Search Results (7,610)

This study addresses the problem of robust video-based tracking of laboratory rats in open-field and Y-maze experiments under challenging acquisition conditions, including non-uniform illumination, low contrast, and heterogeneous recording setups. Existing approaches based on classical image processing or deep learning often fail to maintain stable localization under such conditions or require large, annotated datasets. We propose a hybrid tracking framework that combines an improved motion–appearance voting mechanism with consistency-constrained optimization for open-field experiments, together with a comparative deep learning-based detection strategy for Y-maze analysis. The proposed method introduces (i) adaptive dual-threshold motion extraction, (ii) directionally constrained temporal validation, and (iii) a robustness-driven fusion of motion and appearance cues. Experimental results demonstrate that the proposed approach achieves reliable tracking with a maximum localization error below 10 pixels under severe illumination variations. In the Y-maze scenario, a comparative evaluation of multiple detectors (YOLOv5, YOLOv9, YOLO12, Faster R-CNN) highlights the trade-off between accuracy and inference time, with YOLOv9 providing the best balance. The main contribution consists of enabling robust behavioral quantification in low-quality experimental conditions using limited training data, bridging the gap between classical tracking robustness and deep learning flexibility. Full article

Photovoltaic (PV) power generation is inherently intermittent due to unpredictable irradiance variations, posing significant challenges for grid integration. While conventional power smoothing strategies mitigate short-term fluctuations, they do not explicitly enforce the tracking of a scheduled power trajectory. This paper proposes a dispatchable PV framework that integrates a hybrid convolutional neural network-long short-term memory (CNN-LSTM) model for precise day-ahead power forecasting with a real-time supercapacitor (SC) compensation strategy. The CNN-LSTM network captures complex spatiotemporal meteorological dependencies to generate a robust day-ahead reference trajectory. Concurrently, a supercapacitor energy storage system (SC-ESS) integrated at the DC-link level via a bidirectional buck–boost converter actively balances the instantaneous mismatch between this forecast trajectory and the actual PV generation. Unlike filter-based hybrid methods, the SC-ESS is employed as a direct forecast error actuator in a closed-loop control scheme. This strategy strictly enforces real-time forecast tracking while preserving maximum power point tracking (MPPT) and DC-link voltage stability. Simulations and laboratory experiments under rapidly varying irradiance confirm that the proposed method significantly reduces power deviations from the forecast reference and improves short-term power predictability without imposing excessive stress on the SC. This forecast-aware strategy effectively enhances the dispatchability of PV systems, providing a practical solution for grid-supportive operation. Full article

Courses in electromagnetism and related technical subjects are often dominated by lecture-heavy instruction and complex mathematical concepts, which can make it difficult for students to stay engaged. This is particularly problematic in today’s hyper-digitalized society, where constant screen exposure and shortened attention spans challenge traditional learning methods. While computer-based tools and hands-on laboratories offer some pedagogical improvements, they often fall short in terms of interactivity, dynamism, adaptiveness, and student engagement. In an effort to enrich the learning experience and boost student motivation, we have created a gamified learning activity for the undergraduate course “Radiocommunications”—commonly referred to as Antennas and Propagation in other institutions— implemented in the form of a question-based board game. The activity, carried out over three academic years, is fully aligned with the course syllabus and encourages active learning, healthy competition, and collaborative problem-solving. Custom-made materials—including a game board, 270 question cards, wildcards, and incentive-based rewards—were developed specifically for this purpose. The qualitative results from a student survey, together with statistical evidence from hypothesis testing, suggest that the activity enhances conceptual understanding, helps students connect ideas across related subjects, and contributes to a more motivating and enjoyable learning experience. Full article

Diseases caused by Fusarium spp. vary around the world. It is important to determine the causals agents and indigenous antagonists against these pathogens. Thus, this study aimed to (i) determine the pathogens of root rot and yellow leaf disease (RRYLD), (ii) select Trichoderma spp. strains to control the pathogens, and (iii) evaluate methods for preparing the antagonistic fungi. Diseased soil samples were collected from pomelo orchards in Ben Tre province, Vietnam. The experiment isolated 08 Fusarium spp. strains, with the fastest growth in PDA in FP-C16, FP-B18, FP-B16, and FP-B03 (8.33–17.3 mm) on day 4 of culture. They were identified as Fusarium fujikuroi FP-C16, F. verticillioides FP-B18, F. verticillioides FP-B16, and F. incarnatum FP-B03. On the other hand, 25 Trichoderma spp. strains were isolated from the pomelo rhizosphere. Among them, 13 Trichoderma spp. strains showed rapid growth and strong antagonistic activity against two Fusarium spp. strains under laboratory conditions. The two Trichoderma spp. strains TP-C40 and TP-G50 had antagonistic efficiencies against FP-C16 and FP-B16 at 47.7–63.5%. The two selected Trichoderma spp. strains were identified as Trichoderma asperellum TP-C40 and T. yunnanense TP-G50. The two Trichoderma spp. strains TP-C40 and TP-G50 reduced the number of leaves and roots infected by Fusarium spp. Full article

The Gulong shale oil reservoir is characterized by high clay content and strong heterogeneity, with substantial variations in mineral composition among different intervals. However, existing fracability evaluation methods for such continental shales remain inconsistent and often rely on oversimplified two-dimensional fracture descriptors, lacking a multi-parameter quantitative framework derived from three-dimensional fracture characterization. In this study, the Q1 and Q9 members of the Gulong shale oil were selected, and laboratory-scale hydraulic fracturing simulation experiments were conducted using supercritical carbon dioxide (SC-CO₂), liquid CO₂, and water as the fracturing media. Within a fractal-theory framework based on CT-derived three-dimensional reconstructions, a multi-scale evaluation index system was established by integrating fractal dimension, fracture density, and spatial connectivity. The experimental results demonstrate that fluid properties exert a decisive influence on rock failure behavior. Owing to its ultra-low viscosity and strong diffusivity, SC-CO₂ can significantly reduce formation breakdown pressure while effectively activating natural weak planes to generate a more complex fracture network. For the Q9 shale, the breakdown pressure under SC-CO₂ is reduced by 11.91% and 8.33% relative to water and liquid CO₂, respectively. Moreover, the fracture fractal dimension reaches 2.41 under SC-CO₂, which is markedly higher than the values obtained under liquid CO₂ (2.18) and water (2.12). Mineral composition and densely developed bedding are the key factors inducing fracture branching and deflection, whereas injection rate and an asymmetric stress field regulate the internal energy-release rate and stress path, thereby influencing fracture crossing capability and aperture evolution. Based on the experimental dataset, a fracture complexity index (FCI) evaluation model was developed: under SC-CO₂ fracturing, the FCI values are 8.92 for the Q9 member and 4.43 for the Q1 member, and the model predictions are in good agreement with physical observations. This work elucidates the failure mechanism of the Gulong shale under multi-field coupling and provides a theoretical basis for optimizing hydraulic fracturing and evaluating fracability in unconventional reservoirs through the proposed FCI-based assessment framework. Full article

To solve the problems of high injection pressure and low water injection in an ultra-low-permeability reservoir, nanoemulsion was injected to reduce the surface interfacial tension, change the wettability, and achieve the purpose of depressurization. In this paper, the surface and interfacial tension, wettability properties, and particle size distribution characterization of nanoemulsion were determined, and the performance of nanoemulsion was evaluated by laboratory experiments such as core displacement. At the same time, the depressurize and augmented injection mechanism of the nanoemulsion was studied through a scanning electron microscope. The experiment shows that the nanoemulsion system has good compatibility with brine. With the increase in temperature, the surface and interfacial tension does not change, and there is no precipitation. And the system can reduce the oil–water interfacial tension to about 1 mN·m⁻¹ under the best conditions. By measuring the wettability angle of nanoemulsion at the concentration of 0.1% to 0.5%, which can adjust the wettability of the rock surface, the hydrophilicity is weakened. The depressurization performance of nanoemulsion under different injection rates, concentrations, and slug sizes was also compared through core displacement experiments, to provide reasonable experimental support for field operations. In the most reasonable case, the depressurization rate after using nanoemulsion can reach 16.78%. Full article

The complex propagation behavior of hydraulic fractures (HFs) in strongly heterogeneous conglomerate reservoirs poses significant challenges for effective reservoir stimulation. In particular, the interaction between fractures and gravel-induced heterogeneity often leads to highly tortuous fracture networks and uneven stimulation efficiency. To address this issue, a series of laboratory true triaxial hydraulic fracturing experiments were conducted on artificially prepared conglomerate specimens with controlled gravel size and distribution. A quantitative evaluation index, termed the Fracture Complexity Index (FCI), was proposed to characterize the tortuosity and complexity of fracture networks by integrating multiple geological and engineering factors. The effects of cluster spacing and fracturing fluid viscosity on multi-fracture propagation behavior were systematically investigated. The results show that increasing cluster spacing enhances inter-fracture interaction and promotes fracture tortuosity, while lower fluid viscosity facilitates fracture branching but may limit effective propagation distance due to energy dissipation. To further quantify the trade-off between fracture complexity and propagation extent, a dimensionless fracture length was introduced and combined with FCI to establish a fracture morphology evaluation framework. This framework enables the classification of fracture patterns and reveals the coupling relationship between engineering parameters and fracture geometry. The findings provide new insights into the mechanisms of fracture propagation in conglomerate reservoirs and offer a quantitative basis for optimizing fracturing design, particularly in balancing fracture complexity and effective stimulation range in strongly heterogeneous formations. Full article

Addressing the problem of limited methane (CH₄) recovery degree under different production conditions in a target low-permeability carbonate gas reservoir, this study intends to further investigate the effect of carbon dioxide (CO₂) injection on enhanced gas recovery (EGR). A group of long-core physical simulation experiments of CO₂ injection for EGR was adopted. Field injection–production parameters were converted to laboratory conditions through similarity criteria to simulate the actual production process of gas wells. Systematic experiments on CH₄ depletion and CO₂ displacement were carried out under different irreducible water saturation, gas injection timing pressure and injection rates. The influence laws of each key parameter on the CO₂ breakthrough time and CH₄ recovery degree were analyzed emphatically, and the optimal injection–production scheme was obtained. For the target low-permeability carbonate gas reservoir (permeability < 1 mD), the optimal CO₂ injection scheme is as follows: for layers with medium to high irreducible water saturation (≥40%), CO₂ injection at a rate of 36,000 m³/d per well after the end of stable production (formation pressure > 7.38 MPa) can increase the CH₄ recovery degree by 3–5%. This study provides experimental support for the optimization of CO₂ injection schemes for enhanced recovery in gas reservoirs and the adjustment of gas reservoir development strategies under different irreducible water saturation conditions. Full article

To explore robotic peach picking in different modes, this study examined the effects of various peach picking modes on harvesting force and time. A finite element model of peach harvesting structure was established, and harvesting experiment parameters were based on the Box–Behnken design. Harvesting was simulated to collect response time and force data. Subsequently, the optimal harvesting rate under different picking modes was determined. Different picking modes were tested by simulating identical fruit harvesting in the laboratory at the optimal harvesting speed to determine the peak harvesting force and duration. The Bend mode had the lowest picking pressure and the shortest average picking time at 0.7 MPa and 4.2 s, respectively. The Pull and Twist modes had similar pressures and picking times at 1.2 and 1.1 MPa and 5.2 and 5.6 s, respectively. Harvesting in the orchard allowed for harvesting force and duration measurement under different picking modes. The differences in picking pressure and time among the three picking modes increased compared with those of simulated picking, with specific patterns being observed. Picking pressure appeared at P1max, and differences in picking time were prevalent during separation. This study offers valuable insights for future improvements in harvesting modes and efficiency enhancement. Full article

Hainan is the dominant production area of the red-fleshed pitaya (Hylocereus undatus) cv. ‘Jindu No.1’ in China, and cutting propagation is the main method for its large-scale seedling cultivation. Plant growth regulators (PGRs) are the key factors regulating the rooting of cuttings. Existing studies mostly focus on the concentration optimization of a single agent, lack systematic broad-spectrum screening of commonly used PGRs in agriculture, and have the problem of disconnection between laboratory results and field production. To screen an efficient root-promoting PGR scheme suitable for large-scale seedling cultivation in Hainan production areas, this study established a three-level experimental system of “broad-spectrum primary screening→gradient re-screening→soil culture scenario verification”, used 14 kinds of PGRs commonly used in agricultural production as materials, and carried out a systematic evaluation combined with principal component analysis (PCA). 1-naphthaleneacetic acid (NAA), indole-3-acetic acid (IAA) and potassium indole-3-butyrate (K-IBA) were identified as high-efficiency agents in the primary screening, with a rooting rate of 100%, and the core root morphological indexes were significantly better than those of the water control (p < 0.05). Two independent experiments verified the stability of the “total growth–thickness” binary regulation mechanism of the pitaya root system. In the re-screening test, 400 mg·L⁻¹ NAA had the best comprehensive performance, synergistically improving the total root growth and root thickness, and 125 mg·L⁻¹ K-IBA had the most significant effect in promoting the longitudinal extension of roots, with the average root length increased by 760.0% compared with the control. Soil culture tests confirmed that the two optimal schemes had stable and reliable application effects in field substrate cultivation. The results of this study can provide technical support for the large-scale seedling cultivation of ‘Jindu No.1’ pitaya, and the established three-level screening system also provides a methodological reference for PGR screening in cutting propagation of similar tropical crops. Full article

During coalbed methane (CBM) production, coal reservoir pore/fracture structure varies dynamically under the action of fluid–solid coupling. And coal reservoir permeability changes accordingly. In order to factually investigate the dynamic changes in coal reservoir permeability in the CBM well drainage process, a comparative simulation experiment on the difference in coal permeability sensitivity to confining pressure (external pressure) and pore pressure (internal pressure) was carried out in this study. The results show that coal permeability presents a typical negative exponential decline with a decrease in pore pressure. The pore pressure sensitivity experiment can effectively simulate the permeability sensitivity characteristics caused by coal reservoir pressure. Based on the negative exponential function relationship between permeability and effective stress, a new calculating method for the effective stress coefficient was deduced. Namely, its value could be expressed as the quotient of the pore pressure sensitivity curve regression coefficient divided by the confining pressure sensitivity curve regression coefficient. A dynamic theoretical model for coal reservoir permeability characterized by reservoir pressure was systematically constructed based on the unique fluid (gas/liquid)–solid coupling characteristics of coal reservoirs. Furthermore, the general characteristics of the stress sensitivity of coal permeability during coalbed methane (CBM) recovery were analyzed. The dynamic evolution characteristics of coal reservoir permeability in the study area were further examined. Taking the production and drainage data of a typical actual CBM production well as an example, the theories regarding the permeability sensitivity of coal reservoirs to reservoir pressure presented in this paper were validated in practice. This indirectly confirmed the rationality and accuracy of the calculation method for the effective stress coefficient obtained through laboratory-based permeability sensitivity simulation experiments. This research provides robust theoretical support for the systematic monitoring and prediction of fluid production, reservoir pressure, and permeability during the CBM production process, carrying significant practical implications. Full article

Given that flood disasters often occur in areas without sufficient instrumentation, conventional observation networks alone may be inadequate to capture the actual evolution of flood events. However, video content from diverse sources such as smartphones, dashboard cameras, surveillance cameras, and helicopters or drones used for rescue, reconnaissance, or reporting, are increasingly collected incidentally and are gaining attention as complementary sensing modalities. Quasi-viewpoint fixation is key to quantitative hydraulic measurements because such videos involve significant changes in their point of view over the course of a given clip. To this end, we developed a quasistatic stabilization technique for social sensing referred to as QS4. The results of a laboratory experiment show that QS4 reproduced velocity distributions comparable to those of a fixed camera for pan-dominant videos recorded with a moving camera. In the 2024 Tsukada River flood, QS4 yielded stable velocity fields despite high turbidity, driftwood, and partial occlusions. Following the blockage of a bridge, flows were detoured along buildings shifting from a channel to flow through farmland, where ~5 m/s flows caused building failures that could not be detected by fixed observations. QS4 offers a practical pathway for transforming incidental videos into quantitative hydraulic observations. Full article

In petroleum drilling, conventional automatic drilling systems still rely heavily on manual intervention, which often leads to poor stability, limited multivariable coordination, and large fluctuations in drilling pressure. To address this problem, this study develops a hydraulic drawworks-based autodriller system with integrated power, drive, actuation, and control units, and establishes a mechanical-hydraulic-control co-simulation model for the coordinated regulation of drill-string hoisting speed and surface weight-on-bit (SWOB). Based on this platform, a dual-loop control framework is developed in which the inner loop uses linear active disturbance rejection control (LADRC) for rapid disturbance estimation and compensation, while the outer loop uses PID control for tracking regulation. Feedforward compensation is introduced to handle predictable load variation, and PSO-assisted fuzzy tuning is used to improve adaptability under varying operating conditions. Simulation results show that, compared with conventional cascaded PID control, the proposed controller reduces drawworks speed and SWOB overshoot by 12.5% and 40%, respectively, while the corresponding settling times are shortened by 1.805 s and 2.443 s. Prototype experiments on a scaled test platform further show that the proposed controller can be implemented on physical hardware and can maintain stable real-time regulation under laboratory conditions. These results support the feasibility of the proposed framework for coordinated hydraulic drawworks control under the simulated and laboratory-scale conditions considered in this study. Full article

In coaxial twin-rotor helicopters, the minimum blade tip distance may approach danger thresholds during rotor intersection under high-speed rotation and complex aerodynamic conditions, posing collision risks. This study proposes a multi-sensor fusion approach for measuring the blade collision warning parameter $d$, which maps the collision risk into a single evaluation metric and provides stable real-time outputs of phase, spatial position, and inter-blade distance under high-speed operational conditions. A collaborative measurement scheme integrating encoder-based phase detection, tip-tracking camera positioning, and millimeter-wave radar distance measurement was developed. A dynamic rotor motion simulation experimental platform with single-side rotation and rigid blades was constructed to validate the measurement performance under varying rotor speeds and blade tip distances. Experimental results indicate that measurement errors remain within ±1.87 mm, repeatability errors are below 0.67 mm, and the coefficient of variation is under 0.2%, confirming the accuracy and stability of the proposed method under dynamic conditions. Additional multi-speed experiments show that, over the tested rotational-speed range, the error of $d$ remains within (−5.86 mm, 6.57 mm), although the fluctuation of the results increases moderately at higher speeds as the blade intersection duration becomes shorter. The proposed approach provides a laboratory-validated technical basis for blade collision risk assessment and future warning implementation in coaxial twin-rotor helicopters. Full article

To solve the problems of easy fracture of reaming cutter arms and mechanical jamming leading to equipment damage when mechanical reaming equipment is used for anchor hole reaming in soft rock roadways, this study proposes the development of a high-efficiency reaming device with a simple structure. This study combines theoretical analysis, numerical simulation, and laboratory experiments to systematically investigate the key parameters of high-pressure water jet reaming equipment. The results show that under the same conditions, the maximum velocity of the high-pressure water jet decreases with an increase in the number of nozzles and the nozzle spacing. Although the correlation between the maximum jet velocity and nozzle angle is weak, the jet velocity acting on the anchor hole wall reaches its peak at a nozzle angle of 60°. Based on the simulation results, a 1:1 scale nozzle model was manufactured using 3D printing technology, and high-pressure water jet reaming experiments and bolt pull-out tests were carried out at a pressure of 20 MPa. The experimental results demonstrate that the optimal reaming effect is achieved with a nozzle configuration of 3 nozzles, 10 mm spacing, and a nozzle angle range of 45–60°. Specifically, after reaming with the nozzle at a 60° angle and 10 mm spacing, the bolt anchoring force reaches 51.99 kN, representing a 41.16% increase in anchoring strength compared with conventional anchoring. This research provides technical support for the engineering application of anchor hole reaming technology in soft rock roadways and is of great significance for improving the support effect of soft rock roadways. Full article