Table of Content

15 December 2021, Volume 38 Issue 6 Previous Issue   

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Semi-automatic Text Category Labelling Method Based on Machine Learning GONG Yansheng, CAI Keping, WANG Zhiqiang, LI Xinxin, JING Wenfeng 2021, 38 (6):  750-762.  doi: 10.3969/j.issn.1005-3085.2021.06.001 Abstract ( 123 )   PDF (356KB) ( 273 )   Save In the text classification problem, the efficiency of manual labelling is very low, and professionals familiar with the research field are needed to carry out this work. In order to improve the efficiency of text data labelling, a semi-automatic paper category labelling method is proposed. Firstly, the vector representation of paper abstracts is derived by the combination of word2vec and TF-IDF; then the K-means algorithm is used to complete text clustering; K classification models are constructed through the $L_1$-LR binary classification model; For each binary classification model, the word corresponding to the coefficient with large absolute weight value is selected as the subject word. Finally, the label of each category is determined according to the subject word. The proposed semi-automatic paper category labelling method greatly improves the efficiency of text labelling. Related Articles | Metrics

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Capacity Sharing Strategies under Carbon-emission-trading Mechanism Considering Consumer's Low-carbon Preference WU Anbo, WU Yuxiu, SUN Linhui 2021, 38 (6):  763-777.  doi: 10.3969/j.issn.1005-3085.2021.06.002 Abstract ( 97 )   PDF (512KB) ( 118 )   Save Under the green manufacturing environment with the low-carbon emission purpose, the contradiction between idle capacity resources and shortage has become one of the critical problems in the operation of manufacturing enterprises. It is vital to realize capacity sharing and to improve the utilization rate of resources. A game model is utilized in this paper to explore the impact of Carbon-emission-trading on manufacturers' capacity sharing strategies. We consider two competitive manufacturers with sufficient capacity and insufficient capacity as the research setting and study the optimal decision problem of manufacturers' capacity sharing under consumer's preference for low-carbon products. At the same time, we verify the model by numerical simulations. The results show that the amount of capacity transferred and the transferring price per unit product are negatively correlated with the emission reduction level of the manufacturer with sufficient capacity. In contrast, the amount of capacity transferred is positively correlated with the emission reduction level of the manufacturer with insufficient capacity. When the carbon emission reduction level of the two manufacturers is within a specific range, the profits of both manufacturers will increase. Related Articles | Metrics

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Optimal Asset Allocation for a DC Pension Fund in the Market with Multiple Dependent Risky Assets SUN Jingyun, GUO Jingjun, ZHAO Yu 2021, 38 (6):  778-796.  doi: 10.3969/j.issn.1005-3085.2021.06.003 Abstract ( 67 )   PDF (288KB) ( 77 )   Save We consider an optimal asset allocation problem for a defined contribution pension fund in the accumulation phase before the participant retired. It is assumed that the prices of $n$ risky assets suffer a common jump phenomenon because of the impact of market systematic risk. So the prices of the risky assets are modeled with dependent jump-diffusion processes. In addition, we suppose that the income process of the participant satisfies a jump-diffusion process before she retired. To minimize the expected square loss between the pension fund account and the expected investment target at the time of retirement, the stochastic dynamic programming method is adopted, and the closed-forms of the optimal investment strategy and the value function are obtained, a verification theorem and its proof are also provided. Finally, through some numerical examples, we find that the jump parameters in the price process of risky asset and participants' income process, the earnings preference of pension fund managers and the expected investment objective process all have significant influence on the optimal investment strategy and the value function. Related Articles | Metrics

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Hesitant Pythagorean Fuzzy Multi-attribute Decision-making Method Based on DEMATEL and VIKOR YANG Wei, LIU Chunxin 2021, 38 (6):  797-808.  doi: 10.3969/j.issn.1005-3085.2021.06.004 Abstract ( 63 )   PDF (209KB) ( 92 )   Save Aiming at the multi-attribute decision-making problem in complex fuzzy uncertain environment, a hesitant Pythagorean fuzzy multiple attribute decision making method based on DEMATEL and VIKOR is proposed. First, the attribute weight is determined by the DEMATEL method, and alternatives are ranked by the VIKOR method. Secondly, for the cases where ranking results are inconsistent, the Kendall-W coefficient is used to perform the ex-ante consistency check. Then a combined fuzzy Borda method is proposed. Spearman coefficient is used to perform the ex-post consistency check, and a combined fuzzy Borda method is proposed. Finally, the feasibility and effectiveness of the proposed method are illustrated by an example. Related Articles | Metrics

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Research on the Dynamic Relationship between PPI and 10-year Treasury Bond Yield in the New Normal Period YUAN Weipeng, ZHANG Yi, ZHANG Fei, YANG Weiming 2021, 38 (6):  809-821.  doi: 10.3969/j.issn.1005-3085.2021.06.005 Abstract ( 88 )   PDF (674KB) ( 152 )   Save A vector autoregressive (VAR) model is constructed based on the data of industrial producer price index (PPI) and 10-year treasury bond yield. By analyzing the results of the Granger causality test, impulse response, and analysis of variance decomposition, the qualitative and quantitative relationship between China's PPI and the 10-year treasury bond yield is systematically examined. The result of causality test reveals that PPI is the Granger cause of 10-year treasury bond yield, but the 10-year treasury bond yield is not the Granger cause of PPI, thus indicating that PPI has a predictive effect on the trend of 10-year treasury bond yield. Furthermore, the impulse response analysis shows that PPI has a positive effect on the 10-year treasury bond yield. At last, the method for PPI forecast is given, which provides a reference for determining the trend of the 10-year treasury bond yield and bond investment. Related Articles | Metrics

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Distributivity of T-power Implications Over t-norms and t-conorms FU Yijia, ZHOU Hongjun 2021, 38 (6):  822-844.  doi: 10.3969/j.issn.1005-3085.2021.06.006 Abstract ( 57 )   PDF (246KB) ( 124 )   Save Distributivity equations of fuzzy implications over triangular norms and triangular conorms play an important role in approximate reasoning, especially in fuzzy reasoning and control. A great deal of researches have been done on the distributivity equations of fuzzy implications over triangular norms and triangular conorms. Recently, Massanet et al. proposed a new kind of fuzzy implications based on powers of continuous t-norms, called T-power based implications and made an in-depth study of its properties. To extend the knowledge system of T-power implications and distributivity equations of fuzzy implications over triangular norms and triangular conorms, the paper studies four distributivity equations of T-power implications over triangular norms and triangular conorms. Necessary and sufficient conditions for the four distributivity equations of T-power implications over triangular norms and triangular conorms are given. This paper also points out that T-power implications are different from other well-known classes of fuzzy implications, and improves finally the knowledge framework of fuzzy implications. Related Articles | Metrics

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Nonlinear Mixed Finite Element Method for Coupled Two-phase Flow and Geomechanics Problem in Porous Media LIU Ziping, LI Junxiang, LIU Qi, MA Qiang, WEI Huayi 2021, 38 (6):  845-855.  doi: 10.3969/j.issn.1005-3085.2021.06.007 Abstract ( 79 )   PDF (2995KB) ( 231 )   Save A fully coupled two-phase flow and geomechanics in a reservoir system is considered. The governing equation is derived in terms of the saturation, pressure, velocity for the flow and displacement for the structure. A nonlinear computational scheme is constructed by incorporating the mixed finite element with the conforming element, and the corresponding finite element procedure is proposed, which guarantees the local conservation of mass within the element. The effectiveness and correctness are verified by performing the numerical experiment for the water flooding in a homogeneous reservoir. Moreover, the water flooding in a heterogeneous reservoir with cross fracture is simulated and the high resolution of saturation solution is obtained, showing that the complex multiphysics of the reservoir system can be well captured by the proposed method. Related Articles | Metrics

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Numerical Method for Modified Kernel to Solve the Cauchy Problem of Three-dimensional Helmholtz-type Equation HE Shangqin, FENG Xiufang 2021, 38 (6):  856-868.  doi: 10.3969/j.issn.1005-3085.2021.06.008 Abstract ( 52 )   PDF (4703KB) ( 85 )   Save In order to solve the severely ill-posed Cauchy problem of 3D Helmholtz-type equation, a modified kernel method based on exact solution is proposed. By constructing a mollification operator, the ill-posed problem is transformed into a well-posed problem, and stable numerical approximation solutions are obtained. When the wave-number $k$ and parameter $m$ meet the necessary conditions, the error estimates between the regularization approximation solution and exact solution are given in terms of $L^2$-estimate and $H^s$-estimate under the suitable choices of the regularization parameter. The theoretical part is verified by numerical examples. The results show that the proposed regularization method is stable and effective. Related Articles | Metrics

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A Moving Mesh Method for Two Dimensional Parabolic Singularly Perturbed Problems ZHOU Qin 2021, 38 (6):  869-878.  doi: 10.3969/j.issn.1005-3085.2021.06.009 Abstract ( 51 )   PDF (594KB) ( 86 )   Save Singular perturbation problems have been applied in various areas of mechanics, acoustics, optics, engineering and others. A class of two-dimensional parabolic singular perturbation problem with source terms is considered. The numerical scheme of the problem on spatial moving meshes is constructed by means of coordinate transformation and finite volume method. The mesh iteration method and updating method of solution on moving mesh are given, and an adaptive moving mesh algorithm with local refinement is proposed. The numerical results show that, compared with the solution on uniform mesh, the adaptive moving mesh method can reflect the local characteristics of the solution better and has better solution accuracy. Related Articles | Metrics

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A New Efficient Numerical Method for Pricing American Options on Zero-coupon Bonds GAN Xiaoting, YI Hua 2021, 38 (6):  879-900.  doi: 10.3969/j.issn.1005-3085.2021.06.010 Abstract ( 74 )   PDF (1224KB) ( 147 )   Save Unlike the European options pricing, the closed-form solution generally does not exist due to the early exercise feature of American options. Hence, numerical approximation methods are normally employed to solve them. Presented in this paper is a new numerical method to price American bond options. To numerically solve the resulting partial differential complementarity problem (PDCP), we develop a class of finite volume method for the spatial discretization, coupled with the stable fully implicit time stepping scheme of the partial differential equation (PDE). Then, the resulting linear complementarity problems (LCPs) are solved by using an efficient iterative method, the modulus-based matrix splitting iteration method, where the $H_{+}$-matrix property of the system matrix guarantees its convergence. Numerical experiments are implemented to verify the accuracy, efficiency and robustness of the new method. Related Articles | Metrics