Wheel out of round, which has a significant influence on the ride comfort of vehicles, is very difficult to detect, especially for vehicles with rubber tires like a monorail. The prominent feature of wheel eccentricity caused by wheel out of round is that there will be a dominant frequency of the vehicle acceleration that varies with the speed of the vehicle, while the wavelengthes are all equal to the wheel circumference. By studying the experimental results of Chongqing straddle monorail, an indirect detection method of the wheel out of round is put forward. Then a simulation model of the monorail vehicle under the influence of the wheel out of round is established. The numerical analysis and experimental results lead to that the main reason for the abnormal vibration of the vehicle is the wheel out of round. Through the analysis of the vertical dynamic equation of the monorail system, all other factors that may affect the dominant frequency of vehicle vibration are analyzed. Finally, it is concluded this abnormal vibration caused by wheel out of round can only be reduced by increasing the vertical stiffness of the air spring and car body mass other than changing wheels.
Solving the power flow problem in a distributed fashion empowers different grid operators to compute the overall grid state without having to share grid models-this is a practical problem to which industry does not have off-theshelf answers. In cooperation with a German transmission system operator we propose two physically consistent problem formulations (feasibility, leastsquares) amenable to two solution methods from distributed optimization (the Alternating direction method of multipliers (admm), and the Augmented Lagrangian based Alternating Direction Inexact Newton method (aladin)); with aladin there come convergence guarantees for the distributed power flow problem. In addition, we provide open source matlab code for rapid prototyping for distributed power flow (rapidpf), a fully matpower-compatible software that facilitates the laborious task of formulating power flow problems as distributed optimization problems; the code is available under https://github.
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