Table of Content

30 October 2019, Volume 25 Issue 5

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Unmanned Surface Vehicle

Research status and development trend of unmanned surface vehicle

Yan PENG, Lei GE, Xiaomao LI, Yuxuan ZHONG, Xin ZHANG

2019, 25(5):  645-654.  doi:10.12066/j.issn.1007-2861.2041

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Unmanned surface vehicle (USV), as an important branch of marine robotics, is a vehicle that operates on the surface of the water automatically, and it can be used for a wide range of military and civil purposes. Compared to other unmanned systems like unmanned aerial vehicle, unmanned ground vehicle and etc., research on USV is more challenging because of the harsh ocean environment and the special motion model of USV, such as high nonlinearity, strong time delay and time varying. This paper summarizes the research status and main achievements of unmanned ships from the aspects of situation awareness, path planning and guidance, and control, and it also describes at some length different development trends of unmanned ships at home and abroad. Finally, forecast on the development and application of unmanned ships in the future is made.

Dynamic collision avoidance for unmanned surface vessels under the uncertainty of obstacle velocity

Dong QU, Yan PENG, Huayan PU, Jun LUO, Chengyi HUANG, Jun KE

2019, 25(5):  655-667.  doi:10.12066/j.issn.1007-2861.2164

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The stability of collision avoidance is directly relate to the safety of unmanned surface vehicle (USV). However, the uncertainty of perception about the velocity of moving obstacles seriously undermine the stability of collision avoidance. Thus, an uncertain velocity obstacle (UVO) method is proposed to solve this problem. In order to improve the stability of collision avoidance at the macro level, an adaptive threshold-based closest point of approach (CPA) is adopted to assess collision risk while a boundary buffer is used to calculate the type of International Regulations for Preventing Collisions at Sea (COLREGS). To prevent changes in collision avoidance strategy, the UVO is modeled in velocity space of the USV, and a gradient descent method is used to determine local optimization of the cost function. Contrast experiments in simulation platform between UVO and VO indicate that the UVO has better performance on three indicators: strategy changes, success rate, and safe distance. Typical encounters such as head-on, crossing, and overtaking are conducted in sea trials. The USV successfully avoids each moving obstacle in the experiment. The results demonstrate the stability and safety of the UVO method.

Maritime ships detection for USV based on object proposals

Wei CHEN, Yi YANG, Xiaomao LI, Yuan LIU, Xin ZHANG

2019, 25(5):  668-678.  doi:10.12066/j.issn.1007-2861.1981

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Maritime ships detection is one of the main tasks in unmanned surface vehicle (USV)'s visual system. This paper proposes a kind of USV maritime ships detection algorithm based on object proposals. Firstly, a modified edge boxes algorithm is utilized to extract the edge information of the image, and an objectness score function is established to obtain object proposals. Secondly, a histogram of oriented gradient (HOG) feature model is built for the ship, and the support vector machine (SVM) is utilized to iteratively train a classifier by a bootstrap method. Finally, the feature descriptor of object proposals is fed into the classifier, and detecting the ship. In addition, the sea-sky line is utilized to further improve the detection performance of the algorithm based on the environment of USV. The experimental results show that the algorithm can rapidly and accurately detect the ship on the sea, and achieve a relatively high detection rate. And the algorithm has strong robustness to the change of the scale and the illumination conditions.

Research Paper

Video coding for 3D-HEVC based on saliency information and view synthesis prediction

Fang YU, Ping AN, Xule YAN

2019, 25(5):  679-691.  doi:10.12066/j.issn.1007-2861.1962

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To improve rate distortion performance, all standards of video coding emphasize reduction of information redundancy. However influences of human visual system (HVS) perception is often ignored. This paper proposes a video coding method for the latest standard 3D-high efficiency video coding (HEVC) based on human visual features. In this method, a 3D saliency model is first constructed. Different regions are coded according to their saliency information. The original view synthesis prediction (VSP) algorithm is improved to avoid boundary effects between depth blocks. The compressed video with new view-points is then generated using a proper rendering tool. Experimental results show that the proposed method can reduce the BD-rate by as much as 10% while maintaining the subjective quality. Peak signal to noise ratio (PSNR) of the obtained video is raised by 0.1 dB thus improving coding efficiency.

Reduced-reference quality assessment of stereoscopic images based on IGM and depth perception

Yun ZHU, Yongfang WANG, Yuan SHUAI

2019, 25(5):  692-700.  doi:10.12066/j.issn.1007-2861.1964

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In this paper, a reduced reference stereoscopic image quality assessment (SIQA) method is proposed based on the internal generative mechanism (IGM) and depth perception. The method determines 3D quality of experience (QoE) by focusing on image quality and depth perception quality. For image quality, a stereoscopic image is decomposed into a predicted portion and an uncertain portion according to IGM of the brain, handled with the metric based on gray level co-occurrence matrices (GLCM) and visual information separately. The depth perceptual quality is measured with an improved natural scene statistics (NSS) model. The image quality and depth perception quality are then integrated to obtain the overall quality. Experimental results show that the proposed metric outperforms the state-of-the-art metrics and is consistent to subjective ratings over widely used databases.

Location method based on improved Gaussian filter and adaptive estimation for weighted environment parameter

Yechen YANG, Yueli HU, Jie XU, Wenlong CHENG, Huaibo YU

2019, 25(5):  701-711.  doi:10.12066/j.issn.1007-2861.1990

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Location technology based on received signal strength indication (RSSI) ranging is a kind of low-cost location technology. In order to reduce the error of RSSI value due to environmental factors, this paper proposes an improved weighted Gaussian filtering algorithm which is used to deal with the RSSI value, and it also proposes an adaptive estimation algorithm for weighted environment parameter which is used to estimate the environmental parameters of the place where the mobile node to be located is. Then the path loss model is determined by the estimated environment parameters, and the location of the mobile node is estimated by the model. Experimental results show that the method can effectively improve the positioning accuracy of the system.

Fast pedestrian detection algorithm based on BING-casDPM

Yanwei HU, Meihua XU, Aiying GUO

2019, 25(5):  712-721.  doi:10.12066/j.issn.1007-2861.1988

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Pedestrian detection is a hot research field in computer vision technology, and it has important applications in automobile assisted driving and video surveillance. In view of the fact that traditional deformable part model (DPM) uses a sliding window for pedestrian detection and is time-consuming in the background area, a fast pedestrian detection algorithm based on BING-casDPM is proposed. Firstly, a cascaded support vector machine (SVM) classifier is trained based on the binarized normed gradients (BING) feature. The candidate areas containing all kinds of objects as seen on the test image are quickly calibrated through the classifier. Then, the detected box is extracted according to the characteristics of candidate windows, and finally pedestrians are accurately detected from the detected box using casDPM model with the result being returned to the original image. The experiment results show that the algorithm proposed in this paper is about 16 times faster than the classical DPM model, and about 40% faster than the casDPM model in terms of the speed of detection when detection rate remains stable.

Communication emitter identification under square integral bispectra and semi-supervised discriminant analysis

Guochuan HAN, Jinyi ZHANG, Ke LI, Likang HE, Yuxi JIANG, Tao WANG

2019, 25(5):  722-732.  doi:10.12066/j.issn.1007-2861.1991

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This paper is an attempt towards coping with the problem that the methods of traditional communication emitter identification with the same model performs poorly with extracting fingerprint feature and acquiring high accuracy recognition when the priori label information is insignificant. Targeting the same manufacturer, same batch and same type communication emitter identification of small fingerprint feature difference, an efficient algorithm based on square integral bispectra and semi-supervised discriminant analysis is proposed for communication emitter identification. This algorithm uses square integral bispectra for the extraction of the communication emitter signal bispectra feature as the fingerprint feature, which represents the communication emitter. Simultaneously, for the purpose of improving communication emitter identification recognition performance, the semi-supervised discriminant analysis algorithm is employed to map high dimensional bispectra feature data to a low dimensional subspace and identify in the low dimensional subspace by the nonlinear manifold information and partial label information of bispectra feature data. In order to verify the effect of the proposed algorithm, the same manufacturer, same batch and same type FM radios, as representative communication emitter with the same model, are used here to perform identification experiment. Experiment results show the highest recognition rate of proposed method for test sample is up to 87.6% when the labeled training FM radio samples are limited, which points to the effectiveness of this algorithm in extracting fingerprint feature and recognition accuracy on same type communication emitter identification.

Event semantic representation for news texts

Xianchuan WANG, Zongtian LIU

2019, 25(5):  733-741.  doi:10.12066/j.issn.1007-2861.1989

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Event, as a larger knowledge unit than "concept", is more consistent with human understanding process. Treating event as the core knowledge unit in news texts and applying the Neo-Davidsonian event semantic and 6-tuple event model theory, this paper proposes a new strategy for event representation. It is suggested that by extending some operators the action, object, tense and environment of the event and all the other fuzzy information modifying the event become known. And with the employment of the description logic method, the features of the news object in the event and event relations are represented effectively. The given instances indicate that this approach is good and effective for representing events and event relations in news texts.

Design and experiment of TMR-based voting system for TOP

Cong PENG, Yunfu SHEN

2019, 25(5):  742-753.  doi:10.12066/j.issn.1007-2861.1960

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Reliability in the design of computer processor is essential. This paper focuse on designing a triple module redundancy (TMR) photoelectric voting system for the ternary optical processor (TOP). The photoelectric voters for TOP process units are presented. Steps for implementing the voting framework are illustrated. A voting experiment for TOP of 1-bit is carried out, where 108 voting examples are designed and executed. A reliability analysis of $m$-bit reconfigured operators is briefly discussed. Experimental results and reliability analysis show that the TMR voting scheme for TOP can improve operating efficiency and reliability of the system.

Laser-induced aggregation of Rayleigh granular jets

Zhenyu NIU, Zhewei ZHOU, Kai HUANG, Jinsong ZHANG, Jianhua ZHANG, Zhiliang WANG

2019, 25(5):  754-766.  doi:10.12066/j.issn.1007-2861.1954

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Dynamic convergence and stability characteristics of Rayleigh particle jets under laser irradiation are studied. Laser technology has widely applications in particle operation at micro-nano scales such as optical tweezers. While researches of particle behavior under laser irradiation generally focus on optical mapping and measurement of the particle population characteristics, laser-induced particle dynamical behaviors are rarely studied. Based on the analysis of granular gas dynamic simulation and the flow instability theory, the two cases of rarefied granular jet (point source) and granular jet are investigated. For point sources, that laser is effective in making the particle distribution more concentrated in the space by comparing with the classical vacuum deposition theory is found. In the case of granular jet, simulation and theoretical analysis show that the light scattering force can suppress instability of the long and short wavelengths, and effectively gather nanoparticles into jet.

Properties of a new magnetic biological patch

Kai YANG, Ning PEI, Qixin WANG, Lanlan CAI

2019, 25(5):  767-775.  doi:10.12066/j.issn.1007-2861.1961

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A new non-toxic magnetic biological patch had been designed for implant assisted-magnetic drug targeting. The structure and properties of the MBP were characterized. In vitro experimental results showed that the ferric oxide particles could be captured effectively around MBP when it was placed in the uniform magnetic field. Effects of the distance between fluid and MBP, and magnetic flux density on the accumulation of the ferric oxide particles attracted by MBP were investigated in vitro. Accumulation of ferric oxide particles decreased rapidly with the increasing distance between fluid and MBP. Accumulation of ferric oxide particles first increased and then decreased with increment of magnetic flux density of the uniform magnetic field. Experiment results were explained by numerical analysis using Software Ansys.

Mechanism of capacity degradation of β-NaMnO₂ as cathode material for sodium ion battery

Chenzi LIU, Yemin HU, Wenxian LI, Yang LIU, Pengfei HU, Hongming JIN, Mingyuan ZHU, Ying LI

2019, 25(5):  776-785.  doi:10.12066/j.issn.1007-2861.1959

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Due to its easy synthesis process and high theoretical capacity, layered $\beta $-NaMnO$_{2}$ is considered as a potential cathode material in sodium ion battery. However, studies on its capacity degradation in the first several cycles are rare. In this article, $\beta $-NaMnO$_{2}$ was prepared by a solid state method, which had a high initial discharge capacity of 184 mA$\cdot$h/g at 10 mA/g with a capacity retention of 73% after 10 cycles. The mechanism of capacity degradation was investigated based on X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectroscope (XPS). Phase transformation was recorded by XRD in the first three cycles, showing appearance of Na$_{0.91}$MnO$_{2}$ and Na$_{0.7}$MnO$_{2}$ in the discharge process with low crystallinity instead recrystallization of NaMnO$_{2}$. The proportion of disorder structure increased upon Na$^+$-ion extraction, associated with a loss of crystallinity as evidenced by HRTEM observation. XPS further explained the valence variation of Mn in different phases in the cycling.

Bending of Timoshenko beam with arbitrary stepped cross-section

Xiao YANG, Cheng QIAN, Xuewei QIAN

2019, 25(5):  786-795.  doi:10.12066/j.issn.1007-2861.1974

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Bending deformation of a Timoshenko beam with arbitrary stepped cross-section and elastic support on boundaries was investigated. Based on the Heaviside function, analytical closed-form solutions of the deflection and rotational angle of the Timoshenko beam with arbitrary stepped cross-section subject to transverse load was derived. On this basis, the bending behavior of clamped and cantilever Timoshenko beams with single and double stepped cross-sections was analyzed numerically. Influences of location and quantity of the cross-section change, span-height ratio of the beam as well as stiffness of the boundary supports on the bending of the Timoshenko beam were examined. It is shown that there exist major differences of deflections and rotational angles between a Timoshenko beam with stepped cross-section and a Timoshenko beam with constant cross-section. Although deflection of the Timoshenko beam with stepped cross-section is smooth, there exists evident jump of the slope of the rotational angle of a Timoshenko beam with stepped cross-section at the location of the cross-section change.

Experimental comparative study of new lock enhanced integral geocell and geogrid mesh elements reinforced foundation

Zhiheng DAI, Mengxi ZHANG, Juan HOU, Jiazheng LI

2019, 25(5):  796-806.  doi:10.12066/j.issn.1007-2861.1975

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This paper presents results of laboratory model tests carried out on strip footings supported on geosynthetic reinforced sand beds. The relative performances of different forms of geosynthetic reinforcement (i.e. new lock enhanced integral geocell and geogrid mesh elements) foundation beds are compared using the same quantity of reinforcement in each test. Pressure-settlement curves, surface settlement and heave, deformation of two form geocells and glide planes are analyzed to understand the mechanism of different soil foundations. It is found that both form of geocells can decrease settlement and increase bearing capacity of the foundation. Vertical confinement of geocells is due to friction between the infill material and the geocell wall, which restrains soil from moving outside. The geocell-reinforced base can thus provide lateral and vertical confinement, tensioned membrane effect, and wider stress distribution, resulting in a better performance. The experiment also shows that geogrid mesh elements are more advantageous than new lock enhanced integral geocells. It is provided that there is no rupture of the material during loading. However, some ruptures can be found in joints of new lock enhanced integral geocells, which in turn principally decreased bearing capacity of the foundation. Meanwhile, significant observations on the difference in reinforcement mechanism for different forms of geocells are also presented.

Integrated dynamic inventory and pricing based on product lifecycle learning

Junjun GAO, Yu CHEN

2019, 25(5):  807-816.  doi:10.12066/j.issn.1007-2861.1995

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An integrated decision model of dynamic pricing and inventory is established by incorporating product lifecycle learning into demand management for fashion products. Suppose a retailer places an order with reference to the demand forecast made through product lifecycle estimation before the sales season. Then, in the sales process, product lifecycle learning is reflected in updating the real sales data. And based on the learning result, both the inventory replenishment decision and dynamic pricing decision are made. Specifically, this integrated decision model is used in a footwear supply chain for sensitivity analysis on initial selling and price elasticity, and the result shows that the decision model is an effective solution for fluctuation of demand in the supply of fashion products.

Empirical study on the influencing factors of labor migration: a case study of Shanghai

Chen WEI, Lu ZHEN, Qiangyuan CHEN

2019, 25(5):  817-825.  doi:10.12066/j.issn.1007-2861.1992

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It is a common phenomenon in labor migration that a large proportion of the labor force now flows into large and medium-size cities. As one of the most important cities in China's economic construction, Shanghai is a good subject for the study of labor migration. A three-stage research on labor migration in the field of economics has been conducted to establish a labor migration model for first-tier cities. When applying the Probit regression method from the dimension of individual characteristics, family characteristics and the characteristics of the inflow cities/provinces, a conclusion can be drawn as follows: education, nationality, foreign language ability, personal income, number of family members and household consumption all have a significant impact on labor migration decision-making. It is of great significance to the reasonable transfer of labor force within the whole society and the optimal allocation of labor force resources when much attention is paid to the difference between the individual characteristics, family characteristics and the characteristics of the inflow cities/provinces.

Promoting mechanism in college students' innovative undertaking based on evolutionary game

Yang HUANGFU, Liying YU

2019, 25(5):  826-835.  doi:10.12066/j.issn.1007-2861.1986

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Governments and universities are two important stakeholders in the process of college students' innovative undertaking. Under the condition of information asymmetry and bounded rationality, the model of governments, universities and college students is constructed based on the evolutionary game. The model studies choices of the three stakeholders in the process of college students' innovative undertaking. The evolutionary equilibrium strategy of the model with different parameters is demonstrated using the Matlab software. The research results show if the government wishes to promote college students' innovative undertaking, large investment alone is not enough. It must take into account the efficiency of college students' innovative undertaking and set to mobilize the enthusiasm of all parties involved. The university, as the main body in education, also has its own role to play in the trio-relationship, which is, to set clear responsibilities for different parties and improve in spection and supervision mechanism. On the part of the students, it is obvious that the greater the number of the college students who involve themselves in innovation and entrepreneurship, the more conducive to the formation of innovative and entrepreneurial mechanism.

A modeling and solution method for cash transportation vehicle routing from the perspective of workload balancing

Mingkun LI, Gaoshuai BAI, Xinying JIANG

2019, 25(5):  836-850.  doi:10.12066/j.issn.1007-2861.1993

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This paper explores the vehicle routing problem for cash transportation by taking into account the workloads and costs. A real case in Shanghai is studied, and various factors, e.g. traffic jams are considered. In order to obtain a satisfactory solution, this paper has tested with the Solomon insertion heuristic algorithm, the neighborhood search heuristic, and the non-dominated sorting genetic algorithm-Ⅱ (NSGA-Ⅱ). Simulation studies indicate that the neighborhood search heuristic outperforms the Solomon algorithm and NSGA-Ⅱ when the speed of vehicles keeps changing under undesirable traffic conditions. But for instances with good traffic conditions, the NSGA-Ⅱ generates a better result. Other aspects of the problem are also discussed for the purpose of offering suggestions and practicable method for decision making of practitioners and researchers.

Applications of combined photothermal and photodynamic effects of graphene quantum dots in antibacterium

Ying WU, Yuliang GUO, Zefei ZHANG, Xin GUI

2019, 25(5):  851-858.  doi:10.12066/j.issn.1007-2861.1965

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As a class of excellent antibacterial materials, graphene and its derivatives have attracted much research attention. As an important member of the graphene family, however, graphene quantum dots (GQDs) is mainly focused on drug delivery, cancer treatment and biological testing. In this study, GQDs was prepared to kill Escherichia coli ($E.$ $coli$) under 655-nm laser irradiation. GQDs was synthesized from graphite powder. Under the laser irradiation, the as-synthesized GQDs rapidly converted the laser energy to heat and produced reactive oxygen species. Escherichia coli incubated with 0.6 mg/mL of GQDs was completely killed after 15 min of irradiation, while the Escherichia coli growth was not affected by GQDs or laser alone. With huge surface area used for loading considerable drugs, excellent biocompatibility, solubility and stability, GQDs may be a potential antibacterial material.