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25 November 2017, Volume 2017 Issue 6 Previous Issue    Next Issue

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Mathematics

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On Eisenstein series generated from twisting of the geometric series SHEN Li-chien 2017, 2017 (6):  1-24.  doi: 10.3969/j.issn.1000-5641.2017.06.001 Abstract ( 615 )   HTML ( 18 )   PDF (283KB) ( 724 )   Save In this paper, we will be dealing with the twisting of geometric series by the Dirichlet characters. In conjunction with the basic tool of Fourier transform, it can be used to generate all the Eisenstein series with respect to a family arithmetic groups. References | Related Articles | Metrics

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On uniqueness of meromorphic solutions to difference Painlevé Ⅲ equations WANG Xiao-ming, GAO Zong-sheng, CHEN Min-feng 2017, 2017 (6):  25-32,60.  doi: 10.3969/j.issn.1000-5641.2017.06.002 Abstract ( 445 )   HTML ( 52 )   PDF (258KB) ( 520 )   Save We investigate the uniqueness of finite-order transcendental meromorphic solutions to difference Painlevé Ⅲ equations. We suppose w is a finite-order transcendental meromorphic solution to difference Painlevé Ⅲ equation. If w shares two distinct finite values with another meromorphic function w and they have the same poles (counting multiplicities), we conclude that w ≡ w under certain conditions. References | Related Articles | Metrics

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New Hadamard-type inequalities on fractal space and their applications SUN Wen-bing 2017, 2017 (6):  33-41.  doi: 10.3969/j.issn.1000-5641.2017.06.003 Abstract ( 430 )   HTML ( 13 )   PDF (268KB) ( 547 )   Save In the paper, using local fractional calculus theory and the theory of generalized s-convex function in the second sense on fractal sets, some new Hermite-Hadamard type inequalities involving local fractional integrals on fractal sets Rα(0 < α ≤ 1) were established. Finally, some applications of these inequalities to some error estimates for numerical integration were given. References | Related Articles | Metrics

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One scale-free network model based on two different preferential attachment probabilities MA Fei, YAO Bing 2017, 2017 (6):  42-49.  doi: 10.3969/j.issn.1000-5641.2017.06.004 Abstract ( 545 )   HTML ( 14 )   PDF (353KB) ( 591 )   Save Based on the classic scale-free network model, we set up the partial differential equation satisfied a more general network dynamic system, and then we not only find another important topological property of scale-free network, but also discuss the real background meaning of every function. Meanwhile, we extend the BA-network-model growth principle, degree-preferential attachment mechanism. Starting from a more general situation, we establish a network model containing degree-preferential attachment probability and special-graph-preferential attachment probability. By analysis, this model is scale-free. Finally, we distinguish the connect between the scope of the power law parameter γ of scale-free network and the phenomena all kinds of preferential attachment probabilities co-existing. According to the contribution level from the vertex to the whole network, we come up with a preferential attachment probability. References | Related Articles | Metrics

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Symmetry reductions, exact solutions and conservation laws of a class of forth-order partial differential equations ZHANG Li-xiang, LIU Han-ze, XIN Xiang-peng 2017, 2017 (6):  50-62.  doi: 10.3969/j.issn.1000-5641.2017.06.005 Abstract ( 709 )   HTML ( 12 )   PDF (2538KB) ( 656 )   Save The partial differential equation with constant coefficients can merely approximately reflect the law of motion of substances. Relatively the partial differential equation with variable coefficients can reflect the complex movement of substances more accurately. Therefore, it is more important to study the partial differential equations with variable coefficients. This paper investigates a class of variable coefficient partial differential equations. By using Lie symmetry analysis, the symmetries of the equations are obtained, Then the partial differential equations are reduced to ordinary differential equations. Moreover, we combine with (G'/G) expansion method and elliptic function expansion, so exact solutions to the original equation are obtained. Furthermore, the conservation laws of this kind of variable coefficient differential equations are given. References | Related Articles | Metrics

Computer Science

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An improved convexity measure for 3D meshes LI Rui, LIU Lei, SHENG Yun, ZHANG Gui-xu 2017, 2017 (6):  63-75,113.  doi: 10.3969/j.issn.1000-5641.2017.06.006 Abstract ( 400 )   HTML ( 12 )   PDF (1424KB) ( 690 )   Save In this paper we proposed an improved 3D mesh convexity measure by projecting only once a given 3D mesh onto the orthogonal 2D planes along its principal directions. Unlike the previous work which was time-consuming and required constant adaptations of the projection direction, we used the calculated result along the principal directions as an initial estimate of mesh convexity, followed by a correction process. In the initial estimation, our measure computed only once the summed area ratio of mesh silhouette images to mesh faces, along the principal directions of the mesh. Then, the mesh was sliced into a number of 2D cross sections along its principal directions. Finally, a 2D convexity measure for the 2D sliced cross sections was employed to correct the convexity overestimated by the initial estimation. Experimental results had demonstrated the effectiveness and effciency of the improved convexity measure against the existing ones. References | Related Articles | Metrics

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Cognitive heterogeneous network based on cooperative spectrum sensing and interference constraints YE Shi-tong, WAN Zhi-ping, KE Jian-bo, LIU Shao-jiang, NI Wei-chuan 2017, 2017 (6):  76-84.  doi: 10.3969/j.issn.1000-5641.2017.06.007 Abstract ( 517 )   HTML ( 15 )   PDF (590KB) ( 523 )   Save For idle channel detection accuracy and network throughput optimized on heterogeneous wireless networks, a cognitive heterogeneous network based on cooperative spectrum sensing and interference constraints is proposed. First, the proposed model of cognitive heterogeneous network system that used several center secondary user nodes to assist other nodes spectrum sensing, and the introduction of energy detection threshold improves idle channel detection accuracy of detection while saves energy. Then, the joint optimization equation of maximizing data rate was used to assignment optimal transmit power for node under constrained to limit interference power, it reduced the degree of interference and optimize network throughput. The simulation results show that, compared with the cluster-based cooperative spectrum sensing based on energy allocation strategy algorithm and QoS constraints perceived competitive power allocation algorithm, which improved network throughput, respectively, 3.4% and 1.5%, and increased the average spectral efficiency 9.3% and 7.4%, respectively. References | Related Articles | Metrics

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A comprehensive study of mapping services in China ZHANG De-tian, WANG Jia-ao, CHEN Fei 2017, 2017 (6):  85-95.  doi: 10.3969/j.issn.1000-5641.2017.06.008 Abstract ( 488 )   HTML ( 94 )   PDF (375KB) ( 1257 )   Save The mapping services have been widely used in our daily lives. People can use the services to find their nearest POI (Point of Interests), the shortest travel route from a source location to a destination location, and even life services like booking hotels, calling taxis and so on. Consequently, more and more mapping service providers have emerged in the past years in China, like Baidu Maps, Amap, Sogou Maps, Tencent Maps, Google Maps and Bing Maps. However, there is no existing study on how to select the suitable one for users/developers when they facing so many different mapping service providers. In this paper, we make thorough comparisons and experiments on mobile APPs and Web APIs of the six mapping service providers in China, and present the most three popular native mapping APIs, i.e., Baidu Maps API, Amap API and Sogou Maps API, to give readers a valuable guider for selecting their suitable mapping services. References | Related Articles | Metrics

Physics and Electronics

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Analysis of monitoring system for substation equipment based on multi -antennas RFID GUO Feng-ming, LI Bing, HE Yi-gang 2017, 2017 (6):  96-104.  doi: 10.3969/j.issn.1000-5641.2017.06.009 Abstract ( 345 )   HTML ( 13 )   PDF (1035KB) ( 588 )   Save The relative positions of electrical equipment and metallic character affect the communication performance of radio frequency identification monitoring system for substation. Considering the tunnel-like environment and metallic media in substation, a RFID(Radio Frequency Identification) tag-sensor monitoring system for electrical equipment in substation based on multi-antennas is proposed. The channel model of monitoring system is built and the performance influence factors are analyzed. The results reveal that, when the distance from the reader antennas to the tag-sensor d is less than 80m, the bit error rate of four-antennas system can be reduced one to three orders of magnitude than that of two-antennas and single-antenna systems. When 25 m < d <80 m, the bit error rate of antennas vertically placed mode is reduced from 20% to 40% than that of horizontally placed mode. References | Related Articles | Metrics

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A frequency domain electromagnetic detection transmitter in the research and design HUANG Jiang-bo, FU Zhi-hong, FU Wei 2017, 2017 (6):  105-113.  doi: 10.3969/j.issn.1000-5641.2017.06.010 Abstract ( 363 )   HTML ( 14 )   PDF (938KB) ( 527 )   Save Electromagnetic detection device is a research focus. In this paper, frequency domain electromagnetic detection transmitter topology structure, designed with up and down along the clamp, and the output current phase connection the launch of constant current source circuit, design of the clamping voltage source capacitance inductance value, constant current, system model is established. The simulation results show that the frequency domain electromagnetic detection emission function under the condition of inductive load is bigger, high firing frequency, output current amplitude, 3 times greater than that of the conventional bridge type transmission circuit. Besides, ac square wave is stable, with good linearity, etc. References | Related Articles | Metrics

Estuary and Coastal Research

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Vertical distribution patterns of suspended sediment concentration in the North Passage of the Changjiang Estuary LI Yuan, LI Zhan-hai, ZHANG Zhao, WANG Zhi-gang, YAO Hong-yi 2017, 2017 (6):  114-125.  doi: 10.3969/j.issn.1000-5641.2017.06.011 Abstract ( 480 )   HTML ( 15 )   PDF (1522KB) ( 584 )   Save Based on the vertical profile data of current velocity and suspended sediment concentration (SSC) measured in the North Passage of the Changjiang Estuary from 26th October to 9th November in 2013, the vertical distribution patterns of SSC during the neap and spring tides are studied, and the impacts of current velocity and vertical salinity gradient on the SSC profiles are analyzed. The results show that there are remarkable difference in the hydrodynamic condition between the neap tide and spring tide, with weak current velocity, low SSC, large vertical salinity gradient and strong density stratification in the neap tide, and with contrary situation in the spring tide. Affected by large salinity gradient and weak current velocity, the vertical profiles of SSCin the neap tide mainly exhibit two types, i.e., ladder type and L type. Sediment diffusion in the neap tide was strongly suppressed by the intense salinity-induced stratification, with greater SSC appeared in the lower water column and smaller SSC appeared in the upper water column. Under the influence of strong current velocity and weak stratification, the SSC profiles in the spring tide mainly display linear distribution, and suspended sediment was well mixed in the latter half of the ebb phase, with constant concentration in the whole water column. The low correlations of lnC and ln[h -z/z] reveal that the observed SSC profiles deviate from the Rouse equation significantlyin the survey period. Due to the linear distribution in the water column, most of SSC profiles in the spring tide fit the Souls by equation, and can be accurately predicted by it. References | Related Articles | Metrics

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Sea surface wind vector retrieval off the Yangtze Estuary based on Sentinel-1A QI Xian-yun, ZHOU Yun-xuan, TIAN Bo, YU Peng 2017, 2017 (6):  126-135,146.  doi: 10.3969/j.issn.1000-5641.2017.06.012 Abstract ( 398 )   HTML ( 15 )   PDF (2542KB) ( 635 )   Save This paper selected SAR images in the Yangtze Estuary from Sentinel-1A which was launched by ESA. Firstly, it extracts high-precise wind direction using multilevel wavelet transform and fourier transform. Secondly, wind speed information are obtained through three kinds of CMOD models of GMF, and compare with five sets of in-situ data and as well as wind vector from ECMWF. The results indicats that except for some sub-images containing complex texture, the precision of SAR-derived wind field is better than that of ECMWF. The multiscale wavelet transform is conducive to wind field retrieval (RMSE of wind direction are 31.6°, 29.7°, 23.5° respectively), especially the wind speed retrieval after the second level wavelet (RMSE of wind speed is 0.8 m/s). Among CMOD models, CMOD-IFR2 and CMOD4 are suitable for coastal area of the Yangtze Estuary (RMSE of wind speedis 1.08 m/s and 1.05 m/s respectively). References | Related Articles | Metrics

Geography

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Conversion study on multi-spectral information of remote sensing images GF-1 WFV, Landsat-8 OLI and Sentinel-2A MSI YANG Tian-peng, YAN Wen-jia, ZHANG Yuan 2017, 2017 (6):  136-146.  doi: 10.3969/j.issn.1000-5641.2017.06.013 Abstract ( 573 )   HTML ( 20 )   PDF (2305KB) ( 999 )   Save Owing to the restrictions in weather conditions and revisit cycle of satellites, single satellite can't successively acquire effective optical RS data for long-term monitoring the terrestrial environments. Therefore, it is crucial important to analyze the multi-spectral information of multi-source RS data. In this study, two groups of clear RS images (GF-1 and Landsat-8, GF-1 and Sentinel-2A), in along with ground survey data, were respectively acquired on identical date. Four bands, blue, green, red and near infrared (NIR), were selected to compare their spectral characteristics. At the same time, conversion equation for reflectance of four corresponding spectral bands was derived respectively via statistical regression method. The result shows that each pair of bands in the two comparing groups has a strong correlation. And, these conversion equations can effectively converse spectral information in between each band of two comparing groups with a better precision. This study provides a useful technological approach for the identical date information integration and syngeneic application of multi-spectral RS data from the same day, as well as quantitatively monitoring the long-term dynamics in environments and resources at regional scale. References | Related Articles | Metrics

Ecological and Environmental Science

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Analysis and assessment on monthly dynamics of water quality at Taopu industrial zone in Shanghai ZHANG Ting-hui, HUANG Min-sheng, MA Ming-hai, ZHANG Wen, CUI He 2017, 2017 (6):  147-155.  doi: 10.3969/j.issn.1000-5641.2017.06.014 Abstract ( 496 )   HTML ( 13 )   PDF (1029KB) ( 465 )   Save Taking pH, WT, DO, SD, BOD5, CODCr, CODMn, TOC, NH3-N, NO3-N, TN, Chl-a, DP and TP as the primary parameters, four medium or small creeks in Shanghai Taopu industry area are chosen as research rivers to evaluate the water quality, analyze temporal variation of water quality and identify pollution sources, by using analysis method such as principal component analysis, comprehensive pollution index, comprehensive nutritive index, organic pollution index and comprehensive water quality identification index. The research results indicate that Gongye River was the most polluted river in the four rivers, followed by Xiaozhai River and Zhangjin River, and Hongqi River was the best. TN and TP were the primary pollution parameters. DP was the main composition of TP, and NH3-N is the main composition of TN. In industry area, pollution control of small malodorous rivers should focus on source control, and take the integrative measurements like "source control and retention". References | Related Articles | Metrics

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Analysis on relationship between mosquito larvae breeding and river water environment in Shanghai MA Ming-hai, LIU Shan-wen, HUANG Min-sheng, LENG Pei-en 2017, 2017 (6):  156-163.  doi: 10.3969/j.issn.1000-5641.2017.06.015 Abstract ( 426 )   HTML ( 13 )   PDF (655KB) ( 532 )   Save Monthly data on water quality and larval density were obtained from 7 rivers in Shanghai from July 2012 to July 2013, in order to determine the effects of river water environment on the distribution and abundance of immature mosquitoes. Fuzzy clustering method was used for evaluation of river water quality. Correlation analysis of larval density and water quality was implemented. Results showed that 3 rivers were considered as positive rivers from total 7 rivers. Culex pipiens pallens was the predominant species in the studied regions. High incidence of larvae from urban rivers appeared in late spring-early summer and larval density reached a peak in May. Larval density was positively significant with dissolved phosphate (DP) (p <0.01). Moreover, larval density increased significantly with the increase of Chla concentration (p <0.05) when the concentration of chlorophylla (Chla) was lower than 80 mg/m3. Slow-flowing river might be a potential habitat for some mosquito species under the appropriate conditions of water environment. References | Related Articles | Metrics