Loading...
Association Journal of CSIAM
Supervised by Ministry of Education of PRC
Sponsored by Xi'an Jiaotong University
ISSN 1005-3085  CN 61-1269/O1

Table of Content

    15 April 2024, Volume 41 Issue 2 Previous Issue   
    Research on Weight Adjustment of Sampling Survey of Industrial Enterprises under the Designated Size
    JIANG Tianying, JIN Yongjin
    2024, 41 (2):  199-216.  doi: 10.3969/j.issn.1005-3085.2024.02.001
    Abstract ( 47 )   Save
    In order to solve the problems in the estimation of industrial enterprises under the designated size, the existing weight adjustment range is expanded to improve the estimation accuracy of industrial enterprises under the designated size. On the one hand, it solves the problem of unnatural extinction of catalog enterprises. The unnatural extinction of sample units and the unnatural extinction of sample layer are discussed respectively. The unnatural extinction is regarded as a unit without answer. The sample matching method is introduced to select the most ``similar" normal reporting enterprises to match with the unnatural extinction enterprises, and the weight of the unnatural extinction sample enterprises is adjusted to the normal reporting sample enterprises. On the other hand, the estimation bias of non-catalog enterprises is solved. The weight adjustment ideas based on superpopulation model estimation and inverse weighted estimation of propensity score are discussed, respectively. Linear and nonlinear models are selected for superpopulation model estimation. In the inverse weighted estimation of propensity score, the solution of propensity score is mainly studied. Based on generalized boosted model (GBM) algorithm, weight is introduced in the iterative solution process, and w-GBM algorithm is proposed. At the same time, a combined estimation method is proposed by weighting the logistic regression estimation in the parameter estimation method and the w-GBM algorithm or GBM algorithm in the nonparametric estimation method. The numerical results show that the ideas proposed in this paper are feasible.
    Related Articles | Metrics
    Analysis and Evaluation of the Impact of Tracking Quarantine Measures and Nucleic Acid Test on COVID-19 in Nanjing
    WANG Kai, LI Huixia, LI Yun, ZHAO Hongyong
    2024, 41 (2):  217-231.  doi: 10.3969/j.issn.1005-3085.2024.02.002
    Abstract ( 46 )   Save
    In July 2021, a Corona Virus Disease 2019 (COVID-19) caused by Delta mutant virus broke out in Nanjing. Based on the actual data published by Nanjing Health Commission, we propose a time-dependent COVID-19 epidemic model. Applying the data to estimate the parameters of the model and calculate the effective reproduction number, and then the quarantine and prevention measures and the intensity of nucleic acid test are analyzed and evaluated. The conclusion shows that the intensity of quarantine and nucleic acid test have an important impact on prevention and control of epidemic. The results of this study promote the research on the transmission dynamics modeling and analysis of COVID-19 to a certain extent, and have certain reference significance for dealing with sudden infectious diseases in the future.
    Related Articles | Metrics
    Multi-stage Bayesian Reinforcement Learning Robust Portfolio Selection Model
    LI Roujia, DUAN Qihong, FENG Zhuohang, LIU Jia
    2024, 41 (2):  232-244.  doi: 10.3969/j.issn.1005-3085.2024.02.003
    Abstract ( 76 )   Save
    The estimation of uncertainty sets in traditional multi-stage distributionally robust portfolio selection models is a challenging problem. This paper applys the Bayesian reinforcement learning technique to dynamically update the first two order moments in the uncertainty sets of a multi-stage distributionally robust model. We study the mean-worst case robust CVaR model in the Bayesian reinforcement learning framework. We propose a two-level decomposition solution framework by combining dynamic programming techniques and the progressive hedging algorithm. The lower level finds optimal policies of sub-models with given model parameters by solving a series of second-order cone programming problems. While the upper level finds an implementable policy satisfying non-anticipation constraints by using Bayes'~law. Numerical results in the US stock market illustrate the superior out-of-sample investment performance of the multi-stage Bayesian reinforcement learning robust portfolio selection model.
    Related Articles | Metrics
    Robust Optimal Reinsurance and Investment Strategies for the Insurer and the Reinsurer under Dependent Risk Model
    MU Rui, MA Shixia, ZHANG Xinru
    2024, 41 (2):  245-265.  doi: 10.3969/j.issn.1005-3085.2024.02.004
    Abstract ( 44 )   Save
    This paper studies the optimal reinsurance and investment problem with consideration of joint interests of an insurer and a reinsurer under the risk model with common shock dependence. Suppose that the surplus process of the insurance company and the reinsurance company is described by the diffusion approximation model, and the insurance company can purchase proportional reinsurance whose reinsurance premium is calculated by the mean-variance premium principle to disperse risks. Both insurance companies and reinsurance companies can invest in risk-free assets and risk assets whose price process follows the square-root factor process. By stochastic control theory, we establish the robust Hamilton-Jacobi-Bellman (HJB) equation and obtain the optimal reinsurance-investment strategies and the corresponding value functions under the objective of maximizing the expected utility of the weighted sum of terminal wealth of insurance companies and reinsurance companies. In addition, we give some numerical examples to illustrate the effects of some model parameters on the optimal reinsurance and investment strategies.
    Related Articles | Metrics
    Optimal Investment Strategy of DC Pension Fund with Premium Refund under Inflation and Mispricing
    YIN Yanhong, XIA Dengfeng, FEI Weiyin, GUO Yuchao
    2024, 41 (2):  266-278.  doi: 10.3969/j.issn.1005-3085.2024.02.005
    Abstract ( 37 )   Save
    In this article, we consider the optimal investment problem for a defined contribution (DC) pension plan under the inflation environment and the premium refund clause. We assume that the pension funds are allowed to invest in a risk-free asset and a risky asset with mispricing, for the aim of maximizing the expected utility of the terminal real wealth. Firstly, under the inflation environment, the dynamic equation of the real wealth procession is obtained by using the stochastic Calculus. Secondly, stochastic control theory is used to establish the HJB equation of the real value function of fund manager with the CRRA utility function. Moreover, the analytical solutions of the HJB equation are found. Finally, the impact of inflation volatility, mispricing, risk aversion and premium refund on the optimal strategies are given by numerical simulations. The explain of the economic implications of our theoretical results also be presented.
    Related Articles | Metrics
    A Bi-level Programming Model for OD Demand Reconstruction under Congested Network
    LI Gaoxi, REN Yi
    2024, 41 (2):  279-293.  doi: 10.3969/j.issn.1005-3085.2024.02.006
    Abstract ( 85 )   Save
    A bi-level programming model to reconstruct origin-destination (OD) demand by using density as the observed variable under congested network is proposed. The upper-levels minimize the errors on the estimated values and observed values, and the lower-levels are user equilibrium model. For a bi-level programming model, KKT condition method is adopted, it is transformed into a mathematical program with equilibrium constraints which is easier to solve, and then Scholtes relaxation method is used to solve the transformed model. The numerical results show that, using density as the observed variable is better than using flow in the OD reconstruction problem under congested network. Meanwhile, for solving method of bi-level programming model, the method of transforming KKT condition into single-level is superior to the upper-lower alternate algorithm.
    Related Articles | Metrics
    Penalized Least Squares Method of Partially Linear Spatial Autoregressive Model
    CHENG Yaoyao, LI Tizheng
    2024, 41 (2):  294-310.  doi: 10.3969/j.issn.1005-3085.2024.02.007
    Abstract ( 62 )   Save
    Partially linear spatial autoregressive model has attracted extensive attention in recent years because it combines explanatory power of parametric spatial autoregressive models and flexibility of nonparametric spatial autoregressive model. This paper considers the problem of variable selection in the partially linear spatial autoregressive model. Based on profile quasi-maximum likelihood method and a class of non-convex penalty function, a class of penalized least squares method is proposed to simultaneously select significant explanatory variables in parametric component of the model and estimate corresponding nonzero regression coefficients. Under appropriate regularity conditions, the rate of convergence of the penalized estimator of the regression coefficient vector is derived and it shows that the proposed variable selection method enjoys oracle property. Both simulation studies and real data analysis indicate that the proposed variable selection method has satisfactory finite sample performance.
    Related Articles | Metrics
    Graphic Lattices Having the Closeness of $W$-type Colorings
    ZHANG Mingjun, YANG Jianqing, YAO Bing
    2024, 41 (2):  311-325.  doi: 10.3969/j.issn.1005-3085.2024.02.008
    Abstract ( 53 )   Save
    For deeply investigating topological coding, we define new graph total labelings/total colorings: (set-ordered) odd-edge graceful-difference total labelings/total colorings, twin (set-ordered) odd-edge graceful-difference total labelings/total colorings. We prove two results as follows: If bipartite graph $T$ admits a set-ordered odd-graceful labeling, then the bipartite graph $T^*$ obtained by adding $m$ leaves to $T$ admits an odd-edge graceful-difference total coloring; Each tree admits an odd-edge graceful-difference total coloring. For building randomly graph lattices, we present the algorithm of odd-edge graceful-difference total coloring based on adding randomly leaves and the uniformly $k^*$ graceful-difference algorithm, and make uniformly $k^*$ graceful-difference graph lattices, twin uniformly $(k^*,n^*)$ graceful-difference graph lattices, as well as a graphic lattice is homomorphism to another graphic lattice, called graphic-lattice homomorphism.
    Related Articles | Metrics
    Approximate Controllability of Fractional Impulsive Differential Systems
    PENG Sisi
    2024, 41 (2):  326-340.  doi: 10.3969/j.issn.1005-3085.2024.02.009
    Abstract ( 53 )   Save
    In recent years, the controllability of impulsive differential systems has attracted people's attention, and such systems have been applied in aerospace technology, information science, control system, communication, life science, medicine, economy and other fields. For this reason, the approximation controllability of a class of nonlinear fractional order impulsive differential systems is considered in Banach space. Some achievements have been made on the approximation controllability of semilinear differential systems, but the approximation controllability of impulsive differential systems is more practical significance and generalize the existing theoretical results. Firstly, the existence of the fractional impulsive differential systems mild solution is obtained by using Schauder fixed point theorem. Secondly, the approximation controllability of this type of system is studied by applying the semigroup theory and the relevant properties of the solution operators and the resolution operators. Finally, an example analysis and application is given to illustrate the main results.
    Related Articles | Metrics
    Band Structure Computation of Complex Plasma Photonic Crystals
    LU Xin, KUANG Ying, YANG Jie, WANG Zhijie, WANG Liqun
    2024, 41 (2):  341-364.  doi: 10.3969/j.issn.1005-3085.2024.02.010
    Abstract ( 46 )   Save
    Plasma photonic crystals are composed of plasma and other dielectric materials or vacuum, and have a periodic structure. Their tunable band gap properties enable plasma photonic crystals to be widely used in the manufacture of military medical devices such as filters, plasma cloaks, and plasma lenses. Therefore, it is of great significance to obtain the energy band structure characteristics we need by changing the parameters such as the density and temperature of the plasma. Based on the above considerations, a Petrov-Galerkin finite element method is proposed to solve and analyze the band gap characteristics of plasmonic photonic crystals. The core idea of this method is to construct a basis function space and a test function space whose coefficients are reciprocal of each other on the boundary, and reduce the degree of freedom while eliminating the integral on the boundary. The adopted grid is a semi-Cartesian projected grid, which can adapt to complex plasma column shapes. When the weak form is established, the interface nonlinear continuous condition is linearized, which simplifies the processing of the interface integral term. By drawing the energy band structure diagram of the numerical example, the effects of the plasma electron density, the filling ratio and shape of the plasma photonic crystal column on the band gap width, band gap position, coupling band gap and cut-off frequency are analyzed and verified. Therefore, the controllability of the energy band structure of the plasma photonic crystal can be derived.
    Related Articles | Metrics
    Asymptotic Behaviors and Their Applications of the Bayesian Estimators of Tail Value at Risk on Pareto-Gamma Model
    YAN Jun, CHEN Yunjie
    2024, 41 (2):  365-376.  doi: 10.3969/j.issn.1005-3085.2024.02.011
    Abstract ( 40 )   Save
    The asymptotic behaviors and applications of the Bayesian estimator for the tail value at risk on Pareto-Gamma risk model is helpful to make statistical inference on risk measure, so that venture investors can take corresponding measures to avoid risks in time. Firstly, by constructing Bayesian hypothesis of Pareto-Gamma risk model, the Bayesian estimator for tail value at risk is given, then by using classical large deviation theory, moderate deviation theory and Delta method, the asymptotic behaviors of the Bayesian estimator for tail value at risk is given out, including the asymptotic normality, large deviation principle and moderate deviation principle. Secondly, the specific applications of the moderate deviation principle of the Bayesian estimator for tail value at risk in statistical hypothesis testing are given, and the asymptotic behaviors of the type I error and power function are obtained. Finally, the simulation methods are given to investigate the confidence interval and interval coverage of the tail value at risk, and the standardized histogram and kernel density estimation curve of the Bayesian estimator of tail value at risk are drawn for different sample sizes, which basically coincide with the standard normal distribution density function curve, thus the asymptotic normality of the estimator is verified. At the same time, the stochastic simulation of the tail probability of the tail value at risk is given to show that the tail probability approaches zero at a certain speed when the sample size is sufficiently large, thus the moderate deviation principle of the estimator is verified.
    Related Articles | Metrics
    Research on Due Date Assignment Scheduling Problems with Position-dependent Weights
    LV Danyang, WANG Jibo
    2024, 41 (2):  377-385.  doi: 10.3969/j.issn.1005-3085.2024.02.012
    Abstract ( 55 )   Save
    In this paper, the scheduling problems for due date assignment with position-dependent weights are studied. The goal is to find the optimal job processing sequence in two modes of common/slack due date assignment with the linear weighted sum of minimal due date and tardiness, where the weights are position-dependents weights. By proving a series of properties, the calculation methods of due date are obtained, and then the two kinds of due date assignment problems are transformed into functions related to job processing time. According to coefficient corresponding to each job, the specific solution algorithms are given to obtain the optimal job sequence, and the corresponding optimal common/slack due date. The algorithms are verified to solve the problems in polynomial time by numerical examples.
    Related Articles | Metrics
    A Modified Z-FDTD Based on Inhomogeneous Magnetized Plasma
    ZHANG Jie, HAN Bing, ZHAO Shanchao, ZHANG Guodong
    2024, 41 (2):  386-396.  doi: 10.3969/j.issn.1005-3085.2024.02.013
    Abstract ( 51 )   Save
    A problem about the calculation error of the classical Z-transformation finite difference time domain (Z-FDTD) method in the analysis of the transmission characteristics of electromagnetic wave and non-uniformly magnetized plasma is studied. A modified Z-transform finite difference time domain (MZ-FDTD) method is discussed to improve the applicability of the Z-FDTD method for non-uniformly magnetized plasmas. For the calculation error between MZ-FDTD and Z-FDTD, the calculation formula of the error is derived, and error analysis factor is introduced. The characteristics of the error affected by the spatial step size and the physical characteristics of non-uniformly magnetized plasma are compared and analysed. After sufficient error analysis and mesh parameter comparison, the advantages of MZ-FDTD are illustrated by analysing the propagation characteristics of electromagnetic wave in inhomogeneous magnetized plasma as the objective. The research results show that compared with the classical Z-FDTD, the numerical results obtained by MZ-FDTD method have higher calculation accuracy, lower running time and memory consumption. In addition, the analysis of electromagnetic wave transmission characteristics in non-uniform plasma also proves that compared with Z-FDTD, the numerical results obtained by MZ-FDTD method are relative stability, no matter whether it's in the low band. In the future, using MZ-FDTD method to study the problem of non-uniformly magnetized plasma will get better calculation results, and the error analysis method in this work will also play a helpful role in the application and optimization of some computational electro-magnetics in plasma.
    Related Articles | Metrics