Precision Machining Equipment Fault Diagnosis Based on CWT and Improved ResNeXt

A fault diagnosis method based on continuous wavelet transform and improved multi-dimensional residual network was proposed to solve the problem that the working environment of precision machining equipment is very complicated,and the fault characteristic signal is weak and hard to extract.Firstly,the best wavelet base Cmor 3-3 is selected by comparing 6 different wavelet base types.Secondly,continuous wavelet transform(CWT)is applied to the acquired original vibration signal to generate the feature map and process the gray level.Finally,the improved ResNeXt network is used to diagnose faults in precision machining equipment.The experimental results show that the proposed CWT and the improved ResNeXt algorithm have high accuracy in identifying precision machining equipment faults in complex environments,with an average accuracy of 99.4%。

Analysis on the Failure Causes of the Collapsed Tubing in an Oil Well

Due to the influence of multiple factors such as internal and external formation and mechanical pressure, medium corrosion and construction operation environment, a tubing collapse failure occurred in an oil well. In order to determine the failure cause of the tubing, physical and chemical tests and mechanical properties analysis were carried out on the failed tubing sample and the intact tubing. The results show that the chemical composition, ultrasonic and magnetic particle inspection, metallographic test, Charpy impact energy and external pressure mechanical property test of the failed tubing all meet the requirements of API Spec 5CT-2021 standard, but the yield strength of the failed tubing does not meet the requirements of API Spec 5CT-2021 standard. Through the analysis of the working conditions, it can be seen that the anti-extrusion strength of the tubing collapse does not meet the API 5C3 anti-extrusion strength standard. The failure type of the well tubing is tubing collapse caused by large internal and external pressure difference.

Attack and Defense Strategies in Complex Networks Based on Game Theory

To investigate the attack and defense strategies in complex net works,the authors propose a two-player zero-sum static game model with complete information which considers attack and defense strategies simultaneously.The authors assume that both the attacker and defender have two typical strategies:Targeted strategy and random strategy.The authors explore the Nash equilibriums of the attacker-defender game and demonstrate that when the attacker's attack resources are not so significantly abundant as the defender's resources,there exists a pure-strategy Nash equilibrium in both model net works and real-world net works,in which the defender protects the hub t arge ts with large degrees preferentially,while the attacker prefers selecting the targets randomly.When the attack resources are much higher than defense resources,both the attacker and the defender adopt the targeted strategy in equilibriums.This paper provides a new theoretical framework for the study of attack and defense st rat egies in complex net works.