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25 March 2017, Volume 34 Issue 2 Previous Issue    Next Issue

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Progress in Research on Stochastic Neutron Dynamics and Its Numerical Simulation YANG Junyun, YING Yangjun, XIAO Gang 2017, 34(2): 127-141.  Abstract ( )   HTML ( )   PDF (2459KB) ( )   Stochastic neutron dynamics is important task in nuclear power plant design and nuclear reactor safety. In this paper, basic concepts and research methods for stochastic neutron kinetics are introduced and historical development and research status in the field are sketched out. Multiplicities of fission neutrons and photons are main sources of zero power reactor noise. Based on description equation of neutron fluctuation and its solution, stochastic theory of zero power and power reactor noise is evolved. Stochastic neutron dynamics are applied in important areas such as reactivity microscopic measurement, power reactor noise measurement and analysis, nuclear criticality excursion analysis, nuclear material detection and identification and so on. In the past half century, however, it lacks available method and tool to implement quantitative analysis of problems such as probability distribution of burst waiting time of neutron initiation in pulse reactor. In recent years, important progress is made in generalized semi-Markov process simulation method, which is applied to stochastic neutron kinetic process simulation. It reveals inherent law of neutron initiation experiments conducted in pulse reactor. At last, research topics to be solved in stochastic neutron dynamics are discussed.

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Study on Disposing High-Level Transuranic Waste Aste in a Fusion Fission Reactor SHEN Yaosong, LI Kaibo, SHI Xueming, DENG Li 2017, 34(2): 142-148.  Abstract ( )   HTML ( )   PDF (2399KB) ( )   We propose a method of burning high-level transuranic waste combining with Th-U fuel cycle in a subcritical reactors driven by external fusion neutron sources. Corresponding one-dimension model is built by means of ONESN_BURN code with new data libraries. Numerical results, including actinide radioactivity, biological hazard potential, and high burn-up rate of high-level transuranic waste are obtained. Comparison with thermal reactor shows that the harder neutron spectrum is the more efficient than the soft one.

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Calculation of Average Thermonuclear Reaction Rate Under Unthermal Balance CHANG Kai, LI Jinhong, SHEN Huayun, ZHONG Bin 2017, 34(2): 149-154.  Abstract ( )   HTML ( )   PDF (1522KB) ( )   Importance of accurate calculation of average reaction rate in thermonuclear reactions is introduced. Two types of nuclear involved in thermonuclear reactions are assumed in thermal equilibrium state under same temperature. With comparison between analytical expressions of average reaction rate and average rate of thermonuclear reaction using MC method directly, correctness of MC method is obtained. Finally, MC method is extended to calculation of average thermonuclear reaction rate in several typical distributions.

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Equation of State of Detonation Products for HMX Explosive ZHAO Yanhong, ZHANG Gongmu, ZHANG Qili, LI Qiong 2017, 34(2): 155-159.  Abstract ( )   HTML ( )   PDF (950KB) ( )   Equation of state of detonation products for HMX explosive is calculated. Detonation velocity and detonation pressure at CJ point are calculated as initial density of HMX explosive is 1.90 g·cm-3. It shows satisfactory agreement with experimental data. Mole numbers of various detonation products are predicted and compared with results of BKW and LJD. Pressure, γ and mole numbers of detonation products along CJ adiabatic expansion path are given. They are helpful for understanding phenomenon of detonation.

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Monte-Carlo Simulation on Experiment of Range for Iron Ions Implanted into Plant Seeds WANG Linxiang 2017, 34(2): 160-164.  Abstract ( )   HTML ( )   PDF (1280KB) ( )   Current study shows that range distribution of ions implantated into plant seeds obtained with TRIM program are far from experimental data. According to characters of microstructure of plant seeds, microstructure models and calculation programs are designed. With Monte-Carlo simulation range distributions are calculated for iron ions implanted into peanut, color cotton and wheat seed at different energies (110 keV, 20 keV, 200 keV) and different doses (2×1016 ions·cm-2, 5×1016 ions·cm-2, 1017 ions·cm-2, 2×1017 ions·cm-2). The results agree well with experimental results. A random sampling simulation method is obtained for interaction between implantation ions and seed microstructure, which provides an idea for theoretical study of interaction between implantation ions and organisms.

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Study of Rough Wall Heat Flux in Hypersonic Turbulent Flow LI Junhong, ZHANG Liang, YU Jijun, CHENG Xiaoli 2017, 34(2): 165-174.  Abstract ( )   HTML ( )   PDF (3962KB) ( )   Heat transfer distribution is analyzed on a rough wall in high speed turbulent compressible flow via computational fluid dynamics(CFD) method and analytical correlations, focusing on heat transfer with different roughness number and roughness element shape. It shows that, in all cases, heat flux augmentation predicted with CFD increases with reduction of roughness element density and levels off after roughness shape density is small, which differs with data of three analytical correlations. Predicted heat fluxes are same if same roughness element density and equivalent height are imposed on analytical correlations distinguishing from tendency of CFD results, which changes with roughness element shapes.

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Entropy Stable Scheme Based on Moving Meshesfor Hyperbolic Conservation Laws CHENG Xiaohan, NIE Yufeng, CAI Li, FENG Jianhu 2017, 34(2): 175-182.  Abstract ( )   HTML ( )   PDF (3159KB) ( )   An entropy stable scheme based on moving meshes is proposed for hyperbolic conservation laws. The method employs equidistribution principle to redistribute mesh points. Numerical solutions on new meshes are updated by using a conservative-interpolation formula. Entropy stable fluxes and third order strong stability-preserving Runge-Kutta time evolution method are employed to obtain numerical solutions at next time level. Several test problems are presented to demonstrate that the method not only improves resolution in discontinuous areas, but also reduces possible spurious oscillations.

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A Recovery Prediction Model for Solvent Enhanced Steam Flooding in Thin Heavy Oil Reservoirs LIU Hao, CHENG Linsong, YANG Zhijun, HUANG Shijun, LI Chunlan, ZHANG Zhongyi 2017, 34(2): 183-192.  Abstract ( )   HTML ( )   PDF (3123KB) ( )   With analyses of field production data and numerical simulations,solvent-enhanced steam flooding (SESF) production process is divided into three stages. By integrating mass conservation equation, energy conservation equation, motion equation and diffusion equation, a mathematical model was obtained to describe steam front development.The expression is a typical Volterra integral function of the second kind and could be transformed by Laplace transformation.It is solved by discretizing time and space into small intervals. With comparison of calculated results and those of STARS, relative error of less than 4% for whole process is found. The model provides an accurate and quick method for analyzing effects of solvent properties and injection strategies on SESF production process.

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An Improved Chaotic Ant Swarm Algorithm for Simultaneous Synthesis of Heat Exchanger Network ZHANG Chunwei, CUI Guomin, CHEN Shang 2017, 34(2): 193-204.  Abstract ( )   HTML ( )   PDF (2465KB) ( )   An improved chaotic ant swarm algorithm, which synthesizes simultaneously heat exchanger network well, is proposed. Organization variables update strategy and novel dynamic neighborhood topology are introduced to enhance global search ability and local search ability of the algorithm. Two strategies of integer variables are proposed to optimize integer variables represented by heat exchangers. Two heat exchanger network problems with different scale are selected to test the algorithm. Obtained solutions are better than solutions published in literature, which indicates robustness and effectiveness of the algorithm.

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Application of Scaled Boundary Finite Element Method in Electromagnetic Field Problems LIANG Yanping, DING Xin, CHEN Yuanqi, YU Honghao 2017, 34(2): 205-213.  Abstract ( )   HTML ( )   PDF (1846KB) ( )   Scaled boundary finite element method (SBFEM) is used to analysis and calculate electromagnetic field problems. SBFEM equation and discrete format of irrotational magnetic fields are derived with weighted residual method. Solving method of inside common node on public edge of adjacent sub-domain is shown. A typical example that has analytical solution of electromagnetic field is used for comparative analysis, which verifies discrete format correctness and feasibility of the method. Foundation for method applications in electromagnetic field calculation is made.

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Effects of Temperature on Electromagnetic Parameters of Composite Formed with Line-Shaped Metallic Particles XU Jian, LI Jiangnan, WU Jie, LIANG Feng, CHEN Jiangwei 2017, 34(2): 214-220.  Abstract ( )   HTML ( )   PDF (2401KB) ( )   It is shown that various closed circuits formed by line-shaped metallic particles in composite induce great permeability. Effect of temperature on magnetic response is weak. Based upon effective medium theory,electric and magnetic response of composites containing line-shaped tungsten particles are addressed. Microwave absorbing composites are designed and optimized, which may be applied in high temperature circumstances.

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Effects of Potential Models on Thermal Properties of Graphene in Molecular Dynamics Simulations ZOU Jihang, YE Zhenqiang, CAO Bingyang 2017, 34(2): 221-229.  Abstract ( )   HTML ( )   PDF (1198KB) ( )   We compare Tersoff, Rebo and Airebo models in calculating thermal properties of graphene, including phonon dispersion, density of states, group velocities and thermal conductivity. It is found that phonon dispersions derived from Rebo and Airebo models are in better agreement with experiments, and density of states derived from Airebo model is close to predictions of first-principles. As for group velocities around Γ point, Rebo and Airebo models provide higher values than Tersoff model. We also find that thermal conductivity of graphene provided by Airebo model is about 1150 W·m-1·K-1, which agrees with experimental results. Compromising various factors, compared with Rebo and Tersoff models Airebo model may be suitable for describing thermal properties of graphene.

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Alloy Effects Strengthen Adsorption of H2O on PtRun Clusters LI Yong, LI Haisheng, LI Guanya, WANG Zhaowu, LI Guoling, ZUO Zhengwei, LI Liben 2017, 34(2): 230-236.  Abstract ( )   HTML ( )   PDF (5859KB) ( )   First-principles calculations are used to study alloy effects on configurations, stability and water adsorption of PtRun-1(n=2-14) and H2O-PtRun-1 (n=2-14) systems. It shows that substitution energy of a Pt atom to a Ru atom is low which manifests that Pt is easy to form alloy with Ru clusters. Compared with pure Run cluster, alloy effects enhance adsorption energy of H2O molecule on PtRun cluster, and H2O molecule is not easy to release in molecular form from PtRun cluster. Considering van de Waals force, adsorption energy of water on PtRu7 increased and dissociation barrier decreased, making it possible to split water on PtRu7. In conclusion, PtRun is suitable to be catalyst for spliting water and producing hydrogen.

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Comparative Study on Magnetic Properties of Mn/C Codoped ZnS Nanotubes CHEN Hongxia, HU Xiaoyan, ZHUANG Guoce 2017, 34(2): 237-244.  Abstract ( )   HTML ( )   PDF (2335KB) ( )   Structural, electronic and magnetic properties of ZnS nanotubes (NTs) doped with Mn atoms are studied with first-principles calculations. Formation energies of doped NTs are smaller than that of the pristine, indicating that doing process is an exothermic reaction. Band gaps of doped NTs are narrower than that of the pristine. It indicates that Mn-doped ZnS NTs tends to adopt antiferromagnetic (AFM) configuration. To obtain room temperature ferromagnetism, we replaced a S atom by a C atom. Ferromagnetic (FM) states are lower in energy than AFM states by 0.454 eV. Such energy difference implies that room temperature ferromagnetism can be expected in the system.

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Basic Properties of Two-dimensional Disk System Under Isotropic Compression ZHANG Xinggang, HU Lin 2017, 34(2): 245-252.  Abstract ( )   HTML ( )   PDF (3017KB) ( )   Theoretical analysis and numerical simulation are conducted to investigate basic properties of two-dimensional disordered disk system under quasi-static isotropic compression. Some basic concepts such as average reduced overlap, reduced pressure are introduced. Via micromechanics analysis, we deduce functional relation between reduced pressure and statistical quantities of disk system. Based on numerical simulation, variations of physical quantities such as excess average contact number, average reduced overlap, reduced pressure with excess volume fraction are studied. An approximate formula of reduced pressure is presented. These simulation results show that mechanical responses of compression are different as disk system is far from or near critical jammed state.