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Monte Carlo simulation of an antiproton annihilation detector system

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Chinese Science Bulletin 2009年第19期54卷 3494-3500页

作者： zhang ZhongDong1,2 1 Institute of Nuclear Physics, Forschungszentrum Jülich, D-52425 Jülich, Germany 2 State Nuclear Power Technology Corporation Ltd., Beijing 100140, China Institute of Nuclear Physics Forschungszentrum Jülich D-52425 Jülich Germany State Nuclear Power Technology Corporation Ltd. Beijing 100140 China

A renewed antiproton annihilation detector system has been developed for the ATRAP (Antihydrogen Trap Collaboration) experiment at CERN (European Organization for Nuclear Research). It counts the antihydrogen atoms and determines the annihilation vertex of the atoms. This diagnostic element will allow to optimize the production of cold antihydrogen sufficiently to permit the optical observations and measurements. Extensive Monte Carlo simulations concerning the detector system have been developed. Different event generators as well as different geometry representations were established and evaluated. Real-time measurement with the detector system was performed and the results are calibrated via the Monte Carlo simulations.

关键词：反质子仿真模拟 CERN

青海都兰过去2000年来的气候重建及其变迁

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地球科学进展 2000年第2期15卷 215-221页

作者：康兴成张其花 Lisa J.Graum lich Paul Sheppard 中国科学院兰州冰川冻土研究所兰州730000 Laboratory of Tree-Ring Research University of Arizona

根据青海都兰地区树木年轮样本建立了目前我国最长的年轮年表序列。通过年表与气候要素间相关函数、响应函数及响应面分析 ,选择了可被重建的气候因子 ,建立了重建方程 ,恢复了青海都兰地区历史时期的平均温度 ;并分析讨论了近 2 0 0 0... 详细信息

根据青海都兰地区树木年轮样本建立了目前我国最长的年轮年表序列。通过年表与气候要素间相关函数、响应函数及响应面分析 ,选择了可被重建的气候因子 ,建立了重建方程 ,恢复了青海都兰地区历史时期的平均温度 ;并分析讨论了近 2 0 0 0年来该地区的气候变化。阐述了这个地区的冷暖交替及周期循环。对一些重大气候事件 ,如中世纪暖期、小冰期和近一个世纪以来的升温等 ,逐个事件进行了剖析。并与全球温度变化进行了对照。都兰温度曲线为青藏高原东部地区提供了一个较好的气候变化信息表。

关键词：树木年轮气候重建温度气候变化 2000年

Quantitative phase-field simulation of the entire solidification process in one hypereutectic Al–Si alloy considering the effect of latent heat

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Progress in Natural Science:Materials International 2021年第3期31卷 428-433页

作者： Kai Wang Lijun zhang Institute for Energy and Climate Research IEK-2 Forschungszentrum Jülich State Key Laboratory of Power Metallurgy Central South University

The multi-phase-field(MPF) model coupled with reliable CALPHAD thermodynamic/atomic mobility descriptions, appropriate faceted anisotropy and key experimental validation is employed to perform the quantitative simulation of the microstructure evolution of the hypereutectic Al-16 wt%Si alloy during solidification. By considering the effect of latent heat released during the eutectic phase transformation in the simulation, the appropriate entire solidification sequence is obtained. All the characteristics in the as-cast microstructure can be nicely reproduced, including the primary(Si) encircled by the second primary(Al) halo, and the coupled eutectic grains appearing at the Liquid/(Al) interface rather than Liquid/(Si) interface. Moreover, three types of growth patterns of eutectic(Si) with different lengths are distinguished according to the distance between primary(Si)and the nucleation position of eutectic(Si). Furthermore, the evaluated ratios of width to length for 50 eutectic(Si) grains due to the MPF simulation are in good agreement with the experimental data. The quantitative phasefield simulation of the entire solidification process of the hypereutectic Al-16 wt%Si alloy in the present work is anticipated to pave the way for revealing the grain refinement mechanism in hypereutectic Al–Si alloys in the future studies.

关键词： Al–Si hypereutectic Alloy Solidification Phase-field simulation Latent heat Eutectic (Si)

Characterization and quantification of multi-field coupling in lithium-ion batteries under mechanical constraints

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Journal of Energy Chemistry 2024年第8期95卷 364-379,I0009页

作者： Xue Cai Caiping zhang Zeping Chen Linjing zhang Dirk Uwe Sauer Weihan Li National Active Distribution Network Technology Research Center Beijing Jiaotong UniversityBeijing 100044China Chair for Electrochemical Energy Conversion and Storage Systems Institute for Power Electronics and Electrical Drives(ISEA)RWTH Aachen UniversityCampus Boulevard 8952074 AachenGermany Center for Ageing Reliability and Lifetime Prediction of Electrochemical and Power Electronic Systems(CARL)Campus-Boulevard 8952074 AachenGermany Juelich Aachen Research Alliance JARA-EnergyAachenGermany Helmholtz Institute Münster(HI MS) IEK-12Forschungszentrum JülichGermany

The safety and durability of lithium-ion batteries under mechanical constraints depend significantly on electrochemical,thermal,and mechanical fields in *** and quantifying the multi-field coupling behaviors requires interdisciplinary ***,we design experiments under mechanical constraints and introduce an in-situ analytical framework to clarify the complex interaction mechanisms and coupling degrees among multi-physics *** proposed analytical framework integrates the parameterization of equivalent models,in-situ mechanical analysis,and quantitative assessment of coupling *** results indicate that the significant impact of pressure on impedance at low temperatures results from the diffusion-controlled step,enhancing kinetics when external pressure,like 180 to 240 k Pa at 10℃,is *** diversity in control steps for the electrochemical reaction accounts for the varying impact of pressure on battery performance across different *** thermal expansion rate suggests that the swelling force varies by less than 1.60%per unit of elevated temperature during the lithiation *** introducing a composite metric,we quantify the coupling correlation and intensity between characteristic parameters and physical fields,uncovering the highest coupling degree in electrochemical-thermal *** results underscore the potential of analytical approaches in revealing the mechanisms of interaction among multi-fields,with the goal of enhancing battery performance and advancing battery management.

关键词： Lithium-ion battery Muti-field coupling Mechanical constraints Interaction mechanisms Quantitative analysis

Sign-reversible valley-dependent Berry phase effects in 2D valley-half-semiconductors

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npj Computational Materials 2021年第1期7卷 1435-1441页

作者： Xiaodong Zhou Run-Wu zhang Zeying zhang Wanxiang Feng Yuriy Mokrousov Yugui Yao Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement(MOE)School of PhysicsBeijing Institute of Technology100081 BeijingChina Beijing Key Lab of Nanophotonics&Ultrafine Optoelectronic Systems School of PhysicsBeijing Institute of Technology100081 BeijingChina College of Mathematics and Physics Beijing University of Chemical Technology100029 BeijingChina Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARA52425 JülichGermany Institute of Physics Johannes Gutenberg University Mainz55099 MainzGermany

Manipulating valley-dependent Berry phase effects provides remarkable opportunities for both fundamental research and practical ***,by referring to effective model analysis,we propose a general scheme for realizing topological magneto-valley phase *** importantly,by using valley-half-semiconducting VSi2N4 as an outstanding example,we investigate sign change of valley-dependent Berry phase effects which drive the change-in-sign valley anomalous transport characteristics via external means such as biaxial strain,electric field,and correlation *** a result,this gives rise to quantized versions of valley anomalous transport *** findings not only uncover a general framework to control valley degree of freedom,but also motivate further research in the direction of multifunctional quantum devices in valleytronics and spintronics.

关键词： Berry phase reversible

New selection rule of resonant Raman scattering in MoS_(2) monolayer under circular polarization

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Journal of Materials Science & Technology 2022年第7期102卷 132-136页

作者： Jianqi Huang Zhiyong Liu Teng Yang Zhidong zhang Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

The first-order resonant Raman spectra of monolayer MoS_(2)are calculated under the circularly polarized *** anomalously nonzero Raman intensity of the in-plane E mode under the Z(σ+σ+)Zor Z(σ−σ−)Zgeometry,which goes against the conventional selection rule,appears under some circum-stances when optical absorption occurs at some special reciprocal points between the zone-center Γ and the zone-edge-center M *** that moment,the valley selectivity to the circular polarization is *** analysis shows that the anomalous Raman intensity of the E mode for the same circularly polarized incident and scattered light is consistent with the pseudo-angular-momentum conservation *** cal-culated E Raman tensor of monolayer MoS_(2)is found to vary with laser *** two diagonal terms of the Raman tensor change their signs from mutually opposite to the same when the relative intensity of the in-plane E mode to the out-of-plane A'_(1)mode increases,indicating the increasingly important role played by the Frölich-type electron-phonon interaction over the deformation *** study may shed new light on the understanding of the novel electron-photon process and assist in the design of new type of optoelectronic devices.

关键词： First principles calculation Resonant Raman Helicity selection rule MoS2 monolayer

Strong hopping induced Dzyaloshinskii–Moriya interaction and skyrmions in elemental cobalt

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npj Computational Materials 2019年第1期5卷 708-713页

作者： Hu-Bin Luo Hong-Bin zhang JPing Liu Key Laboratory of Magnetic Materials and Devices Ningbo Institute of Materials Technology and EngineeringChinese Academy of Sciences315201 NingboChina Department of Materials and Geosciences TU Darmstadt64287 DarmstadtGermany Department of Physics University of Texas at ArlingtonArlingtonTX 76091USA

The Dzyaloshinskii–Moriya interaction(DMI)is well known to favor a chiral rotation of the magnetic moments,which accounts for the emergence of the *** DMI is a combined effect of spin–orbit coupling with broken inversion symmetry in *** of the noncentrosymmetric magnetic materials that bear skyrmions involve nonmagnetic *** work shows that strong DMIs exist in elemental cobalt with a β-Mn-type metastable *** variation of DMI among different cobalt pairs largely follows the variation of hopping magnitude in which p electrons play an important *** the DMIs between different atomic pairs partly cancels with each other,the net interaction is sufficient to result in a left-handed Bloch-type *** dynamics simulation shows that a critical magnetic field of 2.9 T stabilizes skyrmions at 0 K.

关键词： structure cobalt interaction

Toward modeling of the scrape-off layer currents induced by electrode biasing using 2D particle-in-cell simulations

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Plasma Science and Technology 2020年第10期22卷 62-75页

作者： Huaxiang zhang Dehui LI Yunfeng LIANG Institute of Plasma Physics Chinese Academy o f SciencesHefei 230031People's Republic of China University of Science and Technology of China Hefei 230026People's Republic of China Forschungszentrum Jiilich GmbH.Institut fiir Energie und Klimaforschung Plasmaphysik.Trilateral Euregio Cluster D-52425 JiilichGermany

The property of scrape-off layer(SOL) currents induced by a biased electrode is investigated by fully kinetic collisionless two-dimensional particle-in-cell(PIC) simulations. A reduced Vlasov–Darwin model is employed, which is capable of describing the low-frequency kinetic behavior without electromagnetic vacuum modes(w^2=w_(pe)~2+ c^2k^2). A linear decay distribution of electron currents parallel to the background magnetic field is exhibited. Simulation analyses indicate that the cross field ion current is a key factor in sheath formation and global current balance. The influences of electrode area, biasing voltage and plasma source on the SOL current profile are studied, *** plasma parameters in the far SOL region of the EAST tokamak are used in simulations to assess the current driving ability of the electrode biasing method. Due to the limitations of computational power, the geometrical size of the simulation domain is significantly smaller than the realistic SOL, which may lead to an absence of the quasi-neutral region in the upstream *** last, a heuristic method is proposed to calculate the upper bound of the total current strength.

关键词： scrape-off layer electrode biasing particle-in-cell

Formation mechanism and control strategy for particulate nitrate in China

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Journal of Environmental Sciences 2023年第1期123卷 476-486页

作者： Haichao Wang Keding Lu Zhaofeng Tan Xiaorui Chen Yuhan Liu Yuanhang zhang School of Atmospheric Sciences Sun Yat-sen UniversityGuangzhou 510275China State Key Joint Laboratory of Environmental Simulation and Pollution Control College of Environmental Sciences and EngineeringPeking UniversityBeijing 100871China Institute of Energy and Climate Research IEK-8:TroposphereForschungszentrum Jülich GmbHJülich 52428Germany Department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityHong Kong 999077China China Institute of Atomic Energy Beijing 100193China

Over the past decade,fine particulate matter(PM)pollution in China has been abated significantly,benefiting from strict emission control measures,but particulate nitrate continues to ***,we review the progress in particulate nitrate(p NO3-)pollution characterization,nitrate formation mechanisms,and the proposed control strategies in *** spatial and temporal distributions of p NO3-are *** current status of knowledge on the chemical mechanism is updated,and the significance of its formation pathways is assessed by various approaches such as field observation and modelling of nitrate production rate,as well as isotopic *** factors impacting p NO3-formation and the corresponding pollution regulation strategies are discussed,in which the importance of atmospheric oxidation capacity and ammonia are ***,the challenges and open questions in p NO3-pollution control in China are outlined.

关键词： Particulate nitrate Reactive nitrogen Particulate matter Formation mechanism Air pollution control