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25 January 2022, Volume 39 Issue 1 Previous Issue    Next Issue
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Words from the Editor Song JIANG 2022, 39(1): 1-1.  Abstract ( )   HTML ( )   PDF (495KB) ( )

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Interview archives: Stories of a 38-year-ago paper in the Chinese Journal of Computational Physics Jie LIU, Shuo HUANG, Leilei CUI 2022, 39(1): 2-5.  Abstract ( )   HTML ( )   PDF (3059KB) ( )

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Effect of Irradiation on Mechanical Properties of Polycrystalline Copper: Crystal Plasticity Finite Element Method Hongming LI, Maosheng LI 2022, 39(1): 6-16.  DOI: 10.19596/j.cnki.1001-246x.8342 Abstract ( )   HTML ( )   PDF (12983KB) ( )   Based on irradiation hardening theory and crystal plasticity theory, tensile process of irradiated polycrystalline copper was simulated with ABAQUS finite element analysis software. Effects of irradiation on mechanical properties of materials such as yield strength, hardening process, crystal deformation are analyzed. Temporal evolution and spatial distribution of dislocation density are studied. It shows that: The yield stress of polycrystalline copper is increased with irradiation and hardening and softening phenomena in different stages are affected. The increase of irradiation dose slows the proliferation of dislocation density, and increases its spatial inhomogeneity. Plastic deformation and crystal rotation are also affected by irradiation. Under same strain condition, the greater the irradiation dose is, the greater the deformation degree is and the greater the inhomogeneity of plastic deformation distribution is. Meanwhile, with the increase of irradiation dose, the degree of crystal rotation and angular dispersion increases.

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Applications of Local Maximum-principle-preserving Linear Vertex Scheme of Second Order Convergence for Two-dimensional Diffusion Equations Shuxian ZHANG, Xudeng HANG 2022, 39(1): 17-32.  DOI: 10.19596/j.cnki.1001-246x.8337 Abstract ( )   HTML ( )   PDF (24377KB) ( )   We construct a kind of optimized control volume for general quadrilateral meshes. Based on the control volume, we devise a local linear vertex scheme (Vertex-scheme on Optimized Control volume, VOC), which is maximum-principle-preserving, and 2nd order convergent. We prove that VOC scheme is maximum-principle-preserving, linearity-preserving and 2nd order convergent if no exceptional vertex exists. On uniform rectangle meshes, we prove that the modified inverse distance weight (MIDW) scheme is approximately VOC scheme, and they are all 2nd order convergent. VOC scheme can be used to construct linear cell-centered diffusion schemes and positivity-preserving diffusion schemes. Numerical experiments verify that the scheme is 2nd order convergent on distorted meshes for diffusion equations with discontinuous coefficients. The linear scheme which adopts VOC scheme is linearity-preserving and 2nd order convergent, and the positivity-preserving scheme is also 2nd order convergent.

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Screw Dislocation Interacting with Lip-shaped Crack in Magnetoelectroelastic Media Huaimin GUO, Guozhong ZHAO, Lijuan JIANG 2022, 39(1): 33-40.  DOI: 10.19596/j.cnki.1001-246x.8344 Abstract ( )   HTML ( )   PDF (4153KB) ( )   Interreaction between a penetrating lip-shaped crack and a screw dislocation in magnetoelectroelastic media is investigated with Muskhelishvili techniques and perturbation technique. Analytic solutions for stress, magnetic induction and electric displacement caused by dislocation and lip-shaped crack in magnetoelectroelastic solid are derived. By using the generalized Peach-Koehler formula, image forces acting on a dislocation are calculated. Regularities of field intensity factors, generalized stress field and image force at different dislocation positions are obtained with numerical examples.

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Analysis of Deformation and Breakage During Bubble Collision Tengfei ZHAO, Hua ZHANG 2022, 39(1): 41-52.  DOI: 10.19596/j.cnki.1001-246x.8363 Abstract ( )   HTML ( )   PDF (11999KB) ( )   Gas-liquid two-phase flow is used to simulate double bubble collision process numerically with LES method, fluid volume method, crushing criterion and the third-generation vortex identification method. The single variable method is used to study the influence of bubble diameter ratio, relative eccentricity and relative distance between bubbles on the degree of bubble fragmentation. In the process of double bubble collision, the closer the diameter of the two bubbles is, the weaker the bubble breaking degree is. The relative eccentric distance has little effect on the bubble breaking degree. It shows that as the relative distance is less than 1, the bubble breaking degree is more obvious with the increase of the relative distance. As the relative distance is more than 1, the bubble breaking degree tends to be flat. It also shows that the third-generation vortex identification method captures the vortex position in the two-phase turbulent flow field well, and reflects sensitively the turbulent changes.

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Prediction of Water Temperature of Mixed-flow Closed Cooling Tower Based on BP Neural Network and Grey Correlation Analysis Hong LI, Lixin ZHANG, Yan REN, Ming GAO, Jingnan LIU 2022, 39(1): 53-59.  DOI: 10.19596/j.cnki.1001-246x.8376 Abstract ( )   HTML ( )   PDF (6024KB) ( )   In this study, a mixed flow closed cooling tower was tested with a control variable method. The factors affecting outlet water temperature were screened with a grey correlation analysis method. Five most important factors were taken as input features in a gray_BP neural network which was developed to predict outlet water temperature of the mixed flow closed cooling tower. These factors include inlet water temperature, wet bulb temperature, water refill temperature, circulating water flow rate and air volume, and the prediction output is outlet water temperature. The network adopts a three-layer structure, four-hidden layer neurons, and 30 000 iterations. Experimental data that involve no training set were used to validate the developed model. It shows that the gray neural network model outperforms the traditional BP neural network model. The correlation coefficient, average relative error, root mean square error are 0.998 9, 0.293 4% and 0.152 9, respectively. We concluded that the gray_BP neural network is a promising algorithm for predicting water temperature of a mixed flow closed cooling tower.

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A Heat Exchanger Network Optimization Method with Dominant Individual Multi-directional Compulsive Search Strategy Weiwei LIU, Guomin CUI, Yuan XIAO, Yue XU, Qianqian ZHAO, Guanhua ZHANG 2022, 39(1): 60-70.  DOI: 10.19596/j.cnki.1001-246x.8354 Abstract ( )   HTML ( )   PDF (3347KB) ( )   An evolutionary algorithm of multi-directional compulsive search strategy for dominant individuals is proposed to evaluate the health of global search of current population by examining individual difference index.When the optimization results stagnate for a long time, the health index becomes worse and the multi-direction forced search strategy of the dominant individual is started to expand the search direction of the dominant individual near the local optimal solution region, so as to ensure the global search ability of the algorithm.The strategy was applied to 15SP and 20SP calculation examples and results were compared with optimal results in the literature.They are decreased by 1.09% and 0.83%, respectively.It in dicates that the dominant individual multi-directional compulsive search strategy exerts fully the evolutionary potential of the dominant individual and improves the optimization efficiency of the algorithm.

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Dynamic Region Taboo Matching Strategy for Improving Competitiveness of New Heat Exchange Units Xinyu HAN, Guomin CUI, Yuan XIAO, Guanhua ZHANG, Yuan GAO 2022, 39(1): 71-82.  DOI: 10.19596/j.cnki.1001-246x.8370 Abstract ( )   HTML ( )   PDF (1368KB) ( )   In the process of optimizing heat exchange network of unstructured model with shunt nodes, heat exchange units could break the initial uniform distribution state and concentrate to the upstream region of the stream, which makes it impossible to generate new heat exchange units in the entrance region of cold and hot streams, resulting in the decrease of structural variation ability.The cause of this phenomenon and its influence on evolution are explored.And a dynamic regional taboo matching strategy is proposed.Free matching is allowed as the upstream region is empty.As the upstream node is not empty, the upstream region is cleared, which means that the generated nodes are equivalently transferred to the downstream region, so as to guarantee the matching vitality of the heat exchange unit in the upstream region, enhance competitiveness of newly generated heat exchange units in the process of structural evolution, and promote structural evolution of the heat exchange network.In the application of 15sp and 20sp examples, it is found that the strategy improves the network structure variation ability and achieves better results than existing literatures.

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A Lane Changing Model Based on High Order Conservation Model and Support Vector Machine Lican ZHANG, Mingmin GUO, Zhiyang LIN, Peng ZHANG, Yali DUAN 2022, 39(1): 83-95.  DOI: 10.19596/j.cnki.1001-246x.8339 Abstract ( )   HTML ( )   PDF (4453KB) ( )   A lane changing model for multi-lane traffic flow is proposed.It makes use of advantages of Support Vector Machine (SVM) in a binary classification problem with multi-dimensional features and combines with Conserved Higher-Order traffic flow model (CHO) in Lagrange coordinates.The original data is generated with a fully discrete car following model and preprocessed by Synthetic Minority Oversampling Technique (SMOTE) algorithm.The SVM is trained with two indexes evaluation.It shows that the lane changing model based on SVM and CHO simulates effectively real multi-lane driving behavior based on current driving environment on expressway.

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A Chip-based Electrostatic Beam Splitter Qiuyang ZHONG, Nannan ZHANG, Fansheng KONG, Wenhui LI, Jing LIN, Shengqiang LI 2022, 39(1): 96-100.  DOI: 10.19596/j.cnki.1001-246x.8345 Abstract ( )   HTML ( )   PDF (3305KB) ( )   A chip-based electrostatic beam splitter composed of six gold electrodes is proposed.Total length of the splitter is about 10 mm.Dynamic process of the loading and splitting polar molecules is simulated with classical Monte Carlo method.With the beam splitter, we can get a fix splitting ratio (0.5:0.5).If cutting off two pole electrodes, we can manipulate the splitting ratio conveniently with the voltage applied to the severed electrodes.

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Effect of Nb, Sn, Cu, Fe and Cr on Zr (0001) Surface Nodular Corrosion Resistance: First Principles Study Hui GAO, Zaifa YANG, Jingfen ZHAO, Huimin YUAN, Zhie LIU, Xian ZHAO 2022, 39(1): 101-108.  DOI: 10.19596/j.cnki.1001-246x.8328 Abstract ( )   HTML ( )   PDF (2765KB) ( )   Density functional theory is used to study the influence of Nb, Sn, Cu, Fe and Cr on the adsorption energy of oxygen on crystal face of Zr (0001).It was found that Nb, Sn and Cu promote adsorption of oxygen on the surface, and the influence of Fe and Cr on oxygen adsorption is different due to the location of the oxygen adsorption.Secondly, we studied destruction of microtexture on the oxidized surface by the alloying elements.It was found that the damage of Nb to the crystal face of Zr (0001) is the least and it can be recovered quickly, while Sn makes two chemical bonds longer, so the damage to the crystal face is great.Finally, the segregation of Sn, Fe and Cr to surface is exothermic, while the segregation of Nb and Cu to surface is endothermic.We conclude that Nb promotes the adsorption of oxygen on Zr (0001) crystal face, and the surface recovers quickly after oxidation, which preventing the entry of oxygen atoms and inhibiting the occurrence of nodular corrosion.Sn segregateds on Zr (0001) crystal face easily, which promotes the adsorption of oxygen on Zr (0001) crystal face, and causes the microstructure distortion of Zr (0001) crystal face.After oxidation, the crystal surface of Zr (0001) is damaged greatly, which promotes the rapid entry of oxygen and the occurrence of nodular corrosion.

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Dynamical Analysis and Circuit Implementation of a Memristor Synapse-coupled Ring Hopfield Neural Network Jia LUO, Liang SUN, Yinhu QIAO 2022, 39(1): 109-117.  DOI: 10.19596/j.cnki.1001-246x.8338 Abstract ( )   HTML ( )   PDF (13807KB) ( )   A new memristor model is proposed and three memristive characteristics are analyzed with standard nonlinear theory.Analog circuit of the memristor is designed.Then, a memristor synapse-coupled ring Hopfield neural network is constructed based on the memristor synapse.Special dynamical behaviors closely related to the memristor synapse are revealed by adopting bifurcation diagrams, Lyapunov exponents, time series, etc.It shows that the memristive neural network generates multiple symmetrical bursting firing patterns and complex chaotic behavior at different memristive synaptic weight.Finally, an equivalent analog circuit of the memristive neural network is designed, and correctness of MATLAB numerical simulation is verified with PSIM circuit simulations.

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Dynamics of Spiral Waves in Complex Ginzburg-Landau Systems Subjected to Feedback Derived from an Annular Domain Shaoying CHEN, Xueli WANG, Zhimei GAO, Guoyong YUAN 2022, 39(1): 118-126.  DOI: 10.19596/j.cnki.1001-246x.8360 Abstract ( )   HTML ( )   PDF (10206KB) ( )   We studied dynamics of spiral waves subjected to a feedback control, where the feedback signal is obtained with integral in an annular region.As the annular region is circular, the spiral tip usually enters a circular attractor after a transient drift, and radius of the attractor varies periodically with parameters of the annular region.With the change of these parameters, drift direction of the spiral tip at the beginning of feedback also has a periodic change.In the phase of transient drift, modulus function of the complex feedback signal is bell-shaped, and the steepness of the bell is related to the smoothness of the drift trajectory.The sign and value of the feedback gain affect the dynamical behavior of the controlled spiral.As the annular region is square, final attractors of the spiral tip are more abundant, including mainly square attractor, limit circle attractor with small amplitude, diamond attractor and point attractor, where the point attractors are usually on the diagonal lines of the square.Here, trajectory of the spiral tip has a regular change with control parameters of the annual region as well.