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NGO-MRE combined with DELM for bearing fault diagnosis
Get PDFTo improve the effectiveness of Multiscale Range Entropy (MRE) in extracting features from rolling bearing faults, this paper proposes a novel bearing fault diagnosis method that combines the Northern Goshawk Optimization (NGO) algorithm, MRE, and a Deep Extreme Learning Machine (DELM). First, the raw vibration signal is decomposed using Variational Mode Decomposition (VMD) to obtain its Intrinsic Mode Functions (IMFs). Second, the NGO algorithm is employed to optimize the MRE parameters, using the minimum crest factor as the objective function. Then, using these optimized parameters, MRE is applied to extract fault features. The resulting feature set undergoes dimensionality reduction to create the final sample set. Finally, an NGO-optimized DELM is used for fault classification. The experimental results demonstrate that this method effectively extracts the characteristic signals of rolling bearing faults through robust parameter optimization, thereby improving the accuracy of fault diagnosis
Investigating the mechanism of X80 pipeline failure under landslide impact
Get PDFAs energy demand continues to grow and environmental issues become more severe, the development and utilization of clean energy natural gas are becoming increasingly important. This paper focuses on the impact mechanism of landslide disasters on pipelines, analyzing how landslide displacement, width, pipeline wall thickness, and internal pressure affect pipeline stress and displacement. The study finds that landslides cause stress concentration at the middle and boundary positions of pipelines. As landslide displacement increases, pipeline stress also increases. For example, when landslide displacement is 1.2 meters, pipeline stress is approximately doubled compared to when the displacement is 0.6 meters. This research aims to explore the impact mechanism of landslide disasters on the stress response of natural gas X80 pipelines, with the goal of providing technical support for their stability and reliability
Experimental analysis of running wheel for a straddle monorail vehicle
Get PDFThis article conducts in-depth research on the force analysis of the test running wheel of a certain type of straddle monorail vehicle, based on the tire six-component force test and wheel dynamic stress test. The main research objective is to accurately identify the factors affecting the wheel strength, thereby providing a solid foundation for subsequent design optimization and safety enhancement. The research commences with a meticulous calibration of the vehicle connecting rod in the laboratory, aiming to acquire the “force-strain” coefficients under both tension and compression conditions. A novel approach lies in the verification of calibration accuracy through a detailed comparison with experimental results, ensuring the reliability of subsequent data acquisition. By strategically installing displacement sensors at various positions to measure the vehicle's dynamic displacement and detecting the strain of the connecting rod, the study innovatively calculates the six-component force data of the tire, which provides a comprehensive data basis for analyzing the forces acting on the wheel hub. Then evaluating the fatigue strength of the wheel hub under AW0 and AW3 operating conditions based on the IIW standard, the research uncovers unique findings. It is revealed that, although the maximum dynamic loads of the vertical force of the running wheel, the lateral force of the guide wheel, and the lateral force of the stabilizing wheel are within the limit load range with a certain safety margin, there are 1 point and 3 points on the wheel hub under AW0 and AW3 working conditions, respectively, that fail to meet the fatigue strength criterion requirements. The maximum equivalent force amplitude at Measurement Point 3 of the inner hub reaches 51.4 MPa, while the calculated service mileage is only 31,000 kilometers. This discovery is of great significance as it precisely pinpoints the weak points of the wheel hub, which is a major contribution to the field. Moreover, during the analysis of the wheel hub's dynamic stress during emergency braking and the influence of polygonal wear on it, the research confirms that there is no abnormal change in the wheel hub’s dynamic stress during emergency braking, and the polygonal wear of the tire shoulder has a negligible impact on the wheel hub’s dynamic stress. These results not only calculate the six-component force data of the tire but also break new ground in understanding the interaction between different factors and the wheel hub’s performance
Study on the variation mechanism of non-linear stiffness of rubber O-ring
Get PDFO-ring dampers can be used as vibration-damping elements for short-life, low-cost engines, and the selection of a suitable rubber superelastic-viscoelastic ontological model to study their stiffness and damping is an important prerequisite for determining their vibration-damping characteristics. The superelastic-viscoelastic constitutive model consists of two models, superelastic and viscoelastic, in which the superelastic model reflects the static characteristics of the O-ring. Therefore, it is the basis of the study of dynamic characteristics to carry out the research on the static stiffness of the O-ring and to select an accurate superelastic model to describe its deformation and recovery characteristics under different working conditions. Based on the fact that the O-ring is in a small deformation range in the damper and the applicability of finite element simulation, the Mooney-Rivilin superelastic constitutive model is selected in this paper. Establish a three-dimensional finite element model of the O-ring damper, focusing on the analysis of the effect of temperature on the O-ring material properties and damper structure, to reveal the mechanism of non-linear stiffness change of the O-ring damper. At the same time, the accuracy of the hyperelastic model is verified by the test method, which lays a foundation for the study of the dynamic stiffness and damping characteristics of the O-ring. The results show that in the pre-compression state, there is a large contact pressure between the O-ring and the inner and outer rings of the damper. The contact pressure increases linearly during the compression process, and the stiffness of the O-ring changes linearly. In the non-pre-compression state, the contact pressure is 0, the contact pressure increases nonlinearly during the compression process, and the stiffness of the O-ring shows obvious nonlinear characteristics. In addition, the static stiffness of the O-ring increases with the increase of pre-compression amount, increases with the increase of material hardness, and decreases with the increase of temperature. The above research provides a reference for selecting the appropriate O-ring material size and installation conditions in the project to ensure that the O-ring can effectively withstand pressure during use
Dynamic detection and evaluation of wheel flats in heavy-haul railway wheelsets using wayside monitoring systems
Get PDFIn recent years, heavy-haul railways have become a critical direction for freight transport in China, with wheel flats in wheelsets posing significant threats to operational safety and infrastructure integrity. Traditional detection methods (e.g., manual inspection, TPDS) suffer from low efficiency or limited accuracy in characterizing flat features. To address this, this study develops a rigid-flexible coupling dynamic model for C80 wagons with K6 bogies, uniquely integrated with field data from the Truck Operation Detection System (TODS) to bridge simulation and engineering application gaps. Focusing on wheel-rail force responses under wheel flat conditions, we establish a quantitative mapping relationship between flat length, vehicle speed, and impact force through polynomial fitting of simulation data (10-80 km/h for empty/loaded vehicles). To validate feasibility, a 56-channel wayside monitoring system (TODS) is installed on a heavy-haul railway, calibrated via hydraulic loading to ensure measurement accuracy. Field tests (80,541 vehicles monitored) confirm that TODS can infer flat length from detected impact forces, with results consistent with TPDS alarms but offering finer characterization of flat dimensions. This work provides a practical solution for real-time wheel flat detection, enhancing maintenance efficiency and safety in heavy-haul operations
Numerical simulation of a gas-flotation oil–water hydrocyclone separator
Get PDFEfficient oil–water separation of produced fluids from high water-cut oilfields requires significant improvement in hydrocyclone separation performance. In this work, computational fluid dynamics simulations were applied to analyze the influence of integrating gas flotation with hydrocyclone separation. To describe the internal flow behavior and the distribution of oil droplets in gas-assisted operation, the Mixture multiphase model together with the Realizable k-ε turbulence model was utilized. Based on a conventional liquid-liquid hydrocyclone, a porous medium region was incorporated into the large cone section to represent microporous walls for microbubble injection, thereby achieving the coupling of flotation and hydrocyclone separation. The results show that gas injection enhanced the separation efficiency from 83.56 % to 95.96 %. Moreover, microbubble size exhibited a pronounced influence on separation performance: smaller bubbles facilitated better oil-water separation. The optimal performance was obtained with an air bubble diameter of 5 μm, where the separation efficiency reached 97.73 %
Enhancing the Carrying capacity of complex mountain railway sections through the optimization of train mass standards
Get PDFIt is known that the current train mass standards for railway sections often do not allow locomotives to fully utilize their tractive power. This limits the throughput and Carrying capacity of the railway sections. This article examines the issues of increasing the carrying capacity of freight trains by optimizing train mass standards, using the “Angren-Pop” railway section, which has the most complex profile in “Uzbekistan Railways” JSC, as an example. Updated optimal train mass standards have been proposed for freight trains operating on the “Angren-Pop” railway section, and experimental tests have been carried out based on these standards, followed by their implementation in practice. Based on traction calculations, the interstation travel times of trains for the updated mass standards have been determined. Methods for effectively increasing the transport capacity of the section have been recommended by implementing measures such as increasing the train mass standards and interstation running speeds of freight trains, as well as systematically organizing the use of electric locomotives with high tractive power
Assessment of the influence of external dynamic factors on force loading of anchor bandage of traction electric motors
Get PDFA methodology has been proposed for calculating the force loading of anchor bandages of locomotive traction electric motors from the action of external dynamic factors, which makes it possible to determine dynamic stresses in each section of the anchor bandage along its entire length, depending on the operating modes of the traction electric motor, taking into account its design features and real operating conditions. It has been established that the most significant influence on the fluctuations of the armature shaft of traction electric motors of diesel locomotives is exerted by dynamic influences from the collision of wheels with joints and unevenness of the rail track, as well as from errors in the manufacture of the serrated broadcast (gears). The supposed economic effect from the creation of new glass bandage designs for the anchors of traction electric motors of diesel locomotives of the 2TE10M series is estimated at approximately 10.92 million soums for one such diesel locomotive. It is recommended to continue these studies in order to develop and justify rational geometric parameters of a new design of the anchor glass bandages of a traction electric motor with increased fatigue strength
Small targets detection in low-resolution remote sensing images based on super-resolution joint optimization
Get PDFWhile convolutional neural networks have driven remarkable progress in remote sensing object detection, persistent challenges remain in detecting small targets within low-resolution imagery due to their limited pixel representation and feature degradation during hierarchical downsampling. To address this, this study proposed the joint super-resolution and detection network (JSRDN), which synergistically optimizes SR reconstruction through task-specific detection feedback, significantly enhancing small target recognition in LR remote sensing imagery. Firstly, generator in generative adversarial network incorporates improved residual blocks, enabling enhanced perception of complex deep-level features in the SR reconstruction process. Then, a perceptual loss function is introduced into the adversarial training process, which captures perceptual discrepancies in high-level features between reconstructed images and original HR references. After that, an edge-enhancement network is designed to dynamically detect edges in intermediate features restored by the generator, prioritizing edge influence across network layers to generate discriminative features for target recognition. Furthermore, the JSRDN implements detection-driven feedback by backpropagating object recognition loss through the generator, enforcing the super-resolution process to prioritize detection-salient feature recovery. Evaluated on 64×64 low-resolution COWC datasets, JSRDN achieves 0.1819 dB peak signal-to-noise ratio (PSNR) and 7.18 % average precision (AP) improvements over the deep residual dual-attention network (DRDAN), with ablation studies and visualizations confirming its balanced optimization of reconstruction fidelity and detection-oriented feature learning. This technology can provides valuable support for small target measurement and opens new opportunities in the field
Dynamic response characteristics of shallow-buried biased small clearance tunnel subjected to various ground shaking
Get PDFThe axial force and bending moment of tunnel lining are crucial for lining stability. To investigate the response patterns of axial force and bending moment in shallow-buried biased small clearance tunnels under various conditions – including different adjacent slope angles, loading wave types, peak loads, and loading directions – extensive numerical simulations were conducted. The numerical results were subsequently verified through large-scale vibration table physical model experiments. The findings reveal that the variation patterns of lining axial force and bending moment under bidirectional coupled seismic waves demonstrate similarity to those under vertical seismic waves. Vertical seismic motion exerts a more pronounced influence on lining axial force response. Seismic wave peak intensity significantly affects lining axial force and bending moment, with both parameters showing gradual increases corresponding to peak load escalation. The arch shoulder of the slope-side right tunnel lining exhibits particularly strong axial force and bending moment responses. While Darui wave, Wenchuan wave, and Kobe wave produce essentially consistent axial force and bending moment response patterns in tunnel linings, their magnitudes differ substantially. Seismic wave type primarily influences response magnitude rather than characteristic patterns of axial force distribution. Increasing slope angles adjacent to tunnels correlate with heightened axial force and bending moment responses in linings. A logarithmic functional relationship exists between slope angle and response values at the lining arch shoulder. These findings provide valuable references for seismic design of shallow-buried biased small clearance tunnels