Search Results (1,149)

Vessel detection technology based on marine remote sensing imagery is of great importance. However, it often faces challenges, such as small vessel targets, cloud occlusion, insufficient data volume, and severely imbalanced class distribution in datasets. These issues result in conventional models failing to meet the accuracy requirements for practical applications. In this paper, we first construct a novel remote sensing vessel image dataset that includes various complex scenarios and enhance the data volume and diversity through data augmentation techniques. Secondly, we address the class imbalance between foreground (small vessels) and background in remote sensing imagery from two perspectives: the sensitivity of IoU metrics to small object localization errors and the innovative design of a cost-sensitive loss function. Specifically, at the dataset level, we select vessel targets appearing in the original dataset as templates and randomly copy–paste several instances onto arbitrary positions. This enriches the diversity of target samples per image and mitigates the impact of data imbalance on the detection task. At the algorithm level, we introduce the Normalized Wasserstein Distance (NWD) to compute the similarity between bounding boxes. This enhances the importance of small target information during training and strengthens the model’s cost-sensitive learning capabilities. Ablation studies reveal that detection performance is optimal when the weight assigned to the NWD metric in the model’s loss function matches the overall proportion of small objects in the dataset. Comparative experiments show that the proposed NWD-YOLO achieves Precision, Recall, and ${\mathrm{AP}}_{50}$ scores of 0.967, 0.958, and 0.971, respectively, meeting the accuracy requirements of real-world applications. Full article

In the Internet of Things (IoT) era, the demand for cost-effective, flexible, wearable antennas and circuits has been growing. Accordingly, screen-printing techniques are becoming more popular due to their lower costs and high-volume manufacturing. This paper presents and investigates a full-screen-printed 1 × 4 Quasi-Yagi-Uda antenna array on a high-transparency flexible Zeonor thin-film substrate for emerging 26 GHz band (24.25–27.55 GHz) 5G applications. As part of this study, screen-printing implementation rules are developed by properly managing ink layer thickness on a transparent flexible Zeonor thin-film dielectric to achieve a decent antenna array performance. In addition, a screen-printing repeatability study has been carried out through a performance comparison of 24 antenna array samples manufactured by our research partner from CEA-Liten Grenoble. Despite the challenging antenna array screen printing at higher frequencies, the measured results show a good antenna performance as anticipated from the traditional subtractive printed circuit board (PCB) manufacturing process using standard substrates. It shows a wide-band matched input impedance from 22–28 GHz (i.e., 23% of relative band-width) and a maximum realized gain of 12.8 dB at 27 GHz. Full article

Background: The early repolarization pattern (ERP) on electrocardiography (ECG) has been associated with an increased risk of ventricular arrhythmias in susceptible individuals. This study aimed to evaluate the impact of exercise on echocardiographic parameters to explore the potential influence of ERP on hemodynamic response. Methods: Twenty-five healthy, young males with ERP (ERP+ group) and 25 age-matched healthy males without ERP (ERP− group) were enrolled. Comprehensive transthoracic echocardiography was performed at rest and during the early recovery phase following a treadmill exercise test. Baseline values and exercise-induced changes in both conventional and strain-derived echocardiographic parameters were analyzed and compared between groups. Results: Anthropometric measures and resting vital signs were similar in both groups. At baseline, the ERP+ group had a shorter QRS duration. Both groups demonstrated excellent cardiovascular fitness, with comparable chronotropic and pressor responses to exercise. Resting and early recovery-phase echocardiographic parameters were largely similar between ERP+ and ERP− individuals, with no overt structural or functional abnormalities observed in either group. However, ERP+ individuals showed significantly greater reductions in left ventricular end-diastolic volume and stroke volume following exercise, suggesting a distinct volumetric response to physical stress. Conclusions: ERP in healthy young males is not associated with structural cardiac abnormalities or overt myocardial dysfunction. The observed exercise-induced volumetric changes may indicate subtle differences in hemodynamic adaptation, warranting further investigation. Full article

Early detection of ossification of the posterior longitudinal ligament (OPLL) is hampered by the late onset of neurological symptoms, so we built and validated an interpretable machine learning model to identify OPLL during routine health examinations. We retrospectively analyzed 1442 Japanese adults screened between 2020 and 2023, including 432 imaging-confirmed cases, after median imputation, one-hot encoding, Random Forest feature selection that reduced 235 variables to 20, and class-balance correction with SMOTE. Logistic regression, Random Forest, Gradient Boosting, and XGBoost models were tuned using a 5-fold cross-validated grid search, in which a re-estimated logistic regression yielded odds ratios for clinical interpretation. The logistic model achieved 65% accuracy and an AUROC of 0.69 (95% CI 0.66–0.76), matching tree-based models, yet with fewer false-negatives. Advanced age (OR 1.60, 95% CI 1.27–2.00) and elevated CA19-9 (OR 1.24, 95% CI 1.00–1.35) independently increased OPLL odds. This concise, explainable tool could facilitate early recognition of OPLL, reduce unnecessary follow-up, and enable timely preventive interventions in high-volume screening programs. Full article

Objectives: This randomized controlled trial investigated the effects of an 8-week, volume-equated eccentric training program comprising Nordic hamstring and reverse Nordic exercises performed either once or twice per week on measures of physical fitness in pubertal male soccer players. Methods: A total of 34 participants were randomly assigned into a 1-day (n = 16; age = 14.58 ± 0.28 years) or 2-day (n = 18; age = 14.84 ± 0.22 years) per week training group. Physical fitness was assessed using 5 m and 10 m sprints, the 505 change in direction (CiD) speed test, Y-shaped agility test, countermovement jump (CMJ), and standing long jump (SLJ). Results: Significant group-by-time interactions were observed for the 505 CiD test, agility, and CMJ performance (effect sizes [ES] = 0.80 to 1.13). However, no significant interactions were found for the 5 and 10 m sprints or for SLJ (p > 0.05). Compared to the 1-day group, the 2-day training group showed greater improvements in CiD speed (∆7.36%; p < 0.001; ES = 0.92), agility (∆7.91%; p < 0.001; ES = 1.68), and CMJ (∆7.44%; p < 0.01; ES = 0.35), while no differences were observed in 5 and 10 m linear sprints or SLJ performance. According to individual response analysis, improvements across the physical fitness parameters beyond the smallest worthwhile change (SWC_0.2) were observed in 22–83% of players in the 1-day group and 77–100% in the 2-day group. Conclusions: In summary, the findings suggest that when training volume is matched, distributing the eccentric training regimen over two days per week may lead to greater improvements in CiD speed, agility, and CMJ performance compared to a single-day approach. Full article

3D (three-dimensional) property volume is an important data carrier for 3D land administration by using 3D cadastral technology, which can be used to express the legal space (property rights) scope matching with physical entities such as buildings and land. A 3D property volume is represented by a dense set of 3D coordinate points arranged in a predefined order and is displayed alongside the parcel map for reference and utilization by readers. To store a 3D property volume in the database, it is essential to record the connectivity relationships among the original 3D coordinate points, the associations between points and lines for representing boundary lines, and the relationships between lines for defining surfaces. Only by preserving the data structure that represents the relationships among points, lines, and surfaces can the 3D property volume in a parcel map be fully reconstructed. This approach inevitably results in the database storage volume significantly exceeding the original size of the point set, thereby causing storage redundancy. Consequently, this paper introduces a reversible 3D property volume compression coding method (called 3DPV-CC) to address this issue. By analyzing the distribution characteristics of the coordinate points of the 3D property volume, a specific rule for sorting the coordinate points is designed, enabling the database to have the ability of data storage and recovery by merely storing a reordered point set. The experimental results show that the 3DPV-CC method has excellent support capabilities for 3D property volumes of the vertical and slopped types, and can compress and restore the coordinate point set of the 3D property volume for drawing 3D parcel maps. The compression capacity of our method in the test is between 23.66% and 38.42%, higher than the general data compression methods (ZIP/7Z/RAR: 8.37–10.32%). By means of this method, land or real estate administrators from government departments can store 3D property volume data at a lower cost. This is conducive to enhancing the informatization level of land management. Full article

Improper regulation of sugarcane feed volume can lead to harvester inefficiency or clogging. Accurate recognition of feed volume is therefore critical. However, visual recognition is challenging due to sugarcane stacking during feeding. To address this, we propose YOLO-ASM (YOLO Accurate Stereo Matching), a novel detection method. At the target detection level, we integrate a Convolutional Block Attention Module (CBAM) into the YOLOv5s backbone network. This significantly reduces missed detections and low-confidence predictions in dense stacking scenarios, improving detection speed by 28.04% and increasing mean average precision (mAP) by 5.31%. At the stereo matching level, we enhance the SGBM (Semi-Global Block Matching) algorithm through improved cost calculation and cost aggregation, resulting in Opti-SGBM (Optimized SGBM). This double-cost fusion approach strengthens texture feature extraction in stacked sugarcane, effectively reducing noise in the generated depth maps. The optimized algorithm yields depth maps with smaller errors relative to the original images, significantly improving depth accuracy. Experimental results demonstrate that the fused YOLO-ASM algorithm reduces sugarcane volume error rates across feed volumes of one to six by 3.45%, 3.23%, 6.48%, 5.86%, 9.32%, and 11.09%, respectively, compared to the original stereo matching algorithm. It also accelerates feed volume detection by approximately 100%, providing a high-precision solution for anti-clogging control in sugarcane harvester conveyor systems. Full article

Deep hole trepanning of large-diameter titanium alloy rods presents several challenges, including chip breaking, chip clogging, tool wear, and chipping. To address these issues, an optimized multi-tooth trepanning design was developed. An L9 orthogonal experimental array was employed to assess the influence of cutting speed, feed rate, and cutting fluid pressure on the chip volume ratio and to determine optimal process parameters. Results indicate that the impact of process parameters on the chip volume ratio of the first and third cutting teeth follows the order of cutting speed, feed rate, and cutting fluid pressure. Optimal chip morphology for internal chip removal is achieved with a cutting speed of 63.3 m·min⁻¹, a feed rate of 0.18 mm·r⁻¹, and a cutting fluid pressure of 4 MPa. Conversely, improper parameter matching can result in numerous long spiral chips, causing adhesive wear, diffusion wear of the multi-tooth drill, and severe chipping of the cutting edge. Full article

Background: Salmonella infections impose a substantial global health burden, with an estimated 95.1 million cases occurring annually. Pregnant women exhibit a heightened vulnerability due to pregnancy-specific immune adaptations and dietary habits that increase their risk of Salmonella exposure, facilitating possible damage to the placental barrier. Despite this significant burden, Salmonella-associated placental pathology remains poorly understood, particularly its impact on foetal development through microstructural alterations. Aim: This study utilised stereology to assess histomorphological and functional alterations in term placentae of Salmonella Typhi-exposed placentae, compared to unexposed controls. Methods: A hospital-based case-control study was conducted in Ghana. Of 237 screened women, 62 placentae were selected for analysis, comprising 31 Salmonella-exposed cases (IgG/IgM-positive in placental and cord blood) and 31 gestational age-matched controls (IgG/IgM-negative). Placental tissues were processed for histology and stereology. Neonatal birthweights were also compared. Results: Stereological assessment revealed significantly higher mean volume densities of syncytial knots in the study group (0.4755 ± 0.04) compared to the controls (0.3342 ± 0.04, p = 0.0219). Syncytial denudation was increased in the study group (0.8113 ± 0.09) relative to the controls (0.1975 ± 0.08, p < 0.0001). Foetal capillary volume density was also significantly elevated in the study group (5.1010 ± 0.32) compared to the controls (3.562 ± 0.47, p < 0.0001). In contrast, intervillous space volume was significantly reduced in the study group (9.5810 ± 0.05) compared to the controls (11.593 ± 0.26, p = 0.0053). Neonates of exposed mothers showed a non-significant reduction in birthweight. Conclusion: Salmonella Typhi exposure in pregnancy induces subtle, yet significant alterations in placental architecture, compromising villous integrity and vascular organisation. Although birthweight may appear unaffected, the observed changes point to reduced placental efficiency and merit further research into their developmental consequences and long-term effects on babies. Full article

The use of unmanned aerial vehicle (UAV) pesticide spraying technology in precision agriculture is becoming increasingly important. However, traditional spraying methods struggle to address the precision application need caused by the canopy differences of fruit trees in orchards. This study proposes a UAV orchard variable-rate spraying method based on canopy volume. A DJI M300 drone equipped with LiDAR was used to capture high-precision 3D point cloud data of tree canopies. An improved progressive TIN densification (IPTD) filtering algorithm and a region-growing algorithm were applied to segment the point cloud of fruit trees, construct a canopy volume-based classification model, and generate a differentiated prescription map for spraying. A distributed multi-point spraying strategy was employed to optimize droplet deposition performance. Field experiments were conducted in a citrus (Citrus reticulata Blanco) orchard (73 trees) and a litchi (Litchi chinensis Sonn.) orchard (82 trees). Data analysis showed that variable-rate treatment in the litchi area achieved a maximum canopy coverage of 14.47% for large canopies, reducing ground deposition by 90.4% compared to the continuous spraying treatment; variable-rate treatment in the citrus area reached a maximum coverage of 9.68%, with ground deposition reduced by approximately 64.1% compared to the continuous spraying treatment. By matching spray volume to canopy demand, variable-rate spraying significantly improved droplet deposition targeting, validating the feasibility of the proposed method in reducing pesticide waste and environmental pollution and providing a scalable technical path for precision plant protection in orchards. Full article

This study addresses the parallel operation of multiple compressor units in the gas injection process of gas storage facilities. A multi-objective optimization model based on the NSGA-II algorithm is proposed to maximize gas injection volume while minimizing energy consumption. Thermodynamic models of compressors and flow–heat transfer models of air coolers are established. The influence of key factors, including inlet and outlet pressures, temperatures, and natural gas composition, on compressor performance is analyzed using the control variable method. The results indicate that the first-stage inlet pressure has the most significant impact on gas throughput, and higher compression ratios lead to increased specific energy consumption. The NSGA-II algorithm is applied to optimize compressor start–stop strategies and air cooler speed matching under high, medium, and low compression ratio conditions. This study reveals that reducing the compression ratio significantly enhances the energy-saving potential. Under the investigated conditions, adjusting air cooler speed can achieve approximately 2% energy savings at high compression ratios, whereas at low compression ratios, the energy-saving potential reaches up to 8%. This research provides theoretical guidance and technical support for the efficient operation of gas storage compressor units. Full article

Botulinum neurotoxin type A (BoNT-A) is widely used to reduce spasticity in children with cerebral palsy. Despite its therapeutic benefits, incomplete muscle recovery has been observed post-treatment. This study evaluated longitudinal BoNT-A effects on muscle morphology over one year in children with CP (n = 26, mean age: 5.19 years ± 3.26). Three-dimensional freehand ultrasound assessed medial gastrocnemius muscle volume (MV), muscle belly length (ML), cross-sectional area (CSA), and echo intensity (EI) at baseline and at 3, 6, and 12 months post-BoNT-A. Z-score normalization accounted for natural muscle growth. Linear mixed models analyzed muscular changes over time, and repeated-measures ANOVA compared muscle parameters to an age- and severity-matched control group (n = 26, mean age: 4.98 ± 2.15) at one-year follow-up. MV exhibited a declining trend at 3 (p = 0.005), 6 (p = 0.003), and 12 months (p = 0.007), while ML remained unchanged throughout follow-up (p = 0.95). The initially reduced CSA at 6 months (p = 0.0005) recovered at one year, and EI increased only at 3 months post-BoNT-A (p < 0.0001). At one-year follow-up, there was a trend for reduced growth rate (MV/month) (p = 0.035) in the intervention group, whereas the control group exhibited an increased muscle growth (p = 0.029). These findings suggest distinct recovery timelines for CSA and ML, which may explain the incomplete MV recovery and highlight substantial interindividual variation in recovery processes. Full article

This work introduces a wine glass-shaped planar ultra-wideband (UWB) antenna. The antenna achieves a compact form factor by reducing lateral width through Bézier curve shaping and a trident feed, while maintaining length for low-frequency operation. The wine-glass-shaped radiator increases shunt capacitance and enhances midband impedance matching, as demonstrated by equivalent circuit analysis, while the trident feed improves matching at higher frequencies. This design yields a 92% fractional bandwidth (3.2–8.7 GHz) within a compact volume of $0.37{\lambda }_0\times 0.13{\lambda }_0\times 0.0013{\lambda }_0$. The prototype is fabricated on two 50-μm-thick polyimide flexible copper-clad laminates (FCCL), and its performance is evaluated in an anechoic chamber. The measured results demonstrate omnidirectional radiation with an efficiency of over 80% across the UWB band. With broad operational range and compactness, the antenna is well-suited for IoT and wearable sensing applications. Full article

Over the past 20 years, the use of the global positioning system (GPS) in football has become widespread. This technology has facilitated the tracking of external load both during training sessions and matches. Creating an external load profile for each playing position within specific formations can assist the coaching staff in shaping the training load of the microcycle according to the demands of each position. The purpose of this study was to create the running performance profile for high-level young football players based on their playing position in the 1-4-2-3-1 formation and to investigate potential differences between positions. Additionally, the study aimed to compare the players’ running performance across the two halves of the match. The study involved 22 Under-19 players from the academy of a professional football team. Only matches where the team used the 1-4-2-3-1 formation were analyzed (10 matches). The playing positions were categorized as: Central Defensive Fielders (CDFs), Central Midfielders (CMFs), Forwards (FWDs), Wide Defensive Fielders (WDFs), and Wide Midfielders (WMFs). Player movement was tracked using GPS devices and categorized into four velocity zones: (Zone 1: 3.6–10.8 km/h, Zone 2: 10.9–18.0 km/h, Zone 3: 18.1–25.2 km/h, Zone 4: >25.2 km/h). Depending on whether normality was present in our data, either a one-way analysis of variance (ANOVA) or a Kruskal–Wallis test was conducted. A subsequent analysis was performed to compare the performance between the first and second halves of the match, using either the independent samples t-test or the Mann–Whitney U test. The results showed that CMF players covered the greatest total distance and had the highest movement velocity (distance/min) compared to all other positions (p = 0.001). In high-speed running (>18 km/h), CMF again covered the greatest distance, followed by WDF. In sprinting, CDF covered the shortest distance and reached the lowest maximum speed (p = 0.001). CMF performed the most accelerations and decelerations across all positions (p = 0.001). As for the entire team, total distance, movement rate, and the number of accelerations and decelerations decreased in the second half. All players except the WDF also showed a decrease in total distance, while midfielders experienced a notable drop in sprint distance. In conclusion, this study underscores the positional specificity of physical demands in elite football and the systematic decline in physical output as matches progress. While all positions demonstrated some level of second-half performance deterioration, midfielders experienced the most significant decreases in both volume and intensity-related metrics. These insights offer valuable implications for position-specific physical condition, recovery planning, and substitution strategies, helping to optimize performance and manage player load in elite football environments. It should be reiterated that the results of the present study apply exclusively to the 1-4-2-3-1 formation. Full article

The Sichuan Basin is a key area for shale gas energy exploration in China. However, the pore evolution mechanism and accumulation effect of the Lower Jurassic continental shale gas in the northeastern Sichuan Basin remain poorly understood. In this study, the pore structure characteristics of shale reservoirs and the dynamic accumulation and evolution of shale gas in the northern Fuling and Yuanba areas were systematically analyzed by adsorption experiments, high-pressure mercury injection joint measurement, and thermal simulation experiments. The results indicate the following: (1) The continental shale in the study area is predominantly composed of mesopores (10–50 nm), which account for approximately 55.21% of the total pore volume, followed by macropores (5–50 μm) contributing around 35.15%. Micropores exhibit the lowest proportion, typically less than 10%. Soluble minerals such as clay minerals and calcite significantly promote pore development, while soluble organic matter may block small pores during hydrocarbon generation, which facilitates the enrichment of free gas. (2) The thermal simulation experiment reveals that pore evolution can be divided into two distinct stages. Prior to 450 °C, hydrocarbon generation leads to a reduction in pore volume due to the compaction and transformation of organic matter. After 450 °C, organic matter undergoes cracking processes accompanied by the formation of shrinkage fractures, resulting in the development of new macropores and a significant increase in pore volume. This indicates that thermal energy input during the thermal evolution stage plays a key role in reservoir reconstruction. (3) The early Jurassic sedimentary environment controls the enrichment of organic matter, and the Cretaceous is the key period of hydrocarbon accumulation. Hydrocarbon generation and diagenesis synergistically promote the formation of gas reservoirs. The Cenozoic tectonic activity adjusted the distribution of gas reservoirs, and finally formed the enrichment model with the core of source–reservoir–preservation dynamic matching. For the first time, combined with dynamic thermal simulation experiments, this study clarifies the stage characteristics of pore evolution of continental shale and identifies the main controlling factors of shale gas accumulation in the Lower Jurassic in northeastern Sichuan, which provides a theoretical basis for continental shale gas exploration and energy resource development, offering important guidance for optimizing the selection of exploration target areas. Full article