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Generalized time-dependent generator coordinate method for induced fission dynamics

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Frontiers of physics 2024年第4期19卷 1-12页

作者： B.Li D.Vretenar T.Nikšić j.Zhao p.w.Zhao j.Meng State Key Laboratory of Nuclear physics and Technology School of PhysicsPeking UniversityBeijing 100871China physics Department Faculty of ScienceUniversity of Zagreb10000 ZagrebCroatia Center for Circuits and Systems Peng Cheng LaboratoryShenzhen 518055China

The generalized time-dependent generator coordinate method(TD-GCM)is extended to include pairing *** correlated GCM nuclear wave function is expressed in terms of time-dependent generator states and weight *** particle–hole channel of the effective interaction is determined by a Hamiltonian derived from an energy density functional,while pairing is treated dynamically in the standard BCS approximation with time-dependent pairing tensor and single-particle occupation *** the inclusion of pairing correlations,various time-dependent phenomena in open-shell nuclei can be described more *** model is applied to the description of saddle-to-scission dynamics of induced *** generalized TD-GCM charge yields and total kinetic energy distribution for the fission of 240pu,are compared to those obtained using the standard time-dependent density functional theory(TD-DFT)approach,and with available data.

关键词： nuclear density functional theory generator coordinate method fission dynamics

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： H.T.jeong S.w.Lee w.j.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the HCpαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth

Hydromechanical characterization of gas transport amidst uncertainty for underground nuclear explosion detection

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journal of Rock Mechanics and Geotechnical Engineering 2024年第6期16卷 2019-2032页

作者： wenfeng Li Chelsea w.Neil j william Carey Meng Meng Luke p.Frash philip H.Stauffer Earth and Environmental Sciences Los Alamos National LaboratoryLos AlamosNM87544USA Department of Mineral Engineering New Mexico TechSocorroNM87801USA

Given the challenge of definitively discriminating between chemical and nuclear explosions using seismic methods alone,surface detection of signature noble gas radioisotopes is considered a positive identification of underground nuclear explosions(UNEs).However,the migration of signature radionuclide gases between the nuclear cavity and surface is not well understood because complex processes are involved,including the generation of complex fracture networks,reactivation of natural fractures and faults,and thermo-hydro-mechanical-chemical(THMC)coupling of radionuclide gas transport in the *** this study,we provide an experimental investigation of hydro-mechanical(HM)coupling among gas flow,stress states,rock deformation,and rock damage using a unique multi-physics triaxial direct shear rock testing *** testing system also features redundant gas pressure and flow rate measurements,well suited for parameter uncertainty *** porous tuff and tight granite samples that are relevant to historic UNE tests,we measured the Biot effective stress coefficient,rock matrix gas permeability,and fracture gas permeability at a range of pore pressure and stress *** Biot effective stress coefficient varies from 0.69 to 1 for the tuff,whose porosity averages 35.3%±0.7%,while this coefficient varies from 0.51 to 0.78 for the tight granite(porosityperhaps an underestimate).Matrix gas permeability is strongly correlated to effective stress for the granite,but not for the porous *** experiments reveal the following key engineering implications on transport of radionuclide gases post a UNE event:(1)The porous tuff shows apparent fracture dilation or compression upon stress changes,which does not necessarily change the gas permeability;(2)The granite fracture permeability shows strong stress sensitivity and is positively related to shear displacement;and(3)Hydromechanical coupling among stress states,rock damage,and gas flow appears to be

关键词： Underground nuclear explosion uncertainty quantification Radionuclide transport Biot effective stress coefficient Fracture permeability Matrix permeability

Selection of digital fabrication technique in the construction industry--A multi-criteria decision-making approach

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Frontiers of Structural and Civil Engineering 2024年第7期18卷 977-997页

作者： M.p.SALAIMANIMAGUDAM j.jAYApRAKASH Department of Structural and Geotechnical Engineering School of Civil EngineeringVellore Institute of TechnologyVellore 632014India

Digital fabrication techniques,in recent decades,have provided the basis of a sustainable revolution in the construction ***,selecting the digital fabrication method in terms of manufacturability and functionality requirements is a complex *** paper presents alternatives and criteria for selection of digital fabrication techniques by adopting the multi-criteria decision-making *** alternatives considered in the study are concrete three-dimensional(3D)printing,shotcrete,smart dynamic casting,material intrusion,mesh molding,injection concrete 3D printing,and thin forming *** criteria include formwork utilization,reinforcement incorporation,geometrical complexity,material enhancement,assembly complexity,surface finish,and build *** demonstrates different multi-criteria decision-making techniques,with both subjective and objective weighting *** given ranking is based on the current condition of digital fabrication in the construction *** study reveals that in the selection of digital fabrication techniques,the criteria including reinforcement incorporation,build area,and geometrical complexity play a pivotal role,collectively accounting for nearly 70% of the overall *** the evaluated techniques,concrete 3D printing emerged as the best performer,however the shotcrete and mesh molding techniques in the second and third positions.

关键词： digital fabrication multicriteria decision-making concrete 3D printing

Compressive property and energy absorption characteristic of interconnected porous Mg-Zn-Y alloys with adjusting Y addition

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journal of Magnesium and Alloys 2024年第1期12卷 171-185页

作者： j.A.Liu S.j.Liu B.wang w.B.Sun X.j.Liu Z.w.Han College of Materials Science and Engineering Key Laboratory of Automobile Materials(Ministry of Education)Jilin UniversityChangchun 130022PR China Key Laboratory of Bionic Engineering(Ministry of Education) College of Biological and Agricultural EngineeringJilin UniversityChangchun130022PR China weihai Institute for Bionics-jilin University Weihai 264205PR China

In this study,interconnected porous Mg-2Zn-xY alloys with different phase compositions were prepared by various Y additions(x=0.4,3,and 6 wt.%)to adjust the compressive properties and energy absorption *** characterization methods were then applied to identify the microstructure of the porous Mg-Zn-Y and describe the details of the second *** tests were performed at room temperature(RT),200℃,and 300℃to study the impact of the Y addition and testing temperature on the compressive properties of the porous *** experimental results showed that a high Y content promotes a microstructure refinement and increases the volume fraction of the second *** the Y content increases,different Mg-Zn-Y ternary phases appear:I-phase(Mg_(3)Zn_(6)Y),w-phase(Mg_(3)Zn_(3)Y_(2)),and LpSO phase(Mg_(12)ZnY).when the Y content ranges between 0.4%and 6%,the compressive strength increases from 6.30Mpa to 9.23 Mpa,and the energy absorption capacity increases from 7.33 Mj/m^(3)to 10.97 Mj/m^(3)at RT,which is mainly attributed to the phase composition and volume fraction of the second ***,the average energy absorption efficiency is independent of the Y *** addition,the compressive deformation behaviors of the porous Mg-Zn-Y are altered by the testing *** compressive strength and energy absorption capacity of the porous Mg-Zn-Y decrease due to the softening effect of the high temperature on the *** deformation behaviors at different temperatures are finally observed to reflect the failure mechanisms of the struts.

关键词： porous magnesium Rare earth elements Microstructure Compressive behavior Energy absorption characteristic

proteins as nanomagnets and magnetoreceptors

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Zoological Research 2024年第4期45卷 831-832页

作者： p.j.Hore Department of Chemistry University of OxfordUK

It is an appealing notion that a protein molecule could act as a nanomagnet.A genetically encodable biomolecule with a permanent magnetic moment at room temperature could have a range of applications:a magnetogenetic actuator,a magnetic tag for purifying and immobilizing enzymes,a contrast agent for magnetic resonance imaging,and a basis for a biomimetic magnetic sensing device,to name just a few.A magnetic protein could perhaps also function as the sensor in the magnetic compass that enables small songbirds to navigate the huge distances between their breeding and wintering *** though such possibilities may be,how realistic are they?

关键词： magnetic magnets enable

Characterizing objective and self-report habitual physical activity and sedentary time in outpatients with an acquired brain injury

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Sports Medicine and Health Science 2024年第4期6卷 338-343页

作者： Liam p.pellerine Katerina Miller Ryan j.Frayne Myles w.O'Brien Division of Kinesiology School of Health and Human PerformanceFaculty of HealthDalhousie UniversityHalifaxNova ScotiaCanada Acquired Brain Injury NeuroCommons Nova Scotia Health AuthorityHalifaxNova ScotiaCanada School of physiotherapy(Faculty of Health)&Department of Medicine(Faculty of Medicine) Dalhousie UniversityHalifaxNova ScotiaCanada Geriatric Medicine Research Dalhousie University&Nova Scotia HealthHalifaxNova ScotiaCanada Centre de Formation Medicale Du Nouveau-Brunswick New Brunswick&Department of MedicineUniversite de SherbrookeSherbrookeQuebecCanada

Outpatients with an acquired brain injury(ABI)experience physical,mental,and social *** can be classified into two subgroups based on mechanism of injury:mild traumatic brain injury(mTBI;e.g.,concussion)and other ABI(e.g.,stroke,brain aneurysm,encephalitis).Our understanding of habitual activity levels within ABI populations is limited because they are often collected using self-report *** purpose of this study was to,1)describe the habitual activity levels of outpatients with ABI using objective and self-report monitoring,and 2)compare the activity levels of outpatients with mTBI *** *** outpatients with other ABI(mean±standard deviation:[58±13]years,9 females)and 12 outpatients with mTBI([48±11]years,9 females)wore a thigh-worn activpAL 24 h/day(h/day)for *** with ABI averaged(6.0±2.3)h/day of upright time,(10.6±2.2)h/day of sedentary time,(5.6±2.7)h/day in prolonged sedentary bouts>1 h,(5960±3037)steps/day,and(11±13)minutes/day(min/day)of moderate-vigorous physical activity(MVpA).There were no differences between activpAL-derived upright,sedentary,prolonged sedentary time,and physical activity between the mTBI and other ABI groups(all,p>0.31).Outpatients with ABI overestimated their MVpA levels(t138 min/week)and underestimated sedentary time(-4.3 h/day)compared to self-report(all,ppite self-reporting high activity levels,outpatients with ABI objectively exhibit highly inactive and sedentary *** habitual movement behaviours of our sample did not differ by mechanism of injury(i.e.,mTBI versus other ABI).Targeting reductions in objectively measured sedentary time are needed to progressively improve the habitual movement behaviours of outpatients with ABI.

关键词： Accelerometry Stroke Brain aneurysm Encephalitis Mild traumatic brain injury Rehabilitation

wettability,reactivity,and interface structure in Mg/Ni system

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journal of Magnesium and Alloys 2024年第2期12卷 659-672页

作者： S.Terlicka N.Sobczak Ł.Maj p.Darłak j.j.Sobczak Institute of Metallurgy and Materials Science Polish Academy of Sciences25 Reymonta Str.KrakowPoland Faculty of Foundry Engineering AGH University23 Reymonta Str.KrakowPoland

The sessile drop method was applied to the experimental investigation of the wetting and spreading behaviors of liquid Mg drops on pure Ni *** comparison,the experiments were performed in two variants:(1)using the Capillary purification(Cp)procedure,which allows the non-contact heating and squeezing of a pure oxide-free Mg drop;(2)by classical Contact Heating(CH)*** high-temperature tests were performed under isothermal conditions(Cp:760℃for 30 s;CH:715℃for 300 s)using Ar+5 wt%H_(2) *** the sessile drop tests,images of the Mg/Ni couples were recorded by CCD cameras(57 fps),which were then applied to calculate the contact angles of metal/substrate *** and transmission electron microscopy analyses,both coupled with energy-dispersive X-ray spectroscopy,were used for detailed structural characterization of the solidified *** was found that an oxide-free Mg drop obtained by the Cp procedure showed a wetting phenomenon on the Ni substrate(an average contact angleθwed by fast spreading and good wetting over the Ni substrate(θ_((Cp))~20°in 5 s)to form a final contact angle ofθ_(f(Cp))~18°.In contrast,a different wetting behavior was observed for the CH procedure,where the unavoidable primary oxide film on the Mg surface blocked the spreading of liquid Mg showing apparently non-wetting behavior after 300 s contact at the test ***,in both cases,the deep craters formed in the Ni substrates under the Mg drops and significant change in the structure of initially pure Mg drops to Mg-Ni alloys suggest a strong dissolution of Ni in liquid Mg and apparent values of the final contact angles measured for the Mg/Ni system.

关键词： Magnesium-based alloys Sessile drop tests Capillary purification procedure wettability Reactivity Contact angle

On the analytical solution of transient friction in channel flows

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Applied Mathematics and Mechanics(English Edition) 2024年第8期45卷 1447-1466页

作者： F.j.GARCíA-GARCíA p.FARINAS-ALVARINO Department of Naval&Industrial Engineering Polytechnic School of EngineeringUniversity of A CorunaCampus Industrial de FerrolFerrol 15403A CorunaSpain Integraciones Técnicas de Seguridad S.A.Pol.Ind.Espiritu SantoC/Nobel15Cambre 15650A CorunaSpain

The transient friction in channel mean flows is the sum of two contributions,i.e.,the underlying laminar flow(ULF)and the purely turbulent component(pTC),and the contributions are analyzed separately by theoretical *** is found that,the transient friction may be higher or remarkably lower than that in equal-Reynolds number steady-state *** universal time constant for plane-parallel laminar flows is reported,and the role of the time constant in a turbulent mean flow is *** is shown that the time constant is related to the turbulence's frozen ***,a study of the logarithmic layer during the transient flow is accomplished,which shows that the logarithmic layer is destroyed.

关键词： transient friction transient flow unsteady channel flow