Journal of Mechanical Engineering, Automation and Control Systems
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Research on high-speed railway vehicle emergency braking control based on rail surface foreign matter identification
Get PDFIn order to improve the operation stability of high-speed railway vehicles, an emergency braking control method for high-speed railway vehicles based on the identification of foreign matters on the track surface is proposed. The dynamic frame scanning method is used to build the image acquisition of abnormal objects on the high-speed rail track surface, and the visual sensor and vibration sensor are used to identify and process the features of foreign objects on the high-speed rail track surface. According to the abnormal feature extraction results, the command signal in case of foreign objects is transmitted to the terminal command library of the braking control system. According to the transfer switch of the emergency braking system to display the main emergency disposal output states such as the train emergency disposal information reception, emergency disposal level, emergency disposal type and other information, the joint control method of contact pressure distribution and non-uniform heat flux is adopted, and the joint control method of control system, drive system, disc friction system and signal acquisition system is adopted. The emergency braking control module is established to realize the emergency braking control of high-speed railway vehicles according to the feature recognition results of foreign matters on the rail surface. The test results show that the control module is less affected by the vehicle wheelbase characteristics, track structure characteristics and other factors when using this method for high-speed railway vehicle emergency braking control, and has a strong ability to identify the characteristics of foreign matters on the track surface, which improves the stability and real-time performance of emergency braking
Experimental study and comparative analysis of pitting fault in spur gear system
Get PDFThis paper uses a dynamic six-degree-of-freedom model that considers torsional and lateral motions to predict the impact of pitting on vibration parameters in a spur gearbox for various operating speeds and torque loads. The study examines the dynamic characteristics of a gearbox with localized pitting damage on a single gear tooth using theoretical and experimental approaches. The research analyzes the forced vibrations of a single-stage spur gear system with pitting damage, which includes variations in mesh stiffness, damping, and gear error excitation, to identify symptoms of default. The equation of motion for the rotary gearbox system is established using the Lagrangian method in tandem with Short-Time Fourier Transform (STFT) and frequency-RPM map fault diagnosis. During real-time vibration monitoring, vibration signals are captured via accelerometers and processed in both the time and frequency domains using the LabVIEW data acquisition signal processing package to extract diagnostic information. The experimental findings demonstrate how vibration analysis combined with time-frequency processing can recognize machine conditions even in harsh operational conditions. Moreover, the experimental results indicate a significant similarity with the theoretical analysis and validate the effectiveness of the RPM frequency technique-based pitting detection method, which can be an asset in gear fault monitoring
An efficiency calculation model for ball screws by accounting for lead errors
Get PDFTransmission efficiency is a pivotal indicator, providing a comprehensive view of the overall performance of a ball screw. While extensive research has predominantly focused on computing transmission efficiency across various operating conditions, the factors influencing the variability have often been overlooked. This study introduces an innovative method for computing transmission efficiency, which considers lead error, drawing on deformation coordination theory and load distribution. Multiple ball screws of varying precision grades underwent rigorous testing to quantify lead errors. Subsequently, each screw was matched with an identical set of nuts to measure the respective transmission efficiencies. Experimental results reveal a linear correlation between lead error and transmission efficiency when both lead error and uneven ball load distribution in ball screws are considered. The relative error between the calculated transmission efficiency results and experimental values for ball screws of different precision grades falls within the range of 0 % to 7.42 %, confirming the validity of the proposed model in this paper
Do chewing simulators influence the test results of dental materials? Systematic review
Get PDFInvestigate whether different results about the physical properties of the same biomaterial frequently found in the literature are due to chewing simulator deficiency. A literature review was performed by searching for data on indicators of test accuracy, reproducibility, maintenance of test parameters during all experiments, and standards in the articles or in the sites of manufacturers. The database searched was CAPES PORTAL, and the keywords used were “bite force” AND “simulator”, “chewing simulator” and “mastication simulator”. Including criteria for the papers are publication filter date of “January 1, 2016”, articles in English, Spanish and Portuguese language were accepted. The first 100 papers that seemed suitable when considering the title and abstract were recovered. Only one simulator used for food property studies had the parameters searched. In the customized simulators for biomaterial properties, only one showed standards, and 8 showed all other parameters searched. All manufactured simulators showed all parameters searched, and only two manufactures did not show standards. Based on the data obtained, the disparate results of experiments with dental materials appeared to be more related to the test conditions than to the testing machines. Knowledge Transfer Statement The findings of the current review suggest that the chewing simulators used in preclinical research are reliable, bringing safety to restorative processes regarding the material. Any difference in preclinical investigations about dental material physical properties is due to test conditions other than chewing simulators
Modern development of metamaterials for obtaining special electromagnetic, acoustic, mechanical and vibration-isolating properties
Get PDFThe article presents the history of the development of metamaterials, which begins with the development of metamaterials to obtain unique electromagnetic properties. The first ideas of such materials appeared in the XIX century. Such constructions make it possible to obtain a negative permittivity, and further the “invisibility effect”. The idea of creating a material with a given microstructure also makes it possible to obtain metamaterials with a negative Poisson’s ratio, acoustic metamaterials. Separately, it should be noted that such an approach makes it possible to obtain metamaterials with negative rigidity and vibration-isolating metamaterials. The article presents the author's design of a vibration-isolating metamaterial with quasi-zero stiffness. A demonstration prototype was made
Six-DOF modular robotic arm bearing chatter suppression algorithm
Get PDFRobotic arms are frequently utilized in contemporary industrial production since they offer great qualities like high precision and low mass. How to minimize robotic arm tremors in order to maximize their control effect has emerged as one of the most critical issues to be resolved with the continued development of industrial intelligence. The study uses a combination of PID control and an artificial fish swarm technique to optimize the parameters and confirm the simulation control effect based on the kinematic analysis of a six-degree-of-freedom (Six-DOF) modular robotic arm. The findings demonstrated that the suggested fusion approach converges to zero in 80 iterations and has a recall of 0.893 and 0.785 at an accuracy of 0.8 and 0.9, respectively. The robotic arm control system’s average control effect is 42.96 %, which is a respectable control performance. In the second and third studies, the fusion approach stabilized actuator end tremor suppression after 0.01 s and 0.0001 s, respectively. It shows that the technique can effectively suppress robotic arm bearing tremor and has high flexibility for robotic arm tremor suppression, which offers trustworthy technological support for improving the motion control system of industrial robots
Joint effects of thermal diffusion and diffusion thermo on MHD three dimensional nanofluid flow towards a stretching sheet
Get PDFThis communication reports the joint effects of Thermal Diffusion and Diffusion Thermo on viscous and incompressible three-dimensional nanofluid flow towards a stretching sheet in connection to the influence of a magnetic field. In this study, nanofluid model is employed for the effects of thermophoresis and Brownian motion. Following that, similarity variables are chosen to turn the dimensional nonlinear system into dimensionless expressions and the resultant transformed equations are solved numerically using Finite Element method. Special emphasis has been given to the parameters of physical interest. These findings are visually presented through graphical representations, providing a clear and insightful understanding involved in this flow scenario. In addition, the final results are examined in light of past research and it is determined that they meet the convergence standards to an exceedingly satisfactory degree. The study’s findings are beneficial for many technical and commercial endeavours
Application of optimized CNN algorithm in landslide boundary detection
Get PDFLandslide, as a natural geological phenomenon with great harm, seriously threatens human social activities and life safety. It has a variety of latent and immeasurable destructiveness, which has a significant impact on the economic losses in rural areas. Therefore, it is urgent to take measures to accurately identify landslides to reduce their negative impacts. However, traditional manual visual interpretation has been unable to meet the current needs for emergency rescue of landslides, so computer intelligent methods have been paid attention to. This study proposes a new recognition network to address the problem of low accuracy of intelligent landslide boundary recognition methods. Firstly, the experiment incorporated boundary structure information into the Full Convolutional Network (FCN) for optimization, and constructed an Improved Full Convolutional Network (IFCN) model to better achieve image reconstruction. After that, Attention Mechanism (AM) is further introduced to achieve accurate detection of landslide boundaries in images, namely the IFCN-AM model. The attention mechanism introduced include spatial attention mechanism and multi-channel attention mechanism. Both are responsible for enhancing the language representation ability of the model and aggregating the interrelated features between different channels. The experimental results show that IFCN-AM has a 3 % to 7 % improvement in accuracy, recall, F1 value, and MIoU value
Overview of the prospects for the introduction of ultrasonic oil treatment in the main pipeline transport
Get PDFThis paper considers the most common methods of pipeline transport of high solidified oil existing at the moment. The effects of treating oil with magnetic and electric fields are given. The positive and negative effects of ultrasonic treatment in oil transport processes are considered. The totality and quality of the facts requires much more in-depth analysis on a number of issues in this area because with a lot of positive effects are present and negative, which do not allow to implement
Vibration influence of different types of heavy-duty trucks on road surface damage
Get PDFUnder the interaction of the wheels of heavy-duty trucks on the random road surface when the vehicles are travelling, their generated vibrations not only affect the driver's ride comfort but also impact the road surface damage. To assess the vibration influence of different types of vehicles on the road surface damage, three dynamic models of the two axle, three axle, and four axle of heavy trucks have been build and computed via the Matlab/Simulink software. The dynamic tire load, dynamic load coefficient, and dynamic load-stress factor are chosen to assess the friendly load of different heavy trucks under the different operating conditions of the vehicle. The obtained result indicates that the dynamics parameters including suspension system, tires, and axle load distributions of heavy trucks have a greater effect on the dynamic tire force than the total weight of the vehicle. In order to ensure the road’s safety, the traffic management should intervene quickly to give a velocity limit for vehicles under the condition of the vehicle moving with the empty loaded on the poor road surface