Table of Content

31 December 2018, Volume 36 Issue 6

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Optical Fiber Sensors Technology

Fiber Tip Integrated Airy Beams Based on Surface Plasmon Polaritons

GUAN Chun-ying, SHI Jin-hui

2018, 36(6):  879-893.  doi:10.3969/j.issn.0255-8297.2018.06.001

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Due to small cross section and flexibility of optical fber, lab on tip requires no strict spatial collimation and coupling, therefore has many advantages including high integration, flexible operation, and performance stability. Here we review basic principles, generation and optimization of plasmonic all-fber single and double Airy beams. Various Airy beams have been achieved from metallic slits and grooves on the fber end based on FIB milling. The compact all-fber integrated special beam shaping devices are of importance to realize all-fber optical trapping, microparticle manipulation, and beam shaping.

Communication Engineering

Implementation of Distributed Antenna System with Software-Defned Radio

LUO Jia-xing, CHEN Wei-gang, YANG Jin-sheng

2018, 36(6):  894-903.  doi:10.3969/j.issn.0255-8297.2018.06.002

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To utilize the spatial diversity effectively for combating the fading caused by the multipath propagation, a distributed antenna system based on a software-defned radio platform is designed and implemented. Compared with traditional schemes, the system converges the data received by each front-end to another computer, which can equalize the computation load among different computers and is suitable for the software-defned radio architecture. Specifcally, software-defned radio platforms consisting of four computers and universal software radio peripherals (USRP) are used as inner receivers at different positions. In this paper, through a switch, the four inner receivers are connected to an extra computer which is used as an outer receiver for signal decoding and other operations. Besides, superframe number is delivered in the idle bits of transport parameter signaling to achieve the synchronization between inner receivers and outer receiver. The scheme achieves distribution processing of inner receivers and the outer receiver with the capability of realizing the space diversity and the computing balance, accordingly, performing good practicability and expansibility. The test results in the practical wireless scenario show that the distributed antenna system can achieve the spatial diversity and improve the overall performance compared with a single receiver.

Performance Analysis of Distributed Massive MIMO Systems under RF Mismatch

WEN Ben-ben, LIU Tao, WANG Hao

2018, 36(6):  904-913.  doi:10.3969/j.issn.0255-8297.2018.06.003

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The performance analysis of the distributed massive multiple-input multipleoutput (MIMO) system under the mismatch of the radio frequency (RF) circuits is studied. Based on the performance analysis and the principle of max ratio transmission (MRT), a closed-form expression of achievable downlink rate is derived. The result of simulation validates that the RF mismatch on base station (BS) can be well evaluated with this expression. If the amplitude variance of RF gain is more than 1 dB or the phase of RF mismatch is more than π/2 on BS, the maximum of the achievable downlink rate loss of users is ffty percent larger than a system with ideal RF. The system performance is seriously affected by the RF mismatch, which verifes that the performance analysis for the RF mismatch is indispensable.

Invulnerability Analysis of Electric Power Optical Transmission Network in Smart Grid Based on Complex Networks

SUN Na, XIA Zheng-yun, SHI Jian-qiang, CHEN Dian-xin, LU Min, XU Hai-yang

2018, 36(6):  914-924.  doi:10.3969/j.issn.0255-8297.2018.06.004

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In order to improve the invulnerability of electric power optical transmission network in the smart grid, experimental simulations of random attacks and selective attacks on electric power optical transmission network in Jiangbei District of Nanjing City are carried out based on complex network theory. A method of improving the invulnerability of the network is proposed according to the simulation results. In the experiment of random attacks, we investigate the impact of single node failure on network connectivity and screen the hub nodes, and get the hub nodes that need to be protected. In selective attacks, two kinds of attack strategies are proposed, namely, network efciency relative loss rate frst attacks and real-time betweenness frst attacks. The invulnerability of the network is evaluated from three aspects including connectivity, network efciency, and network efciency relative loss rate. The experimental results show that the electric power optical transmission network has the worst invulnerability to real-time betweenness frst attacks. On this basis, an important node evaluation and protection method is proposed to improve the invulnerability of electric power optical transmission network, and the feasibility and effectiveness of the proposed method is verifed by the example simulation.

Vehicle-Mounted Database Based Switching Algorithm by Using Cooperative Trigger Mechanism for LTE-R of High-Speed Train

CHEN Pan, HU Zhao-wen, LIAO Cong-wei, LUO Heng, DENG Lian-wen

2018, 36(6):  925-935.  doi:10.3969/j.issn.0255-8297.2018.06.005

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It is of signifcant importance to further improve the channel switching performances of high-speed railway. In this paper, a new long term evolution for railway (LTE-R) switch algorithm for high-speed train is proposed based on the vehicle-mounted database and the signal power measurement. The comparison result between the information of eNodeB stations(BS)along the railway and the real-time measurement is used for switching trigger judgment of database. The simulation result shows that the proposed algorithm can achieve the fast reconnection after interruption and switch locking. The switching trigger efciency ratio of the proposed algorithm is 43.7% higher than that of the conventional algorithm on several key points of overlap region. And the handover success rate reaches as high as 0.995. The cooperative triggering algorithm is promising for extensive applications in the high-speed railway network LTE-R.

Signal and Information Processing

High-Speed Dynamic Three-Dimensional Shape Measurement

WANG Jian-hua, YANG yan-xi

2018, 36(6):  936-949.  doi:10.3969/j.issn.0255-8297.2018.06.006

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Aiming at the 3D surface measurement of the fast changing object of which surface satisfes the continuity assumptions, a method that wrapped phase demodulating based on two-dimensional wavelet transform and phase unwrapping based on least square method is proposed. Its advantage is that, frstly, only one fringe pattern can be projected to reconstruct the shape of object, so high-speed dynamic 3D measurement can be realized. Secondly, compared with Fourier transform proflometry, two dimensional wavelet transform proflometry has better noise suppression ability. Thirdly, the least square phase unwrapping method has good robustness, unwrapping phase is smooth. The computer simulation compares the results of wrapped phase demodulating by the Fourier transform, the one dimensional and two dimensional wavelet transform, the performance of three different mother wavelet and several spatial phase unwrapping methods, and the dynamic ellipsoid, continuous convex surface and dynamic water ripple are simulated or tested respectively, and the results show the effectiveness of the method proposed in this paper.

Measurement Method of Torsion of Helicopter Rotor Blades Based on Stereo Vision

XIONG Bang-shu, LUO Yuan-hua, HUANG Jian-ping, LI Xin-min

2018, 36(6):  950-957.  doi:10.3969/j.issn.0255-8297.2018.06.007

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A method based on stereo vision is proposed to accurately measure the torsion of helicopter rotor blades and to simplify the operational process. First, three-dimensional coordinates of the circular markers in the camera coordinate are obtained by using the binocular stereo vision technique. Second, the rotor coordinate is established by the threedimensional coordinates of the markers which are measured when the blades are horizontally straight during low-speed rotation. Finally, the torsion of blades is calculated by the threedimensional coordinates of the markers which are obtained during low-speed rotation and high-speed rotation on the blades in the rotor coordinate. The method proposed in this paper is proved to be effective and accurate by a number of experiments and data analysis on measurement of the torsion of rigid blades. It also shows advantages of non-contact detection, dynamic measurement and easy operation.

Effect of Human Activities and Association Rules Mining on Spatiotemporal Evolution in Jianghan Lake Group

FENG Wan-shu, FENG Cun-jun, CHEN Jiang-ping

2018, 36(6):  958-968.  doi:10.3969/j.issn.0255-8297.2018.06.008

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Lake is an important component of water resources. Lakes have two statusesexpanding and shrinking in the process of evolution, which and lead to neat changes in the area of lakes are the product of bidirectional changes caused by the evolution of the lakes. Taking Jianghan Lakes clusters as an example, the study conducts an analyzes sis of the correlation between distribution and evolution of lakes and human activities from 1984 to 2014. The results show that implementing the project of "returning farmland to lakes" played a positive role in protecting and recovering the lakes after the flood of 1998. In addition, spatial autocorrelation analysis and hot spot detection method were are introduced to explore the temporal and spatial evolution of lakes. The study carries out a hot-spot detection of lake shrinking showing conspicuous characteristics of aggregation by comparing spatial correlation between lake expanding and lake declining in recent 30 years to locate lake shrinking cluster area, and and further the forming reasons are further exploreds their forming reasons. At last, the study delves into the association rules between socio-economic factors and distribution and shrinking of lakes. By exploring the socio-economic regular patterns contained in the evolution of lakes, the decision-making assistance of ecological protection and restoration in Jianghan Basin can be summed up. The results show that lake distribution area is often accompanied by aggregation of population with agricultural yields, especially productivity of aquatic products, at the forefront in the region. But with the advancement of modernization and the adjustment of agricultural structure, primary industry, especially the growth of the fshing industry shows a weaken dependence on local lake resources. Lake shrinking mainly happens in rural areas featuring traditional extensive mode of production., And and rapid expansion of agriculture within a short time is generally at the cost of the overexploitation of lake resources.

Application of PSInSAR in Monitoring Land Subsidence in Yanshan Mining Area

MA Fei-hu, JIANG Shan-shan, SUN Cui-yu

2018, 36(6):  969-977.  doi:10.3969/j.issn.0255-8297.2018.06.009

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Persistent scatterer InSAR (PS InSAR) is capable of detecting a certain number of persistent scatterers (PS) by analyzing the stability of amplitude and phase of images covering the same area. The persistent scatterers are used to model and analyze the deformation of target areas. Taking the Yanshan, an important metal mining area in Shangrao of Jiangxi Province, as an experimental area, this paper took 18 sentinel-1A images from 2016-08 to 2017-03 to analyze land subsidence caused by mining based on PSInSAR. Experimental results show that there is a heavy subsidence in Yongping Copper Mine. The maximum land subsidence velocity of Yongping Mine is -90 mm/y, and the area subsidence takes the similar distribution with the mining distribution. The area bound by Yiyang County and Hengfeng County has a weaker subsidence, with subsidence velocity of -20 mm/y. The experiment shows that PSInSAR is effective in monitoring metal mining area.

Monitoring and Analysis of Trafc Network Accessibility of the Yangtze River Economic Zone

LI Wei-qing, DU Jing, ZHANG Xuan, TIAN Zhong

2018, 36(6):  978-986.  doi:10.3969/j.issn.0255-8297.2018.06.010

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There is no accurate monitoring and evaluation for current accessibility states of the transportation infrastructure in the Yangtze River economic zone. By referring the results of the frst national geographic census in 2015, the monitoring results of basic national geographical state in 2016, and the related socio-economic data, this paper proposes a method for monitoring the accessibility of trafc network in the Yangtze River economic zone. The changes of transportation network accessibility within the Yangtze River economic zone from 2015 to 2016 are analyzed with this method. The study results indicate that the accessibility level of the core transportation network in the Yangtze River economic zone is consistent with the economic level of the cities of the zone. Moreover, the accessibility of the core transportation network has gradually spread from the original capital cities to peripheral cities, accordingly, peripheral cities can develop to a better level of accessibility through their own advantages. Each peripheral area with good accessibility can serve as a central point and gradually become a core area.

Computer Science and Application

Optimal Operation of Household Water Heater Based on Nash Bargaining

CHI Zhong-jun, WAN Qing-zhu, CHEN Ya-lan, SUN Jian, GU Jun, ZHANG Miao, WANG Xin

2018, 36(6):  987-995.  doi:10.3969/j.issn.0255-8297.2018.06.011

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Demand response is an embodiment of the smart grid flexible interactivity. It has a broad application prospect in energy saving, peak clipping and valley flling. Household water heater in demand response has a great potential of optimal operation. However, in the demand response process of water heater, the weight between electricity cost and water temperature is difcult to determine. This paper proposes a household water heater optimization method based on the Nash bargaining. The water temperature and the electricity cost are considered as the two sides of game theory. The Nash equilibrium solution, which determines the water heater operation plan, is obtained by using Nash bargaining. Simulations show that the proposed method can effectively optimize the running of water heater and keep the balance between electricity cost and water temperature at the same time.

Shift Scheduling Based on Fatigue and Routing Capacity Limitation in Contact Centers

LI Jun-xiang, WANG Xiao-na

2018, 36(6):  996-1009.  doi:10.3969/j.issn.0255-8297.2018.06.012

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In evaluation of the service efciency of a contact center, besides the customer satisfaction, the turnover rate of agents is also a major concerned index of the contact center among operation and management. To reduce the turnover rate of agents in contact centers, we establish a shift scheduling model about agents by considering the agent's fatigue, multiskill agents, multi-channel service and the limit of agent-skill and task-channel routing capacity which is caused by the actual operations situation of the majority of current contact centers. By solving the model, we give the optimal scheduling scheme to reduce the work fatigue of agents as much as possible under the given stafng level in contact centers. Finally, by adopting the LINGO language we apply the model to some contact centers to analyze the data and verify the correctness and validity of the model by comparing with other scheduling schemes. The model not only provides an effective scheduling solution to contact centers, but also plays important reference to other service felds.

Environmental Anomaly Detection Method during Crop Growth Based on Distributed Clustering

YU Yue, DENG Li, PANG Hong-lin, FEI Min-rui

2018, 36(6):  1010-1021.  doi:10.3969/j.issn.0255-8297.2018.06.013

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In order to process the massive agricultural environmental data stored in distributed system and improve the production efciency, the clustering algorithm based on Gaussian Mixture Model (GMM) is modifed in this paper. Based on this, an environmental anomaly detection method during crop growth is proposed. Under the Spark distributed computing framework, frstly, a pre-clustering algorithm is adopted to initialize the models. Secondly, Spark is utilized to update the models iterationally until it gets stable. In each iteration, Map phase distributes sample points to the models, Reduce phase renews the numbers of models and parameters. Finally, the detection of environmental anomaly is completed by taking advantages of the clustering result. The experimental results show that this approach is practically feasible and effective.

Control and System

Dual Adaptive Control for a Class of Mixed Uncertainty Systems

SHANG Ting, QIAN Fu-cai, LIU Lei, HU Shao-lin

2018, 36(6):  1022-1030.  doi:10.3969/j.issn.0255-8297.2018.06.014

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For the linear quadratic Gaussian (LQG) problems with unknown constant parameters and accurately measurable state, the separation theorem is no longer valid due to the coupling between parameters estimation and control gain, which lead to the failure to the analytical solution of the control law. The dual adaptive control method is proposed in this paper, where a state space model of parameters estimation is established, control gain is obtained by rolling dynamic programming, Kalman flter is used to estimate unknown parameters, the present difculties about the mutual coupling between estimated gain and control gain are overcome, and the controller with suboptimal characteristics is designed. On the one hand, the controller can optimize the control target, on the other hand, it can also learn unknown parameters effectively. The simulation results show the effectiveness of the proposed control algorithm.