Table of Content

25 December 2020, Volume 48 Issue 12

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Power & Electrical Engineering

Analysis and Primary-Side Control of Wireless Power Transfer System Based on Series-None Compensation



YANG Jinming, DENG Ziying, LIU Runpeng, et al

2020, 48(12):  1-9.  doi:10.12141/j.issn.1000-565X.190803

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The wireless power transfer system based on SN ( Series-None compensation) has the advantages of high efficiency in the case of strong coupling and high quality factor as well as simple-structured receiver． In order to deal with the unstable voltage caused by mutual inductance shifting and load fluctuation，a primary side detection method was proposed． The actual mutual inductance and output voltage of the receiving side were calculated by measuring the input voltage and current of the transmitting side and the phase difference between them． The closedloop control was realized on this basis． In this paper，the principle of the primary side detection of the system based on Series-None compensation topology and the efficiency characteristics of the system were analyzed firstly． Then the theoretical analysis was verified by the simulations of open loop and closed loop respectively with Simulink simulation software． Finally，the feasibility of the control method was verified by experiments． Simulation and experimental analysis proves that the control method proposed in the article is correct and effective．

Temperature Field Distribution and Ampacity Calculation of Double-Channel Four-Circuit Cables Based on Multi-Field Coupling of Electromagnetic-Thermal-Fluid



LIU Gang, XU Zhifeng, WANG Pengyu, et al

2020, 48(12):  10-17.  doi:10.12141/j.issn.1000-565X.200194

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The laying of multi-circuit cables with double-channel cable trench is a special installation，and there is a lack of relative researches on the influencing factors of the ampacity of such cables． In this paper，a finite element simulation model based on electromagnetic-thermal-fluid coupling was established to analyze the heat dissipation characteristics and influencing factors of the cables installed in double-channel trench，and a corresponding improved laying scheme was proposed． The results show that，under the same load，the temperature of the two circuits near the middle trench wall is more higher，and this is the bottleneck of the ampacity． The decrease in the width of the cable trench makes the temperature of the cable conductor rise linearly，and the temperature rise of the cable circuits near the middle trench wall is greater． The backfilled sand will strengthen the thermal influence of cables in double-channel，leading to a severe reduction on ampacity． And in that case，the thickness of the middle trench wall will have a great impact on the ampacity of the cables． The improved scheme proposed in this paper can significantly improve the ampacity of double-chanel cables when the backfilled sand has poor dissipation performance．

Simplified Predictive Torque Control for Induction Motor with Sliding Mode Speed-Sensorless



YIN Huajie, GUO Zhiyu, ZENG Jun

2020, 48(12):  18-26.  doi:10.12141/j.issn.1000-565X.200137

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A novel simplified predictive control method was proposed for the torque and flux control of induction motor． By introducing a new torque calculation scheme and a multi-step and multi-objective model predictive control strategy，the cost function of torque and flux amplitude was separated． Compared with the traditional model predictive control method，the new method not only reduces the calculation burden but also avoids the influence of weight factor． At the same time，the actual speed in the prediction model was replaced by the observed speed by introducing the sliding mode speed observer，which realizes the speed-sensorless control and avoids many inconveniences brought by the speed sensor． Based on Matlab / Simulink，the simulation results for the speed，torque and current of the motor with the proposed observer and control method were obtained and compared with the traditional field oriented control and direct torque control． The simulation results and the comparison results both verified the effectiveness of the control method．

Thermodynamic and Economic Analysis of Solar Hybrid Cooling Systems for Cold Storages



LI Zeyu, XU Yongrui, CHEN Hongkai

2020, 48(12):  27-33，81.  doi:10.12141/j.issn.1000-565X.200249

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: Ｒecently，the demand for cold storages has increased significantly with the development of society and people＇s living standards． The energy consumption of cooling system occupies 70% of total energy consumption of a cold storage，so to reduce the energy consumption of the cooling system is conducive to the sustainable development of cold storages． Focusing on the poor economic performance of solar cooling system in previous studies，this study put forward the solar absorption-subcooled compression hybrid cooling system ( SASCHCS) ． The absorption subsystem driven by low grade solar energy is used to subcool the compression subsystem，so as to improve the energy-saving and economic performance． The corresponding techno-economic analysis was performed based on quasi-static simulation taking into account the annual meteorological data and cooling load of Guangzhou． It shows that the annual electricity saving for each unit collector area is 63 kW·h and the payback period is only 6. 74 years． Thus，the energy saving and economic performance of SASCHCS is remarkable for the cold storages.

Electronics, Communication & Automation Technology

Reconfigurable Antenna with Wideband Multi-Polarization Based on Coplanar Waveguide Fed



JIN Guiping, LI Long, SUN Yi, et al

2020, 48(12):  34-42.  doi:10.12141/j.issn.1000-565X.200110

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To adapt to the more and more complex communication environment and improve the capacity and quality of communication system，a reconfigurable antenna with wideband multi-polarization based on CPW-fed ( CPW: Coplanar Waveguide) was put forward． The antenna is based on coplanar microstrip lines． Four PIN diodes are placed on the slot etched on the ground plane． By controlling the on-off state of the PIN diode switch，the surface current distribution of the antenna is reconfigured，and the polarization mode of the antenna is changed． With the help of the optimized impedance matching and parasitic elements，the proposed reconfigurable antenna with wideband multi-polarization was designed，including LP ( linear polarization) ，LHCP ( left-hand circular polarization) and ＲHCP ( right-hand circular polarization) ． The measured results show that，the overlapped impedance bandwidth of the proposed antenna in the three polarization modes can reach 48. 5% ( Antenna return loss | S11 | ＜ － 10 dB， frequency range: 2. 42 ～ 3. 97 GHz) ． Under the circular polarization mode，the overlapped axial ratio bandwidth is about 48. 2% ( axial ratio ＜ 3 dB，frequency range: 2. 33 ～ 3. 81 GHz) ． The measured results of this antenna are in good agreement with the simulated ones． Owing to its advantage of wideband and multi-polarization modes，this antenna can meet the requirements of multi-polarization applications in mobile communication and satellite communication.

Tracking Control for a Class of Nonaffine Nonlinear Systems with High-Order Mismatched Disturbances



YANG Hao, PEI Hailong

2020, 48(12):  43-51.  doi:10.12141/j.issn.1000-565X.190845

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Finite time disturbance observer ( FTDO) is a nonlinear disturbance observer which has been widely applied to controller designing for nonlinear systems with high-order disturbances． However，in the previous research， FTDO can only be applied to affined nonlinear systems and used to track a desired set-point． In this paper，a FTDO based nonlinear dynamic inversion approach was developed for the tracking control problem of a class of nonaffine pure-feedback nonlinear systems with high-order mismatched disturbances． A fast subsystem was established through the approximate dynamic inversion scheme． In the slow time-scale，the nonaffine system containing outputs of FTOD was transformed into a linear system with affined form to track the time-varying reference trajectory． The effectiveness of the proposed algorithm is independent to the time-scale split character of the original system，and avoids the problem of“explosion of complexity”in backstepping strategy． The simulation results on Matlab / Simulink environment demonstrate that the controller designed in this paper can accurately estimate high-order disturbances in the case of controlled system with nonaffine structure，and the tracking performance is good．

Monocular Image Depth Estimation Based on Multi-Scale Attention Oriented Network



LIU Jieping, WEN Junwen, LIANG Yaling

2020, 48(12):  52-62.  doi:10.12141/j.issn.1000-565X.200083

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Aiming at the problems of low spatial resolution and unclear edges in the existing depth estimation algorithms of monocular images based on deep learning，a depth estimation algorithm of monocular images based on multi-scale attention-oriented network was put forward． Firstly，an end-to-end encoder-decoder model was designed，and the encoder extracts features at multiple scales． To ensure better depth continuity，the decoder gradually optimize details and scene structure of extracted multi-scale features by combining residual learning with channel attention fusion． Considering the loss of depth details caused by multiple down-sampling，a boundary enhancement module was designed． By introducing spatial attention，the inter-class contrast of different objects was improved to enhance the boundary details of the image． Finally，the optimization module fuses multi-scale features from the decoder and the boundary enhancement module to generate a depth image． Experimental results show that，compared with the current mainstream algorithms，the depth image generated by the algorithm has improved quality，showing more detailed object contour information and good performance in both objective indicators and subjective effects．

A Circuit Edit Method for ICs of Flip-Chip /Multilayer Interconnected Structure



LIN Xiaoling, ZHANG Xiaowen, GAO Rui

2020, 48(12):  63-71.  doi:10.12141/j.issn.1000-565X.200118

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Flip-Chip packaging is an important packaging form for high-performance devices． Its unique packaging form brings new challenges to circuit-edit ( CE) ． A CE method for ICs of flip-chip /multilayer interconnected structure was proposed in this paper by combining the techniques of thinning the back of the chip，deep and wide trench etching technology based on Focused Ion Beam ( FIB) ，trench etching endpoint monitoring based on dynamic grating diffraction fringes，and FIB circuit modification． Firstly，this method uses a global polishing thinning method to reduce the thickness of the flip-chip to about 70 μm． Then uses deep and wide trench etching technique and dynamic grating diffraction fringe-based trench etching endpoint monitoring technique to perform deep and wide Si trench etching． The chip is further thinned to about 4 μm，and then the circuit is edited with a FIB CE technique． The successful CE results of the M1 metal open circuit in a 6-layer metal CMOS chip show that the proposed method can effectively accomplish the modification of open or short circuit in flip-chip /multilayer interconnected structured ICs．

Architecture & Civil Engineering

Simulation Analysis on Motion Characteristics of Fire Smoke in Audience Hall of Theaters



ZHANG Honghu, DENG Xirui, LIU Bin, et al

2020, 48(12):  72-81.  doi:10.12141/j.issn.1000-565X.200025

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A typical fire scenario in Hangzhou Dongpo grand theatre was simulated with the CFD ( computational fluid dynamics) technique，in order to improve the understanding on the fire behavior in the theater audience hall and provide technical references for mechanical smoke exhaust design． The study analyzed the effect of the development of the smoke，the effect of the smoke concentration and temperature distribution on the audience evacuation， and obtained the data about the performances of the smoke exhaust with different methods． The study shows that smoke flow inside the hall develops with a process of “lift up-ceiling jet-sink down”，affected by mechanical exhaust methods． Compared with the exhaust outlets set on the center of the ceiling，the exhaust outlets set on the side walls show a better smoke exhaust performance due to their higher adaptability to variety of fire source locations． When the fire sources are under the auditorium balcony，smoke cannot be effectively discharged by the common smoke exhaust system． For the same smoke exhaust velocity and smoke outlet volume，there is an optimal combination of the single outlet area and the number of the outlets to reach the highest smoke discharge efficiency．

Experimental Study on Mechanical Behavior of UHPC Joint of Precast Bridge Deck



SHI Xuefei, GAO Yi, CAO Shenghui

2020, 48(12):  82-90,124.  doi:10.12141/j.issn.1000-565X.190742

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Simplifying the joint structure of precast beams so as to facilitate industrial construction has become a hot spot in the research of precast and assembled bridges． Using ultra-high performance concrete ( UHPC) can greatly simplify the joint structure and provide a new solution for rapid construction． In this paper，experimental research on bridge deck joints was carried out． Pull-out tests were designed to simulate the interaction of UHPC and common steel bars in bridge deck． Bending tests on plate joint specimens based on actual engineering projects were also conducted． Based on finite element numerical simulation and theoretical stress analysis，the influence and effecting mechanism of factors，such as embedded length of steel bars，thickness of protective layer，transverse spacing of steel bars，diameter of steel bars ( d) and interface form，on the mechanical properties of UHPC joints were studied． Finally，the recommended values of parameters for UHPC joint design of bridge deck were given． That is， rough diamond interface should be used and the thickness of protective layer should be no less than 2d and the embedding length should be no less than 8d．

Research Progress of Long-Term Time-Dependent Deformation of Geopolymer Concrete



YANG Shiyu, ZHAO Renda, ZENG Xianshuai, et al

2020, 48(12):  91-104.  doi:10.12141/j.issn.1000-565X.190836

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Geopolymer，with merits of high early strength，good thermostable performance and less environmental pollution，is a new inorganic cementing material involving intensive research both at home and abroad． It is very important to grasp the shrinkage and creep characteristics of geopolymer to determine whether it can be used to replace Portland Cement ( OPC) or not． The research of geopolymer on shrinkage and creep in recent years were reviewed in this paper focusing on the shrinkage and creep characteristics，mechanism and improvement measures of fly ash based geopolymer ( AAFA) and slag based geopolymer ( AAS) ． The results show that: AAFA has a larger shrinkage rate at room temperature，and AAFA cured at high temperature can obtain a smaller shrinkage rate than OPC; AAS shrinkage rate is much larger than OPC; the shrinkage mechanism of geopolymer is not exactly the same as that of OPC; the shrinkage of geopolymer can be reduced to a certain extent through properly raising the curing temperature，reducing the sodium content and adding fibers; the geopolymer concrete prepared with fly ash and appropriate amount of slag is a promising building material that can meet the requirements of strength and obtain a smaller dry shrinkage than OPC concrete; AAFA concrete has a smaller creep than OPC concrete，but AAS concrete has a larger creep than OPC concrete． In addition，the addition of a small amount of slag to AAFA has little effect on creep． The nano-indentation technology can be used to quickly and reliably evaluate the creep of geopolymer concrete． Finally，some suggestions for further research were put forward．

Artificial Intelligence Special

Drift Compensation for Electronic Nose Based on Sample Distribution Weighting Cross Domain Extreme Learning Machine



YAN Jia, CHEN Feiyue, YI Ruonan, et al

2020, 48(12):  105-113.  doi:10.12141/j.issn.1000-565X.200316

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To solve the problem of low classification accuracy of electronic nose ( E-nose) caused by sensor drift in various applications，a sample distribution weighting cross domain extreme learning machine model was proposed． Considering the different contributions of a single sample to the global distribution discrepancy measure，it uses the maximum mean discrepancy based on the sample distribution weighting as a measure of the sample distribution discrepancy between domains． The data of source domain and target domain were projected onto a high-dimensional extreme learning machine feature space． Then a suitable projection direction was found，by which the data was projected onto a common subspace． Thus the source domain and target domain data in the subspace had a similar distribution． Matlab was used to simulate this algorithm，and the effects of different number of hidden layer nodes on the recognition rate of the algorithm were compared so as to verify the feasibility of the algorithm． The results show that the model proposed in this paper can significantly reduce the distribution discrepancies between the two domains，and can meet the distribution requirements of traditional classification algorithms for training and test data，thus to improve the classification accuracy of E-nose．

W-Net-Based Segmentation for Ｒemote Sensing Satellite Image of High Resolution



FAN Zizhu, WANG Song, ZHANG Hong, et al

2020, 48(12):  114-124.  doi:10.12141/j.issn.1000-565X.200365

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Remote sensing satellite image，which can provide accurate location information because of instantaneity and objectivity，has been widely used in agricultural production，environmental protection and other fields． In order to solve the difficulties in recognizing the mass remote sensing satellite images，the image segmentation method based on convolutional neural networks was used to extract the typical land spectral information and spatial information in the remote sensing image and to identify the remote sensing satellite image． Firstly，the experimental data was generated by clipping remote sensing ima-ge data and annotating data． The categories in the data were counted and oversampling was used to deal with the problem of data imbalance． Then，a new image segmentation network named W-NET was proposed to train the data by adding a top-down feature pyramid structure to the U-Net framework combining with global context module． Finally，large-scale remote sensing satellite images were recognized by image overlap strategy． Compared with three popular semantic segmentation networks and two special networks for remote sensing satellite image segmentation，our method achieves 74. 7% mean IoU and 95. 1% accuracy in 2017 AI classification and recognition contest of CCF satellite images，and achieves 69. 6% precision and 79. 9% recall in Massachusetts building segmentation task． W-Net has the highest accuracy and mean IoU among the six networks． Experimental results show that the feature pyramid structure and global context module can improve the segmentation accuracy of the semantic segmentation network，and this method is feasible for remote sensing satellite image segmentation．

Approach for Spammer Detection in Weibo Based on Multi-View Fusion



YANG Xiaohui, LIANG Xiao

2020, 48(12):  125-134.  doi:10.12141/j.issn.1000-565X.200366

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In order to detect spammers more effectively in Weibo，an approach based on multi-view fusion was proposed． First，a user representation strategy for integrating multi-view information was designed to characterize users from 3 views，namely，user behavior，social relationship and text content． In view of the deficiencies that the existing approaches do not fully consider the user＇s fans and user＇s environment in social networks，new features such as fan ratio，fan average bidirectional connection rate，community-based bidirectional connection rate，communitybased cluster coefficient，etc． were introduced． Then，a multi-view fusion decision model based on a linear weighting function was constructed． A linear weighting fusion was carried out based on the classification results from each view． The optimal fusion coefficient was obtained by minimizing the approximate error，and then the final classification result was obtained． The test result on the real data from Weibo show that this approach can not only effectively detect spammers，with significant improvement in precision and F1-sorce，but also exhibits greater stability especially when processing unbalanced data． It also analyzes the impact of different views on the final detection effect， and the results show that the user＇s social relationship view has the most significant effect.

Marine Mineral Classification Based on Single-Output Chebyshev-Polynomial Neural Network



JIN Long, CHEN Xiufang, CHEN Liangming, et al

2020, 48(12):  135-143.  doi:10.12141/j.issn.1000-565X.200389

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Aiming at the classification of marine minerals，an improved single-output Chebyshev-polynomial neural network with general solution ( SOCPNN-G) was proposed． This model uses the general solution of pseudo-inverse to find the parameters and expand the solution space，and it can obtain weights with better generalization performances． In addition，in this model，the subset method was used to determine the initial number of neurons and obtain the optimal number of the cross validation． Finally，the modified SOCPNN-G was tested in the marine mineral data set． The experimental results show that the training accuracy and test accuracy of the model can reach 90. 96% and 83. 33% ，respectively，and the requirements for computing performance are low． These advantages indicate that this model has excellent application prospects in marine minerals．

Attribute Reduction in Multi-Source Fuzzy Information System



LI Mengmeng, PANG Jinzhong, CHEN Minghao

2020, 48(12):  144-152.  doi:10.12141/j.issn.1000-565X.200386

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People get a lot of fuzzy information from multiple channels，so it is very important to fuse the obtained information to get more accurate information． In this paper，a fusion model of multi-source fuzzy information system was constructed by using conditional entropy． The new conditional entropy was used to fuse multiple fuzzy information systems into a fuzzy information table． Then，the similarity between two fuzzy relations was constructed by using the paste progress between any two fuzzy sets，and three kinds of fuzzy relation similarity were established． In addition，based on the fused fuzzy information table of multi-source fuzzy information system，the attribute reduction of the fused fuzzy information table was carried out according to three kinds of fuzzy relation similarity，and then the attribute reduction of multi-source fuzzy information system was realized． Finally，the correctness and effectiveness of the proposed model was verified by experiments． The results show that the reduction method of multi-source fuzzy information system proposed in this paper has a certain value in dealing with fuzzy data and enriches the theoretical basis of knowledge discovery．