Canonical-parameter estimation for instrument complex frequency response

1993 ◽  
Vol 36 (9) ◽  
pp. 968-972
Author(s):  
V. Ya. Kreinovich ◽  
G. N. Solopchenko
Keyword(s):  
Parameter Estimation ◽  
Frequency Response ◽  
Complex Frequency ◽  
Canonical Parameter

scholarly journals The PolyMAX Frequency-Domain Method: A New Standard for Modal Parameter Estimation?

2004 ◽  
Vol 11 (3-4) ◽  
pp. 395-409 ◽  
Author(s):  
Bart Peeters ◽  
Herman Van der Auweraer ◽  
Patrick Guillaume ◽  
Jan Leuridan
Keyword(s):  
Parameter Estimation ◽  
Frequency Response ◽  
Least Squares ◽  
Frequency Domain ◽  
Real Life ◽  
Mode Shapes ◽  
Frequency Domain Method ◽  
Complex Frequency ◽  
Modal Parameter ◽  
Domain Method

Recently, a new non-iterative frequency-domain parameter estimation method was proposed. It is based on a (weighted) least-squares approach and uses multiple-input-multiple-output frequency response functions as primary data. This so-called “PolyMAX” or polyreference least-squares complex frequency-domain method can be implemented in a very similar way as the industry standard polyreference (time-domain) least-squares complex exponential method: in a first step a stabilisation diagram is constructed containing frequency, damping and participation information. Next, the mode shapes are found in a second least-squares step, based on the user selection of stable poles. One of the specific advantages of the technique lies in the very stable identification of the system poles and participation factors as a function of the specified system order, leading to easy-to-interpret stabilisation diagrams. This implies a potential for automating the method and to apply it to “difficult” estimation cases such as high-order and/or highly damped systems with large modal overlap. Some real-life automotive and aerospace case studies are discussed. PolyMAX is compared with classical methods concerning stability, accuracy of the estimated modal parameters and quality of the frequency response function synthesis.

Analytical representation of hydrophone complex frequency response

2021 ◽  
pp. 16-20
Author(s):  
Alexander E. Isaev
Keyword(s):  
Frequency Response ◽  
Complex Variable ◽  
Active Element ◽  
Analytical Representation ◽  
Complex Frequency ◽  
Minimum Phase ◽  
Experimental Frequency ◽  
Resonance Properties ◽  
Fractional Rational Function ◽  
Sound Diffraction

The problem of analytical representation of hydrophone complex frequency response based on a model consisting of an advance line and a minimum-phase part, which describing the effect of sound diffraction and resonance properties of an active element, is considered. Algorithms are proposed for approximating the hydrophone complex frequency response by a fractional-rational function of the complex variable according to the data of the hydrophone amplitude-frequency and/or phasefrequency responses. Examples of the application of these algorithms for processing experimental frequency characteristics of hydrophones are given.

Experimental Study for Extraction of Normal Modes

1995 ◽  
Author(s):  
S. Y. Chen ◽  
M. S. Ju ◽  
Y. G. Tsuei
Keyword(s):  
Frequency Response ◽  
Normal Mode ◽  
Normal Modes ◽  
Measurement Data ◽  
Mode Shapes ◽  
Complex Frequency ◽  
Response Functions ◽  
Frequency Response Functions ◽  
Incomplete System ◽  
Coupled Structures

Abstract A frequency-domain technique to extract the normal mode from the measurement data for highly coupled structures is developed. The relation between the complex frequency response functions and the normal frequency response functions is derived. An algorithm is developed to calculate the normal modes from the complex frequency response functions. In this algorithm, only the magnitude and phase data at the undamped natural frequencies are utilized to extract the normal mode shapes. In addition, the developed technique is independent of the damping types. It is only dependent on the model of analysis. Two experimental examples are employed to illustrate the applicability of the technique. The effects due to different measurement locations are addressed. The results indicate that this technique can successfully extract the normal modes from the noisy frequency response functions of a highly coupled incomplete system.

A framework for high-resolution frequency response measurement and parameter estimation in microscale impedance applications

Measurement ◽  
2019 ◽  
Vol 148 ◽  
pp. 106913 ◽  
Author(s):  
Roberto G. Ramírez-Chavarría ◽  
Matias I. Müller ◽  
Robert Mattila ◽  
Gustavo Quintana-Carapia ◽  
Celia Sánchez-Pérez
Keyword(s):  
Parameter Estimation ◽  
High Resolution ◽  
Frequency Response ◽  
Response Measurement ◽  
Frequency Response Measurement

Transfer Functions of One-Dimensional Distributed Parameter Systems by Wave Approach

2006 ◽  
Vol 129 (2) ◽  
pp. 193-201 ◽  
Author(s):  
B. Kang
Keyword(s):  
Transfer Function ◽  
Frequency Response ◽  
Wave Reflection ◽  
Transfer Functions ◽  
Distributed Parameter Systems ◽  
Distributed Parameter ◽  
Complex Frequency ◽  
Reflection And Transmission ◽  
One Dimensional ◽  
Analysis Technique

An alternative analysis technique, which does not require eigensolutions as a priori, for the dynamic response solutions, in terms of the transfer function, of one-dimensional distributed parameter systems with arbitrary supporting conditions, is presented. The technique is based on the fact that the dynamic displacement of any point in a waveguide can be determined by superimposing the amplitudes of the wave components traveling along the waveguide, where the wave numbers of the constituent waves are defined in the Laplace domain instead of the frequency domain. The spatial amplitude variations of individual waves are represented by the field transfer matrix and the distortions of the wave amplitudes at point discontinuities due to constraints or boundaries are described by the wave reflection and transmission matrices. Combining these matrices in a progressive manner along the waveguide using the concepts of generalized wave reflection and transmission matrices leads to the exact transfer function of a complex distributed parameter system subjected to an externally applied force. The transient response solution can be obtained through the Laplace inversion using the fixed Talbot method. The exact frequency response solution, which includes infinite normal modes of the system, can be obtained in terms of the complex frequency response function from the system’s transfer function. This wave-based analysis technique is applicable to any one-dimensional viscoelastic structure (strings, axial rods, torsional bar, and beams), in particular systems with multiple point discontinuities such as viscoelastic supports, attached mass, and geometric/material property changes. In this paper, the proposed approach is applied to the flexural vibration analysis of a classical Euler–Bernoulli beam with multiple spans to demonstrate its systematic and recursive formulation technique.

Coupling Sound Absorbing Materials With an Air Cavity Using Frequency Dependent Bulk Material Properties

2016 ◽  
Author(s):  
Shung H. Sung ◽  
Donald J. Nefske
Keyword(s):  
Finite Element ◽  
Frequency Response ◽  
Material Properties ◽  
Complex Frequency ◽  
Air Cavity ◽  
Frequency Dependent ◽  
Absorbing Materials ◽  
Mode Method ◽  
Modal Solution ◽  
Solution Methodology

This paper presents the acoustic finite element method and the modal solution method for coupling sound absorbing materials with an air cavity to predict the sound pressure frequency response. The sound absorbing materials are represented with complex, frequency-dependent, effective mass-density and bulk-modulus properties obtained from the acoustic impedance of material samples. To couple the sound absorber cavity and air cavity, the boundary conditions at the interface between the cavities requires equality of pressure and equality of acoustic volume flow. Two modal solution methods are developed to compute the frequency response of the coupled system with frequency dependent material properties: the component mode method and the coupled mode method. The finite element and modal solution methodology is developed in a form readily adaptable for implementation in commercially available codes. The accuracy of the modal solution methodology is assessed for modeling a one-dimensional air tube terminated with absorbent material and the seats in an automobile passenger compartment.

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