2017 Vol.23

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Dynamic obstacle avoidance for USV based on velocity obstacle and dynamic window method ZHANG Yangyang, QU Dong, KE Jun, LI Xiaomao Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 1-16.   DOI: 10.3969/j.issn.1007-2861.2016.07.021 Abstract （2223）      PDF（pc） （16419KB）（1210）       Knowledge map    Save Velocity obstacle is a dynamic obstacle avoidance algorithm widely used on an unmanned surface vehicle (USV). However, traditional velocity obstacle does not consider the effect of USV’s kinematics and obstacle’s motion information error, and does not know when to start and terminate avoidance. Based on velocity obstacle, USV and obstacle are represented by an ellipse. A method for solving ellipse tangent is proposed. Considering the kinematics performance of USV, a dynamic window method and velocity obstacle are combined. Only the speed and course that the USV can reach in a given time are used in calculation. By comparing the collision time and the time required for the USV to finish avoidance to determine when to start avoidance, a method to terminate obstacle avoidance is proposed. A virtual obstacle method is then proposed to reduce influence of obstacle’s motion information error. Feasibility and effectiveness of the method are verified by simulation. Reference | Related Articles | Metrics | Comments（0）

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Complete coverage path planning of USV used for mapping round island ZHONG Yuxuan, GE Lei, ZHANG Xin, PENG Yan, YANG Yi, LI Xiaomao Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 17-26.   DOI: 10.3969/j.issn.1007-2861.2016.07.020 Abstract （1629）      PDF（pc） （3863KB）（372）       Knowledge map    Save When mapping the seabed around islands independently, there are difficulties like large amount of calculation and complex task scene for mapping with an unmanned surface vehicle (USV). To solve the problems, an algorithm composed of a dynamic grids algorithm for main motion direction and a heuristic search algorithm is proposed. This algorithm establishes an environmental model based on the dynamic grids algorithm. The heuristic algorithm based on priority is used to choose an appropriate path point to travel. When the USV getting into a deadlock, an optimal path is generated with the heuristic search algorithm to get out. Simulation results show that performance of path planning is improved with the proposed algorithm. The planned path is more reasonable and effective to meet the needs when using USV to map the seabed around an island. Reference | Related Articles | Metrics | Comments（0）

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3D Lidar-based marine object detection for USV LI Xiaomao, ZHANG Xin, WANG Wentao, QU Dong, ZHU Chuan Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 27-36.   DOI: 10.3969/j.issn.1007-2861.2016.07.022 Abstract （2197）      PDF（pc） （9428KB）（650）       Knowledge map    Save To realize autonomous navigation and avoidance, it is necessary for an unmanned surface vehicle (USV) to perceive the surrounding environment in real time, and detect obstacles threatening its sailing. Three dimensional Lidar plays an important role in unmanned system obstacle detection. In this paper, an obstacle detection algorithm based on 3D Lidar is proposed. The 3D laser point cloud is projected onto a 2.5D grid map in one period. The obstacles are clustered and segmented. The elliptical feature of obstacles is extracted from the raw laser point. Dynamic obstacles are found and tracked using the nearest neighbor data association and a Kalman filter. The simulation data based on the electronic chart verifies effectiveness of the method in USV obstacle detection. Reference | Related Articles | Metrics | Comments（0）

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Design of a seawater sampling and docking ransmission device YANG Chao1, GUO Weiqi2, JIN Zuowen3, YANG Yi4, LI Xiaomao4, LIU Mingque4, PENG Yan4 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 37-46.   DOI: 10.3969/j.issn.1007-2861.2016.07.008 Abstract （966）      PDF（pc） （6655KB）（199）       Knowledge map    Save To solve the docking problem of seawater sampling from lifting multi-bottle ampling arrays to storage and distribution, a set of design schemes for seawater transfer ocking device according to seawater sampling requirements is proposed. The docking ransmission device is composed of an upper fixed joint and a lower docking seat, where compressed guide claws surrounding the upper joint contact the lower cone, making a ough claws-cone docking mechanism and compensating rod and cone docking of the second ine docking of the positioning error to lessen the positioning accuracy requirements. The echanical structure ensures to meet the requirements of O-ring assembly in the seawater eccentric flow channel from the samplers to the distribution system. To eliminate the influence f variations in the docking process, the axial displacement and radial eccentricity are ompensated by the flexible connection of the orrugated pipe. The purpose is to prolong he service life of the device. Based on the SolidWorks Motion simulation, the centering rocess of the whole docking system is simulated to reveal influence of various kinds of ariations on the docking mechanism. The stress state of the guide claw in the docking rocess is simulated with SolidWorks Simulation, showing rationality of the structure design. Reference | Related Articles | Metrics | Comments（0）

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Sea-sky line detection based on structured forests edge detection and Hough transform XU Liangyu1, MA Lukun1, XIE Xie1, PENG Yan1, PENG Yanqing2, CUI Jianxiang1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 47-55.   DOI: 10.3969/j.issn.1007-2861.2016.07.018 Abstract （1866）      PDF（pc） （20904KB）（556）       Knowledge map    Save The sea-sky line is an important feature in the sea-surface environment image, and detection of the sea-sky line is essential in dividing the sea and sky, and detecting the coastline area and objects. This paper provides a method to detect the sea-sky line using structured forests edge detection and Hough transform. The method uses a Gaussian low-pass filter to reduce the influence of regional textures such as wave texture and light reflection. A trained structured random decision forest is then used to label each pixel, and binarize it to determine whether it belongs to an edge or not. Hough transform is used to fit the sea-sky line more accurately. Experimental results show that this method can neglect clutter edge, greatly improve edge detection, and effectively extract sea-sky lines from a complicated sea-sky background with high robustness and accuracy. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(2)

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Design and implementation of USV simulation system HU Xinming1, ZHANG Xin1, ZHONG Yuxuan1 PENG Yanqing2, YANG Yi1, YAO Junfeng1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 56-67.   DOI: 10.3969/j.issn.1007-2861.2016.07.019 Abstract （1328）      PDF（pc） （7648KB）（278）       Knowledge map    Save Offshore commissioning for unmanned surface vehicle (USV) is costly, difficult and inefficient. To reduce the workload of sea tests, a simulation system is designed for test and analysis of USV control systems, and a simulation process is programed. The simulation system includes five modules. The display and control module is used for global path planning and comprehensive information monitoring. The data simulation module simulates data of sensors for obstacle detection and positioning. The obstacle process module preprocesses, rasterizes, clusters and fits the detected data, and tracks moving obstacles. The navigation and obstacle avoidance module is made of line of sight (LOS) and an elliptical clustering-cone deduction algorithm. The cascaded generalized predictive control-proportion-integral-derivative (GPC-PID) method is used in the motion control module. Every simulation module is independent, and can be switched according to different requirements. The simulation results show that the described design of the simulation system for USV is accurate and reasonable. Reference | Related Articles | Metrics | Comments（0）

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A preconditioning iterative algorithm for eigenvalue problem of symmetric tensor GU Chuanqing, LI Long Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 68-72.   DOI: 10.3969/j.issn.1007-2861.2016.07.009 Abstract （786）      PDF（pc） （491KB）（178）       Knowledge map    Save Shifted symmetric high order power method (SS-HOPM) is a well-known iterative algorithm for solving tensor Z-eigenvalue. In this paper, the Newton method is used to deal with the initial condition of the algorithm. A Newton preconditioning SS-HOPM(PSS-HOPM) for the symmetric tensor eigenvalue problem is obtained. Two numerical examples are used to illustrate that, compared with the SS-HOPM algorithm, this algorithm can calculate more eigenvalues with little increase of computation time. Reference | Related Articles | Metrics | Comments（0）

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Determination of Ostwald coefficient in silicone oil XU Yi1, XU Yanyan1, YUAN Bin2 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 73-80.   DOI: 10.3969/j.issn.1007-2861.2015.04.011 Abstract （772）      PDF（pc） （3589KB）（294）       Knowledge map    Save With eco-friendliness and excellent electrical insulation properties, silicone oil has attracted widespread attentions in industries, especially as China is currently increasing investments in power construction. In this paper, the Ostwald coefficient of dissolved gas in silicone oil treated as insulting oil for transformers based on well-developed gas chromatography techniques is tested. Multiple sets of paralleled Ostwald coefficients of silicone oil are obtained, and it is believed that it can be used for testing parameters of silicone oil for transformer insulation. Reference | Related Articles | Metrics | Comments（0）

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Combined system for biogas production using kitchen wastes and recycled water MA Zhen1, WAN Hao2, ZHANG Meng2 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 81-90.   DOI: 10.3969/j.issn.1007-2861.2015.04.010 Abstract （754）      PDF（pc） （4174KB）（254）       Knowledge map    Save Regarding the current situation of treatment of kitchen wastes and sewage in colleges, constructing a combined energy-saving system to produce biogas using kitchen wastes and recycled water is proposed. The two recycling systems have a complementary relation. It can provide a new mode of energy-saving work in general, and for colleges in particular. Different mixing ratios of kitchen wastes and sludge are considered in the experiment of biogas production. With the ratio of 1:1, the cumulative yield of biogas reaches a maximum value. The cumulative biogas yield for 40 days is 621 mL/(g·VS), the removal rate of volatile solid (VS) is up to 67.5% and efficiency of methane production is 78.6%. The removal efficiencies of solluted chemical oxygen demand (SCOD), soluble carbohydrate and protein after the reaction by mixed substrate of 1:1 are 55.7%, 68.7%, and 22.7%, respectively. The pH values of the substrate is between 6.8 and 7.2. According to an estimation of energy saving in the South Campus of Shanghai University, the program can save energy costing 260 000 RMB every year after reconstruction, making a good economic benefit. Reference | Related Articles | Metrics | Comments（0）

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Target-screening of eight organic chloride compounds in chemical agents of liquid oil fields using gas chromatography and mass spectrometry HU Zhimeng1, XIA Lingyan2, SHAO Hongyun2, JIANG Shaohui2, ZHAO Junqiao2, ZHENG Kewen1, CHEN Zheng1, REN Guofa1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 91-100.   DOI: 10.3969/j.issn.1007-2861.2015.03.015 Abstract （609）      PDF（pc） （9350KB）（163）       Knowledge map    Save A method is proposed to target-screen the eight organic chloride compounds in chemical agents of liquid oil fields using gas chromatography and mass spectrometry(GC/MS). Parameters affecting both extraction and instrumental analysis are studied. Under optimal conditions, the linear range is from 2 to 100 ng/μL for the target compounds. The correlation coefficient R is above 0.99 for the analytes with the 1imit of detection(LOD) ranging from 10 to 120 ng/mL. Good recovery, ranging from 77.2% to 93.5% with relative standard deviation (RSD) less than 7%, has been achieved in the matric spiking experiments. The established method is applied to target-screen the eight organic chloride compounds in a mixed sample of chemical agents of liquid oil fields provided by the Shengli Oilfield Corporation. However, no target compound is detected in the sample. Reasons for such result are given in the paper. Reference | Related Articles | Metrics | Comments（0）

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Pollution characteristics, source identification and health risk assessment of PAHs in road dust LI Hong, SHEN Xinhao, WANG Yujie, TANG Liang, WU Minghong, MA Jing Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 101-111.   DOI: 10.3969/j.issn.1007-2861.2015.03.017 Abstract （1442）      PDF（pc） （8867KB）（229）       Knowledge map    Save A total of 112 road dust samples from Shanghai urban areas were collected with a mesh point method to investigate road dust in Shanghai. Levels of polycyclic aromatic hydrocarbons (PAHs) and their potential risks to human health were assessed, and source contributions to road dust PAHs were identified. This paper is focused on 16 the United States Environmental Protection Agency priority PAHs, concentrations of  PAHs in summer samples ranging from 0.817 ng/g to 21.800 μg/g with a mean of 10.400 μg/g, and in winter samples ranging from 4.08 μg/g to 59.90 μg/g with a mean of 23.70 μg/g. Difference of PAHs in road dust samples taken from functional areas between summer and winter shows that the total PAH concentrations at transportation hubs, construction areas  and commercial districts are high, while offshore region , green areas and open territory have a low level. Differences exist in main sources of road dust in summer and winter using a characteristic ratio method. However, the health risk assessment for both children and adults exposed to road dust in summer and winter indicates that  Cancer risk is less than 10−6, without posing a potential cancer threat. In addition, the incremental lifetime cancer risk (ILCR) of PAHs in road dust in winter is significantly higher than that in summer, and ILCR of PAHs in road dust for adults is higher than for children. Reference | Related Articles | Metrics | Comments（0）

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Determination of 30 halogenated hydrocarbon compounds in soil with head space solid phase micro-extraction and gas chromatography PEI Yongqiang, FAN Zhanchun, ZHAO Jing, YUE Jianwei, LI Yongqing, LI Huanfeng Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 112-120.   DOI: 10.3969/j.issn.1007-2861.2015.03.012 Abstract （614）      PDF（pc） （10273KB）（147）       Knowledge map    Save This paper studies an analytical technique of 30 halogenated hydrocarbon compounds in soil using a method of head space solid phase micro-extraction (HS-SPME), and analyzes influencing factors of target extraction efficiency. As a result, optimum extraction conditions are determined within 0.25~50.0×103 ng/L, with good linearity. The detection limit is 0.04~3.58×103 ng/kg. Blank standard addition recovery is 62.7%~122.0%, and relative standard deviation (RSD) is 0.7%~14.9%. Reference | Related Articles | Metrics | Comments（0） Cited: Baidu(1)

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Shear strength of unsaturated Nanyang expansive soil and its prediction SUN Hongyun, SUN Dean Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 121-127.   DOI: 10.3969/j.issn.1007-2861.2015.01.018 Abstract （725）      PDF（pc） （7567KB）（249）       Knowledge map    Save Expansive soil is a problematic soil with swelling and shrinkage. Compared with ordinary clay, the strength is clearly affected by water content. To investigate the effect of water content on the strength of expansive soil, a series of direct shear tests on Nanyang expansive soil with different water contents were carried out. Relationship between shear strength and water content at the same dry density was obtained. Test results show that the shear strength and cohesion decrease with increasing water content, and the internal friction angle changes little. In addition, by introducing macro saturation into the Bishop’s equation for unsaturated soil, the results show that the modified strength equation can well predict strength of unsaturated expansive soil. Reference | Related Articles | Metrics | Comments（0）

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Biaxial bending of rectangular plates with different modulus ZHANG Liangfei, YAO Wenjuan Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 128-137.   DOI: 10.3969/j.issn.1007-2861.2015.02.003 Abstract （681）      PDF（pc） （3085KB）（176）       Knowledge map    Save An eutral axis can be considered from two bending directions to solve the biaxial bending problem of rectangular plates with different modulus. Based on the different modulus theories, an equation of the neutral axis location is derived using the static equilibrium equation of rectangular plates with different modulus. The deflection curve equation is solved with the Kantorovich method. Its solution agrees well with the finite element solution. The result shows that the classical shell theory is not applicable in calculating deflection of a rectangular plate when tensile and compressive modulus are quite different. The proposed method provides an approach to analyze the bending problem of other structure forms of plate with different modulus, and theoretical reference for engineering applications. Reference | Related Articles | Metrics | Comments（0）

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Estimation algorithm of sampling clock frequency offset for OOFDM system based on training sequence ZHANG Zhen, SONG Yingxiong, ZHANG Junjie, DUN Han, GUO Songlin, XUE Ziwei Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 138-146.   DOI: 10.3969/j.issn.1007-2861.2015.02.011 Abstract （1346）      PDF（pc） （9872KB）（222）       Knowledge map    Save This paper studies sampling clock synchronization for optical orthogonal frequency division multiplex (OOFDM) systems, and proposes a simple sampling clock frequency offset (SCFO) estimation algorithm for hardware implementation based on crosscorrelation properties of the training sequence. The main idea is as follows. First, correlation between the received training sequence and the known training sequence is obtained, and then sampling clock frequency offset found with a few adders and one divider based on the property that an additional sampling point is introduced when the cross-correlation value periodically changes a cycle. An optical OFDM system with intensity-modulation and direct-detection (IMDD-OFDM) is set up to show performance of the algorithm. Experimental and simulated results indicate that the algorithm has good accuracy and noise immunity. Reference | Related Articles | Metrics | Comments（0）

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A novel tri-section SIR dual-band filter with high stopband rejection JIANG Yifei1,2, MENG Lingqin1,2, YANG Guangli1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (1): 147-154.   DOI: 10.3969/j.issn.1007-2861.2015.01.019 Abstract （829）      PDF（pc） （6005KB）（945）       Knowledge map    Save A dual-band filter with high stopband rejection is designed using a tri-section signal to interference ratio (SIR) resonator. The center frequencies and first spurious frequencies of resonators can be controlled independently to design aspecific dual-band filter. The tri-section coupling structure is aimed at transmission zeros and high stopbands rejection. To get a high external quality factor, an inter-digital finger coupling structure is introduced. The filter has dual passband center frequencies of 1.57 GHz (GPS) and 2.5 GHz (4G), with 3 dB fractional bandwidths of 4.0% and 2.4%, respectively. Measured results well agree with simulations. Reference | Related Articles | Metrics | Comments（0）

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Telocytes involvement in recovery after myocardial infarction Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 155-160.   DOI: 10.3969/j.issn.1007-2861.2017.02.004 Abstract （738）      PDF（pc） （1337KB）（228）       Knowledge map    Save Myocardial infarction (MI) is a disorder that lowers the lifespan and quality of life. Reperfusion treatment as early as possible is the most effective solution, with an increased focus on post-MI medication. In the recovery process after MI, telocytes (TCs) appear to play an important role, which develops a large number of questions awaiting answers. Defining possible signaling mechanisms involved in recovery after MI may lead to identification the limits of current therapies, and development of new therapeutic solutions. Reference | Related Articles | Metrics | Comments（0）

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Exosomes in the precision diagnosis and treatment of cancer HU Muren1, CHEN Ting2, YANG Changqing3, GE Bujun1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 161-168.   DOI: 10.3969/j.issn.1007-2861.2017.02.003 Abstract （997）      PDF（pc） （636KB）（390）       Knowledge map    Save Exosomes are nanoscale vesicle with a double lipid membrane structure, and can be secreted by almost all types of cells. Exosomes can carry nucleic acids and proteins, and play important roles in a variety of physiological and pathological processes especially in cell communication and signal transduction. Tumor cell-derived exosomes have been proved to be involved in the regulation of tumor growth, invasion and metastasis process. Exosomes’ roles in the early diagnosis, prognosis prediction and therapeutics have been a hot topic. This review summarizes the role of exosomes in the development and metastasis of cancer, and its potential function in the individually precise treatment. Reference | Related Articles | Metrics | Comments（0）

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Advancement of photosensitizers for photodynamic therapy HAN Xiaobo, ZHENG Yinghong, YANG Liming Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 169-178.   DOI: 10.3969/j.issn.1007-2861.2017.01.007 Abstract （2744）      PDF（pc） （2514KB）（957）       Knowledge map    Save This paper reviews the main types of photosensitizers in photodynamic therapy(PDT). PDT has been widely used in the treatment of tumors and non neoplastic diseases since its invention. In a photochemical reaction, a material is called photosensitizer if it can be activated by light with energy transferred to reactants without reaction. Photosensitizer is an important impact factor in PDT, and its research progress is important in the development of PDT. Photosensitizer has three generations: the first dominated by hematoporphyrin derivative, the second represented by porphyrin and porphin, and the third being modification of the second generation chemical groups. After decades of development, chemical properties of photosensitizer has become stable with less side effects. Reference | Related Articles | Metrics | Comments（0）

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A GMRES-Inout algorithm for computing PageRank problems GU Chuanqing, SHAO Chenchen Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 179-184.   DOI: 10.3969/j.issn.1007-2861.2016.07.010 Abstract （777）      PDF（pc） （520KB）（240）       Knowledge map    Save The PageRank algorithm for determining the importance of Web pages has become a central technique in Web search. Based on the inout method, a GMRESInout algorithm which modifying the inner-outer method preconditioned with the restarted GMRES algorithm is proposed. Description and convergence analysis of the proposed algorithm are given. Numerical results are reported to demonstrate the efficiency of the proposed algorithm. Reference | Related Articles | Metrics | Comments（0）

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Properties of polysulfonamide fiber (PSAF)/polytetrafluoroethylene (PTFE) composites LIU Liqi, WANG Xu, XIE Wang, YU Mingming, FANG Lin, LI Hong, YANG Min, XIAO Yi, REN Musu, SUN Jinliang Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 185-191.   DOI: 10.3969/j.issn.1007-2861.2015.05.017 Abstract （1394）      PDF（pc） （3763KB）（266）       Knowledge map    Save Polysulfonamide fiber (PSAF)/polytetrafluoroethylene (PTFE) composites were prepared by hot pressing process. The effect of PSAF on material mechanical properties, thermal stability, structure and morphology was studied with thermal gravimetric analyzer(TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and thermal field scanning electron microscope (TFSEM). The results show that PSAF can improve mechanical properties of the composite materials, and the composites have good thermal stability. A moderate amount of PSAF can be well dispersed in the PTFE matrix. Bonding of the PSAF and PTFE matrix interfacial is good, and there is a physical adhesion. Reference | Related Articles | Metrics | Comments（0）

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Influence of roasting condition on purification of iron oxide by magnetic separation SUN Xiaowu, WANG Xingqing, TANG Xiaoquan, SHU Shuqi Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 192-200.   DOI: 10.3969/j.issn.1007-2861.2015.04.013 Abstract （665）      PDF（pc） （3859KB）（218）       Knowledge map    Save Scale on the surface of iron in incinerated municipal solid waste scrap as raw materials was purified by roast magnetic beneficiation to produce iron oxide up to industry standard. The effects of reduction roasting, magnetic field strength, particle size and other test conditions on magnetic beneficiation were researched. The results show that magnetite powder with TFe content of 67.61% and 85.17% iron recovery can be obtained by secondary magnetic separation under the conditions of reduction temperature of 750 ℃, reduction time of 60 min, charcoal ratio of 7% and magnetic field strength of 0.10 and 0.08 T, respectively. Reference | Related Articles | Metrics | Comments（0）

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Experiment of memory space move technique for double-space storage ZHAN Haojun, JIN Yi, OUYANG Shan, SHI Yeqiang Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 201-215.   DOI: 10.3969/j.issn.1007-2861.2015.01.017 Abstract （715）      PDF（pc） （21788KB）（149）       Knowledge map    Save This work presents an emulation experiment for double-space storage principle and the memory space move technique. The experiment validate feasibility of using nonvolatile random access memory (NVRAM) to build a double-space storage and correctness of the memory space movement technique. The experiment system consists of an 8086CPU, 16 MB double-space storage, and sixteen 8-bit move latches. Two unmovable and fourteen movable window frames are set up. The first instruction and initial program are set in the 255th window that cannot be closed. An interrupt vector table and a move vector table are set in the 254th unclosed window. It has been make sure that the 8086CPU is booted properly, and the initial program, interrupt service routine, read and write memory instruction are executed correctly. Further, access to the 8086CPU’s 1 MB memory can be automatically transformed to the 16 MB double-space memory unit, and the move latches can be modified to map the window frame into a new window wall of the double-space storage. The experimental results lay a foundation for the double-space memory principle and its memory space move technique. Reference | Related Articles | Metrics | Comments（0）

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A circular oscillation mechanism with adjustable amplitude KE Xianxin, XIN Jizhong, YANG Yang Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 216-224.   DOI: 10.3969/j.issn.1007-2861.2015.02.008 Abstract （1024）      PDF（pc） （14648KB）（282）       Knowledge map    Save As the currently developed oscillation mechanism generally does not have adjustable amplitude, a circular oscillation mechanism with adjustable amplitude is designed. It contains an eccentric motion mechanism and an adaptive dynamic balance mechanism. Dynamic simulation and analysis are carried out on the eccentric motion mechanism. Experimental results show that 0~50 mm adjustable amplitude and 2~36 rad/s adjustable oscillation frequency can be achieved simultaneously. Unbalance quality of the table causing adverse effects can be compensated by the adaptive dynamic balance mechanism to increase life of the die. Its oscillation amplitude can be changed easily, conveniently and quickly, with simplicity, compact mechanism, rigid connection, strong bearing capacity and easy maintenance. It is expected to be used widely in biological engineering. Reference | Related Articles | Metrics | Comments（0）

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Torsional vibration and vibration suppression in power drives YANG Ying, YU Yanpu, HUANG Rui, HAN Bing Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 225-234.   DOI: 10.3969/j.issn.1007-2861.2015.03.009 Abstract （1103）      PDF（pc） （7004KB）（320）       Knowledge map    Save Torsional vibration causes oscillation and increases mechanical transmission wear. It is a main constraint in improving dynamic performance of drive systems. A parallel resonant circuit theory is used to analyze the mechanism and energy transfer process during torsional vibration. With a quality factor for assessing the degree of harm, torsional torque caused by torsional vibration harmonic content is quantitatively calculated, showing that a large inertia load leads to a great degree of torsional vibration damage, and even a small harmonic torque can cause torque of several dozens of times as large. Torque feedback is introduced to inhibit torsional vibration, and a design method of torque observer with limited bandwidth is presented. The torque feedback control based on observer can raise the resonant frequency. A sensitivity analysis is done for some critical system parameters. The analysis and simulation studies show that the proposed method can suppress resonance. Reference | Related Articles | Metrics | Comments（0）

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Distribution and toxic effects of polybrominated diphenyl ethers (PBDEs) in organism XU Bentuo, WU Minghong, XU Gang Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 235-243.   DOI: 10.3969/j.issn.1007-2861.2015.04.012 Abstract （950）      PDF（pc） （1508KB）（354）       Knowledge map    Save Polybrominated diphenyl ethers (PBDEs) are a kind of fire retardant that exists widely in the living environment. PBDEs become a major focus in the environmental science due to the pollution problem. This paper introduces distribution of PBDEs in organism and toxic effects including thyroid toxicity, nervous system toxicity, hepatotoxicity, reproduction and development of toxicity and immune toxicity. The corresponding toxicity mechanism is discussed, providing practical and reliable theoretical supports of biology effect caused by PBDEs, and drawing the public attention to this kind of fire retardant. Reference | Related Articles | Metrics | Comments（0）

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Intelligent remote planting system based on cloud platform GUO Peng1, LI Jun2, ZHANG Haiyan3 Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 244-251.   DOI: 10.3969/j.issn.1007-2861.2016.02.021 Abstract （1534）      PDF（pc） （10833KB）（229）       Knowledge map    Save To solve the problem of lack of time and experience, a leisure agricultural garden is designed. Users can plant remotely by means of cloud computing. Intelligent planting using an expert decision system can also be achieved based on fuzzy control. Using fuzzy clustering and adaptive neuro-fuzzy inference system (ANFIS) to explore the user’s planting data, private ordering of expert decision system can be obtained. Experimental results show that the designed system is effective and reliable. Reference | Related Articles | Metrics | Comments（0）

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Super cyclically edge connected graphs with two orbits of the same size JIANG Haining Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 252-256.   DOI: 10.3969/j.issn.1007-2861.2016.05.004 Abstract （872）      PDF（pc） （451KB）（258）       Knowledge map    Save For a graph G, an edge set F is a cyclic edge-cut if (G−F) is disconnected and at least two of its components contain cycles. If G has a cyclic edge-cut, it is said to be cyclically separable. The cyclic edge-connectivity is cardinality of a minimum cyclic edgecut of G. A graph is super cyclically edge-connected if removal of any minimum cyclic edge-cut makes a component a shortest cycle. Let G = (G1,G2, (V1, V2)) be a doubleorbit graph with minimum degree δ(G) ≥ 4, girth g ≥6 and |V1| = |V2|.  Suppose Gi is ki- regular, k1 ≤ k2 and G1 contains a cycle of length g, then G is super cyclically edge connected. Reference | Related Articles | Metrics | Comments（0）

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Tri-integrable couplings of Dirac hierarchy and its bi-Hamiltonian structure LI Qian1,2, XIA Tiecheng1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 257-266.   DOI: 10.3969/j.issn.1007-2861.2015.04.022 Abstract （753）      PDF（pc） （501KB）（267）       Knowledge map    Save Tri-integrable couplings of Dirac hierarchy are obtained based on the enlarged zero curvature equation from semi-direct sums of Lie algebras. Its bi-Hamiltonian structures are then established with variational identity. Reference | Related Articles | Metrics | Comments（0）

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Common least-squares solution to some matrix equations Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 267-275.   DOI: 10.3969/j.issn.1007-2861.2015.02.012 Abstract （665）      PDF（pc） （222KB）（357）       Knowledge map    Save Necessary and sufficient conditions are derived for some matrix equations that have a common least-squares solution. A general expression is provided when certain resolvable conditions are satisfied. This research extends existing work in the literature. Reference | Related Articles | Metrics | Comments（0）

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An exponent deviation integral algorithm for mixed integer programming YU Yaru, YAO Yirong Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 276-289.   DOI: 10.3969/j.issn.1007-2861.2015.05.010 Abstract （844）      PDF（pc） （582KB）（292）       Knowledge map    Save This paper studies an exponent deviation integral approach to the mixed integer programming problem. A deviation integral function with good properties is proposed, and the optimality condition for a mixed integer programming problem is examined. Then an exponent deviation integral algorithm is developed. Numerical calculation is performed using the Monte-Carlo technique to show effectiveness and feasibility of the algorithm. Reference | Related Articles | Metrics | Comments（0）

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Circadian rhythm in mammal based on phase synchronization FAN Qingduan1,2, LIU Zengrong1,3 Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 290-297.   DOI: 10.3969/j.issn.1007-2861.2015.02.005 Abstract （978）      PDF（pc） （6703KB）（241）       Knowledge map    Save A collective rhythm emerges in suprachiasmatic nucleus (SCN) of mammals hypothalamus, controlling the central nervous system and peripheral tissues. To explore the emergence of circadian rhythms, a modified Kuramoto model of the SCN network is established, and its phase synchronization is analyzed. The results show that emergence of circadian rhythm is expressed by phase synchronization. The effect of parameters on order parameter is studied, showing agreements with biological facts. This study provides insights of the mechanism of circadian rhythm. Reference | Related Articles | Metrics | Comments（0）

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Flexural behavior of RC beams strengthened with near surface mounted CFRP strips ZHANG Zhimei, ZHANG Zhenbo, HUANG Haitao, ZHANG Zhenkai, XIONG Hao Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 298-307.   DOI: 10.3969/j.issn.1007-2861.2015.02.002 Abstract （701）      PDF（pc） （4300KB）（170）       Knowledge map    Save This paper uses the finite element software ABAQUS for nonlinear finite element analysis of the flexural behavior of reinforced concrete (RC) beams with near-surface mounted (NSM) carbon fiber reinforced polymer/plastic (CFRP) strips. Through simulation of 5 beams with NSM CFRP strips from the test, the experimental and theoretical results were compared to verify accuracy of the model. Using the verified finite element model, the influence of factors were analyzed such as FRP length, groove number, reinforcement method and longitudinal reinforcement ratio on the flexural behavior of RC beams. The results show that the CFRP length and longitudinal reinforcement ratio have a larger impact on the flexural behavior of the RC beams, while the impacts of groove number and reinforcement method are limited. This paper also proposes a boundary reinforcement quantity formula for CFRP strips. Reference | Related Articles | Metrics | Comments（0）

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Warning classification of public crisis in a university with improved fuzzy TOPSIS based on α level sets XU Yang, YU Liying, LIN Chenyan Journal of Shanghai University（Natural Science Edition）    2017, 23 (2): 308-314.   DOI: 10.3969/j.issn.1007-2861.2015.02.010 Abstract （626）      PDF（pc） （811KB）（249）       Knowledge map    Save In managing public crisis in a university, it is critical to evaluate warning classification of public crisis. This paper manifests that the warning classification can be measured by elements of crisis itself and the crisis management. Specifically, crisis elements include impact, hazard intensity and proliferation. The crisis management elements include crisis awareness, tolerance and crisis management. Taking these into consideration, a warning classification evaluation system for public crisis in a university is conducted, which has fifteen indexes. Besides, an improved fuzzy technique for order preference by similarity to an ideal solution (TOPSIS) based on level sets is proposed for the warning classification evaluation. Finally five university crisis events are chosen for case analysis. Reference | Related Articles | Metrics | Comments（0）

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Group-based vintage film inpainting using robust principal component analysis YU Bing1,2, DING Youdong1,2, DONG Sun1,2, HUANG Xi1,2 Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 315-323.   DOI: 10.12066/j.issn.1007-2861.1923 Abstract （1103）      PDF（pc） （11530KB）（218）       Knowledge map    Save In this paper, a new group-based method using robust principal component analysis (RPCA) is proposed to deal with multiple categories of damage in vintage film sequences. Pre-processing of the video sequence is achieved by shot segmentation and flicker elimination. In a framework of multi-resolution pyramid, an observation matrix is constructed on the coarsest level by space-time domain grouping. After performing RPCA transform based on the alternating linear method in sequence, locations of large area damage are obtained based on inter-frame error information. An initial inpainting result sequence, a break mask sequence, and a nearest neighbor offset matrix set using an upsampling method are constructed. The original sequence is then modified. By repeating the space-time grouping RPCA transform, inpainting of the vintage film sequence is realized. Experimental results show that the method can simultaneously repair different damages in the screen with good performance. Reference | Related Articles | Metrics | Comments（0）

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Evaluation criteria for visual comfort in 3D-VR TIAN Feng1,2, XU Haojun1, WANG Pan1, HOU Xiaofei1, HUA Minlei1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 324-332.   DOI: 10.12066/j.issn.1007-2861.1936 Abstract （1029）      PDF（pc） （18973KB）（152）       Knowledge map    Save With development of the virtual reality (VR) technology, 3D-VR video has become a hot spot. 3D-VR video is taken with multiple cameras, which would lead to color differences in some parts of the screen. The differences in hue, saturation and lightness of the left-right parallax that affecting audience comfort are quantitatively analyzed. In a subjective evaluation experiment, a relationship model between 3D-VR texture difference and comfort is built based on HSL (hue, saturation, lightness) color space. With the model, a visualization early warning platform of VR video texture is development to help artists in the 3D-VR content production and creation. Reference | Related Articles | Metrics | Comments（0）

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Reduction of background audio noise for historical films based on non-negative matrix factorization ZHANG Yejun, YANG Weiying Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 333-341.   DOI: 10.12066/j.issn.1007-2861.1940 Abstract （1071）      PDF（pc） （8374KB）（156）       Knowledge map    Save Audio materials of numerous historical films suffer from low sound quality, noise and other problems after being archived for a long time. This paper proposes a method based on non-negative matrix factorization (NMF) to automatically detect and separate background noise in a single channel audio. Harmonic signals and noises are modeled and differentiated using a sinusoid model and a priori noise training model respectively. Background noise is separated from the input audio with a constrained NMF algorithm. Experiments show that the proposed denoising algorithm outperforms the current algorithms in the denoise plug-in. Reference | Related Articles | Metrics | Comments（0）

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Survey of VR applications in interactive films and games ZHANG Tingting1, TIAN Feng1,2, Lü Wei3, WANG Yihua4, HUANG Chao1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 342-.   DOI: 10.12066/j.issn.1007-2861.1935 Abstract （1611）      PDF（pc） （23502KB）（326）       Knowledge map    Save Virtual reality (VR) is an important technology widely applied in interactive film and video games. Due to its immersive sense, interactivity and conception, virtual reality has changed the industry of interactive film and video game, and significantly improves the user experience. This paper briefly summarizes the state-of-the-art applications in film and video games industry including short films, documentaries, promos, games, educational applications, medicine, psychological interaction, etc. According to interaction level, applications of VR can divided into panoramic interactions, plot interactions, and complete interaction. The bottlenecks of VR interactive contents and the problems of current VR technology including the bottlenecks of VR films, the problems of current VR games and VR devices and analyzed. Finally, prospects of possible developments of VR in the future are given. Reference | Related Articles | Metrics | Comments（0）

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Automatic annotation for film and Television drama shots and recut system based on face identification LANG Yue1, ZHOU Jiting1, LIANG Xiaolong2, ZHANG Wenjun1 Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 353-363.   DOI: 10.12066/j.issn.1007-2861.1713 Abstract （1263）      PDF（pc） （6062KB）（345）       Knowledge map    Save This paper proposes an automatic editing system named Star Cut based on face recognition using deep learning and a video shot detection technique. The purpose is to establish a system for management, retrieval, and automatic recut of film and TV shots. First, the system with over 350 faces of pop stars and actors using a U-face model is trained to learn facial features. The system uses the change rate of edges to detect shot edge. After shot segmentation, the system uses the pre-trained face models to identify faces in the input film or TV drama shot by shot. Users can either choose to recognize all figures in these shots or just choose selected one to recut all the shots containing him/her together automatically. The recall rate of shot segmentation is above 95%, and the recognition rate of faces in an shooting angle of 45° is 92.45%. Test results show that the proposed system has good robustness. Reference | Related Articles | Metrics | Comments（0）

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Survey on visual comfort of 3D movies DAI Shuaifan1, TIAN Feng1,2, HUANG Chao1, TANG Haifeng3, Lü Wei4 Journal of Shanghai University（Natural Science Edition）    2017, 23 (3): 364-377.   DOI: 10.12066/j.issn.1007-2861.1941 Abstract （850）      PDF（pc） （25147KB）（155）       Knowledge map    Save Visual comfort is important in stereoscopic 3D experience. The influence of visual comfort can be categorized into psychological and physiological factors. Existing work focuses on visual fatigue factor analysis, comfort evaluation and comfort enhancement of 3D movies. Based on the related research, this paper summarizes the factors of visual fatigue, reviews various measurement methods proposed to evaluate visual comfort, and provides an overview of recent advances in improving 3D image quality. Finally, this paper previews the future work for visual comfort of 3D movies. Reference | Related Articles | Metrics | Comments（0）

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