, Anne Marie (Katholieke Universiteit Leuven); Aksen, Toros Arda (University of Sakarya); Alves, José L. (University of Minho); Amaral, Rui L. (Universidade do Porto); Chandola, Nitin (University of Florida); Corallo, Luca (Universiteit Gent); Engel, Bernd (University of Siegen); Esener, Emre (Bilecik Seyh Edebali University); Galan Lopez, J. (TU Delft Team Erik Offerman); Kestens, L.A.I. (Universiteit Gent)","","2022","This article details the ESAFORM Benchmark 2021. The deep drawing cup of a 1 mm thick, AA 6016-T4 sheet with a strong cube texture was simulated by 11 teams relying on phenomenological or crystal plasticity approaches, using commercial or self-developed Finite Element (FE) codes, with solid, continuum or classical shell elements and different contact models. The material characterization (tensile tests, biaxial tensile tests, monotonic and reverse shear tests, EBSD measurements) and the cup forming steps were performed with care (redundancy of measurements). The Benchmark organizers identified some constitutive laws but each team could perform its own identification. The methodology to reach material data is systematically described as well as the final data set. The ability of the constitutive law and of the FE model to predict Lankford and yield stress in different directions is verified. Then, the simulation results such as the earing (number and average height and amplitude), the punch force evolution and thickness in the cup wall are evaluated and analysed. The CPU time, the manpower for each step as well as the required tests versus the final prediction accuracy of more than 20 FE simulations are commented. The article aims to guide students and engineers in their choice of a constitutive law (yield locus, hardening law or plasticity approach) and data set used in the identification, without neglecting the other FE features, such as software, explicit or implicit strategy, element type and contact model.","6016-T4 aluminium alloy; Benchmark; Deep drawing modelling; Earing profile prediction; Force prediction; Model comparisons; Thickness prediction","en","journal article","","","","","","","","","","","Team Erik Offerman","","",""
"uuid:3686f988-01e2-4243-a550-5cc31aaeef36","http://resolver.tudelft.nl/uuid:3686f988-01e2-4243-a550-5cc31aaeef36","An inter-model comparison for wave interactions with sea dikes on shallow foreshores","Gruwez, Vincent (Universiteit Gent); Altomare, Corrado (Universitat Politecnica de Catalunya); Suzuki, T. (TU Delft Environmental Fluid Mechanics; Flanders Hydraulics Research; ECOH Corporation); Streicher, Maximilian (Universiteit Gent); Cappietti, Lorenzo (University of Florence); Kortenhaus, Andreas (Universiteit Gent); Troch, Peter (Universiteit Gent)","","2020","Three open source wave models are applied in 2DV to reproduce a large-scale wave flume experiment of bichromatic wave transformations over a steep-sloped dike with a mildly-sloped and very shallow foreshore: (i) the Reynolds-averaged Navier–Stokes equations solver interFoam of OpenFOAM® (OF), (ii) the weakly compressible smoothed particle hydrodynamics model DualSPHysics (DSPH) and (iii) the non-hydrostatic nonlinear shallow water equations model SWASH. An inter-model comparison is performed to determine the (standalone) applicability of the three models for this specific case, which requires the simulation of many processes simultaneously, including wave transformations over the foreshore and wave-structure interactions with the dike, promenade and vertical wall. A qualitative comparison is done based on the time series of the measured quantities along the wave flume, and snapshots of bore interactions on the promenade and impacts on the vertical wall. In addition, model performance and pattern statistics are employed to quantify the model differences. The results show that overall, OF provides the highest model skill, but has the highest computational cost. DSPH is shown to have a reduced model performance, but still comparable to OF and for a lower computational cost. Even though SWASH is a much more simplified model than both OF and DSPH, it is shown to provide very similar results: SWASH exhibits an equal capability to estimate the maximum quasi-static horizontal impact force with the highest computational efficiency, but does have an important model performance decrease compared to OF and DSPH for the force impulse.","Dike-mounted vertical wall; DualSPHysics; Inter-model comparison; OpenFOAM; Shallow foreshore; SWASH; Wave impact loads; Wave modelling","en","journal article","","","","","","","","","","","Environmental Fluid Mechanics","","",""
"uuid:79dbfa08-cebb-4275-b987-85406d21927e","http://resolver.tudelft.nl/uuid:79dbfa08-cebb-4275-b987-85406d21927e","Comparison of Rainfall Products over Sub-Saharan Africa","le Coz, C.M.L. (TU Delft Water Resources); van de Giesen, N.C. (TU Delft Water Resources)","","2019","An ever-increasing number of rainfall estimates is available. They are used in many important applications such as flood/drought monitoring, water management, or climate monitoring. Such data are especially valuable in sub-Saharan Africa, where rainfall has considerable socioeconomic impacts and the gauge and radar networks are sparse. The choice of a rainfall product can significantly influence the performance of such applications. This study reviews previous works, evaluating or comparing rainfall products over different parts of sub-Saharan Africa. Three types of rainfall products are considered: The gauge-only, the satellite-based, and the reanalysis ones. In addition to the global rainfall products, we included three regional ones specifically developed for Africa: The African Rainfall Climatology version 2 (ARC2), the Rainfall Estimate version 2 (RFE2), and the Tropical Applications ofMeteorology Using Satellite Data and Ground-Based Observations (TAMSAT) AfricanRainfall Climatology and Time Series (TARCAT). The gauge density, the orography, and the rainfall regime, which vary with the climate and the season, influence the performance of the rainfall products. This review does not focus on comparing results, as many other publications doing so are already available. Instead, we propose this review as a guide through the different rainfall products available over Africa, and the factors influencing their performances. With this review, the reader can make informed decisions about which products serve their specific purpose best.","Rainfall; Model comparison; Satellite observations; Surface observations","en","journal article","","","","","","","","","","","Water Resources","","",""
"uuid:f8d71242-d02e-4d83-b264-3cd7bf88b0a9","http://resolver.tudelft.nl/uuid:f8d71242-d02e-4d83-b264-3cd7bf88b0a9","Modelling Public Transport On-board Congestion: Comparing Schedule-based and Agent-based Assignment Approaches and their Implications","Cats, O. (TU Delft Transport and Planning); Hartl, Maximilian (University of Stuttgart)","","2016","Transit systems are subject to congestion that influences system performance and level of service. The evaluation of measures to relieve congestion requires models that can capture their network effects and passengers' adaptation. In particular, on-board congestion leads to an increase of crowding discomfort and denied boarding and a decrease in service reliability. This study performs a systematic comparison of alternative approaches to modelling on-board congestion in transit networks. In particular, the congestion-related functionalities of a schedule-based model and an agent-based transit assignment model are investigated, by comparing VISUM and BusMezzo, respectively.
The theoretical background, modelling principles and implementation details of the alternative models are examined and demonstrated by testing various operational scenarios for an example network. The results suggest that differences in modelling passenger arrival process, choice-set generation and route choice model yield systematically different passenger loads. The schedule-based model is insensitive to a uniform increase in demand or decrease in capacity when caused by either vehicle capacity or service frequency reduction. In contrast, nominal travel times increase in the agent-based model as demand increases or capacity decreases. The marginal increase in travel time increases as the network becomes more saturated. Whilst none of the existing models capture the full range of congestion effects and related behavioural responses, existing models can support different planning decisions.