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Dependence of impact regime boundaries on the initial temperatures of projectiles and targets

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Defence Technology（防务技术） 2024年第1期31卷 49-57页

作者： Stefano Signetti Andreas Heine fraunhofer-institut für Kurzzeitdynamik Ernst-Mach-InstitutEMIErnst-Zermelo-Str.479104 Freiburg im BreisgauGermany

Towards higher impact velocities,ballistic events are increasingly determined by the material *** effects might range from moderate thermal softening to full phase *** particular,it is of great interest to quantify the conditions for incipient or full melting of metals during impact interactions,which result in a transition from still strength-affected to hydrodynamic material *** this work,we investigate to which extent the respective melting thresholds are also dependent on the initial,and generally elevated,temperatures of projectiles and targets before *** is studied through the application of a model developed recently by the authors to characterize the transition regime between high-velocity and hypervelocity impact,for which the melting thresholds of materials were used as the defining *** obtained results are expected to be of general interest for ballistic application cases where projectiles or targets are *** conditions might result,for example,from aerodynamic forces acting onto a projectile during atmospheric flight,explosive shapedcharge-jet formation or armor exposure to environmental *** performed analyses also broaden the scientific understanding of the relevance of temperature in penetration events,generally known since the 1960s,but often not considered thoroughly in impact studies.

关键词： Ballistic impact Thermal effects Metallic targets Energy partitioning Homologous temperature

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)

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)

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

Laser material processing optimization using bayesian optimization: a generic tool

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Light(Advanced Manufacturing) 2024年第3期5卷 75-85页

作者： Tobias Menold Volkher Onuseit Matthias Buser Michael Haas Nico Bär Andreas Michalowski institut fuer strahlwerkzeuge(IfSW) University of Stuttgart70569 StuttgartGermany Graduate School of Excellence advanced Manufacturing Engineering(GSaME) University of Stuttgart70569 StuttgartGermany

Optimizing laser processes is historically challenging,requiring extensive and costly *** solve this issue,we apply Bayesian optimization for process parameter optimization to laser cutting,welding,and *** demonstrate how readily available Bayesian optimization frameworks enable efficient optimization of laser processes with only modest expert *** studies on laser cutting,welding,and polishing highlight its adaptability to real-world manufacturing ***,the examples emphasize that with suitable cost functions and boundaries an acceptable optimization result can be achieved after a reasonable number of experiments.

关键词： Bayesian optimization Design of experiments Laser cutting Laser welding Laser polishing

Boosting propane dehydrogenation by gallium hydride species formed in situ

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Science China Chemistry 2024年第6期67卷 1753-1755页

作者： Evgenii V.Kondratenko Leibniz-institut für Katalyse e.V. Albert-Einstein-Str.29aRostock18059Germany

An inspiring paper recently published in Nature Chemistry[1]by the group of *** Gong at Tianjin University is the motivation for this highlight *** reported results show that the understanding of reaction-induced restructuring of heterogeneous catalysts is of great importance for their targeted development because usually unstable compounds can be formed and stabilized under reaction conditions.

关键词： conditions hydride stabilized

Activating ru in the pyramidal sites of ru_(2)P-type structures with earth-abundant transition metals for achieving extremely high HEr activity while minimizing noble metal content

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Carbon Energy 2024年第9期6卷 80-92页

作者： Sayed M.El-refaei Patrícia A.russo Thorsten Schultz Zhe-Ning Chen Patrick Amsalem Norbert Koch Nicola Pinna Department of Chemistry and the Center for the Science of Materials Berlin Humboldt-Universität zu BerlinBerlinGermany Max-Planck-institut für Chemische Energiekonversion Mülheim an der RuhrGermany institut für Physik and Center for the Science of Materials Berlin Humboldt-Universität zu BerlinBerlinGermany Helmholtz-Zentrum Berlin für Materialien und Energie GmbH BerlinGermany State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouChina

rational design of efficient pH-universal hydrogen evolution reaction catalysts to enable large-scale hydrogen production via electrochemical water splitting is of great significance,yet a challenging ***,ru atoms in the ru_(2)P structure were replaced with M=Co,Ni,or Mo to produce M_(2-x)ru_(x)P *** metals show strong site preference,with Co and Ni occupying the tetrahedral sites and ru the square pyramidal sites of the CoruP and NiruP ru_(2)P-type *** presence of Co or Ni in the tetrahedral sites leads to charge redistribution for ru and,according to density functional theory calculations,a significant increase in the ru d-band *** a result,the intrinsic activity of CoruP and NiruP increases considerably compared to ru_(2)P in both acidic and alkaline *** effect is not observed for MoruP,in which Mo prefers to occupy the pyramidal *** particular,CoruP shows state-of-the-art activity,outperforming ru_(2)P with Pt-like activity in 0.5 M H_(2)SO_(4)(η10=12.3 mV;η100=52 mV;turnover frequency(TOf)=4.7 s^(-1)).It remains extraordinarily active in alkaline conditions(η10=12.9 mV;η100=43.5 mV)with a TOf of 4.5 s^(-1),which is 4x higher than that of ru_(2)P and 10x that of Pt/*** increase in the Co content does not lead to drastic loss of activity,especially in alkaline medium,where,for example,the TOf of Co_(1.9)ru_(0.1)P remains comparable to that of ru_(2)P and higher than that of Pt/C,highlighting the viability of the adopted approach to prepare cost-efficient catalysts.

关键词： electrocatalysis ruthenium phosphide transition metal phosphonates

Many faces of neuronal activity manipulation in Drosophila

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Neural regeneration research 2025年第9期20卷 2574-2576页

作者： Amber Krebs Steffen Kautzmann Christian Klämbt institut für Neuro-und Verhaltensbiologie MünsterGermany

Animals exhibit complex responses to external and internal *** information is computed by interconnected neurons that express numerous ion channels,which modulate the neuronal membrane *** can neuronal activity orchestrate complex motor patterns or allow learning from previous experience?To answer such questions,we need the ability not only to record,but also to modulate neuronal activity in both space(e.g.,neuronal subsets)and time.

关键词： manipulation potential. neuronal

Discovery potential of the Glashow resonance in an air shower neutrino telescope

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Chinese Physics C 2024年第8期48卷 266-275页

作者： Guo-Yuan Huang School of Mathematics and Physics China University of GeosciencesWuhan 430074China Max-Planck-institut für Kernphysik Saupfercheckweg 169117 HeidelbergGermany

The in-ice or in-water Cherenkov neutrino telescope,such as IceCube,has already proved its power in measuring the Glashow resonance by searching for the bump around E_(ν)=6.3PeV arising from the W-boson *** are many proposals for the next few decades for observations of cosmic tau neutrinos with extensive air showers,also known as tau neutrino *** air shower telescope is,in principle,sensitive to the Glashow resonance via the channel W→τν_(τ)followed by the tau decay in the air(e.g.,TAMBO,which has a geometric area of approximately 500km^(2)).Using a thorough numerical analysis,we find that the discovery significance can be up to 90%with a TAMBO-like setup if PeV neutrinos primarily originate from neutron decays,considering the flux parameters measured by IceCube as the *** presence of new physics affecting the neutrino flavor composition can also increase the ***,if ultrahigh-energy neutrinos are dominantly produced from meson decays,it will be statistically difficult for an advanced proposal such as TAMBO to discriminate the Glashow resonance induced byν¯e from the intrinsicντ/ν¯_(τ)*** have identified several limitations for such advanced telescopes,in comparison with the in-ice or in-water telescope,when measuring resonances:(i)a suppressed branching ratio of 11%for the decay W→τν_(τ);(ii)the smearing effect and reduced acceptance because the daughter neutrino takes away(y)∼75%of the energy from the W decay;and(iii)a large attenuation effect for Earth-skimming neutrinos with the resonance.

关键词： Ultrahigh-energy neutrinos Neutrino telescopes Glashow resonance