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Particuology 2014年第1期12卷 44-53页

作者： Guang Lu James r.Third christoph r.müller ETH Zürich Department of Mechanical and Process Engineering Institute of Energy Technology Laboratory of Energy Science and Engineering8092 Zürich Switzerland

Discrete-element-method （DEm） simulations have been performed to investigate the cross-sectional flow of non-spherical particles in horizontal rotating cylinders with and without wall rougheners. The non-spherical particles were modeled using the three-dimensional super-quadric equation. The influence of wall rougheners on flow behavior of grains was studied for increasing particle blockiness. moreover, for approximately cubic particles （squareness par.meters [555]）, the rotational speed, gravitational acceleration and particle size were altered to investigate the effect of wall rougheners under a range of operating conditions. For spherical and near-spherical particles （approximately up to the squareness par.meters [344]）, wall rougheners are necessary to prevent slippage of the bed against the cylinder wall. For highly cubic particle geometries （squareness par.meters larger than [3441）, wall rougheners resulted in a counter-intuitive decrease in the angle of repose of the bed. In addition, wall rougheners employed in this study were demonstrated to have a higher impact on bed dynamics at higher rotational speeds and lower gravitational accelerations. Nevertheless, using wall rougheners had a comparatively small influence on particle-flow characteristics for a bed composed of finer grains.

关键词： Granular flowNon-spherical particlesrotating cylinderDiscrete element method (DEm)Kiln

Validation of a discrete element model using magnetic resonance measur.ments

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Particuology 2009年第4期7卷 297-306页

作者： christoph r.müller Stuart A.Scott Daniel J.Holland Belinda C.Clarke Andrew J.Sederman John S.Dennis Lynn F.Gladden Depar.ment of Chemical Engineering and Biotechnology University of CambridgePembroke StreetCambridge CB2 3RAUnited Kingdom

The discrete element model （DEm） is a very pr.mising modelling strategy for two-phase granular systems. However, owing to a lack of exper.mental measur.ments, validation of numerical simulations of two-phase granular systems is still an important issue. In this study, a small two-dimensional gas- fluidized bed was simulated using a discrete element model. The dimensions of the simulated bed were 44mm × 10mm × 120 mm and the fluidized particles had a diameter dp = 1.2 mm and density ρp = 1000 kg/m^3. The comparison between DEm simulations and exper.ments are performed on the basis of time-averaged voidage maps. The drag-law of Beetstra et al. [Beetstra, r., van der Hoef, m.A., ＆ Kuipers,J. A. m. （2007b）. Drag force of intermediate reynolds number flow past mono- and bidispersed arrays of spheres. AIChE Journal, 53,489-501 ] seems to give the best results. The simulations are fairly insensitive to the coefficient of restitution and the coefficient of friction as long as some route of energy dissipation during particle-particle and particle-wall contact is provided. Changing the boundary condition of the gas phase at the side-walls fr.m zero-slip to full-slip does not affect the simulation results. Care is to be taken that the cell sizes are chosen so that a reasonable number of particles can be found in a fluid cell.

关键词： Discrete element modelling magnetic resonance imaging Voidage Gas-fluidized beds

magnetic resonance studies of a gas-solids fluidised bed:Jet-jet and jet-wall interactions

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Particuology 2010年第6期8卷 617-622页

作者： meenal Pore Daniel J.Holland Thusara C.Chandrasekera christoph r.müller Andrew J.Sederman John S.Dennis Lynn F.Gladden John F.Davidson Depar.ment of Chemical Engineering and Biotechnology University of CambridgePembroke StreetCambridgeCB2 3RAUK Depar.ment of mechanical and Process Engineering ETH ZurichSonneggstrasse 38092 ZurichSwitzerland

magnetic resonance imaging （mrI） gave images of air jets fr.m orifices in the distributor plate of a bed of poppy seeds. Attention focused on two features：（1） The interaction between nearby vertical jets fr.m two, three or four orifices; （2） Wall effects, where one or.more orifices created vertical jets near the vertical wall of the cylinder containing the particle bed. The results show that nearby jets are mutually attracted. Likewise a jet near a wall bends out of the vertical, towards the wall, For.multiple adjacent jets, the jet lengths show dependence on orifice layout： the lengths are in reasonable agreement with published measur.ments, by other.methods, for single jets. The mrI gives three-dimensional images of the single jets and of multiple jets, separate or.merging.

关键词： Fluidised bed mrI Jets Distributor design

Sol-gel derived B_(2)O_(3)-CaO borate bioactive glasses with hemostatic,antibacterial and pro-angiogenic activities

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regenerative Biomaterials 2024年第1期3卷 108-118页

作者： Kai Zheng Faina Bider.mahshid monavari Zhiyan Xu Christina Janko christoph Alexiou Ana m.Beltran Aldo r.Boccaccini Jiangsu Province Engineering research Center of Stomatological Translational medicine College of StomatologyNanjing Medical UniversityNanjing 210029China Jiangsu Key Laboratory of Oral Diseases Nanjing Medical UniversityNanjing 210029China Institute of Biomaterials University of Erlangen-Nuremberg91058 ErlangenGermany Depar.ment of Oto-rhino-Laryngology Head and Neck SurgerySection of Experimental Oncology and Nanomedicine(SEON)Else Kroener-Fresenius-Stiftung ProfessorshipUniversitaetsklinikum Erlangen91058 ErlangenGermany Departamento de Ingenier�ıa y Ciencia de los materiales y del Transporte Escuela Politecnica

Sol-gel borate bioactive glasses(BGs)are pr.mising ion-releasing biomaterials for wound healing ***,we report the synthesis of a series of binary B_(2)O_(3)-CaO borate BGs(CaO ranging fr.m 50 to 90mol%)using a sol-gel-based *** influence of CaO content in B_(2)O_(3)-CaO borate BG on morphology,structure and ion release behavior was investigated in *** dissolution(ion release)and crystallization could be observed in borate BGs when CaO content increased,while the morphology was not significantly altered by increasing CaO *** results evidenced that the ion release behavior of borate BGs could be tailored by tuning the B_(2)O_(3)/CaO molar *** also evaluated the in vitro cytotoxicity,hemostatic,antibacterial and angiogenic activities of borate *** was validated for all borate ***,borate BGs exhibited composition-dependent hemostatic,antibacterial and angiogenic ***,higher contents of Ca in borate BGs facilitated hemostatic activity,while higher contents of B_(2)O_(3) were beneficial for pro-angiogenic *** synthesized sol-gel-derived borate BGs are pr.mising materials for developing advanced wound healing dressings,given their fast ion release behavior and favorable hemostatic,antibacterial and angiogenic activities.

关键词： borate glasses sol-gel processing glass composition wound healing

Energy enhancement of laser-driven ions by radiation reaction and Breit-Wheeler pair production in the ultra-relativistic transparency regime

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High Power Laser Science and Engineering 2024年第1期12卷 60-73页

作者： Shikha Bhadoria mattias marklund christoph H.Keitel max-Planck-Institut für Kernphysik HeidelbergGermany Depar.ment of Physics University of GothenburgGöteborgSweden

The impact of radiation reaction and Breit±Wheeler pair production on the acceleration of fully ionized carbon ions driven by an intense linearly polarized laser pulse has been investigated in the ultra-relativistic transparency *** initial expectations, the radiation reaction and pair production at ultra-high laser intensities are found to enhance the energy gained by the ions. The electrons lose most of their transverse momentum, and the additionally produced pair plasma of Breit±Wheeler electrons and positrons co-streams in the forward direction as opposed to the existing electrons streaming at an angle above zero degree. We discuss how these observations could be explained by the changes in the phase velocity of the Buneman instability, which is known to aid ion acceleration in the breakout afterburner regime, by tapping the free energy in the relative electron and ion streams. We present evidence that these non-classical effects can further improve the highest carbon ion energies in this transparency regime.

关键词： ion acceleration quantum electrodynamic effects

Implementation and validation of a bonded particle model to predict rheological properties of viscoelastic materials

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Particuology 2024年第6期89卷 198-210页

作者： michael mascara Arno mayrhofer Stefan radl christoph Kloss Institute of Process and Particle Engineering Graz University of TechnologyInffeldgasse 13Graz8010Austria DCS Computing GmbH Industriezeile 35Linz4020Austria

This work focuses on implementing a particle-based method able to characterize viscoelastic materials whose rheological properties,such as storage modulus G′and loss modulus G″,are *** is based on the bonded particle model,with the elastic constitutive relation here substituted with a viscoelastic one to capture time-scale *** Burgers model,vastly used in literature to model viscoelastic systems,is discretized and *** test case used for calibration comprises of a cubic lattice,sheared with a periodic motion,to mimic the effect of a shear *** appropriate filtering of the stress response,the rheological properties are obtained,highlighting the effect of the lattice geometry,as well as the particle size,on the accuracy of the ***,the Burgers par.meters are calibrated by analytically fitting the exper.mental dataset,showing the limitation of the Burgers *** micro-contact par.meters are obtained fr.m the macro par.meters through appropriate *** completing a frequency sweep,the simulated G′and G″show a relatively large error,around 25%for G’for *** this reason,a more robust model,namely the generalized maxwell model,has been *** calibration procedure is performed in the same fashion as for the Burgers ***,the tangential micro-contact par.meters are scaled *** normal *** scaling par.meter,calledα,is calibrated by minimizing the root mean square error between simulation and exper.mental data,giving errors below 10%in both G′and G″for a large ***,a full ring plate-plate rheometer setup is simulated,and the simulation is compared with the given exper.mental dataset,again finding a good agreement.

关键词： DEm rheology Numerical modeling Viscoelasticity

recycled graphite for.more sustainable lithium-ion batteries

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Carbon Energy 2024年第5期6卷 15-24页

作者： mayokun Olutogun Anna Vanderbruggen christoph Frey martin rudolph Dominic Bresser Stefano Passerini Helmholtz Institute Ulm(HIU) Ulm Germany Karlsruhe Institute of Technology(KIT) KarlsruheGermany Helmholtz Zentr.m Dresden-rossendorf(HZDr) Helmholtz Institute Freiberg for Resource Technology(HIF)FreibergGermany ProGraphite GmbH UntergriesbachGermany Chemistry Depar.ment Sapienza University of RomeRomeItaly

The demand for lithium-ion batteries(LIBs)is driven largely by their use in electric vehicles,which is projected to increase dr.matically in the *** great success,however,urgently calls for the efficient recycling of LIBs at the end of their ***,we describe a froth flotation-based process to recycle graphite—the predominant active material for the negative electrode—fr.m spent LIBs and investigate its reuse in newly assembled *** has been found that the structure and morphology of the recycled graphite are essentially unchanged compared to pristine commercial anode-grade graphite,and despite some minor impurities fr.m the recycling process,the recycled graphite provides a r.markable reversible specific capacity of more than 350 mAh g^(−1).Even more importantly,newly assembled graphite‖NmC532 cells show excellent cycling stability with a capacity retention of 80%after 1000 cycles,that is,comparable to the performance of reference full cells comprising pristine commercial graphite.

关键词： anode graphite lithium-ion battery recycling sustainability

Towards engineering a portable platform for laparoscopic pre-training in virtual reality with haptic feedback

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虚拟现实与智能硬件（中英文） 2024年第2期6卷 83-99页

作者： Hans-Georg ENKLEr Wolfgang KUNErT Stefan PFEFFEr Kai-Jonas BOCK Steffen AXT Jonas JOHANNINK christoph rEICH Furtwangen University 78120 FurtwangenGermany University Hospital and Faculty of medicine Tuebingen 72076 TuebingenGermany

Background Laparoscopic surgery is a surgical technique in which special instr.ments are inserted through small incision holes inside the *** some time,efforts have been made to improve surgical pre training through practical exercises on abstracted and reduced *** The authors strive for a portable,easy to use and cost-effective Virtual reality-based(Vr)laparoscopic pre-training platform and therefore address the question of how such a system has to be designed to achieve the quality of today's gold standard using real tissue *** Vr controllers are limited regarding haptic *** haptic feedback is necessary or at least beneficial for laparoscopic surgery training,the platform to be developed consists of a newly designed prototype laparoscopic Vr controller with haptic feedback,a commercially available head-mounted display,a Vr environment for simulating a laparoscopic surgery,and a training *** To take full advantage of benefits such as repeatability and cost-effectiveness of Vr-based training,the system shall not require a tissue sample for haptic *** is currently calculated and visually displayed to the user in the Vr *** the prototype controller,a first axis was provided with perceptible feedback for test *** of the prototype Vr controllers can be combined to simulate a typical both-handed use case,e.g.,laparoscopic suturing.A Unity based Vr prototype allows the execution of simple standard *** The first prototype enables full operation of a virtual laparoscopic instr.ment in *** addition,the simulation can compute simple interaction *** challenges lie in a realistic real-time tissue simulation and calculation of forces for the haptic *** weaknesses were identified in the first hardware prototype,which will be improved in subsequent *** degrees of freedom of the controller are to be provided with haptic *** make forces t

关键词： Laparoscopic surgery Training Virtual reality Controller Haptic feedback Kinesthetic skills

Prospective cohort study on facial profile changes in infants with robin sequence and healthy controls

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World Journal of Pediatrics 2024年第6期20卷 581-589页

作者： Cornelia Wiechers Julian Sowula Karen Kreutzer christoph E.Schwarz Christina Weismann michael Kr.mmel Christian F.Poets Bernd Koos Depar.ment of Neonatology Tuebingen University HospitalCalwerstrasse 772076 TuebingenGermany Center for Cleft Lip Palate and Craniofacial MalformationsTuebingen University HospitalTuebingenGermany Depar.ment of Orthodontics Tuebingen University HospitalTuebingenGermany Depar.ment of Oral and maxillofacial Surgery Tuebingen University HospitalTuebingenGermany

Background Various conservative and surgical approaches exist to treat robin sequence(rS),but their effects on facial profile and mandibular catch-up growth are unclear.A functional treatment concept,used in our centre for 25 years,includes an individualized palatal plate with a velo-pharyngeal extension and intensive feeding *** We performed a prospective study to objectively describe facial profiles in infants with rS treated with the above *** with isolated rS were admitted to our tertiary perinatal and national referral centre for craniofacial malformations between may 2018 and Nov *** with rS received 3D-photographs during clinically indicated *** controls were recruited fr.m Dec 2018 to Sep 2019 and received 3D-photographs every 3 *** digitally measured jaw index(JI),defined as alveolar overjet(O)x maxillary arch(U)/mandibular arch(L),and the soft tissue reference points A’-point,Nasion’,B’-point angle(ANB’),describing the relative position of maxilla to mandible,were *** mixed models were used to examine time trajectories in JI and ANB’.results A total of 2073D images,obtained in 19 infants with rS and 32 controls,were *** and ANB’decreased over time in both groups[for JI−0.18(95%CI−0.25 to−0.10);for ANB’:−0.40°per.month[(95%CI−0.48 to−0.32)]]but r.mained lower in controls[for JI−2.5(95%CI−3.2 to−1.8);for ANB’-1.7°(95%CI−2.4 to−1.0)].Also,the ANB’model showed a significant effect of the interaction term diagnosis x *** Based on longitudinal 3D images,we describe changes in objective par.meters of facial profile in infants with and without rS during the first year of *** findings indicate catch-up growth in infants treated for rS.

关键词： Infant mandibular catch-up growth Pre-epiglottic Baton Plate robin sequence Three-dimensional photography

Optical probing of ultrafast laser-induced solid-to-overdense-plasma transitions

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Light(Science & Applications) 2024年第5期13卷 973-984页

作者： Yasmina Azamoum Georg Alexander Becker Sebastian Keppler Guillaume Duchateau Stefan Skupin mickael Grech Fabrice Catoire Sebastian Hell Issa Tamer.marco Hornung marco Hellwing Alexander Kessler Franck Schorcht malte christoph Kaluza GSI Helmholtzzentr.m für Schwerionenforschung Planckstr.164291 DarmstadtGermany. Helmholtz Institute Jena Fröbelstieg 307743 JenaGermany. Institute of Optics and Quantum Electronics Friedrich-SchillerUniversität JenaMax-Wien-Platz 107743 JenaGermany. CEA-CESTA 15 Avenue des SablièresCS6000133116 Le BarpCedexFrance Institut Lumière matière UMR 5306-CNRSUniversitéde Lyon 169622 VilleurbanneFrance. LULI CNRSCEASorbonne UniversitéInstitut Polytechnique de ParisPalaiseauFrance. Universitéde Bordeaux-CNrS-CEA CELIAUMR 5107 TalenceFrance

Understanding the solid target dynamics resulting fr.m the interaction with an ultrashort laser pulse is a challenging fundamental multi-physics problem involving atomic and solid-state physics,plasma physics,and laser *** of the initial interplay of the underlying processes is essential to many applications ranging fr.m lowpower laser regimes like laser-induced ablation to high-power laser regimes like laser-driven ion *** the properties of the so-called pre-plasma formed as the laser pulse’s rising edge ionizes the target is complicated fr.m the theoretical and exper.mental point of view,and many aspects of this laser-induced transition fr.m solid to overdense plasma over picosecond timescales are still open *** the one hand,laser-driven ion acceleration requires precise control of the pre-plasma because the efficiency of the acceleration process crucially depends on the target properties at the arrival of the relativistic intensity peak of the *** the other hand,efficient laser ablation requires,for example,preventing the so-called“plasma shielding”.By capturing the dynamics of the initial stage of the interaction,we report on a detailed visualization of the pre-plasma formation and ***-thin diamond-like carbon foils are shown to transition fr.m solid to plasma during the laser rising edge with intensitiesm^(2).Single-shot near-infrared probe transmission measur.ments evidence sub-picosecond dynamics of an expanding plasma with densities above 10^(23)cm^(−3)(about 100 times the critical plasma density).The complementarity of a solid-state interaction model and kinetic plasma description provides deep insight into the interplay of initial ionization,collisions,and expansion.

关键词： laser acceleration solid