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An approach for finding causal relations in environmental systems:with an application to understand drivers of a toxic algal bloom

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Ecological Processes 2024年第1期13卷 108-119页

作者： Benny Selle Berliner Hochschule Für technik Fachbereich Geowissenschaften Universit?t Tübingen

Background Discovering causality in environmental systems is challenging because frequently controlled experiments or numerical simulations are difficult. Algorithms to learn directed acyclic graphs from system data are powerful, but they often result in too many possible causal structures that cannot be properly *** An approach to this problem proposed here is to initially restrict the system to a target variable with its two major drivers. Subsequently, testable causal structures are obtained from rules to infer directed acyclic graphs and expert knowledge. the proposed approach, which is essentially based on correlation and regression, was applied to understand drivers of a toxic algal bloom in the Odra River in summer 2022. through this application, useful insight on the interplay between river flow and salt inputs that likely caused the algal bloom was *** the Odra River example demonstrated that carefully applied correlation and regression techniques together with expert knowledge can help to discover reliable casual structures in environmental systems.

关键词： Causal effect Causal model Causal diagram Mediation analysis Directed acyclic graph Classification and regression trees

Convective drying of wood chips:Accelerating coupled DEM-CFD simulations with parametrized reduced single particle models

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Particuology 2024年第1期84卷 158-167页

作者： Lucas Reineking Jonas Fischer Ali Mjalled Enric Illana Siegmar Wirtz Viktor Scherer Martin Monnigmann Automatic Control and System theory Ruhr-Universität-BochumUniversitätstraße 150Bochum44801Germany Energy Plant technology Ruhr-Universität-BochumUniversitätstraße 150Bochum44801Germany

the simulation of industry-scale reactive bulks is challenging due to the complex interaction between fluid and *** particles in the bulk and their interaction with the fluid flow can be described by combined Discrete Element Method-Computational Fluid Dynamics(DEM-CFD)***,the computational cost of the Finite Volume(FV)methods deployed in these models can become prohibi-tively expensive,especially for high inner-particle *** particle Reduced Models(RMs)can be used to achieve both fast and accurate descriptions of the processes in each *** an example of bulk systems comprising heat and mass transfer,we compared FV and RM simulations for the drying of wood chips in a bulk reactor.A manifold-based nonlinear interpolation was applied to resolve changing boundary conditions for the *** simulations showed that RMs provide accurate values for the thermodynamic state variables of the ***,the time required for the bulk simulation was reduced by 67%with the *** is evident that simulations with high inner-particle resolution can be accelerated by RMs if manifold-based nonlinear interpolation is used to address changing boundary conditions.

关键词： Reduced model Reactive bulk Discrete element method Manifold-based interpolation Drying of porous mediaDEM-CFD

Experimental and numerical investigation to elucidate the fluid flow through packed beds with structured particle packings

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Particuology 2024年第6期89卷 218-237页

作者： Shirin Patil Christian Gorges Joel Lòpez Bonilla Moritz Stelter Frank Beyrau Berend van Wachem Laboratory of technical thermodynamics Otto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany Chair of Mechanical Process Engineering Otto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany

the present paper presents an experimental and numerical investigation of the dispersion of the gaseous jet flow and co-flow for the simple unit cell(SUC)and body-centred cubic(BCC)configuration of particles in packed *** experimental setup is built in such a way that suitable and simplified boundary conditions are imposed for the corresponding numerical framework,so the simulations can be done under very similar conditions as the ***,a porous plate is used for the co-flow to achieve the uniform velocity and the fully developed flow is ensured for the jet *** SUC and BCC particle beds consist of 3D-printed spheres,and the non-isotropy near the walls is mostly eliminated by placing half-spheres at the channel *** flow velocities are analysed directly at the exit of the particle bed for both beds over 36 pores for the SUC configuration and 60 pores for the BCC configuration,for particle Reynolds numbers of 200,300,and *** particle image velocimetry is experimentally arranged in such a way that the velocities over the entire region at the exit of the packed bed are obtained *** numerical method consists of a state-of-the-art immersed boundary method with adaptive mesh *** paper presents the pore jet structure and velocity field exiting from each pore for the SUC and BCC packed particle *** numerical and experimental studies show a good agreement for the SUC configuration for all flow *** the BCC configuration,some differences can be observed in the pore jet flow structure between the simulations and the experiments,but the general flow velocity distribution shows a good overall *** axial velocity is generally higher for the pores located near the centre of the packed bed than for the pores near the *** addition,the axial velocities are observed to increase near the peripheral pores of the packed *** behaviour is predominant for the BCC configuration as compared to t

关键词： Uniform particle packing Packed bed reactor Stereo particle image velocimetry Immersed boundary method

Approximate contact solutions for non-axisymmetric homogeneous and power-law graded elastic bodies:A practical tool for design engineers and tribologists

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Friction 2024年第2期12卷 340-355页

作者： Valentin L.POPOV Qiang LI Emanuel WILLERt Institute of Mechanics Technische Universität BerlinBerlin 10623Germany

In two recent papers,approximate solutions for compact non-axisymmetric contact problems of homogeneous and power-law graded elastic bodies have been suggested,which provide explicit analytical relations for the force–approach relation,the size and the shape of the contact area,as well as for the pressure distribution *** solutions were derived for profiles,which only slightly deviate from the axisymmetric *** the present paper,they undergo an extensive testing and validation by comparison of solutions with a great variety of profile shapes with numerical solutions obtained by the fast Fourier transform(FFt)-assisted boundary element method(BEM).Examples are given with quite significant deviations from axial symmetry and show surprisingly good agreement with numerical solutions.

关键词： normal contact non-axisymmetric indenter extremal principle generalized method of dimensionality reduction(MDR) functional elastic grading

A simulation study on spatial and time resolution for a cost-effective positron emission particle tracking system

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Particuology 2024年第5期88卷 312-322页

作者： Josephine Oppotsch Matthias Steinke Miriam Fritsch Fritz-Herbert Heinsius thomas Held Nikoline Hilse Viktor Scherer Ulrich Wiedner Ruhr-universität Bochum Institut für Experimentalphysik I44801 BochumGermany Ruhr-universität Bochum Lehrstuhl für Energieanlagen und Energieprozesstechnik44801 BochumGermany

this work is the second part of a simulation study investigating the processing of densely packed and moving granular assemblies by positron emission particle tracking (PEPt).Since medical positron emission tomography (PEt) scanners commonly used for PEPt are very expensive,a PEt-like detector system based on cost-effective organic plastic scintillator bars is being developed and tested for its *** this context,the spatial resolution of a resting positron source,a source moving on a freely designed model path,and a particle motion given by a discrete element method (DEM) simulation is studied using Monte Carlo simulations and the software toolkit *** not only extended the simulation and reconstruction to a moving source but also significantly improved the spatial resolution compared to previous work by adding oversampling and iteration to the reconstruction ***,in the case of a source following a trajectory developed from DEM simulations,a very good resolution of about 1 mm in all three directions and an average 3D deviation between simulated and reconstructed events of 2.3 mm could be ***,the resolution for realistic particle motion within the generic grate system (which is the test rig for further experimental studies) is well below the smallest particle *** simulation of the dependence of the reconstruction accuracy on tracer particle location revealed a nearly constant efficiency within the entire detector system,which demonstrates that boundary effects can be neglected.

关键词： Positron emission particle tracking Monte Carlo method time-of-flight Plastic scintillators Silicon photomultipliers(SiPMs)

A simulation study for a cost-effective PEt-like detector system intended to track particles in granular assemblies

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Particuology 2024年第1期84卷 117-125页

作者： Josephine Oppotsch Antonios Athanassiadis Miriam Fritsch Fritz-Herbert Heinsius thomas Held Nikoline Hilse Viktor Scherer Matthias Steinke Ulrich Wiedner Ruhr-universität Bochum Institut für Experimentalphysik I44801 BochumGermany Ruhr-universität Bochum Lehrstuhl für Energieanlagen und Energieprozesstechnik44801 BochumGermany

Since many industrial applications rely on the processing of densely packed and moving granular ma-terial,obtaining bulk internal information on the particle movement inside the reactors is of great *** information can be delivered by Positron Emission Particle tracking(PEPt).By marking pellets with a positron-emitting radioisotope,the position of these tracer particles can be determined via the time-of-flight differences of the emitted gamma-ray *** current paper proposes a PEt-like detector system based on cost-effective organic plastic scintillators instead of the more common but expensive inorganic *** system is currently under construction and was tested for its resolution and efficiency in this simulation *** Monte Carlo simulations and the software toolkit Geant4,three different geometries(an empty glass box,a generic grate system,and a cubic box of 1 m3 completely filled with pellets)were investigated,leading to a spatial resolution in the millimeter range and an efficiency,defined as the ratio of reconstructed decay locations to simulated decays,of 2.7%,1.4%,and 0.3%.

关键词： Positron emission particle tracking Geant4 Monte Carlo method time-of-flight Plastic scintillators Silicon photomultipliers(SiPMs)

Data-driven analysis of chemicals,proteins and pathways associated with peanut allergy:from molecular networking to biological interpretation

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Food Science and Human Wellness 2024年第3期13卷 1322-1335页

作者： Emmanuel Kemmler Julian Braun Florent Fauchère Sabine Dölle-Bierke Kirsten Beyer Robert Preissner Margitta Worm Priyanka Banerjee Institute for Physiology Charité-University Medicine BerlinBerlin 10115Germany Member of the KFO339 FOOD@Berlin 10115Germany Si-M/“Der Simulierte Mensch”a science framework of technische universität Berlin and Charité-universitätsmedizin Berlin Berlin 10115Germany Charité-universitätsmedizin Berlin corporate member of Freie Universität BerlinHumboldt-Universität zu Berlinand Berlin Institute of HealthBerlin 10115Germany Division of Allergy and Immunology Department of DermatologyVenerology and AllergyCharité-Universitätsmedizin Berlincorporate member of Freie Universität Berlin and Humboldt-Universität zu BerlinBerlin 10115Germany Pediatrics Campus VirchowCharité-University Medicine BerlinBerlin 10115Germany

Peanut allergy is majorly related to severe food induced allergic *** food including cow's milk,hen's eggs,soy,wheat,peanuts,tree nuts(walnuts,hazelnuts,almonds,cashews,pecans and pistachios),fish and shellfish are responsible for more than 90%of food ***,we provide promising insights using a large-scale data-driven analysis,comparing the mechanistic feature and biological relevance of different ingredients presents in peanuts,tree nuts(walnuts,almonds,cashews,pecans and pistachios)and ***,we have analysed the chemical compositions of peanuts in different processed form raw,boiled and *** the data-driven approach we are able to generate new hypotheses to explain why nuclear receptors like the peroxisome proliferator-activated receptors(PPARs)and its isoform and their interaction with dietary lipids may have significant effect on allergic *** results obtained from this study will direct future experimeantal and clinical studies to understand the role of dietary lipids and PPARisoforms to exert pro-inflammatory or anti-inflammatory functions on cells of the innate immunity and influence antigen presentation to the cells of the adaptive immunity.

关键词： Allergy informatics Knowledge-graph Data analysis Food allergy Peroxisome proliferator-activated receptors Fatty acids

Enhancing wood efficiency through comprehensive wood flow analysis:Methodology and strategic insights

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Forest Ecosystems 2024年第2期11卷 172-183页

作者： Ruisheng Wang Peer Haller Institute of Steel and timber Construction Technische Universität Dresden01062DresdenGermany

Wood,an essential natural resource in human civilization,remains widely used despite advances in technology and material *** surge in greenhouse gas emissions and environmental concerns accentuates the need for optimizing wood *** flow analysis is a powerful tool for tracking material flows and stocks,aiding resource management and environmental ***,the full extent of its methodological dimensions,particularly within the context of the wood supply chain,remains relatively *** this study,we delve into the existing literature on wood flow analysis,discussing its primary objectives,materials involved,temporal and spatial scales,data sources,units,and conversion ***,data uncertainty,data reconciliation and crucial assumptions in material flow analysis are highlighted in this *** findings reveal the significance of wood cascading and substitution effects by replacing non-wood materials,where they can reduce greenhouse gas emissions more than the natural carbon sink of forests and wood *** immediate impact of short-term wood cascading might not be as robust as the substitution effect,with energy substitution showcasing better results than material ***,it's crucial to note that these conclusions could experience significant reversal from a long-term and global *** for improving wood efficiency involve maximizing material use,advancing construction technologies,extending product lifespans,promoting cascade use,and optimizing energy recovery *** study underscores the need for standardized approaches in wood flow analysis and emphasizes the potential of wood efficiency strategies in addressing environmental challenges.

关键词： Material flow analysis Wood Methodology Cascade use Substitution effects

Ray tracing particle image velocimetry-Challenges in the application to a packed bed

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Particuology 2024年第1期84卷 194-208页

作者： Christin Velten Mirko Ebert Christian Lessig Katharina Zahringer Lehrstuhl für Strömungsmechanik und Strömungstechnik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany Institut für Simulation und Graphik Otto-von-Guericke-Universität Magdeburg39106MagdeburgGermany

Ray tracing Particle Image Velocimetry(Rt-PIV)is an optical technique for high resolution velocity measurements in challenging optical systems,such as transparent packed beds,that uses ray tracing to correct for distortions introduced by transparent geometries in the light *** ray tracing based correction is a post processing step applied to the raw PIV particle images before classical PIV *** this study,Rt-PIV is performed in the top layer of a body centred cubic(bcc)sphere packing with gaseous flow,where optical access is obtained by the use of transparent N-BK7 glass balls with a diameter of d=40 ***-PIV introduces new experimental and numerical challenges,for example a limited field of view,illumination difficulties,a very large required depth of field and high sensitivity to geometric parameters used in the ray tracing *** challenges and their implications are the main scope and discussed in the present ***,the validation of the ray tracing reconstruction step is presented and examples for the obtained corrected vector fields in a packed bed are *** results show the strength of the method in reconstructing velocity fields behind transparent spheres that would not have been accessible by optical measurement techniques without the ray tracing correction.

关键词： Ray tracing particle image velocimetry(Rt-PIV) transparent spherical particles Packed bed Distortion correction Gas flow