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Secondary decay effects of the isospin fractionation in the projectile fragmentation at GeV/nucleon

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Nuclear Science and Techniques 2020年第12期31卷 122-128页

作者： Chen-Chen Guo jun su Long Zhu Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

The isospin fractionations in 124Sn,107Sn+120Sn at 600 MeV/nucleon,and 136Xe,124Xe+208Pb at 1000 MeV/nucleon are investigated by the isospin-dependent quantum molecular dynamics model coupled with the statistical code *** yield ratio as a function of the binding energy difference for light mirror nuclei 3H/3He,7Li/7Be,11B/11C,and 15N/15O is applied to estimate the ratio between neutrons and protons in the gas of the fragmenting *** comparing the estimated values resulting from the simulations with and without the GEMINI code,it was found that the secondary decay distorts the signal of the isospin *** minimize the secondary decay effects,the yield ratio of the light mirror nuclei 3H/3He as well as its double ratio between two systems with different isospin asymmetries of the projectiles is recommended as robust isospin observables.

关键词： Quantum molecular dynamics model(QMD) Isospin fractionation Secondary decay effect

Improvement of the Bayesian neural network to study the photoneutron yield cross sections

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Nuclear Science and Techniques 2022年第11期33卷 1-9页

作者： Yong-Yi Li Fan Zhang jun su Department of Computing Changzhi UniversityChangzhi 046011China Department of Physics Changzhi UniversityChangzhi 046011China Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen UniversityZhuhai 519082China

This work is an attempt to improve the Bayesian neural network (BNN) for studying photoneutron yield cross sections as a function of the charge number Z, mass number A, and incident energy ε. The BNN was improved in terms of three aspects:numerical parameters, input layer, and network structure. First, by minimizing the deviations between the predictions and data, the numerical parameters, including the hidden layer number, hidden node number, and activation function, were selected. It was found that the BNN with three hidden layers, 10 hidden nodes, and sigmoid activation function provided the smallest deviations. Second, based on known knowledge,such as the isospin dependence and shape effect, the optimal ground-state properties were selected as input neurons. Third, the Lorentzian function was applied to map the hidden nodes to the output cross sections, and the empirical formula of the Lorentzian parameters was applied to link some of the input nodes to the output cross sections. It was found that the last two aspects improved the predictions and avoided overfitting, especially for the axially deformed nucleus.

关键词： Bayesian neural network Photoneutron cross sections Giant dipole resonance

Optimum condition by mechanical characteristic evaluation in friction stir welding for 5083-O Al alloy

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中国有色金属学会会刊：英文版 2009年第B09期19卷 17-22页

作者： Min-su HAN Seung-jun LEE Jae-Cheul park Seok-Cheol KO Yong-Bin WOO Seong-Jong KIM Division of Marine Engineering Mokpo Maritime University Chungnam Regional Innovation Agency

The mechanical characteristies for friction stir welding (FSW) of 5083-O Al alloy were evaluated. The results show that in FSW at 800 r/min and 124 mm/min, a weld defect is observed at the start point. However, the button shape at the end point is good and the stir zone has a soft appearance. At 267 mm/min, a void occurs at the button. A slight weld defect and rough stir zone are seen both at the start and end points at 342 mm/min. Moreover, at the bottom, a tunnel-type void is observed from an early stage to the end point, and at 1 800 r/min, a weld defect can be found from an early stage to the end point. These defects are rough with imperfect joining due to excessive rotation speed and high physical force. Weld fractures relative to rotational and travel speeds are observed at the stir zone. The optimum FSW conditions are a welding speed of 124 mm/min and a rotational speed of 800 r/min.

关键词：搅拌摩擦焊接摩擦特性机械性能铝合金焊缝缺陷评估优化氧

Yield of long-lived fission product transmutation using proton-, deuteron-, and alpha particle-induced spallation

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Nuclear Science and Techniques 2021年第9期32卷 73-83页

作者： Meng-Ting Jin su-Yang Xu Guan-Ming Yang jun su Sino-French Institute for Nuclear Energy and Technology Sun Yat-sen UniversityZhuhai 519082China

The transmutation of long-lived fission products through spallation induced by light nuclides was investi-gated for the purpose of determining the feasibility of this approach for long-lived fission products,in both economic and environmental *** cross-section data were obtained from the TALYS Evaluated Nuclear Data Library(TENDL).A thick target model was used to study the consumption of the target isotopes in the transmutation *** transmutation yield was calculated using the highest beam intensity available with the China initiative accelerator-driven *** was found that the light nuclide-induced spallation reaction can significantly reduce the radio toxicity of the investigated long-lived fission *** the transmutation target made of elemental LLFP and the proton beam with an intensity of 5 mA,the consumption of 90 Sr,93 Zr,107 Pd,or 137 Cs can reach approximately 500 g per year.

关键词： Transmutation Long-lived fission products Spallation

A dynamical description of the ^(136)Xe+p spallation at 1000 MeV/nucleon

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Chinese Physics C 2019年第2期43卷 99-106页

作者： Fan Zhang jun su Department of Electronic Information and Physics Changzhi University Sino-French Institute of Nuclear Engineering and Technology Sun Yat-sen University

We propose a dynamical description of the ^(136)Xe + p spallation at 1000 MeV/nucleon with the aim of probing the mechanism which rules the production of intermediate-mass fragments(IMF). The isospin-dependent quantum molecular dynamics(IQMD) model is used to describe the dynamical process of spallation until hot fragments with excitation energy less than a certain value E_(stop) are formed. The statistical code GEMINI is applied to simulate the light-particle evaporation from hot fragments. It is found that IMF production is well described by the model when E_(stop)= 2 MeV/nucleon is used. Comparison of the calculated mean neutron-to-proton ratio and the experimental data indicates that E_(stop) should be 3 MeV/nucleon.

关键词： spallation intermediate-mass fragment quantum molecular dynamics

Molecular Dynamics Simulation of Microstructure Transitions in a Large-Scale Liquid Metal Al System During Rapid Cooling Processes

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Chinese Physics Letters 2002年第8期19卷 1144-1147页

作者： Liu Rang-su, Dong Ke-jun Department of Physics Hu"nan University Department of Chemistry Hu"nan University School of Materials Science and Engineering The University of New South Wales

We perform a molecular dynamics simulation of microstructure transitions in a large-scale system consisting of 400 000 atoms of liquid metal Al by the Clare supercomputer. A cluster-type index method is proposed to describe the structures of various short-range-order clusters in the liquid system. It is demonstrated that the icosahedron cluster (12 0 12 0) plays the most important role in the microstructure transition and that some larger clusters (containing more than 130 atoms) are formed in the system during the rapid cooling processes. It is obvious that the larger clusters are formed by means of combining some middle clusters, and that the middle clusters are formed with several smaller clusters. However, the larger clusters are not formed to be the multi-shell configuration as shown in the mass spectrum analysis of the cluster configurations of Al obtained by gaseous deposition, ionic spray methods and so on. This result can be used to explain the essential distinction between the cluster configurations of Al formed in two different ways

关键词： Molecular dynamics

Effect of Ni and Mn on the Mechanical Properties of 22Cr Microduplex Stainless Steel

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Acta Metallurgica Sinica(English Letters) 2015年第1期28卷 32-38页

作者： jun-Young park Yong-Sik Ahn Department of Materials Science and Engineering Pukyong National University

The tensile properties of 22Cr–2Ni–4Mn–0.2N micro-duplex stainless steels with different Ni and Mn contents were investigated. Duplex stainless steels were vacuum induction melted and hot rolled, then annealed at 1,000–1,100 °C, at which temperature both the austenite and ferrite phases were stable. The volume fraction of the ferrite phase was markedly affected by the alloying elements of Mn and Ni; 1 wt% of Mn was equivalent to 0.4 wt% of Ni. All of the steels tested at room temperature showed the common strain-hardening behavior, while the steels tested at lower temperatures（-30 or-50 °C）showed a distinct inflection point in their stress–strain curves, which resulted from the transformation of the austenite to straininduced martensite. The onset strain（e0） of the inflection point in the stress–strain curve depended on the Md30 value of the steel. Testing at lower temperatures resulted in smaller e0 and consequently higher strengths and fracture strains（ef）. The tensile behavior was examined from the perspective of austenite stability of the micro-duplex stainless steels with the different Ni and Mn contents.

关键词： Duplex stainless steel Microstructure Mechanical property Alloy composition

Fabrication and characterization of 3D scaffold using 3D plotting system

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Chinese Science Bulletin 2010年第1期55卷 94-98页

作者： LEE jun-Hee park su-A park KoEun KIM Jae-Hyun KIM Kyung-Shik LEE Jihye Kim WanDoo Bio-Mechatronics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM) Nano-Mechanics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM) Nano-Mechatronics Team Division of Nano-Machinery Korea Institute of Machinery and Materials (KIMM)

In this paper, we design and fabricate a 3D scaffold using rapid prototyping (RP) technology for tissue engineering. The scaffold should have a three-dimensional interconnected pore network. We fabricate a polycaprolactone (PCL) scaffold with interconnecting pores and uniform porosity for cell ingrowth using a 3D plotting system. In order to keep the three dimensional shape under mechanical loading while implanted, we design an oscillating nozzle system to increase elastic modulus and yield strength of PCL strand. We characterize the influence of pore geometry, compressive modulus of the scaffold, elastic modulus and yield strength of the strand using SEM, dynamical mechanical analysis (DMA) and Nano-UTM. Finally the cell responses on scaffolds are observed.

关键词：三维形状绘图系统表征支架制作动态机械分析弹性模量细胞反应

Thermophoresis of nanoparticles hotter/colder than the surrounding dilute gases

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Particuology 2022年第4期20卷 95-102页

作者： junjie su Jie Cui jun Wang Guodong Xia MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation Beijing Key Laboratory of Heat Transfer and Energy ConversionBeijing University of TechnologyBeijing 100124China

Aerosol particles suspended in a diluted gas with non-uniform temperature distribution are expected to experience a thermophoretic *** theoretical treatment of thermophoresis,it is usually assumed that the particle temperature is equal to the surrounding gas ***,this might not always be the *** some particular applications,the particle temperature can significantly differ from the gas *** the present paper,we theoretically investigate the effect of the particle tempera-ture on the thermophoresis of nanoparticles in the free molecule *** formulas for the thermophoretic force and thermophoretic velocity are obtained based on the gas kinetic *** exam-ples,a spherical Ag nanoparticle suspended in a dilute He gas is considered,and the Rudyak-Krasnolutski potential is employed to model the gas-particle *** is found that the influence of the particle temperature on the thermophoresis of nanoparticles can be *** increasing particle size,the error due to the equal gas-particle temperature assumption can be neglected.

关键词： Thermophoresis Particle temperature Nanoparticles Free molecule regime