Search Results (531)

“Interbedded water in thin coal seams” is characterized by its high degree of concealment and complex hydraulic connections. However, due to the confined space of underground mine tunnels and severe electromagnetic interference from metal structures, traditional geophysical methods struggle to accurately delineate the boundaries of water accumulation, making this a major and challenging water hazard in coal mines. Taking the Qinhua Coal Mine in Xinjiang, China, as the engineering context, this paper investigates the detection of water accumulation in interbedded coal seams within goaf areas using the cross-hole resistivity method. It proposes a cross-hole resistivity tomography scanning approach characterized by “progressive depth penetration and layer-by-layer traversal,” and employs an inversion method based on inequality constraints to obtain relatively detailed and reliable imaging results. Through resistivity imaging analysis, low-resistivity water accumulation anomalies were successfully delineated, and water accumulation dead zones were identified. Based on the detection results, effective drainage was carried out beneath the water-filled zones. Subsequent follow-up surveys confirmed the disappearance of the low-resistivity anomalies, thereby validating the reliability and engineering practicality of the cross-hole resistivity tomography method for precisely detecting water body boundaries under complex geological conditions in coal seams. Full article

To address the challenge of hand intrusion detection in frozen tuna cutting operations where operators wear thermal-insulating gloves, this study proposes a hand detection method based on dual-domain background modeling with absolute accuracy constraints. To tackle issues arising from low-resolution infrared arrays, such as defective pixels, random noise, and complex low-temperature backgrounds, a data preprocessing pipeline integrating defective pixel correction, exponential moving average (EMA), and median filtering is developed. A dual-domain background suppression (DDBS) strategy, combining spatial-domain and temporal-domain models with sensor absolute accuracy constraints, is employed to extract hand foregrounds under complex thermal conditions. Temperature thresholding, connected-component analysis, and hole-filling are further applied to effectively separate hands from frozen tuna. An experimental platform incorporating a Raspberry Pi 4B and an MLX90640 sensor was constructed, and a dataset comprising 1173 infrared frames was collected for validation purposes. Experimental results demonstrate that the proposed method achieves an accuracy of 94.12%, precision of 91.69%, recall of 97.55%, and F1-score of 94.53% for hand intrusion detection, with an average processing time of approximately 1.84 ms per frame. This provides a cost-effective, real-time solution for hand safety monitoring in frozen food processing operations. Full article

To address the difficulty of real-time detection of seed-filling performance in pneumatic suction seed metering devices under high-speed operation—where seed targets are tiny, prone to adhesion, and affected by motion blur—this paper proposes a lightweight online detection algorithm, YOLOv8n-MA. First, according to the seed adsorption characteristics of the suction holes, the detection targets are divided into three categories: none, one, and two. Second, based on YOLOv8n, the backbone network is replaced with MobileNetV1 to reduce computational cost, and an ACmix attention module is integrated into the Neck to enhance feature representation for the three suction-hole states. Finally, to meet the demand for low-latency inference on resource-constrained devices, the model is deployed on an edge computing controller to achieve real-time detection. Experimental results show that, compared with the original YOLOv8n, the parameters and FLOPs of YOLOv8n-MA are reduced by 34.4% and 59.8%, respectively, while the mean average precision (mAP) is improved by 2.0% to 96.8%, achieving a superior trade-off between accuracy and efficiency over other detection models of the same category, such as YOLOv5n, YOLOv9n, and YOLOv10n. In field tests, the detection accuracy reaches 95.02% at 12 km/h and 92.65% at 15 km/h. The proposed method provides effective technical support for the intelligent monitoring and control of precision seeding under high-speed operation. Full article

Understanding the finishing behavior of hybrid structures produced by additive manufacturing based on FDM is critically important in systems where phases with different thermal and mechanical properties coexist. In this study, the drilling performance of hybrid structures with a PLA/17-4 PH/PLA layer arrangement was comprehensively investigated in terms of thrust force, moment, surface roughness, temperature variation, vibration behavior, and surface integrity. For this purpose, a total of 16 drilling tests were performed on 56 × 56 × 15 mm hybrid specimens with 100% infill density, in a full factorial configuration, at cutting speeds (V) of 80–170 m/min and feed rates (f) of 0.04–0.16 mm/rev. The middle layer was used in the as-printed green state as a 17-4 PH metal-filled filament containing metal particles and binder, without any debinding or sintering step. The results showed that increasing feed rate increased thrust force, moment, and surface roughness in all layers, whereas increasing cutting speed decreased these values and promoted a more stable drilling regime. The middle 17-4 PH layer exhibited lower surface roughness than the outer PLA layers, while thermal measurements indicated limited variation at the hole entrance and higher temperature accumulation at the hole exit. The most favorable drilling condition within the studied hybrid configuration was obtained at 170 m/min and 0.04 mm/rev, whereas the least favorable condition was obtained at 80 m/min and 0.16 mm/rev. Overall, the combination of high cutting speed and low feed rate provided the most suitable drilling window for the studied hybrid structure. The findings also indicated that surface quality was more strongly associated with cutting load and high-frequency vibration components than with vibration level alone. Full article

High-velocity multi-projectile impacts from accidental external debris (e.g., uncontained engine debris or runway stones) on the liquid-filled fuel tanks of modern unmanned aerial vehicles (UAVs) induce complex Fluid–Structure Interaction (FSI) and Hydrodynamic Ram (HRAM) effects, resulting in highly complex dynamic response mechanisms. This study combines high-velocity impact tests with Three-Dimensional Digital Image Correlation (3D-DIC) technology and employs FSI finite element simulations based on the Structured Arbitrary Lagrangian–Eulerian (S-ALE) algorithm to thoroughly investigate the dynamic response mechanisms of liquid-filled containers penetrated by dual projectiles under different spatial spacings and temporal intervals. The results indicate that variations in the spatiotemporal parameters of dual projectiles significantly reconstruct the fluid load field: small spacing and short temporal intervals induce strong wave interference and superposition, generating an amplified composite loading effect that causes a sharp increase in target plate impulse and deformation energy. Conversely, small spacing and long temporal intervals trigger a significant “cavity shielding” phenomenon, causing the subsequent projectile to travel through the existing cavity, which massively suppresses the effective generation of its load and energy transfer. Furthermore, fluid displacement induced by cavity intersection generates secondary pressure waves; the petal hole evolution of the rear plate is dictated by the formation of plastic hinge lines, presenting four typical deformation modes—oblique cross, normal cross, asymmetric pentagon, and hexagon—depending on the degree of spatiotemporal coupling. This study reveals the laws governing the enhanced HRAM effect of dual projectiles, providing key theoretical support for the lightweight protection design and crashworthiness evaluation of long-endurance commercial UAV fuel tanks. Full article

This study assesses the possibility of identifying non-through defects in dielectric coatings, specifically interfacial defects located at the metal–coating boundary, by means of high-voltage non-destructive testing. It is demonstrated that partial discharges causing characteristic distortions of the applied test-voltage pulse can be used as a reliable diagnostic feature of such defects. Using an equivalent capacitive representation of a defective coating, a relationship is established between the apparent charge and the geometry of the air-filled gap. The proposed approach is supported by COMSOL simulations of the electric-field distribution and by experiments performed on Plexiglas specimens containing blind holes of different depths. In addition, a method is developed for isolating the partial-discharge signal based on a weighted sum of increments in the root-mean-square deviations of the second derivative of the voltage waveform. The resulting relationships enable estimation of the residual coating thickness in the defect region. Full article

Peach bacterial shot hole is a major disease limiting the yield and quality in most peach-producing areas worldwide. To clarify its etiology and support the development of targeted management strategies, diseased samples were collected from Changli County peach orchards. The pathogen was isolated, purified and verified by Koch’s postulates. Based on morphological, biochemical and multi-locus phylogenetic analyses, the causal agent was identified as Xanthomonas arboricola pv. pruni (isolate TCK-5). Biological characterization revealed that TCK-5 grew optimally in KB and NB medium at 28 °C, pH 7.0–7.5 and 0.5–1.0% NaCl, efficiently utilized glycerol and organic nitrogen source (proteose peptone, beef extract and yeast extract), with light showing no significant effect on growth. The strain TCK-5 exhibited a lethal temperature of 51 °C, indicating that heat treatment above this threshold effectively disinfects pruning tools and contaminated plant debris. Among 18 bactericides tested in vitro, biological bactericide outperformed chemical ones, with 0.3% Tetramycin AS (EC₅₀ = 0.1051 mg/L) and 3% Zhongshengmycin SL (EC₅₀ = 2.9252 mg/L) exhibiting the strongest inhibitory activity. This study fills a regional knowledge gap in the epidemiological distribution of the pathogen in northern China and advances current understanding of X. arboricola pv. pruni occurrence, providing a scientific basis for subsequent epidemic monitoring and integrated control of peach bacterial shot hole. Full article

Different from isothermal amplification, for polymerase chain reaction (PCR), highly reliable valving for PCR chamber, significantly shortened thermal cycling time, and concise multiplexed detection are always challenges for microfluidic-based devices. Here, we present a real-time, centrifugal, plastic microfluidic chip for multiplexed PCR detection specifically based on the mechanism of cooperating valving. To achieve consistent amplification, a concise dual-valving strategy was developed. Instantly melted wax is centrifuged and completely filled into the narrow channel and hole to act as the compact wax valve. Meanwhile, an elastic and sticky membrane is depressed to seal the hole to act as the membrane valve. The wax valve is protected by the membrane valve from being damaged by both mechanical deformation and thermal corroding caused by the hot vapor with high pressure from the PCR chamber. A double-sided heating strategy is adopted to reduce the thermal cycling time; meanwhile, a balanced mechanism is used to achieve real-time amplification by rotating the centrifugal chip between the heating and detection positions in turn. As a proof-of-concept, the performance of the centrifugal chip with four parallel units is demonstrated by successfully detecting purified DNA templates or the extracted DNA templates from cells as well within 20 min. Full article

Conventional solid-inlay lubrication research has focused on the overall inlay layout and generalized lubrication effects; localized inlay lubrication enables precise release of the lubricant and rapid formation of a uniform and dense lubricant film. The aim of this study is to use a combination of simulations and experimentation to establish a localized spherical friction pair containing a filled-hole structure, so that optimal lubrication can be predicted accurately. We designed seven different kinds of localized annular band inlay axial tiles, with ratios of 10, 12, 15, 18, 20, 22, and 25; carried out a transient mechanical analysis through finite element software, comparing the equivalent stress and friction coefficient of the inlay tiles with different ratios; and conducted friction wear tests through a self-developed spherical wear test bench. The friction surfaces of the tested specimens were analyzed for sliding friction coefficients and wear, as well as by SEM surface and EDS analyses. The results show that the best mechanical properties and the smallest theoretical friction coefficients are obtained when the relative ratio of the ring diameter to inlay hole diameter is 25. This study provides a theoretical basis for the design of spherical solid-inlay lubrication structures in the region of the split-belt ring design. Full article

Lead-free perovskite solar cells have become promising materials in the solar energy field; however, there are some constraints limiting their efficiency, like unfavorable band alignment, high defect densities, and inefficient charge extraction. Cs₃Sb₂I₉ is a lead-free material that has excellent stability, but its experimentally reported efficiencies remain low (<4%). Therefore, Cs₃Sb₂I₉ device performance was investigated using the one-dimensional Solar Cell Capacitance Simulator (SCAPS-1D), where the planar n–i–p structure was analyzed, focusing on its band alignment, transport layers, and key device parameters. The optimized device achieved a power conversion efficiency (PCE) of 13.62%, an open circuit voltage (Voc) of 1.37 V, a short circuit current density (Jsc) of 11.77 mA/cm², and a fill factor (FF) of 84.15% with a 180 nm PCBM electron transport layer, a 150 nm Cu₂O hole transport layer, and a 500 nm absorber thickness. This study advances the development of efficient lead-free perovskite solar cells, promoting sustainable and clean energy. Full article

The long-term safety of rockfill dams is critically dependent on the quality of the filling material. Therefore, it is essential to predict the blasting grading distribution scientifically and accurately. This paper proposes an engineering-scale numerical simulation method to predict the grading distribution of hydraulic-grade rockfill material and verify its effectiveness through major hydropower engineering applications. Firstly, based on the mechanical mechanism of rock fragmentation and relevant experimental data, the critical blasting damage threshold for rock detachment is determined. Then, the threshold is used to identify the boundaries of blasted rock blocks, enabling the quantitative derivation of grading curves. The method is applied to simulate the blasting mining of fill materials at the Lianghekou Hydropower Station. A comparison with field screening data demonstrates that the method effectively simulates the spatial distribution of blast-induced block sizes. Furthermore, numerical simulations investigate the influence of hole arrangements and delay times on fragmentation. The results indicate a significant difference in the grading distribution characteristics between rectangular and staggered hole arrangements, with the rectangular arrangement conducive to producing a continuously non-uniform gradation. Delay time also markedly impacts fragmentation, primarily affecting the distribution of medium and large-sized blocks. The mean fragment size initially decreases and then gradually increases with longer delay times. Full article

Organic-type solar cells containing an active layer of block copolymer donor PTB7-Fx (x = 0, 20, and 100), based on benzo [1,2-b:4,5-b’]dithiophene and variably fluorinated thieno [3,4-b]thiophene units, and fullerene acceptor [6,6]phenyl-C₇₁-methylbutyrate, were constructed. The active layer thin film of the solar cells was obtained from a dichlorobenzene solution at an established concentration via spin-coating of the donor–acceptor mixture in the presence of solvent additives such as 3% diiodooctane and 1% triethyl phosphate. Organic photovoltaic elements with normal device architecture were prepared on glass substrates using an indium tin oxide anode, a spin-coated hole transporting layer of poly(ethylene dioxythiophene):polystyrenesulfonate, the aforementioned active layer, followed by an electron transporting layer of zinc oxide nanoparticles, and finally a magnetron sputtered silver (Ag) top-electrode. The optical properties, thin film morphology, and the thickness of the active layers were investigated. Additionally, current density–voltage characteristics and impedance spectra of photovoltaic devices were measured. It was found that PTB7-Fx:PC₇₁BM-based solar cells processed in the presence of two types of solvent additives, diiodooctane and triethyl phosphate, with a sputtered Ag top-electrode display similar absorption and quantum efficiency spectra, as well as comparable current density–voltage characteristics and efficiencies to the same devices fabricated without additives. The diiodooctane solvent additive preferably dissolves the fullerene component and has a positive effect on fill factor enhancement, impedance spectra improvement, and amelioration in charge carrier transport and collection, whereas the triethyl phosphate solvent additive preferentially dissolves the copolymer donor and has a more pronounced impact on the refined morphology of the thin film active layers. Full article

Using low-pressure cold spray technique, Fe-Al composite coatings with different Al contents were applied to the surface of 45 steel to improve its corrosion resistance in chloride-containing settings. The microstructure, mechanical characteristics, and electrochemical corrosion behavior of the coatings were thoroughly examined in relation to the Al content (2, 4, 6, and 8 wt.%). The findings show that the microhardness of the composite coating decreases monotonically (from 157.98 HV to 99.29 HV) as the Al content rises because of the increased proportion of the soft phase; in contrast, the porosity and corrosion current density show a pattern of first decreasing and then increasing. The coating porosity was reduced to a minimum (1.37%) when the Al concentration reached 6 wt.% because the soft Al particles experienced enough plastic flow to fill the holes in the hard Fe matrix. The 6Al composite coating demonstrated the best electrochemical protection performance in a 3.5 wt.% NaCl solution, with the lowest corrosion current density (2.237 × 10⁻⁴ A/cm²) and the strongest interfacial charge transfer resistance. The synergistic corrosion protection mechanism comprising significantly densified physical shielding and microgalvanic sacrificial anode protection by the active Al phase was clarified in this study. The ideal composition ratio for this system was determined to be 6 wt.% Al by carefully matching the coating’s mechanical load-bearing needs with long-term corrosion prevention goals. Full article

Objective: The aim of this study will be to evaluate the effectiveness of a task-oriented training program in improving functional performance and health outcomes in patients with MS. Methods: A pilot randomized clinical trial will be conducted according to SPIRIT guidelines. Participants will be randomly assigned to the experimental group or the control group. Assessment and treatment will take place at patient association facilities or research center. Participants diagnosed with MS by a neurologist and meeting the inclusion criteria will be invited to participate voluntarily. The experimental group will undergo an 8-week TOT intervention, twice weekly, 45 min. The control group will maintain usual care and be given a fatigue management pamphlet. The main variable in this study will be the Canadian Occupational Performance Measure. The level of fatigue will be assessed with the Modified Impact Fatigue Scale and the Fatigue Severity Scale, upper limb strength using the Arm Curl Test, hand and pinch dynamometer, motor speed with the Finger Tapping Test, manual dexterity with the Nine Hole Peg Test, Purdue Pegboard Test and the Coin Rotation Test. Satisfaction and adherence with the intervention will be recorded with the Sport Injury Rehabilitation Adherence Scale. Results: The results will be published as a peer-reviewed article. Conclusions: The present protocol aims to fill a relevant gap in the literature, offering a structured intervention based on task-oriented training principles, specifically tailored to the functional and occupational needs of people with MS. Full article

To address the severe multiple-seed pickup problem during the seed-filling process of an air-suction seed metering device for small-seed crops with multiple seeds per hill, a combined seed-cleaning mechanism consisting of an upper seven-tooth seed-cleaning device and a lower seed-cleaning blade was developed based on an analysis of the causes of multiple pickup. Mathematical models of seed motion and force were established to describe the interaction between the seven-tooth seed-cleaning device and the seed population during the cleaning process. The installation position and adjustment mechanism of the device on the seed chamber housing were determined, and its tooth-profile parameters and major operating positions were theoretically analyzed. Accordingly, the design method and calculation models for the key parameters of the seven-tooth seed-cleaning device were established. A quadratic regression orthogonal rotational combination experiment was conducted using three factors affecting cleaning performance: the distance between the apex of the first tooth and the corresponding suction hole, the operating speed of the seed metering device, and the negative pressure. Regression equations were established and response surface analysis was performed. With the seed-cleaning qualification rate as the optimization objective, the optimal parameter combinations were obtained as follows: for millet, 3.36 mm, 3.59 km/h, and 1.43 kPa; for broomcorn millet, 3.49 mm, 4.22 km/h, and 2.11 kPa; and for rapeseed, 3.15 mm, 3.73 km/h, and 1.52 kPa. To reduce the influence of random error, 200 repeated bench tests were conducted for each seed type under its corresponding optimal parameter combination at operating speeds of 2.0–5.0 km/h. The seed-cleaning qualification rates for millet, broomcorn millet, and rapeseed were all above 90%, meeting the design requirements of the seed-cleaning mechanism. This study provides a theoretical basis and technical reference for seed-cleaning mechanisms for air-suction precision seed metering devices for small-seed crops with multiple seeds per hill. Full article