Search Results (316)

Existing force-measuring devices lack versatility in studying the dynamic coupling process between the seedling-picking device and the plug seedling pot during automatic transplanting. This research developed a universal force-measuring device featuring a centrally symmetrical clamping needle layout and a simultaneous insertion and clamping mechanism. The force-measuring device enables the flexible adjustment of the number of clamping needles (2/3/4 needles) via a modular structure. It can also modify the insertion depth and angle of the clamping needles to accommodate three specifications of plug seedlings, namely 50-hole, 72-hole, and 128-hole plug seedlings. A real-time monitoring system with dual pull-pressure sensors is integrated to precisely acquire the dynamic response curves of the clamping force (F_J) and the disengaging force (F_N) of the plug seedling pot during the seedling-picking process. Taking water spinach plug seedlings as the research object and combining with EDEM-RecurDyn coupling simulation, the interaction mechanism between the clamping needle and the plug seedling pot was elucidated. The performance of the force-measuring device was verified through systematic force-measuring experiments. The main research findings are as follows: The force-measuring device designed in this study can successfully obtain the mechanical characteristic curve of the relevant seedling plug pot throughout the automatic seedling-picking process. The simulation results show high consistency with the experimental results, indicating that the force-measuring device can effectively reveal the dynamic coupling process between the seedling-picking device and the plug seedling pot. The verification experiment demonstrates that the force-measuring device can effectively quantify the mechanical properties of the of plug seedling pots under different plug seedlings specifications and different clamping needles configurations. Reducing the hole size and increasing the number of clamping needles can effectively decrease the peak value of the disengaging force (F_Nmax). The peak clamping force (F_Jmax) is approximately inversely proportional to the needle number, with the four-needle layout providing the most uniform force distribution. The force-measuring device developed in this study is functional, applicable, and versatile, offering a general force-measuring tool and a theoretical foundation for optimal seedling-picking device design. Full article

In the face of growing demand for emergency treatment in mass casualty incidents involving acute hemorrhagic shock, disaster sites often suffer from limited search and rescue manpower and inadequate medical detection capabilities. With the rapid development of robot technology, the deployment of robots provides greater flexibility and reliability in disaster emergency response and search and rescue work, which can effectively address the shortage of search and rescue forces and medical resources at disaster sites. This paper introduces a snake-like robot designed for the rapid triage of casualties with hemorrhagic shock. Through a structural design combining active wheels and orthogonal joints, the robot integrates the advantages of high-speed mobility of wheeled robots with the high flexibility of jointed robots so as to adapt to the complex environments typical of search and rescue scenarios. Meanwhile, the end of the robot is equipped with a visible light camera, an infrared camera and a voice interaction system, which realizes the rapid triage of casualties with hemorrhagic shock by collecting visible light, infrared and voice dialog data of the casualties. Through Webots software simulation and outdoor site simulation experiments, seven indicators of the designed snake-like search and rescue robot are verified, including walking speed, minimum passable hole size, climbing angle, obstacle-surmounting height, passable step size, ditch-crossing width and turning radius, as well as the effectiveness of collecting visible light images, infrared images and voice dialog data of the casualties. Full article

A novel, eco-friendly perovskite solar cell design is investigated using numerical simulations based on the finite-difference time-domain (FDTD) method. The proposed structure incorporates a two-dimensional (2D) photonic crystal (PhC) architecture featuring a titanium dioxide (TiO₂) cylindrical electron extraction layer. To reduce fabrication complexity and overall production costs, a hole-transport-layer-free (HTL-free) configuration is employed. Simulation results reveal a significant enhancement in photovoltaic performance compared to conventional planar structures, achieving an ultimate efficiency of 42.3%, compared to 36.6% for the traditional design—an improvement of over 16%. Electromagnetic field distributions are analyzed to elucidate the physical mechanisms behind the enhanced absorption. The improved optical performance is attributed to strong coupling between photonic modes and surface plasmon polaritons (SPPs), which enhances light–matter interaction. Furthermore, the device exhibits polarization-insensitive and angle-independent absorption characteristics, maintaining high performance for both transverse magnetic (TM) and transverse electric (TE) polarizations at incidence angles up to 60°. These findings highlight a promising pathway toward the development of cost-effective, lead-free perovskite solar cells with high efficiency and simplified fabrication processes. Full article

As the demand for clean water continues to rise, the development of reliable and environmentally sustainable purification methods has become increasingly important. In this study, we describe the production and characterization of electrospun polyimide (PID) nanofibers modified with MXene (Ti₃C₂Tx), tungsten trioxide (WO₃), and titanium dioxide (TiO₂) nanomaterials for improved photocatalytic degradation of rhodamine 6G (R6G), a model organic dye. Superior photocatalytic performance was achieved by suppressing electron–hole recombination, promoting efficient charge carrier separation, and the significant increase in light absorption through the addition of metal oxide nanowires and MXene to the PID matrix. Comprehensive characterization confirms a core–shell nanofiber architecture with TiO₂, WO₃, and MXene effectively integrated and electronically coupled, consistent with the observed photocatalytic response. The PID/TiO₂/WO₃/MXene composite exhibited the highest photocatalytic activity among the tested configurations, degrading R6G by 74% in 90 min of light exposure. This enhancement was ascribed to the synergistic interactions between MXene and the metal oxides, which reduced recombination losses and promoted effective charge transfer. The study confirms the suitability of PID-based hybrid nanofibers for wastewater treatment applications. It also points toward future directions focused on scalable production and deployment in the field of environmental remediation. Full article

This study presents a comprehensive numerical investigation of excitonic states in GaAs quantum wells embedded in ${\mathrm{Al}}_x$${\mathrm{Ga}}_{1-x}$As barriers, incorporating the effects of donor and acceptor impurities, external electric and magnetic fields, and varying well widths. The electron and hole wavefunctions are computed by directly solving the Schrödinger equation using the finite element method in cylindrical coordinates, without assuming trial forms. To evaluate the exciton binding energy, the implementation and comparison of two independent approaches were performed: a numerical integration method based on elliptic function corrections, and a novel finite element electrostatic formulation using COMSOL Multiphysics v5.6. The latter computes the Coulomb interaction by solving Poisson’s equation with the hole charge distribution and integrating the resulting potential over the electron density. Both methods agree within 1% and capture the spatial and field-induced modifications in excitonic properties. The results show that quantum confinement enhances binding in narrow wells, while donor impurities and electric fields reduce binding via spatial separation of carriers. Magnetic fields counteract this effect by providing radial confinement. The FEM-based electrostatic method demonstrates high spatial accuracy, computational efficiency, and flexibility for complex heterostructures, making it a promising tool for exciton modeling in low-dimensional systems. Full article

In turbine blade environments, the combination of blade curvature and accelerating flow gives rise to streamwise pressure gradients (SPGs), which substantially impact coolant–mainstream interactions. This study investigates the effect of SPGs on film cooling performance using Large Eddy Simulation (LES) for a shaped cooling hole at a density ratio of $\mathrm{DR}=1.5$ under two blowing ratios: $M=0.5$ and $M=1.6$. Both favorable pressure gradient (FPG) and zero pressure gradient (ZPG) conditions are examined. LES predictions are validated against experimental data in the high blowing ratio case, confirming the accuracy of the numerical method. Comparative analysis of the time-averaged flow fields indicates that, at $M=1.6$, FPG enhances wall attachment of the coolant jet, reduces boundary layer thickness, and suppresses vertical dispersion. Counter-rotating vortex pairs (CVRPs) are also compressed in this process, leading to improved downstream cooling. At $M=0.5$, however, the ZPG promotes greater lateral coolant spread near the hole exit, resulting in superior near-field cooling performance. Instantaneous flow structures are also analyzed to further explore the unsteady dynamics governing film cooling. The Q criterion exposes the formation and evolution of coherent vortices, including hairpin vortices, shear-layer vortices, and horseshoe vortices. Compared to ZPG, the FPG case exhibits a greater number of downstream hairpin vortices identified by density gradient, and this effect is particularly pronounced at the lower blowing ratio. The shear layer instability is evaluated using the local gradient $Ri$ number, revealing widespread Kelvin–Helmholtz instability near the jet interface. In addition, Fast Fourier Transform (FFT) analysis shows that FPG shifts disturbance energy to lower frequencies with higher amplitudes, indicating enhanced turbulent dissipation and intensified coolant mixing at a low blowing ratio. Full article

Achieving a high load-bearing capacity and fatigue life of joints of composite structures is possible with the use of mechanical fasteners. The aim of this research was to search for effective methods of increasing the load-bearing capacity of mechanical joints of CFRP components. A CFRP composite was made from carbon fabric (KORDCARBON, Czech Republic) using vacuum bag technology. Riveted and bolted joints were evaluated. The pressures exerted on the composite parts during assembly were measured. The values of pressures that cause permanent deformation of the tested composite were estimated. It was shown that the onset of failure of riveted joints is related to the pressures of the shanks of these fasteners on the holes. The load capacity of bolted joints also depends on the pressures of bolt heads on the composite elements. The value of bearing stresses in the pivot-loaded composite was determined. A tomographic study was conducted to determine the damage caused by their interaction. It was shown that the application of a rare-earth adhesive between the threaded bolt shank and the hole results in an increase in the load-bearing capacity of bolted joints by about 10%. A similar increase in strength is observed when the bolt assembly torque is increased. Full article

Accurate and timely estimation of soybean emergence at the plot scale using unmanned aerial vehicle (UAV) remote sensing imagery is essential for germplasm evaluation in breeding programs, where breeders prioritize overall plot-scale emergence rates over subimage-based counts. This study proposes PlotCounter, a deep learning regression model based on the TasselNetV2++ architecture, designed for plot-scale soybean seedling counting. It employs a patch-based training strategy combined with full-plot validation to achieve reliable performance with limited breeding plot data. To incorporate additional agronomic information, PlotCounter is extended into a multitask learning framework (MTL-PlotCounter) that integrates sowing metadata such as variety, number of seeds per hole, and sowing density as auxiliary classification tasks. RGB images of 54 breeding plots were captured in 2023 using a DJI Mavic 2 Pro UAV and processed into an orthomosaic for model development and evaluation, showing effective performance. PlotCounter achieves a root mean square error (RMSE) of 6.98 and a relative RMSE (rRMSE) of 6.93%. The variety-integrated MTL-PlotCounter, V-MTL-PlotCounter, performs the best, with relative reductions of 8.74% in RMSE and 3.03% in rRMSE compared to PlotCounter, and outperforms representative YOLO-based models. Additionally, both PlotCounter and V-MTL-PlotCounter are deployed on a web-based platform, enabling users to upload images via an interactive interface, automatically count seedlings, and analyze plot-scale emergence, powered by a multimodal large language model. This study highlights the potential of integrating UAV remote sensing, agronomic metadata, specialized deep learning models, and multimodal large language models for advanced crop monitoring. Full article

Helical milling presents a promising alternative to conventional drilling for hole production, offering superior surface quality and improved production efficiency. While this technique has been extensively applied in the aerospace industry, its potential for machining common engineering materials, such as AISI 1045 steel, remains underexplored in the literature. This study addresses this gap by systematically evaluating the influence of key process parameters—cutting speed (V_c), axial depth of cut (a_p), and tool diameter (D_t)—on hole quality attributes, including surface roughness, burr formation, and nominal diameter accuracy. A full factorial experimental design (2³) was employed, coupled with analysis of variance (ANOVA), to quantify the effects and interactions of these parameters. The results reveal that, with a higher V_c, it is possible to reduce surface roughness (R_a) by 30% to 40%, while an increased a_p leads to a 50% increase in R_a. Additionally, D_t emerged as the most critical factor for nominal diameter accuracy, reducing geometrical errors by 1% with a larger D_t. Burr formation was predominantly observed at the lower end of the hole, highlighting challenges specific to this technique. These findings provide valuable insights into optimizing helical milling for low-carbon steels, offering a foundation for broader industrial adoption and further research. Full article

The dynamics of the vibrational mode of motion of the driving member of a nonideal system, a mixing–whipping device based on a simple slide-crank mechanism, was studied. The highly nonlinear differential equations of motion were solved numerically by the Runge–Kutta method. The interaction of the mixing–whipping device with the nonideal excitation source causes the rotational speed of the engine shaft and the rotation angle of the driving member to fluctuate, accomplishing a damped process. The parameters of the device and the nonideal energy source have an effect on the kinematic, vibrational and energy characteristics of the system. An increase in the engine’s torque, crank length, number and radius of piston holes, and piston mass, as well as a decrease in the fluid’s density, leads to a reduction in the oscillation range of the crank angle, amplitude and period of angular velocity oscillations of the engine shaft and the mixing–whipping force power. The effects of a nonideal energy source may be used in designing a mixing–whipping device based on a slider-crank mechanism to select effective system parameters and an energy-saving motor in accordance with the requirements of technological processes and products. Full article

A strong interaction between Bi³⁺ and ZnO was used to successfully sensitize ZnO nanorods with quantum dots (QDs) of Bi₂O₃ through three different strategies. Although the Bi₂O₃ QDs had similar particle size distributions, their photocatalytic performance varied significantly, prompting the investigation of factors beyond particle size. The study revealed that the photochemical method selectively deposited Bi₂O₃ QDs onto electron-rich ZnO sites, providing a favorable pathway for efficient electron–hole separation and transfer. Consequently, abundant h⁺ and ·OH radicals were generated, which effectively degraded Rhodamine B (RhB). As demonstrated in the RhB degradation experiments, the Bi₂O₃/ZnO nanorod catalyst achieved an 89.3% degradation rate within 120 min, significantly outperforming catalysts with other morphologies. The photoluminescence (PL) and time-resolved photoluminescence (TRPL) results indicated that the Bi₂O₃/ZnO heterostructure constructed an effective interface to facilitate the spatial separation of photogenerated charge carriers, which effectively prolonged their lifetime. The electron paramagnetic resonance (EPR) results confirmed that the ·OH radicals played a key role in the degradation process. Full article

To address the difficulty of locating small-hole leaks in buried natural gas pipelines, this study conducted a comprehensive theoretical and numerical analysis of the acoustic characteristics associated with such leakage events. A coupled flow–acoustic simulation framework was developed, integrating gas compressibility via the realizable k-ε and Large Eddy Simulation (LES) turbulence models, the Peng–Robinson equation of state, a broadband noise source model, and the Ffowcs Williams–Hawkings (FW-H) acoustic analogy. The effects of pipeline operating pressure (2–10 MPa), leakage hole diameter (1–6 mm), soil type (sandy, loam, and clay), and leakage orientation on the flow field, acoustic source behavior, and sound field distribution were systematically investigated. The results indicate that the leakage hole size and soil medium exert significant influence on both flow dynamics and acoustic propagation, while the pipeline pressure mainly affects the strength of the acoustic source. The leakage direction was found to have only a minor impact on the overall results. The leakage noise is primarily composed of dipole sources arising from gas–solid interactions and quadrupole sources generated by turbulent flow, with the frequency spectrum concentrated in the low-frequency range of 0–500 Hz. This research elucidates the acoustic characteristics of pipeline leakage under various conditions and provides a theoretical foundation for optimal sensor deployment and accurate localization in buried pipeline leak detection systems. Full article

Using the s-d model and Green’s function theory, we investigated for the first time the electron and hole doping effects on the magnetic and optical properties of the double perovskites ${\mathrm{Ba}}_2{\mathrm{FeMoO}}_6$ (BFMO) and ${\mathrm{Sr}}_2{\mathrm{FeMoO}}_6$ (SFMO). Our aim was to find the doping ions that lead to an increase in Curie temperature $T_C$. On the basis of a competition mechanism between spin exchange and s-d interactions, we explain at a microscopic level the decrease in magnetization M and band gap energy $E_g$, as well as the increase in $T_C$ of BFMO and SFMO through substitution with rare earth ions at the Ba(Sr) sites. The influence of doping with K at the Ba(Sr) and Co at the Fe sites on the magnetic properties and the band gap is also discussed. A very good qualitative coincidence with the existing experimental data was observed. Moreover, we found that both M and $T_C$ decrease with decreasing the size of BFMO and SFMO nanoparticles. Full article

This study explored the effects of adding a newly developed type of polydextrose on the appearance, sensory score, and textural parameters of steamed bread and the microstructure of dough, as well as the pasting, thermal, and thermal mechanical properties of high-gluten wheat flours. The results revealed that, compared with a control sample, 3–10% of polydextrose addition significantly increased the hardness, adhesiveness, gumminess, and chewiness of steamed bread, but other textural parameters like springiness, cohesiveness, and resilience remained basically the same. Further, in contrast to the control sample, 3–10% polydextrose addition significantly reduced the specific volume and width/height ratio of steamed bread but increased the brightness index, yellowish color, and color difference; improved the internal structure; and maintained the other sensory parameters and total score. Polydextrose addition decreased the peak, trough, final, breakdown, and setback viscosity of the pasting of wheat flour suspension solutions but increased the pasting temperature. Polydextrose additions significantly reduced the enthalpy of gelatinization and the aging rate of flour paste but increased the peak temperature of gelatinization. A Mixolab revealed that, with increases in the amount of added polydextrose, the dough’s development time and heating rate increased, but the proteins weakened, and the peak torque of gelatinization, starch breakdown, and starch setback torque all decreased. Polydextrose additions increased the crystalline regions of starch, the interaction between proteins and starch, and the β-sheet percentage of wheat dough without yeast and of steamed bread. The amorphous regions of starch were increased in dough through adding polydextrose, but they were decreased in steamed bread. Further, 3–10%of polydextrose addition decreased the random coils, α-helixes, and β-turns in dough, but the 3–7% polydextrose addition maintained or increased these conformations in steamed bread, while 10% polydextrose decreased them. In unfermented dough, as a hydrogel, the 5–7% polydextrose addition resulted in the formation of a continuous three-dimensional network structure with certain adhesiveness and elasticity, with increases in the porosity and gas-holding capacity of the product. Moreover, the 10% polydextrose addition further increased the viscosity, freshness, and looseness of the dough, with smaller and more numerous holes and indistinct boundaries between starch granules. These results indicate that the 3–10% polydextrose addition increases the chewiness and freshness of steamed bread by improving the gluten network structure. This study will promote the addition of polydextrose in steamed bread to improve shelf-life and dietary fiber contents. Full article

Occupied and unoccupied electronic states of altermagnetic MnTe(0001) single crystals were studied by photoemission and inverse-photoemission spectroscopies after establishing a reproducible surface cleaning procedure involving repeated sputtering and annealing cycles. The angle-resolved photoemission spectroscopy (ARPES) exhibited a hole-like band dispersion centered at the $\overline{\mathsf{\Gamma }}$ point, which was consistent with the reported ARPES results and our density functional theory (DFT) calculations with the on-site Coulomb interaction U. The observed Mn 3d↑-derived peak at −3.5 eV, however, significantly deviated from the DFT + U calculations. Meanwhile, the Mn 3d↓-derived peak at +3.0 eV observed by inverse-photoemission spectroscopy agreed well with the DFT + U results. Based on simulations of the spectral function employing an w-dependent model self-energy, we found significant relaxation effects in the electron-removal process, while such effects were negligible in the electron-addition process. Our study provides a comprehensive picture of electronic states, forming a solid foundation for understanding the magnetic and transport properties of MnTe. Full article