Dynamics Investigation on Axial-Groove Gas Bearing-Rotor System with Rod-Fastened Structure

This research report discusses the dynamic behaviors of an axial-groove gas bearings-rotor system with rod-fastened structure. The time-based dependency-compressible Reynolds equation in the gas bearing nonlinear system is solved by the differential transformation method, and the continuous gas film forces of a three-axial-groove gas bearing are obtained. A dynamic mathematical model of the rotor system with rod-fastened structure supported in two- and three-axial-groove gas bearings with eight degrees of freedom is established. The dynamic motion equation of the rod-fastened rotor system is solved by the modified Newmark-β method based on disturbance compensation, which can reduce the computing error and improve computing stability. The dynamic characteristics of the rod-fastened rotor-gas bearing system are analyzed efficiently by the diversiform unbalance responses. The influence of the position angle of the pad on the nonlinear characteristics of the rod-fastened rotor system is also studied.

METHOD FOR STEP-BY-STEP ADAPTATION OF THE WIDTH OF MEASUREMENT INTERVAL TO SIGNAL PARAMETERS

Указывается, что известные методы измерений исходного сигнала приводят к погрешностям, если ширина измерительных интервалов пошагово не адаптируется к меняющимся параметрам сигнала. Использован новый подход к измерению, раскрывающий единую физическую основу измерения и инструментального вычисления. Алгоритм, следствие указанного подхода, предназначен для получения дискретной последовательности отсчетов сигнала, соответствующих локально определяемым интервалам усреднения. Последовательность получаемых интервалов усреднения приближается к оптимальной и обеспечивает при измерении или решении вычислительной задачи уменьшение погрешности изменяющейся величины. Приведены результаты моделирования на трёх массивах отсчётов с фиксированными и адаптируемыми интервалами усреднения. It is indicated that the known methods for measuring some initial signal lead to errors if the width of the measuring intervals does not step by step adapt to changing signal parameters. A new approach to measurement is used, revealing a unified physical basis for measurement and instrumental computation. A new algorithm as a consequence of this approach is designed to obtain a sequence of discrete samples that matched to locally determined averaging intervals. Resulting sequence of averaging intervals ensures a decrease in the measurement or computing error. The results of calculations on three arrays of samples are presented with fixed and adaptable averaging intervals.

Метод расчета спектральных характеристик по сигналам малой длительности и нестационарным процессам

We propose a method of estimating spectral properties of a system from short signals and processes with varying characteristics, which is based on the wavelet-transform modulus-maxima method. It is shown that this approach allows significant reduction of the computing error as compared with the classical spectral analysis.

A Novel Analytical Method for Designing Microelectromechanical Filters

This work presents a novel analytical model for designing resonator-based MEMS filters, which eliminate the computing error caused by material parameters and generates more reliable theoretical model. This model is comfired by a composite-array filter in the work. Furthermore, this model can be applied for MEMS filters formed by any type of resonators, the geometries of the mechanical coupling beams are determined with high precision.