Table of Content

25 February 2020, Volume 48 Issue 2

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Energy, Power & Electrical Engineering

Ｒecognition of Defects in Pins Based on Generative Adversarial Network and ＲetinaNet



WANG Jian, WANG Kai, LIU Gang, et al

2020, 48(2):  1-8.  doi:10.12141/j.issn.1000-565X.190345

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Manually marking the defect of the pin in the aerial survey of the drone is a time-consuming and labor- intensive task． To solve this problem，the deep learning algorithm ＲetinaNet was used to realize the automatic labe- ling of defects in pins． Given that if the unclear data collected by the drone is directly detected，the problem of low recognition accuracy can not be avoided，so a method for intelligent identification of defects based on generative ad- versarial network was proposed． That is to improve the local texture，edge and other details by the mutual game be- tween the generator and the discriminator，so as to improve the quality of such pictures and combine the defect in- telligent recognition algorithm model to extract accurate features to achieve defect detection． Finally，since the fuzzy- clear picture for generating network training is difficult to obtain，a fuzzy-clear picture pair was constructed by com- bining Markov process and sub-pixel interpolation． The experimental results show that the RetinaNet show excellent performance when detecting clear pictures，but for fuzzy picture，it can also lead to detection error．The constructed fuzzy-clear picture pair can effectively train the generated confrontation network to have deblurring function，which is beneficial to the convolutional neural network to extract more abundant features，thereby further improving the recognition rate of blurred pictures．

Partial Discharge Signal Denoising Method Based on S-Transform and Singular Value Decomposition#br#



NIU Haiqing, SONG Tinghan, LUO Xin, et al

2020, 48(2):  9-15.  doi:10.12141/j.issn.1000-565X.190328

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According to the characteristics that white noise follows 2 distribution in the S-transform domain and its average power spectrum is linearly correlated with the frequency，a partial discharge signal denoising method based on S-transform and singular value decomposition was proposed． Firstly，the time-frequency matrix of noisy partial discharge signals was obtained by S-transform． Secondly，the time and number of PD signal were determined by singular value decomposition and singular value difference spectrum theory，and the white noise area was obtained．Then the first denoising of PD signal was carried out by constructing the linear equation in proportion to frequency and dealing with the time-frequency matrix with hard threshold method． Finally，the second denoising of PD signal was done with singular value decomposition theory． Both the simulation and the measured signals show that the denoising effect of the proposed method is better than that of the wavelet threshold method，and the method is simpler and faster．


Random Forests Algorithm-Based Fault Diagnosis for Refrigerant Charge



ZHOU Xuan, WANG Xiaopei, LIANG Liequan, et al

2020, 48(2):  16-24.  doi:10.12141/j.issn.1000-565X.190160

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The refrigerant charge ( ＲC) breakdown of chiller is a high-risk fault that directly affects the operational efficiency of air conditioning system． Due to the mass representative parameters，it is difficult to detect the fault on- line effectively，quickly and accurately． Aiming at these problems，a fault diagnosis method based on random fo- rests ( ＲF) algorithm was proposed for the ＲC breakdown by using the fault database of refrigeration provided by ASHＲAE in 1999． Directly measured feature parameters related to ＲC were analyzed． Under the premise of retai- ning the physical meaning，contribution rate of each fault feature was studied with ＲF algorithm． Then the detection accuracy of ＲC fault diagnosis based on ＲF，support vector machines ( SVM) and decision tree ( DT) algorithms were compared under the condition of different dimensions and sample size． The results show that the ＲF algorithm has the best recognition efficiency and highest classification accuracy． Compared with DT and SVM，the average detection accuracy of ＲF increases by 3. 3% and 2. 9% ，respectively． Furthermore，three important fault charac- teristics which have a high impact on the diagnosis of ＲC were analyzed． This can provide a theoretical basis for en- suring operating performance and safe operation of refrigeration system．

Steam Gasification Characteristics of Rice Straw with Iron-Based Oxygen Carrier



LIAO Yanfen, MO Fei, WU Yuting, et al

2020, 48(2):  25-33,41.  doi:10.12141/j.issn.1000-565X.190080

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Conventional gasification and chemical looping gasification process of rice straw were studied in a fixed bed tubular furnace with argon as gasification medium and steam added． The cyclic characteristics of pure Fe₂O₃ and hematite as oxygen carrier were compared． The results show that the gasification efficiency of conventional gasi- fication or chemical looping gasification without steam was not high． The combination of steam and oxygen carrier has significantly positive effect on the gasification process，and can obviously improve the H₂ gas yield． At the same time，the carbon conversion efficiency and gasification efficiency can reach 80% ． The gas yield，gasification efficiency and carbon conversion efficiency are optimal，under the condition that the temperature is 850 ℃，the speed of steam pump is 1. 2 r/min，and the Fe₂O₃ /C molar ratio is 0. 25． Ｒaising temperature can promote the gas- ification reactions，but it can easily lead to oxygen carrier deactivation． The oxygen carrier is mainly converted into Fe₃O₄ during the gasification process，and the reactivity of oxygen carrier decreases after multiple redox cycles． Compared with the pure Fe₂O₃ oxygen carrier，hematite shows better stability in the process of cyclic gasification．

Thermal Performance of Ｒoll Bond Aluminum Vapor Chamber



LI Yong, XU Peiken, YANG Shifan, et al

2020, 48(2):  34-41.  doi:10.12141/j.issn.1000-565X.190411

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Aiming at the urgent cooling demand of 5G base stations，a kind of Ｒoll bond Aluminum Vapor Chamber (RAVC) ，made from hollow aluminum substrate formed by printing，rolling，inflating，degassing，injecting and sealing processes，was prepared． The thermal performance of RAVC，such as thermal resistance and capacity，un- der different filling ratios and working conditions was investigated． The results indicate that RAVC shows best ther- mal performance under gravity working condition． The thermal conductivity can reach 19900 W/( m·K) when filling ratio is 10% and heating power is 60 W; RAVC reaches the heat transfer limit when filling ratio is 5% and heating power is over 60W; temperature oscillation occurs when filling ratio is over 25% and heating power is under 10W． Under horizontal and anti-gravity working conditions，RAVC's thermal performance becomes worse，and its start-up performance in horizontal state is better than that under anti-gravity working condition，but its thermal performance is not better until it becomes stable．

Numerical Simulation of Droplet Departing Induced by Heterogeneous Surface



LI Peisheng, HUANG Jie, WANG Zhaotai, et al

2020, 48(2):  42-49,75.  doi:10.12141/j.issn.1000-565X.190282

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The relationship between the critical diameter of droplet drop and the wall wettability on the homogene- ous surface，and the drop phenomenon of droplet polymerization on the heterogeneous surface，were studied with the pseudo-potential lattice Boltzmann method ( LBM) multiphase flow model． The influence of droplet size，wall wettability，and droplet radius ratio on the polymerization and drop of droplets on the heterogeneous surface was ana- lyzed． The results show that: ( 1) The heterogeneous surface，to a certain extent，can induce droplets of corre- sponding size to polymerize and drop． In addition，the size range of the droplets can be expanded by increasing the contact angle in the middle region． ( 2) The bigger the difference of the contact angle ( Δθ) of the heterogeneous surface，the faster the droplets polymerize，and the stronger the spreading ability of the droplet on the wall surface become，the smaller the longitudinal oscillation amplitude． ( 3) Within a certain range，the larger the radius ratio of droplets，the larger the internal pressure difference between the two droplets，and the faster the two droplets polymerize，and the droplet can gain additional kinetic energy and fall off the wall surface．

Traffic & Transportation Engineering

CP-CS Fusion Model for On-Ｒamp Merging Area on the Highway



WEN Huiying, WU Jiabin, QI Weiwei, et al

2020, 48(2):  50-57.  doi:10.12141/j.issn.1000-565X.190227

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A CP-CS fusion model that considers both conflict probability ( CP) and conflict severity ( CS) was pro- posed to effectively evaluate the traffic safety of existing or pre-built on-ramp merging areas on the highway． Firstly， the conflict probability model was established considering the impact of vehicle micro-running characteristics on traffic conflicts． Furthermore，the statistical data were used to integrate the conflict probability and conflict severity，so as to construct the CP-CS fusion model． Finally，based on the observation data，SSAM traffic conflict simulation analysis was carried out to verify the effectiveness of the proposed model． Moreover，a case study was introduced to reveal the evolution mechanism of risk coefficients in the merging areas，and illustrate the safety level of the merging areas under various optimization schemes． The experimental results show that the proposed model can improve the safety level of the existing or pre-built on-ramp． And there is a relatively higher traffic efficiency and safety level in the merging areas when the speed of traffic flow on the mainline is smaller than 27 m /s and the traffic flow is less than 1000 veh /h．

Experimental Investigation on Concrete Pipe Culvert Ｒeinforced by Small Corrugated Steel Pipes



LI Baijian, ZHU Liangsheng, LI Yong, et al

2020, 48(2):  58-68.  doi:10.12141/j.issn.1000-565X.190184

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In order to better understand the performance of the concrete pipe culvert reinforced by corrugated steel pipes，experiments were conducted on existing reinforced concrete pipes to determine the test-loading capacity of five specimens and understand the role of corrugated steel pipes． The influence of eccentric reinforcement on the loading capacity of the slip-lined pipe was explored and concluded with an approach to estimate the loading capacity of the reinforced pipes． The results show that the loading capacity of the concrete pipe culvert reinforced by corru- gated steel pipes mainly depends on the concrete pipes and the grout，and corrugated steel pipes plays a very small role． The loading capacity of an eccentric reinforced pipe was lower than that of a concentric reinforced pipe． The improved fully slip approach is reasonable，and the errors between the theoretical results calculated with the ap- proach for analyzing a vertical eccentric reinforced pipe proposed in this paper and experimental results is less than 22. 3% ．

SOC Estimation of Li-Ion Power Battery Based on STEKF



TIAN Sheng Lü Qing LI Yafei

2020, 48(2):  69-75.  doi:10.12141/j.issn.1000-565X.180562

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A method based on strong tracking extended Kalman filter ( STEKF) with multiple suboptimal fading factors was proposed to accurately estimate the state of charge ( SOC) of EV power batteries online． Taking a lithi- um-ion battery as the research object，the second-order ＲC equivalent circuit model of a lithium-ion battery was es- tablished based on its external characteristics and related mechanism． Then the least square method was used to identify the model parameters，and the STEKF nonlinear state space equation of the battery was established accor- ding to the equivalent circuit model． Finally，the simulation was carried out under ECE15 condition． The results show that the error of STEKF in estimating battery SOC is kept within 2% ，so this method can estimate battery SOC accurately．

Influence of Parked Car Ventilation Parameters on Driver Compartment Cooling after Hot Soak



GUO Peng, HU Xingjun, GAO Hao, et al

2020, 48(2):  76-83.  doi:10.12141/j.issn.1000-565X.180507

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The relevant parameters in the process of parking ventilation were studied to obtain the parameters that are helpful to enhance the effect of parking ventilation． Firstly，a model experiment was used to verify the accuracy of hot soak and ventilation cooling simulation． Then，under the conditions of model experiment，the cabin hot soak and ventilation process was simulated，and the driver compartment cooling effects under different parked car venti- lation parameters were compared． The results show that，after hot soak，the cooling effect is obvious in the first 3 minutes，and the increase of air volume is helpful for cooling，but the effect is not obvious when the air speed exceeds 250 m3 /h． In addition，adjusting the air volume distribution ratio and increasing the air flow with upward deflection can enhance the cooling effect．

Pavement Sealed Crack Detection Method Based on Improved Faster R-CNN



SUN Zhaoyun, PEI Lili, LI Wei, et al

2020, 48(2):  84-93.  doi:10.12141/j.issn.1000-565X.190421

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Pavement sealed cracks have significant impact on service life of pavement． A new method for pavement sealed crack detection based on improved faster R-CNN was proposed，aiming at solving the current lack of sealed crack detection technology． Firstly，the marked sample data set of pavement sealed crack was constructed based on the augmented sealed crack image set． Then they were divided into training set，verification set and test set accor- ding to the ratio of 6∶2∶2． Next，faster R-CNN model was employed in sealed cracks detection． Given that the faster R-CNN model has the demerits of miss detection and inaccurate positioning of sealed cracks，it was combined the feature extraction layers of VGG16，ZFNet and ＲesNet 50 networks． The results show that the detection accuracy of the VGG16 and faster R-CNN combination models can reach 0. 9031，which is the highest． Then，further im- provement was made by increasing the aspect ratio of the anchor of the sealed crack． The improved detection accu- racy reaches 0. 9073 and the original miss detection target can also be detected． Finally，detection and positioning accuracy between improved faster R-CNN and YOLOv2 model was compared． The result shows that improved faster R-CNN model can significantly enhance both detection and positioning accuracy．

Fluid Power & Electromechanical Control Engineering

Research Development of Soft Robots



WANG Haitao PENG Xifeng LIN Benmo

2020, 48(2):  94-106.  doi:10.12141/j.issn.1000-565X.190685

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Soft robots are made of soft materials and can be freely changed in size. Compared with rigid robots, soft robots own merits such as high flexibility,adaptability and safely human-machine interactivity.They have been favored by researchers at home and abroad for their broad application prospects in the fields of industry,agriculture,medical care, disaster relief,etc. The materials，production methods，drive methods，application fields，sensing and control methods of soft robots were reviewed. The new development in soft robots materials and production methods were introduced. According to drive methods,soft robots were divided into fluid-driven robots,intelligent material-driven robots，and chemical reaction-driven robots.In addition, their characteristics and typical structure were summarized. The modeling method and control strategy of the soft robots were introduced and analyzed. It concludes that developingvariable stiffness materials,efficient manufacturing and precise control methods is a promising directions of soft robot research.

Extension Knowledge Push Model for Automobile Engine Design



WANG Tichun HUA Yang WU Yong

2020, 48(2):  107-115.  doi:10.12141/j.issn.1000-565X.190694

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A extension knowledge push model of automobile engine design was studied, aiming Aiming at at the problem that designers have a large demand and different requirements for design knowledge in the process of automobile engine collaborative design，the extension knowledge push model of automobile engine design is studied. Firstly，the extension push architecture of automobile engine design knowledge iwas established，and the design flow framework of the vehicle engine design extension knowledge push model iwas given. Then，,the extension element model of automobile engine design knowledge iwas established and fuzzified. Based on this，the construction process of the automobile engine design extension knowledge base iwas put forward. Finally，, the automobile engine knowledge push extension correlation function model was constructed based on the extension knowledge base，the automobile engine knowledge push extension correlation function model is constructed，,and then the extension knowledge push model for automobile engine design iwas established. The collaborative design results of collaborative design of thean automobile engine shows that the extension knowledge push model proposed for the automobile engine design is effective and feasible.

Research on Energy Saving of Linear Actuator Based on Hydraulic Transformer



JIANG Jihai, DU Zhi, SHEN Wei, et al

2020, 48(2):  116-121,136.  doi:10.12141/j.issn.1000-565X.190686

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The hydraulic transformer can theoretically control the speed of the linear actuator without throttling loss and can recover and reuse the energy of the load. In order to improve the energy efficiency of the hydraulic transformer，, thea total efficiency model of the energy-saving system iwas designed in this paper. Based on To achieve the highest total efficiency，, the numerical value of the hydraulic accumulator volume iwas calculated by optimization algorithm，and t. The variation curve of gas pressure in the process of energy recovery iwas analyzed，, and the parameter of the hydraulic accumulator was the parameter matching of the hydraulic accumulator is completed. The Simulinkmathematical model of Simulink for of energy-saving system iwas established. The speed of movement was controlled Twith the fuzzy PID control strategy is used to control the motion speed when the load is falling. The simulation results show that the control strategy performs well in speed controlcan well control the motion speed.

Pneumatic Control Branch Modeling and Friction Compensation Test of New Mooring Mechanism



ZHANG Wei, LI Chunchao, LI Zhiyuan, et al

2020, 48(2):  122-128.  doi:10.12141/j.issn.1000-565X.190687

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Under the research background of the pneumatic control system of new mooring mechanism，taking its single pneumatic branch as an example，the dynamic mathematical model of proportional pressure valve control cy-linder was established and verified by experiments． Given the control mode of independent load port，namely，one cavity is position closed loop and the other is constant pressure control mode，the high frequency and low amplitude chatter signal was superimposed on the control signal of the constant pressure chamber to compensate the friction force． The simulated and experimental results show that chatter compensation improves the positioning accuracy of the system from 1. 1mm to 0. 5mm．


Optimization Analysis of Key Structure of Gas-Liquid Two-Phase Micro-Nano Bubble Generator



GAO Dianrong SUN Yanan ZHANG Zongyi

2020, 48(2):  129-136.  doi:10.12141/j.issn.1000-565X.190688

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In order to optimize the key structure of a gas-liquid two-phase micro-nano bubble generator,a three-dimensional model of the generator was established and theits principle of the generator was analyzed. The finite element simulation software FLUENT iwas used to simulate the flow field of the generator under different working pressures. The simulation results show that , when the inlet pressure is 1.5MPa, the generator can generate the largest number of bubbles generated when the inlet pressure of the generator is 1.5MPa is t. he most and wWhen the inlet pressure of the generator is 0.5，1.0，1.5 and 2.0 MPa , respectively， the proportion of bubbles with diameters around 1nm is 41.9%，53.3%，73.2% and 69.6% respectively. The influence of the size of 4 key structures，, the diameter of flow chamber，, the large/small diameter of the expansion chamber and the diameter of the swirl chamber， on the diameter and quantity of the bubble was explored，and , and the reason of the related influence was analyzed. The results show that , when the inlet pressure is 1.5 Mpa，the micro-nano bubble generator produces the largest number of micro-nano bubbles and the most uniform particle size. Appropriately increasing the diameter of flow chamber and the diameter of the swirl chamber is beneficial to improvefor the performance of the micro-nano bubble generator，, and changing the large/small diameter of the expansion chamber has no significant effect on improving its performance.

Fluid-Solid Coupling Modal Analysis of Sessile Droplets



SHI Guangfeng HUO Mingjie WANG Zitao

2020, 48(2):  137-142,150.  doi:10.12141/j.issn.1000-565X.190692

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A new finite element modeling method based on fluid-solid coupling was proposedIn order to to solveresolve the modeling and solvingution problems of sessile dropletsimulate modal analysis， a new finite element modeling method based on fluid-solid coupling is proposed.Using the method of fluid-solid coupling separation modeling, the surface tension of the fluid iwas equivalent to a film structure. Then the finite element simulation model of the sessile droplet iwas set upbuilt， , simulating the actual working condition and giving the known structural constraint and coupling constraint.The theoretical value and simulation value of natural frequency， ,characteristic array and maximum change of mass center awere analyzed and compared.It is shown The results show that the simulation natural frequency of the 2-5 order solid droplet is in accordance withlarger than the calculated results of by Rayleigh's theory，, which is in consistent with proved byresults in existing literature. The 2-54 order vibration spectrum of the solid droplet obtained by the finite element simulation is consistent with the vibration spectrum of the Chun-Ti Chang experiment in literature，.and tThe maximum displacement of the center of mass obtained by the droplet simulation is less than 15% of the theoretical calculatcalculatioedn value.

Internal Flow Field Analysis and Experimental Research of a Vane Oil Pump with Uneven Vanes Spacing



HE Shanghong, XIAO Shixuan, LIU Xiang, et al

2020, 48(2):  143-150.  doi:10.12141/j.issn.1000-565X.190689

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Based on RNG k-ε turbulent model，, the internal flow field of a vane oil pump with different vanes spacing was simulated by computational fluid dynamics software，t. The steady flow characteristic curve was obtained. And it is and compared with the experimental results. Considered the effectinfluences of different vanes spacing configuration，, the pressure pulsation at each monitoring points of internal flow field was analyzed in frequency domain. The results show that，compared with the even vane spacing configuration of even vanes spacing，the energy amplitude of pressure pulsation in pump outlet and oil pressure cavity decreases at the fundamental frequency multiple frequency，, and and decreases obviously at the third harmonic wave. The pressure pulsation and noise test analysis awere carried out on the experimental prototype. The test results show that，, compared with the even vane spacing configuration, the uneven vanes spacing configuration can reduce the pressure pulsation of the vane oil pump and the noise value of third and fourth harmonic is reducing by wave comparing with the regular vanes spacing configuration.