In order to accurately reveal the spatio-temporal evolution mechanism of the flow field of the hydraulic torque converter, five different Large Eddy Simulation models (SL, WALE, WMLES, WMLES S-Omega, KET) were used to simulate the three-dimensional flow field of hydraulic torque converter under braking conditions based on computational fluid dynamics theory. It identified and extracted the unsteady multiscale three-dimensional vortex structure inside the turbine, and then analyzed the characteristics of spatiotemporal multiscale vortex evolution and its influence laws on the evolution of flow field structure. Based on Particle Image Velocimetry (PIV) technology, dynamic real-time calibration method was used to measure the flow field inside the turbine of hydraulic torque converter. Based on the velocity and vorticity information extracted from the post processing, the simulation results of large eddy simulation were compared and the simulation applicability of five subgrid-scale turbulence models was analyzed. The results show that under braking conditions, the multiscale eddy simulation results of SL and WMLES models for the main flow area of the turbine channel are similar, the flow velocity ranges from 0.32m/s to 0.85m/s and the vorticity ranges from 250.77s-1 to 792.95s-1; for the turbine blade pressure surface near the wall high velocity area, the simulation results of WMLES model meet the PIV test results, the flow velocity ranges from 3.7m/s to 4.4m/s, while WMLES S-omega model is better for the simulation of vorticity field is better and the vorticity is 526.47s-1. From the perspective of three-dimensional vortex simulation, WMLES and WMLES S-omega models have more abundant numerical simulation results of three-dimensional vortex near the suction surface of blades, and they are more accurate in capturing small-scale vortex structures near the wall of blades. The KET model simulation results reproduce the obvious vortex shedding phenomenon at the turbine blade outlet, while other models are not accurate enough to identify the structure of three-dimensional vortex. The research results can provide theoretical guidance for high precision numerical simulation of hydraulic torque converter.

Proposed in this paper is a state-constrained synchronous control strategy based on disturbance observer for the multi-cylinder synchronous pulling process of hydraulic support group. First, The relationship among multiple cylinders is analyzed. Next, based on the theory of equal control, a disturbance observer is designed for each subsystem to estimate and compensate the uncertainties and external disturbances of the system. Then, the maximum errors of the systems position and velocity are limited by using the barrier Lyapunov theory, and the dynamic surface theory is introduced to avoid differential explosion in backstepping design and simplify the design of the controller. Moreover, ZY3200/08/18D electro-hydraulic control hydraulic support is used as a model to carry out simu-lation analysis in Simulink, and, finally, a simulation test platform is built for verification. Simulation and experiment results show that the proposed control strategy is of higher trajectory tracking accuracy and synchronization accuracy.

This paper proposes a rigid differential steering of articulated vehicle by taking advantage of hub motor characteristic of distributed-drive articulated vehicle, and constructs an electro-hydraulic hybrid steering mode with hydraulic steering as the main and with differential steering as the auxiliary. The differential steering dynamic model of articulated vehicle is established to reveal the relationship between cornering resistance and differential torque, and, by taking the differential torque acting on the front body of articulated vehicle as an example, the torque distribution method of each wheel torque is investigated and used to formulate the control strategy of hybrid steering system. Moreover, the articulated vehicle is simulated along the single lane changing path, and the energy consumptions are evaluated and compared for the hydraulic steering system and the motor with and without differential steering. Simulation results show that the electro-hydraulic hybrid steering mode can realize the effective energy saving of articulated vehicle under different load and speed conditions.

Based on the fitting relationship between residual compressive stress and overlap ratio, the laser spot path was designed under non-uniform overlap ratio. A laser shock peening finite element (FE) model for laser shock peening damaged 7075 aluminum alloy component was established based on ABAQUS software. The non-uniform overlap ratio laser shock peening simulation was realized and the distribution of residual stress was obtained. The results show that the non-uniform overlap ratio laser shock peening can keep the surface of the specimen in a state of uniform stress after grinding or under tensile load. By increasing the overlap ratio to control residual stress, the surface of the repaired component can be kept in a state of uniform compressive stress under tensile load, so as to inhibit the initiation and propagation of fatigue cracks. The experimental results are consistent with the simulation results, which verifies the reliability of the model.

Based on the lubrication mechanics and the friction principle of asperity, a mathematical model describing the synchronization process of multi-cone friction pair is established and numerically solved. Then, the change laws of the relative speed of the driving and driven plates, the thickness of the oil film, the bearing capacity of the oil film, the bearing capacity of the micro peak, the viscous shear torque, the rough friction torque, etc., with the synchronization time during the synchronization process, are analyzed. Moreover, the effects of such factors as the cone angle, the number of friction cones, the surface roughness, the initial relative speed and the loading pressure on the synchronization process are investigated based on the established mathematical model. The results show that (1) the multi-cone friction pair has an obvious wedge-shaped self-energizing effect and can provide large cone contact pressure with small axial loading force| (2) the synchronous torque can be increased and the synchronization time can be shortened by reducing the cone angle and by increasing the number of friction cones, the surface roughness and the axial loading force| and (3) the synchronization time is roughly linear to the initial relative speed.

In order to study the response characteristics of the scissor-type deployable element under vibration conditions, the study used the ship rust removal device as the vibration source and firstly established the mechanical model of the scissor-type deployable element. And the reliability of the element members under extreme conditions was studied. Then it used numerical modal analysis method and dynamic stress test analysis method under random vibration to study the random excitation problem and response of the scissor expandable unit under vibration conditions. It proposed a method to eliminate the second-order transverse bending vibration and excitation resonance of the scissor expandable unit and carried out dynamic stress simulation for each structural optimization scheme. The results show that the second-order modal vibration (306.15Hz) of the scissor-type deployable unit and the random excitation resonance generated by rust removal are the main reasons for the vibration fatigue of the scissor-type deployable unit. The dynamic stress level of the unit can be reduced most significantly by increasing the thickness of the upper worktable from 10mm to 14mm, reducing the rigidity of the worktable from 20GPa to 19.5GPa, and adding a connecting shaft between the two connecting rods. The research results can provide a theoretical basis for the stable and reliable operation of the scissor deployable unit in engineering applications.

In view of the scheduling problem of die electrode in CNC and EDM stages, a mathematical model with batch processing and correlation characteristics was established. To minimize the tardiness of die parts, the solving process of die electrode scheduling problem was divided into two stages: batch processing and batch scheduling. In the first stage, the batch processing problem was solved according to the principle of correlation, and the correlation priority batch algorithm was designed. In the second stage, the batch scheduling problem was solved by genetic algorithm, and a strategy based on animal breeding was proposed to improve the traditional genetic algorithm. The die electrode scheduling program was developed based on MATLAB software to realize the above two stages of solving process, and the test was carried out under 24 kinds of simulation examples. The results show that, the designed die electrode scheduling algorithm is effective for solving the batch processing and batch scheduling problem of die electrode; the proposed strategy of breeding can significantly improve the quality of traditional genetic algorithm solution; and the tardiness of die parts in the examples can be reduced by 16.71% at most.

In view of the difficulties in the prediction and measurement of machining gap temperature distribution in the process of electrochemical machining (ECM), this paper established and analyzed a temperature multiphy-sics coupling model for profile ECM. The turbulence models of SA, k-ε, k-ω, SST and low-Reynolds-number k-ω were used to calculate the flow field distribution, and the temperature distribution was obtained by coupling electrical field, flow field and temperature field. The simulated value was compared with the experimental value. Results show that the near-wall region flow field solution accuracy of the low-Reynolds-number wall treatment is higher than that of the wall-function and the temperature in the ECM gap can reach a quasi-stable state in a relatively short time. The calculated temperature values based on SST and low-Reynolds-number k-ω models are very close to each other, and the simulated temperature values of the model coupled with the bubble rate are closer to the experimental values.

By taking the propane spherical storage tank of a petrochemical enterprise as the research object, this paper fully takes into consideration the geometric integrity of the tank and the unevenness of wind load distribution at the ANSYS Workbench platform to conduct a fluid-solid coupling analysis. Firstly, a three-dimension numerical simulation of the external air flow field of the tank is performed to obtain the flow field distribution of the surrounding flow. Then, the calculation results of the flow filed are loaded on the outer surface of the tank to perform a structural static analysis. The results indicate that (1) when the wind flows around the spherical storage tank, the velocity first increases and then decreases, forming several vortexes on the leeward side of the spherical shell and the pillar, and the position of flow separation is delayed as the wind speed increases; (2) the wind forms a positive pressure zone on the windward side of the spherical storage tank and a negative pressure zone on the non-windward side; (3) the wind pressure on the windward side of the spherical shell symmetrically distributes in concentric circles, and gradually decreases from the center to the edge; and (4) the stress of the spherical storage tank under wind load is significantly larger than that under the design conditions. According to the results of stress linearization analysis and strength check, there comes to the conclusion that the spherical storage tank meets the standard requirements well. 

This study carried out digital modeling, simulation and verification analysis on the piston pump which is the key hydraulic component of concrete pump truck system. Based on the analysis of its motion law and working principle, it took the swash plate axial piston pump with conical cylinder blocks as the research object, and characterized the kinematic characteristics and flow characteristics of the piston with the method of space geometry and established a variable pump plunger model with AMESim simulation software. Based on the analysis of constant power control, constant pressure compensator control and electro-hydraulic proportional control variable displacement principle of variable pump, etc., this study established a power-pressure-electro-hydraulic proportional compound controlled variable pump AMESim simulation digital model including sub-models such as the pump body piston model, valve plate model, sliding shoe model, variable mechanism model, etc. The outlet flow characteristics, pressure displacement characteristics, current displacement characteristics and transient response characteristics of the plunger pump were studied through the coordinated control of control of the swash plate inclination angle, motor speed, system load and control current. The research results show that the simulation characteristic curve obtained by using the established hydraulic pump digital model is in good agreement with the test results, and the maximum relative errors of the pressure displacement characteristic and current displacement characteristic prediction are 6.31% and 7.73%, respectively. Thus it verifies the accuracy of the model and provides model supports for digital twins and performance optimization upgrades of construction machinery.

In order to overcome the difficult acquisition of feature points and the low accuracy of ORB-SLAM algorithm in large-scene and weak-texture environment, a PAL-SLAM algorithm based on RGB-D camera is proposed. In this algorithm, first, on the basis of ORB-SLAM algorithm, a new framework of point-line feature fusion is designed. Next, by investigating the fusion principle of point feature and line feature, a re-projection error model of point-line fusion is deduced, and the Jacobian matrix analytical form of the model is obtained. Then, the PAL-SLAM algorithm framework of point-line feature fusion is proposed. Furthermore, a comparative experiment between PAL-SLAM algorithm and ORB-SLAM algorithm is carried out by using TUM data set. The results show that the positioning accuracy of PAL-SLAM algorithm is higher in large indoor scenes, and the standard error is far less than that of ORB-SLAM algorithm, which is only 18.9% of that of ORB-SLAM algorithm| and that PAL-SLAM algorithm reduces the positioning error of traditional visual SLAM algorithm in large-scene and weak-texture environment, and effectively improves the accuracy of the system. Moreover, the experimental results at a platform based on Kinect V2 show that the proposed PAL-SLAM algorithm can be well combined with the hardware platform.

Aiming at the problems of limited analysis and difficult validation on flow characteristics of children upper airway, this paper presents an experimental bench using upper airway models manufactured by 3D printing technology to study these problems. The maximum difference between experimental results and clinical nasal resistance test is 11.1%, which proves the experimental method based on 3D printing technology is reliable and accurate, and it can be a direct and easy method for the research of flow characteristics of children upper airway. After that, the effect of different levels of hypertrophy of tonsil on flow characteristics is studied. It is found that, when the narrow level of oropharynx reaches 56%, where the level of hypertrophy of tonsil reaches III degree, flow characteristics of upper airway will obviously change, in terms of increasing flow velocity and resistance, decreasing flow volume, and a large inverse pressure and pressure difference in oropharynx, which can an explanation of the symptoms for OSAHS child, and also will be a significant reference to clinicians on tonsillectomy operation and its postoperative recovery plan.

Aiming at the complex situation where the parameters of powertrain mounting system (PMS) of electric vehicle are both uncertain and correlated, this paper investigated the inherent characteristics of electric vehicle PMS considering the correlation of probabilistic parameters. Firstly, the correlation matrix and probabilistic parameters were employed to describe the correlation and uncertainty of PMS parameters. Then, the Monte-Carlo method (MCM) was developed to calculate the PMS inherent characteristics with correlated probabilistic parametersbased on Monte-Carlo sampling. Then, an efficient method for calculating the statistical moments of PMS inherent characteristics was put forward based on sparse grid numerical integration (SGNI). Finally, the effectiveness of the proposed approach was demonstrated by the numerical example of an electric vehicle PMS. The analysis results show that, the SGNI method has good accuracy and efficiency in solving statistical moments and bounds of PMS natural frequencies and decoupling ratios, compared with MCM. The correlation of probabilistic parameters has a great influence on the upper and lower bounds of decoupling ratios. More reasonable analysis results can be obtained by taking the correlation of the probabilistic parameters into consideration. 

Regular feed pushing is an important link in the feeding process of dairy cows, and the intelligent feeding assistance of robot instead of human is becoming the development direction in the future. The feeding robot can complete multiple feeding throughout the day, which is widely used in the feeding of dairy cows in large and medium-sized pastures. However, the existing feeding robot has a single function, which can only complete the uniform feeding function, and can not meet the personalized feeding needs of cattle. To solve this problem, this paper proposes an intelligent pushing method of feeding assistant robot. The QR code label is introduced as the positioning label of cow neck rail, and the detection frame area of QR code label and cow head is obtained based on YOLOv4 deep learning model. The detection frame area of QR code label is recognized and tracked in real time through preprocessing and prediction algorithm, and the QR code label and cow head are matched to determine the position of feeding neck rail; According to the position matching information of cow-code and the residual forage distribution information, the robot push plate was controlled to change the pushing angle to realize personalized pushing and meet the individual feeding needs of dairy cows. Research and test results show that the proposed intelligent push method has a recognition rate of 96% for the QR code; In the case of losing 60 consecutive frames, the tracking and prediction accuracy of the QR code is less than ± 2.85%; The processing time of each frame in GPU is 34.4 ms; The accuracy of intelligent feeding is 100%, which can meet the real-time requirements of intelligent pushing in complex environment.

Based on the average flow equation and the Ng-Pan turbulence model, using the boundary condition of mass conserving (JFO), a mixed lubrication model considering wear and turbulence was established. A finite difference method was used to solve the model. Under the condition of constant external load, the effects of wear and turbulence on oil film pressure, oil film thickness and friction coefficient were studied. The results show that wear significantly changes the oil film pressure and oil film thickness distribution, and has an important influence on the Stribeck curve of bearing. Under high-speed operating condition, turbulence reduces the maximum oil film pressure of the bearing, and increases the minimum oil film thickness, cavitation zone, and friction coefficient. Wear and turbulence have a critical impact on the lubrication performance of the bearing, and the two together determine the lubrication performance of the bearing.

The scaling effect of specific cutting energy is one of the most challenging problems in metal cutting. There is no consensus reached on the mechanism of the scaling effect, and the contribution of the cutting temperature on the scaling effect was rarely studied. Here the orthogonal cutting experiments under different initial temperature were conducted. It shows significant dependence of the scaling effect phenomenon on the temperature effect. The scaling effect phenomenon becomes more obvious at lower initial temperature. The finite element model of orthogonal cutting was further developed to study the contribution of temperature on the scaling effect. The results show that, there exists two temperature gradient zones near the ends of the primary shear zone along the shear direction. The length of the gradient zones are independent on the uncut chip thickness. The existence of the temperature gradient zones causes the average temperature in the primary shear zone to drop with decreased uncut chip thickness, which gives rise to the increase of flow stress, leading to the nonlinear increase of the specific cutting energy.

The working device of the excavator is a large welded structure, which is prone to damage at the weld due to various complex loads during the operation, and its fatigue strength is directly related to the service life and performance of the whole machine. In order to evaluate the fatigue life of its welds more effectively, an evaluation method of weld fatigue life of excavator working device was proposed based on the equivalent stress method in this paper. That is, based on the node force and node moment on the welding line, the structural stress that is not sensitive to the grid is calculated. The fatigue life is evaluated by the fatigue cumulative damage criterion and the main S-N curve of welded joints, which can unify with different joint types, plate thicknesses, and loading modes. By building the finite element models with detail information of the welding seam for the boom and bucket, the fatigue damage assessment was carried out for six key welds on the boom and the bucket by the equivalent structural stress method. The fatigue assessment accuracy of the boom and the bucket is comparatively studied with the fatigue experiment results in this study, the results indicate that the deviations obtained through the nominal stress method are 9.2% and 14.2%, and they reach to 24.4% and 23.4% by employing the hot spot stress method and decrease to 6.6% and 9.5% in the approach with equivalent structural stress analysis. Therefore, compared with the nominal stress method and the hot spot stress method, the evaluation results of the equivalent structural stress method are the closest to the fatigue test results. The evaluation results of the nominal stress method tend to be bold, while the evaluation results of the hot spot stress method tend to be conservative, which means that the equivalent structural stress method is very effective and reliable for the fatigue life assessment of excavator working device. The proposed method can provide ideas for the fatigue life assessment of other welded structures.

In this paper, a certain type water hydraulic axial piston pump was taken as a prototype, and the original smooth surface swash plate was replaced with a biomimetic non-smooth surface one. The flow-pressure, volumetric efficiency-pressure and mechanical efficiency-pressure of the test pump at three different pressures of 7 MPa, 10 MPa, and 12 MPa were tested, and the worn surface of the swash plate was observed using laser confocal microscope and scanning electron microscope. The results show that the slipper pair with non-smooth surface can produce hydrodynamic lubrication effect and have chip holding capacity due to pits. Self-lubrication can be realized during the friction process, achieving the effect of reducing drag and wear. With the increase of working pressure, friction marks in the half-circle high pressure area of the non-smooth surface swash plate are gradually obvious, grooves on the worn surface become wider and deeper, and adhesion wear and oxidation wear are aggravated. That is the friction and wear are aggravated. The volumetric efficiency, mechanical efficiency and total efficiency of the non-smooth surface slipper pair test pump are increased by 0.2%-0.6%, 0.1%-1.7% and 0.1%-2.3% respectively, compared with those of the smooth surface slipper pair test pump.

To solve the problem of the low success rate of robot vision grasping using fixed environment camera in the scene of cluttered and stacked objects, an eye-hand follow-up camera viewpoint selection policy based on deep reinforcement learning is proposed to improve the accuracy and speed of vision-based grasping. Firstly, a Markov decision process model is constructed for robot active vision-based grasping task, then the problem of viewpoint selection is transformed into a problem of solving the viewpoint value function. A deconvolution network with encoder-decoder structure is used to approximate the viewpoint action value function, and the reinforcement learning is carried out based on the deep Q-network framework. Then, to resolve the problem of sparse reward existing in reinforcement learning, a novel viewpoint experience enhancement algorithm is proposed. The different enhancement methods between the successful and failed grasping process are designed respectively. And the reward region can be expanded from a single point to a circular region for improving the convergence speed of the approximation network. The preliminary experiment is deployed on the simulation platform, and the robot model and the grasping environment are simultaneously built in the simulation platform to implement the offline reinforcement learning. In the process, the proposed viewpoint experience enhancement algorithm can effectively improve the sample utilization rate and speed up the convergence of training. Based on the proposed viewpoint experience enhancement algorithm, the viewpoint action value function approximation network can converge within 2 h. To obtain the results from the verification with application, the proposed viewpoint selection policy is applied to the real-world scenes with robot for grasping experiments. The result shows that the viewpoint optimization based on this policy can effectively promote the accuracy and speed of robot grasping. Compared with the general grasping methods, the proposed viewpoint selection policy needs only one viewpoint selection in real-world robot grasping to find the focus region with high grasping success rate. And the method can also promote the processing efficiency of the best viewpoint selection. The grasping success rate in cluttered scenes is increased by 22.8% against the single-view method, and the mean picks per hour can reach 294 units. As whole, it shows that the proposed policy has the capacity of industrial application.

Hybrid electric vehicle Energy Management Strategy (EMS) optimization is a multi-objective and multi-stage decision-making problem that needs to comprehensively optimize several performance indicators of hybrid electric vehicles. The traditional multi-objective optimization algorithm faces challenges such as low efficiency and difficult to guarantee convergence when dealing with these problems. Combined with the idea of non-dominated sorting algorithm, this paper extended the traditional Dynamic Programming (DP) to the field of multi-objective optimization, and proposed Non-dominated Sorting Dynamic Programming (NSDP). When using this algorithm, the driving condition was divided into several stages firstly. In each stage, the cumulative target value vector generated by the hybrid electric vehicle in different control strategies was obtained, and the current non dominated solution set and the corresponding control strategy were obtained through the non dominated sorting algorithm. Then, the non dominated solution set of each stage was used for reverse iteration in turn, until the leading edge of the non dominated solution set and the corresponding energy management control strategy of the whole driving cycle were obtained. In the simulation experiment, Weighting Dynamic Programming (WDP) and Non-dominated Sorting Dynamic Programming were applied to solve the optimization problem of multi-objective energy management strategy for power split hybrid electric vehicles and series parallel hybrid electric vehicles under constant acceleration conditions. The results show that NSDP not only can effectively complete the solution and ensure convergence, but also has significant advantages in homogeneity of solution set and solving efficiency. Furthermore, NSDP was used to solve the energy management optimization problem of series parallel hybrid electric vehicles running in Worldwide Harmonized Light Duty Vehicle Test Cycle (WLTC). The non dominated solution set can be used to analyze the working characteristics of vehicles and provides a reliable reference for the formulation of actual energy management strategy.

The dragging teaching method is easy to operate and has high teaching efficiency, which is more in line with modern flexible production. To realize the dragging teaching of industrial robots, it is necessary to accurately measure the external force and control the motion caused by the external force. In order to measure the external force exerted by the operator without torque sensor, an external force observer based on disturbance Kalman filter was designed. The observer takes the external joint torque as the disturbance term, and introduces generalized momentum to establish the state space equation of the robot system, and then uses the Kalman filter algorithm to obtain the optimal observed value of the external torque. Among them, in order to improve the estimation accuracy, the robot dynamic model was established by combining the rigid-body dynamic model and a deep neural network, which not only avoids modeling the complex friction torque but also compensates for the unmodeled factors through the deep neural network. Besides, in order to realize the leading control of the robot in the process of dragging teaching, the dynamic response relationship between the teaching motion and the external torque is equivalent to a mass damping system. An admittance control method with adaptive damping was proposed to convert the observed external torque into the desired joint angle of the teaching motion, and adaptively adjust the system damping parameters according to the change trend of the external torque to improve the teaching effect of the robot. The experiment results show that the proposed dynamic model has a lower mean square root error in the prediction torque, which can reduce the error by no less than 20%. The proposed control scheme can realize the dragging teaching without torque sensors on the six-degree-of-freedom industrial robot, and the adaptive damping method can reduce the torque required to rotate the joint by about 19%, which is more conducive to the start and stop of the teaching motion.