In recent years, rapid development has been continuously observed in China’s manufacturing industry, where AGVs automated guided vehicles have been increasingly adopted by enterprises as core equipment in intelligent logistics systems. To ensure the efficiency of warehouse operations, addressing the issue of transportation path conflicts among AGVs has garnered growing attention from researchers. A literature review on the issue of multi-AGV path conflicts in warehouses was conducted from two perspectives. First, from the perspective of conflict types, the research problems were categorized into collision problems and deadlock problems, and the current state of research on multi-AGV collision avoidance strategies under different conflict types was analyzed. Second, from the perspective of model-solving algorithms, the study divides the approaches into heuristic algorithms and reinforcement learning algorithms, analyzing their application in multi-AGV path conflict issues in warehouses in recent years. Finally, the existing literature was summarized, and future directions for addressing multi-AGV path conflicts in warehouses were proposed.

Crack detection is crucial to maintaining the structural safety of buildings. In recent years, convolutional neural networks based on deep learning have provided new solutions for crack detection. However, this comes at the cost of huge computing resources, so there are problems of poor real-time performance and low detection efficiency in practical applications. To address this problem, a lightweight MSFC (multi-scale dynamic fusion convolution module) based on the U-Net architecture was proposed to improve the efficiency of crack segmentation. To verify the effectiveness of the proposed method, a dataset Crack2045 containing 2 045 crack images was constructed and experiments were conducted on this dataset. The experimental results show that compared with the original U-Net model, the model using the MSFC module reduces 78.51% of the parameters and 63.75% of the computational complexity while maintaining the same accuracy. At the same time, the MSFC module has a certain degree of generalization and can be seamlessly integrated into different semantic segmentation models. This study not only provides an efficient deep learning method for crack detection, but also provides new possibilities for model deployment in resource-constrained environments.

In order to investigate the water-holding mechanism and infiltration law of modified glutinous rice-based reconstructed soil layer under rainfall, soil column infiltration tests were firstly conducted to analyze the influence of modified glutinous rice-based material dosage variations on macroscopic vertical infiltration patterns of reconstructed soil. NMR (nuclear magnetic resonance) and scanning electron microscopy technologies were employed to investigate microporous structure and water-holding characteristics under different material dosages. Based on the findings, reconstructed soil with optimal material dosage (12.5%) was selected for rainfall slope modeling tests, through which moisture transport patterns and post-precipitation water redistribution characteristics in reconstructed soil layers were investigated.The results show as follows. With the increase of the dosage of modified glutinous rice-based materials, the number of effective pores (mesopores) increases and then decreases, the number of small pores gradually increases and the number of large pores gradually decreases, and the soil water-holding capacity is optimal when the dosage is 12.5%. increases and the number of large pores gradually decreases, and the soil water-holding capacity is optimal when the dosage is 12.5%. Modified glutinous rice-based materials wrap around, adsorb to soil particles, and combine with gravel to form agglomerates, thereby changing the pore structure of the soil, enhancing the soil water retention capacity, and improving the effectiveness of soil water. Under the condition of 25 mm/h rainfall intensity, an increase in slope gradient led to the decrease of infiltration depth of each cross-section, and the infiltration site shifted significantly (from the top to the foot of the slope). The depth of slope infiltration during the entire rainfall period decreased significantly with the increase of slope gradient, and water in the slope was redistributed at the end of rainfall. The average infiltration depth of the slope at 35°, 55°, and 75° was 10 cm, 8 cm, and 5 cm, respectively. This study is significant for improving the technical system of ecological slope restoration and guiding conservation and management efforts.

When tunnels with extra-large cross-sections pass through layered rock formations, given the unique structural characteristics of these layers, suitable control strategies must be implemented to mitigate any adverse impacts. Based on the extra-large section tunnel project of Chongqing Guobo Center Station passing through layered rock, numerical simulations, and field monitoring are adopted in this study to compare the mechanical differences between balanced and unbalanced anchor cable supports during tunneling. The results show that compared with the balanced anchor cable support, the influence of the unbalanced anchor cable support on the control difference of displacement and plastic zone of surrounding rock is not significant. However, the unbalanced anchor cable supportcould significantly affect the bending moment distribution range of the vault of lining structure, while having little influence on the peak bending moment and the distribution and magnitude of axial force, with the differences between them being 8% and 11.2% respectively. The reduction in the safety redundancy of the lining structure under the unbalanced anchor cable support is less, and the stability of the tunnel in layered rock could still be maintained. From the perspectives of economy and construction convenience, the amount of anchor cable could be saved by 51%, and the economic advantages are more prominent, which is more advantageous in the construction of tunnels with large sections in layered rock. The effectiveness of the unbalanced support in maintaining tunnel stability is confirmed by field monitoring. The discrepancy between the numerical simulation and field monitoring results is merely 2 mm, demonstrating high consistency and validating the accuracy of the calculations. Critical insights for the design and construction of future similar tunnels in layered rock are provided.

The perforated walls of transonic wind tunnels with different parameters have a considerable influence on the flow field quality of the test section, therefore, the characterization of the perforated wall parameters is extremely essential for the design of the test section of transonic wind tunnels. The relationship between the characteristic parameters near the perforated wall of three-dimensional and two-dimensional perforated wall models was studied using the single straight perforated hole of the FL-3 wind tunnel. The mass and velocity distributions of the two-dimensional and three-dimensional perforated wall show obvious linear characteristics under different pressure difference coefficients. It is proposed that the two-dimensional perforated wall can be equivalent to the flow characteristic parameters of the three-dimensional perforated wall by the corresponding coefficient transformation under the same incoming flow Mach number when the wall pressure difference coefficient and the boundary layer displacement thickness are satisfied. A two-dimensional calculation model of the transonic wind tunnel was established, and the effects of perforated wall parameters and free stream Mach number on the flow field and flow characteristic parameters near the wall in the test section were analyzed by numerical method. When l / d = 1, the increase in perforated wall size makes the wall pressure difference coefficient increase, otherwise, the relative area of flow in the perforated wall decreases. As d = 2 mm, the flow field was proposed. When l / d > 2, ΔC_p tends to be stable. When l / d = 3, m' and S / d are the maximum values, in the Ma = 0.8 ~ 0.9 range, m' is positively correlated with the incoming Mach number, but ΔC_p changes little. The pressure difference coefficient and velocity component obtained under different perforated wall parameters have certain guiding significance for understanding the perforated wall flow and adjusting the perforated wall of the test section.

The transportation via high-pressure long-tube trailers serves as a crucial method for medium-short distance transfer of flammable and explosive gases such as hydrogen and natural gas. As the core equipment in this system, the trailer filling compressor operates under continuously varying discharge pressures across wide ranges during gas loading processes. Current research and development phases face challenges in fully replicating real-world operating conditions for thermal performance testing. Addressing this requirement, this study proposes a closed-loop experimental system with gas staged recovery and continuous release functions, featuring continuous backpressure regulation capability for trailer filling compressors. The system enables the simulation of actual filling processes by creating both stable and dynamic operating conditions with wide-ranging discharge pressure variations for comprehensive compressor testing. A mathematical model of the testing system was established using zero-dimensional simulation methodology. Systematic investigations were conducted on parameter variations and operational characteristics throughout complete testing procedures, including initial pressurization, compressor startup/shutdown, and wide-range operational testing. Through optimized improvements in system configuration and component matching, critical operational constraints were achieved: gas reservoir temperatures were maintained below 85 °C during testing, and post-recovery system pressures were reduced below 1.5 MPa. These optimizations resulted in the development of a refined and rational testing system and methodology for trailer filling compressors, effectively addressing the technical challenges in simulating actual working conditions during compressor development phases.

The response of an aircraft engine to bird strikes has the fan blade as its primary component, and the flight safety of the aircraft is directly impacted by the dynamic damage caused by stress changes. A three-dimensional model of a near-real bird body was established in this paper based on the structural features of the “bar-headed goose”. The dynamic damage of the blade was studied in consideration of the take-off-climb and approach-landing stages where bird strike accidents are most likely to occur for aircraft, with the effects of different impact speeds, fan blade speeds, and bird impact attitudes being taken into account. It is indicated by the results that the axial damage and deformation of fan blades tend to be increased monotonically with the increasing of aero-engine speed and relative velocity of bird strike blades. Additionally, as the fan blade speed is increased, the stress peak value after a bird strike shows a V-shaped trend, with the smallest stress peak value being occurred at 2 005 r/min. Furthermore, as the contact area between the bird body and fan blade at the initial collision moment is increased, both the stress and damage degree of the blade are gradually increased across different postures. When impacted at a 90° posture, the axial damage deformation of the blade is reached to 60.887 mm. Valuable reference for anti-bird strike design considerations for aero-engine fan blades is provided by these research findings.

The cornering stiffness of automobile tires is closely linked to the vehicle’s handling characteristics, and accurately estimating the tire cornering stiffness in real time is of significant importance for enhancing the stability of vehicle handling. Addressing the challenge of direct measurement of cornering stiffness, a real-time identification method based on the estimation of tire lateral force and slip angle was proposed. Firstly, considering the influence of longitudinal force on lateral force, a tire lateral force estimator was designed based on the yaw dynamics model and sliding mode observer algorithm, followed by the design of a slip angle feedback estimator based on the estimation error of lateral force. Secondly, a nonlinear tire force model that describes the relationship among tire lateral force, slip angle, and cornering stiffness was established. Taking the real-time estimated lateral force and slip angle as inputs, a recursive least squares online identification algorithm with limited memory was designed to address the issue of estimation error due to “data saturation” and improve identification accuracy. Finally, joint simulation experiments using Simulink and CarSim were conducted. The experimental results indicate that the estimation error of tire lateral force is approximately 4.153 9% on average, while the estimation error of tire slip angle is 3.285 2% on average. The identification model based on the recursive least squares method is robust to changes in road conditions, demonstrating good tracking accuracy and stability under both high and low adhesion conditions, with an average estimation accuracy of tire cornering stiffness of approximately 98.379 3%.

In order to solve the contradiction between ecological maintenance and agricultural production water demand, the minimum water demand for ecological restoration in arid areas was determined. The lower reaches of the Tarim River were selected as the typical study area. Suitable areas for vegetation growth were determined through the PNV (potential natural vegetation) simulation method, while the suitable growth ranges and distribution areas of trees, shrubs, and grasslands were analyzed. The minimum ecological water demand for the lower reaches of the Tarim River was calculated by the multi-year evapotranspiration data from the AET dataset. The results show as follows. The PNV results obtaine in the lower reaches of the Tarim River are dominated by shrubs, forests and grasslands are highly dependent on water resources, mainly distributed around river channels. The forest and grassland in the study area show high growth potential, while the shrub distribution areas far from the river show a degradation trend. According to PNV simulation results, the ecological water demand in the lower reaches of Tarim River is about 11 279.23×10⁴ m³, of which shrubs account for the largest proportion, while woodland and grassland account for 7.4% and 5.36% respectively due to their small areas. The research results provide a new method for ecological restoration and determination of water transport capacity in arid areas, which can clarify the scope of ecological restoration and vegetation types in the basin, and contribute to the management and optimal allocation of regional water resources.

To analyze the crack development characteristics of different reinforcement concrete beams during bending failure, and to explore the acoustic emission characteristics and bending performance degradation of the beams, a four-point bending test was conducted in combination with acoustic emission technology to establish the relationship between the bending failure process and acoustic emission signals of three different concrete beams. The experimental results show that the RA(rise time/maximum amplitude)-AF(average frequency) signals during the damage evolution of concrete beams with different reinforcements have obvious differences, the proportion of shear crack signal RA of reinforced beams, less-reinforced beams, and super-reinforced beams is much higher than the proportion of diagonal crack signal AF. The common characteristics of the amplitude distribution of bending damage at various stages of differently reinforced beams are mainly reflected in the amplitude peaks in the frequency bands 4~6 kHz, 13.5~16 kHz, and 53~57 kHz. When the beam reaches a certain load, the amplitude peaks in the high-frequency band will suddenly rise, indicating the yielding of the internal reinforcement of the beam and the entry of the structure into the failure stage. This can be used as an important basis for monitoring the extent of internal damage to the structure through time-frequency transformation of acoustic emission signals.