Search Results (2,444)

This study addresses the problems of poor dynamic stability, high vibration coupling, and inefficient energy use in large-farm manure handling machines. A profiling wheel-based multi-disciplinary approach is proposed in the study. With the rocker arm prototype, double-ball heads, and a hydraulic damping system, a parametric design is built that includes vibration and energy consumption. The simulation results in EDEM2022 and ANSYS2022 prove the structure viability and motion compensation capability, while NSGA-II optimizes the damping parameters (k₁ = 380 kN/m, C = 1200 Ns/m). The results show a 14.7% σ_Fc reduction, 14.3% α_RMS decrease, resonance avoidance (14–18 Hz), Δx (horizontal offset of the frame) < 5 mm, 18% power loss to 12.5%, and 62% stability improvement. The new research includes constructing a dynamic model by combining the Hertz contact theory with the modal decoupling method, while interacting with an automatic algorithm of adaptive damping and a mechanical-hydraulic-control-oriented optimization platform. Future work could integrate lightweight materials and multi-machine collaboration for smarter, greener manure cleaning. Full article

Polar environmental research requires advanced detection methods to understand rapid changes in these regions. Unmanned aerial vehicles (UAVs) bridge the gap between satellite remote sensing and in situ ice-based buoy measurements, offering improved spatiotemporal resolution and operational efficiency. However, their widespread use in polar regions remains limited due to insufficient endurance capabilities. To address this problem, this paper presents a new monitoring system, the so-called UAV and Ice-based buoy cross-domain observation system (UBCOS). Particularly, the ice-based buoy integrates a Real-Time Kinematic (RTK) base station, a contact-based charging system, and an Iridium communication system, providing UAVs with centimeter-level positioning correction, low-temperature charging support, and remote data transmission capabilities. UAVs equipped with pod-mounted cameras capture imagery of sea ice surface characteristics within a 4 km radius of the buoy. Field tests conducted in the Arctic in 2024 demonstrate that the system achieved expected performance in both monitoring task execution and data collection, validating its practicality and reliability for polar sea ice monitoring. Full article

The dynamic contact problem describing collision of an elastic bar with a rigid obstacle, prescribed by an initial velocity, is considered in a variational formulation. The non-smooth, piecewise-linear solution is constructed analytically using partition of a 2D rectangular domain along characteristics. Challenged by the discontinuous velocity after collision, full discretization of the problem is applied that is based on a space-time finite element method. For an iterative solution of the discrete variational inequality, a primal–dual active set algorithm is used. Computer simulation of the collision problem is presented on uniform triangle grids. The active sets defined in the 2D space-time domain converge in a few iterations after re-initialization. The benchmark solution at grid points is indistinguishable from the analytical solution. The discrete energy has no dissipation, it is free of spurious oscillations, and it converges super-linearly under mesh refinement. Full article

The sealing performance of ultra-high-pressure solenoid valves faces significant challenges, particularly under low-temperature conditions. Due to the difference in thermal expansion coefficients between the valve seat and the sealing tube, combined with material contraction at low temperatures, the bolt preload decreases, and consequently the contact force on the sealing surface and the average sealing specific pressure are reduced. This may result in an average sealing specific pressure falling below the required sealing specific pressure, causing leakage and failure of the ultra-high-pressure solenoid valve. To address this problem, this study utilizes theoretical and simulation analysis to examine the preload status in low-temperature environments and the causes of sealing failure in ultra-high-pressure solenoid valves. A corresponding optimization scheme is proposed, which involves increasing the torque from 120 N·m to 130 N·m and applying sealant to the threaded connection to enhance the sealing performance of the ultra-high-pressure solenoid valve. Following the increase in tightening torque and the application of thread sealant, the helium leakage rate at −40 °C is significantly reduced. Specifically, at a test pressure of 87.5 MPa, the helium leakage rate decreases from $1.6\times {10}^{-5}$ mbar·L/s to approximately $1.4\times {10}^{-6}$ mbar·L/s. At test pressures of 1.4 MPa and 10 MPa, the leakage rate is approximately $3.0\times {10}^{-7}$ mbar·L/s. Experimental verification shows that the proposed solution can significantly enhance the sealing reliability of ultra-high-pressure solenoid valves under extreme operating conditions. Full article

In order to solve the problem that it is difficult to take into account the performance constraints between the core functions of insulation, current flow and arc extinguishing of high-voltage vacuum circuit breakers at the same time, this paper proposes a flexible control strategy for the motor operating mechanism of high-voltage vacuum circuit breakers. The relationship between the rotation angle of the motor and the linear displacement of the moving contact of the circuit breaker is analyzed, and the ideal dynamic curve is planned. The motor drive control device is designed, and the phase-shifted full-bridge circuit is used as the boost converter. The voltage and current double closed-loop sliding mode control strategy is used to simulate and verify the realization of multi-stage and stable boost. The experimental platform is built and the experiment is carried out. The results show that under the voltage conditions of 180 V and 150 V, the control range of closing speed and opening speed is increased by 31.7% and 25.9% respectively, and the speed tracking error is reduced by 51.2%. It is verified that the flexible control strategy can meet the ideal action curve of the operating mechanism, realize the precise control of the opening and closing process and expand the control range. The research provides a theoretical basis for the flexible control strategy of the high-voltage vacuum circuit breaker operating mechanism, and provides new ideas for the intelligent operation technology of power transmission and transformation projects. Full article

The design of the buckling configuration for a rolling soft robot has a significant effect on its rolling performance, but a thorough analysis remains lacking for many soft robot buckling configurations because of the difficulty of analyzing the buckling problem. This work comprehensively analyzes the static buckling morphology of two nested elastic rings under gravity based on a theoretical model using the minimum potential energy principle. Two nested rings present a tank-track-like buckling morphology under gravity, which depends on the length ratio, the bending stiffness ratio, and the gravity ratio of the inner ring to the outer ring. Increases in these three ratios lead to a lower tank-track-like buckling structure with an increased ground contact length and a reduced gravity moment on the slope. The tank-track-like buckling structures predicted using the theory agree well with Finite Element Method (FEM) simulations and experimental results. This work provides design guidance on achieving the maximum slope stability and the required robot configuration by tuning the geometrical and material parameters of rolling soft robots. Full article

Aiming at the problem of lacking accurate and reliable contact and bonding parameters in the discrete element simulation of whole cotton stalk harvesting equipment, this study proposed a reverse modeling method for cotton roots combining the Discrete Element Method (DEM) with 3D laser scanning. This method systematically constructed a general discrete element model and completed its parameter calibration. Firstly, cotton root samples were collected and measured to obtain key morphological parameters, providing a basis for selecting representative roots and performing 3D reverse reconstruction. Subsequently, mechanical parameters and contact parameters of the cotton roots were measured and calibrated through mechanical tests and stacking angle tests. Furthermore, based on the Hertz–Mindlin with Bonding contact model, a structured root sample model was established using a layered particle combination strategy. The bonding parameters were then optimized and calibrated through shear and tensile mechanical simulation experiments. Finally, a discrete element model of the root–soil complex was established based on the optimal parameter set. The reliability of the model was validated by comparing the simulation results with physical field tests of root extraction force. The results indicated that in the contact parameter validation test, the relative error between the simulated stacking angle and the measured value was only 0.43%, demonstrating the high accuracy of the model in simulating contact characteristics. In the bonding parameter calibration validation tests, the relative errors between the simulation results and measured values for shear and tensile mechanics were 1.22% and 1.40%, respectively, indicating that the model parameters could accurately simulate shear strength and tensile strength. Finally, in the root extraction force validation test, the relative error between the simulated extraction force and the field-measured value was 3.76%, further confirming the model’s applicability for analyzing the complex interaction mechanisms between roots and soil. The findings of this study can provide key models and parameter support for the digital design, operation process simulation, and performance optimization of whole cotton stalk harvesting equipment. Full article

The large amounts of chrome-tanned leather waste (CLTW) produced annually can be valorized by applying circular economy principles in various fields due to the valuable substances contained (mainly collagen). The main problem for the direct valorization of these wastes is the presence in their composition of dangerous substances, such as chromium. Thus, before being used as raw material in new processes, chrome-tanned leather waste must be subjected to a preliminary stage of chromium removal. In this article, we propose to identify the optimal working conditions for the extraction of chromium ions from chrome-tanned hides in the presence of oxalic acid with various concentrations, at various temperatures and contact times, so that the degree of collagen hydrolysis is minimal. In this sense, the response surface methodology (RSM) method was used to optimize the working conditions, to maximize the efficiency of chrome extraction from the leather, and to minimize the efficiency of collagen hydrolysis: An undesirable process. To optimize both the extraction yield (%) and the degree of hydrolysis (%), the key operational variables, namely oxalic acid concentration (%), contact time (%), and temperature (°C), were systematically adjusted using the Box–Behnken design within the response surface methodology (RSM). The most favorable extraction conditions were identified at an oxalic acid concentration of approximately 7%, a contact time close to 120 min, and a temperature near 49 °C. Under these optimized parameters, the hydrolysis degree remained very low, around 0.38%, indicating minimal degradation during the process. Full article

Light attenuation and excess handling of light-cured luting agents create problems in bonding veneer restorations. The aim of the present study was to assess the curing capacity of light-cured veneer luting agents (VLA) [Choice 2 (CH2), G-Cem Veneer (GCV), Panavia LC Veneer (PNV), PermaCem LC Veneer (PMS), and Variolink Esthetic LC (VEV)] under lithium disilicate veneers, in the presence or absence of touch-cure primers (Adhese Universal Bond DC for VEV, G Premio Bond + DCA Activator for GCV, and V5 Tooth Primer V5 for PNV) and to evaluate material setting under two tack-curing irradiation modes (contact, distant). The methods used were ATR–FTIR spectroscopy and Vickers hardness (VHN) tests (n = 5/product and test). According to the results, all materials cured under the ceramic demonstrated significantly lower DC% from the controls, with a ranking of VEV, CH2 > GCV, PMS, PNV. The primers improved DC% by 4–13% only in the veneer groups. Tack-curing in contact mode demonstrated conversion and hardness values ranging from 37% to 78% and 31% to 57% of the controls respectively, corresponding to a vitreous state. For the distant mode, very low conversion values were found (0–7% of the controls), with untraceable indentations. It can be concluded that low translucency veneers reduce conversion of VLAs, which can be improved by using touch-cure activators. Tack-curing, as instructed, creates vitrified materials, resulting in difficult removal of set excess, which implies the need for better standardization of the procedure. Full article

A miniaturised bionic electronic nose system was developed to solve the problems of expensive equipment and long response time for soil pesticide residue detection. The structure of the bionic electronic nasal cavity is designed based on the spatial structure and olfactory principle of the sturgeon nasal cavity. Through experimental study, the structure of the nasal cavity of the sturgeon was extracted and analyzed. The 3D model of the bionic electronic nasal cavity was constructed and verified by Computational Fluid Dynamics (CFD) simulation. The results show that the gas flow distribution in the bionic chamber is more uniform than that in the ordinary chamber. The airflow velocity near the sensor in the bionic chamber is lower than in the ordinary chamber. The eddy current intensity near the bionic chamber sensor is 2.29 times that of the ordinary chamber, further increasing the contact intensity between odor molecules and the sensor surface and shortening the response time. The 10-fold cross-validation method of K-Nearest Neighbor (K-NN), Random Forest (RF) and Support Vector Machine (SVM) was used to compare the recognition performance of the bionic electronic nasal cavity with that of the ordinary electronic nasal cavity. The results showed that, when the bionic electronic nose detection system identified the concentration of pesticide residues in soil, the recognition rate of the above three recognition algorithms reached 97.3%, significantly higher than that of the comparison chamber. The bionic chamber electronic nose system can improve the detection performance of electronic noses and has a good application prospect in soil pesticide residue detection. Full article

The improvement of comfort in the human–robot interaction for care recipients is a significant challenge in the development of nursing robots. The existing methods for enhancing comfort largely depend on subjective comfort questionnaires, which are prone to unavoidable errors. Additionally, traditional passive movement control approaches lack the ability to adapt and effectively improve care recipient comfort. To address these problems, this paper proposes an active, personalized intelligent control method based on neural networks. A muscle activation prediction model is established for the piggyback transfer robot, enabling dynamic adjustments during the care process to improve human comfort. Initially, a kinematic analysis of the piggyback transfer robot is conducted to determine the optimal back-carrying trajectory. Experiments were carried out to measure human–robot contact forces, chest holder rotation angles, and muscle activation levels. Subsequently, an Online Sequential Extreme Learning Machine (OS-ELM) algorithm is used to train a predictive model. The model takes the contact forces and chest holder rotation angle as inputs, while outputting the latissimus dorsi muscle activation levels. The Genetic Algorithm (GA) is then employed to dynamically adjust the chest holder’s rotation angle to minimize the difference between actual muscle activation and the comfort threshold. Comparative experiments demonstrate that the proposed ELM-GA-based active control method effectively enhances comfort during the piggyback transfer process, as evidenced by both subjective feedback and objective measurements of muscle activation. Full article

Co-combustion is regarded as an effective means for high-efficiency utilization of low-quality fuels. However, low-quality fuel has problems such as low energy density and high water content. The fuel quality and blending performance can be further optimized by the pretreatment of low-quality fuel, for example, calorific value, hydrophobicity, and NO conversion rate. Based on the idea of co-upgradation, this study systematically investigates the effects of integrated upgrading on fuel quality and hydrophobicity under different conditions. In this study, lignite and wheat straw were selected as research objects. The co-upgrading experiments of wheat straw and lignite were conducted at reaction temperatures of 170 °C, 220 °C, and 270 °C in flue gas and air atmospheres with biomass blending ratios of 0%, 25%, 50%, 75%, and 100%. SEM (scanning electron microscopy) and nitrogen (N₂) adsorption analyses showed that under low-temperature and low-oxygen conditions, organic components from biomass pyrolysis migrated in situ to cover the surface of lignite, resulting in a gradual smoothing of the fuel surface and a decrease in the specific surface area. Meanwhile, water reabsorption experiments and contact angle measurements showed that the equilibrium water holding capacity and water absorption capacity of the lifted fuels was weakened, and hydrophobicity was enhanced. Combustion kinetic parameters and pollutant release characteristics were investigated by thermogravimetric analysis (TGA) and isothermal combustion tests. It was found that co-upgradation could effectively reduce the reaction activation energy and NO conversion rate. Characterized by Raman spectroscopy (Raman) and X-ray photoelectron spectroscopy (XPS), in situ migration of organic components affected combustion reactivity by modulating changes in N-containing product precursors. The results showed that the extracted fuel with a 75% biomass blending ratio in the flue gas atmosphere exhibited the best overall performance at 220 °C, with optimal calorific value, combustion reactivity, and hydrophobicity. These findings may provide important theoretical foundations and practical guidance for the optimization of industrial-scale upgrading processes of low-quality fuels. Full article

Commercial hydrophobic membranes encounter severe problems such as membrane wetting and membrane fouling under extreme conditions, which affect membrane separation performance. To enhance the anti-fouling abilities of hydrophobic membranes, a composite membrane with omniphobic characteristics was fabricated successfully in this paper. Titanium dioxide (TiO₂) nanoparticles were in-situ grown via the hydrothermal synthesis method, and then fluorosilane with low surface energy was grafted on polyvinylidene fluoride (PVDF) membranes. Subsequently, the morphologies, chemical compositions, wetting properties and structural parameters of composite membranes were characterized systematically. Various contaminants were added to the feed to investigate the anti-fouling and anti-wetting performances of the composite membrane in membrane distillation tests. The results showed that butyl titanate was first hydrolyzed to form titanium hydroxide (Ti(OH)₄) and then it was dehydrated to form TiO₂ in the hydrothermal environment. TiO₂ crystals continued to grow and formed rough morphology with micro-nano synergistic distribution, which is similar to a “sunflower” disk composed of cubic clusters and nanopillars. Meanwhile, fluorosilane successfully was grafted onto TiO₂. The contact angles of deionized water, 0.4 mM sodium dodecyl sulfate (SDS) solution and 0.2% v/v mineral oil emulsion on the composite membrane surface were 167.3°, 162.0° and 158.5°, respectively, endowing the composite membrane with excellent omniphobic features. In direct contact membrane distillation (DCMD) tests, the composite membrane exhibited a relatively stable membrane permeate flux, and the salt rejection rate almost reached 100%. The mixture, consisting of inorganic salts, organic substances, surfactants and oil emulsions, was used as feed. In contrast, the commercial PVDF membrane flux decreased drastically and even dropped to 0 due to the membrane fouling and wetting. As for the pristine PVDF membrane, the membrane surface was covered with pollutants and membrane pores were blocked. Therefore, it was proved that the omniphobic composite membrane possesses outstanding anti-fouling and anti-wetting performance. Full article

Magnetic induction imaging technology, as a non-invasive detection method based on the principle of electromagnetic induction, has a wide range of applications in the field of materials science and engineering with the advantages of no radiation and fast imaging. However, it has not been improved to address the problems of high contact measurement interference and low spatial resolution of traditional strain detection methods in bulk materials engineering. For this reason, this study proposes a magnetic induction detection technique incorporating metal particle assistance and designs a hardware detection system based on an eight-coil sensor to improve the sensitivity and accuracy of strain detection. Through finite element simulation and an image reconstruction algorithm, the conductivity distribution reconstruction was realized. Taking asphalt concrete as the research object, particle-reinforced composite specimens with added metal particles were prepared. On this basis, a hardware detection system with eight-coil sensors was designed and constructed, and the functionality and stability of the system were verified. Using finite element analysis technology, two-dimensional and three-dimensional simulation models were established to focus on analyzing the effects of different coil turns and excitation parameters on the induced voltage signal. The method proposed in this study provides a new technical approach for non-contact strain detection in road engineering and can also be applied to other composite materials. Full article

The harmonic balance method (HBM) is a widely used method for determining the forced response of non-linear systems such as bladed disks. This paper focuses on analyzing the sensitivity of this method to key computational parameters and its robustness. HBM and HBM coupled with pseudo arc length continuation are used in this paper to solve the equation of motion of a test case. The pseudo arc length continuation is necessary because when intermittent contact occurs, natural continuation cannot guarantee solver convergence. Intermittent contact, in addition to turning points, introduces further problems, which are caused by an infinite sequence of decaying, but not zero, Fourier coefficients. This results in the need to oversample the non-linear force time signal to avoid convergence problems. The computational parameters investigated in this paper are the samples per period, which determine the number of points in which the time signal is discretized, and the harmonic truncation order. In addition, the connection of contact parameters, such as friction and contact stiffness, with computational parameters is analyzed. This study shows that the number of time samples per period is the most limiting parameter when intermittent contact occurs; whereas, in the absence of intermittent contact convergence, problems can be avoided with a reasonable number of time points. Poor discretization of the signal leads to a bad computation of Fourier coefficients and thus a lack of convergence. Sensitivity analysis shows that the samples per period depend on the contact parameters, especially normal stiffness. To ensure the solver robustness, it is important to set the computation parameters appropriately to ensure the convergence of the solver while avoiding unnecessary computation effort. Full article