Comprehensive characteristics of a seawater hydraulic pilot-operated pressure-reducing valve with constant pressure output were analyzed. A rated pressure of 15MPa and a rated flowrate of 40L/min were offered in the numerical work. Static and dynamic analyses show good behaviors: The settling time is less than 0.2s, the output pressure variation is about 0.3MPa at the maximum when input pressure or flowrate is flucturing, and the steady external leakage is below 0.025L/min. The pilot spring regulates the output pressure and the main spring has an ability to adjust the output pressure variation faintly. The narrow hole diameter of the adjustable damping plugs is negatively related to the respond time. And appropriately raising the spring chamber volume can evidently reduce outlet pressure impact of the valve when input mutations happen.

Hydraulic systems are widely used in industrial applications, but the problem of heating has become an important reason to restrict the promotion of hydraulic technology. The high temperature, will seriously affect the operation of the hydraulic system, even cause stuck and other serious failure. Based on the analysis of the heat damage of the hydraulic system, this paper gives the reasons for this problem, and it is showed by the application that the energy analysis can accurately locate the main reasons for the heating of the hydraulic system, which can give strong practical guidance.

Due to the many parts of the twin-screw pump, each part has multiple parameters. These parameters usually show mixed technical states, making it difficult to select the parts with excellent parameters to assemble the pump. Based on analyzing the factors affecting the vibration state of the twin-screw pump, this paper establishes its two-level fuzzy comprehensive evaluation mathematical model. By creating membership functions and combining them with the measured data, the technical state of each parameter is quantified to realize the pre-assessment of the vibration technical state of the twin-screw pump. The example shows that the application of the two-level fuzzy comprehensive evaluation method in this field is feasible.

Road sign detection is crucial for highway maintenance but often suffers from sign loss, occlusion, and spatial misjudgments such as repeated local detections or mapping errors. To address these issues, this study proposes YOLO-DeepSort, a tracking and detection framework integrating a novel Spatial Multivariate Clustering Algorithm with GPS information (SCMCg). The YOLOv9 detector is augmented using Mixed Local Channel Attention (MLCA) and DualConv modules to enhance image feature extraction and contextual awareness while compressing the theoretical model volume. In the tracking phase, DeepSort combined with SCMCg employs Delaunay triangulation and hierarchical GPS constraints to refine spatial clustering and data association. Validation was conducted on a mixed dataset comprising the CCTSDB and self-collected images from a Ningxia national road. Experimental results indicate that the proposed model operates efficiently at 21.4 M parameters, achieving a precision of 97.8%, a mean Average Precision (mAP) of 91.2%, and a tracking Success Rate of 97.3%. Compared to the baseline YOLOv8-DeepSort, absolute improvements of 4.60% in precision and 4.20% in mAP were observed. The integrated framework effectively mitigates occlusion and tracking spatial errors, providing a robust and lightweight methodology for the automated condition assessment of intelligent transportation infrastructure.

In order to optimize the comprehensive characteristics of a water hydraulic pilot-operated pressure-reducing valve, numerical orthogonal experimental design was adopted. Six parameters of the valve, containing diameters of damping plugs, volume of spring chamber, half cone angle of main spool, half cone angle of pilot spool, mass of main spool and diameter of main spool, were selected as the orthogonal factors, and each factor has five different levels. An index of flowrate stability, pressure stability and pressure overstrike stability (iFPOS) was used to judge the merit of each orthogonal attempt. Embedded orthogonal process turned up and a final optimal combination of these parameters was obtained after totally 50 numerical orthogonal experiments. iFPOS could be low to a fairly low value which meant that the valve could have much better stabilities. During the optimization, it was also found the diameters of damping plugs and main spool played important roles in stability characteristics of the valve.