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Investigating the inflow into a granular bed using a locally resolved method

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Particuology 2024年第2期85卷 89-101页

作者： maximilian Brommer Maik Scharnowski Enric Illana Mahiques Siegmar Wirtz Viktor Scherer Ruhr University Bochum Institute of Energy Plant TechnologyUniversitätsstraβe 15044780BochumGermany

Discrete Element Method-Computational Fluid Dynamics(DEM/CFD)simulations of industrial-scale granular systems employ spatial averaging(porous media approach)for the fluid-particle interaction in the whole domain,which can lead to poor accuracy,for instance at flow inlets,as local particle bulk morphology is not *** paper presents an approach where the interstitial flow in crucial areas with large gradients can be resolved locally in an otherwise unresolved domain,so that a mixed resolved-unresolved method is *** a generic example to show the feasibility and performance of the new approach,the inflow of ambient air into a flat-bottom hopper through a narrow orifice is *** an experimental setup,the vertical profile of the pressure decay through the inlet and across the packing is chosen for com-parison with respective *** obtained with the conventional porous media method and the locally resolved approach are compared to these experiments for varying volume flow rates and for two different particle *** of different size as well as dodecahedrons are *** is found that although averaging methods already provide good approximations,the locally resolved method can improve the result especially when conventional drag laws are not applicable due to wall effects or if large velocity gradients exist.

关键词： DEM/CFD Packed bed Pressure drop

Shape-changing particles for locally resolved particle geometry in DEM simulations

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Particuology 2024年第6期89卷 185-190页

作者： Enric Illana Klidi Qyteti Maik Scharnowski maximilian Brömmer Siegmar Wirtz Viktor Scherer Institute of Energy Plant Technology Ruhr-University BochumBochumGermany

Taking into account the complex shape of particles in discrete element method (DEM) simulations of large-scale granular systems is computationally demanding due to the time-consuming contact detection algorithms for polyhedral particles. In this short communication, a novel approach that locally resolves the particle shapes where needed and uses a simplified representation elsewhere, to accelerate simulations without compromising accuracy, is presented. For this purpose, a method employing a smooth transition of the particle shape representation from analytical spheres to shape-resolving polyhedra is introduced in DEM. The feasibility and correct implementation of this approach are demonstrated through simulations of hopper discharge involving spherical and dodecahedral particles from a flat bottom silo or shaft kiln. The model capabilities, in terms of accuracy as well as reduction in computational effort, are quantified for a moving bed with continuous outflow.

关键词： Polyhedron Size change Shape change Locally resolved DEM

Ab initio density response and local field factor of warm dense hydrogen

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Matter and Radiation at Extremes 2024年第5期9卷 48-67页

作者： Tobias Dornheim Sebastian Schwalbe Panagiotis Tolias maximilian P.Böhme Zhandos A.Moldabekov Jan Vorberger Center for Advanced Systems Understanding(CASUS) D-02826 GörlitzGermany Helmholtz-Zentrum Dresden-Rossendorf(HZDR) D-01328 DresdenGermany Space and Plasma Physics Royal Institute of Technology(KTH)Stockholm SE-10044Sweden Technische Universität Dresden D-01062 DresdenGermany

We present quasi-exact ab initio path integral Monte Carlo(PIMC)results for the partial static density responses and local field factors of hydrogen in the warm dense matter regime,from solid density conditions to the strongly compressed *** full dynamic treatment of electrons and protons on the same footing allows us to rigorously quantify both electronic and ionic exchange–correlation effects in the system,and to compare the results with those of earlier incomplete models such as the archetypal uniform electron gas or electrons in a fixed ion snapshot potential that do not take into account the interplay between the two *** full electronic density response is highly sensitive to electronic localization around the ions,and our results constitute unambiguous predictions for upcoming X-ray Thomson scattering experiments with hydrogen jets and fusion *** PIMC results are made freely available and can be used directly for a gamut of applications,including inertial confinement fusion calculations and the modeling of dense astrophysical ***,they constitute invaluable benchmark data for approximate but computationally less demanding approaches such as density functional theory or PIMC within the fixed-node approximation.

关键词： local incomplete rigorous

Explainability and Interpretability in Electric Load Forecasting Using Machine Learning Techniques–A Review

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Energy and AI 2024年第2期16卷 483-496页

作者： Lukas Baur Konstantin Ditschuneit maximilian Schambach Can Kaymakci Thomas Wollmann Alexander Sauer Fraunhofer Institute for Manufacturing Engineering and Automation IPA Nobelstraße 12Stuttgart70569Germany Institute for Energy Efficiency in Production(EEP) University of StuttgartNobelstraße 12Stuttgart70569Germany Merantix Momentum GmbH Max-Urich-Straße 3Berlin13355Germany

Electric Load Forecasting(ELF)is the central instrument for planning and controlling demand response programs,electricity trading,and consumption *** to the increasing automation of these processes,meaningful and transparent forecasts become more and more ***,at the same time,the complexity of the used machine learning models and architectures *** there is an increasing interest in interpretable and explainable load forecasting methods,this work conducts a literature review to present already applied approaches regarding explainability and interpretability for load forecasts using Machine *** on extensive literature research covering eight publication portals,recurring modeling approaches,trends,and modeling techniques are identified and clustered by properties to achieve more interpretable and explainable load *** results on interpretability show an increase in the use of probabilistic models,methods for time series decomposition and the use of fuzzy logic in addition to classically interpretable *** explainable approaches are Feature Importance and Attention *** discussion shows that a lot of knowledge from the related field of time series forecasting still needs to be adapted to the problems in *** to other applications of explainable and interpretable methods such as clustering,there are currently relatively few research results,but with an increasing trend.

关键词： Electric load forecasting Explainability InterpretabilityStructured review

Comparing two IBM implementations for the simulation of uniform packed beds

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Particuology 2024年第3期86卷 1-12页

作者： Christian Gorges maximilian Brommer Christin Velten Siegmar Wirtz Enric Illana Mahiques Viktor Scherer Katharina Zahringer Berend van Wachem Mechanical Process Engineering Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany Department of Energy Plant Technology Ruhr-Universitat BochumUniversitatsstraBe 15044780BochumGermany Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universitat MagdeburgUniversitatsplatz 239106MagdeburgGermany

Nowadays,the design of fixed packed bed reactors still relies on empirical correlations,which,especially for small tube to particle diameter ratios,are mostly too inaccurate because of the presence of wall ***,the simulation of fixed packed bed reactors plays an important role to predict and control the flow and process parameters in such,nowadays and in the *** of its straightforward applicability to non-uniform packings with particles of arbitrary shapes,the immersed boundary method(IBM)has advantages over other numerical methods and is used more and more *** paper compares two approaches of IBMs for the simulation of fixed bed reactors with spherical shaped *** classic,smooth approach is compared to the straightforward to implement blocked-off method for velocity fields above the fixed bed for particle Reynolds numbers of 300 and *** from experimental inline PIV-measurements of the reactor to be simulated serve as a basis for *** good agreement with the experiment is found for both simulation methodologies with higher resolutions,considering the more stable flow at a particle Reynolds number of *** in the different IBM approaches occurred for the more unsteady flow at a particle Reynolds number of *** to the blocked-off method,the smooth IBM reflects the formation of additional jets and recirculation zones better right above the bed,though increasing the fluid mesh resolution improves the accuracy of the blocked-off ***,a more diffusive behaviour is found for the blocked-off simulations due to the stairstep representation,which is avoided by using interpolation stencils as in the smooth *** higher mesh refinement in the blocked-off IBM this effect can be reduced,but this also increases the computational effort.

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

Determinant variables on the isotopic values of particulate organic matter in a neotropical floodplain

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Journal of Oceanology and Limnology 2024年第4期42卷 1173-1185页

作者： Vinícius de ANDRADE URBANO Matheus maximilian RATZ SCOARIZE Gustavo HENRIQUE ZAIA ALVES Driele DELANIRA-SANTOS Marcela da SILVA CAETANO Evanilde BENEDITO Departamento de Biologia(DBI) Laboratório de Ecologia EnergéticaUniversidade Estadual de Maringá(UEM)Maringá87020-900Brasil Programa de Pós-graduação em Ecologia de Ambientes Aquáticos Continentais(PEA) Universidade Estadual de Maringá(UEM)Maringá87020-900Brasil Departamento de Biologia Geral Universidade Estadual de Ponta Grossa(UEPG)Campus UvaranasPonta Grossa 84030-900Brasil Australian Rivers Institute(ARI) Griffith UniversityNathan QLD 4111Australia

Particulate organic matter(POM)is an important energy source for aquatic consumers,understanding its origin and composition is essential for understanding the energetic dynamics of aquatic *** aim of this study was to analyze the relationship between POM and phytoplankton(isotopic values and chlorophyll concentration)and abiotic variables during dry and rainy *** was conducted in rivers and lagoons in the floodplain of the Upper Paraná*** found a greater difference in ^(δ13)C values of POM between sampling points than between seasons,indicating that the composition of regional sources influences the composition of POM more than dry and rainy *** addition,the concentration of chlorophyll during the dry season was positively correlated with ^(δ13)C values during that rainy ***,we found a relationship between factors limiting the growth of phytoplankton and ^(δ13)C values of POM,such as phosphate ions,indicating that variables that regulate phytoplankton growth tend to influence the composition of POM in river ***,maintaining the variables that regulate the phytoplankton community is of fundamental importance for the composition of POM,an important energy source in aquatic environments.

关键词： freshwater wetland stable isotopes food web subtropical environment

Beyond total mesorectal excision: The emerging role of minimally invasive surgery for locally advanced rectal cancer

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World Journal of Gastrointestinal Surgery 2024年第8期16卷 2382-2385页

作者： Davina Perini Francesca Cammelli maximilian Scheiterle Jacopo Martellucci Annamaria Di Bella Carlo Bergamini Paolo Prosperi Alessio Giordano Department of Emergency and Acceptance Emergency Surgery UnitCareggi University HospitalFirenze 50137Italy

Multivisceral resection and/or pelvic exenteration represents the only potential curative treatment for locally advanced rectal cancer(LARC);however,it poses significant technical challenges,which account for the high risk of morbidity and mortality associated with the *** complete histopathologic resection is the most important determinant of patient outcomes,LARC often requires an extended resection beyond the total mesorectal excision plane to obtain clear re-section *** an era when laparoscopic surgery and robot-assisted surgery are becoming commonplace,the optimal approach to extensive pelvic inter-ventions remains ***,acceptance of the suitability of mini-mally invasive surgery is slowly gaining ***,there is still a lack of evidence in the literature about minimally invasive approaches in multiple and extensive surgical resections,highlighting the need for research studies to explore,validate,and develop this *** editorial aims to provide a critical overview of the currently available applications and challenges of minimally invasive abdo-minopelvic surgery for ***,we discuss recent developments in the field of robotic surgery for LARC,with a specific focus on new innovations and emerging frontiers.

关键词： Robotic surgery Pelvic exenteration Multivisceral resection Rectal cancer Total mesorectal excision

Statistical Models for Condition Monitoring and State of Health Estimation of Lithium-Ion Batteries for Ships

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Journal of Dynamics, Monitoring and Diagnostics 2024年第1期3卷 11-20页

作者： Erik Vanem Qin Liang maximilian Bruch Gjermund Bøthun Katrine Bruvik Kristian Thorbjørnsen Azzeddine Bakdi DNV GRD HøvikNorway Department of Mathematics University of OsloOsloNorway Fraunhofer ISE FreiburgGermany Corvus Energy BergenNorway Corvus Energy PorsgrunnNorway

Battery systems are increasingly being used for powering ocean going ships,and the number of fully electric or hybrid ships relying on battery power for propulsion is *** ensure the safety of such ships,it is important to monitor the available energy that can be stored in the batteries,and classification societies typically require the state of health(SOH)to be verified by independent *** paper addresses statistical modeling of SOH for maritime lithium-ion batteries based on operational sensor *** methods for sensor-based,data-driven degradation monitoring will be presented,and advantages and challenges with the different approaches will be *** different approaches include cumulative degradation models and snapshot models,models that need to be trained and models that need no prior training,and pure data-driven models and physics-informed *** of the methods only rely on measured data,such as current,voltage,and temperature,whereas others rely on derived quantities such as state of *** include simple statistical models and more complicated machine learning *** from this exploration will be important in establishing a framework for data-driven diagnostics and prognostics of maritime battery systems within the scope of classification societies.

关键词： battery condition monitoring data-driven analytics diagnostics state of health

Improving cycling performance of the NaNiO_(2)cathode in sodium-ion batteries by titanium substitution

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Materials Futures 2024年第3期3卷 132-147页

作者： Siyu An Leonhard Karger Sören L Dreyer Yang Hu Eduardo Barbosa Ruizhuo Zhang Jing Lin maximilian Fichtner Aleksandr Kondrakov Jürgen Janek Torsten Brezesinski Battery and Electrochemistry Laboratory(BELLA) Institute of NanotechnologyKarlsruhe Institute of Technology(KIT)Kaiserstr.1276131 KarlsruheGermany Helmholtz Institute Ulm(HIU)Electrochemical Energy Storage Helmholtzstr.1189081 UlmGermany BASF SE Carl-Bosch-Str.3867056 LudwigshafenGermany Institute of Physical Chemistry&Center for Materials Research(ZfM/LaMa) Justus-Liebig-University GiessenHeinrich-Buff-Ring 1735392 GiessenGermany

O3-type layered oxide cathodes,such as NaNi_(0.5)Mn_(0.5)O_(2),have garnered significant attention due to their high theoretical specific capacity while using abundant and low-cost sodium as intercalation *** the lithium analog(LiNiO_(2)),NaNiO_(2)(NNO)exhibits poor electrochemical performance resulting from structural instability and inferior Coulomb *** enhance its cyclability for practical application,NNO was modified by titanium substitution to yield the O3-type NaNi_(0.9)Ti_(0.1)O_(2)(NNTO),which was successfully synthesized for the first time via a solid-state *** mechanism behind its superior performance in comparison to that of similar materials is examined in detail using a variety of characterization *** delivers a specific discharge capacity of∼190 mAh g^(−1)and exhibits good reversibility,even in the presence of multiple phase transitions during cycling in a potential window of 2.0−4.2 V ***^(+)/*** behavior can be attributed to the substituent,which helps maintain a larger interslab distance in the Na-deficient phases and to mitigate Jahn–Teller activity by reducing the average oxidation state of ***,volume collapse at high potentials and irreversible lattice oxygen loss are still detrimental to the ***,the performance can be further enhanced through coating and doping *** not only positions NNTO as a promising next-generation cathode material,but also serves as inspiration for future research directions in the field of high-energy-density Na-ion batteries.

关键词： Ni-rich layered oxide cathode material substitution doping electro-chemo-mechanical degradation Na-ion battery