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    Academic paper recommendation based on heterogeneous network embedding
    Kan XU,Rui-xin LIU,Hong-fei LIN,Hai-feng LIU,Jiao-jiao FENG,Jia-ping LI,Yuan LIN,Bo XU
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (11): 35-45.   DOI: 10.6040/j.issn.1671-9352.1.2019.017
    Abstract142)   HTML13)    PDF(pc) (4302KB)(384)       Save

    This paper focuses on the extraction and utilization of information from heterogeneous information network recommendation, and proposes a heterogeneous network embedding-based academic paper recommendation method. The proposed method uses the random walk strategy guided by the meta-path to generate the sequence of nodes. Then, for each meta-path, the unique embedding representation of nodes is learned by maximizing its co-occurrence probability with the adjacent nodes in the sequence obtained from the given meta-path. In addition, in order to fuse the low-dimensional representation of nodes in differentmetapaths into the final output of heterogeneous information network embedding, the different fusion functions are designed to achieve this goal, and attention mechanism is introduced to recommendation system. This paper applies the heterogeneous information network based on meta paths to solve the problem that most recommendation methods based on heterogeneous information networks rely on path similarity, which can not fully mine the potential structural characteristics of users and projects. We use DBLP data set to validate the effectiveness of the proposed model, which achieved better performance compared with the traditional model on RMSE.

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    Application impacts analysis on natural forestry management for pine plantation in central and southern mountainous area of Shandong province
    Chun-hui LING,Ming-zhong ZHANG,Gui-yun LYU,Hao-ran CUI,Pan YAP,Ye WEI,Sheng-yuan LIU,Feng-yun MA,Hua-tian WANG,Xiu-mei LIU,Ling MA
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (11): 8-17.   DOI: 10.6040/j.issn.1671-9352.0.2020.199
    Abstract74)   HTML12)    PDF(pc) (2192KB)(358)       Save

    The near-natural management experiments were carried out at three forestry stations of Culaishan, Taishan and Mingguangsi, with long-time thinning possesses of 2, 10 and 3 years, respectively. The results revealed that: (1) The effects of thinning management could promote the seedling growth compared to the controlled treatment (CK), the main height, diameter at breast height (DBH) and canopy diameter increased by 3.13%-12.89%, 3.03%-8.91% and 2.75%-25.91%, respectively. Similarly, the annual mean diameter of residual trees height, DBH and diameter of canopy also improved by 21.43%-66.67%, 9.21%-26.15% and 64.29%-300% when suffered to near-natural processing. (2) The intermediate cutting changed the canopy gap, led to a decrease in crown closure. On the contrary, it caused an increase in plant species of shrub layer especially for the light-loving plants like Platycladus orientalis and Ailanthus altissima. Consistently, it could contribute to the herbs diversity, which caused improvements of diversity indexes like Simpson, Shannon-wiener and Gleason in pure pine stand and mixed pine-oak forest compared with that in CK. At the same time, the important values of Digitaria sanguinalis, Spodiopogon sibiricus and Carex rigescens elevated. (3) The tending measurement resulted in an improvement of soil pH, and a decrease of bulk density. As well, it had a potential to accelerate the nutrient metabolism for the increasing enzyme activities of catalase, phosphatase, sucrase and urease, which increased by 6.74%-29.33%, 4.79%-4.99%, 2.13%-10.34% and 1.25%-25.56%, respectively. It could be seen that the tending operation could benefit to the stand growth, enrich the undergrowth diversity, also improve the soil quality in different stand conditions.

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    Comparative study on genetic structure of three color variants of the sea cucumber (Apostichopus japonicus) based on mitochondrial and ribosomal genes
    Zhan-sheng GUO,Zhen WANG,Xu-guang HOU,Hai-tao ZHANG
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (11): 1-7.   DOI: 10.6040/j.issn.1671-9352.0.2020.231
    Abstract85)   HTML15)    PDF(pc) (869KB)(323)       Save

    The sea cucumber Apostichopus japonicus is an important marine aquatic species in China. Selecting good breeding is a major issue for sea cucumber aquaculture, and body color is chosen as an important consideration. In order to explore the genetic structure and phylogenetic relationship of sea cucumber populations with different body color characteristics, 16S rRNA, COⅠ and 18S rRNA-ITS-28S rRNA sequences were amplified and sequenced. The results showed that the lengths of 16S rRNA, COⅠ and 18S rRNA-ITS-28S rRNA sequences were 812-830 bp, 877-915 bp and 1 536-1 572 bp, respectively. In the green, white and purple morphs of the sea cucumber, 4/5/5, 5/3/4, and 4/4/3 haplotypes were detected in 16S rRNA, COⅠ and 18S rRNA-ITS-28S rRNA sequences, respectively. The number of polymorphic loci in the COⅠ sequences was the highest, and that of 16S rRNA sequences was the smallest. The genetic distances of 16S rRNA, COⅠ and 18S rRNA-ITS-28S rRNA sequences among three color morphs were both small, ranging from 0-0.014 7, 0-0.021 2, and 0-0.010 3, respectively, and they did not reach the species differentiation level. The phylogenetic tree was constructed based on the COⅠ sequences, and Strongylocentrotus purpuratus was chose as the outgroup. The results showed that the white sea cucumbers were clustered into one branch, the purple and green sea cucumbers were cross-aggregated with each other and could not be distinguished.

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    Fault tracing method of industrial production control data network based on SDG simplified model
    Yan-hua YANG,Li-gang YAO
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (11): 46-57.   DOI: 10.6040/j.issn.1671-9352.0.2020.353
    Abstract85)   HTML9)    PDF(pc) (1763KB)(314)       Save

    For the fault diagnosis and source tracing in industrial production control data network, this paper proposes a solution based on SDG simplified model. Firstly, a SDG model is established based on the structural characteristics of the industrial production control data network, then the search space for fault location is reduced through hierarchical and demarcated modeling method.On this basis, according to the observed signal amount extracted when the business alarm occurs, analyse the survival of the nodes based on the longitudinal data and survival data. Secondly, combined with the analysis of the characteristics of network faults, the single-node fault detemination method is used to determine whether each node device is faulty. Finally, based on the fault cause classification of the fault tracing database in the traceability diagnosis rules, the root cause of the network fault is determined. Through the test and verification method, the feasibility of the proposed method in the industrial production control data network is verified, which can meet the requirements of rapid fault tracing.

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    Cut sets of outer P-fuzzy sets and extended rough sets models
    HAO Xiu-mei, LIU Ji-qin
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 1-6.   DOI: 10.6040/j.issn.1671-9352.0.2020.196
    Abstract158)      PDF(pc) (384KB)(256)       Save
    The P-fuzzy sets are a pair of inner and outer P-fuzzy sets. Inner and outer P-fuzzy sets are two different kinds of dynamic fuzzy sets. The cut sets method is frequently used in fuzzy sets discussed. The concepts of λ-cut sets, strong λ-cut sets, interval cut sets and cut sets granularity are proposed, and the cut sets and interval cut sets granularity theorems of outer P-fuzzy sets are discussed. Then, the interval cut sets decomposition theorems of outer P-fuzzy sets are given. By using the concept of the outer P-fuzzy rough membership function, four rough sets extended models are proposed such as FF) rough sets, (1F,0F) rough sets, FF)probability rough sets and FF) variable precision rough sets. The FF)rough sets theorems of the outer P-fuzzy sets are discussed. In the end, the quantitative characteristics and relationship theorem are given.
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    Strongly Gorenstein C-injective module and strongly Gorenstein C-flat module
    ZHANG Cui-ping, LIU Ya-juan
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 24-30.   DOI: 10.6040/j.issn.1671-9352.0.2020.060
    Abstract121)      PDF(pc) (385KB)(101)       Save
    Some properities of strongly Gorenstein C-injective and strongly Gorenstein C-flat modules are studied, and give the connection between the two types of modules on the specific ring.
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    A high-performance FPGA-based implementation method of SM9
    Qiu-liang XU
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 54-61.   DOI: 10.6040/j.issn.1671-9352.0.2020.322
    Abstract189)   HTML12)    PDF(pc) (10423KB)(100)       Save

    In order to improve the performance of SM9, this paper uses the fixed-base comb method for modular exponentiation in SM9, which is verified on the Xilinx's Kintex-7 FPGA platform. The experimental results show that this work can improve the performance of SM9 signature by 2.3 times, and facilitate the large-scale popularization of SM9 algorithm.

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    Influencing factors of fermentation and flocculation characteristics of Klebsiella sp. LDX1-1 polysaccharide
    Sheng-nan WANG,Xing-she LUAN,Xin-juan GUO,Min XIAO,Mei-xue DAI
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (7): 103-110.   DOI: 10.6040/j.issn.1671-9352.0.2019.667
    Abstract159)   HTML8)    PDF(pc) (2481KB)(99)       Save

    The best carbon source for the production of Klebsiella sp. LDX1-1 polysaccharide is the mixture of maltose and isomaltooligosaccharide, in which the mass fraction of isomaltooligosaccharide is 8%, and the best nitrogen source is NH4NO3 for 2g/L. 2g/L of cedar needle extract and 0.4% of Triton X-100 significantly promote the polysaccharide synthesis, and the yield increased by 12.46% and 14.38%, respectively. The optimum fermentation period is 24h, and the yield of crude polysaccharide is 23.46g/L, which is 43.14% higher than that under the basic fermentation conditions. The preliminary purified polysaccharide prepared from fermentation broth has high flocculation activity, and the flocculation rate of kaolin suspension and the Yellow River water is 98.43% and 96.31%, respectively. The qualitative analysis of the purified samples by infrared spectroscopy shows that the components of the viscous substances produced by fermentation are typical biological polysaccharides.

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    Ext-strong Ding projective modules
    GUO Hui-ying, ZHANG Cui-ping
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 31-36.   DOI: 10.6040/j.issn.1671-9352.0.2020.001
    Abstract100)      PDF(pc) (318KB)(95)       Save
    Ext-strong Ding projective modules are introduced, the class of Ext-strong Ding projective modules is projective resolving are investigated, and the Ext-strong Ding projective precover are discussed.
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    Strongly Ding projective and strongly Ding injective modules over formal triangular matrix rings
    ZHAO Yang, ZHANG Wen-hui
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 37-45.   DOI: 10.6040/j.issn.1671-9352.0.2020.032
    Abstract98)      PDF(pc) (381KB)(86)       Save
    Strongly Ding projective and strongly Ding injective modules are investigated over the formal triangular matrix ring T=(A 0U B). It is proved that if both UA and BU have finite flat dimensions, and left T-module (M1M2)φM is strong Ding projective, left A-module M1 is strong Ding projective, φM is a monomorphism, left B-module M2/Im φM is strong Ding projective.
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    Intelligent data classification and intelligent retrieval-recognition of class
    ZHANG Ling, REN Xue-fang
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 7-14.   DOI: 10.6040/j.issn.1671-9352.0.2020.178
    Abstract157)      PDF(pc) (525KB)(85)       Save
    Based on the P-set models with dynamic characteristics, and for the research of ∧ type big data, several new concepts such as αF-data equivalence class, α(-overF)-data equivalence class and F(-overF))-data equivalence class are defined, the data boundary characteristics and measurement are analyzed, and data reasoning and its structure are proposed. The main points of this paper are to define the measurement of data boundary contraction and expansion for data element redundancy and missing, analysis data reasoning to obtain the generation theorems of data equivalence class, design data intelligent retrieval algorithm and data intelligent retrieval and recognition criteria, and finally give the application.
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    Existence of positive solutions for singular boundary value problems of Hadamard fractional differential equations in abstract space
    SUN Yan-yan, LIU Yan-sheng
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 95-103.   DOI: 10.6040/j.issn.1671-9352.0.2019.833
    Abstract125)      PDF(pc) (425KB)(82)       Save
    The existence of positive solutions of singular boundary value problems in Banach space is investigated. By constructing a new cone and using the fixed point index theory of strict set compression operator, it is established that there are at least two positive solutions for the corresponding approximation of the boundary value problem. Then, using Ascoli-Arzela theorem and the relative compactness of the sequence of solutions, a sufficient condition is obtained for the existence of multiple positive solutions to boundary value problem.
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    Global structure of the set of positive solutions for a class of nonlinear third-order boundary value problems
    ZHAO Jiao
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 104-110.   DOI: 10.6040/j.issn.1671-9352.0.2020.179
    Abstract128)      PDF(pc) (349KB)(76)       Save
    This paper considers the global structure of the set of positive solutions of nonlinear third-order ordinary differential equations boundary value problems{-u(3)(t)=λf(t,u(t)), a.e. t∈[0,1],u(0)=u'(0)=0, u'(1)=αu'(η),where f:[0,1]×R→[0,∞)is a L1-Carathéodory function, 0<η<1, 1<α<1 are given constants. When f satisfies the linear growth condition, the paper obtains the global structure of the set of positive solutions of the problem by using Rabinowitz global bifurcation theorem.
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    Upper(Lower)approximation based on congruence on free semilinear spaces
    LI Xiao-chao
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 15-19.   DOI: 10.6040/j.issn.1671-9352.0.2020.121
    Abstract116)      PDF(pc) (379KB)(75)       Save
    This paper introduces the ideas of rough sets into semilinear spaces. Firstly, based on the subspace of free semilinear space, the congruence relationship is defined, and the properties of congruence classes are given. Next, the upper(lower)approximation of congruence of non empty subsets in free semilinear space is defined, and some properties of the upper(lower)approximation are studied. Lastly, the rough subspaces and quotient spaces of free semilinear spaces are studied.
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    q-Cartan matrices of self-injective Nakayama algebras
    ZHAO Tiao, ZHANG Chao
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 46-51.   DOI: 10.6040/j.issn.1671-9352.0.2020.256
    Abstract113)      PDF(pc) (433KB)(72)       Save
    The present paper mainly proves that the q-Cartan matrix of any self-injective Nakayama algebra A is diagonalizable and the determinant of q-Cartan|CA(q)|={(1-(qn)m)/(1-qn), if(n,m)=1;((1-q[m,n])(m,n))/(1-qn),if (n,m)≠1,where n is the number of simple modules, m is the length of the shortest paths in the homogeneous ideal I, and (n,m) is the greatest common divisor of n and m, [n,m] is the least common multiple of n and m.
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    Maximal subsemigroups of the finite transformation semigroup of weak Y-stabilizer
    JIN Jiu-lin, TENG Wen, ZHU Fu-yang, YOU Tai-jie, QU Yun-yun
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 55-62.   DOI: 10.6040/j.issn.1671-9352.0.2019.636
    Abstract150)      PDF(pc) (405KB)(72)       Save
    Let X be a non-empty set. Denote by T (X)the full transformation semigroup on X. Given a non-empty subset Y of X, letT(X,Y)={α∈T (X):Yα⊆Y}, and call it the transformation semigroup of weak Y-stabilizer. In this paper, we show that structure and complete classification of maximal subsemigroups of T(X,Y)whenever Y is a proper non-singleton subset of finite set X.
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    Principal congruence on Tarski algebra and modal algebra
    CAO Fa-sheng
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 20-23.   DOI: 10.6040/j.issn.1671-9352.0.2019.763
    Abstract99)      PDF(pc) (325KB)(71)       Save
    The principal congruences of Tarski algebras and modal algebras are studied. Combined with the result of principal congruence of Boolean algebra, the characterization of principal congruence of Tarski algebra and modal algebra is given.
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    Construction of retrieval dataset of procuratorate legal documents
    Jia-qi WANG,Mu-yun YANG,Tie-jun ZHAO,Zhen-yu ZHAO
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (7): 81-87.   DOI: 10.6040/j.issn.1671-9352.1.2019.048
    Abstract136)   HTML7)    PDF(pc) (940KB)(63)       Save

    Smart procuratorial is an important step in further developing procuratorial informationization. Prosecutors often deal with a large number of procuratorate legal documents. Failure to effectively organize and use the information in these instruments will reduce the efficiency of the procuratorate. Information retrieval technology can solve this problem precisely. In the legal field, the lack of Chinese retrieval datasets actually restricts the development of legal information retrieval. In this background, according to the characteristics of the procuratorate legal documents, this paper proposed a method for constructing a retrieval dataset for the procuratorate legal documents, and implements a small Chinese dataset that can be used for information retrieval research in the legal field. According to the experimental results, the performance of the dataset on different retrieval models has been verified.

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    On the facility systems reliability based on network location
    WEI Zong-tian, FANG Hui, LI Yin-kui
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 77-82.   DOI: 10.6040/j.issn.1671-9352.0.2019.914
    Abstract109)      PDF(pc) (556KB)(62)       Save
    The structure of the facility system is represented by a network, where vertices represent service facilities or customers, and the edges represent the transmission channel of goods or information. The reliability of such a facility system is to a large degree adversely affected by the edge failures in the network. In order to measure the reliability of a network in this situation, a feasible reliability concept is proposed. Based on the three classical facility location problems, set covering location problem, p-median problem and uncapacitated fixed charge location problem, a comprehensive location model is established. A heuristic algorithm is designed for solving the discrete optimal problem. It is shown by an instance that the system reliability can be improved obviously with a little cost increase.
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    Dynamic quality improvement strategies with delay effect in consumer reference quality
    De-qing MA,Jin-song HU
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 101-89.   DOI: 10.6040/j.issn.1671-9352.0.2019.190
    Abstract135)   HTML6)    PDF(pc) (1479KB)(56)       Save

    Considering the delay effect of manufacturer product improvement on consumer reference quality, the supply chain differential game models of Nash non-cooperative game, cooperative game, partial cooperative game for manufacturer to bear retailer advertising cost and partial cooperative game for retailer to bear manufacturer quality cost are constructed. The member equilibrium strategy and supply chain performance of four game modes are obtained with the help of differential game theory. It is found that the delay effect will affect the quality improvement strategy of the manufacturer, but will not affect the advertising strategy of the retailer. The marginal revenue and cost of the members are the key factors affecting the strategy and performance. The results of comparative analysis and numerical examples show that partial cooperative games of supply chain members can not realize the perfect coordination of supply chain, but it can improve the decentralized supply chain in Pareto. The strategies members performance and consumer reference quality level under cooperative games are higher with or without the delay effect.

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    Maximum matching forcing number in some special graphs
    LI Jing-jing, BIAN Hong, YU Hai-zheng
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 71-76.   DOI: 10.6040/j.issn.1671-9352.0.2019.613
    Abstract100)      PDF(pc) (550KB)(56)       Save
    The topological index of chemical molecule is a kind of numerical invariant, which can predict indirectly the physical and chemical properties of the corresponding chemical. The reformulated reciprocal degree distance index is a generalized of reciprocal degree distance, defined as:(-overR)t(G)=∑{u,v}⊆V(G)(dG(u)+dG(v))/(dG(u,v)+t), t≥0[1]. Phenylene chain is a kind of important aromatic chemical molecule, which have strongly chemical background. We determined extremal phenylene chains with minimum and maximum reformulated reciprocal degree distance indices in all phenylene chains with n hexagons.
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    Judgement of(ω)property for operators functional calculus
    JIANG Hu, CAO Xiao-hong
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 83-87.   DOI: 10.6040/j.issn.1671-9352.0.2020.083
    Abstract110)      PDF(pc) (365KB)(54)       Save
    A new spectrum set is defined basing on the semi-Fredholm perturbation theory, and by using this spectrum set, this paper characterizes the(ω)property for the bounded linear operators and their functional calculus.
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    Judgement of a-Weyls theorem for bounded linear operators
    FENG-GAO Hui-zi, CAO Xiao-hong
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 88-94.   DOI: 10.6040/j.issn.1671-9352.0.2019.729
    Abstract125)      PDF(pc) (441KB)(53)       Save
    Let H be an infinite dimensional separable complex Hilbert space and B(H) be the algebra of all bounded linear operators on H. T∈B(H) satisfies the a-Weyls theorem if σa(T)\σea(T)=πa00(T), where σa(T) and σea(T) denote the approximate point spectrum and essential approximate point spectrum respectively, and πa00(T)={λ∈iso σa(T):0<n(T-λI)<∞}. A new judgement for the a-Weyls theorem for operators and operator functions is given. Also, the spectrum mapping theorem related to spectrum is considered.
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    Detection method of hemorrhages of fundus image based on deep learning
    Wen-she YIN,Jian-feng HE
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 62-71.   DOI: 10.6040/j.issn.1671-9352.0.2019.475
    Abstract190)   HTML6)    PDF(pc) (8260KB)(49)       Save

    This paper proposes a method for detecting the bleeding point of fundus images based on convolutional neural networks (CNN) plus conditional random fields (CRF). First, in order to avoid the influence of the background area of the image on subsequent detection, refer to the gray level information in the fundus image and adjust the image to the appropriate size according to the length of the fundus center to its edge, and then linearly weight the image to enhance its brightness and contrast; then, using the cropped image block to train the CNN model for detecting the bleeding point on the CNN architecture built on the VGG network; finally, to overcome the problems of false detection and missed detection in the bleeding point detection of the CNN model, CRF is used for CNN. The probability map of the model output is post-processed to achieve accurate detection of the bleeding point of the fundus image. The detection method proposed in this paper was trained and verified on the open Kaggle and Messidor databases, and achieved 98.8% accuracy, 99.4% recall rate and 99.1% F-score. In addition, the sensitivity tested on the DIARETDB1 database reached 98.5% and the F-score was 96.1%. The experimental results show that the effectiveness and superiority of the proposed method are illustrated from both image visual and quantitative detection.

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    Low-light image enhancement algorithm based on variational structure
    Ming-xing LIN
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 72-80.   DOI: 10.6040/j.issn.1671-9352.0.2020.202
    Abstract154)   HTML8)    PDF(pc) (24083KB)(46)       Save

    Aiming at the problem that the images captured under low illumination present some defects, such as low brightness and poor visibility, a low-light image enhancement algorithm based on variational structure guided filtering is proposed. First, the maximum of R, G and B channels are searched at each pixel of the input image, and the bright channel map is obtained by using the maximum filtering. Secondly, a novel guided filtering based on variational model is constructed to refine the bright channel image to estimate the illumination component. Subsequently, the reflection component is obtained by removing the illumination component according to the Retinex model. Finally, homomorphic filtering and linear stretching are employed to further improve the contrast of the reflection component to output an enhanced image with clear visibility. Comprehensive experimental results show that this algorithm can effectively and quickly enhance the illumination and contrast of low-light images and retain details.

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    Net premium reserve in life insurance under Vasicek model with jumps
    Chun-yan SONG,Shi-long LI
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 81-88.   DOI: 10.6040/j.issn.1671-9352.0.2019.700
    Abstract153)   HTML6)    PDF(pc) (947KB)(42)       Save

    Considering the characteristics of random volatility with jumps of market interest rates, both compound Poisson process and Ornstein-Uhlenbeck process are utilized to describe the stochastic jumps and random continuous changes of interest rates respectively. A Vasicek interest model with Poisson jumps is obtained by coupling the two kinds of stochastic processes. The mathematical expressions of the cumulative interest force function and the expected discount function of money under the model are studied. At the same time, the corresponding numerical analysis is given. Based on this interest model, the calculation of the net premium reserves of life insurance products is further studied

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    A note on polynomial automorphisms
    XU Tao
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 52-54.   DOI: 10.6040/j.issn.1671-9352.0.2020.005
    Abstract97)      PDF(pc) (280KB)(36)       Save
    A polynomial automorphism of a group G is an automorphism of the formx|→(v-11xε1v1)(v-12xε2v2)…(v-1mxεmvm),where εi=±1 and v1,v2,…,vm are fixed elements in G. In this paper we prove that if G is a(nilpotent of class c)-by-(soluble of derived length d)group, then the group generated by the polynomial automorphism of G is(nilpotent of class≤c-1)-by-(soluble of derived length≤2d).
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    Multiplicity of positive solutions for fourth-order boundary value problems with nonlinear boundary conditions
    LIU Meng-xue, LI Jie-mei, YAO Yan-yan
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2021, 56 (2): 84-91.   DOI: 10.6040/j.issn.1671-9352.0.2020.486
    Abstract58)      PDF(pc) (903KB)(36)       Save
    This paper considers a class of the fourth-order boundary value problems with nonlinear boundary conditions{u(4)(t)=f(t,u(t)), t∈(0,1),u(0)=u″(0)=u(1)=0,u'(1)+C(u(1))u(1)=0,where f:[0,1]×R→[0,∞)satisfies L1-Carathéodory conditions, C:[0,∞)→[0,∞)is continuous. The existence and multiplicity of the above problems are obtained by analyzing the properties of Green function and using Leggett-Williams fixed point theorem. Finally, an example is given to verify the validity of the obtained theorem.
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    Bifurcation analysis of positive solutions for a predator-prey model with B-D functional response
    YANG Zhong-liang, GUO Gai-hui
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (7): 9-15.   DOI: 10.6040/j.issn.1671-9352.0.2020.028
    Abstract172)      PDF(pc) (414KB)(32)    PDF(mobile) (414KB)(11)    Save
    The steady-state of the predator-prey model with Beddington-DeAngelis functional response and the fear effect is studied. We first obtain the local bifurcation solutions by the bifurcation theory, then the global structure of the coexistence solutions is established. Moreover, some stability results of the bifurcation solutions are given by linear eigenvalue perturbation theory.
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    Channel decisions and coordination of closed-loop supply chain under demand and cost disruptions
    Dan-dan SUN,Ke LI,Li-bin XIE,Zong-yu MU
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (7): 88-102, 110.   DOI: 10.6040/j.issn.1671-9352.0.2019.290
    Abstract136)   HTML6)    PDF(pc) (1202KB)(31)       Save

    Considering demand and cost are disrupted by emergency events, there are three CLSC emergency models, i.e. retailer collecting, manufacturer collecting and third-party collecting. In the three decentralized collecting systems and centralized decision system, compared with equilibrium decisions in normal environment, when the disruptions of demand and cost are not large, sales quantity of products and collecting rate of used products have some robustness, but the wholesale price and selling price of products should be adjusted along the same direction with demand disruption; when the disruptions of demand and cost are large, the wholesale price, selling price, sales quantity of products and collecting rate of used products should be adjusted along the same direction with demand disruption; when the degree of demand decreasing and cost increasing are large, the three decentralized collecting systems and centralized decision system are all destroyed. In each case of demand and cost disruptions, manufacturer can obtain more profits by MRCRM system; when the degree of demand decreasing and cost increasing exceeds a certain threshold, the profits of centralized decision system decrease resulted from assuming more extra disposing costs, which results in its profits are less than MRCRM system. Furthermore, in other disruption cases, emergency revenue and expense sharing contract can solve "double marginalization" problems in MRCRM system, which improves system's operation efficiency and makes each member get Pareto improved profits.

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    Existence of solutions for singular fourth-order m-point boundary value problems
    WU Ruo-fei
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2021, 56 (2): 75-83.   DOI: 10.6040/j.issn.1671-9352.0.2020.289
    Abstract54)      PDF(pc) (364KB)(31)       Save
    This article considers the existence of positive solutions for the singular fourth-order m-point boundary value problems {u(4)(t)=f(t,u(t),u'(t)), a.e. t∈(0,1),u'(0)=0, u(1)=∑m-2i=1aiu(ξi),u(0)=0, u″(1)=∑m-2i=1aiu″(ξi)where ξi∈(0,1), i=1,2,…,m-2, 0<ξ12<…<ξm-2<1, ai∈R and ∑m-2i=1ai≠1. By using the fixed point theorem of Leray-Schauder and under some suitable assumptions of f, the existence of solutions is obtained. Note that nonlinear term f has some suitable singularities at t=1.
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    Rank and relative rank of the semigroup PD(n,r)
    ZHANG Qian-tao, LUO Yong-gui, ZHAO Ping
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (10): 63-70.   DOI: 10.6040/j.issn.1671-9352.0.2019.922
    Abstract118)      PDF(pc) (387KB)(29)       Save
    Let PDn be the semigroup of all distance-preserving partial one-to-one singular transformations on a finite-chain [n](n≥3), and let PD(n,r)={α∈PDn:|im(α)|≤r}(0≤r≤n-1)be the two-sided ideal of the semigroup PDn. By analyzing the elements with rank r of the semigroup PDn, the minimal generating set and rank of the semigroup PD(n,r)are obtained. Furthermore, the relative rank of the semigroup PD(n,r)with respect to its ideal PD(n,l)is determined for 0≤l≤r.
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    Existence of positive solutions for periodic boundary value problems of secondorder damped difference equations
    SU Xiao-xiao, ZHANG Ya-li
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2021, 56 (2): 56-63.   DOI: 10.6040/j.issn.1671-9352.0.2020.361
    Abstract77)      PDF(pc) (374KB)(27)       Save
    This paper studies the existence of positive solutions for periodic boundary value problems of second order damped difference equations{Δ2x(t-1)+p(t)Δx(t-1)+q(t)x(t)=f(t,x(t),Δx(t-1)), t∈[1,T]Z, x(0)=x(T), Δx(0)=Δx(T)with vanishing Greens function, where T > 2 is a integer, p(·),q(·) are functions, f(t,x,y):[1,T]Z×(0,∞)×R→R is continuous with respect to (x,y)∈(0,∞)×R. The proof of main results is based on nonlinear alternative of Leray-Schauder and Schauders fixed point theorem.
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    Pathological study on infection of Vibrio anguillarum and Vibrio parahemolyticus to Octopus ocellatus
    Yan-wei FENG,Zan LI,Wei-jun WANG,Guo-hua SUN,Guo-hua SUN,Xiao-hui XU
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2020, 55 (9): 102-110.   DOI: 10.6040/j.issn.1671-9352.0.2019.834
    Abstract146)   HTML7)    PDF(pc) (24826KB)(13)       Save

    In order to control aquaculture diseases and understand the influence of pathogen microorganisms on cephalopoda culture, we selected vibrio with high incidence in seawater culture, including V.anguillarum and V.parahemolyticus, to study their virulence level and pathogenic mechanism against shortarm octopus. Through direct injection of diluted bacteria solution into shortarm octopus carpus arm, the death rate and half lethal time of shortarm octopus after infection were observed, as well as the effects of various bacteria on the structures of shortarm octopus liver, gill, gill heart and white body. The results showed that V.anguillarum and V.parahemolyticus were both highly pathogenic to shortarm octopus, reaching a semi-fatality rate at 60 h and 48 h, respectively. In addition, the activity of octopus was decreased, weakness and abdominal swelling were observed; Through the observation of paraffin sections and HE staining and ultramicroscopic structure of diseased and healthy tissues, it was found that the liver, gill, gill heart and white body of the diseased octopus showed different degrees of tissue or cell structure damage. The above results indicated that both V.anguillarum and V.parahemolyticus were significantly pathogenic to shortarm octopus, and the pathogenicity of V.parahaemolyticus might be stronger, which would be one of the greatest threats of shortarm octopus large-scale farming if the conditions were suitable.

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    Matching equivalent classes of union graphs of two vertices and a path
    XIE Cheng-ling, MA Hai-cheng
    JOURNAL OF SHANDONG UNIVERSITY(NATURAL SCIENCE)    2021, 56 (1): 29-34.   DOI: 10.6040/j.issn.1671-9352.0.2020.157
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    The number of the matching equivalent graphs of 2K1 ∪ Pm is calculated, and the matching equivalent classes of 2K1∪Pm and its complement graphs can also be characterized.
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