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A Eulerian population balance/Monte Carlo approach for simulating laminar aluminum dust flames

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Particuology 2024年第5期88卷 323-343页

作者： fabian Sewerin Jannis Finke Emmy Noether Group for Dispersed Multiphase Flows Chair of Mechanical Process EngineeringOtto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany

Recently,metal powders have been conceptualized as carbon-free recyclable energy carriers that may form a cornerstone of a sustainable energy *** combustion of metal dusts in oxidizing atmospheres is exothermal and yields oxide particles that could,potentially,be retrieved and,subsequently,recharged by conversion to pure metals using green primary energy *** a step towards a predictive tool for designing metal dust combustors,we present a fully Eulerian modelling approach for laminar particle-laden reactive flows that is,conceptually,based on a population balance description of the dispersed particles and relies on a stochastic Eulerian solution *** the population balance equation(PBE)is formulated for the number-weighted distribution of characteristic properties among all particles near a spatial location,it is kinetically informed by the rates at which mass,momentum and heat are exchanged between the carrier gas and the particulate phase on the single particle *** the scope of the Eulerian Monte Carlo solution scheme,the property distribution is discretely represented in terms of the total number density and a finite number of property samples and the computational work is channelled towards the Eulerian estimation of mean particle *** the case of reactive aluminum particles,we combine a kinetic description of the gas-particle heat and mass transfer with a transport-limited continuum formulation to obtain rate expressions that are valid across the entire particle size range from the free molecular through the continuum *** velocity,the particle properties include only the particle mass,temperature and oxide mass *** set of thermochemical degrees of freedom is retained also as phase transitions due to melting occur,drawing on a smooth blend of the solid and liquid thermodynamic and material *** particle-level formulation encompasses aluminum evaporation,surface oxidation,scavenging of oxi

关键词： Metal dust combustion Aluminum Population balance Eulerian Monte Carlo

Freeform imaging systems:Fermat's principle unlocks"first time right"design

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Light(Science & Applications) 2021年第6期10卷 1029-1040页

作者： fabian Duerr Hugo Thienpont Brussels Photonics Department of Applied Physics and Photonics(B-PHOT TONA)Vrije Universiteit BrusselPleinlaan 21050 BrusselsBelgium

For more than 150 years,scientists have advanced aberration theory to describe,analyze and eliminate imperfections that disturb the imaging quality of optical components and ***,they have developed optical design methods for and manufacturing techniques of imaging systems with ever-increasing complexity and performanee up to the point where they are now including optical elements that are unrestricted in their surface *** so-called optical freeform elements offer degrees of freedom that can greatly extend the functionalities and further boost the specifications of state-of-the-art imaging ***,the drastically increased number of surface coefficients of these freeform surfaces poses severe challenges for the optical design process,such that the deployme nt of freeform optics remained limited until *** this paper,we present a deterministic direct optical design method for freeform imaging systems based on differential equations derived from Fermats principle and solved using power *** method allows calculating the optical surface coefficients that ensure minimal image blurring for each individual order of *** demonstrate the systematic,deterministic,scalable,and holistic character of our method with catoptric and catadioptric design *** such we introduce a disruptive methodology to design optical imaging systems from scratch,we largely reduce the "trial-and-error",approach in present-day optical design,and we pave the way to a fast-track uptake of freeform elements to create the nextgeneratio n high-end *** include a user application that allows users to experience this unique design method hands-on.

关键词： optics eliminate design

Investigation of grain mass flow in a mixed flow dryer

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Particuology 2014年第1期12卷 33-39页

作者： fabian Weigler Jochen Mellmann Department of Post-harvest Technology Leibniz Institute for Agricultural Engineering Potsdam-Bornim

The numerical modeling of grain drying is a topic of great relevance to post-harvest engineering. The required type of drying process depends on the quantity of grain to be dried and the required quality of the grain. The choice of the drying system depends on the operating parameters of the drying process. The granular flow pattern of the material exerts a significant influence on the drying process. Post-harvest drying of grain is essential for better storage, handling, and processing. Therefore, it is important to know the material behavior that controls the particle flow patterns of grain in the drying equipment to guarantee the product quality and to optimize the drying process conditions. The discrete element method （DEM） was applied to investigate the particle flow pattern of wheat through a mixed-flow dryer （MFD） without airflow, and the findings were compared with experimental results in this work. The investigations were performed using dry wheat with 14 wb% moisture content.

关键词： Keywords:Mixed-flow dryerGrain mass flowDiscrete element method

Machine-learning assisted design principle search for singlet fission:an example study of cibalackrot

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npj Computational Materials 2022年第1期8卷 1703-1716页

作者： fabian Weber Hirotoshi Mori Department of Applied Chemistry Chuo University112-8551 Tokyo-toBunkyo-kuKasuga1-13-27Japan Department of Theoretical and Computational Molecular Science Institute for Molecular ScienceOkazaki444-8585Japan

This work uses quantum chemistry calculations and machine learning to explore design rules for singlet fission in a chemical space of four million indigoid *** identify~400,000 derivatives of 2,2′-diethenyl cibalackrot,which theoretically fulfil the energy conditions for exoergic singlet fission above the silicon band gap *** this database with a random forest classifier,we observe that small substituents with positive mesomeric effects and weak negative inductive effects reinforce the desired energetic conditions when placed at specific ***,a subset of molecules that reflects the random forest classifier’s rules are investigated for their quantum chemical properties to translate the desirable structural motifs into wavefunction-based design ***,direct correlations between the energetic condition for singlet fission,the biradical character and the charge and triplet spin density in prominent molecular regions are identified,providing insights that may serve as a guide for singlet fission core structure development.

关键词： singlet quantum classifier

Adaptive nonlinear model predictive control design of a flexible-link manipulator with uncertain parameters

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Acta Mechanica Sinica 2017年第3期33卷 529-542页

作者： fabian Schnelle Peter Eberhard Institute of Engineering and Computational Mechanics University of Stuttgart

This paper presents a novel adaptive nonlinear model predictive control design for trajectory tracking of flexible-link manipulators consisting of feedback linearization, linear model predictive control, and unscented Kalman filtering. Reducing the nonlinear system to a linear system by feedback linearization simplifies the optimization problem of the model predictive controller significantly, which, however, is no longer linear in the presence of parameter uncertainties and can potentially lead to an undesired dynamical behaviour. An unscented Kalman filter is used to approximate the dynamics of the prediction model by an online parameter estimation, which leads to an adaptation of the optimization problem in each time step and thus to a better prediction and an improved input action. Finally, a detailed fuzzy-arithmetic analysis is performed in order to quantify the effect of the uncertainties on the control structure and to derive robustness assessments. The control structure is applied to a serial manipulator with two flexible links containing uncertain model parameters and acting in three-dimensional space.

关键词： Model predictive control Feedback linearization Unscented Kalman filter Flexible-link manipulator Fuzzy-arithmetical analysis

Extreme Cities and Isotropic Territories: Scenarios and Projects Arising from the Environmental Emergency of the Central Veneto Città Diffusa

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International Journal of Disaster Risk Science 2012年第1期3卷 11-22页

作者： Lorenzo fabian Department of Urbanism University IUAV of Venice(Istituto Universitario di Architettura di Venezia)30125 VeniceItaly

In Italy extreme cities and territories occur at the extremities of lagoons,coastlines,and river deltas,in hydraulically reclaimed and hydrogeologically instable areas,and those where the water supply network has been placed underground,channeled into piping,or removed altogether. These areas are now increasingly subject to natural calamities and extreme weather conditions,and the consequences of climate change and the fragility of the more and more impermeable and urbanized land surface are clearly evident. Isotropic territories are characterized by weak hierarchization of infrastructure and settlement. The metropolitan area of Venice,aptly described as a diffuse city(città diffusa),and other diffusely organized territories characterized by settlement dispersion are good examples of this phenomenon. This article reviews recent research at the University IUAV of Venice in a study on climate change and water forms,a project in which the profound relations between water networks,the geological nature of the terrain,forms of urbanization,and energy saving are tested out. The study of the territories of the Venetian metropolitan area provides a series of initial working hypotheses as to how the ongoing environmental emergency can become an opportunity for a development project of the city and the territory,capable of structuring its various parts differently.

关键词： extreme consequences underground

Influence of the number of flights on the dilute phase ratio in flighted rotating drums by PTV measurements and DEM simulations

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Particuology 2021年第3期19卷 171-182页

作者： Lanyue Zhang Zhaochen Jiang Jochen Mellmann fabian Weigler fabian Herz Andreas Bück Evangelos Tsotsas Department of Postharvest Technology Leibniz Institute for Agricultural Engineering and BioeconomyMax-Eyth-Allee 100Potsdam 14469Germany Thermal Process Engineering Otto von Guericke University MagdeburgUniversitaetsplatz 239106 MagdeburgGermany Institute of Particle Technology(LFG) FAU Erlangen-NurembergCauerstr.491058 ErlangenGermany Department of Applied Biosciences and Process Engineering Anhalt University of Applied SciencesBernburgerStr.5506366 KoethenGermany

Particle distribution in the cross-section of the flighted rotating drum(FRD)is critical to the analysis of heat and mass transfer between gas and *** this work,the particle tracking velocimetry(PTV)method is applied to study the influence of the number of flights on the particle motion in *** drum,installed with 1,4,8,or 12 rectangular flights,is filled with plastic balls to 15%and operated at various rotating speeds ranging from 10 rpm to 30 *** results show that the number of flights has different effects on the holdup ratio and cascading rate of single flight and active *** 8 and 12 flights,the FRD produces a larger and more stable particle ratio of the dilute ***,DEM simulations agree with PTV measurements,whereas literature models show significant deviations.

关键词： Flighted rotating drum Number of flights Dilute phase PTV DEM

Simulating orthokinetic heterocoagulation and cluster growth in destabilizing suspensions

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Particuology 2017年第2期15卷 117-128页

作者： fabian Billow Hermann Nirschl Willy Dorfler Institute of Mechanical Process Engineering and Mechanics Karlsruhe Institute of Technology 76131 Karlsruhe Germany Institute for Applied and Numerical Mathematics Karlsruhe Institute of Technology 76131 Karlsruhe Germany

Using direct numerical simulation, we investigate the coagulation behavior of non-Brownian colloidal particles as exemplified by Al2O3 particles. This yields the so-called capture efficiency, for which we give an analytical expression, as well as other time-dependent variables such as the cluster growth rate. Instead of neglecting or strongly approximating the hydrodynamic interactions between particles, we include hydrodynamic and non-hydrodynamic interactions in a Stokesian dynamics approach and a comprehensive modeling of the interparticle forces. The resulting parallelized simulation framework enables us to investigate the dynamics of polydisperse particle systems composed of several hundred particles at the same high level of modeling we used for a close investigation of the coagulation behavior of two unequal particles in shear flow. Appropriate cluster detection yields all the information about large destabilizing systems, which is needed for models used in flow-sheet simulations. After non-dimensionalization, the results can be generalized and applied to other systems tending to secondary coagulation

关键词： Destabilization Coagulation Capture efficiency Al2O3 Cluster detection Stokesian dynamics

Pathogenesis and clinical management of arboviral diseases

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World Journal of Virology 2025年第1期14卷 9-50页

作者： Victoria Cenci Dietrich Juan Marcos Caram Costa Marina Maria Gomes Leite Oliveira Carlos Eduardo Oliveira Aguiar Luis Guilherme de Oliveira Silva Marcel Silva Luz fabian Fellipe Bueno Lemos Fabrício Freire de Melo Instituto Multidisciplinar em Saúde Universidade Federal da BahiaVitória da Conquista 45029-094BahiaBrazil

Arboviral diseases are viral infections transmitted to humans through the bites of arthropods,such as mosquitoes,often causing a variety of pathologies associated with high levels of morbidity and *** the past decades,these infections have proven to be a significant challenge to health systems worldwide,particularly following the considerable geographic expansion of the dengue virus(DENV)and its most recent outbreak in Latin America as well as the difficult-tocontrol outbreaks of yellow fever virus(YFV),chikungunya virus(CHIKV),and Zika virus(ZIKV),leaving behind a substantial portion of the population with complications related to these ***,the world is experiencing a period of intense globalization,which,combined with global warming,directly contributes to wider dissemination of arbovirus vectors across the ***,all continents remain on high alert for potential new ***,this review aims to provide a comprehensive understanding of the pathogenesis of the four main arboviruses today(DENV,ZIKV,YFV,and CHIKV)discussing their viral characteristics,immune responses,and mechanisms of viral evasion,as well as important clinical aspects for patient *** includes associated symptoms,laboratory tests,treatments,existing or developing vaccines and the main associated complications,thus integrating a broad historical,scientific and clinical approach.

关键词： Arboviruses Arbovirus infections Dengue Zika virus Yellow fever Chikungunya virus Clinical diagnosis Pathogenesis Flavivirus Togaviridae infections