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    Development History and Future Trends of Numerical Control Machine Tools
    LIU Qiang,
    China Mechanical Engineering    2021, 32 (07): 757-770.   DOI: 10.3969/j.issn.1004-132X.2021.07.001
    Abstract624)      PDF (11426KB)(744)       Save
     From the viewpoints of industrialization and technology development, the paper summarized the revolutionary history of machine tools and the development processes of NCMT, with the analysis of the kernel technologies of NCMT. The development process of NCMT in China was divided into 3 periods, initial development, consistent technical research and industrialization, and highspeed development, transformation and upgrading as well. The milestone events and achievements were introduced. The industrial scale of NCMT all over the world and the advanced NCMT technologies in several developed countries were presented, followed by the comparative analysis of respects relative with NCMT at home and abroad. Finally, the future development trends were summarized prospectively.
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    Thoughts on Health Management and Condition-based Maintenance of Rolling Stocks
    ZHANG Weihua, LI Quanfu, SONG Dongli
    China Mechanical Engineering    DOI: 10.3969/j.issn.1004-132X.2021.04.001
    Accepted: 05 March 2021

    Plunge Milling of Titanium Alloys Based on Machine Learning and Multi-objective Optimization
    WENG Jian, ZHUANG Kejia, PU Donglin, DING Han,
    China Mechanical Engineering    2021, 32 (07): 771-777.   DOI: 10.3969/j.issn.1004-132X.2021.07.002
    Abstract270)      PDF (3242KB)(288)       Save
    Based on the experimental work and optimization research of plunge milling of titanium alloys, a hybrid method integrated with machine learning and multi-objective optimization algorithm was proposed herein to optimize the processing parameters considering material removal rate and cutting force as objectives. Spindle speed, radial cutting width, cutting step and feed per tooth were used as test variables. Taguchi method was used to reduce the number of test variable groups. The performance of the model given by machine learning was compared with traditional first-order and second-order regression models. Results show that machine learning has a better performance in prediction accuracies and the distributions of solutions. Four algorithms(MOEA/D, NSGA-Ⅱ, SPEA2, and NSPSO) were used and compared in solving the problem, and NSGA-Ⅱ shows a better comprehensive performance. Finally, the optimal results were compared with the initial reference. Results show that the optimal results may improve the material removal rate and reduce the cutting forces, which may help to achieve the goal of efficient and stable machining.
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    Two-way Fluid-Solid Coupling Simulation and Experimental Research of Sealing Rings Based on MpCCI Method
    GONG Ran, ZHANG Zhenyu, CHENG Zhigao, XU Yi, ZHANG He
    China Mechanical Engineering    2021, 32 (14): 1639-1646.   DOI: 10.3969/j.issn.1004-132X.2021.14.001
    Abstract247)      PDF (5466KB)(262)       Save
    To predict the fluid-solid coupling characteristics of sealing systems in transmission of heavy-duty off-road vehicles, the stress state of sealing rings in small confined spaces and the flow characteristics in flow fields of rotating sealing gaps were taken into account, and then the numerical models of two-way fluid-solid coupling for sealing systems were established and the solving methods were presented. The multi physics code coupling tool MpCCI was combined with FLUENT and Abaqus to carry out the numerical calculations of two-way fluid-solid coupling of rotary sealing systems. According to the fluid-solid coupling calculations, the flow states of oil in flow fields of rotary sealing gaps were obtained. The effective characteristics of sealing ring deformations on the leakage of rotary sealing systems and the friction torques of sealing rings were studied. The influences of transmission system working conditions on sealing ring performances were explored by two-way fluid-solid coupling dynamic simulation. Experimental investigations were performed in sealing performance test rig for sealing rings of vehicle transmission systems. Comparisons of numerical and experimental results show a good consistency of their change rules, which verifies the correctness of sealing fluid-solid coupling numerical models and calculation results.
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    Research Progresses of Basic Equipment Manufacturing and High-grade Integrated CNC Machine Tools
    HU Lai, ZHA Jun, ZHU Yongsheng, WEI Wenming, LI Dongya, LUO Ming, NIU Wentie, CHEN Yaolong
    China Mechanical Engineering    2021, 32 (16): 1891-1903.   DOI: 10.3969/j.issn.1004-132X.2021.16.001
    Abstract232)      PDF (26502KB)(345)       Save
    In order to solve the key problems faced by the aerospace manufacturing fields and improve the service capability for the industries,the machine tool industry proposed to build an innovative capability platform for high-grade CNC machine tools in the field of aerospace manufacturing. The research progresses in four aspects of basic assembly manufacturing and high-grade CNC machine tools were summarized about the innovation platform, including: motorized spindle unit technology(dynamic analysis of high-speed spindle—tool handle—tool system, digital simulation and prototype modal verification analysis); machine tool design(rigid-flexible coupling—electromechanical coupling dynamics of linear axis feed system, verification and analysis of electromechanical coupling dynamic model of multi-axis linkage and high-speed five-coordinate hybrid machining equipment and swing/rotary feed system, innovative structural design of MTC1000 boring, milling and grinding composite machining center); machine tool control(verification and analysis of high-speed start-stop residual vibration suppression technology) and machine tool verification(analysis of field data acquisition, mapping and storage technology for high-speed machining of aerospace structural parts). Finally, the future research trends were prospected.
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    Design of a Kind of Multi-dimensional Attitude Adjustment and Vibration Isolation Platform Based on 4-UPS/CPC Parallel Mechanisms#br#
    ZHANG Ying, SUN Hao, MA Shuaishuai
    China Mechanical Engineering    2021, 32 (13): 1513-1522,1529.   DOI: 10.3969/j.issn.1004-132X.2021.13.001
    Abstract227)      PDF (9410KB)(186)       Save
     A kind of multi-dimensional attitude adjustment and vibration isolation platform (MDAA&VIP) was presented for the wheel legged robot carriers. With 4-UPS/CPC parallel mechanisms as the main body and spring damping module as supplementary, the functions of attitude adjustment and vibration isolation were combined in the proposed MDAA&VIP to meet the needs of attitude adjustment and vibration isolation during the working processes of the carriers. Taking the combination of working space, static stiffness and dexterity as the objectives, and the structural parameters of the 4-UPS/CPC parallel mechanisms were optimized. The road spectrum model was established and the length of each limb needed to keep the upper platform horizontal was predicted by using the differential prediction algorithm when the carriers walked on the C-level roads. The effectiveness of the attitude adjustment function of the designed platform was verified by simulations. The vibration model of multi-dimensional vibration isolation system was established, and the vibration response of the system was studied by theoretical and simulation methods under forced vibrations. The results show that the isolation rates of the platform in five degrees of freedom directions are above 57%. The prototype of vibration isolation platform was designed and the experimental system was set up, and the vibration isolation experiments in X, Y and Z directions were carried out. The experimental results show that the designed MDAA&VIP has good vibration isolation performance, and the vibration isolation rates in the three test directions are more than 50%.
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    Integrated Vehicle Chassis Nonlinear Robust Constrained Optimization Control Based on Dissipative Theory
    ZHANG Jiaxu, ZHAO Jian, SHI Zhengtang, YANG Xiong
    China Mechanical Engineering    2021, 32 (08): 883-889.   DOI: 10.3969/j.issn.1004-132X.2021.08.001
    Abstract218)      PDF (4376KB)(225)       Save
    A nonlinear robust controller for integrated control of active front wheel steering subsystem and direct yaw moment control subsystem was presented based on dissipative theory. Firstly, an integrated vehicle chassis control model including body lateral and yaw motion degrees of freedom was established, and the un-modeled dynamics and the measurement errors both of the model parameters and feedback signals were regarding as the additive and multiplicative uncertainties of the system. Secondly, an integrated vehicle chassis nonlinear L2-gain control law was designed based on dissipative theory to suppress the effect of the additive uncertainties on the system performance, and an adaptive law was designed based on projection correction method to estimate and compensate the multiplicative uncertainties. Thirdly, the sequential quadratic programming method was used to realize the constrained optimal allocation of the corrected yaw moment, which was the output of the proposed integrated vehicle chassis nonlinear L2-gain control law. Finally, the feasibility and effectiveness of the proposed integrated vehicle chassis nonlinear robust controller were verified via vehicle dynamics simulation software. 
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    Review on Management at Mechanical Design and Manufacturing Discipline of NSFC in 2020
    YE Xin, LI Hongwei, YANG Zhibo, LAI Yinan
    China Mechanical Engineering    2021, 32 (06): 631-637.   DOI: 10.3969/j.issn.1004-132X.2021.06.001
    Abstract208)      PDF (1672KB)(147)       Save
    The applications, evaluations and funding of projects at mechanical design and manufacturing discipline (division Ⅱ of engineering science) of the NSFC in 2020, as well as the research progresses and achievements of the executing and finished projects were reviewed. Specific measures of Mechanical Design and Manufacturing Discipline were stated, such as controlling the COVID-19, performing the new age reform of scientific fund, launching academic exchange and cooperation, enhancing talent cultivation and academic team construction and so on. Finally, the strategic researches on the 14th five-year and medium and long-term development plan were briefly introduced.
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    Rolling Bearing Fault Diagnosis Method Based on Adaptive Autogram
    ZHENG Jinde, WANG Xinglong, PAN Haiyang, TONG Jinyu, LIU Qingyun
    China Mechanical Engineering    2021, 32 (07): 778-785,792.   DOI: 10.3969/j.issn.1004-132X.2021.07.003
    Abstract197)      PDF (5363KB)(168)       Save
    In Autogram method, the signal spectrum was divided by the maximum overlap discrete wavelet packet transform, and the signals in the frequency band corresponding to the maximum kurtosis value were selected for diagnostic analysis. However, the method followed the binary tree structure when the frequency band was divided, and the division area of this structure was fixed. A fault diagnosis method of rolling bearings was proposed based on adaptive Autogram to solve this problem. The improved empirical wavelet transform was used as the basis of adaptive Autogram. In this process, the original signal Fourier spectrum was enveloped and smoothed and then segmented, thus achieving the purpose of frequency band was adaptively divided by Autogram. The simulation signals and experimental data were analyzed through the proposed method, and the analysis results were compared with the existing fast kurtogram and Autogram. The results show that the optimal demodulation frequency band may be accurately detected by the proposed method, and the fault characteristics are more obvious.
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    Design of Wearable Rigid and Soft Combined Hand Rehabilitation Devices
    LIU Dong, WANG Minghao, BI Cong, SHUI Shengcai, CONG Ming, DU Yu
    China Mechanical Engineering    2021, 32 (08): 930-937.   DOI: 10.3969/j.issn.1004-132X.2021.08.007
    Abstract192)      PDF (7531KB)(111)       Save
    Hand rehabilitation devices were used for hand function recovery treatment. Rigid devices were not flexible enough, poor fitting, and easy to cause secondary damage, and soft devices had small driving forces and the complex soft devices were not easy to make. In order to overcome the shortcomings of rigid devices and soft devices, a wearable hand rehabilitation device combining soft joints and rigid knuckles was proposed. Firstly, the biological structure of human hand was analyzed, the soft joint structure was designed and its bending characteristics were analyzed. The pneumatic finger actuator was designed based on rigid and soft combination, and finite element stress and deformation analyses were carried out. Then, the soft silicone joint mould and hand rehabilitation device were manufactured. Finally, the test platform for pneumatic finger actuators was built to test the bending characteristics and fingertip forces of the rigid and soft combined finger actuators, and hand rehabilitation devices were used to grab objects of different shapes. Results show that the designed wearable hand rehabilitation devices may realize the rehabilitation training of hand grasping and holding. 
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    Overview of Micro Friction to Macro Dynamics for Bolted Connections
    CAO Junyi, LIU Qinghua, HONG Jun
    China Mechanical Engineering    2021, 32 (11): 1261-1273.   DOI: 10.3969/j.issn.1004-132X.2021.11.001
    Abstract188)      PDF (7675KB)(276)       Save
    As a typical mechanical assembly method, bolted connections played an important role in the design and operation of key mechanical equipment in the field of aerospace, military weapons, energy and chemical equipment and transportation industry. Moreover, due to the introduction of the nonlinear factors of stiffness and damping by bolted connections, new challenges in performance predictions and operation reliability were come into being to propel us to comprehensively understanding the characteristics of bolted connections from interface micro friction to macro structural dynamics. Therefore, the micro-macro dynamics of bolted connections reviewed and the fractal characterization modeling, statistical summation modeling and Iwan modeling methods of bolt joint friction constitutive model were summarized. Several experimental benchmarks for testing the friction energy consumption of bolted connections in the world were analyzed in detail. The latest research progresses of nonlinear modeling, parameter identification, numerical simulation and structural health monitoring in the macro dynamics of bolted connections were discussed, and the development trend of this field was prospected.
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    Bearing Fault Diagnosis Method Based on Small Sample Data under Unbalanced Loads#br#
    HE Qiang, TANG Xianghong, LI Chuanjiang, LU Jianguang, CHEN Jiadui
    China Mechanical Engineering    2021, 32 (10): 1164-1171,1180.   DOI: 10.3969/j.issn.1004-132X.2021.10.004
    Abstract184)      PDF (6051KB)(135)       Save
    Aiming at the problems that the bearing vibration signals were easily disturbed by unbalanced load and the small number of bearing fault samples, a bearing fault diagnosis method based on WGAN-GP and SeCNN was proposed. The bearing vibration signals were processed by short-time Fourier transform to get the time-spectrum samples that were easy to be processed by WGAN-GP, which were divided into training set, validation set and test set. Then the training set was inputted into WGAN-GP for adversarial training, new samples were generated with similar distribution to the training samples, and added to the training set to expand the training set. The expanded training set was input into SeCNN for learning, and the trained model was applied to the test set and output the fault recognition results. The analysis of the CUT-2 platform unbalanced load bearing data was carried out, and the experimental results show that the proposed method may accurately and effectively classify the bearing faults.
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    Development Status and Perspective Trend of Motor Cooling Systems
    TANG Yong, SUN Yalong, GUO Zhijun, ZHANG Shiwei, YUAN Wei, TANG Heng, LIANG Fuye
    China Mechanical Engineering    2021, 32 (10): 1135-1150.   DOI: 10.3969/j.issn.1004-132X.2021.10.001
    Abstract178)      PDF (15987KB)(270)       Save
    Cooling systems with high heat dissipation efficiency were the important foundations of restraining motor temperature rise, improving motor operation stability and prolonging motor life. The development status of air cooling, liquid cooling and evaporative cooling was introduced, which were commonly used in the cooling systems for motors. The advantages, disadvantages and application ranges of various motor cooling systems were analyzed and discussed. The research progresses in improving the cooling efficiency of motor heat dissipation system at home and abroad were reviewed. By combining the additional thermal circuit enhanced motor cooling system and the phase change heat dissipation technology, a new scheme to improve the heat dissipation efficiency of motors using phase change heat transfer devices was proposed. Finally, the development trend of the motor heat dissipation systems was predicted and prospected scientifically. 
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    Review on Repair Technologies for Key Part Remanufacturing of Shield Machines
    LI Fangyi, QI Xiaoxia, LI Yanle, WANG Liming, DU Jiyu, XU Jingwei, MENG Xiaoning
    China Mechanical Engineering    2021, 32 (07): 820-831.   DOI: 10.3969/j.issn.1004-132X.2021.07.009
    Abstract169)      PDF (4769KB)(171)       Save
    The development situation of shield machine remanufacturing in China was expounded, and the development shortages and challenges were pointed out. The damage forms and the repair methods of key parts of shield machines, such as main bearing, cutter and cutter head, hydraulic system, reducer, screw conveyer were summarized. The potential and advantages of additive repairing technologies such as laser cladding, thermal spraying, cold spraying and cold welding in shield machine remanufacturing were analyzed. The future development trends of shield machine remanufacturing were finally provided.
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    Kinematics of a Novel Three-translation and One-rotation(3T1R) Semi-symmetry Parallel Manipulator
    SUN Chiyu, SHEN Huiping, YUAN Juntang, YANG Tingli
    China Mechanical Engineering    2021, 32 (06): 638-647.   DOI: 10.3969/j.issn.1004-132X.2021.06.002
    Abstract167)      PDF (8376KB)(119)       Save
    A novel 3T1R parallel manipulator 2RRPaR+2RSS synthesized was proposed based on the topological structure design theory and method of POC equation. The structural analysis was described, the DOF and the POC set of the mechanisms were calculated, and proving that the coupling degree is equal to 2. According to the structural characteristics of the mechanisms and the constraint conditions of the bar, the forward kinematics was established by two-dimensional search method, the inverse kinematics was derived, and the correctness of them was verified. Then, based on the inverse kinematics, the 3D model of the workspace of the mechanisms was calculated by MATLAB programming, and a group of section shapes of different sections in Z direction were obtained. Meanwhile, the rotation ability was analyzed at the section where Z=1000 mm. Finally, the singularities of the mechanisms were analyzed based on Jacobian matrix. The results show that when the main dimensional parameters are the same, the working performances of the proposed 2RRPaR+2RSS parallel manipulator are superior than that of H4 mechanism. Compared with H4 mechanism, the workspace and rotation capability of the proposed parallel manipulator are increased by 27.87% and 4.35% respectively.
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    Flexible Job Shop AGV Fusion Scheduling Method Based on HGWOA
    LI Xixing, YANG Daoming, LI Xin, WU Rui,
    China Mechanical Engineering    2021, 32 (08): 938-950,986.   DOI: 10.3969/j.issn.1004-132X.2021.08.008
    Abstract166)      PDF (8426KB)(102)       Save
    Considering the AGV only participated in loading-unloading and transport in production processes of flexible job shop scheduling problem, an integrated scheduling model was proposed to ensure the integrated optimization of AGV path planning and flexible job shop scheduling. Then a two-dimensional vector coding scheme was applied based on two sub-problems of process sequencing and machine selection, and an AGV arrangement strategy was proposed based on the principle of first service in the decoding processes. The whale optimization algorithm was discretized, and a variety of targeted population initialization strategies were designed. The crossover operations and mutation operations of genetic algorithm were introduced to improve global search capability of whale optimization algorithm. The local search algorithm was embedded to achieve the balance between global search and local search. Then, a HGWOA was built up to solve the fusion scheduling model. The performance of the algorithm was verified by classical test examples. The parameters of the algorithm were optimized by orthogonal tests. Results show that HGWOA may achieve better results in solving AGV fusion scheduling problem of flexible job shops.
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    Predictive Control of Plantar Force and Motion Stability of Hydraulic Quadruped Robot
    LI Bing1;ZHANG Yongde1;YUAN Lipeng2;ZHU Guangqiang3;DAI Xuesong1;SU Wenhai3
    China Mechanical Engineering    DOI: 10.3969/j.issn.1004-132X.2021.05.003
    Accepted: 17 March 2021

    Design and Master-Slave Control of Dexterous Hands with Five Fingers Based on Tendon-sheath Transmission#br#
    YIN Meng, XU Zhigang, ZHAO Zhiliang, HAN Wei,
    China Mechanical Engineering    2021, 32 (08): 951-959.   DOI: 10.3969/j.issn.1004-132X.2021.08.009
    Abstract158)      PDF (11590KB)(219)       Save
    In order to make the dexterous hand more light and anthropomorphic, a 19 joints dexterous hand driven by steering engine through tendon-sheath transmission was designed. Firstly, the configuration of the dexterous hands was determined by referring to the human hand joints. Joint decoupling and drive postposition were realized using tendon-sheath transmission. Joint mechanisms and driving integration were designed separately. Then, a multi-fingers kinematic model of dexterous hands was established and the workspace was analyzed. The master-slave tracking control of grasping was realized based on the sensors and master-slave mapping algorithm. Finally, a prototype of dexterous hand was built, and the joint motion experiments and grasping control experiments were carried out. Experimental results show the feasibility of applying the tendon-sheath transmission to dexterous hands. The dexterous hands may grasp a variety of objects based on master-slave control.
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    Prediction of Cutting Forces for Chamfered Inserts Based on Modified Slip-line Field Model#br#
    ZHUANG Kejia, HU Cheng, DAI Xing, PU Donglin, DING Han
    China Mechanical Engineering    2021, 32 (08): 890-906.   DOI: 10.3969/j.issn.1004-132X.2021.08.002
    Abstract157)      PDF (16134KB)(256)       Save
    Based on the material plasticity slip-line theory and flow state analysis ahead of tool edge, a modified slip-line field model was proposed considering material stagnation zone (dead metal zone), and pre-cut region in negative-rake-angle cutting processes with chamfered insert. Furthermore, an iterative sollution to material shear flow stress and edge front cutting geometry was suggested. The relationships of chamfered edge geometry and slip-line field geometry were disclosed. An analytical approach to the orthogonal cutting force prediction method was developed by applying the presented model to the cutting processes with chamfered insert. Verifications including finite element simulations and orthogonal cutting trials were carried out for the modified slip-line field model and prediction method of cutting forces. Average errors are all less than 10% in comparisons of predictions and simulations as well as measurements. Results provide references for investigating the influences of edge geometries on material flow characteristics and tool cutting performances.
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    Similarities Detection and Analysis of Tire Patterns Based on Similarity Theory
    LI Hongling, DONG Yude, HUANG Zhihao, GAO Haoyu, TAO Senwang
    China Mechanical Engineering    2021, 32 (14): 1646-1652.   DOI: 10.3969/j.issn.1004-132X.2021.14.002
    Abstract157)      PDF (4852KB)(135)       Save
    Based on the similarity theory, the characteristics of tire pattern structures were analyzed. Using image processing method such as gray histogram, aHash algorithm and co-occurrence matrix method, a 2D similarity detection system for tire patterns was built in MATLAB software. The similarities of the existing tire patterns were detected by the system, and the similarities of the specified patterns with local change and the original patterns were detected. Results show the stability and the reliability of the system. It may provide a basis for similarity quantization of different tire patterns.
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    Research on Metamorphic Self-recovery Strategy and Characteristics of Metamorphic Quadruped Robots after Overturning#br#
    WANG Shengjie, DAI Jiansheng,
    China Mechanical Engineering    2021, 32 (11): 1274-1282,1292.   DOI: 10.3969/j.issn.1004-132X.2021.11.002
    Abstract155)      PDF (11804KB)(364)       Save
    When the robots were working in unmanned environments, it was difficult to avoid overturning and loss of movement due to external forces and terrains. Therefore, it was necessary that the robots had the self-recovery ability. In the static self-recovery method, the traditional recovery method could only be achieved by the movement of the legs. Based on the movable trunks of the metamorphic robots, different from traditional method a self-recovery strategy with the movement of the trunk was proposed when the quadruped robot overturned. The strategy used bionic inspiration to design the action and compared this method with the case of the trunk without metamorphosis from the perspective of force and energy. The optimized centroid trajectory and the shock absorption method were obtained. In addition, the simulation software and the prototype experiments were used to verify the feasibility of this method and it is proved that the strategy reduces the difficulty of achieving static self-recovery. Besides, experiments under different conditions prove that the strategy has certain stability and adaptability on different terrains.
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    Solution of Inverse Kinematics for 6R Robots Based on Combinatorial Optimization Algorithm#br#
    JI Yangzhen, HOU Li, LUO Lan, LUO Pei, LIU Xubin, LIANG Shuang
    China Mechanical Engineering    2021, 32 (10): 1222-1232.   DOI: 10.3969/j.issn.1004-132X.2021.10.011
    Abstract152)      PDF (1672KB)(257)       Save
    In order to solve the problems of multiple solutions, low accuracy and poor generality in inverse kinematics, a combinatorial optimization algorithm was proposed to solve the inverse kinematics for all kinds of 6R industrial robots. The kinematics models of the robot were established according to the classical D-H method. The objective function of the inverse kinematics was constructed by minimizing the pose errors with the principle of motion stability, and its fitness function was designed by linear weighing-sum method. An improved whale optimization algorithm for inverse kinematics was developed by using four methods including chaotic mapping initializing population, nonlinear updating of convergence factor, adaptive inertia weight and simulated annealing strategy. The combinatorial algorithm took the results of the whale optimization algorithm as the initial value, and then the inverse kinematics solution satisfying the accuracy requirements was iterated by the Newton-Raphson numerical method. The results of simulation experiments indicate that the performance of the improved whale optimization algorithm is greatly enhanced. Compared with the direct use of whale optimization algorithm for inverse kinematics, the combinatorial optimization algorithm has the advantages of faster solution speed, better stability and ultra-high accuracy, which also proves that the proposed algorithm is feasible and effective for inverse kinematics problems.
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    Multi-objective Optimization of Cutting Parameters in Ti6Al4V Milling Processes Based on Finite Element Simulation#br#
    LI Yujia, HUANG Bing, LU Juan, ZHONG Qijing, CHEN Chaoyi, LIAO Xiaoping, MA Junyan
    China Mechanical Engineering    2021, 32 (13): 1555-1561,1570.   DOI: 10.3969/j.issn.1004-132X.2021.13.006
    Abstract148)      PDF (2850KB)(111)       Save
    In order to make the cutting processes meet the requirements of environmentally conscious manufacturing(ECM), for the quality index(surface roughness) and ECM index(energy consumption), aiming at the Ti6Al4V processes, the Gaussian process regression(GPR) method optimized by artificial bee colony (ABC) algorithm was used to established the finite element agent model, and the processing parameters satisfying the optimal machining objectives were obtained by using the multi-objective particle swarm optimization(MOPSO) algorithm. Deform-3D, a finite element simulation software which might reduce the testing cost was used to obtain the surface roughness and energy consumption data corresponding to each milling parameter combinations, and the effectiveness was proved by physical tests. Then, an improved GPR method was used to establish the prediction model based on the surface roughness and energy consumption of the finite element simulation data. The performance of the model was compared with that of the other two models, and the advantages of the improved model in accuracy and response time were proved. Finally, Pareto front of processing parameters with the goal of minimum energy consumption and excellent surface quality were obtained by MOPSO algorithm. The effectiveness of the ABC-GPR-MOPSO algorithm was verified by physical tests.
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    A Fault Diagnosis Method of Rotating Machinery Based on LBDP
    SHI Mingkuan, ZHAO Rongzhen
    China Mechanical Engineering    2021, 32 (14): 1653-1658,1668.   DOI: 10.3969/j.issn.1004-132X.2021.14.003
    Abstract147)      PDF (2566KB)(121)       Save
    Aiming at the problems of classification difficulty caused by multi-class and high-dimensional complex characteristics of rotor fault data, a LBDP dimensionality reduction algorithm was proposed. First of all,the mixed features of the rotor vibration signals were extracted from multiple angles in time domain, frequency domain and time-frequency domain,and the high-dimensional feature sets were constructed. The original feature sets were fused by LBDP algorithm, and the low-dimensional sensitive feature subsets which might best reflect the intrinsic information of the faults were selected. Then the low-dimensional feature subsets were input into K-nearest neighbor(KNN) classifier for training and fault classification. The effectiveness of the proposed method was verified by the vibration signal sets of a double-span rotor systems, and it is proved that the method may extract the local discriminant information comprehensively and make the difference among fault categories clearer. 
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    Investigation of Influences of Stator Can Deformations on Axial Flow Resistance in Annular Gap Flow
    WANG Shengde, YAO Zhenqiang, SHEN Hong
    China Mechanical Engineering    2021, 32 (17): 2017-2024.   DOI: 10.3969/j.issn.1004-132X.2021.17.001
    Abstract146)      PDF (7775KB)(257)       Save
    In order to predict the flow distribution between the upper and lower branches of the internal cooling circuit within a canned motor reactor coolant pump(RCP), the stator can deformations and the influences on axial resistance of the annular gap flow were studied. The deformed profile of stator cans under the high pressure was calculated with the finite element method and verified by experiments. The influences of stator can deformations on annular gap flow were studied by using computational fluid dynamics and a modified model for axial flow resistance evaluation was established by variable parameter analysis and mathematical fitting. Calculation result from the established model shows that, compared to ideal cylindrical state, 11% boundary deformation of the stator can under the rated working state of the RCP, will lead to 83% decrease of the axial flow pressure drop in the rotor and stator clearance.
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    Design and Mechanics Analytical Modeling of Vertical Multistage Displacement Amplification Mechanisms
    LIN Chao, SHEN Zhonglei, LI Pingyang, ZHENG Shan
    China Mechanical Engineering    2021, 32 (08): 908-915,937.   DOI: 10.3969/j.issn.1004-132X.2021.08.004
    Abstract140)      PDF (6496KB)(176)       Save
     Piezoelectric displacement amplification mechanisms were difficult to obtain large working strokes and high frequency bandwidth in vertical direction. Therefore, a new vertical multistage displacement amplification mechanism was proposed by integrating two compound rhombus-type mechanisms, two lever mechanisms and a rhombus-type mechanism. Analytical models of displacement amplification ratio and input/output stiffness were deduced by energy conservation method and elastic beam theory. The analytical model of natural frequency was derived based on Lagrange equation. The analytical model was verified by finite element method. The analytical model of displacement amplification ratio herein has a high prediction accuracy and may provide a reference for optimal design of vertical compliant stage with a large working stroke. After compared with several vertical displacement amplification mechanisms from references, the proposed vertical multistage displacement mechanism shows better static and dynamic performances, with a displacement amplification ratio of 43.29 and a relative high natural frequency of 561.28 Hz.
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    Modeling and Experimental Study on Cutting Forces of 2D Vibration Assisted Micro-milling
    SHANG Peng, HUANG Sishuo, LIU Xiaopeng, YANG Zhuang, LIU Teng, ZHANG Jianjun
    China Mechanical Engineering    2021, 32 (06): 648-657,665.   DOI: 10.3969/j.issn.1004-132X.2021.06.003
    Abstract140)      PDF (8620KB)(104)       Save
    Based on the mechanics analysis method and the force model of oblique cutting element, considering the influences of tool run-out, size effect and cumulative effect on the instantaneous depth of cut in the actual cutting processes, combining the kinematics characteristics of 2D vibration assisted micro-milling, the instantaneous depth of cut model of 2D vibration assisted micro-milling was established according to the differences of cutting forces for shear areas and plough areas. In order to achieve the purpose of vibration assisted machining, based on the self-designed and optimized non resonant 2D compliant vibration stage, the corresponding 2D vibration assisted micro-milling tests of aluminum alloy Al6061 were carried out, the cutting force curves of Al6061 were simulated by MATLAB software, and the correctness of the established 2D vibration assisted micro-milling cutting force model was verified by comparative analysis. Finally, based on the established cutting force model, the influences of vibration amplitude and frequency on the milling forces were analyzed.
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    Design and Adsorption Performance Optimization of Non-contact Variable Magnetic Gap Type Permanent Magnet Absorption Mechanisms of Pipe Climbing Robots
    GUO Denghui, CHEN Yuan
    China Mechanical Engineering    2021, 32 (14): 1659-1668.   DOI: 10.3969/j.issn.1004-132X.2021.14.004
    Abstract139)      PDF (3267KB)(129)       Save
    A non-contact variable magnetic gap type climbing robot was designed, which was adaptive adsorb tubes with different diameters. A magnetic field distribution model and magnetic adsorption force model of adsorption mechanisms were established by vector magnetic position method and finite element method. Based on equilibrium equation of space force system, the mechanics model of the robot was established and the minimum magnetic adsorption force was obtained. Based on the theoretical model of magnetic field and magnetic adsorption force and Maxwell simulation, the optimal magnet width and magnetic adsorption force were obtained by discrete combination method. After comparing different magnetic fields and magnetic adsorption forces, when the optimal magnet width is as 80 mm, the magnetic attraction force per unit volume of approximate circular arc mechanisms is as 0.0078 N/mm3, which is larger than 0.0047 N/mm3 of rectangular magnet. The magnetic adsorption force satisfies the load requirements of the minimum magnetic adsorption force of 2100 N. Finally, the magnetic adsorption force characteristics of the magnetic adsorption mechanisms were obtained by experiments. The results prove the feasibility of the optimization design of magnetic adsorption mechanisms.
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    Study on Steady-state Heat Transfer of Soft Manipulators with Variable Stiffness Based on Low-melting-point Alloy Phase Transition
    WANG Fengxu, XING Zhiguang, YANG Pengpeng, LIN Jun, ZHAO Jianwen,
    China Mechanical Engineering    2021, 32 (07): 793-798.   DOI: 10.3969/j.issn.1004-132X.2021.07.005
    Abstract133)      PDF (2008KB)(74)       Save
    The steady-state heat transfer model for the soft manipulators with variable stiffness based on LMPA phase transition was established to calculate the temperature changing, heat transfer power of each parts and the convective heat transfer of water in the spiral coil during steady-state heat transfer. Then, the steady-state heat transfer process was simulated by COMSOL Multiphysics. The differences between simulation and analysis model are within 4.5%. The theoretical analysis and simulation may be used to guide the design of variable stiffness modules. 
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    Dynamics Characteristics of Rotor Systems under Magnetic Bearing Excitation
    LI Shengyuan, ZHENG Longxi
    China Mechanical Engineering    2021, 32 (08): 901-907.   DOI: 10.3969/j.issn.1004-132X.2021.08.003
    Abstract132)      PDF (4603KB)(102)       Save
    To analyze the vibration mechanism of the rotor systems excited by magnetic bearings, a calculation model for dynamics characteristics of a double-disk rotor system was established by using one-dimensional finite element method. The dynamics behaviors of rotor system under different types of magnetic bearing excitations were studied. Results show that the co-rotating sweep frequency exciting forces excite forward whirl mode of the rotor systems, while the counter-rotating sweep frequency exciting forces excite backward whirl mode. In both cases, the rotor system whirls in a circular trajectory. The unidirectional harmonic exciting force may be decomposed into the sum of co-rotating and counter-rotating exciting forces, therefore both of the backward whirl and forward whirl modes of the rotor system are excited and the rotor system whirls with an elliptical trajectory under the effect of unidirectional harmonic sweep exciting force. Under bi-directional harmonic sweep exciting forces, the whirl direction and whirl trajectory of the rotor system depend on the phase difference of the two exciting forces. Research results provide a theoretical basis for the selection of excitation scheme of magnetic bearings when evaluating the stability of rotor systems of high-pressure compressor.
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    Multi-objective Optimization and Decision-making Method of High Speed Dry Gear Hobbing Processing Parameters
    NI Hengxin, YAN Chunping, CHEN Jianlin, HOU Yuehui, CHEN Liang
    China Mechanical Engineering    2021, 32 (07): 832-838.   DOI: 10.3969/j.issn.1004-132X.2021.07.010
    Abstract131)      PDF (2160KB)(93)       Save
    To reduce energy consumption and improve gear hobbing quality, a multi-objective optimization and decision-making method of high-speed dry gear hobbing processing parameters was proposed based on improved multi-objective grey wolf optimization(MOGWO) algorithm and TOPSIS. The gear hobbing processing parameters were analyzed, and cutting parameters and hob parameters were taken as optimization variables. A multi-objective optimization model for minimum energy consumption and optimal gear hobbing quality was established. The improved MOGWO algorithm was used to optimize the model iteratively, and TOPSIS was subsequently utilized to make multi-attribute decision on the optimized processing parameters. Effectiveness of the proposed method was verified by experimental results.
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    Study on Infrared Image Enhancement of Wind Turbine Blades Based on Adaptive Differential Multiscale Morphology(ADMM)
    KANG Shuang, CHEN Changzheng, ZHAO Siyu, LUO Yuanqing, KONG Xiangxi
    China Mechanical Engineering    2021, 32 (07): 786-792.   DOI: 10.3969/j.issn.1004-132X.2021.07.004
    Abstract130)      PDF (8133KB)(64)       Save
    In order to improve the ability of infrared detection of internal defects of wind turbine blades and overcome the problems of low definition of infrared thermal images, uneven background illumination, and weak ability of detail recognition, an image enhancement algorithm was proposed based on ADMM. Different scale structural elements were selected as the operation objects in the expansion and corrosion operations, and the maximum contrast improvement coefficient ratio was used as the objective function of multi-scale and difference scale selection. The light and dark details of multi-scale images were extracted by using the advantages of open, close, and top-hat operations. Then, the differences between the white cap and the black cap were calculated to get the detail enhancement information, and the enhanced infrared images were obtained by fusing with the original images. Finally, the grayscale distribution of the image was adjusted to achieve the best visual effectiveness. Simulation results show that the algorithm has strong robustness and may effectively enhance the infrared image details under uneven illumination, improve the detection ability of infrared detection in wind turbine blades.  
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    Study on Tool Interface Behavior of Silicon Carbide Toughened Alumina-based Ceramic Tools in Cutting Inconel718 Alloy#br#
    HAO Zhaopeng, HAN Xue, FAN Yihang
    China Mechanical Engineering    2021, 32 (09): 1009-1016.   DOI: 10.3969/j.issn.1004-132X.2021.09.001
    Abstract130)      PDF (7110KB)(77)       Save
    Through macro experiments, it was found that during the cutting processes, the Al2O3/SiC interface of the tool breaks, and the macro mechanical properties of the material depended on the microstructure. Therefore, the molecular dynamics model for the cutting of Inconel718 nickel-based alloy with ceramic tool toughened alumina based on silicon carbide and the three-dimensional interface model of Al2O3/SiC were established to analyze the interface behaviors of the cutting processes of toughened alumina based on silicon carbide from the atomic scale. Based on the original potential function, the Morse potential function between the tool and the workpiece atoms, as well as between the matrix and toughening inside the tool was calculated, and the interface binding energy of single-phase Al2O3, single-phase SiC and complex phase Al2O3/SiC single interface was calculated respectively. Results show that compared with single phase interface, the complex phase Al2O3/SiC interface bonding strength is higher, SiC toughening can enhance the toughness and strength of the tools. However, during the cutting processes, the workpiece atom diffuses into the tool, and the interface bonding energy between the tool matrix and the toughened interface is calculated. It is found that the diffusion reduces the interface bonding strength of the tools and makes the tool fracture at the interfaces of Al2O3/SiC.
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    Kinematic Accuracy Analysis and Optimization Design for Spatial Steering Mechanisms with Joint Clearances#br#
    WANG Chengzhi, WANG Yunchao
    China Mechanical Engineering    2021, 32 (09): 1027-1034,1042.   DOI: 10.3969/j.issn.1004-132X.2021.09.003
    Abstract128)      PDF (1143KB)(79)       Save
     To evaluate the influences of the joint clearances, including the joint radial clearances and the rack moving direction inclination to lateral direction of vehicle, on the steering errors of a rack and pinion steering mechanism, the joint radial clearances in the steering mechanisms were treated as joint clearance link or variable length link, and then the kinematic model of the spatial steering mechanisms with the joint clearances and the analytical relationship between the rotation angles of kingpin axis and steering wheel were deduced by using the screw theory. An optimization model for the steering mechanisms was established by aiming at minimizing steering errors and taking the maximum values of pressure angles and the minimum value of the maximum steering angle as the constrained conditions. The kinematic analysis of an example shows that the forward and the return steering processes of the steering mechanisms with joint clearances have different steering errors and the return steering errors are larger than that of the forward steering; the steering errors at the moment of revering operation increase sharply; the increase of the joint clearance or the inclination of the rack may increase the minimum steering radius of the vehicle. Steering accuracy of the steering mechanisms with joint clearances may be improved by the optimal design considering the joint clearances. 
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    Structural Design Optimization of Spindle Unit of CNC Lathes for Energy Saving
    HE Jixiang, LI Congbo, LYU Yan, LI Juan
    China Mechanical Engineering    2021, 32 (11): 1330-1340.   DOI: 10.3969/j.issn.1004-132X.2021.11.009
    Abstract128)      PDF (9932KB)(76)       Save
    In order to reduce the energy consumption during the use of CNC lathes, an energy-saving structural optimization design method was proposed for the spindle units in the main drive system. Firstly, the power model of the spindle units was constructed and the dynamic and static performance indicators were analyzed. Then, the size parameters that had a large impact on the energy consumption, dynamic and static performance of the spindle units were selected as optimization variables, based on the uniformity test and sensitivity analysis, and the indicators were fitted by response surface method. Thirdly, the principal unit analysis method was used to reduce the function dimension, and an optimization model for energy-saving design of the spindle unit structures was established. Finally, physical experiments were used to verify the reliability of the simulation results, and the simulated annealing-particle swarm hybrid algorithm was used to solve the optimization model. The comparative results of the harmonious response analysis and the simulation experiments of the spindles before and after optimization show that the maximum deformation of the spindles is reduced by 1.67%, the second-order frequency is increased by 6.83%, and the un-load energy consumption is reduced by 3.69%. This optimization design method reduces the spindle energy consumption, and improves the dynamic and static performances of the spindles at the same time.
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    Charging Path Planning Strategy of Electric Vehicles with Integrating Dynamic Energy Consumption and Network Information
    LIN Xinyou, ZHOU Binhao, XIA Yutian
    China Mechanical Engineering    2021, 32 (06): 705-713.   DOI: 10.3969/j.issn.1004-132X.2021.06.010
    Abstract127)      PDF (7269KB)(72)       Save
    Aiming at the range anxiety problems of electric vehicles, taking the electric vehicles as the research objects, based on the “vehicle-road-network” intelligent system, the road topology model, impedance evaluation model and vehicle energy consumption model were established, the optimal driving time, optimal energy consumption and comprehensive optimization were as the objectives respectively, and the A* algorithm was used to plan the charging path of electric vehicles. Taking Fuzhou urban cycle as an example, the main driving cycle data was collected, the planned road sections were matched with the driving cycle data to predict the vehicle driving time and energy consumption, and the impedance cost of each objective was calculated by combining the waiting time for charging. The results show that the proposed charging path planning strategy may respectively plan the optimal charging path considering time, energy consumption and comprehensive optimization according to the needs of drivers.
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    Analysis of Cavitation Characteristics for Orifice Plates
    YU Kexin1;SHANG Qunli1;WU Xin2
    China Mechanical Engineering    DOI: 10.3969/j.issn.1004-132X.2021.03.006
    Accepted: 07 February 2021

    Design Calculation and Performance Analysis of Elliptical Corner-filleted Hybrid Flexure Hinges#br#
    WANG Chuanli, LI Cheng, HE Tao, CHEN Guoyu,
    China Mechanical Engineering    2021, 32 (09): 1017-1026.   DOI: 10.3969/j.issn.1004-132X.2021.09.002
    Abstract124)      PDF (6655KB)(87)       Save
     In order to meet the large compliance requirements of compliant mechanisms, a new type of elliptical corner-filleted flexure hinge was designed. Firstly, the formulas of compliance and rotation accuracy were derived on the basis of the Castiglianos second theorem. Under the limit condition of parameters, the structure of elliptical corner-filleted evolved into three other hinge forms: right circular corner-filleted, elliptical right circular and right circular flexure hinge. The calculation formulas of compliance and rotation accuracy of various flexure hinges were combined in a set of equations. The correctness of the calculation formula was verified by the finite element analysis. Secondly, the influence trend of structural parameters on compliance, rotation accuracy and compliance accuracy ratio was discussed. The analysis results show that compliance and rotation accuracy have the opposite trend with the change of parameters, and reducing the minimum thickness is the best way to improve compliance. Then, the performances of four kinds of flexure hinges were compared. The results show that the elliptical corner-filleted hybrid flexure hinge has the maximum compliance but low rotation accuracy, while the right circular flexure hinge has the high rotation accuracy and superior comprehensive performance, but the minimum compliance. Finally, the examples of the elliptical corner-filleted and the right circular flexure hinge were applied and analyzed. The analysis results show that the novel flexure hinge has significant advantages in rotation range and stress level.
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    Reaserch on Anti-rollover Model Predictive Control of Counterbalanced Forklift Trucks
    XIA Guang, LI Jiacheng, TANG Xiwen, ZHANG Yang, CHEN Wuwei
    China Mechanical Engineering    2021, 32 (08): 987-996.   DOI: 10.3969/j.issn.1004-132X.2021.08.013
    Abstract123)      PDF (9299KB)(59)       Save
    In order to reduce the probability of forklift rollover when turning at high speed, a hydraulic support cylinder was designed as actuator to provide lateral support force for the forklift truck. Aiming at the problems of judging the safe region of forklift truck in the driving processes, the dividing strategy of forklift driving states was proposed based on zero moment point. Taking the relationships between lateral component of zero moment point and forklift support plane as dividing basis, and considering the change of forklift support plane in rollover processes, the forklift rollover processes were divided into 3 stages of safe run, danger controllable and critical rollover. In safe run stages, the cylinder didnt provide support force. In danger controllable stages, the model predictive control algorithm was used to adjust cylinder support force and forklift attitude. In critical rollover stages, the cylinder was controlled to provide the maximum support force for the body. This method took a 3-DOF forklift truck roll model as control object and as the basis of zero moment point calculation. Then an anti-roll controller was built in Matlab/Simulink to simulate under European standard working conditions and real vehicle tests were carried out. Therefore, the validity of the anti-rollover model predictive control was verified.
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    Experimental Research of CFRP Cutting by Using Water Jet Guided Laser Processing#br#
    WANG Jianxin, WU Yaowen, ZHANG Guangyi, CHAO Yang, ZHANG Wenwu,
    China Mechanical Engineering    2021, 32 (13): 1608-1616.   DOI: 10.3969/j.issn.1004-132X.2021.13.013
    Abstract120)      PDF (9818KB)(57)       Save
     The key processing parameters of water jet guided laser cutting CFRP were studied by orthogonal test method, the effects of feed rate, water jet velocity, pulse frequency and laser power on cutting CFRP were obtained, and the optimal parameters obtained by direct comparison method and range analysis method were compared for single grooving cutting. The results show that when cutting CFRP under the optimal parameters obtained by range analysis method, the kerf depth increases by 3.2%, the kerf width decreases by 9.2%, the kerf taper decreases by 11.8%, and the line roughness decreases by 40.2%. Compared with the dry laser processing method, it is found that the water jet guided laser processing technology has obvious advantages in cutting CFRP. Due to the scouring and cooling effects of water jet, there is almost no heat affected zone and fiber pull-out on the cutting surfaces of the materials. In addition, the optimal processing parameters were obtained by orthogonal test, and the taper-free cutting of 4 mm thick CFRP was realized by using these parameters.
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