Table of Content

30 September 2018, Volume 36 Issue 5

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Optical Fiber Sensors Technology

Progress in Microstructure Fiber-Based SPR Sensor

WEI Yong, SU Yu-dong, LIU Chun-lan, ZHANG Yu, LIU Zhi-hai, YUAN Li-bo

2018, 36(5):  723-747.  doi:10.3969/j.issn.0255-8297.2018.05.001

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Fiber-based surface plasmon resonance (SPR) sensor is the extension and development of the traditional prism-based SPR sensor. Two bottlenecks limit the application of fiber-based SPR sensors:the testing sensitivity is relative low and it is difficult to perform the multichannel sensing detection. In recent years, we explore a SPR sensing technology based on the micro-structured fiber, and construct various micro-structured fiber-based SPR sensors, which break through the current two problems:improving the detecting sensitivity and performing the multi-channel measurement of biochemical sensing. The utilization of microstructure fibers for SPR sensors contributes to reducing the size of the sensing system greatly, ensuring the convenience of integrating with the optical fiber system. In summary, the microstructure fiber-based SPR sensors have a broad application prospects.

Graphene/Au Thin Film Coupled Microfiber All-Optical Modulator

LI Qin-you, ZHOU Ai, GUO Dong-lai

2018, 36(5):  748-755.  doi:10.3969/j.issn.0255-8297.2018.05.002

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An all-optical modulator is fabricated with sandwich structure of graphene/Au thin film coupled microfiber. The whole structure is sealed by polydimethylsiloxane (PDMS). The Au film can confine the evanescent field and enhance the interaction between evanescent field and graphene. This device exhibits strong optical polarization and saturation absorption effect, resulting in a polarization extinction ratio of up to 42.3 dB at 1 550 nm. Because the S-polarization light exhibits more intensive interaction with graphene, the modulation effect can be enhanced when pump and signal both are in S-polarization. The experimental result shows that a high modulation amplitude of 41.0 dB can be reached with a 130 mW pump light at 980 nm, whereas the 3 dB and 10 dB modulation amplitudes correspond to pump lights of 2.8 mW and 5.6 mW, respectively.

Communication Engineering

Acquisition of Indoor Laser Point Clouds Based on Mobile and Terrestrial Scanning

MO You, ZHONG Ruo-fei, ZHANG Zhen-xin

2018, 36(5):  756-764.  doi:10.3969/j.issn.0255-8297.2018.05.003

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An indoor point clouds data acquisition and application method based on the integration of indoor mobile and terrestrial laser scanning technology is proposed, in order to solve problems in data acquisition of indoor mobile mapping systems, such as some important areas but with insufficient density or missing data. Firstly, the indoor mobile mapping systems was integrated for quickly obtaining the indoor three-dimensional (3D) laser point clouds, based on the indoor localization technology combined with odometer and inertial navigation. Then, the advantages of terrestrial laser scanning technology, which is superiority on the density of the point clouds, is taken for completing data registration between the indoor mobile and terrestrial laser scanning system. The effectiveness of the proposed method is experimentally verified by 3D modeling and error analysis. The experimental results show that the method could obtain the refined point clouds data quickly and solve the problems of less data density and missing data effectively, accordingly improving the reliability and integrity of model building of indoor refined point clouds.

On Resource Management in Vehicular Ad Hoc Networks: Multi-parameter Fuzzy Optimization Scheme

ZHANG Yu-ting, ZHAO Hai-tao, TANG Zi-hao, ZHU Hong-bo

2018, 36(5):  765-773.  doi:10.3969/j.issn.0255-8297.2018.05.004

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Large amount of information like text, audio and video exists in vehicular ad hoc networks (VANETs). However, the highly dynamic network feature and the limited memory of the local server pose challenges to resource management, leading to the failure of resource presentations for users, moveover the transmission of the invalid fragment data would also result in the significant waste of the precious bandwidth and memory. To solve this problem, this paper proposes an improved fuzzy logic resource management (FLRM)-multi-parameter fuzzy logic resource management (MP-FLRM). In this scheme, we firstly gather and record the request time, download time and upload time for each resource by the designed vehicle to infrastructure (V2I) communication mode. Then survival time can be reached after defuzzifier of multi-parameters thus, used for updating the resource list in real time. Simulation results show that MP-FLRM will improve the system throughput, accordingly, enhancing the system performance.

Non-stationary MIMO Channel Modeling and Parameter Evolving Under 3D Scenarios

JIANG Kai-li, CHEN Xiao-min, ZHU Qiu-ming, HU Xu-jun, CHEN Bing

2018, 36(5):  774-786.  doi:10.3969/j.issn.0255-8297.2018.05.005

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Due to the rapid movement of transmitter and receiver, the propagation channel of mobile communication system performs non-stationary characteristics. A new nonstationary multiple-input multiple-output (MIMO) channel model between base station and mobile station under three dimensional (3D) scenarios is proposed. The new model takes the continuity of fading phase into account and guarantees more realistic Doppler frequency. Meanwhile, an extended 3D time evolving algorithm of channel parameters, including birth-death processes of clusters, path delays, path powers and angles of arrival and departure, is given and analyzed. Simulation results demonstrate that our channel model can characterize the properties of non-stationarity and the time-variant autocorrelation function (ACF) and cross-correlation function (CCF) in a good consistence with theoretical ones, and is applicable to the performance evaluation and validation of wireless mobile system under time-variant 3D scenarios.

Three-Phase Single Harmonic Detection without Phase Locked Loop

LI Wen-juan, SHAO Xue-xin, BAO Han, XU Wei

2018, 36(5):  787-797.  doi:10.3969/j.issn.0255-8297.2018.05.006

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The accuracy of traditional single harmonic detection method performs overdependency performance of PLL. When the network voltage distorts, the PLL will get wrong phase information. In this paper, a three-phase single harmonic detection method without phase locked loop is proposed to address this problem. By distinguishing the positive sequence components of the supply voltage by means of mathematical analysis, the voltage phase information can be precisely obtained. This method performs optimizes the function of PLL. In addition, the feasibility of the improved single harmonic detection method under the condition of three-phase voltage distortion is verified by principal analysis. And the detection accuracy of single phase harmonic detection without phase locked loop is simulated on PSCAD/EMTDC simulation plattorm. Finally, an experimental platform is built and experimental results prove the reliability of the proposed method.

Signal and Information Processing

Remote Sensing Monitoring and Simulation of City Development for Hainan Province

WANG Heng, ZHANG Li, BI Sen, HAN Rui-dan

2018, 36(5):  798-807.  doi:10.3969/j.issn.0255-8297.2018.05.007

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For two different types of cities of Hainan Province, the urban expansion of Haikou City and Sanya City during 2000-2015 was analysed and monitored by the combination of the pixel unmixing model and decision tree method. Furthermore, we simulated the distribution pattern of the urban land usage in 2020 based on CLUE-S model, and compared the differences of urban development between the two cities. Simulation results show that Haikou City and Sanya City will have substantial expansions in 15 years, especialy Sanya City will be expended 3.4 times. Experiments show that the combination of the pixels unmixing model and CLUE-S model can provide more detail information on the urban development process, and is helpful to urban planning and land resources decisionmaking.

MRI-Based Segmentation and Three-Dimensional Reconstruction of Brain Tumor

HOU Dong-ao, LU Yu-ming, WANG Yu-ling, LIU Wu

2018, 36(5):  808-818.  doi:10.3969/j.issn.0255-8297.2018.05.008

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Analysis on the accurate segmentation and 3D reconstruction of brain tumors are important for the diagnosis of brain tumor diseases. This paper presents an automatic segmentation method for brain tumors. According to the symmetry of human brain structure information, a rough segmentation of brain tumor can firstly be realized by region growing method, and then taken as the initial level set contour for the further accurate segmentation by means of geodesic active contour (GAC) model. Experimental analysis shows that the model has good weak-edge ability on segmenting uneven gray scale. Finally, surface rendering, reconstruction and visualization of the segmented brain tumor sequence images are carried out to provide more dimensional information for brain tumor research.

Asymmetric Distortion Function for Spatial Adaptive Steganography

WANG Zi-chi, ZHANG Xin-peng, QIN Chuan

2018, 36(5):  819-825.  doi:10.3969/j.issn.0255-8297.2018.05.009

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This paper proposes a general method to distinguish the embedding cost for different polarity of embedding change for spatial images. Firstly, at the cost of distortion of pixel grayscale value, the original distortion function is improved. Then the improved distortion function is adjusted iteratively according to the modified pixels. The modification directions are gathered together after the original distortion function is optimized using the proposed method. Thus the stego images perform better undetectability. Experiment results show that the security performance of current popular steganographic methods is observably increased after incorporated the proposed method.

Least Square Image Matching Algorithm Considering Elevation Plane and Parallax Constraints

ZHANG Chun-sen, MU Yan, ZHU Shi-huan, GUO Bing-xuan, QIU Zhen-guo

2018, 36(5):  826-836.  doi:10.3969/j.issn.0255-8297.2018.05.010

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Aiming at the problem that the traditional least square image matching algorithm is limited by the image quality and the initial condition, this paper proposes a least square image matching algorithm considering elevation plane and parallax constraints by means of combining the characteristics of the vertical line locus and the multi-slice least square matching algorithm based on collinear constraints. The algorithm is based on elevation plane constraint matching where the parallax constraint is used in searching and matching process. The parallax offset can provide reliable and stable initial condition for the least square matching, realizing precisely matching of images. There experiments are conducted with the vertical line locus method, the multi-slice least square matching algorithm with collinear conditional constraints and with the proposed algorithm, respectively.Experimental results proof that the proposed algorithm has obvious advantages in matching accuracy and subsequent calculation of aerial triangulation, compard with the other two algorithms.

Speech and Emotional Recognition Method Based on Improving Convolutional Neural Networks

ZENG Run-hua, ZHANG Shu-qun

2018, 36(5):  837-844.  doi:10.3969/j.issn.0255-8297.2018.05.011

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In this paper, we studied the algorithm of speech emotion recognition based on convolutional neural networks, and improved the algorithm of updating convolution kernel weight during the training process of traditional convolutional neural networks, resulting that the algorithm of updating the convolution kernel weight was related to the number of iterations. Simultaneously, in order to increase the difference of emotional phonetic features, the data matrix of the Mel-frequency cepstral coefficients (MFCC) obtained by preprocessing the speech signal was transformed, consequently, improved the expressive ability of convolutional neural networks. Experiments showed that the error recognition rate of the improved algorithm of speech emotion recognition was about 7% lower than that of traditional algorithms.

Method of UAV Autonomous Positioning Based on Encoded Sign during Power Inspection

XU Zhong-xiong, SHAO Gui-wei, XIE Yu-xing, WU Liang, JI Zheng

2018, 36(5):  845-858.  doi:10.3969/j.issn.0255-8297.2018.05.012

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In order to achieve the automatic obstacle avoidance of unmanned aerial vehicle (UAV) during substation inspection, this paper proposes a UAV autonomous positioning method by using encoded sign as control point. First, the design and decoding of encoded sign are discussed. Second, the encoded signs in the image are detected by using the SVM+HOG algorithm, and the tracking algorithm is used to track the encoded sign efficiency. At last, according to the location of encoded signs on the pylon and its corresponding coordinates on the image, the location of UAV can be calculated by using the projective relation between the object points and their corresponding image points. Experiments show that the set of SVM+HOG can detect the encode signs in the image at a recall rate of 99%, and the decoding algorithm remains strong robustness in signs blur, deformation and other extreme conditions, with decoding error rate of only 0.05%. The error of UAV positioning is not more than ±0.03 m, and the algorithm runs at a speed of 10 frames per second, fast enough for practical substation inspections.

Control and System

Exponential Synchronization Control of Uncertain Complex Dynamic Networks with Time-Varying Delay

LUO Yi-ping, SHU Li, ZHOU Bi-feng

2018, 36(5):  859-869.  doi:10.3969/j.issn.0255-8297.2018.05.013

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This paper focuses on the exponential synchronization problems of uncertain complex dynamic networks with time-varying delay. Both time-varying delays and network uncertainties of the complex dynamic network model are considered. As the dynamic changes of nodes and the coupling between nodes are nonlinear, under the condition that the uncertainty satisfies the matching condition and that the delay is unknown but bounded, a new criterion of the exponential synchronization is derived by constructing a suitable Lyapunov-Krasovskii function with the linear matrix inequality (LMI) approach. And the appropriate feedback controllers are designed. Finally, numerical simulation validates the effectiveness of the proposed method.

Nonlinear Neural Network Predictive Control Based on Tree and Seed Algorithm

JIANG Xue-ying, SHI Hui-yuan, SU Cheng-li, LI Ping

2018, 36(5):  870-878.  doi:10.3969/j.issn.0255-8297.2018.05.014

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Because present nonlinear predictive control methods are difficult to solve the nonlinear equation online, a nonlinear neural network predictive control scheme based on tree and seed algorithm(TSA)is proposed in this paper. In this scheme, a process model of the nonlinear system is firstly built up based on radical basis function(RBF)neural networks, and regarded as a predictive model to approximate the process performance of system. Then the predictive output is derived by this model and the quadratic performance index under constrains is designed. And the optimal control law of the nonlinear predictive control system can be online searched with TSA under the performance index. Thus, the proposed scheme can avoid the direct derivation of the control law in complex nonlinear optimization problems and reduce the computational burden. Simulation results of biochemical fermentation process show that the proposed control scheme performs excellent tracking and anti-disturbance abilities.