Appraisal of contact stresses, surface cracks, and plastic deformations in rails and wheels has always been an important issue in mechanical and railway engineering because of two main reasons. In the first place, these inappropriate events lead to the reduction of service life of the railway track. Besides, studying railway systems requires both time-consuming analysis methods and expensive experimental works. In this paper, a railway system containing wheel, rail, axle, and pads is modeled and analyzed. Using elastic-plastic materials, mapped meshing, and the rolling motion of the wheel contingent upon the up-to-date international railway systems results in high accuracy in the solutions of this problem. ANSYS software is utilized with the purpose of simulating the system. The contribution of this study is on the basic way of managing Rail-Wheel interaction problems from a finite element method point of view. So, stress distribution, elastic and plastic strains as well as nodal forces are considered, simultaneously. The results obtained from the simulation have suitable agreement with the real life experiences. Another feature of this paper is that it demonstrates essential steps for more realistic 3D solutions to the aforementioned problems.

It has been seen that semiactive magnetorheological (MR) dampers are not sometimes reliable when employed in the building to contract acceleration demand of the stories. In the current paper, a three-storey sample building with semiactive MR dampers subjected to harmonic base excitation is taken under examination to clarify the reliability of such semiactive control systems in mitigation of absolute acceleration response of the buildings. Comparison between semiactively controlled building and uncontrolled original building is chosen as an implicit reliability limit-state function. Firstly, first-order reliability method (FORM) is engaged to examine the reliability of the system by linearizing the chosen nonlinear limit-state function. Afterwards, Monte Carlo simulation (MCS) is used to verify the obtained results by FORM method.

The application of the general flying‐inductor (FI) cell in two novel transformerless photo‐voltaic (PV) inverters are proposed and investigated. The simultaneous step up and down ability is possible with both topologies, while a high conversion efficiency and a high‐quality AC current are achieved. The leakage current problem, which is a main concern with the transformerless PV inverters, is also considered. One of the proposed topologies presents a higher efficiency, while the other one provides the high quality of injected current with the lowest number active switches. The current control, especially at transition modes of operation is highly improved by utilizing a fast response dead‐beat control scheme. The working principles of the proposed converters are explained in details and 0.88‐kW experimental prototypes are implemented to confirm the theoretical achievements. Finally, a comparison with other existing topologies has been investigated for better clarification of the advantages and disadvantages of the proposed inverters.

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