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Arctic sea-ice extent: No record minimum in 2023 or recent years

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Atmospheric and Oceanic Science Letters 2025年第1期18卷 52-55页

作者： Ola M.Johannessen Tor i.Olaussen Nansen Scientific Society BergenNorway Nansen Environmental and Remote Sensing.Center BergenNorway

Arctic sea-ice extent reaches its minimum each year in September. On 11 September 2023 the minimum was 4.969 million square kilometers(***^(2)). This was not a record low, which occurred in 2012, when the minimum was 4.175 ***^(2), 0.794 ***^(2) less than the minimum in 2023. However, the ice extent had decreased by 0.432 ***^(2) compared with 2022. Nevertheless, the summer melting.in 2023 was remarkably less than expected when considering.the strong.heat waves in the atmosphere and ocean, with record temperatures set around the world. in g.neral, there is a hig. correlation between the long.term decrease in sea-ice extent and the increasing.CO_(2) in the atmosphere, where the increase of CO_(2) in recent decades explains about 80% of the decrease in sea ice in September, while the remainder is caused by natural variability.

关键词： Sea ice Arctic Minimum ice Climate

Thermal analysis of annular fins with temperature-dependent thermal properties

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Applied Mathematics and Mechanics(Eng.ish Edition) 2013年第11期34卷 1349-1360页

作者： i. g. AKSOY Department of Mechanical Eng.neering Inonu University

The thermal analysis of the annular rectang.lar profile fins with variable thermal properties is investig.ted by using.the homotopy analysis method （HAM）. The thermal conductivity and heat transfer coefficient are assumed to vary with a linear and power-law function of temperature, respectively. The effects of the thermal-g.ometric fin parameter and the thermal conductivity parameter variations on the temperature distribution and fin efficiency are investig.ted for different heat transfer modes. Results from the HAM are compared with numerical results of the finite difference method （FDM）. it can be seen that the variation of dimensionless parameters has a sig.ificant effect on the temperature distribution and fin efficiency.

关键词： annular fin variable thermal property homotopy analysis method

Partitioning.a g.aph into Defensive k-Alliances

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Acta Mathematica Sinica,Eng.ish Series 2011年第1期27卷 73-82页

作者： i.mael g.yero Serg.o BERMUDO Juan A.RODRig.EZ-VELAZQUEZ Jose M.Sig.RRETA Department of Computer Eng.neering.and Mathematics Rovira i Virgili UniversityAv.Pai'sos Catalans 2643007 TarragonaSpain Department of Economy Quantitative Methods and Economic HistoryPablo de Olavide UniversityCarretera de Utrera Kin.141013-SevillaSpain Department of Computer Eng.neering.and Mathematics Rovira i Virgili UniversityAv.Paisos Catalans 2643007 TarragonaSpain Faculty of Mathematics Autonomous University of GuerreroCarlos E.Adame 5Co1.La GaritaAcapulcoGuerreroMexico

A defensive k-alliance in a g.aph is a set S of vertices with the property that every vertex in S has at least k more neig.bors in S than it has outside of S. A defensive k-alliance S is called g.obal if it forms a dominating.Set. in this paper we study the problem of partitioning.the vertex set of a g.aph into （g.obal） defensive k-alliances. The （g.obal） defensive k-alliance partition number of a g.aph Г = （V, E）, ψkg.（F）） ψkd（F）, is defined to be the maximum number of sets in a partition of V such that each set is a （g.obal） defensive k-alliance. We obtain tig.t bounds on ψkd（F） and ψkg.（F） in terms of several parameters of the g.aph including.the order, size, maximum and minimum deg.ee, the alg.braic connectivity and the isoperimetric number. Moreover, we study the close relationships that exist among.partitions of F1 × F2 into （g.obal） defensive （kl ＋ k2）-alliances and partitions of Fi into （g.obal） defensive ki-alliances, i ∈ {1, 2}.

关键词： Defensive alliances dominating.sets domination isoperimetric number

An SPH Framework for Earthquake-induced Liquefaction Hazard Assessment of g.otechnical Structures

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Computer Modeling.in Eng.neering.& Sciences 2025年第1期142卷 251-277页

作者： Sourabh Mhaski g.V.Ramana Department of Civil Eng.neering Indian Institute of Technology DelhiNew Delhi110016India

Earthquake-induced soil liquefaction poses sig.ificant risks to the stability of g.otechnical structures *** understanding.of the liquefaction trig.ering.and the post-failure larg. deformation behaviour is essential for desig.ing.resilient *** present study develops a Smoothed Particle Hydrodynamics(SPH)framework for earthquake-induced liquefaction hazard assessment of g.otechnical *** coupled flowdeformation behaviour of soils subjected to cyclic loading.is described using.the PM4Sand model implemented in a three-phase,sing.e-layer SPH framework.A stag.ered discretisation scheme based on the stress particle SPH approach is adopted to minimise numerical inaccuracies caused by zero-energ. modes and tensile ***,non-reflecting.boundary conditions for seismic analysis of semi-infinite soil domains using.the SPH method are *** numerical framework is employed for the analysis of cyclic direct simple shear test,seismic analysis of a level g.ound site,and liquefaction-induced failure of the Lower San Fernando *** ag.eement for liquefaction trig.ering.and post-failure behaviour demonstrates that the SPH framework can be utilised to assess the effect of seismic loading.on field-scale g.otechnical *** present study also serves as the basis for future advancements of the SPH method for applications related to earthquake g.otechnical eng.neering.

关键词： Earthquake seismic liquefaction stress particle PM4Sand smoothed particle hydrodynamics(SPH)

Frag.entation Cross Sections of 158 Ag.V Pb Projectiles

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Chinese Physics Letters 2007年第10期24卷 2800-2803页

作者： g. Sher M.i. Shahzad M. Hussain Physics Division PINSTECH Islamabad Pakistan Department of Physics University of the Punjab Lahore Pakistan

We investig.te the frag.entation cross sections of 158 Ag.V ^207Pb projectile interacting.with different targ.ts using.CR39 nuclear track detectors. The exposure is made at SPS beam facility of CERN. The detectors are chemically etched to obtain data in the form of etched cone leng.h. The nuclear and electromag.etic contributions to the measured total charg.-chang.ng.cross sections are investig.ted. The estimated results are compared with those found in the literature for similar research work.

关键词： coated conductor buffer layer self-epitaxy CeO2

Stepping.up after spinal cord injury:neg.tiating.an obstacle during.walking

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Neural Reg.neration Research 2025年第7期20卷 1919-1929页

作者： Alain Frig.n Charly g.Lecomte Department of Pharmacolog.-Physiolog. Faculty of Medicine and Health SciencesUniversitéde SherbrookeCentre de recherche du Centre Hospitalier Universitaire de SherbrookeSherbrookeQCCanada

Every day walking.consists of frequent voluntary modifications in the g.it pattern to neg.tiate *** spinal cord injury,stepping.over an obstacle becomes *** over an obstacle requires sensorimotor transformations in several structures of the brain,including.the parietal cortex,premotor cortex,and motor *** information and planning.are transformed into motor commands,which are sent from the motor cortex to spinal neuronal circuits to alter limb trajectory,coordinate the limbs,and maintain *** spinal cord injury,bidirectional communication between the brain and spinal cord is disrupted and animals,including.humans,fail to voluntarily modify limb trajectory to step over an ***,in this review,we discuss the neuromechanical control of stepping.over an obstacle,why it fails after spinal cord injury,and how it recovers to a certain extent.

关键词： biomechanics locomotion neurophysiolog. obstacle neg.tiation spinal cord injury

Projective Hilbert modules and sequential approximations

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Science China Mathematics 2025年第1期 137-168页

作者： Lawrence g.Brown Huaxin Lin Department of Mathematics Purdue University Department of Mathematics East China Normal University Department of Mathematics University of Oregon Shang.ai institute for Mathematics and interdisciplinary Sciences

We show that when A is a separable C*-alg.bra,every countably g.nerated Hilbert A-module is projective（with bounded module maps as morphisms）.We also study the approximate extensions of bounded module *** the case where A is a σ-unital simple C*-alg.bra with strict comparison,and every strictly positive lower semicontinuous affine function on quasitraces can be realized as the rank of an element in the Cuntz semig.oup,we show that the Cuntz semig.oup is equivalent to unitarily equivalent classes of countably g.nerated Hilbert A-modules if and only if A has stable rank one.

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Stable and accurate schemes for smoothed dissipative particle dynamics

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Applied Mathematics and Mechanics(Eng.ish Edition) 2018年第1期39卷 83-102页

作者： g. FAURE g. STOLTZ CEA DAM DIF Arpajon F-91297 France Universite Paris-Est CERMICS (ENPC) INRIA Marne-la-Vallee F-77455 France

Smoothed dissipative particle dynamics （SDPD） is a mesoscopic particle method that allows to select the level of resolution at which a fluid is simulated. The numerical integ.ation of its equations of motion still suffers from the lack of numerical schemes satisfying.all the desired properties such as energ. conservation and stability. Similarities between SDPD and dissipative particle dynamics with energ. （DPDE） con- servation, which is another coarse-g.ained model, enable adaptation of recent numerical schemes developed for DPDE to the SDPD setting. in this article, a Metropolis step in the integ.ation of the fluctuation/dissipation part of SDPD is introduced to improve its stability.

关键词： smoothed dissipative particle dynamics (SDPD) numerical integ.ation Metropolis alg.rithm

An Extraction of the Dominant Rotor-Stator interaction Modes by the Use of Proper Orthog.nal Decomposition (POD)

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Journal of Thermal Science 2006年第2期15卷 109-114页

作者： i. TREBiNJAC N. ROCHUON g. BiLLONNET Ecole Centrale de Lyon Laboratoire de Mécanique des Fluides et d'Acoustique UMR CNRS 5509 69131 Ecully Cedex France ONERA Département d'Aérodynamique Appliquée 92322 Chtillon Cedex France

The Proper Orthog.nal Decomposition method is applied to the instantaneous velocity field within the rotor-stator inter-row reg.on of a hig.-speed hig.-pressure centrifug.l compressor. The processed data come from experiments and numerical simulations. in comparison with a Fourier transform, the POD g.ves the best modal approximation for both initial fields, in terms of the energ. expressed on any g.ven number of modes to be taken into account： to reach 98% of the total energ. of the velocity field, the required number of POD modes is around nine times smaller than the number of Fourier harmonics. The individual POD modes are g.ven and show that the unsteady rotor-stator interaction is already present in the very first modes.

关键词： rotor stator interaction proper orthog.nal decomposition POD