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    Research on the Fuzzy Membership Function Determination Based on Probability Statistics
    Ma Wanyuan, Geng Xiuli
    Mathematical Theory and Applications    2016, 36 (3): 93-100.  
    Abstract1219)      PDF(pc) (682KB)(706)      
    The key of using fuzzy mathematics to solve practical problems is to establish realistic membership function.The commonly used method to compute the fuzzy membership function is fuzzy statistic method, which relies on a large number of survey data and analysis on the function graph,and the calculation with heavy workload and complex process limits the practical application of fuzzy technology.A method for determining the fuzzy membership function based on probability statistics is proposed from the view of statistics.The proposed method is relatively simple and can adapt to much more cases of fuzzy membership function determination. Finally,a real world case is given and membership function curves derived from two methods are compared to verify the proposed method having higher accuracy.
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    Numerical Simulation Algorithms for Stochastic Differential Equations in Systems Biology
    Niu Yuanling, Chen Lin, Chen luonan
    Mathematical Theory and Applications    2023, 43 (4): 76-92.   DOI: 10.3969/j.issn.1006-8074.2023.04.005
    Abstract616)      PDF(pc) (508KB)(336)      
    Many phenomena in systems biology, such as the biochemical reaction process, the evolution of ecosystems, the spread of infectious diseases, can be described by stochastic differential equations (SDEs). Considering the influence of randomness, stochastic differential equation models can describe the evolution of variables over time more accurately than deterministic differential equation models. However, the analytical solutions of most stochastic differential equations cannot be obtained. Even though some of them can be obtained, the forms of the solutions are usually extremely complex. One therefore requires proper numerical methods to approximate their solutions on computers. These stochastic differential equation models in systems biology usually have the properties of high dimension, high nonlinearity, and the solutions being located in a specified region. It is difficult to simulate them numerically. This paper reviews the numerical simulation algorithms of several typical models in systems biology (biochemical reaction models, ecosystem models, infectious disease models, population genetics models, cell differentiation models), and briefly introduces their advantages and disadvantages.
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    Investigation and Analysis on WeChat Payments Among College Students in Changsha City

    Chen Jing, Gu Xiaoxiao, Zhu Enwen
    Mathematical Theory and Applications    2016, 36 (4): 81-91.  
    Abstract1306)      PDF(pc) (2110KB)(276)      

    With the rise of e-commerce in the internet era,the online shopping has become a new consumer trend.With the rapid development of WeChat in the past few years,WeChat payments have greatly changed the pattern of Alipay or other third-party payment  platform monopoly market.In nowdays,college students as one of the main groups of WeChat payment and third-party payment will affect the future of WeChat's development to a large extent.A sampling survey via distributing questionnaire to college students in Changsha city is carried.Sample data are analyzed with the statistical software SPSS and Excel,and some suggestions are

    given based on the results from the data.
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    Prediction of Active Value of Anti-breast Cancer Drug Candidates Based on GA-BP Neural Network Model
    Shang Yaxin , Lei Xiaojie, Fang Ziniu , Zhang Hongwei
    Mathematical Theory and Applications    2024, 44 (2): 103-125.   DOI: 10.3969/j.issn.1006-8074.2024.02.008
    Abstract350)      PDF(pc) (2097KB)(99)      
    Screening for anti-breast cancer drug candidates is of great significance in the treatment of breast cancer. Antihormonal therapy for breast cancer is often used in breast cancer patients with ERα expression, and the higher the anti-ERα activity value, the more effective the drug is for treatment. In this paper, 729 molecular descriptors of the compound are filtered firstly using the gradient boost model XGBoost and the distance correlation coefficient matrix, then based on the filtered 20 molecular descriptors with their activity values and the genetic algorithm, a GA-BP neural network model is established, which has a mean squared error MSE=0. 105 and a coefficient of determination $\mathrm{R}^2=0. 946$, and therefore is a high-precision model for screening potential drugs based on data mining techniques. 
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    Lp-convergence Rate of the Tamed Euler Scheme for SDEs with Piecewise Continuous Drift Coefficient
    Hu Huimin, Gan Siqing
    Mathematical Theory and Applications    2024, 44 (2): 1-19.   DOI: 10.3969/j.issn.1006-8074.2024.02.001
    Abstract832)      PDF(pc) (214KB)(110)      

    In this paper we study the $L^p$-convergence rate of the tamed Euler scheme for scalar stochastic differential equations (SDEs) with piecewise continuous drift coefficient. More precisely, under the assumptions that the drift coefficient is piecewise continuous and polynomially growing and that the diffusion coefficient is Lipschitz continuous and non-zero at the discontinuity points of the drift coefficient, we show that the SDE has a unique strong solution and the $L^p$-convergence order of the tamed Euler scheme is at least 1/2 for all $p \in [1,\infty)$. Moreover, a numerical example is provided to support our conclusion.

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    Multiple Solutions for Nonhomogeneous Kirchhoff-Schrödinger-Poisson System with  p-Laplacian
    Wang Mei, Suo Hongmin, Zhang Xuemei, Wang Chenxi
    Mathematical Theory and Applications    2024, 44 (2): 20-35.   DOI: 10.3969/j.issn.1006-8074.2024.02.002
    Abstract357)      PDF(pc) (192KB)(125)      

    In this paper we consider the existence of solutions to the nonhomogeneous quasilinear Kirchhoff- Schr\"{o}dinger-Poisson system with $ p $-Laplacian:

    \begin{equation*}\label{1ip}

    \begin{cases}\displaystyle

    - \Big(a-b \int_{\mathbb{R}^3}|\nabla u|^p{\rm d}x \Big)\Delta_p u+|u|^{p-2}u+\lambda\phi_uu= |u|^{q-2}u+h(x), &\text{ }x\in \mathbb{R}^3,\\

    -\Delta\phi=u^2, &\text{ }x\in \mathbb{R}^3,\\

    \end{cases}

    \end{equation*}

    where $ a,b>0 $, $ \frac{4}{3} < p < \frac{12}{5} $, $ p < q < p^* =\frac{3p}{3-p} $, $ \lambda > 0 $. Under suitable assumptions on $ h(x) $, the existence of multiple solutions of the system is obtained by using the Ekeland variational principle and the Mountain pass theorem.

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    Construction of Cross-border E-commerce Development Indices and Empirical Analysis
    Mathematical Theory and Applications    2019, 39 (3-4): 113-120.  
    Abstract783)      PDF(pc) (713KB)(827)      
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    Numerical Simulation of the Generalized Fractional Allen - Cahn Phase FielS Equations
    Mathematical Theory and Applications   
    Online available: 05 March 2021

    Progress in Spatio­temporal Dynamics of Vegetation Systems
    Zhang Hongtao, Sun Guiquan
    Mathematical Theory and Applications    2023, 43 (2): 1-15.   DOI: 10.3969/j.issn.1006­8074.2023.02.001
    Abstract1193)      PDF(pc) (509KB)(281)      
    Vegetation pattern is one of the typical characteristics of ecosystems in arid and semi­arid areas, which can qualitatively describe the spatial distribution structure of vegetation, and can be used as an early indicator of ecosystem improvement and degradation. This paper devotes to summarize the bifurcation phenomena in vegetation system to reveal the formation mechanism of vegetation pattern and provide warning signals of desertification. Firstly, through the Hopf bifurcation theory, the conditions of spatial homogeneous Hopf bifurcation in vegetation model are qualitatively analyzed, and the phenomenon of interannual periodic fluctuation of vegetation biomass is explained. Secondly, the existing vegetation models are analyzed by the Turing bifurcation theory, the regular distribution of
    vegetation in space and the formation mechanism of pattern are revealed, and the types of these patterns are refined by applying the multiple scale analysis method, and the parameter threshold of the system undergoing pattern phase transition is found. Finally, when the Hopf bifurcation and Turing bifurcation occur at the same time, the system will undergo a Turing-­Hopf bifurcation. By means of the normal form theory of reaction­diffusion equation, the normal form of the Turing­-Hopf bifurcation is derived, and the amplitude equation is obtained by the cylindrical coordinate  transformation to analyze its dynamic behavior, and then more complex spatiotemporal patterns of vegetation are revealed.
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    A Mathematical Model for Parameter-Calibration and Imaging of CT System
    Yang Yunxia
    Mathematical Theory and Applications    2017, 37 (3-4): 115-121.  
    Abstract1359)      PDF(pc) (3704KB)(718)      
    Abstract In this paper,firstly,by fitting the CT scan received information with the MATLAB software,a  series of images about the parameter-calibration and imaging of a CT system are obtained.And then,based on the received information and the obtained images,a mathematical model is established for the parameter-calibration and imaging of the CT system.
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    Quantitative Trading Strategies of Shanghai and Shenzhen 300Index Futures Based on SVM
    Zhang Jian, Wang Bo
    Mathematical Theory and Applications    2017, 37 (2): 112-121.  
    Abstract1422)      PDF(pc) (1789KB)(722)      
    Based on the theory of support vector machine,aquantitative trading model of Shanghai and Shenzhen 300 stock index futures is established.Differing from the regression forecasting method,the model firstly makes use of the advantage of support vector machine in classification in nonlinear systems to transform a complex time series regression prediction problem into a two classification problem by converting the price evolution trend into a transaction signal,and then takes the price information and technical indicators as the input vector,introduces the stop-loss mechanism and obtains the quantitative trading strategy upon the dynamic forecasting model.Empirical results show that the price information transaction strategy has better performance than the technical index trading strategy,and overall,the quantitative trading model has achieved good profit effect.
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    Existence of Distinct Positive Integer Solutions to a Generalized Form of Erdös-Straus Conjecture
    You Lihua, Li Jiayin, Yuan Pingzhi
    Mathematical Theory and Applications    2024, 44 (2): 65-79.   DOI: 10.3969/j.issn.1006-8074.2024.02.005
    Abstract339)      PDF(pc) (192KB)(85)      

    In this paper, we study the (distinct) positive integer solution of the equation

    \begin{equation*}\label{eq12}\frac{k}{n} = \frac{1}{x_1}+\frac{1}{x_2}+\cdots+\frac{1}{x_t}\end{equation*} with $n>k\geq 2$ and $ t\geq 2$.

    We show that the above equation has at least one distinct positive integer solution if it has a positive integer solution.

    When $k=5$, we show the above equation has at least one distinct positive integer solution for all $n\geq 3$

    except possibly when $n\equiv 1, 5041, 6301, 8821, 13861, 15121(\mbox{mod } 16380)$ with $t=3$,

    and for all $n\geq 3$ except possibly when $n\equiv 1, 81901(\mbox{mod } 163800)$ with $t=4$.

    Furthermore, we point out that the above equation has at least one distinct positive integer solution for all $n(>k)$

    when $t\geq k\geq 2$.

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    Genus of Cartesian Product of a Complete Regular Tripartite Graph and a Bipartite Graph
    Guo Ting
    Mathematical Theory and Applications    2024, 44 (2): 92-102.   DOI: 10.3969/j.issn.1006-8074.2024.02.007
    Abstract336)      PDF(pc) (208KB)(88)      
    Let $K_{m,m,m}$ ($m\geq1$) be a complete regular tripartite graph, and $G$ be a bipartite graph with girth greater than 4. In this paper, the genus of cartesian product of $K_{m,m,m}$ and $G$ with $\Delta(G)\leq 2m$ is determined. It generalizes the result by Bonnington and Pisanski, which gives the genus of cartesian product of $K_{m,m,m}$ and an even cycle. Moreover, the nonorientable genera of cartesian products of $K_{m,m,m}$ and some non-bipartite graphs are obtained.
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    Entry Timing and Product Differentiation Decision in Continuous Time Circular City Model
    Zhang Bo, Hu Zhijun
    Mathematical Theory and Applications    2022, 42 (3): 114-.   DOI: 10.3969/j.issn.1006-8074.2022.03.009
    Abstract1418)      PDF(pc) (310KB)(915)      
    This paper investigates enterprises' decision of the location, pricing and entry timing with asymmetric investment costs in a circular city. Using the option game theory, we construct the dynamic game model of duopoly enterprises with horizontal product differentiation in the circular market, analyze the existing sequential equilibrium and preemptive investment equilibrium, and depict the sub-game perfect equilibrium of the dynamic game under the Stackelberg Equilibrium. The study shows that the profit of enterprises increase with the increase of product differentiation; the enterprise with cost advantage always enters the market as a leader; when the cost asymmetry of two enterprises is less than the critical value, the leader's entry timing is controlled by the threat of preemption, and the leader's profits brought by cost advantage will be damaged; the entry timing of the follower is not affected by the degree of cost asymmetry.
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    Normalized Solutions for a Class of Kirchhoff Equations
    Liang Yanxia
    Mathematical Theory and Applications    2024, 44 (2): 36-50.   DOI: 10.3969/j.issn.1006-8074.2024.02.003
    Abstract328)      PDF(pc) (180KB)(109)      
    In this paper we study the existence of normalized solutions to a class of Kirchhoff equations with the variational method, and obtain the normalized ground state solutions when $\mu>0$, and the local minimizers and the mountain pass type critical points for the energy functionals when $\mu<0$.
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    Solvabilities of Interval Linear Inequalities over Max-min Algebra
    Li Haohao, Wang Lulu, Jia Shengnan
    Mathematical Theory and Applications    2024, 44 (2): 51-64.   DOI: 10.3969/j.issn.1006-8074.2024.02.004
    Abstract319)      PDF(pc) (165KB)(83)      
    The characteristics of interval systems under the framework of extremum algebra is a meaningful research direction. In this paper we study the characterizations of various kinds of solvabilities of interval linear inequalities in the max-min algebra, including the weak solvability, strong solvability, tolerance solvability, strongly tolerance solvability, control solvability and strongly control solvability. Furthermore, we analyze the existence of solutions and the solvabilities, and show these two concepts are equivalent in certain situations. In addition, we find the maximum solutions corresponding to different kinds of solvabilities.
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    Image Denoising Algorithm Based on Total Variation
    Ni Nianyong, Sun Bo
    Mathematical Theory and Applications    2017, 37 (2): 32-37.  
    Abstract1374)      PDF(pc) (564KB)(683)      

    In this paper we study the image denoising algorithm based on total variation.The corresponding optimization model is solved by the steepest descend method,the difference iterative method and the split Bregman method,respectively.Experiment results show that the difference iterative method convergences rapidly,and achieves better denoising performances.

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    Quasi-Monte Carlo Method for a Class of Stochastic Optimal Control Problems
    Zhou Hongmin, Luo Xianbing, Ye Changlun
    Mathematical Theory and Applications    2022, 42 (3): 71-.   DOI: 10.3969/j.issn.1006-8074.2022.03.006
    Abstract1562)      PDF(pc) (305KB)(803)      
    In this paper, a gradient projection optimization method is applied to solve a class of stochastic optimal control problems. The Monte Carlo method is a common method to deal with stochastic optimal control problems, but it has a notoriously slow convergence rate. We choose the Quasi-Monte Carlo method with faster convergence.  In order to make the random sampling dimensions and time discrete points independent, we use the Karhunen-Lo${\grave{\rm e}}$ve truncation for the Brown motion. Sobol sequences of  the Quasi-Monte Carlo method are used for sampling. The error of numerical approximation is presented, and the effectiveness of the method is verified by numerical experiments.
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    Block-transitive Automorphism Groups of 3- (v,7,λ) Designs
    Chen Shihan, Dai Shaojun, Zhao Kun
    Mathematical Theory and Applications    2024, 44 (2): 80-91.   DOI: 10.3969/j.issn.1006-8074.2024.02.006
    Abstract336)      PDF(pc) (162KB)(83)      

    Let ${\cal S}$=$({\cal P},{\cal B})$

    be a nontrivial $3$-$(v,7,\lambda)$ design with $\lambda\geq 2$. In this paper we show that if $G$ is a block-transitive automorphism group of $\cal S$, then $G$ is point-primitive of affine

    or almost simple type. In addition, the case that $G$ is a finite almost simple group with an alternating group socle $A_n$ is considered as well.

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    Derivation Algebra and Automorphism Group of the Mirror Heisenberg-Virasoro Algebra
    Zhao Yufang, Cheng Yongsheng
    Mathematical Theory and Applications    2022, 42 (4): 36-.   DOI: 10.3969/j.issn.1006-8074.2022.04.003
    Abstract1598)      PDF(pc) (175KB)(346)      
    In this paper, we study the derivation algebra and automorphism group of the mirror Heisenberg-Virasoro algebra, determine the outer derivation and the first cohomology group of the mirror Heisenberg-Virasoro algebra with the coefficients in itself.
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