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25 November 2020, Volume 2020 Issue 6 Previous Issue    Next Issue

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Mathematics

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The Fourier transform of trigonometric functions on the multiplicative group ${\mathbb Z}^{\times}(m)$ Lichien SHEN 2020, 2020 (6):  1-15.  doi: 10.3969/j.issn.1000-5641.201911023 Abstract ( 451 )   HTML ( 746 )   PDF (602KB) ( 171 )   Save Based on the Fourier transform on the multiplicative group $ {\mathbb Z}^{\times}(m)$, we study a class of trigonometric sums and reveal interesting connections between these sums and number theoretic quantities, such as Gauss sums, the class number of imaginary quadratic fields, and the Bernoulli number. References | Related Articles | Metrics

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Robust dissipative control for discrete-time periodic Markovian jump systems LI Xiuying, JIANG Nan 2020, 2020 (6):  16-23.  doi: 10.3969/j.issn.1000-5641.201911036 Abstract ( 319 )   HTML ( 637 )   PDF (526KB) ( 79 )   Save In this paper, we discuss the robust dissipative control problem of uncertain discrete-time periodic Markovian jump systems with incomplete transition rates. By employing the Lyapunov function, a periodic state feedback controller using linear matrix inequalities is designed, that ensures the resultant closed-loop system with incomplete transition rates is stochastically stable and strictly dissipative. Lastly, an example is given to illustrate the effectiveness of the proposed method. References | Related Articles | Metrics

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Vertex-distinguishing E-total coloring of a complete bipartite graph K9, n (93 ≤ n ≤ 216) CHEN Xiang’en, YANG Weiguang 2020, 2020 (6):  24-29.  doi: 10.3969/j.issn.1000-5641.201911028 Abstract ( 393 )   HTML ( 611 )   PDF (784KB) ( 128 )   Save Let $G$ be a simple graph. A total coloring $f$ of $G$ is called an E-total coloring if no two adjacent vertices of $G$ receive the same color, and no edge of $G$ receives the same color as one of its endpoints. For an E-total coloring $f$ of a graph $G$, if $C(u)\neq C(v)$ for any two distinct vertices $u$ and $v$ of $V(G)$, where $C(x)$ denotes the set of colors of vertex $x$ and of the edges incident with $x$ under $f$, then $f$ is called a vertex-distinguishing E-total coloring of $G$. Let $\chi _{vt}^{e}(G)=\min\{k: G$ has a $k$-VDET coloring$\}.$ Then, $\chi _{vt}^{e}(G)$ is called the VDET chromatic number of $G$. By using contradiction, the method of a combinatorial analysis and the method of constructing specific coloring, the VDET coloring of a complete bipartite graph $K_{9, n}$ is discussed and the VDET chromatic number of $K_{9, n}\; (93\leqslant n\leqslant 216)$ is determined. References | Related Articles | Metrics

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Datko-Pazy theorem for nonuniform exponential expansiveness of linear skew-product semiflows YUE Tian, SONG Xiaoqiu 2020, 2020 (6):  30-37.  doi: 10.3969/j.issn.1000-5641.201911042 Abstract ( 458 )   HTML ( 105 )   PDF (556KB) ( 170 )   Save In this paper, the nonuniform exponential expansiveness of linear skew-product semiflows is studied in Banach spaces based on Lyapunov norms. Some continuous and discrete versions of necessary and sufficient conditions for nonuniform exponential expansiveness are obtained via Datko-Pazy methods. The obtained conclusions are generalizations of well-known results in exponential stability and exponential dichotomy theory (Datko, Pazy, Preda et al.). Herein, we apply the main results to the study of nonuniform exponential dichotomy of linear skew-product semiflows. References | Related Articles | Metrics

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Existence and multiplicity of positive solutions for fourth-order boundary value problems with a fully nonlinear term YAO Yanyan, LI Jiemei 2020, 2020 (6):  38-45.  doi: 10.3969/j.issn.1000-5641.201911026 Abstract ( 387 )   HTML ( 360 )   PDF (546KB) ( 151 )   Save In this paper, we discuss the fourth-order two-point boundary value problem $\left\{ {\begin{array}{*{20}{l}} {{u^{(4)}}(t) = f(t,u(t),u'(t),u''(t),u'''(t)),t \in (0,1), }\\ {u(0) = u'(0) = u''(1) = u'''(1){\rm{ = 0}}. } \end{array}} \right.$ Here, the nonlinear term $f$ contains $u'$, $u''$ and $u'''$; therefore, the problem is a fourth-order boundary value problem with a fully nonlinear term. By using the two fixed point theorems of Leggett-Williams type, the existence of at least two or at least three positive solutions are obtained under the term $f$ that satisfies certain conditions. Finally, two examples are given to verify the theorems. References | Related Articles | Metrics

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An algebroidal function of infinite order with given T directions ZHANG Jin 2020, 2020 (6):  46-51.  doi: 10.3969/j.issn.1000-5641.201911021 Abstract ( 354 )   HTML ( 254 )   PDF (589KB) ( 110 )   Save This paper explores the existence of infinite order meromorphic functions and algebroidal functions with given T directions. An algebroidal function $ \omega(z) $ of infinite order was constructed such that for an arbitrary given non-empty closed set of real numbers $ E\pmod {2\pi} $, $\{z: \arg z = \theta, \theta\in E\}$ is the set of all T directions and Borel directions of infinite order of $ \omega(z) $; using a method of cyclic values-assigned, the distribution of singular directions for meromorphic functions and algebroidal functions of infinite order is obtained. References | Related Articles | Metrics

Computer Science

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CedarAdvisor: A load-adaptive automatic indexing recommendation tool YANG Wencan, HU Huiqi, DUAN Huichao, HU Yaoyi, QIAN Weining 2020, 2020 (6):  52-62.  doi: 10.3969/j.issn.1000-5641.201921013 Abstract ( 450 )   HTML ( 364 )   PDF (691KB) ( 266 )   Save Indexes play a pivotal role in improving the performance of queries. One of the important tasks of database administrators is to select appropriate indexes for databases. However, with the increasing complexity of database workloads, the rising amount of data volumes, and the gradually increasing number of tables, it has become more and more difficult to artificially analyze workload cost, select appropriate indexes, and estimate database spatial changes. This paper designs a load-oriented automatic indexing recommendation tool: CedarAdvisor. It collects workload automatically from logs and counts query frequency. First, it generates a candidate index for each query and then evaluates the respective revenue and cost of these candidates. Finally, it generates an indexing recommendation for the complete workload through a dynamic programming algorithm. We verify the effectiveness of the tool through experiments on the distributed database. References | Related Articles | Metrics

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Online map matching algorithm based on the gated recurrent unit model CHEN Liangjian, XU Jianqiu 2020, 2020 (6):  63-71.  doi: 10.3969/j.issn.1000-5641.201921022 Abstract ( 480 )   HTML ( 366 )   PDF (808KB) ( 215 )   Save Map matching is a key technology in the field of road network trajectory data analysis. A fast and accurate map matching algorithm can provide good technical support for upper-layer applications. With the explosive growth of trajectory data, existing online map matching algorithms experience a delay phenomenon; in particular, in the context of low-frequency trajectory data, it is impossible to quickly perform map matching on trajectory data. The development of neural networks and deep learning provide new methods for solving these problems. This paper uses the gated recurrent unit(GRU) model to quickly locate candidate segments of trajectory sampling points, thus accelerating the calculation process for online map matching. The proposed method is experimentally compared to the latest online map matching algorithm; the results show that the GRU-based online map matching algorithm can effectively speed-up the matching process and improve matching efficiency. References | Related Articles | Metrics

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A certificate management system for the completion of online education based on blockchain technology HUANG Libo, WANG Wei, XU Yanjun, CHEN Xugang 2020, 2020 (6):  72-81.  doi: 10.3969/j.issn.1000-5641.201921019 Abstract ( 584 )   HTML ( 571 )   PDF (949KB) ( 173 )   Save In the current educational environment, online education lacks credible proof of completion. After learning courses on the online education platform, the students cannot get a credible certificate of completion; the completion certificate given by a few educational platforms cannot be recognized by the society because of its centralized storage, which limits the development of online education. In order to solve these problems, the blockchain-based online education completion certificate management system is designed and implemented by using the characteristics of decentralization and non-tampering of the blockchain. The electronic certificate of completion is in the form of digital assets, and the student’s learning record is kept in the certificate of completion, which guarantees the authenticity and reliability of the certificate. On this basis, based on the Hyperledger Fabric, smart contracts such as certificate generation and distribution are realized to ensure that they do not need to be operated by third parties. At the same time, multiple query interfaces are provided by the system, such as the historical trace of the certificate, which improve the efficiency of verification of online education platform learning outcomes; in addition, online education courses are recorded in blockchain in the form of publisher’s assets, which enhances copyright protection in online education. References | Related Articles | Metrics

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A method for community contribution incentives based on ethereum XIAO Dalong, ZHANG Jingwei, YANG Qing, ZHOU Ya 2020, 2020 (6):  82-89.  doi: 10.3969/j.issn.1000-5641.201921014 Abstract ( 470 )   HTML ( 657 )   PDF (804KB) ( 158 )   Save Monetization of community contributions is a way to promote community development. The existing solution, implemented on the Internet, requires that the platform’s manager controls the distribution and use of community tokens (i.e., currency issued by private or institutional entities), which hinders community development. In this paper, we propose a method to motivate community members to make contributions. The proposed method primarily relates to token allocation, voting, trading, and community arbitration based on tokens and votes. It transforms the contribution of the community into cryptocurrency, and the tokens’ owners are positively correlated with the contributions they make; this concept effectively reflects contribution to the community. The voting results reflect the will of the community. The deposit model defines supply requirements for the tokens. Finally, we use statistics on the use of gas with smart contracts. The results show that the average cost of gas is currently around 70 000, and the cost of gas with the proposed method is less. References | Related Articles | Metrics

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Study of an improved hybrid particle swarm optimization algorithm for solving 0-1 knapsack problems YAO Ruoxia, XUE Dan, XIE Juanying, FAN Hong 2020, 2020 (6):  90-98.  doi: 10.3969/j.issn.1000-5641.201921025 Abstract ( 587 )   HTML ( 650 )   PDF (1031KB) ( 356 )   Save In order to solve 0-1 knapsack problems with greater stability and efficiency, we propose a BPSOSA-CGOO (Hybrid optimization algorithm based on the BPSO (binary particle swarm optimization), the simulated annealing (SA) algorithm and the combined greedy optimization operator (CGOO)) algorithm which is composed of the BPSO, the greedy optimization strategy, and the simulated annealing algorithm. Simulation experiments of 9 groups of different dimensions show that the BPSOSA-CGOO algorithm can solve 0-1 knapsack problems efficiently for small population sizes and iteration times. Meanwhile, it was observed that experiments performed with the algorithm can also find a better solution for 20-dimensional test data. In independent and repeated experiments, the BPSOSA-CGOO algorithm can achieve the optimal solution with high probability for both low-dimensional and high-dimensional knapsack problems; hence, stability and reliability is significantly improved when using the BPSOSA-CGOO algorithm to solve high-dimensional knapsack problems. References | Related Articles | Metrics

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The adoption process for disruptive innovation: A theoretical analysis WANG Ye, QU Linchi 2020, 2020 (6):  99-104.  doi: 10.3969/j.issn.1000-5641.202021002 Abstract ( 480 )   HTML ( 596 )   PDF (477KB) ( 286 )   Save Looking back on history, we observe that many industries generate disruptive innovations intermittently. It is worth noting that those who adopt new technologies for commercialization are usually not the incumbent leading companies with the strongest technical and financial strength, but rather companies that are established later in time, who operate on a smaller scale and with less technical strength. This article explains this phenomenon based on a two-stage game model. The advantages of incumbent companies in traditional technologies often become obstacles in their switch to innovative technologies. Companies established later in time can leverage the late-comer advantage to strategically reduce profits of new technology products, thereby blocking incumbent enterprises from the new product market. References | Related Articles | Metrics

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Defect detection on aluminum surfaces based on deep learning ZHANG Xu, HUANG Dingjiang 2020, 2020 (6):  105-114.  doi: 10.3969/j.issn.1000-5641.201921021 Abstract ( 1352 )   HTML ( 602 )   PDF (1521KB) ( 851 )   Save With the application of information technology to industrial manufacturing, big data research in industrial manufacturing has become an important basis for realizing intelligent manufacturing and helping the government to guide the transformation and upgrade of manufacturing enterprises. In traditional metal manufacturing industries, like steel and aluminum, there are challenges, such as uncalibrated and rudimentary production techniques. Therefore, it is urgent to improve production processes and production efficiency by using newer generation information technology, such as artificial intelligence. The surface of aluminum, for example, must be inspected during the manufacturing process. Existing surface defect detection techniques for aluminum materials is limited to traditional manual naked eye inspection-which is very laborious-or traditional machine vision algorithms-which have a low rate of detection. Hence, surface defects cannot be accurately judged in a timely fashion. This paper studies the use of deep learning for surface defect detection of aluminum materials. Firstly, two major target detection algorithms, Faster R-CNN and YOLOv3, are used to detect the defects on a set of aluminum materials. Then, based on the YOLOv3 algorithm, the detection ability of small defects on aluminum surfaces was improved. We conducted experiments on the “Aluminum Profile Defect Recognition” dataset provided by the Guangdong Industrial Intelligent Manufacturing Big Data Innovation Competition. The experimental results showed that the mean average precision (mAP) of the improved algorithm is 3.4% higher than that of YOLOv 3 and 1.8% higher than that of Faster R-CNN. References | Related Articles | Metrics

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Online portfolio selection based on quadratic smooth-gray prediction LIU Xiaoyu, HUANG Dingjiang 2020, 2020 (6):  115-128.  doi: 10.3969/j.issn.1000-5641.201921020 Abstract ( 447 )   HTML ( 490 )   PDF (784KB) ( 209 )   Save In recent years, online portfolios have been a popular topic of research in computational finance. The existing strategies used to forecast stock prices is not ideal, and accurate prediction of stock prices is important for evaluating investment portfolios. Considering the lag in stock prices and the complexity of their distribution, this paper makes use of second-order information in stock prices, for the first time, and proposes four strategies, namely DMAR(DMA(double moving average) reversion), DEAR(DEA(double exponential average) reversion), GMR(GM reversion), and DA-GMR(DA-GM reversion). The second-order moving average method, the second exponential sliding prediction method, and the gray prediction method are used to predict price data for the next period; integrated learning optimizes the results of second-order smoothing prediction and the gray prediction is used to obtain the predicted price. Next, we use PA(passive-aggressive) algorithms to update the portfolio, and we arrive at four portfolio strategies. We verify the effectiveness of these strategies using real data from the financial market. The results show that compared with existing algorithms, the four strategies proposed in this paper achieved higher cumulative returns on datasets for NYSE(O), NYSE(N), DJIA, and MSCI. References | Related Articles | Metrics

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Research on a Tang Poetry automatic generation system based on an evolutionary algorithm MU Zhaonan, LIU Mengzhu, SUN Jieping, WANG Cheng 2020, 2020 (6):  129-139.  doi: 10.3969/j.issn.1000-5641.201921017 Abstract ( 443 )   HTML ( 489 )   PDF (699KB) ( 224 )   Save In this paper, research on an automatic generation algorithm for Tang poetry, one of the poetry genres, is carried out. The research work consists of the GloVe(Global Vectors for Word Representation) model to train-word vectors, an initial population scheme based on keywords and peaceful rhymes, a fitness function for grammatical and semantic weights, and a selection strategy used in tournament algorithms; the latter includes heuristic crossover and heuristic mutation operators as well as automatic generation of Tang poetry based on an evolutionary algorithm. Experiments show that by providing keywords the established model and system can achieve the initial goal for automatic generation of Tang poems. After manual modification, the proposed system can generate valuable and appreciable Tang poems. References | Related Articles | Metrics

Life Sciences

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New records of Oedichirus astoni and Procirrus lewisii (Coleoptera: Staphylinidae: Paederinae) XU Wang, LIANG Hong, TANG Li, ZENG Qinghuai, QIAO Yujia 2020, 2020 (6):  140-143.  doi: 10.3969/j.issn.1000-5641.201932007 Abstract ( 492 )   HTML ( 428 )   PDF (484KB) ( 207 )   Save In a survey of rove beetles in Qiniangshan Nature Reserve of Guangdong Province, we found two new species: Oedichirus astoni Rougemont, 2017 and Procirrus lewisii Sharp, 1889. The diagnostic characteristics of these two species are described and illustrated in this paper. References | Related Articles | Metrics

Ecological and Environmental Sciences

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Spatial and temporal distribution of petroleum pollution and influence factors in the Taipu River LI Gen, XIE Yihan, WANG Huaxiang, YANG Kai 2020, 2020 (6):  144-153.  doi: 10.3969/j.issn.1000-5641.201931010 Abstract ( 410 )   HTML ( 289 )   PDF (1397KB) ( 171 )   Save The spatial and temporal distribution of petroleum pollution in the Taipu River was analyzed using a clustering methodology. The stationary source and mobile source of petroleum pollution were surveyed and monitored to determine their influence on the Taipu River. The results showed that the average over-limit rate of petroleum pollution was 62.96% among the 9 monitoring stations in the Taipu River. Luxu bridge (S4) and Jinze hydrometric station (S5) in the middle and lower Taipu River, respectively, were the primary stations with petroleum pollution. The peak level of petroleum pollution was observed during the dry period of the Taipu River. Petrol stations and wharves in the estuary of Fenhu Lake were the primary stationary source of petroleum pollution in the trunk stream of Taipu River. The mobile source of petroleum pollution from boats was primarily concentrated on the middle and lower Taipu River, and the number of transit boats had a significant positive correlation with the concentration of petroleum pollution. Based on the spatial and temporal distribution of petroleum pollution in the Taipu River, this article proposes guidelines for petroleum pollution prevention and policy implications. References | Related Articles | Metrics

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A study on temporal and spatial distribution characteristics of dissolved oxygen in surface water of megacities WANG Huaxiang, CHU Xiaoye, CHEN Ying, XU Lu, YANG Kai 2020, 2020 (6):  154-163.  doi: 10.3969/j.issn.1000-5641.201931011 Abstract ( 482 )   HTML ( 316 )   PDF (1177KB) ( 230 )   Save The dissolved oxygen (DO) zoning method was used to analyze the temporal and spatial characteristics of 259 river monitoring sites in Shanghai in 2016. The results showed that: ① Time periods with the highest mean DO can be ranked according to the following sequence: winter > spring > autumn > summer, non-flood period > flood period. ② DO had significant spatial stratification. Low-oxygen areas (DO < 2 mg/L) were mainly distributed in highly urbanized geographies, such as the city center and nearby suburban areas, changing with both season and flood period and seemingly affected by surface runoff and the discharge of pumping stations. High-oxygen areas (DO > 6 mg/L) were distributed in areas with high water ecological environmental requirements and occasionally appeared in the suburbs. Most of the annual changes in DO belonged to the median areas (DO: 4 ~ 6 mg/L), and were affected by both industry and agriculture. ③ Correlation anlysis of water quality factors indicated that DO was significantly correlated with water temperature (–0.434), pH(0.332), CODMn(–0.219), CODCr(–0.234), BOD5(–0.197), NH3-N(–0.299), TP(–0.370), TN(–0.191), Vol-P(–0.159), petroleum(–0.207). Stepwise regression analysis showed that DO was significantly affected by T, pH, NH3-N, TP and petroleum; the analysis showed, furthermore, that DO restricted factors varied in different seasons. References | Related Articles | Metrics

Educational Informationization

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Remote interview identity authentication based on audio comparison LIN Xiaoqin, MAO Min, GONG Lingling, JI Li 2020, 2020 (6):  164-171.  doi: 10.3969/j.issn.1000-5641.201942001 Abstract ( 414 )   HTML ( 528 )   PDF (864KB) ( 149 )   Save There are vulnerabilities in conducting remote interviews via simple real-time communication software. To this end, this paper proposes a simple and easy remote identity authentication scheme, whereby the recruitee only needs to use general communication software. There is no need to install special software or special hardware systems, which is particularly convenient for recruitees residing in remote areas or international locations. Recruiters need to install audio capture and screen capture software on their computer; once the recruitee is admitted into the interview, the recruiter can achieve identity authentication using audio and video comparison technology. In order to verify the feasibility of this scheme, we carried out two rounds of experiments, collecting remote voice data from seven different countries through a series of software analysis tools as well as manual comparison. The experimental results show that the scheme has a high degree of accuracy for identity authentication, laying the foundation for prospective fully automatic authentication. References | Related Articles | Metrics