Table of Content

  

20 January 2020
Volume 55 Issue 1

Armendariz property for a group ring over the Hamiltons quaternion ring

YANG Liu, MA Jing

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  1-4.  doi:10.6040/j.issn.1671-9352.0.2019.127

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The Armendariz property of group rings is discussed. It is proved that the group ring HC_n is an Armendariz ring if and only if n≤2, where C_n is a cyclic group with n elements; for a torsion group T, an equivalent condition is given for the group ring HT to be an Armendariz ring. As an application, for real polynomial f(x)of degree n, it is proved that the quotient ring H［x］/(f(x))is an Armendariz ring if and only if f(x)has n real roots(counting multiplicity).

Complete moment convergence and complete integral convergence for END random variables

ZHANG Ya-jing, TAO Hui-ling, LI Xiang, SHEN Ai-ting

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  5-11.  doi:10.6040/j.issn.1671-9352.0.2018.449

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Let {X,X_n,n≥1} be a sequence of extended negatively dependent(END)random variables with identical distribution, and S_n=∑ⁿ_i=1X_i, n≥1. The equivalent conditions between complete moment convergence ∑^∞_n=1n^r-2-1/(pq)a_nE(max1≤k≤n|S_k|1/q-εb_n1/(pq))⁺<∞, ∠ε>0and complete integral convergence were investigated under two cases: r>1, q>0, 0<p<2, a_n=1, b_n=n and p=2, a_n=(log n)^-1/(2q), b_n=n log n. The results obtained generalize the corresponding ones for negatively associated(NA)random variables and negatively orthant dependent(NOD)random variables.

Stochastic model of heroin drug dissemination with psychological effects

FANG Shu, ZHANG Tai-lei, LI Zhi-min

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  12-22.  doi:10.6040/j.issn.1671-9352.0.2019.040

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In this paper, considering the relapse of heroin addicts, we establish a stochastic model with psychological effects for the transmission of heroin drugs. The existence of global unique positive solutions of the model is proved by using stopping time theory. When the basic reproduction number of the corresponding deterministic model is equal or less than 1, the heroin-free propagation equilibrium point of the stochastic model is globally randomly asymptotically stable. It shows that the solutions of the stochastic model oscillates near the corresponding deterministic model heroin propagation equilibrium point when the basic reproduction number of the deterministic model is greater than 1. Sufficient conditions are obtained for the average persistence of solutions and the extinction of drugs. Finally, the numerical simulation further shows the dynamic behavior of the model.

A priori error estimates of finite element methods for an optimal control problem governed by a one-prey and one-predator model

ZHENG Rui-rui, SUN Tong-jun

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  23-32.  doi:10.6040/j.issn.1671-9352.0.2019.069

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An optimal control problem governed by a one-prey and one-predator model is considered. The co-state equations and optimality conditions are established using optimal control theory. In order to construct the fully discrete approximation, the state and co-state variables are approximated by piecewise linear continuous functions and the control variable is approximated by piecewise constant functions. A priori error estimates for the state variables, co-state variables and control variable are proved.

Algebraic structures of generalized Pythagorean fuzzy soft set

ZHANG Hai-dong, Jia-hua Duojie, HE Yan-ping

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  33-40.  doi:10.6040/j.issn.1671-9352.4.2019.121

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The Pythagorean fuzzy soft set theory is generalized and the concept of the generalized Pythagorean fuzzy soft set is introduced. In order to establish the theoretical basis for the generalized Pythagorean fuzzy soft set, we define some operation operators of the model, and discuss its lattice structures. First, three lattice structures of the generalized Pythagorean fuzzy soft set are constructed. Then it is also proved that the three lattice structures are soft algebraic structures. Finally, we explore three complemented distributive lattices which are also called Boolean lattices.

Knowledge acquisition of multi-source data based on multigranularity

WAN Qing, MA Ying-cang, WEI Ling

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  41-50.  doi:10.6040/j.issn.1671-9352.1.2019.105

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Multigranularity cognition is the common strategy for analyzing complex data. Multi-source data is one type of the complex data, and its knowledge acquisition become more complicated because of its multisource. Inspired by the idea of multigranularity, the multi-source attribute reduction is defined based on the pessimistic decision-making strategy in multi-source information systems. The relationships between the multi-source attribute reduction and the attribute reduction are discussed in detail, and the corresponding judgment method of attribute characteristics are given. Finally, the definition of multi-source decision rule is proposed based on the optimistic decision-making strategy in multi-source decision information systems. On the basis of multi-granularity model, the proposed method gives a new perspective of multi-source data analysis, which enriches the study of knowledge acquisition.

Incremental method for approximating sets of multi-granularity rough sets

ZHANG Hai-yang, MA Zhou-ming, YU Pei-qiu, LIN Meng-lei, LI Jin-jin

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  51-61.  doi:10.6040/j.issn.1671-9352.1.2019.167

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Dynamic updating the upper and lower approximations in multi-granulation rough sets based on column matrix mainly use the relative correct classification rate to consider the varying attribute values and varying universe simultaneously. First, we discuss some properties of upper and lower approximation operators of multi-granulation rough sets while the universe decreasing and adding attributes, and give an updating method for approximations based on column matrix. Second, we discuss some properties of approximation operators while the universe decreasing and adding attributes, and give an updating method based on column matrix. The methods we proposed effectively shrink the searching region when updating the approximations of the multi-granulation rough sets.

An incremental attribute reduction approach when attribute values and attributes of the decision system change dynamically

JING Yun-ge, JING Luo-xi, WANG Bao-li, CHENG Ni

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  62-68.  doi:10.6040/j.issn.1671-9352.1.2019.006

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The incremental mechanisms to calculate relative knowledge granularity based on matrices are introduced when multiple attributes are added into decision system and attribute values refining. Then, the corresponding incremental attribute reduction method based on matrix is developed. Compared with the non-incremental attribute reduction algorithm and other incremental algorithms, the proposed incremental attribute reduction algorithm based on matrix can obtain a new reduct in a much shorter time. Finally, experiments on some data sets downloaded from UCI show that the proposed incremental attribute reduction method based on matrix is effective and efficient.

Pricing strategy of vehicles and cargos matching platform in the sharing economy

Yun-miao GUI,Zhong WU,Hong-chun HU

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  69-76,85.  doi:10.6040/j.issn.1671-9352.0.2019.001

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In order to improve the competitive advantage and performance of the vehicles and cargos matching platform, the article analyzes the characteristic of service providers of vehicles and cargos matching platform. By dividing it into professional and non-professional service providers, a game model of the vehicles and cargos matching platform is constructed. The result show that, if platforms' two sides are single-homing, the vehicles and cargos matching platform would charges the same fee for two kinds of suppliers, but if platforms' one side is multi-homing, the vehicles and cargos matching platform tend to charge high access price for non-specialist suppliers and lower access price for professional suppliers. Moreover, a strategy of accessing to suppliers firstly would be more beneficial to the oligopoly vehicles and cargos matching platform.

 

Ambidextrous innovation of brand community members' resource endowment

Wen-yuan MA,Qiu-tong LI,Yao-yao ZHANG,Jin ZHU

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  77-85.  doi:10.6040/j.issn.1671-9352.0.2019.596

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Based on the ability-motivation-opportunity (AMO) theory, the mechanism of ambidextrous innovation motivation of brand community members were studied using structural equation modeling. The moderating role of community commitment to the innovation processes was explored. It was found that (1) brand knowledge positively influences the exploitative innovation, while social capital has a positive impact on exploratory innovation; (2) the community innovation opportunity partially mediates the negative influence of members' brand knowledge on exploitative innovation and positive influences of members' social capital on exploratory innovation; (3)member's community commitment negatively moderates the influence of community innovation opportunities to the exploitative innovation.

Evolutionary game analysis of dual-channel supply chain considering service quality and delay decision

Feng-shan SI,Jing WANG,Dao-ming DAI

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  86-93, 101.  doi:10.6040/j.issn.1671-9352.0.2018.260

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Considering the retailer's service quality and delay decision, this paper constructs a delay differential price game model for dual-channel supply chain, explores the existence and local asymptotic stability of Hopf bifurcation in the game model, analyses the influence of decision variables on the stability of the game model, and explores the influence of the stability of the system on the price evolution trend. The results show that the equilibrium strategy of the stabilization system remains unchanged if delayed decision is adopted or not; the game results of the stabilization system converge to the equilibrium strategy, while the game results of the unstable system tend to the limit cycle; the delay decision variables, service quality and price adjustment speed must be adjusted within a certain range to maintain the stability of the system; and the unstable system can be successfully controlled.

Topic tag popularity prediction based on multi-dimensional features

Xin-le WANG,Wen-feng YANG,Hua-ming LIAO,Yong-qing WANG,Yue LIU,Xiao-ming YU,Xue-qi CHENG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  94-101.  doi:10.6040/j.issn.1671-9352.1.2018.136

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The characteristics of user network structure information and topic tags such as sentiment and regionality are analyzed. A popularity prediction model that considers the user's fan network structure characteristics and the subject tag's own characteristics is proposed. Experiments have proved that the newly proposed feature is effective and has a high reference value for predicting the popularity of future topic tags.

BERT-IDCNN-CRF for named entity recognition in Chinese

Ni LI,Huan-mei GUAN,Piao YANG,Wen-yong DONG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  102-109.  doi:10.6040/j.issn.1671-9352.2.2019.076

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The pre-trained language model, BERT (bidirectional encoder representations from transformers), has shown promising result in NER (named entity recognition) due to its ability to represent rich syntactic, grammatical information in sentences and the polysemy of words. However, most existing BERT fine-tuning based models need to update lots of model parameters, facing with expensive time cost at both training and testing phases. To handle this problem, this work presents a novel BERT based language model for Chinese NER, named BERT-IDCNN-CRF (BERT-iterated dilated convolutional neural network-conditional random field). The proposed model utilizes traditional BERT model to obtain the context representation of the word as the input of IDCNN-CRF. At training phase, the model parameters of BERT in the proposed model remain unchanged so that the proposed model can reduce parameters training while maintaining polysemy of words. Experimental results show that the proposed model obtains significant training time with acceptable test error.

Relationship between plant diversity and ecosystem multifunctionality in the Yellow River Delta

Wen-xin ZHANG,Xiao-li FAN,Qiang WANG,Yong FANG,Yu LIANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  110-116.  doi:10.6040/j.issn.1671-9352.0.2019.786

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The Yellow River Delta is selected as the study area and the relationship between plant diversity and ecosystem multifunctionality is explored. The species richness, Shannon index and Simpson index are positively related to ecosystem multifunctionality, but species richness has a larger effect than Shannon index and Simpson index. High biodiversity has been shown to be especially important for simultaneously sustaining multiple ecosystem functions at high levels. Soil salinity is the main environmental factor that affects the plant diversity and ecosystem multifunctionality. High Soil salinity directly decreases the plant diversity, and indirectly results in the descend of ecosystem multifunctionality.

Application of entropy weight-TOPSIS method to drought resistance evaluation of common afforestation tree species in the lithoid hilly area of North China

Ze-dong LI,Zhen CAO,Ru-ming ZHANG,Yi-ran LI,Tian-tian CHENG,Yong-tao ZHANG

JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE). 2020, 55(1):  117-126.  doi:10.6040/j.issn.1671-9352.0.2019.362

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In order to explore the application of entropy weight-TOPSIS method in plant drought resistance evaluation, taking potted water control as experimental method and seedlings of 7 common afforestation tree species in lithoid hilly area of North China such as F.chinensis were used as experimental materials, then measured their net photosynthetic rate (P_n), chlorophyll content, stomatal conductance(g_s), water use efficiency (WUE), malondialdehyde (MDA) content, cell membrane permeability, superoxide dismutase (SOD) activity, proline content and relative water content of the leaves. The responses of these indicators to drought stress were analyzed, and the photosynthesis and osmotic adjustment effects of different plants under drought stress were evaluated. The results showed that, under drought stress, the C_i of photosynthetic effect and osmotic regulation effect of G.sinensis were higher than those of other tree species, which were 0.669 and 0.528, this indicates that the G.sinensis has the strongest drought resistance. Based on entropy weight-TOPSIS principle, the drought resistance of 7 tree species was evaluated by comprehensive evaluation: G.sinensis>M.azedarach>Q.acutissima>R.pseudoacacia>C.coggygria>F.chinensis>K.paniculata. The results of drought resistance evaluation of tree species based on entropy weight-TOPSIS method were consistent with the actual growth of plants and previous studies. So the comprehensive evaluation of the drought resistance of the plant is feasible by using the method.