Table of Content

25 February 2019, Volume 47 Issue 2

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2019, 47(2):  0. 

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Electronics, Communication & Automation Technology

Kinematics Modeling of Snakelike Robot Based on Screw Theory

 



WEI Wu LI Yanjie LIAO Zhipeng ZHANG Jing

2019, 47(2):  1-8.  doi:10.12141/j.issn.1000-565X.180061

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 In view of the traditional D-H parameter method has many disadvantages，such as the local coordinate system needs to be established on every joint， the modeling process is complex， the geometric meaning is not clear and the inverse solution leads to the rooting problem， the kinematics modeling of snakelike robot which has many joints and high structural redundancy was studied，and the method of the snakelike robot’s position modeling based on screw theory was proposed． Meanwhile，the equivalence between the D-H parameter method and the screw theory modeling method were proved，and the velocity Jacobi matrices of snakelike robot were solved by using the exponential product formula based on screw theory，establishing the speed model of the snakelike robot． The motion simulation of the snakelike robot was carried out by using Adams software． The measured linear velocity and angular velocity curves of the end effecter are consistent with the linear velocity and angular velocity curves of the end effecter calculated by Matlab． The results show that screw theory modeling method is correct， simple and effective． 

Design of Two-point Modulation Phaselocked Loop for Polar Transmitter

 



LIANG Zhen LI Bin HUANG Mo XU Ken YE Hui

2019, 47(2):  9-15.  doi:10.12141/j.issn.1000-565X.180218

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Two-point modulation phaselocked loop ( PLL) for Bluetooth polar transmitter was studied and designed by using 0. 11μm 1P6M CMOS process． In order to correct the loop gain of two phase modulation paths in the PLL and reduce the frequency shift keying error of using the phaselocked loop，a new gain correction method was proposed． And a new phaselocked loop circuit of two-point modulation based on gain calibration was proposed to reduce phase noise of PLL and accelerate the locking time of phaselocked loop． Chip measured results show that when voltage controlled oscillator oscillates at 4. 8 GHz，the phase noises at 10 kHz，1 MHz，3 MHz offsets are －83dBc/Hz， －108dBc/Hz and －114dBc/Hz，respectively． When using the polar transmitter of phaselocked loop to transmit the 0dBm signal，the FSK error is 2. 97%，and the phaselocked loop occupies 0. 32 mm2． The overall performance meets the requirements of Bluetooth ＲF chip test specification． 

Electronics, Communication & Automation Technology

Broadband Low Noise Amplifier Architecture Based on Coupling and Negative Feedback

 



YAO Ruohe HE Xiaomeng

2019, 47(2):  16-23.  doi:10.12141/j.issn.1000-565X.180254

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In order to improve the performance of existing broadband LNA topology cirtuits，a broadband low noise amplifier architecture combining cross-coupling and negative feedback technology is proposed，which further introduces a new negative feedback structure by adding PMOS transistors that are cross-connected from the output to the input based on a composite NMOS/PMOS cross-coupled inductorless broadband differential shunt feedback commonsource low-noise amplifier ( SFCS-LNA) ． By adjusting the transconductance of the adding PMOS transistors to composite NMOS/PMOS cross-coupled SFCS-LNA， the degree of freedom of the LNA was increased，and the problem that the feedback resistance of the original composite NMOS/PMOS cross-coupled SFCS-LNA is limited by the input matching was solved，which could independently increase the resistance of the feedback resistor while the input matching is maintained，minimizing the contradictions of mutual restraints between noise， input matching and gain of the LNA． The results show that the LNA architecture can effectively reduce the noise figure and improve the voltage gain of the LNA． 

Nongrid Sparse Array Technology for Portable 3D Imaging Sonar

 



ZHAO Dongdong LIU Xuesong ZHOU Fan CHEN Yaowu

2019, 47(2):  24-30.  doi:10.12141/j.issn.1000-565X.180315

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A nongrid sparse array optimization method was proposed to reduce the hardware cost of the portable 3D imaging sonar system and guarantee the performance of beam pattern of the array． Based on the cross array， the element position perturbation was introduced into the simulation annealing ( SA) algorithm to achieve the nongrid sparse optimization for the cross array and decrease the element number． Based on multiplefrequency transmitting beamforming and parallel subarray receiving beamforming algorithms，a new energy function for the SA algorithm was defined to make the sparse cross array has a realtime imaging property and lower computational requirement． Finally， the proposed method was employed to optimize a cross array with 100 +100 elements． The experiment results demonstrate that the nongrid sparse array obtained by the proposed method can achieve the presupposed beam pattern performance and own realtime imaging property and low computational requirements． Compared with the existing literature， the sparse array has the fewest active elements while maintaining the same beam pattern performances． 

Distributed Sampled-data Control of Cyber-physical Systems

 



HUANG Junhua XU Bugong CHEN Liding

2019, 47(2):  31-40.  doi:10.12141/j.issn.1000-565X.180163

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 A new distributed sampled-data control scheme was proposed for the problem of cooperative sampled-data control for cyber-physical systems ( CPS) ． Firstly，the physical process and data information processing in CPS were modeled as a set of coupled and correlated subsystems and a set of controllers that can communicate with each other． Then the Lyapunov-Krasovskii functional was constructed by virtue of the input delay method，and the stability of the system was studied． Based on the theory of stability，sufficient condition on the sampled-data control of the CPS was derived，and a distributed sampling control algorithm was designed on this basis． Numerical simulation results show that: when the communication connection of the controller is equivalent to the coupling degree of the system，the gain of the subsystem controller with strong coupling degree is small; when the maximum sampling time increases，the control constraint quantity of the controller increases． The proposed algorithm can reasonably allocate controller resources in CPS according to the coupling relation of physical processes．

Segmentation of the Partial Ground Glass Opacity Pulmonary Nodules with Wavelet Energy Guided Active Contour Model

 



FENG Bao CHEN Xiangmeng LI Pusheng CHEN Yehang YAO Nan LONG Wansheng

2019, 47(2):  41-49,58.  doi:10.12141/j.issn.1000-565X.180259

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Due to the intensity inhomogeneity and fuzzy boundary of the solid components in partial ground glass opacity ( pGGO) pulmonary nodules，it is difficult to obtain accurate segmentation results through the traditional active contour model． Thus an improved wavelet-energy guided active contour model was proposed for solid component segmentation in pGGO． First，the grayscale information of the image was converted into wavelet coefficients by wavelet transform． The low-pass coefficients were fuzzified to suppress over-enhancement and under-enhancement regions． By integrating high-pass wavelet coefficients and the fuzzified low-pass coefficients，wavelet energy was calculated to build the region term of the active contour model to enhance the dissimilarity between solid part and surrounding ground glass part． Then， the Gaussian mixture model was used to calculate the posterior probability of the pulmonary nodule image． When the posterior probability difference is selected as the boundary detection function， the boundary detection function tended to zero at the boundary of the solid component in pGGO，and the proposed active contour curve stopped evolution． The experimental results show that the model proposed in this paper has a true positive rate of 0. 95，a false positive rate of 0. 23 and a similarity of 0. 80，which contributes to the determination of the solid components in pGGO． 

Image Matching Algorithm Based on Directed Hypergraph

 



ZHU Ming ZHANG Jian LIANG Dong TANG Jun ZHANG Yan

2019, 47(2):  50-58.  doi:10.12141/j.issn.1000-565X.180278

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An algorithm for images matching based on directed hypergraph was proposed to improve the matching accuracy of graph model under the complex transformation． Firstly，3-uniform hypergraphs in the two feature points set to be matched was constructed by the algorithm，and the weights of the triples contained in each hyperedge was calculated， then these weights were used to construct weighted adjacency tensors． Finally，image matching was achieved by convex-concave relaxation algorithm． The experiments with both simulate and real results show that the proposed algorithm can achieve higher matching accuracy and good matching effect for complex transformed images． 

Computer Science & Technology

Compressed Video Background/Foreground Recovery and Separation Based on PTV-TV Tensor Modeling

 



HAN Le WEI Wei GAO Li

2019, 47(2):  59-67.  doi:10.12141/j.issn.1000-565X.180354

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The H-TenＲPCA model is an effective method which directly processes raw multidimensional data without destroying 3D tensor structure． However，the model demands long computing time and high requirements for hardware． What’s more，the algorithm for H-TenＲPCA has no convergence guarantee in theory． Motivated by this，background and foreground before compression were reconstructed by using PTV of background video and continuity of foreground spacetime ( 3D-TV) ，and a compressed video background and foreground restoration and separation model based on PTV-TV tensor modeling was proposed，and two ADMM algorithms with guaranteed convergence were used to solve the related optimization problems． Extensive empirical studies on open data sets show that the PTV-TV model can recover the background and the foreground，and the computing time of this model is only about 2/3 of that of H-TenＲPCA． For complex dynamic background data，the PTV-TV model maintains the same peak signalto-noise ratio and image structure similarity as H-TenＲPCA model under significant time advantages．

Method of Extraction Regions of Interest for Robust Vehicle Thermal Imaging Pedestrian Detection

 



XU Zhewei XU Ｒuilin LIU Qiong

2019, 47(2):  68-76,2.  doi:10.12141/j.issn.1000-565X.180233

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Current methods of extracting regions of interest are difficult to balance the high recall rate and the number of ＲoIs． To reduce the amount of computation and ＲoI，and increase recall rate，a ＲoIs extraction method suitable for robust vehicle thermal imaging pedestrian detection was proposed． First，the vertical edges of possible pedestrians in the image were judged according to the directional differences of pedestrian edge features，and their amplitude was enhanced． Then，the boundary boxes generated by sliding windows were filtered by cascade human dimension constraint and adaptive local double threshold segmentation method，and a large number of non-human boundary boxes were removed． Next，according to the outline characteristics of pedestrian，the filtered bounding boxes’score were evaluated by using a T-shaped template，and the unrelated edges inside the bounding boxes were removed while preserving possible pedestrians’leg information． Finally，the ＲoIs were reordered with the strong size constraint of pedestrians，so that the recall rate could be improved when a fixed amount of ＲoI was extracted． A contrast experiment was conducted on a thermal imaging pedestrian detection dataset called SCUT DataSet． The results show that when 400 ＲoIs are extracted from each image，the recall rate of our method reaches 92%; compared with the EdgeBox method，the recall rate increases by 21%，and the calculation time decreases by 10%．

Adaptive Dual Fractional-order Optical Flow Model for Motion Segmentation

 



ZHU Bin TIAN Lianfang DU Qiliang YU Lubin

2019, 47(2):  77-84.  doi:10.12141/j.issn.1000-565X.180295

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An adaptive dual fractional order variational optical flow ( ADFOVOF) model was proposed to solve the problem that the current optical flow algorithm cannot segment moving objects in weak texture region under insufficient illumination． The model was an adaption version of dual fractional order optical flow ( DFOVOF) model that adopts fractional differential mask in both，the data term and smoothness term of traditional Horn ＆ Schunck ( HS) model． Specially，the order and size of fractional order differential mask for each region were adjusted by image signal to noise ratio ( SNＲ) whereas，the shape of the fractional order differential mask was regulated by super-pixel that prevents the mask to interfere by surrounding regions． The experiment results show that our algorithm can get accurate optical flow field and obtain clear motion outlines under insufficient illumination or illumination changes scenes． 

Formal Semantics of Operators of Normal Function Tables in Tabular Expressions

 



2019, 47(2):  85-91.  doi:10.12141/j.issn.1000-565X.180335

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As one of typical Tabular expressions，normal function table is widely used in software documents． Semantics of operators of normal function tables was studied． Firstly，the formal grammar of normal function tables was proposed． Then，regularity，completeness and disjointness were discussed and the evaluation process was explained． Next，according to the influence range of operators， the semantics of composite operator， replace operator， extract operator and expand operator were described respectively with internal operators and external operators as classification criteria，and the closure of each operator was discussed． Finally，an elevator control system example was given to illustrate the rationality and availability of formal semantics of normal function table operators． The result of the example shows that the semantic description of normal function table operators presented in this paper is consistent with the actual result． 

Colocation Privacy Protection Method in Mobile Social Networks

 



LI Jiachun XIONG Dongqing CAO Jianzhou

2019, 47(2):  92-97,105.  doi:10.12141/j.issn.1000-565X.180316

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 Information with location tags and friends labels shared by users in location-based mobile social networks，can reveal not only the user’s location but also the friend’s location，and thus lead to the location privacy loss problem based on the colocation information attack． In order to prevent the colocation privacy attack，a location privacy protection method was proposed． A relation strength calculation algorithm based on the online interaction between users and friends was designed，a mapping and quantitative method for the location privacy protection requirement was put forward，and an algorithm based on colocation information concealment and time adjustment called CCTA was explored． Experimental results on the twitter data set indicate that the proposed method has better performance and could be suitable for colocation privacy protection． 

Improved DPC Clustering Algorithm with Neighbor Density Distribution Optimized Sample Assignment

 



JI Xia ZHANG Tao ZHU Jianlei LIU Shicheng LI Xuejun

2019, 47(2):  98-105.  doi:10.12141/j.issn.1000-565X.170550

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DPC algorithm is a new density based clustering algorithm that can automatically determine the number of clusters and cluster centers． However， there is a defect in the stability of clustering quality in the sample allocation strategy． KNN-DPC，an improved algorithm of DPC，has better clustering effect，but its practicality is affected by the low efficiency． In order to overcome the deficiencies of DPC algorithm and KNN-DPC algorithm，a neighbor density distribution optimized DPC clustering algorithm was proposed． Firstly， the algorithm searched and found the cluster centers with DPC algorithm． Then， two sample allocation strategies were adopted based on the neighbor density distribution of the sample，which was in turn used to assign the rest samples to the corresponding cluster． Theoretical analysis and the thorough experiments on several popular test cases include synthetic datasets and real-world datasets from UCI machine learning repository show that the clustering algorithm proposed can quickly determine the cluster center of arbitrary shape data and effectively perform sample cluster allocation． Compared with DPC algorithm and KNN-DPC algorithm， the proposed algorithm has a better balance between clustering effect and time performance，and has high stability． The algorithm proposed is an effective adaptive clustering algorithm that can be applied to largescale data sets． 

Traffic & Transportation Engineering

Comprehensive Evaluation Method of Road Driving Comfort Based on D-S Evidence Method

 



ZHANG Jinxi ZHOU Tongju WANG Lin WU Yang

2019, 47(2):  106-112.  doi:10.12141/j.issn.1000-565X.180307

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 Ｒoad driving comfort is mainly affected by the pavement roughness． At present， there are three evaluation methods: subjective feeling，driving vibration and heart physiological changes of drivers and passengers． Due to different test objects，test methods and evaluation criteria，the accuracies of different methods for road driving comfort evaluation are different，and the evaluation results are also different． In order to improve the accuracy and objectivity of road driving comfort evaluation，a comprehensive evaluation method for road driving comfort using D-S ( Dempster-Shafer) evidence method for decision-making fusion of three evaluation methods was proposed to test the outdoor riding test results of 12 asphalt pavements with roughness changing from 1. 06 ～5. 53m/km． The research results show that the comprehensive evaluation system of driving comfort based on road roughness established by D-S evidence method can significantly reduce the uncertainty of each evaluation method，verify the validity of the model，and obtain the absolute threshold of road roughness with 3 kinds of comfort evaluation methods; the speed has an important influence on the proportion of uncertainty in the comprehensive evaluation system，which is in line with the actual situation． 

Collision Analysis of Round End Shaped Anti-collision Floating box with Sandwich Structure of Bridge Pier



2019, 47(2):  113-119.  doi:10.12141/j.issn.1000-565X.180455

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To avoid impact and flexible energy dissipation anti-collision design,the curved-shaped anti-collision floating box made of steel-polyurethane sandwich plate is introduced for the round end shaped pier in the river channel. The ship, floating box, and pier collision system simulation model is established by ABAQUS software. Impact on the floating box, the pier, system energy conversion, and the turn the bow degree are analyzed in different angles when the collision. The results show that the floating box has a good anti-collision effect, absorbs most ship kinetic energy, reduces the impact force of pier under the most unfavorable impact. The box removes the bow easily when colliding obliquely in the general case , reserves most of the ship kinetic energy in the flank crash, protects bridge pier effectively.

Spatial Alignment Grey Prediction of Specialshaped Arch Bridge Arch-rib Based on MGM( 1， n) Model



CHEN Deyi YAN Quansheng ZHU Shiyao

2019, 47(2):  120-127.  doi:10.12141/j.issn.1000-565X.180154

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Combining the characteristics of grey prediction model and spatial alignment control of specialshaped arch bridge arch rib，a MGM( 1， 2) model for spatial alignment grey prediction of the specialshaped arch bridge archrib was established based on the grey system theory，and the model considered the axis deviation and arch rib rotation factors． On the basis of giving the concept and solution method of the MGM( 1， n) model，a corresponding program was compiled by using Matlab software platform． The experimental results based on engineering examples show that the predict results of the specialshaped arch bridge arch rib from MGM( 1， 2) model are in good agreement with the field test values，which demonstrates that the MGM( 1， 2) model for spatial alignment grey prediction of the specialshaped arch bridge arch rib is scientific and reasonable． 

Application of Surface Deformation Method Based on Radial Basis Interpolation in Multi-objective Optimization of Ship Hull

 



FENG Baiwei FENG Mei CHANG Haichao ZHANG Limei

2019, 47(2):  128-136.  doi:10.12141/j.issn.1000-565X.180209

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Accurate and effective hull surface expression and modification techniques play an important role in optimization of ship hull． Taking the DTMB5415 ship as the research object， the ship resistance performance under different Froude numbers ( Fr) was optimized with the surface modification method based on radial basis interpolation and combined with CFD calculation tool and multi-objective particle swarm algorithm． In the optimization results， three typical ship types were selected for analysis． When Fr was 0. 41， the plan 1 was better，and the wave resistance was reduced by 18. 83%． When Fr was 0. 22， the plan 3 was better，and the wave resistance was reduced by 49. 66%; when Fr was 0. 28，the plan 2 was a compromise，and the wave resistance was reduced by 30. 23%． The optimization results show that the surface deformation method based on the radial basis interpolation technique can effectively produce smooth hull profiles． 

Optimization of the Distribution Density of the Shared Bicycle in the Case of Paid Occupancy of Public Space

 



CHEN Kang LI Jiajun WANG Ao YANG Zhongzhen

2019, 47(2):  137-144.  doi:10.12141/j.issn.1000-565X.180190

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The increase of distribution density of shared bicycles raises users’convenience on one hand，while worsens the conditions of public space on the other hand． As in many cities the public spaces are crowded with the shared bicycles and the pedestrians have been greatly affected． In order to optimize the distribution density of the shared bicycles and alleviate the disorderly occupancy of city’s public space，a sample city was surveyed on the users to determine the relationships between the distribution density and users’utility． Then，according to the pedestrian traffic flow characteristics and the evolution theory of crowded accident risk formation， the influence function of the drop density of shared bicycles on the reduction of public space， the comfort and safety of public space utilization was fitted． Finally，an optimization model of the distribution density of the shared bicycles in the case of paid occupancy of the public space was built to determine the distribution density according to the factors such as operators’profit，users’utility，public space occupation cost and the risk of safety accident of the pedestrians． The results of the case study show that by optimizing the density， the maximum number of bikers can be achieved， the pedestrian walking needs can be met，and the incidence of safety accidents can be reduced．