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Recently, modern intelligent fault diagnosis algorithms based on deep learning have been widely used to recognize the health state of rolling bearings. However, the constantly varying load in real industry leads to unsatisfactory diagnosis results. How to make the models effectively diagnose the health state of rolling bearings under varying loads is a key issue. In this paper, an Adaptive Attention Network (AANet) is proposed to resolve the issue. That the interference is introduced by the Multi-scale Convolution Module with wide kernels (MCM) at the head of the AANet is the premise for extending the model to other loads. And the Adaptive Attention Modules (AAMs) embedded in the AANet distinguishe state-related features and unrelated features, which enhances the diagnostic ability of the model across loads. In order to verify the effectiveness of the algorithm, experiments have been performed on a public data set. Experimental results show that the average accuracy of this algorithm achieves 0.976, which can effectively recognize the health state of rolling bearings under varying loads, compared to other algorithms. [ABSTRACT FROM AUTHOR]

This study presents an improvement of the graphical method for plotting the shear and moment diagrams for the structural members under linearly varying loads (triangular and trapezoidal loads). Based on the parabolic nature of the shear function, when the loading varies linearly, and on the relations among load, shear, and moment, a mathematical equation is developed to locate the zero-shear point, while a geometric technique is presented to calculate the parabolic shear area. Five comprehensive examples of beams loaded with linearly varying loads are selected to illustrate the steps of the solution for the proposed techniques. The results demonstrated the applicability of the presented method, and gave exact diagrams compared with the basic graphical method. It is concluded that the proposed improved method is generally more convenient, less time-consuming, and has less computational efforts because it does not require sectioning, solving equilibrium equations, and quadratic formulas compared with the basic graphical method.

This paper focuses on the learning-based motion control for flexible manipulators with varying loads via the singularly perturbed technique. Considering the two-timescale feature of the flexible manipulator, system dynamics are decomposed into fast and slow subsystems, and corresponding sub-controllers are designed with robust adaptive dynamic programming (RADP) and robust sliding mode control (RSMC) methods, respectively. In the proposed composite control framework, an RADP-based sub-controller is developed to realize the trajectory tracking and alleviate the parametric uncertainty utilizing rotating angles in the slow timescale, while an RSMC sub-controller is introduced to improve the vibration suppression in the fast timescale. Finally, the stability of the closed-loop system is guaranteed, and simulations are carried out to show the effectiveness of the proposed control algorithm. [ABSTRACT FROM AUTHOR]

In this paper, a generalized nonlinear extended state observer is applied to an integral sliding mode (ISM) tracking control method for a pneumatic cylinder servo system with varying loads. The observer is established to estimate the total disturbance and its derivative for the system. An ISM controller is designed to ensure control performances of the system. Both finite-time convergence of the observer and finite-time stabilization of the closed-loop system are realized using Lyapunov’s stability theory. Lastly, experimental results demonstrate that control precision and response rapidity are improved using the proposed method. [ABSTRACT FROM AUTHOR]

Studying the dynamic performance is very important for improving the performance of the electrical machines. The sudden applied or removal the load is very critical for the electrical machines. It may lead to some problems in it's as, mechanical stress, surge current, increase the losses and decrease the motor life time. So, this paper studied this problem and constructed proposal model to reduce the effect of this problem on the electrical machines. This occurred through comparing between the effect of the dynamic load, sudden applied and removal loads on the performance characteristics of interior permanent synchronous motor (IPMSM) with proposal model and with classical model in the constant flux region and in the field weakening region. The simulation is done through the MATLAB program. The simulation shows the effectiveness of the proposal model on the performance characteristics of the IPMSM. With proposal model, the overshooting and under shooting of the motor speed are reduced. Rise time and settling time are improved, the response of the motor torque for load variations is improved and the stator currents are decreased. In this model, the space vector pulse width modulation is used to controlling the inverter which used to drive the IPMSM. [ABSTRACT FROM AUTHOR]

In this article, aiming at handling the trajectory tracking issue of industrial manipulator system (IMS) with modeling uncertainty, varying loads (VL) and unknown dead-zone characteristic, a compensation-based adaptive switching controller synthesis is proposed. In this scheme, the dynamic model of the IMS under VL is regarded as a switched system (SS) with a specified modal set. The nonlinear term related to plant model in each subsystem is approximated by radial basis function neural network (RBFNN) so as to avoid the reliance of the controller on the accurate model, and the unknown dead-zone is estimated and compensated by NN, from which the corresponding NN robust compensation term is developed to eliminate the potential perturbations and estimated errors. The designed controller with switching mechanism effectively solves the problem of degradation of the tracking accuracy caused by VL. Finally, the uniform ultimate boundedness of error signals is analyzed by the average dwell time (ADT) approach, multi-Lyapunov function method and the synthesized adaptive control law, and the effectiveness of the developed scheme is verified by simulation. [ABSTRACT FROM AUTHOR]

A rigid punch pressed against an incompressible half-plane by a constant normal load is subject to both a cyclically varying shearing force, and a synchronously varying underlying bulk tension. The evolution of the slip/stick distribution along the contact interface is found during a loading cycle. An asymptotic approach is subsequently used to determine the order of singularity, and hence spatial distribution of the local stress state. A generalised stress intensity factor is then defined to scale the corresponding asymptotic solution, and hence map out the evolution of the process zone. The analysis shows that there is a smooth transition in the form of the asymptotic solution in moving from an ‘adhered’ contact edge to a ‘slipping’ contact edge, and vice versa. The implications of the results to fretting fatigue are discussed. [Copyright &y& Elsevier]