Ball screw is a key transmission component in electro-hydraulic servo equipment, and its structural design will have a direct impact on the mechanical properties and further affect the stability and life of its transmission. The system was analyzed by ABAQUS solver to study the ball load carrying situation and the influence of nut structure on its load. The results show that the secondary development of ABAQUS based on Python can realize the whole process of finite element parametric modeling and static analysis of ballscrew sub-systems, which provides data and methods for the subsequent study of the optimization of the structural design of the nut returner and the selection of materials.

In order to improve the efficiency of automatic fruit picking, deeply implement the concept of technology strengthening agriculture and smart agriculture, taking tomato picking as an example, a two axis harvesting robotic arm is designed according to the functional requirements of tomato fruit picking process and the structural characteristics of human arms, using ANSYS Workbench software to optimize its structure. The end effector is designed as a flexible pneumatic driven robotic arm, building a robotic arm and simulating its motion posture in the RobotStudio, finally, the camera, a key component of the visual system of the tomato picking robot, is set up and programmed for control. The construction of an automatic recognition tomato picking robotic arm control system has been completed.

This paper based on hydraulic landing gear test bed, combined hydraulic system, landing gear system, landing gear structure to carry out comprehensive test. Study on the working characteristics of an aircraft landing gear retraction system. Obtain the influence of hydraulic system output flow rate and switch control logic on the landing gear retraction and retraction characteristics. Meanwhile, the typical fault of landing gear down and hard unlocked during system test is analyzed. It is determined that the landing gear is hard unlocked due to back pressure on the lowering pipeline during the lift action when lowering the landing gear. Through the comparative analysis of theoretical research and experimental results, accurately locate the position where fault occurred, further deepen the understanding of the system.

Focus on hydraulic pressure fluctuations in traditional accumulators during energy storage and release, a spring-based constant pressure accumulator is proposed. The operational principle of the accumulator is analyzed, with the profile curve equation for the critical component derived and solved. Key parameters for an accumulator in a specific hydraulic system are designed. A simulation model is constructed in ADAMS software to test the performance of the accumulator under varying flow conditions. It achieved a force deviation below 1% during stable operation, serving as a reference for the design of hydraulic energy storage systems.

A detailed model for a rotationally balanced constant-pressure dual-row axial piston pump was meticulously developed, followed by an extensive AMESim simulation. This simulation investigated how outlet pressure impacts flow, the correlation between outlet pressure and the distribution plate's rotation angle, and the pump's dynamic behavior with sudden changes in the variable orifice signal. The analysis considered the nuanced effects of reset spring stiffness in the variable mechanism and valve stiffness in the pressure control valve. The findings highlighted a decrease in outlet flow with rising outlet pressure and an increased rotation angle of the distribution plate. A stiffer reset spring led to quicker dynamic response and reduced overshoot in the pump. Conversely, a larger valve core diameter slowed down the pump's dynamic response, prolonged steady-state attainment, and intensified flow and pressure oscillations by amplifying the distribution plate's rotation during that phase.

Pneumatic valves are common pneumatic components that play a role in changing the direction of the airflow within the pneumatic system and are widely used in automated equipment, commercial vehicles, and medical devices. One important performance index of the pneumatic valve is flow rate. This paper takes a two position four-way solenoid valve as an example to carry out the design calculations for flow rate, structural calculations, flow simulation, and experimental verification, summarizing a general design process for the flow rate of pneumatic valves.

In hydraulic fluid transmission systems, ISO 6149 inner cone sealing structure is widely used because of its good sealing effect, but this sealing structure has some shortcomings, such as cone hole is difficult to process, easy to cut the seal ring during installation, so a new sealing structure design method is proposed in this paper, through the comparison of ISO 6149 inner cone sealing structure, the sealing principle, characteristics and advantages of this type of sealing structure and method to determine the sealing parameters is given, the application is verified by practical application and simulation.

The square hole filter is a typical pollution control component in aviation fuel systems, which is prone to blockage and other problems, seriously affecting the reliability of the filter and system. This article uses fluid simulation software to establish a simplified model of square hole filter screen. The CFD-DEM coupling method is used to study the filtration process of square hole filter screen components, and the influence of oil cleanliness and filter screen accuracy on filtration efficiency is analyzed. The results show that in the early stage of filter filtration, the main focus is on surface medium filtration, and the particle group smaller than the mesh size is the key to interception in the middle stage of filter filtration. The particle concentration and filter accuracy have a significant impact on the filtration efficiency of the filter. The higher the particle concentration, the lower the particle filtration efficiency; There are significant differences in the filtration efficiency of the same particles when passing through different specifications of filters. The smaller the filter size, the lower the filtration speed, the higher the filtration efficiency, and the more particles are intercepted. Under the condition of ensuring filtration performance, the accuracy of selecting filter specifications can be improved by one level.

To select the appropriate materials for the butterfly plate and valve seat to ensure the strength and sealing performance of the triple-eccentric butterfly valve, the effects of three different materials on the strength and sealing performance of the triple-eccentric butterfly valve were studied by simulation. The results show that for GH4169, aluminum bronze and polytrifluorochloroethylene seats, the sealing pressure distribution of the triple eccentric butterfly valve is uneven, and there is a low sealing pressure area near the valve shaft. The suitable materials of the butterfly plate and seat can increase the sealing pressure in the low sealing pressure area, and improve the strength and sealing reliability of the three-eccentric butterfly valve. The sealing specific pressure ratio of the aluminum bronze seat is about 2 times of that of the GH4169 seat, which has good strength and sealing performance.

As a new type of volumetric pressure pump, spherical pump has the advantages of tiny volume, high power density, compact structure, and high reliability, which has strong potential against traditional hydraulic components in miniature hydraulic drive field. Currently, there is little research on spherical pumps, and there are problems such as incomplete theoretical foundations and modeling research, which to a certain extent hinder the full realization of the advantages of spherical pumps. Therefore, it is necessary to improve the theoretical and modeling foundation of spherical pump systems, and build a relatively universal kinematic analysis method for spherical pumps to provide theoretical support for the structural design optimization and promotion of spherical pumps. Based on the unique volume theory of spherical pumps, the structure and working principles of existing two configurations (A/B type) spherical pumps are analyzed, and mathematical motion models are established, which constructs the mapping relationship between kinematic characteristics and structural parameters. Then a comparative analysis is conducted between the A/B type, and through modeling and simulation, the accuracy of theoretical analysis is verified. By reversing the transmission chain, a new type of spherical pump with improved structure has been designed, which can reduce the number of precision spherical fits, improve processability, and achieve precise flow distribution in spherical pump.

This article conducted experimental tests on the sealing performance, opening characteristics, and static characteristics of a prototype of a large flow plug-in hydraulic control one-way valve. By applying simulation technology, the flow field characteristics of the plug-in hydraulic control one-way valve port at different valve sleeve cone angles were calculated and analyzed, and the calculation results of the prototype model were compared and analyzed with the experimental test results. It is concluded that different valve sleeve cone angles have a significant impact on the flow field characteristics of the valve port of the plug-in hydraulic control one-way valve. Reasonable selection of valve sleeve cone angles can reduce pressure loss at the valve port, reduce the probability of valve port cavitation and noise generation, increase the stiffness of the valve, stabilize the flow state at the valve port, and improve the performance of the valve. This provides theoretical support for the design of the valve port structure of large flow plug-in hydraulic control one-way valves.

The three-arm drilling jumbo is specialized equipment for hard rock tunnel construction using the drill-and-blast method. Its boom system is crucial for the extensive operational range of the end drill. Addressing the issues of easy vibration and large deformation in the boom system of the three-arm drilling jumbo, this paper proposes optimizing the mechanical structure strength and the first-order resonant frequency of the boom. It develops a high-stability electro-hydraulic drive system for the boom, enhancing the stability and reliability of the boom system of the three-arm drilling jumbo. Firstly, based on the analysis of the stress-strain distribution and modal characteristics of the traditional boom structure, this paper proposes an optimized design for the internal rib structure of the telescopic arm and the external rib structure of the main arm. Without affecting the overall structural dimensions, the maximum deformation of the main arm (with the telescopic arm fully extended) is reduced from 32.1 mm to 19.6 mm, and the first-order natural frequency of the main arm (with the telescopic arm fully extended) is increased from 2.36 Hz to 3.03 Hz. On this basis, a new high-stability electro-hydraulic drive system for the boom is developed. A simulation analysis model of the electro-hydraulic drive system is established, and parameters such as the spring stiffness of the balance valve, the flow area of the damping valve at the control port and oil return port of the balance valve, and the flow area of the damping valve in the main oil circuit are optimized to enhance the stability of the electro-hydraulic system. Through simulation modeling analysis, the influence laws of different hydraulic system parameters on the stability and dynamic characteristics of the boom control system are clarified. This paper proposes that the optimization of the boom's mechanical and hydraulic systems can improve the stability of the boom system, providing an important reference for the future design and debugging of three-arm drilling jumbos.

This paper introduces the structure of dry gas seals and succinctly outlines their characteristics and working principles. with an emphasis on the basic structure of the dry gas seal control system, the selection of the dry gas seal control system, and the pre-treatment of gas and the regulation and control of gas. Additionally, the paper compiles and analyzes potential causes for abnormal instrument data within dry gas seal control systems, as well as the interplay between system malfunctions and seal failures. It also proposes experimental testing methods to address these issues. The findings and insights contribute to the design and maintenance of dry gas seal control systems in industrial applications, ensuring their effective operation and the stable performance of associated equipment. Moreover, the paper offers practical solutions that can be directly applied to on-site operation.

The wave compensation system of offshore trestle can realize the safe and efficient transfer of personnel and materials at sea, and is the key system of large marine operation and maintenance ships. Aiming at the bottleneck problem of high energy consumption in the wave compensation system of offshore trestle, a design scheme of active- passive composite wave compensation electro-hydraulic system for pitching joint of offshore trestle is proposed in this paper. Firstly, this paper analyzes the mechanical structure of the wave compensation system and its working principle of the pitching joint. A passive wave compensation system based on high-pressure gas follow-up support is designed to reduce the energy consumption caused by gravity during the pitching action of offshore trestle. An active wave compensation hydraulic control system based on electro-hydraulic valve group is designed to realize the closed-loop control of pitching motion of offshore trestle. Then, through theoretical modeling and simulation analysis, the mechanism of the designed system to compensate the trestle's dead load is revealed, the energy distribution of the passive compensation system and the active compensation system is analyzed, and the energy consumption characteristics of the designed active-passive composite wave compensation electro-hydraulic system under different passive compensation pressures are explored. Finally, the active-passive composite wave compensation electro-hydraulic system for pitching joint of offshore trestle is developed, and the driving and control capability of the designed system is verified by experiments. The results show that the designed active-passive composite wave compensation electro-hydraulic system can realize the low energy consumption and high precision control of the offshore trestle, which has important strategic significance for the future installation, operation and maintenance of offshore wind power in China.

In order to further improve the overall efficiency of the emulsion pump, research has been conducted in the directions of the transmission system, hydraulic distribution system, and pressure control system for energy loss control measures. The study proposes a transmission method for the emulsion pump without a reduction mechanism and a processing technique for the inner bore of the slide based on meshed flat-top honing. Friction and wear tests are conducted to validate the wear reduction measures of the emulsion pump's crosshead-slide friction pair. The impact relationship between the high-pressure packing seal preload force and leakage is investigated, and experimental validation is performed to determine the preload force with the lowest energy loss. The original pressure control system is replaced with a variable frequency speed-regulated linkage unloading valve to reduce energy loss during the unloading process. The research findings are applied to a 630 L/min, 40 MPa emulsion pump, and industrial tests are conducted underground at the Bayan Obo coal mine. The overall efficiency is increased from the original 87% to 91.5%.

According to the actual engineering requirements that the internal installation space of the weapon launcher is limited, the impact speed of the recoil bar is fast, and it needs to run through the inside of the buffer, an improved new type of gradual hydraulic buffer structure is proposed. The dynamic modeling of the buffer is carried out based on the inclined plate gap flow theory and the oil compressibility theory. The model is solved by Simulink, and the changes of internal piston rod speed, stroke, oil pressure and buffer force are analyzed under different initial speed conditions. An ejection test scheme is designed, and the prototype is tested and verified by this scheme. the test results show that the maximum error of collision energy loss between theory and practice is 9.49%, the maximum error of buffer force is 9.69%, and the maximum error of buffer displacement is 4.67%. The applicability and accuracy of the theoretical model are verified. It provides a design theoretical basis for solving the smooth cushioning of the high-speed recoil bar in the limited space of the weapon launcher.

To reduce the energy consumption of data centers and improve the air flow organization, as well as to solve the hotspot problem, loop type heat pipe backplate air conditioning is gradually being applied in data center renovation. This article tested the compressor-liquid power loop heat pipe backplate air condition system, combined with the concept of annual energy efficiency ratio in GB/T 19413—2010, measured the cooling capacity and total cooling power consumption at various operating points, calculated the annual energy efficiency ratio, and conducted comparative experiments with air-cooled compressor-liquid power loop heat pipe inter row air condition with the same cooling capacity. It can be seen that compressor-liquid power loop heat pipe backplate air conditioning has advantages under the condition of meeting the cooling load of the data center.

Pneumatic shift system is used to reduce the driver's shifting force and improve the vehicle's shifting smoothness, which is an important link to improve vehicle safety. The existing pneumatic shift system has many problems, such as multiple pneumatic failures, poor man-machine coupling and low gear shift control precision. In the process of shifting, it is easy to have the shift stick and dislocation caused by man-machine confrontation, which leads to the shift failure and even leads to serious driving accidents. This paper analyzes the research status of pneumatic shift system fault diagnosis and pneumatic shift control system at home and abroad, and points out the existing problems and future development trends in the fault diagnosis ability of pneumatic shift system, compliance and flexible control of pneumatic shift system, which provides reference for the development of efficient pneumatic shift control system and real-time fault diagnosis technology.

During the vehicle turning process, there are issues of low stability and safety. Therefore, a method for active rear wheel steering of automobiles based on self disturbance rejection hydraulic control technology is proposed. By constructing a vehicle lateral dynamics model and designing a variable hydraulic transmission ratio algorithm based on it, the expected yaw rate of rear wheel steering can be accurately calculated; Using the expected yaw rate as the tracking target, design an active disturbance rejection hydraulic controller that includes an extended state observer, tracking differentiator, and nonlinear error hydraulic control law; By obtaining additional rear wheel steering angles and adjusting them, ensure that the car can closely follow the ideal model and achieve precise control of rear wheel steering. The simulation results show that by tracking the vehicle's center of mass sideslip angle and yaw rate, and applying hydraulic transmission ratio, the vehicle's stability is significantly improved, effectively preventing the risk of rollover and ensuring driving safety. At the same time, this control method enables the vehicle to exhibit excellent yaw rate response characteristics, and the estimated value of the center of mass lateral deviation angle is highly accurate, which is of great significance for improving the vehicle's steering performance and driving safety.

The C-shaped sealing ring is the core component that ensures the sealing of the pressure vessel in nuclear power plants, and its sealing performance is directly related to the safe and stable operation of nuclear power plants. At present, the commonly used C-shaped ring in nuclear power plants is a sealed layer coated with silver. However, the usage temperature of the silver coated C-shaped ring is generally limited to below 400 ℃. For a new type of high-temperature nuclear power unit reactor pressure vessel with a design temperature of up to 550 ℃ and multiple cold and hot temperature cycling conditions, this paper introduces the main structural materials, manufacturing process, and technical key of a new type of nickel coated C-shaped ring, and conducts various cold and hot comprehensive performance tests on the new nickel coated C-shaped sealed sample ring at room temperature and high temperature. The experimental results show that the leakage rate of the new nickel coated high-temperature C-shaped sealing ring studied can reach ≤5.0×10^-6 Pa·m³/s at a high temperature of 550 ℃, which can be used for the engineering application of metal static sealing rings at 550 ℃ in nuclear power plants and other engineering fields.

Taking the mechanical seal used in the ultra-low temperature liquid oxygen pump of a certain air separation unit as the research object, a simulation test system for ultra-low temperature mechanical seal was established. The simulation test was carried out using liquid nitrogen as the test medium, and the variation law of blowing nitrogen temperature and acoustic emission signal was studied. During the sealing start stop process, there was solid impact between the sealing end faces, and there was no solid impact during stable operation. The sealing end faces were in non-contact operation. During the start-up process, the fluid dynamic pressure effect between the sealing end faces is insufficient to form a complete fluid film, and there is micro convex contact. The acoustic emission signal rapidly increases and peaks appear. As the speed increases, the fluid dynamic pressure effect on the sealing end faces increases, and the acoustic emission signal gradually decreases until the sealing operation stabilizes and the acoustic emission signal tends to stabilize. During the shutdown process, as the rotational speed decreases, the shear effect of the fluid film decreases, and the acoustic emission signal first shows a slight decrease. Later, as the rotational speed continues to decrease, the fluid dynamic pressure effect is insufficient to form a complete fluid film, and the acoustic emission signal rapidly increases and peaks. The temperature of the nitrogen gas blown during the entire experiment was between 10.7 ℃ and 22.5 ℃, and the sealing design was reasonable, meeting the requirements for on-site use of the equipment.

The mining technology in China's coal industry is constantly upgrading, and the development of large mining height hydraulic supports is also rapidly increasing. The requirements for the strength characteristics of hydraulic supports to resist impact ground pressure have significantly increased. The safety valve is a key component of hydraulic support to resist impact and plays a role in overload protection. Therefore, analyzing the dynamic characteristics of safety valves is crucial for ensuring safe coal mining. In response to the problem of slow response speed in existing pilot operated safety valves, this paper proposes a dual variable throttling port controlled pilot safety valve using the A-type hydraulic half bridge principle. Based on its structure and working principle, a hydraulic support unloading circuit model with the safety valve was built in AMESim software. Simulation results showed that the pressure rise time of the safety valve was 2 ms, the steady-state overflow pressure was 49 MPa, the pressure overshoot rate was 29.5%, the flow rate was 1172 L/min, and the unloading time was 19 ms. In the hydraulic support unloading circuit model, the influence of adjusting the height of the hydraulic support column extension and the dynamic load impact force on the unloading characteristics of the safety valve is further analyzed.

Aiming at the issue of lubricating property in the slipper pairs of axial piston pumps, micro textures are arranged on the surface of the sliding shoes textured surface slipper pairs of axial piston pumps, an orthogonal experimental scheme was adopted to simulate and study the effects of operating parameters (film thickness, speed), surface texture shape parameters (pit shape, diameter, depth to diameter ratio), and area ratio on the surface bearing capacity of the slipper pairs. The results showed that the primary and secondary order of the multiple influencing factors was speed, area ratio, pit shape, diameter, depth to diameter ratio, and film thickness. The optimal combination of multiple factors was speed 1500 r/min, area ratio 20%, spherical shape, diameter 500 μm, depth to diameter ratio 0.4, and film thickness 20 μm; Based on pressure and velocity cloud maps, the fluid dynamic lubrication effect of textured surfaces and the mechanism of improving surface bearing capacity were analyzed. On the basis of the optimal combination, the impact of single factor changes on bearing capacity was analyzed.

The pump turbine of a pumped storage power station in China was used as a model for research, and according to its “S” characteristics, the movable guide vane airfoil was changed and assembled in the original water guide mechanism with different arrangement methods, and the influence of the change of the movable guide vane airfoil on the “S” characteristics of the pump turbine and the influence of the guide vane force characteristics were analyzed through numerical simulation based on the SST k-ω model. The results show that changing the airfoil of the guide vanes can effectively destroy the high-speed water ring between the active guide vanes and the impeller, reduce the obstruction of fluid flow into the impeller, and improve the flow state in the impeller area, and at the same time, the change of the movable guide vane airfoil also improves the radial force of the guide vane, and the peak-to-valley difference of the radial force becomes smaller after adding the modified movable guide vane, which has a good impact on the operation stability of the unit.

In the semi-outboard hydraulic system, compensating the return oil pressure is an important method to reduce the seawater infiltration into the system and improve its reliability. In this paper, a new type of oil return pressure compensator for deep-sea semi-outboard hydraulic system is presented, and its working principle is described. Through the analysis and mathematical modeling of its working process, the structural parameter design of each key part is introduced in detail. The test results show that the deep-sea adaptive pressure compensator can realize continuous pressure compensation under different states of the hydraulic system, and the maintenance pressure is always greater than the external marine environment pressure.

At present, the assembly of the servo mechanism supporting the joint bearing is mainly completed by manual press, which needs to test the proficiency of the operator, and increase dependence on the operator. The assembly efficiency is low, and the assembly quality consistency cannot be guaranteed. In order to improve the production efficiency and automatic production degree of workshop, in this paper, a bearing pressing method with automatic loading and unloading is proposed. By relying on the bearing pressing equipment with automatic loading and unloading of the bearing, the traditional assembly method relying on the press is optimized. Firstly, the whole structure is designed, and the working principle is introduced. Secondly, the key links are studied and the key parts are checked. Finally, the pneumatic circuit and the electrical control part of the equipment are introduced. In this paper, the technology method is proposed, which is of great significance to improve the production efficiency of workshop bearing assembly and improve the consistency of product quality.

On January 8, 2025, Professor KONG Xiangdong from Yanshan University was invited to give a presentation titled “Conservation and Breakthrough Integration of Technological and Industrial Innovation Advancing Hydraulic Components and Systems Toward High-end, Intelligent, and Green Development” at the “2025 Welcome Spring Festival Seminar of China Hydraulics Pneumatics & Seals Association” held in Beijing. Professor KONG Xiangdong analyzed the development advantages, bottlenecks, and prospects of hydraulics pneumatics & seals industry in the transformation towards high-end, intelligent, and green (three modernizations). Starting from the theoretical core of “Conservation and Breakthrough” and “Integration of Technological and Industrial Innovation”, he emphasized that the industry needs to consolidate the foundation of theory and process inheritance with “Conservation”, promote high-level technological self-reliance and self-improvement in the field of hydraulics pneumatics & seals with “Breakthrough”, and drive the high-end, intelligent, and green development of hydraulics pneumatics & seals industry through “Integration of Technological and Industrial Innovation”. The report also combines the exploration and practice of the hydraulic major and its research team at Yanshan University on the path of “Three Modernizations” development, and introduces a series of practical measures such as talent cultivation, diversified integration development, and technological innovation and transformation of the research team in the hydraulic engineering major at Yanshan University, to help solve the “Three Modernizations” development problems in hydraulics pneumatics & seals industry. This article is compiled from on-site reports and provides a theoretical framework and practical inspiration for the development of the “Three Modernizations” in hydraulics pneumatics & seals industry.

In view of the pressure pulsation characteristics of the axial piston pump, this paper introduces the working principle of the axial piston pump, carries out kinematics analysis, deduces the calculation formula of the actual output flow of the piston pump, and obtains the factors that may affect the output flow of the piston pump. AMESim is used to simulate the pressure pulsation of the piston pump under different speed, swash plate angle, cavity volume, user flow and internal leakage flow, and analyze the influence of each parameter on the outlet pressure, pressure pulsation amplitude and frequency. The simulation results are compared with the pressure pulsation test data of a certain hydraulic pump, and the simulation results are similar with the test data in pressure pulsation characteristics, which provides support for the correctness of the modeling in this paper. This paper has certain reference significance for the selection of working parameters of axial piston pump and the simulation/test of pressure pulsation of piston pump.

Due to the complex working conditions of the high-pressure reciprocating sealing system and the frequent sealing failures, the performance of large-scale hydraulic equipment is seriously restricted. In this study, the reliability analysis and structural optimization of the reciprocating sealing system were carried out based on CAE analysis and orthogonal test methods. Firstly, a two-dimensional symmetric finite element model of the reciprocating sealing structure was constructed, and the influence of the medium pressure, prepressure and sealing clearance of the sealing system on the performance of the high-pressure reciprocating sealing was simulated and analyzed, and the critical pressure of extrusion at the root of the sealing ring was obtained as 28 MPa. Then, the influence of the key structural parameters of the Y-ring on the sealing reliability was analyzed by the orthogonal test method, and the optimal structural parameters of the Y-ring were determined, and finally the optimized structural parameters were verified by the CAE method. The results show that the optimized structural parameters can effectively control the extrusion of the root of the sealing ring, and can reduce the maximum contact pressure and maximum equivalent stress of the seal, which can effectively improve the reliability of the Y-shaped reciprocating sealing structure under the background of high pressure.

Foil gas dynamic pressure bearing is a kind of adaptive flexible dynamic pressure bearing using ambient gas as the working medium, which has the characteristics of high speed, high efficiency, high temperature resistance and long life. However, under the working condition of high speed, the bearing stability is low, and the structural deformation is easy to occur, which affects the service life. In order to improve the stability of the bearing under high speed conditions, the deformation of wave foil and top foil under high speed conditions is simulated and experimentally studied in this paper. The results show that the bearing of three-lobe foil gas dynamic pressure bearing will shake and deform under high speed conditions. In order to reduce the deformation and optimize its structure, a new structure of three-lobe foil gas dynamic pressure bearing was proposed. The simulation analysis of the optimized structure under high-speed conditions shows that the maximum deformation is reduced from 0.348 mm to 0.344 mm, and the maximum deformation is reduced by 0.989%. It is proved that the new structure of three-lobe foil gas dynamic pressure bearing can effectively control the deformation of wave foil.

The current UAV launch and recovery tasks are often completed using two independent sets of equipment, one for launch and the other for recovery. The operation process is cumbersome and also imposes a significant burden on logistics support. Integrating two devices with different functions into one set of equipment is challenging in engineering. A hydraulic power system with integrated launch and recovery functions is designed to meet the requirement of a new type of UAV support equipment. Compared with a set of original equipment, two functions can be achieved without a significant increase in the number of components. The system can automatically adjust various parameters during launch and recovery. The damping buffer set in the oil cylinder can slow down the high-speed pulley at the launch end. Based on the SimulationX software, the dynamic process of launch and recovery was studied. The launch and recovery function tests are carried out through the manufactured physical prototype. The results show that the system can achieve the launch and recovery functions of UAV, and the simulation and experimental speed error of unmanned aerial vehicles at the launch end does not exceed 3%, which is of great significance for the finalization and mass production of subsequent equipment.

Optimization of the vision recognition algorithm for an apple picking robot is performed, based on the YOLOv8 detection algorithm. To address issues such as missed and false detections and high computational parameters in YOLOv8, a target detection algorithm named YOLOv8-SNC is designed. GSConv is introduced to replace traditional convolution in the Neck part of the algorithm, enhancing its lightweight degree. CBAM attention mechanism is added before each detection head, enhancing the network's feature extraction ability and aligning it with the actual needs of the apple picking robot. Experimental results show a 2.3% increase in precision P and a 1% increase in mean average precisionmAP compared to YOLOv8, with a 9.88% reduction in the number of floating-point operations (FLOPs). YOLOv8-SNC demonstrates better robustness in complex environments such as heavy fruit, leaf occlusion, and multiple targets. It achieves model lightweighting while improving detection accuracy, providing an efficient recognition algorithm for the apple picking robot.

In order to study the influence of design parameters of the oil pump rotor on the performance of the pump, a three-dimensional numerical simulation is conducted on the oil supply stage of an aircraft engine oil pump using the numerical simulation software Pumplinx. The effects of structural design parameters of the internal cycloidal oil pump rotor on its flow rate and flow pulsation rate are specifically studied. When the volume and boundary conditions of the pump are constant, the results indicate that the amplitude and rate of flow pulsation both increase as the speed increases; the flow pulsation rate decreases as the eccentric distance e decreases; the capacity of the pump increases whether the generation coefficient k increases or the arc radius coefficient h decreases; the change of the arc radius coefficient h and generation coefficient k respectively has no direct influence on the flow pulsation rate. The two coefficients need to be combined to determine whether the rotor is too sharp, and sharp rotor will increase the flow pulsation rate.

In the industrial field, the commonly used electro-hydraulic servo valves include direct-drive servo valve, nozzle flapper two-stage servo valve, jet pipe two-stage servo valve and three-stage servo valve. According to the 1176 cases of servo valve failures collected in the service of servo valve, the causes of common servo valve failures are analyzed, classified and statistically studied, which provides a reference for the selection of electro-hydraulic servo valves in the industrial field, and also puts forward suggestions for the use and maintenance of electro-hydraulic servo valves.

In order to meet the demand of high-pressure pneumatic noise processing under some restricted conditions, a small high-pressure muffler suitable for use in narrow enclosed space was designed. The muffler mainly adopts the resistance muffler technology to reduce the pneumatic noise generated by the exhaust of high-pressure gas equipment. The structure adopts the internal and external double support skeleton design to enhance the resistance to high-pressure impact. After testing, the muffler can withstand the impact of 35 MPa high-pressure gas, and the noise reduction can reach more than 45 dB.

Based on the AMESim simulation platform and engineering examples (hose constant tension control system), a mathematical model is established based on the A4VG closed pump and a specially designed valve for proportional and constant voltage control. The variable control mechanism of the pump and the principle of remote constant pressure control regulation are simulated and analyzed. On the basis of simulating the system, the relationship between the set pressure of the remote proportional relief valve and the actual working pressure, as well as the impact of configuring different damping holes on the set pressure of the system, were analyzed. Compared with the scheme of directly adding a relief valve to the pump outlet for pressure regulation, the system has a smaller heat generation and better energy-saving effect, which has played a certain inspiring role in the use of the system under specific working conditions.

The valve controlled motor system plays an significant role in the servo control system of radar turntable, and the electro-hydraulic servo valve is the main control element of high performance valve-controlled motor system. Electro-hydraulic servo valve involves mechanical, electronic, magnetic field, flow field and other multidisciplinary fields, and its mathematical model is more complex. The lack of precise mathematical modeling for electro-hydraulic servo valve in traditional valve-controlled motor system greatly limits the structural design and optimization of electro-hydraulic servo valve. In order to meet the requirements of high precision and high dynamic characteristics of a radar turntable valve-controlled motor system, this paper takes valve-controlled motor system as the research object, and establishes a detailed mathematical model of valve-controlled motor system including key parameters of electro-hydraulic servo valve. Based on MATLAB/Simulink simulation, dynamic characteristic simulation and frequency response analysis of the established system mathematical model are carried out. The research results provide theoretical support and simulation reference for improving the dynamic accuracy of the system and optimizing the structural parameters of the electro-hydraulic servo valve.

Due to the random variation of wind, high complexity of a full-size wind turbine unsteady characteristics, resulting in reproducible experiments results outfield difficult to obtain, and numerical calculation can be effective to provide comparative data. On the basis of ensuring the mesh independence and the accuracy of the calculation process, the numerical calculation of the wind turbine is carried out. Firstly, in a certain experimental condition, the calculation analysis, the pressure distribution and flow field structure of the blade were calculated and analyzed, the results showed that the closer the tip, the higher the degree of fitting of pressure distribution of the calculated value and experimental value, and the closer to the blade root, large-scale three-dimensional separation vortex lead to the greater deviation of the pressure distribution. Secondly, in the whole speed range 4~23 m/s, the flow characteristics and mechanical properties of wind turbine blade were calculated for outfield further experiments, the results show that the three-dimensional rotation effect caused significant delays stall.

The Particle Image Velocimetry (PIV) was used to study the wake flow field characteristics and the vibration characteristics of rectangular blunt body (length-width ratio of 1/2) with Reynolds number Re ranging from 3018 to 10 565 and cantilever spacing s=3D. The experimental results were analyzed by using the Proper Orthogonal Decomposition (POD). The results show that the energy content of the first two POD modes in the blunt body wake is the maximum and the modal frequency is the same, which reflects the large-scale Carmen vortex structure. The modal frequency is vortex shedding frequency. The larger the modal energy content is, the greater the amplitude of the cantilever beam in the wake is; The root-mean-square amplitude y_rms and the dominant vibration frequency f_b of the cantilever beam in the blunt body wake of rectangular cylinder increase linearly with the increase of Re. The first two POD modes are used to reconstruct the wake flow field, and the reaction of the cantilever beam on the flow field structure and the vibration mechanism of the cantilever beam in the rectangular blunt body wake are revealed.