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This study presents a meticulous investigation facilitated by a bespoke high-pressure test rig. The rig stands as a cornerstone of the research endeavour, providing the capability to simulate diverse leakage scenarios under controlled conditions. With its capacity to replicate conditions akin to real-world hydraulic systems, including various levels of severity such as healthy operation, moderate leakage and severe leakage. The study delves into the intricate analysis of time-series discharge flow rate signals within this experimental framework. The study utilizes sophisticated signal processing techniques, particularly the Continuous Wavelet Transform (CWT), to observe frequency components and temporal occurrences. Despite prevalent challenges distinguishing between leakage severity levels, the CWT-based analysis provides crucial insights into the dominant low frequencies (2.3–3.3 hz) characterising all leakage conditions. An advanced computer vision-based methodology is devised to address the complexities inherent in leakage differentiation, integrating cutting-edge models such as You Only Look Once (YOLO-V7) and You Only Look Once-Neural Architecture Search (YOLO-NAS). These models are meticulously trained using annotated CWT images of flow rates corresponding to different leakage conditions. Notably, the superiority of YOLO-NAS in terms of both speed and accuracy underscores its efficacy in automated leakage detection. In summary, this comprehensive approach, underpinned by the innovative hydraulic test rig and advanced signal processing coupled with state-of-the-art computer vision techniques, presents a significant advancement in the realm of internal leakage detection in hydraulic systems. [ABSTRACT FROM AUTHOR]

To further enhance the intelligent construction of coal mines and improve the control accuracy of hydraulic support displacement straightness, a digital twin control method for hydraulic support displacement has been proposed. First, a dataset related to hydraulic support is established, and a ridge regression prediction model is developed to achieve digital twin-based displacement decision analysis. Next, by analyzing the mechanical structure and displacement principles of the hydraulic supports, a hydraulic cylinder mathematics model is established, leading to the state-space representation of the controlled object. This study focuses on error control during the multi-agent operation of the hydraulic supports, designing a corresponding controller and using discretization methods to verify the consistency of output displacement between followers and leaders. Finally, simulation experiments based on the digital twin model of hydraulic supports are conducted, validating that the hydraulic supports can be controlled in formation according to actual production requirements. The digital twin control method enables the precise adaptive displacement control of hydraulic supports and provides valuable insights for the intelligent construction of mining faces. [ABSTRACT FROM AUTHOR]

Intrinsically safe solenoids drive solenoid valves in coal mining equipment. The low power consumption of these solenoids limits the response time of the solenoid valves. Additionally, the low viscosity and high susceptibility to dust contamination of the emulsion fluid often lead to leakage and sticking of hydraulic valves. This study proposes a low-power-driven, large-flux, fast-response three-stage valve structure with an internal displacement feedback device to address these issues. The critical parameters of the valve were optimized using a novel multi-objective optimization algorithm. A prototype was manufactured based on the obtained parameters and subjected to simulation and experimental verification. The results demonstrate that the valve has an opening time of 21 ms, a closing time of 12 ms, and a maximum flow rate of approximately 225 L/min. The driving power of this structure is less than 1.2 W. By utilizing this valve for hydraulic cylinder control, a positioning accuracy of ± 0.15 mm was achieved. The comparative test results show that the proposed structural control error fluctuation is smaller than that of the 3/4 proportional valve. [ABSTRACT FROM AUTHOR]

Regarding the issue of the first domestic double trunnions cutter suction dredger "TianKun" not being able toindependently complete the entire process of switching the upper and lower trunnions on the construction location, the two keycomponents of the upper and lower suction pipelines and maintenance platform that affect on-site switching have been retrofitdesigned to improve the speed and convenience of the whole process of ladder position switching. Aretrofit design scheme wasproposed based on the original ship structure, which uses the rotation of the ladder to drive specialized diagonal short pipes torealize pipeline connection below the waterline, and uses hydraulic cylinders to drive the overall lifting of the maintenanceplatform to realize the location matching between the maintenance platform and the ladder, and the effectiveness and reliabilityof the redesigned components are analyzed and verified through indoor model tests and finite element simulations. The resultsshow that the redesigned pipeline device can effectively center and seal, the redesigned maintenance platform structure isreasonable, and the strength and stiffness meet the requirements for use, which provides an effective solution for theimprovement of double trunnions cutter suction dredgers such as "TianKun", and can also provide a reference for future newship design. [ABSTRACT FROM AUTHOR]

The synchronization control of its dual hydraulic cylinder moving beam in fatigue testing machine requires robustness and high synchronization accuracy. The synchronization control accuracy is affected by the time-varying nonlinearity of parameters, mutual coupling and load disturbance of the multi-cylinder system affect. A novel control strategy with single-cylinder self-immunity and double-cylinder fuzzy single neuron is proposed to overcome the slow compensation response and poor robustness of dynamic adjustability. First the working principle of the moving beam synchronization system of the fatigue testing machine is described, then the mathematical simulation model of the asymmetric single and double cylinders and their synchronization control system are established to carry out the simulation analysis of the tracking performance and synchronization performance. Finally the experimental is setup to verify the simulation analysis. The results show that the designed synchronization controller can meet the application requirements of the fatigue testing machine moving beam extremely well. [ABSTRACT FROM AUTHOR]

Among various motor-controlled hydraulic cylinder (MCC) topologies, the two-motor-two-pump (2M2P) MCC distinguishes itself through several notable advantages, including precise cylinder pressure control and eliminating mode switch oscillations. Nevertheless, there are challenges remaining in fully realizing its operations across four quadrants and establishing an effective load-holding function within these operations. This study bridges this gap by implementing a 2M2P MCC prototype on a laboratory knuckle boom crane, enabling operation across all four quadrants. Experimental results indicate that position tracking errors remain within ±2.5 mm across three cases, which is well below 1% of the total cylinder travels in the experiments. Furthermore, smooth intersection of cylinder-bore-side and rod-side pressures is observed during transitions between quadrants. In conclusion, the proposed 2M2P MCC demonstrates seamless operation throughout all quadrants, with the load-holding function smoothly activating and deactivating in all four quadrants. [ABSTRACT FROM AUTHOR]

The paper describes design and construction process of the unique reconstruction of the historical stone bridge at the lower head of the listed Hořín lock chamber at the confluence of the Vltava and Elbe rivers near Mělník. The original stone arch bridge from 1905 at the outlet of the lock had to be carefully dismantled and rebuilt into a lifting bridge with a vertical lift of 5 m. The goal was to preserve bridges original listed and preserved appearance and enable larger ships to pass under it. The design of reconstruction consisted of proposal of new substructure, new hidden steel superstructure, new hydraulic and mechanical parts and electronical controling system. The original appearence of the stone cladding had to be preserved, so new hidden truss steel kernel was inserted to form the support for the original stone cladding and concrete coupling shell. The stroke of the bridge is controlled electronically by hydraulic cylinders and a system of guides and restraints. The reconstruction of this unique bridge had been carrefully performed under surveilance of National Heritage Office. The project recieved the Czech Construction of the Year 2022 award. [ABSTRACT FROM AUTHOR]

The recovery of energy in hydraulic systems is becoming increasingly essential not only to reduce energy consumption but also to lower carbon emissions into the atmosphere. A significant portion of the articles and studies published address the recovery of potential energy in hydraulic accumulators and its use to compensate for consumption peaks. This article presents a solution for recovering potential energy in a lifting/lowering device equipped with a digital hydraulic cylinder, converting this energy into electrical energy, which is stored in a battery and can later supply power during the operational cycle. [ABSTRACT FROM AUTHOR]

Copyright of Przegląd Elektrotechniczny is the property of Przeglad Elektrotechniczny and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent times, the point absorber Wave Energy Converter (WEC) has gained popularity due to its practicality. Investigating the parameters of the Hydraulic Power Take-Off (HPTO) in the WEC, including hose diameter and check valve variations, is crucial. This study analyzes optimization using the Sequential Quadratic Programming (SQP) method in MATLAB/SimScape, leading to a more comprehensive understanding of the interactions among HPTO components, such as hydraulic cylinders, check valves, hoses, accumulators, motors, and generators. Key system performance indicators, including pressure drop, flow rate, and power output, were assessed in both single and two-point absorber HPTO configurations. The optimization process yielded a maximum hydraulic power output of 7.33 kW, a mechanical power output of 6.41 kW, and an electrical power output of 5.4 kW using a 2-inch hose diameter. Additionally, utilizing a two-point absorber model enhanced power generation capacity by 47.4%, reaching 9.45 kW. The findings highlight the significant pressure drop at the check valve, with the 2-inch hose model experiencing a drop of 31.874 bar. These results demonstrate that optimizing HPTO parameters can significantly improve the efficiency of converting wave energy into electricity, providing valuable design recommendations for WEC technology. [ABSTRACT FROM AUTHOR]

Ni+W coating gained significant attention for designing metal parts, hydraulic cylinders, agricultural rods, and agricultural pumps because of their excellent resistance to wear and corrosion. In this study, Ni+W combined with SiC nanocoatings are successfully prepared on mild steel by utilizing the pulse electrodeposition strategy. The atomic force microscopy, scanning electron microscopy, x-ray diffractometer, energy dispersive x-Ray spectroscopy (EDX), friction wear test, and hardness tester were utilized to further investigate the surface morphology, phase structure, wear properties and hardness of Ni+W combined with SiC nanocoatings, respectively. The results indicated the ~ 32 nm SiC size in nanocoatings with a 6 g/L concentration of electrolyte. The Ni+W combined with SiC nanocoatings deposited at a SiC concentration of 6 g/L had a dense and smooth surface with a depression depth and a bump height of 76.3 nm and 106.6 nm, respectively. The result demonstrates that an uniform and smooth Ni+W combined with SiC nanocoating can be prefabricated by using appropriate plating parameters. The diffraction angles of 41.1, 51.9, and 71.1° correspond to the three diffraction peaks of the Ni+W combined with SiC nanocoatings fabricated at 3 g/L SiC concentration, which are the sharpest of all nanocoatings, corresponding to the (111), (200) and (220) planes of the Ni-W grains, respectively. Moreover, the minimum values of wear depth and wear width of Ni+W combined with SiC nanocoatings fabricated at a SiC concentration of 3 g/L were separately 33.1 μm and 5.6 mm. There are fine scratches and some shallowness on the surface of the Ni+W combined with SiC nanocoatings deposited at SiC concentration of 6 g/L, which indicates the outstanding tribological properties of the nanocoatings. Furthermore, there are Si, Ni, O and C elements present on the surface of the worn Ni+W combined with SiC nanocoatings observed by EDX results. [ABSTRACT FROM AUTHOR]

The importance of loading and unloading operations in the technological process of wood hauling by timber trucks, as well as the need to improve the design of hydraulic manipulators, are considered. The most rational ways to increase the efficiency of their functioning are given. The disadvantages of traditional designs of hydraulic manipulator rotary mechanisms based on rack-and-pinion gears are presented. An improved design of the crank rotary mechanism of the hydraulic manipulator column from six hydraulic cylinders is proposed. The research methodology is based on the use of mathematical modeling. It has been revealed that the accumulated energy for one braking cycle when moving the load is about 1442 J. Considering that timber loading is carried out at a height of approximately 2 m, the recovery system allows approximately 12 % of the rotation energy to be directed to the load lifting operation. Over the entire range of change in the angle of the end of rotation, the recovered energy varies by only 7.1 % – from 1340 to 1442 J, and the load swing amplitude – by 1.2 % – from 0.336 to 0.340 m. It has been determined that with an increase in the length of the guide, the recovered energy decreases slightly – from 1564 to 1428 J (by 8.7 %) – and the load swing amplitude – from 0.344 to 0.339 (by 1.5 %). It has been found that over the entire angular range, the recovered energy varies from 1399 to 1442 J (by 3 %), and the load swing amplitude – from 0.3380 to 0.3393 m (by 0.4 %). The angular unevenness of the recovery efficiency indicators is no more than 3 %. To study the influence of the parameters of the crank rotary mechanism of the hydraulic manipulator column on the efficiency of energy recovery, a multifactor optimization problem has been solved. It has been established that the optimal value of the distance from the crank axis to the movable axes of the hydraulic cylinders of the rotary mechanism of the hydraulic manipulator column is 0.23–0.25 m, the optimal value of the displacement of the crank axis relative to the axis of the manipulator column is 0.17–0.18 m. At the same time, the recovered energy for 1 cycle of load moving is at least 1500 J, and the amplitude of the load swing is no more than 0.35 m.

Hollow cylindrical components of longer length are a crucial necessity in industries catering to products like gun barrels, cylinder liners of ship and locomotive engines, pneumatic and hydraulic cylinders, etc. A highly finished inner surface improves resistance to corrosion, wear, and friction. Conventional magnetorheological (MR) finishing techniques typically use axis-based CNC setups, which are limited in their ability to finish longer components (>30 cm) due to the Z-axis tool restriction. In this work, a novel MR finishing method has been designed and developed that is based on the pneumatic cylinder and has extremely high reach for the length of the hollow cylindrical workpiece thereby successfully mitigating the limitation of conventional CNC-based MR finishing techniques. Using mild steel as the material, the new technique achieved a significant reduction in surface roughness, with a minimum average roughness of 0.059 µm after 150 minutes of finishing. [ABSTRACT FROM AUTHOR]

Hydraulic cylinders are widely used in rudder surface control, landing gear retraction of aircraft. The aircraft could benefit a lot on weight reduction, by the application of the carbon fiber reinforced polymer (CFPR) on the hydraulic cylinder. The design, optimization, manufacture of the CFRP hydraulic cylinder tube without metal liner is systematically studied in this article. In terms of structure design, inspired by natural thorn plants, a bionic thorn‐tooth connection structure is designed to connect CFRP and the metal end. Then the theoretical design method of thorn‐tooth is proposed. It also provides a new solution for the generic technology of CFRP‐to‐metal connection. In terms of CFRP parameters design method, an accurate mechanical model of CFRP hydraulic tube is established, the influence law of CFRP parameters on mechanical properties is explored, and the optimization method of CFRP parameters adapted to new characteristics is proposed. In terms of the manufacturing process, the split manufacturing‐combined molding process with high precision and low cost is developed to fit the characteristics of CFRP hydraulic tube without metal liner. The prototype manufactured by the proposed method has a weight reduction ratio of 62.37% while maintaining performances compared to the original metal hydraulic cylinder tube. This research will bring significant performance gains and considerable economic and environmental benefits to aircrafts. Highlights: The systematic study of CFRP hydraulic tube without metal liner is presented for weight reduction.The bionic thorn‐tooth connection and its parameter design method are proposed.The CFRP parameters design method of CFRP hydraulic tube is established.A manufacturing process adapted to CFRP hydraulic tube without metal liner is developed. [ABSTRACT FROM AUTHOR]

Fertilizer application has been one of the most important facilities to advance agricultural mechanization. Particularly, manual fertilization cannot fully meet the large-scale production in recent years. In this article, a chain reversal trenching and application device was presented for the organic fertilizer in orchards, in order to enhance the trenching depth and uniform fertilization. A reverse-chain trenching mechanism was employed with a fixed trenching blade that moved in the opposite direction of the chain. The soil cutting and simultaneous backfilling were allowed within the trench, as the device progressed. A trenching depth of up to 600mm was achieved in the chain trenching mechanisms. The separate backfilling was reduced to leave no visible trenches on the surface after completion. This design was also a streamlined operation. The mathematical analysis of the trenching blade was conducted to establish a mathematical model using Cartesian coordinate transformations. The relationship equation was derived for the cutting angle. Optimal angle parameters were also provided. According to the trenching depth analysis, the hydraulic adjustment cylinders were selected for the trenching device. A scrapertype fertilizer application mechanism was adopted to develop the discrete element simulation models for both upright and sideways fertilizer application modes. The fertilizer distribution patterns were analyzed under the two modes. While both modes were similarly distributed fertilizer, and the forward-facing mode was more suitable for the operations with the larger fertilizer widths, while the sideward-facing mode was with the smaller fertilizer widths. In the two fertilizer application modes, the sideways application mode had better uniformity, especially at the lower forward speeds. Therefore, the application mode of sideward-facing fertilizer was selected to ensure that all organic fertilizer accurately fell into the trench. A single-factor experiment was carried out to explore the effects of scraper height, angle, and spacing on the normal contact force and coefficient of variation. All three parameters shared a significant impact on the coefficient of variation. In a coefficient of variation of less than 15%, the optimal height, angle, and spacing of the scraper were selected to minimize the normal contact force, resulting in values of 20 mm, 90°, and 180 mm, respectively. According to these optimal parameters of the scraper, the simulation was conducted to yield a coefficient of variation of 6.02% and a normal contact force of 9.03 N, both of which were lower than those before optimization. Subsequently, a physical prototype was fabricated and field-tested. An average coefficient of variation of 8.34% was obtained for fertilizer distribution, indicating better uniformity. Furthermore, the maximum and minimum fertilizer application tests showed that the quantities ranged from 0.8 to 6 kg/m, thus meeting the fertilization requirements of different plots. The trenching performance tests show that the average trenching depths of two operations were 616.0 and 624.4 mm, respectively, with stability coefficients of 93.57% and 92.58%, respectively, both exceeding 90%. The average trenching widths were 305.4 and 295.4 mm, respectively, with consistency coefficients of 96.16% and 95.04%, respectively, both exceeding 95%. Therefore, the device exhibited excellent performance in the fertilizer distribution and trenching operations, fully meeting the agronomic requirements. The findings can provide a new tool for the deep application of organic fertilizers in orchards, indicating the promising potential prospects. Innovative design and efficiency can also offer valuable insights into the agricultural fields. [ABSTRACT FROM AUTHOR]

Traditional valve-controlled hydraulic cylinders are usually very inefficient due to power loss through the control valve. An efficient alternative architecture is to distribute power electrically rather than hydraulically to a group of cylinders and drive each cylinder via individual servomotor-driven pumps. This arrangement is called electrohydrostatic actuation. Such actuators are currently available for power ratings of several hundred watts or greater, but not in the sub-100 W range. This paper details the design, simulation and testing of a piezopump which is intended to address this gap. The motivation is for aerospace applications, and in particular accessory actuators used in the landing gear system. The 10–100 W range is a high-power output for a piezopump, and to achieve this a novel design using disc-style reed valves was developed to allow pumping frequencies above 1 kHz. These high frequencies necessitated the development of custom power electronics capable of delivering 950 V peak-peak sine wave excitation to a largely capacitive load. Experimental results show that the piezopump is capable of delivering over 30 W of hydraulic power, and at no-load can deliver up to 2 L/min of flow at 1250 Hz. Future development includes a transition to multi-cylinder pumps, and improved reed-valve modelling to improve the accuracy of simulated performance. [ABSTRACT FROM AUTHOR]

As part of the research carried out in the field of processing systems and the production process of oil-hydraulic cylinders of large dimensions and power, the specifics of fluid power transmission, in the functioning of hydropower facilities, were analyzed. The research also includes the optimization of the physical–mathematical model of non-stationary processes, which take place inside the chamber of a large hydrocylinder. In parallel with the definition of the optimization model, the work parameters that affect the process of fluid flow and piston movement were determined. The operating and technological construction parameters of the hydraulic cylinder, which most significantly affect the operation of the hydraulic cylinder, were defined, and the observed parameters were optimized, based on which a prototype with improved characteristics compared to existing solutions was realized. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The combine harvester equipped with attitude-adjustment functionality significantly enhances its adaptability to complex terrain but often struggles to maintain the reliability of its mechanisms. Therefore, investigating the dynamic load characteristics of the attitude-adjustment mechanism becomes imperative. This article employed the DEM–FMBD (Discrete Element Method–Flexible Multibody Dynamics) bidirectional coupling simulation method to establish a multibody dynamic model of a tracked combine harvester. The study delved into the interaction mechanism and dynamic stress response characteristics between the tracked chassis and the complex terrain under various height adjustments, lateral adjustment angles, longitudinal adjustment angles, and different field-ridge crossing methods. Finally, the accuracy of the coupled simulation model was validated through a constructed stress detection system. The research findings revealed that the displacement and tilt angle deviation of the hydraulic cylinders utilized to execute the chassis adjustment actions in the constructed coupled simulation model was less than 5%, and the deviation between the simulation results and the actual maximum dynamic stress under multiple working conditions ranged from 7% to 15%. This verification confirmed the effectiveness of the DEM–FMBD coupled simulation method. Under different adjustment conditions, the maximum stress position was consistently distributed in the same area of the left-front and left-rear rotating arms. The primary and secondary effects of the various parts of the adjustment mechanism on the overall reliability of the chassis were as follows: left front > right front > left rear > right rear. By implementing the middle height with the adjustment strategy, the dynamic stress extreme value of the adjustment mechanism can be effectively reduced by 21.98%, thereby enhancing the structural stability of the chassis. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of China Mechanical Engineering is the property of Editorial Board of China Mechanical Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

With the rapid development of marine engineering in recent years, offshore operations have become increasingly common, making wave compensation platforms crucial for safe operations at sea. This paper presents a pendulum-type wave compensation platform specifically designed for wave compensation applications. The main components of this wave compensation platform include a chassis, support base, hydraulic cylinders, telescopic rods, upper platform, three sets of balancing mechanisms, three sets of tilt angle sensors, and a control system. Firstly, to thoroughly understand the compensatory motion of the pendulum-type three-degree-of-freedom wave compensation platform, kinematic analysis of the entire system was conducted, and the motion inverse solution curves of the mechanism were obtained through simulation using motion simulation software. Secondly, to enhance the compensatory response performance of the platform, a fuzzy PID control algorithm was employed to control the system and achieve attitude control of the platform. Finally, through control system simulation, compared to PID control, fuzzy PID reduces system response delay and successfully meets the expected technical requirements and application needs. [ABSTRACT FROM AUTHOR]

Different agronomic requirements, production conditions, and crop species result in varying row spacings. To address the issue of seedling damage caused by pressure when a fixed track width sprayer operates in different row spacings and enhance the accuracy of track width adjustment, this study designed a track width adjustment system for a sprayer based on the agronomic requirements for field management during the early and mid-stages of corn growth and the entire growth period of wheat in Henan Province, China. The designed track width adjustment system for the sprayer comprised transmission mechanisms, telescopic track width adjustment mechanisms, and an electro-hydraulic control system. The control system achieved a precise track width adjustment by controlling the movement of the hydraulic cylinders through electrical signals, forming a closed-loop adjustment system with the aid of sensors. Four control schemes are proposed: classical PID, integral separated PID, fuzzy adaptive PID, and integral separated fuzzy PID. Simulation experiments were conducted using MATLAB to compare these schemes. The results indicated that the integral separated fuzzy PID exhibited the fastest response and highest steady-state accuracy. The performance of the track width adjustment system was validated through field experiments. The results demonstrate that the stability coefficient of variation for the track width adjustment was 3.04%, which is below the 10% threshold required by agricultural machinery standards. Additionally, the average error of the track width adjustment was 13.42 mm, indicating high precision and effectively reducing seedling compression damage during plant protection operations. [ABSTRACT FROM AUTHOR]

Hydraulic excavators, characterized by their high efficiency and versatility, are crucial equipment in engineering construction. During the automatic excavation process, the excavator may experience resonance phenomena, which can affect the stability of the entire system. In order to study the vibration harmonic response of the excavator arm in the process of reciprocating motion, firstly, the model of the excavator arm is designed in three‐dimensional software, and the finite element meshing software is used to perform hexahedral meshing of the excavator arm model and define the material properties. Secondly, the modal analysis of the excavator arm is carried out by finite element simulation software, and the displacement and acceleration harmonic response analysis is carried out using the modal superposition method. Finally, the vibration experiment of reciprocating motion with different frequencies is carried out on the experimental platform of the excavator arm. The simulation and experimental results show that the maximum value of the displacement and acceleration response of the excavator arm corresponds to the frequency near the second‐order intrinsic frequency, and the excavator arm is greatly affected by the second‐order intrinsic frequency; controlling the frequency of the reciprocating motion of the hydraulic cylinder within 13 Hz can effectively avoid the resonance phenomenon of the excavator arm device. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Due to the influence of coal rock shape, hardness, working environment and other factors in the cutting process of cantilever roadheader, the cutting head will produce irregular and violent vibration. As the rotary table of key stress components, its operation process stability, dynamic reliability and life affect the cutting efficiency and cutting stability of cantilever roadheader. In order to study the vibration characteristics of the rotary table in the cutting process, firstly, based on the theory of spatial force analysis and calculation, the spatial mechanical model of the rotary table of the cantilever roadheader is established. By solving the balance equation of the rotary table force system, the variation law of the load at the hinge ear of the rotary table with the cutting pitch angle and the horizontal angle is obtained. Secondly, based on the path transfer analysis method of working condition, the vibration data of cutting head, cutting cantilever, cutting lifting and rotary hydraulic cylinder under stable cutting condition are taken as input signals. By constructing the transfer path analysis model of rotary table working condition, the synthetic vibration of rotary table in cutting process is simulated, and the main vibration source of rotary table is determined. Then, the vibration contribution and contribution degree of each vibration excitation point to the hinge ear of rotary table are studied. By building a cutting test bench, the vibration response of rotary table in cutting process is tested to verify the correctness of the theoretical model.Thirdly, based on the frequency domain analysis method of random vibration fatigue life, combined with the S-N curve of the rotary table, the PSD curve at the maximum stress of the rotary table is obtained by modal excitation method, and the load data is imported into ANSYS nCode software to obtain the life cloud diagram and damage cloud diagram of the rotary table, and then the fatigue life of the rotary table under symmetrical cyclic load is solved. Finally, based on the response surface optimization analysis method, the maximum stress and maximum deformation of the rotary table are taken as the optimization objectives, and the aperture of each hinge ear of the rotary table is taken as the optimization variable. Based on Design Expert, a second-order regression model is established to realize the multi-objective optimization design of the key stress parts of the rotary table in the cutting process. The simulation results show that under the same cutting conditions, the maximum stress of the optimized rotary table is reduced by 15.82% year-on-year, and the maximum deformation is reduced by 24.70% year-on-year. The optimized rotary table structure can better adapt to the cutting process, which is beneficial to improve the service life of the rotary table and enhance its operation stability. The research results are beneficial to enrich the relevant research theory in the field of rotary table vibration of cantilever roadheader, and are beneficial to improve the service life of the rotary table and the efficiency of tunneling and mining. [ABSTRACT FROM AUTHOR]

The model presented in this paper was prepared to determine the pile toe resistance mobilization mechanism. Due to the fact, that skin resistance of piles was widely analyzed by the Authors in previous papers [1,2] which were based on both field and laboratory test results, currently the main focus is to describe the mobilization of pile toe resistance. The physical experimental model consists of a chamber measuring 2.2 m, 2.4 m and 6.0 m in width, length, and height, respectively, filled with cohesionless soil. The model has a hydraulic cylinder to apply force at the pile head and equipment to measure pile settlement with force mobilized at the pile base. The purpose of this research was to verify previously formulated methods referring to the M–K curves. Furthermore, the research allowed us to examine if the relationship between pile toe resistance and force applied at the pile head is linear. As a result of the tests, it was confirmed that for purposes of practical engineering calculations, the resistance of the pile toe can be described regarding the load, which is applied at the pile head. The description of this relationship is presented with M–K curve parameters. [ABSTRACT FROM AUTHOR]

Summary: Rock drilling jumbo is an important large construction machine used for tunneling construction, and its automation has an urgent demand in engineering. However, the electro‐hydraulic system of the rock drilling jumbo has strong parameters uncertainties and some dynamics that are hard to model accurately, which causes certain challenges for designing model‐based high‐performance control algorithms. To solve these challenges, a parameter adaptive based neural network sliding mode control algorithm is proposed to enhance control performance of the electro‐hydraulic system. The parameter adaptive law is developed to estimate unknown parameters of the system, the neural network is applied for compensating unmodeled dynamics, and then the final control law is designed by sliding mode control method, and the stability demonstration of the closed‐loop system is given. In the simulations, the effectiveness of the designed parameter adaptive law is verified. Extensive comparison experiments are performed on a real rock drilling jumbo driven by proportional valves, the experimental results demonstrate that the developed control algorithm obviously improves the control precision of hydraulic cylinder of the rock drilling jumbo compared with the traditional sliding mode and PID control algorithm, thus the designed control algorithm can be expanded and applied for general hydraulic servo control mechanism. [ABSTRACT FROM AUTHOR]

A coupled Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) approach is used to calculate the interaction of a flexible rag transported by a fluid current with a fixed solid cylinder. More specifically a hybrid Eulerian-Lagrangian approach is used with the rag being modeled as a set of interconnected particles. The influence of various parameters is considered, namely the inlet velocity (1.5, 2.0, and 2.5 m/s, respectively), the angle formed by the initially straight rag with the flow direction (45°, 60° and 90°, respectively), and the inlet position (90, 100, and 110 mm, respectively). The results show that the flow rate has a significant impact on the permeability of the rag. The higher the flow rate, the higher the permeability and the rag speed difference. The angle has a minor effect on rag permeability, with 45° being the most favorable angle for permeability. The inlet position has a small impact on rag permeability, while reducing the initial distance between the rag an the cylinder makes it easier for rags to pass through. [ABSTRACT FROM AUTHOR]

Hydraulic power take-off (PTO) is increasingly favored as energy regulation and transmission system in wave energy converters (WEC), significantly smoothing the inherent randomness and fluctuation of wave energy. This paper designed a novel hydraulic PTO system composition of a double-acting hydraulic cylinder pump and accumulators. The dynamic process sub-division principle in an operating period of the hydraulic cylinder pump and accumulator and the mathematical model for explaining the fluctuations of pressure and flow rate in the hydraulic pump and accumulator circuit by means of the sub-division principle are put forward. The MATLAB/Simulink simulation model used to analyze pressure fluctuation in the hydraulic PTO system is established based on the mathematical model. The numerical results and MATLAB simulation results are mutually verified about the fine analysis of the accumulator smoothing fluctuation in the hydraulic PTO system. The results show that the pressure fluctuation amplitude of a hydraulic circuit is negatively correlated with the accumulator pre-charge pressure and the accumulator volume, and is positively correlated with the operating period of a hydraulic pump. The energy transfer efficiency of the hydraulic PTO system with accumulator fine compensation can be above 90%. The theory and model in this paper will serve as a valuable reference for designing fluctuation compensation parameters in hydraulic systems. [ABSTRACT FROM AUTHOR]

The paper presents the results of determining the amplitude-frequency characteristic of the Z14XEP engine vibration of the Opel Astra G (F69) at idle speed depending on the steering wheel position. The opposite of changes in the values of the amplitude and frequency of mechanical vibrations of the engine on its supports was determined: an increase in amplitude and a decrease in frequency under the condition of the beginning of the movement of the hydraulic fluid through the power cylinder of the hydraulic booster. The actuation of the hydraulic boost system with an electric pump drive generally causes an increase in the amplitude of engine oscillations by 24.2% in the longitudinal and vertical planes, which occurred before the fluid was replaced, and by 14.4% after its replacement. It was determined that, regardless of the state of the hydraulic fluid at the beginning of its circulation through the cavities of the amplifier's power cylinder, the frequency of mechanical vibrations of the engine decreases in the longitudinal and vertical planes by 25%. In the transverse plane, the oscillation frequency is reduced by 35%, except when the hydraulic fluid is changed, when the oscillation frequency remains unchanged. It has been established that the quality of the hydraulic fluid of the power steering system significantly affects the change in mechanical vibrations of the engine only when the steering wheel is deviated from the neutral position. It was determined that a decrease in the viscosity of the new hydraulic fluid by 8.3% compared to the fluid that was replaced causes changes only in the amplitude of engine oscillations. In the longitudinal plane, the oscillation amplitude decreases by 13.3%, in the vertical plane - by 15.1%, and in the transverse plane, the oscillation increases by 25.4%. Reducing the viscosity of the hydraulic fluid used reduced the resistance to its movement through the holes, channels and pipelines of the power steering system and reduced the power take-off to drive the power steering pump. [ABSTRACT FROM AUTHOR]

Adaptive active suspension systems, integral to specialized vehicles, hold significance for their stability and safety. This study introduces a novel adaptive active suspension system featuring four independently controlled wheels employing wheel-hub motors, hydraulic cylinders, pump motor power, controllers, and sensors. A rapid and, within a certain range, leveling and height adjustment control strategy is proposed for this system, utilizing the Kalman filter algorithm. Additionally, the paper examines the front-wheel Ackermann steering model and four-wheel reverse Ackermann transition model to enhance the suspension's stability. Subsequently, experiments on leveling and height adjustment are conducted, demonstrating the system's capability to swiftly and accurately rectify the vehicle's deviation angle within the specified threshold. Following adjustments made by the leveling and height control algorithm, the vehicle body promptly returns to the preset level state and designated height. The leveling control system holds broad applicability in intelligent agriculture, logistics handling, off-road equipment, and other domains, presenting significant practical utility. [ABSTRACT FROM AUTHOR]

In Russia, a significant number of power facilities built in the 1960s and 1970s are located in regions where seismic effects were revised upward. This has led to an increase in the seismicity of the sites of facilities' locations by magnitude 1–2 (MSK-64) in comparison with the data of design documentation. During the long-term operating period of power facilities, the load-bearing capacity of building structures, as a rule, decreases. This article presents the results of computational and experimental studies of reinforced concrete structures of thermal power plants and hydroelectric power plants for seismic effects in the range of magnitude 4–10 (MSK-64). The computational studies were carried out using ANSYS 16.0 software, and experimental studies were carried out on stands modeling seismic impacts with the help of hydraulic cylinders. The results of the studies showed that cracking of reinforced concrete structures without strengthening occurs at magnitude 6.0 (MSK-64) of seismic impact, and destruction occurs at magnitude 7.5. Thus, the seismic resistance of structures without reinforcement does not meet the requirements for seismic resistance, and strengthening is required. This study considers a variant of strengthening based on external composite reinforcement with CFRP. It is shown that the strengthening of structures with composite material increases their earthquake resistance up to magnitude 9–10 (MSK-64). This article presents recommendations on the CFRP strengthening of building structures of power facilities, both after receiving damage under seismic impact and in a planned manner to increase seismic resistance. The novelty of this work lies in the fact that quantitative results of increasing the seismic resistance of structures depending on the placement and number of layers of composite material are given. [ABSTRACT FROM AUTHOR]

In order to obtain the optimal cladding process parameters for repairing the inner wall of the cylinder, 316L stainless steel powder was laser clad onto 27SiMn steel, which is the base material of the inner wall of the cylinder. The CCD (Central Combination Design) experiment scheme was designed by the response surface method. A surrogate model between input variables (laser power, scanning speed, and powder-feeding speed) and response values (intactness, dilution rate, and the micro-hardness of the cladding layer) was established. The adaptive chaotic differential evolution algorithm (ACDE) was used to optimize the process parameters and the optimization results were verified by experiments. The results show that the optimum parameters are a laser power of 1350 w, a scanning speed of 11.7 mm/s, and a powder-feeding rate of 2.5 g/min. After cladding, the macroscopic quality of the cladding layer was increased by 11.1%, the micro-hardness was increased by 7.1%, and the dilution rate was reduced by 24.7%. During the friction wear experiments, it was found that the maximum wear depth of the optimal specimen was 149.72 μm, which was smaller and more wear-resistant than the specimen in the control group. The results provide theoretical data for the repair and strengthening of the inner wall of the hydraulic support cylinder. [ABSTRACT FROM AUTHOR]

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Machine Tool & Hydraulics is the property of Guangzhou Mechanical Engineering Research Institute (GMERI) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper presents the design of an intra-row obstacle avoidance shovel-type weeding machine. Theoretical analysis of intra-row weeding components guided the determination of the structures and parameters for key parts, including the signal acquisition mechanism, automatic obstacle avoidance mechanism, and weeding shovel. Furthermore, a hydraulic system was designed to support these functions. The design aims to optimize intra-row weeding operations, reduce labor costs, enhance weed control effectiveness, and prevent collisions between weeding equipment and grapevines. Through the construction of a mathematical model, the analysis determined the necessary minimum return speed of the hydraulic cylinder for the intra-row weeding shovel to avoid grapevines. We also established a reasonable range for the extension speed of the hydraulic cylinder to minimize areas missed during weeding. Further analysis showed that using the minimum return speed of the hydraulic cylinder effectively reduced missed weeding areas. A virtual prototype model of the weeding machine was created in ADAMS. Using the coverage rate of weeding operation as the evaluation index, single-factor simulation tests determined that the extension speed of the piston rod in the obstacle avoidance hydraulic cylinder and the forward speed of the weeding machine are the main influencing factors. The preset threshold of the control system, which triggered the automatic obstacle avoidance mechanism when the obstacle avoidance rod reached a specific angle (the "Angle Threshold"), was identified as a secondary influencing factor. Other factors were considered irrelevant. Hydraulic cylinder extension speed, weeding machine forward speed, and angle threshold were chosen as the influencing factors. Following the principles of a Box–Behnken experimental design, a quadratic regression combination experiment was designed using a three-factor, three-level response surface analysis method. The evaluation criterion focused on the coverage rate of weeding operation. A regression model was developed to determine the coverage rate of the weeding operation, identifying the optimal parameters as follows: obstacle avoidance hydraulic cylinder extension speed of 120 mm/s, forward speed of the weeding machine at 0.6 m/s, and an angle threshold of 18°. The optimized coverage rate of the weeding operation achieved 86.1%. This study serves as a reference for further optimization of intra-row weeding machines in vineyards and for other crops. [ABSTRACT FROM AUTHOR]

The three-point hitch, found on agricultural tractors, facilitates the raising and lowering of an attached implement. Some tractors include a rock shaft that comprises a physical shaft that interconnects and facilitates the raising and lowering of the lower arms of the three-point hitch in a synchronized manner. In this study, we deal with a hitch system with the lower arms actuated by two independent hydraulic cylinders. This innovative tractor hitch system design allows the implement to follow the terrain, instead of the tractor, about the fore–aft (roll) axis of the tractor. However, since the two lower arms are independent, a specialized controller is needed to move these arms in unison. First, we present a position controller for individual arms and a roll controller to move these arms together. Second, we present a unique algorithm to emulate a physical rock shaft while the implement is operating in float mode. The algorithm ensures that the implement does not roll around the fore–aft axis while making sure it moves up and down vertically to follow the terrain. We present experimental results from the step response of the hitch system's height while tracking a velocity reference. With the roll of the implement defined as the difference between the left arm's position in percentage and that of the right arm in percentage, we observe that the largest mean roll was 0.23% with a flail mower attached and 0.26% without any implement. We then present results from the implement's position in the float mode when the software rock shaft was activated and compare them with the case without the software rock shaft. The experiments showed that, when the software rock shaft was turned on, the mean roll reduced from 4.64% to 0.58% with a seed drill implement and from −3.99% to −0.59% with a flail mower implement. The standard deviations in these two implement cases improved from 16.77% to 2.79% and 6.45% to 3.53%, respectively, proving the effectiveness of the software rock shaft and its potential to replace the physical rock shaft found on the traditional tractors. [ABSTRACT FROM AUTHOR]

This paper is concerned with a hydraulic cylinder directly controlled by a variable speed motor-driven fixed-displacement pump. The considered configuration is referred to as a one-motor-one-pump (1M1P) motor-controlled hydraulic cylinder (MCC). A 1M1P MCC with a hydraulically driven passive load-holding function enabled by controlled system pressures is proposed. The proposed load-holding functionality works if there is a standstill command, a loss of power supply, or a hose rupture. Additionally, this paper conducts a comprehensive analysis of the proposed system's operation and load-holding function across four quadrants. The simulation results demonstrate four-quadrant operation and good load-holding performance under the aforementioned scenarios. In conclusion, the proposed 1M1P MCC can be successfully used on practical applications characterized by overrunning loads and four quadrant operation. [ABSTRACT FROM AUTHOR]

Fluidic actuation systems are optimizable as to energy consumption by reducing the friction in the hydraulic cylinders. Polymeric materials with special antifriction properties and good resistance to hydraulic fluids can be deployed to enhance the performance of hydraulic cylinders. Small friction forces can also be ensured by facilitating the hydrodynamic separation of the elements of the friction tribosystem, namely the seal and sealed-off surface, respectively. The study presented in this paper analyzed the hydrodynamic separation phenomenon in hydraulic cylinders with coaxial sealing systems of the pistons. The process underlying the forming of the fluid film between the seal and its contact surface was considered and the formula for calculating film thickness was deduced. This paper presents graphs that describe the variation of the fluid film thickness versus the dimensional and material characteristics of the sealing systems. The study yielded recommendations as to the most adequate polymeric material to be used and the optimum dimensional characteristics of the seal. [ABSTRACT FROM AUTHOR]