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    Multiple bacteria species were involved in hepatopancreas necrosis syndrome (HPNS) of Litopenaeus vannamei
    HUANG Zhijian;CHEN Yonggui;WENG Shaoping;LU Xiaofeng;ZHONG Lihong;FAN Wenzhou;CHEN Xuling ;ZHANG Huiwen;HE Jianguo
       2016, 55 (1): 1-11.   doi:10.13471/j.cnki.acta.snus.2016.01.001
    Abstract564)      PDF (5835KB)(3500)      

    In recent years, a disease outbreak occurred in >50 percent of Litopenaeus vannamei farms at about 30 days after frys are released into the ponds in southern China. About 80% culture shrimps were dead in culture period. The clinical symptoms of the diseased shrimps include atrophy and necrosis of the hepatopancreas, weakened activity, and shrimp found dead in the bottom of the pond. The farmers in China usually called this symptom as “hidden death disease”. Since hepatopancreas atrophy and necrosis are the main symptoms of the disease, so we called this disease as hepatopancreas necrosis syndrome (HPNS). In March 2012 to October 2013, we have collected the diseased L. vannamei with the symptoms of HPNS in 12 farms from Guangdong, Hainan and Guangxi provinces, China. Histopathology showed necrosis of hepatopancreas of the diseased shrimps, disappearance of some hepatopancreatic epidermal cells, and connective tissue. We used PCR to detect the presence of 11 viruses in 305 HPNS shrimps and performed artificial viral infection to healthy shrimps. The artificially infected shrimps did not show symptoms of HPNS. A total of 383 bacteria strains were identified from hepatopancreas, hemolymph and intestine of 63 diseased shrimps. These bacteria belong to 10 genera, 49 species. We isolated Vibrio parahaemolyticus from 38 shrimps, Bacillus cereus from 34 shrimps, B. thuringiensis from 20 shrimps and V. cholera from 19 shrimps. Injection and immersion of V. parahaemolyticus and B. thuringiensis can cause symptoms of HPNS. The results suggest that multiple bacteria were involved in HPNS of L. vannamei.

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    Robust Adaptive Boundary Control of a Flexible Manipulator with Unknown Boundary Disturbance
    WENG Xuan;YANG Longgang;LIU Yu;ZHAO Zhijia;WU Yilin
       2015, 54 (3): 44-50.  
    Abstract315)      PDF (1975KB)(1689)      
    To suppress the vibration and improve the vibration control for a flexible manipulator with the system parametric uncertainty and unknown boundary disturbance uncertainty, a robust adaptive boundary control with boundary disturbance observer is proposed by using adaptive control and boundary control technologies based on the manipulator's parameter estimation to suppress the vibration of the manipulator. With the proposed control scheme, system parameter uncertainty can be compensated and the control spillover problem can be avoided, and the boundary disturbance observer can attenuate and track the unknown boundary disturbance. The stability and uniform boundedness of the control system are both proved by Lyapunov's synthesis method. Simulation results demonstrate the effectiveness of the proposed control method to suppress the manipulator's vibration.
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    A New Fixed Point Theorem of Quasi-Contractions on Cone Metric Space
    XU Shaoyuan;MA Chao;ZHOU Zuoling
       2015, 54 (5): 1-4.  
    Abstract218)      PDF (740KB)(1374)      

    By replacing Banach spaces by Banach algebras as the underlying spaces of cone metric spaces, the concept of cone metric spaces with Banach algebras has been introduced. And a fixed point theorem of quasi-contractions with the assumption of normality has been proved. By omitting the assumption of normality and utilizing the theory of c-sequence, the existence and uniqueness of the fixed point for the quasi-contractions is obtained in the setting of cone metric spaces with Banach algebras. As a consequence, the corresponding result in the literature is improved and generalized.

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    WASD neural network activated by bipolar sigmoid functions together with subsequent iterations
    ZHANG Yunong;XIAO Zhengli;DING Sitong;MAO Mingzhi;LIU Jinrong
       2016, 55 (4): 1-10.  
    Abstract239)      PDF (3067KB)(810)      

    A weights-and-structure-determination (WASD) algorithm is proposed for the neural network using bipolar sigmoid activation functions together with subsequent iterations, which is the combination of the Levenberg-Marquardt algorithm and the weights-direct-determination method for neural network training. The proposed algorithm, combined with the Neural Network Toolbox of MATLAB software, aims at remedying the common weaknesses of traditional artificial neural networks, such as long-time learning expenditure, difficulty in determining the network structure, and to-be-improved performance of learning and generalization. Meanwhile, the WASD algorithm has good flexibility and operability. Taking data fitting of nonlinear functions for example, numerical experiments and comparison results illustrate the superiority of the WASD algorithm for determining the optimal number and optimal weights of hidden neurons. And the resultant neural network has more excellent performance on learning and generalization.

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    Spectrum Sensing and Throughput Tradeoff for Cognitive MIMO System
    LUO Liping;;LI Xueyi;QIN Jiayin
       2012, 51 (2): 6-11.  
    Abstract1388)      PDF (4129KB)(799)      

    Spectrum sensing-throughput tradeoff is investigated for a cognitive MIMO system. The objective is to find the optimal spectrum sensing time and optimal power allocation to maximize the throughput of secondary user. Simulation results show that there is indeed a unique optimal sensing time to make the throughput achieve the maximum. Further, the throughput of SU can be improved by using optimal power allocation. The throughput of SU with different spectrum sensing algorithms including energy detection and eigenvalue-based detection is compared by simulations. The results show that the eigenvaluebased detection is very appropriate for cognitive MIMO system, which is not only more robust than energy detection, but also satisfies the requirement of throughput.

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    Cited: Baidu(1)
    Propagation of the Quasi-Biweekly Oscillations Related to Rainfall Abnormity in the First Rainy Season over Southern China
    CHEN Si;JIAN Maoqiu
       2015, 54 (3): 130-137.  
    Abstract176)      PDF (24999KB)(715)      
    The relationship between the quasi-biweekly oscillation(QBW: here defined as a 10~25 day oscillation) abnormity of May-June rainfall over southern China and the QBW propagation from the tropics and mid-latitudes is studied based on the composite analysis. The results indicate distinct QBW propagations in different May-June rainfall abnormal cases. The strong QBW rainfall abnormal cases in May in southern China are linked to the QBW propagations not only from the Bay of Bengal but also from the mid-latitudes of northwestern China. However, the weak QBW rainfall abnormal cases in May are just linked to the QBW propagations from the tropics. In June, the strong and weak QBW rainfall abnormal cases in southern China are influenced by the QBW propagations from the Bay of Bengal and from the mid-latitudes,respectively.
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    A Review of Evaluation of External Costs in Road Transport
    CAI Ming;ZHOU Zhanhong
       2015, 54 (4): 1-7.  
    Abstract210)      PDF (1272KB)(644)      

    External costs in road transport are important indicators that evaluate the impacts on bystanders brought by road transport activities. They play significant roles in assessing comprehensive value of road transport infrastructures and policies. By reviewing the advanced literature of evaluation of external costs in road transport, the evaluation methods of external congestion cost, external accident cost, air pollution cost, noise cost and global warming cost in road transport are summarized systematically. Then, the advantages, disadvantages and applicability of different evaluation methods of each external cost are analyzed in detail. At last, the emphases and difficulties of conducting evaluation of exteranl costs in road transport are discussed and some suggestions about carring out evaluation study of external costs in road transport in Chinese urban area are offered. In these suggestions, the actuality of evaluation research of external costs in road transport in China is taken into account.

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    Anthraquinones and nitrogen secondary metabolites from the coral-derived symbiotic fungi NG-15-3 of South China Sea
    LI Xiuting;LIU Bingxin;HU Guping;WANG Yumei;ZHANG Cuixian
       2016, 55 (1): 96-101.   doi:10.13471/j.cnki.acta.snus.2016.01.017
    Abstract240)      PDF (997KB)(641)      

    In order to study the secondary metabolites from the coralderived symbiotic fungi NG15-3 of South China Sea, the compounds were isolated by silica gel column chromatography and HPLC. Their structures were identified on the basis of spectral data and physical constant comparison. Four anthraquinones and six nitrogen compounds were isolated as preechinulin (1),emodin (2),1-O-methyl emodin(3),physcion (4),carviolin (5),cyclo-(Phe-Gly) (6),cyclo-(Gly-Pro) (7),3H-imidazole-4-carboxylic acid (8),2-methyl-3H-imidazole-4-carboxylic acid (9) and 1H-pyrrole-2-carboxylic acid (10). All the secondary metabolites were firstly acquired from the coralderived symbiotic fungi NG-15-3 of South China Sea and compound 1 was a precursors of the monodehydro-2,5diketopiperazines,which showed varied biological activity.

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    Design Synthesis and Application of Anti-tumor Compound 6-Bromo-Indole-3-Carbinol
    TAO Bingzhi;CHEN Heru;
       2012, 51 (2): 63-65.  
    Abstract1352)      PDF (657KB)(640)      
    Applying o-nitrotoluent as starting material, 6-bromo-indole-3-carbinol was synthesized via multiple-step reactions including bromidation, aldollike condensation, cyclization, Vilsmeier-Haack formylation and reduction. The overall yield reaches 26.5%. The structures of all the products have been confirmed by ESI-MS and NMR. Based on the scaffold of the title compound, series of 6-substituted indole-3-carbinols can be prepared in search for the better drug-like compounds.
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    The Research and Design of Data Center Based on the Public Safety Emergency Platform
    GU Yan
       2012, 51 (2): 17-21.  
    Abstract1071)      PDF (2120KB)(639)      
    Data, plan, model, knowledge and decisionmaking method for the storage and use as the core of public security data center is composed of storage devices, network equipment, application data and application integration.The data center has storage, query, management and maintenance functions. According to the demand of emergency platform, data center uses “ level + mixed ” method for architecture design. In the core layer, data, preplan, model, knowledge and decision-making method are mixed together according to the structure.The design of data center structure can realize data integration and management and provide effective access for a variety of application of emergency platform.
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    Tri-variable Polynomial Smoothing Spline with Natural Boundary Conditions for Scattered Data
    XU Yingxiang;;GUAN Lutai;XU Weizhi
       2012, 51 (2): 22-29.  
    Abstract1199)      PDF (2210KB)(628)      
    A spline smoothing method with natural boundary conditions for scattered data of 4D are considered. In order to minimization the given objective functional, using the spline function methods of Hilbert space, the solution is constructed as a piecewise trivariable polynomial. Its expression is so simple and the coefficients are decided by a linear system. Some numerical examples are presented to illustrate the method.
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    Cited: Baidu(1)
    Model Identification and Prediction Research of Medium and Long-term Hydrologic Forecast
    LU Jianfei;YU Jitao;CHEN Zishen
       2012, 51 (2): 107-112.  
    Abstract1217)      PDF (3382KB)(605)      
    Model identification of medium and longterm hydrologic forecast is studied in terms of pretreatment, data length and ways of modeling which are taken as primary factors for the prediction results. Based on finite sampling information criterion (FSIC), combined information criterion (CIC) is utilized to choose the proper order of the model. Kalman filtering is also used for nonlinear prediction. It is concluded that: 1) In model identification, reasonability of the pretreatment should be tested through the prediction results from the model if it significantly reduces the complexity of the model. 2) Data length of modeling should be long enough to reflect inherent oscillations of the time series while excessive amount brings in extra complexity, more time-consuming and less robustness. 3) Sliding model is better for larger flux and the streamflow peaks prediction, and sacrifices the precise of predicting relatively low run-off. 4) Kalman filtering used as a prediction method of runoff can remarkably raise the forecast effects in any sections of the range with the accuracy rate of peakprediction up to 63.64%.
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    Cited: Baidu(1)
    Proposing, Investigation and Practice on One-Node-AheadNumerical Differentiation Formulas
    ZHANG Yunong;CHEN Yuxi;CHEN Jinhao;YIN Yonghua
       2012, 51 (2): 1-5.  
    Abstract1201)      PDF (695KB)(601)      
    Based on the numerical differential theory, it is available to calculate the approximate first derivative of the target-node by using numerical differentiation formulas when the discrete sampling points of the unknown target function on specified interval are given. But for the target-nodes close to the boundary, it may be unable to use the center differentiation formulas involving multiple nodes because of the lack of sampling points on one side of the target-node. Besides, an accelerating change of the first derivative of the target-node may occur in some target functions. However, the use of forward/backward differentiation formulas simply takes the nodes on one side of the target-node into consideration, which probably makes the formulas difficult to adapt to such a change, and thus leads to less accuracy in estimating the first derivative of the target-node. Actually, for the target-nodes close to the right boundary, it is available to move the backward differentiation formulas one node ahead to calculate the first derivatives. Therefore, one-node-ahead numerical differentiation formulas are proposed and investigated. Experimental results verify and show that the first derivatives of the target-nodes with high computational precision can be obtained by using the one-node-ahead numerical differentiation formulas.
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    Theory Analysis of Wavelet Transform Denoising Algorithm for Stochastic Vibration Spectrum Estimation*
    LUO Zhongliang;WANG Huabin;CHEN Zhiming;YANG Faquan
       2012, 51 (2): 12-16.  
    Abstract1199)      PDF (1729KB)(581)      
    Stochastic vibration spectrum always contains sudden changes and discontinuance.On a wavelet denoising process, the soft-threshold method will make the estimation signal ambiguous at the discontinuity point, while the hard-threshold method will cause pseudo-Gibbs phenomena around the signal's discontinuity point. Through analysis on the statistic model of the stochastic vibration spectrum, a noise statistic model of numeric field vibration spectrum is established, and the nonlinear relationship between the filtering threshold-value and the wavelet transform scale is derived theoretically for providing a base for adaptive-threshold wavelet transform denoising. Finally,an universal adaptive denoising algorithm for vibration spectrum estimation based on wavelet transform is proposed. Simulation results show that the theoretical analysis is correct and the algorithm is good.
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    Hydrodynamic Mechanism of Morphology Revolution of the XiaomiaohongTidal Channel in Radial Sand Ridges,Jiangsu Province
    CHEN Kefeng;;LU Peidong;YU Guohua
       2012, 51 (2): 101-106.  
    Abstract1144)      PDF (11937KB)(577)      
    The comparison of the terrain data from the past 40 years shows that the inlet of the Xiaomiaohong channel has an evolutionary tendency of deposition in the north and erosion in the south. The north trough was silted constantly to disappear while the south trough developed adequately. The hydrodynamic mechanism of the change in deposition and erosion in different channels was discussed based on the analysis of field data and the tidal current Mathematical model. The reason that a state of deposition in the north and erosion in the south exists in the Xiaomiaohong channel during the past years is closely related to the tidal current characteristics in this area. The ebb flow discharge is stronger than flood in the south and middle waterways of the inlet, with an “ebb-dominated” style. On the contrary, the north waterway has a “flood-dominated” style. The sediment transportation shows a trend of northward inflow and southward outflow, consistent with the trend of deposition and atrophy in the north waterway and erosion and extension in the south waterway.
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    Self-similar solutions for the compressible Euler-Poisson equations in three dimension
    WANG Ling;XIA Li
       2017, 56 (1): 74-76.  
    Abstract218)      PDF (715KB)(562)      

    The isentropic compressible Euler-Poisson equations, addressed to describe the motion of ideal gaseous stars, consist of the Euler-Poisson equations for the conservation of mass and momentum, and Poisson equation induced by the potential function of the self-gravitational force. Using the separation method, self-similar solution are presented for the isentropic compressible Euler-Poisson equations in three dimension.

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    Studies on Interactions between Tie-2/VEGFR2 and Dihydroindazolocarbazole Dual Inhibitors via Molecular Docking
    TIAN Yuanxin;ZHANG Xianzuo;AN Linkun
       2012, 51 (2): 66-72.  
    Abstract1386)      PDF (2336KB)(556)      
    Dihydroindazolocarbazoles(DHI-carbazoles) are the potent dual inhibitors to VEGFR2 and Tie-2. In this work, the mechanism of interaction between VEGFR2/Tie-2 and DHI-carbazoles was performed with Surflex-dock. The results from molecular docking indicated that DHI-carbazoles competitively bound to the active site, which was the substrate ATP in VEGFR2/Tie-2 with high affinity. The differences of activity between VEGFR2 and Tie-2 resulted from the minor difference of active pockets. Hydrophobic effect played a key role in the formation and stability. Hydrogen bond and electrostatic effect also contributed to the difference. This work elucidated the antitumor mechanism of the DHI-carbazoles as a dual potent inhibitor and provided theoretical basis for the design of tyrosine kinase inhibitors.
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    Numerical simulation and analysis of saltwater intrusion to Modaomen waterway
    LIU Zufa;DING Bo;GUAN Shuai;CHEN Jichen;ZHANG Yonghua;YU Haixia
       2016, 55 (6): 1-9.  
    Abstract206)      PDF (6168KB)(538)      

    Saline water intrusions at Modaomen waterway were numerically simulated by using MIKE3 based on measured water levels and salinities in November 2006 and January 2007. Calibrated and validated model showed good fitness for both water level and salinity in case of prediction and observation with good detection indexes. The results indicated that salinity stratification, influenced by topography, diversion ratio and other factors such as tidal fluctuation change, resulted in water density difference and then produced extraordinary change in salinity vertical circulation. The change of salt flux is relative to the tidal flux, suggesting that tide is the carrier of brine.

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    The Number of Perfect Matchings in Six Types of Graphs
    TANG Baoxiang;REN Han
       2012, 51 (2): 40-44.  
    Abstract1009)      PDF (2181KB)(532)      
    It is an interesting and important problem to count the number of the perfect matchings in graphs, which origin from both physics and chemistry. So far, many mathematicians, physicists and chemists gave most of their attention to counting perfect matchings of graphs. But the problem of counting the number of the perfect matchings for general graphs is NP-difficult. By applying differentiation, summation and re-recursion calculation, the several counting formulas of the perfect matching for six specific types of graphs are given. As an application, the number of one type chessboard of the 1×2 dominoes covering is calculated.
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    Research on the Secondary Metabolites and Their Cytotoxic Activity of Mangrove Endophytic Fungus Nigrospora sp. from the South China Sea
    WEI Meiyan;LI Shangde;YUAN Ningning;LIANG Liping;SHE Zhigang;LIN Yongcheng
       2012, 51 (2): 59-62.  
    Abstract1558)      PDF (512KB)(521)      
    Research on the secondary metabolites of the mangrove endophytic fungus Nigrospora sp. from the South China Sea was reported. Three secondary metabolites were isolated from the ethyl acetate extract of the fermentation by silica gel column chromatography, preparative thin layer chromatography and recrystallgraphy. Their structures were identified by comprehensive spectroscopic methods as Griseofulvin (1), Vermixocin B (2),Tenellic acid A(3). The absolute configuration of compound 1 was further confirmed by singlecrystal X-ray analysis. The cytotoxic activity of compound 1in vitro was also evaluated, and compound 1 showed medium activity against KB,KBV200,and A549 cell lines with IC50 of 8.23, 9.10 and 14.26 μmol/L, respectively.
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