Comparison of Different Estimation Algorithms Used in the Experimental Determination of Modal Parameters

2015 ◽  
Vol 816 ◽  
pp. 412-415
Author(s):  
Róbert Huňady ◽  
Martin Hagara ◽  
Peter Pavelka
Keyword(s):  
Circular Cross Section ◽  
Extraction Methods ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Polynomial Method ◽  
Laser Vibrometer ◽  
Estimation Algorithms ◽  
Freely Suspended ◽  
Rational Fraction Polynomial

The paper deals with the estimation of modal parameters and its main purpose is to compare differences in the values of natural frequencies and damping ratios, which were estimated using three different extraction methods: Rational Fraction Polynomial method, Complex Mode Indicator Function and Polyreference Time Domain Technique. These methods are well suited to the more general application to multi-FRF data, both of the SIMO and the MIMO types. The object of measurement was a freely suspended steel rod of circular cross section. The responses of the analyzed structure were measured by accelerometer and laser vibrometer. The results of these measurements are also discussed in the paper.

scholarly journals Modal control based on direct modal parameters estimation

2017 ◽  
Vol 24 (12) ◽  
pp. 2389-2399 ◽  
Author(s):  
Baptiste Chomette ◽  
Adrien Mamou-Mani
Keyword(s):  
Frequency Domain ◽  
Controller Design ◽  
State Space Model ◽  
Parameters Estimation ◽  
Modal Parameters ◽  
Rational Fraction ◽  
Modal Control ◽  
Identification Algorithm ◽  
Human Intervention ◽  
Rational Fraction Polynomial

Modal active control is based on a state model that requires the identification of modal parameters. This identification can typically be done through a rational fraction polynomial algorithm applied in the frequency domain. This method generates numerical problems when estimating high-order models, particularly when moving from the basis of orthogonal polynomials for the modal basis. This algorithm must therefore be applied independently on multiple frequency ranges with a low order for each range. In this case, the controller design cannot be automated and requires a lot of human intervention, especially to build the state space model. To address this issue, this paper presents the application of the direct modal parameters estimation (DMPE) algorithm for active modal control design. The identification algorithm is presented in a simplified version with only positive frequencies. Unlike other classical identification methods in the frequency domain, the DMPE algorithm provides a solution with a great numerical stability and allows estimating models with a higher order. Using this method, the design of the controller can be largely automated and requires a minimum of human intervention. After a theoretical presentation, the proposed method is experimentally validated by controlling the vibration modes of a suspended plate.

Comparison of Extraction Methods for the Determination of Vitamin B1 and B3 in Foods

2020 ◽  
Vol 49 (8) ◽  
pp. 822-828
Author(s):  
Jimin Yoon ◽  
Naeun Kim ◽  
Ahyeong Jeon ◽  
Jihyun Kwon ◽  
Sang-Hoon Lee ◽  
...  
Keyword(s):  
Vitamin B1 ◽  
Extraction Methods

Identification and Determination of the Components of Garden Sage (Salvia officinalis L.) Essential Oil, Isolated by Different Extraction Methods

2020 ◽  
Vol 75 (11) ◽  
pp. 1451-1460
Author(s):  
Z. A. Temerdashev ◽  
V. V. Milevskaya ◽  
L. P. Ryabokon’ ◽  
N. N. Latin ◽  
N. V. Kiseleva ◽  
...  
Keyword(s):  
Essential Oil ◽  
Extraction Methods ◽  
Salvia Officinalis ◽  
Salvia Officinalis L

Determination of collapse moment of different angled pipe bends with initial geometric imperfection subjected to in-plane bending moments

2021 ◽  
pp. 095440622199640
Author(s):  
Manish Kumar ◽  
Pronab Roy ◽  
Kallol Khan
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Circular Cross Section ◽  
Initial Imperfection ◽  
Bend Angle ◽  
Bending Moments ◽  
Element Analysis ◽  
Geometric Imperfection ◽  
Initial Geometric Imperfection

From the recent literature, it is revealed that pipe bend geometry deviates from the circular cross-section due to pipe bending process for any bend angle, and this deviation in the cross-section is defined as the initial geometric imperfection. This paper focuses on the determination of collapse moment of different angled pipe bends incorporated with initial geometric imperfection subjected to in-plane closing and opening bending moments. The three-dimensional finite element analysis is accounted for geometric as well as material nonlinearities. Python scripting is implemented for modeling the pipe bends with initial geometry imperfection. The twice-elastic-slope method is adopted to determine the collapse moments. From the results, it is observed that initial imperfection has significant impact on the collapse moment of pipe bends. It can be concluded that the effect of initial imperfection decreases with the decrease in bend angle from 150∘ to 45∘. Based on the finite element results, a simple collapse moment equation is proposed to predict the collapse moment for more accurate cross-section of the different angled pipe bends.

New advances in the method validation, extraction methods and measurement uncertainty for the determination of water-soluble hexavalent chromium in hydraulic cement

Talanta ◽  
2021 ◽  
Vol 232 ◽  
pp. 122286
Author(s):  
María Melania Ramírez-Quesada ◽  
Jimmy Venegas-Padilla ◽  
José Pablo Sibaja-Brenes ◽  
Bryan Calderón-Jiménez
Keyword(s):  
Measurement Uncertainty ◽  
Hexavalent Chromium ◽  
Method Validation ◽  
Extraction Methods ◽  
Water Soluble ◽  
Hydraulic Cement
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