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18 pages, 1709 KiB  
Article
Fluid and Dynamic Analysis of Space–Time Symmetry in the Galloping Phenomenon
by Jéssica Luana da Silva Santos, Andreia Aoyagui Nascimento and Adailton Silva Borges
Symmetry 2025, 17(7), 1142; https://doi.org/10.3390/sym17071142 - 17 Jul 2025
Viewed by 299
Abstract
Energy generation from renewable sources has increased exponentially worldwide, particularly wind energy, which is converted into electricity through wind turbines. The growing demand for renewable energy has driven the development of horizontal-axis wind turbines with larger dimensions, as the energy captured is proportional [...] Read more.
Energy generation from renewable sources has increased exponentially worldwide, particularly wind energy, which is converted into electricity through wind turbines. The growing demand for renewable energy has driven the development of horizontal-axis wind turbines with larger dimensions, as the energy captured is proportional to the area swept by the rotor blades. In this context, the dynamic loads typically observed in wind turbine towers include vibrations caused by rotating blades at the top of the tower, wind pressure, and earthquakes (less common). In offshore wind farms, wind turbine towers are also subjected to dynamic loads from waves and ocean currents. Vortex-induced vibration can be an undesirable phenomenon, as it may lead to significant adverse effects on wind turbine structures. This study presents a two-dimensional transient model for a rigid body anchored by a torsional spring subjected to a constant velocity flow. We applied a coupling of the Fourier pseudospectral method (FPM) and immersed boundary method (IBM), referred to in this study as IMERSPEC, for a two-dimensional, incompressible, and isothermal flow with constant properties—the FPM to solve the Navier–Stokes equations, and IBM to represent the geometries. Computational simulations, solved at an aspect ratio of ϕ=4.0, were analyzed, considering Reynolds numbers ranging from Re=150 to Re = 1000 when the cylinder is stationary, and Re=250 when the cylinder is in motion. In addition to evaluating vortex shedding and Strouhal number, the study focuses on the characterization of space–time symmetry during the galloping response. The results show a spatial symmetry breaking in the flow patterns, while the oscillatory motion of the rigid body preserves temporal symmetry. The numerical accuracy suggested that the IMERSPEC methodology can effectively solve complex problems. Moreover, the proposed IMERSPEC approach demonstrates notable advantages over conventional techniques, particularly in terms of spectral accuracy, low numerical diffusion, and ease of implementation for moving boundaries. These features make the model especially efficient and suitable for capturing intricate fluid–structure interactions, offering a promising tool for analyzing wind turbine dynamics and other similar systems. Full article
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22 pages, 323 KiB  
Article
A System of Parabolic Laplacian Equations That Are Interrelated and Radial Symmetry of Solutions
by Xingyu Liu
Symmetry 2025, 17(7), 1112; https://doi.org/10.3390/sym17071112 - 10 Jul 2025
Viewed by 174
Abstract
We utilize the moving planes technique to prove the radial symmetry along with the monotonic characteristics of solutions for a system of parabolic Laplacian equations. In this system, the solutions of the two equations are interdependent, with the solution of one equation depending [...] Read more.
We utilize the moving planes technique to prove the radial symmetry along with the monotonic characteristics of solutions for a system of parabolic Laplacian equations. In this system, the solutions of the two equations are interdependent, with the solution of one equation depending on the function of the other. By use of the maximal regularity theory that has been established for fractional parabolic equations, we ensure the solvability of these systems. Our initial step is to formulate a narrow region principle within a parabolic cylinder. This principle serves as a theoretical basis for implementing the moving planes method. Following this, we focus our attention on parabolic systems with fractional Laplacian equations and deduce that the solutions are radial symmetric and monotonic when restricted to the unit ball. Full article
(This article belongs to the Special Issue Advance in Functional Equations, Second Edition)
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16 pages, 66642 KiB  
Article
Counterintuitive Particle Confinement in a Helical Force-Free Plasma
by Adam D. Light, Hariharan Srinivasulu, Christopher J. Hansen and Michael R. Brown
Plasma 2025, 8(2), 20; https://doi.org/10.3390/plasma8020020 - 26 May 2025
Cited by 1 | Viewed by 963
Abstract
The force-free magnetic field solution formed in a high-aspect ratio cylinder is a non-axisymmetric (m=1), closed magnetic structure that can be produced in laboratory experiments. Force-free equilibria can have strong field gradients that break the usual adiabatic invariants associated [...] Read more.
The force-free magnetic field solution formed in a high-aspect ratio cylinder is a non-axisymmetric (m=1), closed magnetic structure that can be produced in laboratory experiments. Force-free equilibria can have strong field gradients that break the usual adiabatic invariants associated with particle motion, and gyroradii at measured conditions can be large relative to the gradient scale lengths of the magnetic field. Individual particle motion is largely unexplored in force-free systems without axisymmetry, and it is unclear how the large gradients influence confinement. To understand more about how particles remain confined in these configurations, we simulate a thermal distribution of protons moving in a high-aspect-ratio force-free magnetic field using a Boris stepper. The particle loss is logarithmic in time, which suggests trapping and/or periodic orbits. Many particles do remain confined in particular regions of the field, analogous to trapped particles in other magnetic configurations. Some closed flux surfaces can be identified, but particle orbits are not necessarily described by these surfaces. We show examples of orbits that remain on well-defined surfaces and discuss the statistical properties of confined and escaping particles. Full article
(This article belongs to the Special Issue Feature Papers in Plasma Sciences 2025)
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19 pages, 289 KiB  
Article
The Radial Symmetry and Monotonicity of Solutions of Fractional Parabolic Equations in the Unit Ball
by Xingyu Liu
Symmetry 2025, 17(5), 781; https://doi.org/10.3390/sym17050781 - 19 May 2025
Cited by 2 | Viewed by 347
Abstract
We use the method of moving planes to prove the radial symmetry and monotonicity of solutions of fractional parabolic equations in the unit ball. Since the fractional Laplacian operator is a linear operator, we investigate the maximal regularity of nonlocal parabolic fractional Laplacian [...] Read more.
We use the method of moving planes to prove the radial symmetry and monotonicity of solutions of fractional parabolic equations in the unit ball. Since the fractional Laplacian operator is a linear operator, we investigate the maximal regularity of nonlocal parabolic fractional Laplacian equations in the unit ball. The maximal regularity of nonlocal parabolic fractional Laplacian equations guarantees the existence of solutions in the unit ball. Based on these conditions, we first establish a maximum principle in a parabolic cylinder, and the principles provide a starting position to apply the method of moving planes. Then, we consider the fractional parabolic equations and derive the radial symmetry and monotonicity of solutions in the unit ball. Full article
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21 pages, 22092 KiB  
Article
Analysis of Different Guide Elements’ Designs in Hydraulic Cylinders
by Jan Pustavrh, Ana Trajkovski, Vito Tič, Marko Polajnar, Uroš Bohinc and Franc Majdič
Appl. Sci. 2025, 15(9), 4738; https://doi.org/10.3390/app15094738 - 24 Apr 2025
Viewed by 603
Abstract
In this study, the frictional behaviours of three different guide elements—guide rings, labyrinth seals, and hydrostatic bearings—in hydraulic cylinders is investigated experimentally. A modular, double-acting hydraulic cylinder was designed to compare these three different design elements under different pressures (0 bar, 120 bar, [...] Read more.
In this study, the frictional behaviours of three different guide elements—guide rings, labyrinth seals, and hydrostatic bearings—in hydraulic cylinders is investigated experimentally. A modular, double-acting hydraulic cylinder was designed to compare these three different design elements under different pressures (0 bar, 120 bar, and 240 bar), velocities, and radial loads. The results show that the guide rings exhibit the highest friction, especially at high pressures. Labyrinth seals exhibit significantly lower friction and extend the service life of the components. Hydrostatic bearings allow low friction but require precise control of the fluid, which limits their use. The results provide practical guidelines for selecting guide elements and optimising the friction performance, durability, and efficiency of hydraulic systems. We found that the best solution from the points of view of design, friction, and economics is to use labyrinth seals as guiding elements for the fast reciprocal moving rods of hydraulic cylinders. Full article
(This article belongs to the Section Mechanical Engineering)
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15 pages, 6196 KiB  
Article
Analysis and Control of Abnormal Wear of Reciprocating Compressors in Natural Gas Underground Storage Caverns
by Sijia Zheng, Zhixiang Dai, Fei Wang, Feng Wang, Yongbo Wang, Qin Bie, Wei Jiang, Jingdong Chen, Zicheng Peng and Jie Sun
Processes 2025, 13(4), 996; https://doi.org/10.3390/pr13040996 - 26 Mar 2025
Viewed by 403
Abstract
Throughout China’s 14th five-year plan, the national natural gas pipeline network has been interconnected, and the gas quality became increasingly complex. A certain amount of dust particles widely spread in the natural gas pipeline and lead to abnormal wear of the reciprocating compressor’s [...] Read more.
Throughout China’s 14th five-year plan, the national natural gas pipeline network has been interconnected, and the gas quality became increasingly complex. A certain amount of dust particles widely spread in the natural gas pipeline and lead to abnormal wear of the reciprocating compressor’s compression cylinder within the underground storage cavern. The wear characteristics of the compression cylinder are effectively demonstrated based on the tangential impact energy model, and combined with field measurement and the moving-grid method of computational fluid dynamics. The results reveal that the lubricating oil forms “grinding paste” when mixed with dust particles. With an increase in the dust mass concentration from 0.01% to 3.00%, the viscosity of the “grinding paste” increases from 450,800 mPa·s to 1,274,000 mPa·s, and the density increases from 890 kg/m3 to 980 kg/m3. The abnormal wear frequently occurs at the 12 o’clock and 6 o’clock directions of the compression cylinder. When the piston is in the midpoint of the stroke, the wall shear rate and the wear rate are the highest. When the piston is at both endpoints of the stroke, the wall shear rate and the wear rate are the lowest. For every 1000 h of operation without repairing the cylinder, the dust concentration should be controlled below 0.60%. For every 5000 h and 10,000 h of operation without replacing the cylinder, the dust concentration should be controlled below 1.3% and 0.4%. When the dust mass concentration is 0.01%, the wear rate decreases with decreasing lubricating oil viscosity. When the dust mass concentration is 0.51% and 1.0%, and the lubricating oil viscosities are 259,700 mPa·s, 220,500 mPa·s, and 196,980 mPa·s, the wear rate increases dramatically with decreasing lubricating oil viscosity. Full article
(This article belongs to the Topic Oil and Gas Pipeline Network for Industrial Applications)
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12 pages, 1280 KiB  
Proceeding Paper
Risk Analysis of Musculoskeletal Disorders (MSDs) in Workers Handling LPG Gas Cylinders Manually Using the NIOSH Multi-Task Method
by Etika Muslimah, Nugraeni Dwi Hapsari, Muchlison Anis, Much Djunaidi, Fatiha Widiyanti, Melisa Febriani, Siti Nandhiroh, Munajat Tri Nugroho and Dinda Safitri Ramadhani
Eng. Proc. 2025, 84(1), 85; https://doi.org/10.3390/engproc2025084085 - 18 Mar 2025
Viewed by 399
Abstract
The activity of moving LPG gas cylinders at PT XYZ is carried out manually The unloading of 3 kg LPG gas cylinders from the truck to the floor occurs repeatedly. Workers must bend down when moving the cylinder, and a twisting body, so [...] Read more.
The activity of moving LPG gas cylinders at PT XYZ is carried out manually The unloading of 3 kg LPG gas cylinders from the truck to the floor occurs repeatedly. Workers must bend down when moving the cylinder, and a twisting body, so it can cause injuries such as musculoskeletal disorders (MSDs). This activity involved four workers, but those observed were workers 2 and 4 who were tasked with unloading gas cylinders from the truck. This research aims to analyze the MSDs of worker complaints using the Nordic Body Map (NBM) questionnaire, determine the level of risk using the National Institute for Occupational Safety and Health (NIOSH) Multi-Task Method, and provide suggestions for improvement. The research results show that the NBM values for workers 2 and 4 are 59 and 61, respectively, in the medium category, which means they require immediate corrective action. Meanwhile, in the CLI (Composite Lifting Index) origin for the second worker, all gas cylinder stacks are >3, whereas in the CLI destination, all stacks are >2. During the CLI origin and destination of the fourth worker, all stacks have a value of >3, which means the risk of injury is high..Recommendations for improvement are given by reducing the horizontal lifting distance, reducing asymmetrical angles, and using material handling equipment such as the hand trolley. Full article
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16 pages, 5306 KiB  
Article
On the Identification of Mobile and Stationary Zone Mass Transfer Resistances in Chromatography
by Alessandra Adrover and Gert Desmet
Separations 2025, 12(3), 59; https://doi.org/10.3390/separations12030059 - 28 Feb 2025
Cited by 1 | Viewed by 570
Abstract
A robust and elegant approach, based on the Two-Zone Moment Analysis (TZMA) method, is proposed to assess the contributions of the mobile and stationary zones, HCm and HCs, to the C term HC in the van Deemter [...] Read more.
A robust and elegant approach, based on the Two-Zone Moment Analysis (TZMA) method, is proposed to assess the contributions of the mobile and stationary zones, HCm and HCs, to the C term HC in the van Deemter equation for plate height. The TZMA method yields two formulations for HCm and HCs, both fully equivalent in terms of HC, yet offering different decompositions of the contributions from the mobile and stationary zones. The first formulation proposes an expression for the term HCs that has strong similarities, but also significant differences, from the well-known and widely used one proposed by Giddings. While it addresses the inherent limitation of Giddings’ approach—namely, the complete decoupling of transport phenomena in the moving and stationary zones—it introduces the drawback of a non-unique decomposition of HC. Despite this, it proves highly valuable in highlighting the limitations and flaws of Giddings’ method. In contrast, the second formulation not only properly accounts for the interaction between the moving and stationary zones, but provides a unique and consistent decomposition of HC into its components. Three different geometries are investigated in detail: the 2D triangular array of cylinders (pillar array columns), the 2D array of rectangular pillars (radially elongated pillar array columns) and the 3D face-centered cubic array of spheres. It is shown that Giddings’ approach significantly underestimates the HCs term, especially for porous-shell particles. Its accuracy is limited, being reliable only when intra-particle diffusivity (Ds) and the zone retention factor (k) are very low, or when axially invariant systems are considered. Full article
(This article belongs to the Section Chromatographic Separations)
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19 pages, 5752 KiB  
Article
Numerical Investigation of Flow and Heat Transfer from Twin Circular Cylinders Present in Double Forward-Facing Step
by Parthasarathy Rajesh Kanna, Yaswanth Sivakumar, G. V. Durga Prasad, Dawid Taler, Tomasz Sobota and Jan Taler
Fluids 2025, 10(2), 48; https://doi.org/10.3390/fluids10020048 - 12 Feb 2025
Cited by 1 | Viewed by 750
Abstract
A numerical simulation of the circular cylinder as an obstacle in a double forward-facing (DFFS) step was performed. The size and position of the upstream cylinder (c1) and downstream cylinder (c2) were varied to explore their role [...] Read more.
A numerical simulation of the circular cylinder as an obstacle in a double forward-facing (DFFS) step was performed. The size and position of the upstream cylinder (c1) and downstream cylinder (c2) were varied to explore their role in heat transfer in both laminar and turbulent conditions. Comparative results of the upper and lower half of the downstream cylinder were plotted as results to understand the heat transfer and flow characteristics around the downstream cylinder due to the effect of the upstream cylinder’s dimension and position. For Re = 800, when the c1 is placed near the bottom of the wall, it results in a pair of rear-side symmetrical vortices, and the c2 cylinder vortices become larger when the c1 is shifted towards the top wall. Additional flow separation happens adjacent to the steps when c1 is greater than c2. These vortices strongly influence the convection heat transfer from the step. However, when Reynolds number (Re) is increased from 800 to 80,000, these vortices’ size is decreased. When c1 moves from 0.375H to 0.75H, the average Nusselt number is increased significantly. Moreover, a hike in Re results in a higher average Nusselt number irrespective of the position of obstacles. The upstream cylinder significantly enhances the Nusselt number when it is placed near the top wall rather than the bottom wall. Full article
(This article belongs to the Section Heat and Mass Transfer)
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20 pages, 2322 KiB  
Article
A Study of Forced Convection in Non-Newtonian Hybrid Nanofluids Embedded in a Heated Cylinder Within a Hexagonal Enclosure by Finite Element Method
by Md. Noor-A-Alam Siddiki, Saiful Islam, Mahtab U. Ahmmed, Md Farhad Hasan and Md. Mamun Molla
Mathematics 2025, 13(3), 445; https://doi.org/10.3390/math13030445 - 28 Jan 2025
Viewed by 829
Abstract
Nanofluids have the proven capacity to significantly improve the thermal efficiency of a heat exchanging system due to the presence of conductive nanoparticles. The aim of this study is to simulate the forced convection on a non-Newtonian hybrid with a nanofluid (Al2 [...] Read more.
Nanofluids have the proven capacity to significantly improve the thermal efficiency of a heat exchanging system due to the presence of conductive nanoparticles. The aim of this study is to simulate the forced convection on a non-Newtonian hybrid with a nanofluid (Al2O3-TiO2-H2O) in a hexagonal enclosure by the Galerkin finite element method (GFEM). The physical model is a hexagonal enclosure in two dimensions, containing a heated cylinder embedded at the center. The bottom, middle left, and right walls of the enclosure are all considered cold (Tc), while the top wall is considered to be moving, and the remaining middle, upper left, and right walls have the adiabatic condition. The Prandtl number (Pr = 6.2), Reynolds number (Re = 50, 100, 300 and 500), power law index (n = 0.6, 0.8, 1.0, 1.2 and 1.4), volume fractions of nanoparticles (ϕ = 0.00, 0.01, 0.02, 0.03 and 0.04), and Hartmann numbers (Ha = 0, 10, 20 and 30) are considered in the model. The findings are explained in terms of sensitivity tests and statistical analysis for various Re numbers, n, and Ha numbers employing streamlines, isotherms, velocity profiles, and average Nusselt numbers. It is observed that the inclusion of ϕ improves the convective heat transfer at the surging values of Re. However, if the augmenting heat transfer requires any control mechanism, integrating a non-zero Ha number is found to stabilize the system for the purpose of thermal efficacy. Full article
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27 pages, 12035 KiB  
Article
Numerical Study on Hydrodynamic Performance and Vortex Dynamics of Multiple Cylinders Under Forced Vibration at Low Reynolds Number
by Fulong Shi, Chuanzhong Ou, Jianjian Xin, Wenjie Li, Qiu Jin, Yu Tian and Wen Zhang
J. Mar. Sci. Eng. 2025, 13(2), 214; https://doi.org/10.3390/jmse13020214 - 23 Jan 2025
Cited by 1 | Viewed by 943
Abstract
Flow around clustered cylinders is widely encountered in engineering applications such as wind energy systems, pipeline transport, and marine engineering. To investigate the hydrodynamic performance and vortex dynamics of multiple cylinders under forced vibration at low Reynolds numbers, with a focus on understanding [...] Read more.
Flow around clustered cylinders is widely encountered in engineering applications such as wind energy systems, pipeline transport, and marine engineering. To investigate the hydrodynamic performance and vortex dynamics of multiple cylinders under forced vibration at low Reynolds numbers, with a focus on understanding the interference characteristics in various configurations, this study is based on a self-developed radial basis function iso-surface ghost cell computing platform, which improves the implicit iso-surface interface representation method to track the moving boundaries of multiple cylinders, and employs a self-constructed CPU/GPU heterogeneous parallel acceleration technique for efficient numerical simulations. This study systematically investigates the interference characteristics of multiple cylinder configurations across various parameter domains, including spacing ratios, geometric arrangements, and oscillation modes. A quantitative analysis of key parameters, such as aerodynamic coefficients, dimensionless frequency characteristics, and vorticity field evolution, is performed. This study reveals that, for a dual-cylinder system, there exists a critical gap ratio between X/D = 2.5 and 3, which leads to an increase in the lift and drag coefficients of both cylinders, a reduction in the vortex shedding periodicity, and a disruption of the wake structure. For a three-cylinder system, the lift and drag coefficients of the two upstream cylinders decrease with increasing spacing. On the other hand, this increased spacing results in a rise in the drag of the downstream cylinder. In the case of a four-cylinder system, the drag coefficients of the cylinders located on either side of the flow direction are relatively high. A significant increase in the lift coefficient occurs when the spacing ratio is less than 2.0, while the drag coefficient of the downstream cylinder is minimized. The findings establish a comprehensive theoretical framework for the optimal configuration design and structural optimization of multicylinder systems, while also providing practical guidelines for engineering applications. Full article
(This article belongs to the Section Ocean Engineering)
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15 pages, 2760 KiB  
Article
Thermal Decomposition of Calcium Carbonate at Multiple Heating Rates in Different Atmospheres Using the Techniques of TG, DTG, and DSC
by Dingxiang Zhuang, Zhengzheng Chen and Bin Sun
Crystals 2025, 15(2), 108; https://doi.org/10.3390/cryst15020108 - 22 Jan 2025
Cited by 5 | Viewed by 4861
Abstract
To grasp the decomposition reaction rule of calcium carbonate in cement raw material, the thermogravimetric analyzer (TG), derivative thermogravimetric (DTG), and differential scanning calorimeter (DSC) were used for analysis. Calcium carbonate samples were heated linearly at multiple heating rates of 10, 20, 30, [...] Read more.
To grasp the decomposition reaction rule of calcium carbonate in cement raw material, the thermogravimetric analyzer (TG), derivative thermogravimetric (DTG), and differential scanning calorimeter (DSC) were used for analysis. Calcium carbonate samples were heated linearly at multiple heating rates of 10, 20, 30, and 40 °C/min in the atmospheres of N2 and 70% N2 + 30% O2, respectively. The decomposition kinetics was investigated using a double extrapolation method. Kinetic parameters of the thermal decomposition and the most probable mechanism function were determined in two different atmospheres. The results show that TG, DTG, and DSC curves moved to a higher temperature with the increase in heating rate, and the addition of O2 in the reaction atmosphere had almost no effect on the change in the decomposition curve. Additionally, the activation energy of the initial state in the formation of the new nucleus obtained using the double extrapolation method was 232.13 kJ/mol in the N2 atmosphere, and the most probabilistic mechanistic function was G(α) = 1 − (1 − α)1/2. The chemical reaction process was consistent with the contracted cylinder mechanism model of phase boundary reaction. Moreover, the activation energy of the initial state in the formation of the new nucleus was 233.79 kJ/mol in the 70% N2 + 20% O2 atmosphere, and the chemical reaction process was consistent with that of the N2 atmosphere. Therefore, these results could determine the decomposition temperature and decomposition rate of calcium carbonate. This was important for understanding the thermal stability and processing temperature range of polymer materials, especially the application and potential in production and scientific research. Full article
(This article belongs to the Section Inorganic Crystalline Materials)
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26 pages, 9447 KiB  
Article
Design and Analysis of an Electric Integrated Work Vehicle for Corn Intertillage Fertilization and Pesticide Spraying
by Dongdong Gu, Jiahan Zhang, Yijie Ding, Yongzhen Wang, Jie Yang, Ge Shi, Bin Li and Junqiang Zhao
Appl. Sci. 2024, 14(23), 11356; https://doi.org/10.3390/app142311356 - 5 Dec 2024
Cited by 1 | Viewed by 1244
Abstract
In response to the situation in the Huanghuai region, where corn fertilization and pesticide application primarily rely on manual methods such as hand broadcasting fertilizer and using manual backpack sprayers, resulting in low levels of mechanization, this study designed an electric integrated work [...] Read more.
In response to the situation in the Huanghuai region, where corn fertilization and pesticide application primarily rely on manual methods such as hand broadcasting fertilizer and using manual backpack sprayers, resulting in low levels of mechanization, this study designed an electric integrated work vehicle in line with the trend of developing new energy. The vehicle is powered by six 12 V, 100 Ah lead-acid batteries and integrates the functions of fertilization and pesticide spraying. It can achieve precise hole-fertilization, applying fertilizer to a depth of 100 to 150 mm near the roots of corn, and can also perform multi-row pesticide spraying. The vehicle’s electronic control system is divided into two functional areas: 220 V and 24 V. The walking system uses a 220 V, 2 kW AC servo motor, which is driven by converting the voltage of the 72 V battery group into a 220 V sine wave AC through an inverter, and the motor speed can be adjusted. The working width is adjusted by two fixed electric cylinders at the top of the rear wheel frame. The user can preset the width through the control panel, and during operation, the electric cylinders can be automatically controlled to the optimal working width via a whisker-type limit switch. Analysis using ADAMS software shows that when the vehicle speed is 2, 3, and 5 km per hour, the opening angles of the duckbill controller are 66°, 58°, and 48°, respectively, indicating that the higher the speed, the smaller the opening angle. This shortens the fertilization interval time and makes the fertilization spacing more stable. The maximum opening angle of the adjacent duckbill is 25°, indicating that the fertilization amount remains stable. When the vehicle is moving in reverse, the duckbill always remains closed, and at different speeds, the opening angle change curve of the duckbill controller is smooth and regular. This vehicle significantly improves the efficiency and precision of corn planting. However, improvements are still needed in battery technology, control system optimization, and the high cost of electric agricultural machinery to promote the widespread application of agricultural mechanization. Full article
(This article belongs to the Section Agricultural Science and Technology)
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17 pages, 5911 KiB  
Article
Enhanced Operation Mode Design and Motion Control of a Dual-Redundancy Electro-Hydrostatic Actuator
by Huatao Jin, Shuanglu Li, Yaobao Yin, Rui Guo, Cheng Fang and Jiangkun Zou
Actuators 2024, 13(12), 474; https://doi.org/10.3390/act13120474 - 23 Nov 2024
Viewed by 1073
Abstract
In dual-redundancy electro-hydrostatic actuators (EHAs), the dual pumps are mainly designed for safety, where the cylinder is controlled mainly by one pump while the other one is standby for redundancy. However, such a strategy is basically like a single-pump-controlled system, and the flow [...] Read more.
In dual-redundancy electro-hydrostatic actuators (EHAs), the dual pumps are mainly designed for safety, where the cylinder is controlled mainly by one pump while the other one is standby for redundancy. However, such a strategy is basically like a single-pump-controlled system, and the flow from the pump may be inaccurate when the cylinder moves slowly, which will affect the motion control performance. A new dual-redundancy EHA is designed, and a series of corresponding operation modes are developed, enabling differential operation of the dual pumps. With the proposed operation modes, the inevitable flow inaccuracy problem of the single pump can be addressed through the coordination control of the dual pumps. In order to achieve better motion tracking performance, a model-based backstepping controller is synthesized, where the nonlinearities and uncertainties of the EHA are handled by model compensation and robust feedback design. Comparative simulations with existing control methods for EHAs are conducted and better motion tracking precision is achieved, especially during low-speed motion. Full article
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25 pages, 20472 KiB  
Article
Meshless Error Recovery Parametric Investigation in Incompressible Elastic Finite Element Analysis
by Essam Althaqafi, Devinder Singh and Mohd Ahmed
Math. Comput. Appl. 2024, 29(5), 87; https://doi.org/10.3390/mca29050087 - 30 Sep 2024
Viewed by 937
Abstract
The meshless displacement error-recovery parametric investigation in finite element method-based incompressible elastic analysis is presented in this study. It investigates key parameters such as interpolation schemes, patch configurations, dilation indexes, weight functions, and meshing patterns. The study evaluates error recovery effectiveness (local and [...] Read more.
The meshless displacement error-recovery parametric investigation in finite element method-based incompressible elastic analysis is presented in this study. It investigates key parameters such as interpolation schemes, patch configurations, dilation indexes, weight functions, and meshing patterns. The study evaluates error recovery effectiveness (local and global), convergence rates, and adaptive mesh improvement for triangular/quadrilateral discretization schemes. It uses meshless moving least squares (MLS) interpolation with rectangular and circular support regions and solves benchmark plate and cylinder problems. It is observed that a circular influence region, a cubic spline weight function, and regular mesh patterns yield a better performance of than an MLS-based error recovery method. The study also concludes that lower dilation index values with rectangular influence regions are preferable for regular meshes, while higher dilation index values with radial influence regions are suitable for preferable meshes to enhance MLS error recovery. Full article
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