Identification of Physical and Excitation Parameters of Under-Chassis Equipment for Railway Vehicles

The accuracy of the physical parameters and excitation parameters of the under-chassis equipment has a significant impact on investigations of the coupled vibration of the vehicle body and the under-chassis equipment. In this study, an equipment vibration isolator test bench is used to develop a physical parameter identification method based on the free vibration acceleration response of the equipment and an excitation parameter identification method based on the forced vibration acceleration response. The equipment mass parameter and the center of the gravity position parameter can be obtained first through a static load test, and then, the inertia parameters can be obtained through a dynamic test. Identification of the excitation parameters of the equipment is based on the physical parameters and the acceleration response. The accuracy of the physical parameters directly affects the excitation parameter identification results. The larger the frequency ratio, the smaller the identification error will be, and the larger the damping ratio, the larger the identification error will be. The identification test results of single-frequency excitation and multifrequency excitation show that the proposed excitation parameter identification method has high accuracy.

Computational Optimization of the Radial and Spiral Distortion Aberration Coefficients of Magnetic Deflector

The optimum design of the magnetic deflector with the lowest values of the radial and spiral distortion aberration coefficients was computed. The optimized calculations were made using three models, Glaser bell-shaped, Grivet-lenz and exponential models. By using the optimum axial field distribution, the pole pieces shape which gave rise to those field distributions was found by using the reconstruction method. The calculations show that the results of the three models coincide at the lower values of the excitation parameter. In general the Glaser- bell shaped model gives the optimum results at the whole range of the excitation parameter under investigation.The negative values of the spiral distortion aberration coefficient appears in the results at the same case, therefore the designer can use it as corrector in other optical systems which suffer from this type of aberration

Variation Analyses Using SugarCube

In this paper, we present new variation analysis features added to SugarCube. SugarCube is a novice-friendly online CAD tool for exploring the design space of compact MEMS models. Such variation analysis can help to evaluate the bounded effects of unavoidable process variations during the fabrication (such as Young’s modulus, overcut, gap asymmetry, etc.), packaging (such as variations in temperature, expansion coefficients, etc.), and operation (such as variations in voltage sources, etc.). Compared to other software tools for MEMS, the benefits of variation analysis in SugarCube include its comprehensiveness, ease of use, speed, and accessibility. In SugarCube, any geometric, material, or excitation parameter may be easily explored for its effect on device performance. Such analysis is expected to benefit feasibility analyses on process survivability, process yield, and operational robustness. For a couple of test cases, we perform our variation analysis on a micro-scale accelerometer and gyroscope.